Note to readers coming from the Cub Crafters site: This information is not directly applicable to Lycomings. The 6% power increase came from a major change in the intake configuration, not from the EFI. Look at 360 Lycomings; Yes most of the ones with a carb are 180HP and most of the injection are 200HP, a 10% gain, but this is ignoring the fact that the 200HP models (the -As and -Cs) have a very different angle valve head and a tuned induction system. Note that the 360s that just change from a carb to injection, (the -B series) remain at 180hp. There is no magic power in FI. Also note that all Corvairs in the last decade all have electronic ignition. If a Lycoming has a perfect set of mags and they are replaced with electronic ignition, there is no reason to expect a measurable peak power increase. The far easier way to get a small power increasein almost any motor without adding any complexity is to turn it slightly faster. -ww.
Here are some notes and photos of five fuel injection systems for the Corvair. The first three are electronic systems, the latter two are mechanical injection. Fuel injection is a topic that many builders ask about. I think a lot of the interest is generated by the awareness that high performance certified aircraft have mechanical fuel injection. A number of builders have learned that these systems are comparatively immune to carb ice. Beyond this, very few people have a good concept of the pros and cons of these systems vs. carbs. Even guys who know a fair amount about engines often miss important realities about the applications of these systems. This post gives a general overview, and covers details that are rarely discussed when builders bring up the topic of injection.
Electronic injection is the type of system that modern cars use. There have been a number of auto engine conversions that came from cars that had EFI that have gone on to fly in planes, and some suppliers to certified engines are just starting to look at EFIs fitted to Lycomings. What gives modern cars good mileage, long plug life, low emissions, etc., is the ability of the EFI system to operate in closed loop mode. It does this almost all the time the car is cruising down the road. When it is not doing this, it is operating in “open loop mode” and falling back on the computer’s pre-programmed data that says ‘at 3150 rpm and 26.5″ MAP squirt in so much fuel.’ In open loop, much of the advantage of EFI disappears. Up to here, what I have typed falls into the category of “Lots of people know this.” Here is the corollary only a few people understand.
In aircraft applications, the EFI systems almost never operate in closed loop. If you are going to cruise your aircraft at 75% power, it will spend its whole time in open loop. This is true with liquid cooled engines, but really true with air cooled ones. Very few engines run with air fuel ratios of 14.7 to 1 at high power settings. They mostly run 12 to 1, or richer, and O2 sensors have a hard time getting the loop to close at rich ratios. Sure, there are exceptions to this, like wide band sensors, but you really cannot compare a made at home system to a 2007 Corvette with perfectly tuned knock sensors, 1 million lines of code in memory, and the ability to look at individual cylinder exhaust pulses as they pass the O2 sensor. Even still, GM knew that 75% sustained power in the Vette would be about 155mph, and the car would spend .002 percent of its life there, so it’s OK if it is in open loop at that point.
After CC #9, I got Mark from Falcon to walk over to Jann Eggenfelner’s hangar. Jann is the king of Subarus, and like it or not, most people concede that he has flown more different types of EFI than anyone else. I know him fairly well, and he is very smart, and unbelievably tenacious. With Mark’s OEM background and Jann’s flight experience, they had a very detailed high speed data exchange. The recurring point that Jann kept coming back to is that no system, including the Subaru OEM stuff, will reliably operate in closed loop at aircraft power settings. In open loop, EFI begins to look like a very complex, high pressure, electrically dependent carburetor.
Above, the EFI 2,700cc Corvair built by Mark at FalconMachine.net in 2007, at power on my dyno. The urethane wheel directly reads foot pounds of torque off the digital scale. Note that this engine is using headers with collectors. We also tested it with cast iron manifolds and mufflers. It has distributorless ignition. Six LS1 coils are mounted on the sides of the black airbox. After a lot of careful calibration runs, this engine achieved a 6 percent power increase over a carbureted Corvair. Merely saying this will certainly activate the keyboards of armchair EFI experts, but it’s simple measured facts. Before questioning the test methodology or results, consider that Mark has earned his living with these systems for the past 20 years and the instrumentation included such niceties as a $500 laboratory grade digital oxygen sensor. Anyone who says that adding EFI to an engine like a Corvair will add 30% more power is just making their information up. The system above was tested a number of hours but was not flown. The controller on this was a Tracy Crook unit. This engine was equipped with equal length intake runners. It was laid out to fit in a 601/650 cowl.
This is a redundant ignition, electronically fuel injected, fifth bearing, 2,700cc test engine built by Roy at RoysGarage.com in 2007. It features coil on plug technology and throttle body injectors along with a rear mounted 40A alternator. It is mounted on Roy’s 701. It was run and tested, but not flown. Roy also has extensive experience with digital EFI systems. This provided good data, but in the end, Roy thought about the complexity he was applying to a very simple aircraft and chose to finish the aircraft with a simple gravity feed carb instead.
My thesis on EFI in 5 simple points:
1) Any system that uses lower pressure fuel is less likely to leak. Gravity is better than 5 psi, and 5 psi is better than 40. EFI runs at high pressure.
2) Any system that uses no electricity is better than one that uses a little, and one that uses a little is better than one that uses a lot, especially if the one that uses a lot needs it to be a certain voltage, like digital EFI.
3) Any system that has less parts and connections is less likely to fail. Digital electronic connections, working at low voltages, are very sensitive to corrosion, temperature and vibration, things planes produce more than newer cars.
4) Almost all the things that EFI advocates hope for, HP increase, smoothness, fuel efficiency, and reliability, will prove elusive or minimal. Before debating this, seek out a single flying system that will go into a closed loop in cruise flight. Realize that monitoring voltage and fuel pressure is not a work load reduction from using carb heat.
5) The only good reason to work on an EFI Corvair is because you want a challenge, and this is more important than finishing your plane soon. This is a valid position, and I support anyone who knowingly makes it.
Let me introduce a man who personifies point number 5, Rex Johnston. As far as I know, Rex is the first guy to ever fly an EFI system on a Corvair powered aircraft. This makes him someone special, because there were a lot of hurdles to jump over. His Corvair powered plane is a Davis DA-2, a sporty little two-seat sheet metal aircraft. Rex’s work is an outstanding example of building to meet a challenge that you personally feel. He was not after some illusive performance goal, he was just looking to challenge himself and learn a lot. Hats off to Rex.
Above, the underside of Rex’s plane. His system is a Holley Projection throttle body unit, that Holley originally sold for 258cid Jeeps. Rex’s engine is a 3,100cc Corvair. Notice that it still has carb heat. A project like this isn’t for everyone. It takes significant experience building to be able to develop and flight test a complex set of systems like this.
The standard for aircraft injection are mechanical systems. These use no computers, they work entirely on a balance of pressures and flows. They meter fuel very accurately, and offer instant throttle response. They typically operate at 25 psi, somewhat lower than EFI. Unlike EFI, they are not sensitive to fuel pressure changes, and they do not need an external pressure regulator. By design, they are always operating in open loop mode. Because these systems have been used on aircraft for half of the history of powered flight, they are fully understood and developed.
The above photo shows an Airflow Performance mechanical fuel injector specifically calibrated for the Corvair. For size reference, a core Stromberg carb is at top left in the photo. Below it is the gold flow divider. One of the installation advantages of mechanical injection is the extremely small calibrated nozzles. Packaging six electronic injectors that will fit in a tight cowl is challenging. Mechanical injectors have an 1/8″ pipe thread on the bottom and are roughly 1/4 the size of electronic injectors. Airflow performance is owned by Don Rivera, a very smart guy who has owned and driven land-based Corvairs. This system is made in the U.S. The parts for this system cost over $3000. Corvair builder Sarah Ashmore is putting one of these on her Personal Cruiser airframe. Her heads were modified for the injectors by Mark at Falcon. She works in the aerospace industry and made the choice to equip her aircraft with a system that met her specific goals.
Above is a photo of a Precision mechanical fuel injector. The pictured unit is a port injector, but they also make a very compact unit that has the same quality, but has just one injector built into the body of the unit. The system does not require any modifications to the Corvair’s heads or intake, as the unit bolts onto the same flange as an aircraft carb. Peter Nielson of precisionairmotive.com is our engineering rep who has supplied us with a test unit, which we are now testing on a 3,000cc Corvair. This system is about $2,500. Precision knows quality, as they produce parts for and service certified fuel systems. We will release more data as we move through the tests. We are planning on flight testing this on Woody Harris’ 601, and Dan Weseman is planning on using the aerobatic capability of the system on the prototype of his new Corvair powered design, the Panther.
Today, 99.75% of Corvair powered planes use carbs. However, I think the Corvair is a good platform for fuel injection, and there are a small number of airframe applications that could really benefit from a fuel injection system. While there has always been a lot of talk about EFI, only a rare few clever and persistent builders like Rex Johnston will see the project through. I personally feel that the mechanical systems offer the best reliability and most proven track record, having flown in many demanding settings on other engines. As always, the proof and the progress is in the hands of the builders, the people In The Arena.
The subject here is the most popular light aircraft carb of all time,the Stromberg NAS-3 and 3A. These were fitted to roughly 70,000 aircraft over a production run that lasted several decades. It looks like a very simple carb, and in some ways it is. But in reality, it is a highly engineered design that was produced by the world’s leading manufacturer of aircraft fuel systems. At the time of production, this was Stromberg’s most basic product. They also made ultra sophisticated pressure carbs that were on the most powerful multi-row radials. This carb comes with an experience pedigree that no experimental carb can come close to matching.
Above, a Stromberg NAS-3 mounted on Dave the Bear’s Wagabond. We finished this aircraft in our Edgewater hangar in 2004, when Dave worked as part of “The Hangar Gang.” We used this combination with a 2,700cc Corvair and a Sensenich 64×35 prop to conduct a lot of jetting tests. We were not new to the Stromberg, as our Pietenpol, and our second test mule, Gary’s Skycoupe, both used the same carb. Besides these Corvair powered planes, the carb was also on several certified planes we had at the same time like Grace’s Taylorcraft and Gus’ 120.
When it comes to gravity feed carbs, I like Strombergs because they have literally millions of hours feeding air and fuel into flight engines. I know them and trust them, and if I had any little issue with it, I’d have a mountain of expertise to draw on, not just other people flying one, but professionals with decades of documentation. I don’t have to think about it, it isn’t a variable. The one limitation on the carb is that it is not suited to use on a plane that requires a fuel pump. Thus, it isn’t good for a 601XL or a 650, but it is a good match for any high wing plane or one with a header tank. (The sole exception to this is the 750 because the factory now recommends that builders use a back-up fuel pump because of the plane’s high angle of attack capability.) I consider the Stromberg a much better carb for the Corvair than any of the other gravity feed carbs like a Monett Aerocarb, Posa, etc. The typical price for an old but functioning NAS-3 is $250. If you shop around, you can find them for half of this.
Above, an overhaulled NAS-3 that went on the Pietenpol of Dave Minsink.
The carb comes in two venturi sizes, but they are interchangeable, so if you have a core from a 65hp with a small 1.25″ venturi, you can replace the venturi with a larger 1.375″ one that came on the 85 and 90hp carbs, and you can rejet the carb to the bigger model. If you wish to have your core rebuilt, the best place we know of is D&G Fuel Systems in Niles, Mich. It is owned by a good guy named Russ Romey. I have worked with Russ over many years, and dozens of Corvair powered planes are flying with carbs that he rebuilt. If you don’t have a core, you can buy a Stromberg outright from Russ.
When Dave the Bear’s Wagabond was finished, Gus did the original test flights. One of the things we carefully worked out was the jetting. Here is something not to try at home: We did successive tests to slightly pull the mixture on full power climbouts, looking for a slight increase in rpm, which would indicate the carb running slightly rich to protect the engine from detonation. This was done carefully, and still Gus aborted a take off after reaching 150′ because the engine was hinting at detonation at the combination of timing and mixture we were trying. Dave kept rejetting the carb until we got what we needed. From the EGT reading, I think that the correct A/F ratio at this setting was about 11:1.
We spoke with Russ from D&G during this testing and when we were done, he began to jet the Strombergs he sells for Corvairs this same way. This is what we came to call a “Super Stromberg” to differentiate it from others jetted differently. The Corvair will run with one taken directly off a 65 or 85 Continental, but if you run it hard to get the engine’s full potential, it will be too lean. If you’re close to flying, and you know that you’re eventually going to have the carb redone internally, let me encourage you to do it before you start flying. Dave’s plane ran a whole lot better when we had it finished, and today people can just get their Stromberg to run this way right off the bat. The jetting works on any Corvair from 2,700-3,000cc.
Some models of the carb have a mixture control, others do not. The ones we used in our Pietenpol and the Skycoupe had no mixture. If I were planning on flying over 10,000′, I would have one, otherwise I would use either model. Most of the light planes that originally came with NAS-3s only had a mixture control as an option, not standard equipment. Although this may sound a little crude for an aircraft carb, the mixture control isn’t a requirement for flying. People logged a lot of happy hours flying J-3 Cubs without a mixture control.
One of the most common questions asked about Strombergs is their susceptibility to carb ice. Although it is technically more prone to carb ice, I treat every carb as if it were prone to carb ice and I use carb heat on every plane and utilize it habitually any time the power is reduced below cruise setting. I consider the ice issue a small point compared to the other issues experienced by unregulated flat slide carbs. Sticking slides on planes that are on short final is far more of a risk . The Stromberg’s butterfly throttle plate always opens smoothly, and the carb is well known for holding an adjustment throughout a very wide range of temperatures and conditions. I have flown the NAS-3A on Grace’s Taylorcraft in temperatures ranging from 15F to 105F, and it does this without adjustment. Other than having the filter screen cleaned, the logs show that the carb on her plane has not been worked on since 1974. This is reliability.
Another point to consider is that the carb is very tolerant in changes to fuel density. A great number of certified planes that use these carbs have auto fuel STCs. This change is just a paperwork change that goes with the plane; there is no adjustment to the carb to start running auto fuel. Likewise, the jetting will not change when you alternate between auto fuel and 100LL in an experimental aircraft fed by a Stromberg. This is not so with some experimental aircraft carbs. These two fuels have different densities, and some carb designs really need to be rejetted when changing back and forth between fuels. As much as I like working on planes, this is a lot of extra work compared to having a carb like a Stromberg.
The Marvel MA3-SPA is the only carb commonly used on a Corvair that has an accelerator pump. All the others, including the Stromberg, need a primer for starting. When the Stromberg has one, it will start in almost any weather you would choose to fly in. Grace’s Taylorcraft engine is a C-85, but it is equipped with the exact same Stromberg carb we are speaking about. With no preheat, and the engine cold soaked at 20F, I can give it 3 shots with the manual primer (same type as in the Aircraft Spruce catalog #05-19920) , open the throttle slightly and crank the starter for no more than 2 seconds. The engine will light right off and run at a high idle. ( I let it warm up for 5 minutes with the carb heat on. Not only does this vaporize gas better, it does also slightly enrichen the mixture by lowering the density of the air entering the carb.) It was not required to work the primer once the engine started, I just leave it locked. I turn the carb heat off for a few seconds every minute to evaluate how well it was working. Within one minute, turning it off gives a 75 rpm rise, indicating it is flowing hot air. Even though they are different engines, this data should give people thinking of using the Stromberg a good indication that they will start easily when cold. On an actual Corvair, the higher compression and the stronger spark would make the engine light off even faster.
The Stromberg is an affordable, proven carb for gravity feed Corvair powered planes. I consider it an excellent carb for a Pietenpol, Kitfox, Highlander, Wagabond, and many other airframes. If you have a question about a specific airframe, drop me a note, I will be glad to share what I have learned.
This blog is a great start to 2012. Thanks. I have a suggestion for a discussion…post a brief summary of the differences in displacement choices for those of us still early in the engine build or still deciding? And a question…planning a West Coast Corvair College this year?
Good to hear from you. First, we are thinking of holding an event in California this year. We are looking at May 5th weekend in Chino at Steve Glover’s hangar where he runs NVaero. Steve is having a KR gathering there and an open house at his shop that weekend. I have known Steve for many years, and his two commercial hangars at Chino are well equipped to have a very productive College. Steve and I think that having the two events on the same weekend would be a good exchange of people and ideas. The Corvair is a very popular engine choice in the KR, and Steve wanted all Corvair builders to understand that they are more than welcome at his place. (Besides owning a series of KRs, Steve also has a Long EZ and a TriPacer; he is an all around aviation guy.) The only thing that has kept me from putting it on the schedule is a 50/50 chance that the weekend will conflict with my brother-in-law’s retirement from 30 years in the Army. In our family, such an event is “AHOD” (all hands on deck). We will know more in two weeks, and post the information here, under the “Events” heading.
On the subject of engine displacements: Today I encourage people to build one of three engine displacements that makes sense to them. Here is a breakdown:
2,700cc, 100hp, based on stock Corvair cylinders which are rebored from .020″ to .060″. Requires no machining to case or heads. Uses either Sealed Power or Clark’s Forged pistons. This is the engine that 85% of builders are working on. More than enough power for a Pietenpol or a KR, a good choice for a 601 or 650. There are many flying examples of each of these airframes with this engine displacement that have individually logged hundreds of hours each.
2,850cc, 110hp, based on Clark’s heavy duty brand new full fin cylinders bored .105″. Requires no machining to the case or heads, it is a straight bolt-together engine. This engine uses U.S. made forged pistons that are available through us. We sell a Piston/Ring/Cylinder/Rod Kit for $1,750. The pistons have a 7.7cc dish in the head to lower the static compression while maintaining a very tight quench area, giving the combination of good combustion and outstanding detonation resistance, even on unleaded fuel. The engine is also the best choice for later turbo-charging. The displacement is a good choice for any Corvair powered airframe. Photos of CC #19show Jeff Cochran’s running 2,850 built for his 750, and you can look at CC #21’s coverage for pictures of Clarence Dunkerley’s running 2,850 that he built for his Cleanex. Our Web site coverage of Oshkosh 2011has a lot of photos of Woody Harris’ 601 that he flew on a circumnavigation of the U.S. Woody’s plane is powered by a 2,850.
3,000cc (3 liter) engine, 120hp. This is based on custom machined cylinder castings that are related to VW castings. The bore size is 92mm, but we use the HD casting that is the same as a 94mm VW cylinder. The piston in this engine is the big brother of the 2,850. It is forged in the same U.S. factory, and features a 10cc dish. This provides the same combustion characteristics in a slightly larger displacement. This engine does require having the cases bored slightly for the larger cylinder spigots and having the head gasket area opened up slightly. This job must be done accurately, and the price is included in the Piston/Ring/Cylinder/Rod Kit. This displacement is a good choice for any Corvair powered aircraft. It has flown on both the 601 and 750.
Given these three engines, we no longer steer builders toward previous engines like the 3,100. There is nothing wrong with 3,100s, but they did prove difficult to build for many people without a lot of previous experience. The internal dimensions were a compromise because the 3,100 used a modified VW piston with a different compression height, requiring the engine to be built with custom length pushrods, etc. The 3,000cc engine was our clean sheet of paper, based on what we knew after 10 years of building 3,100s. A 3,000cc engine is a better engine from a number of angles, and is a better engine choice for builders considering using unleaded fuel in the future.
Every flying Corvair needs four pieces of cooling sheet metal that came from the factory. These pieces are the two under-cylinder baffles, and the two end plates on the firewall end of the engine that go between cylinder #1 and the distributor and on the other side between cylinder #2 and the oil cooler. These four pieces of sheet metal are just as vital to the engine’s cooling as a radiator hose is to a liquid cooled engine.
Because a lot of engines have very filthy or rusty metal, we have decided to make sets available to builders. They are very time consuming to clean, even if you have a blasting cabinet. I took a large collection of these pieces to our powder coating guy, and let him professionally blast them, and then powder coat them matte black.
They are not required to be powdercoated on your flight engine, but getting a set from us does save some time, and they look very nice, a good compliment to a sharp looking engine. We are selling these sets for $99 plus your old parts by check or money order payable to William Wynne, 5000-18 US HWY 17 #247, Orange Park, FL 32003. If your core came without, please send us $120.
Please email us at WilliamTCA@aol.com to let us know they’re on the way. We’ll reserve a set for you.
As an introductory offer, we are going to cover the shipping of our parts to anywhere in the U.S. We will do this through the first 10 sets in the shop.
Above, the two end baffles in the bag, the two under-cylinder baffles are below them. All of the parts are powdercoated matte black.
Above, 14 sets of under-cylinder baffles ready to be sent as part of the four piece cooling sheet metal sets. In the background, freshly done powdercoated Valve Cover Sets.
Valve Cover Sets are available for shipping in the U.S. for $159 by sending a check payable to William Wynne with your old valve covers to 5000-18 US HWY 17 #247, Orange Park, FL 32003. Please email WilliamTCA@aol.com with your choice of Red, Blue or Black as well as your horsepower or FlyCorvair.com designation.
Our friend and welder, Vern Stevenson, has had a lifelong love affair with all things mechanical. He has built a number of different aircraft, mostly light single-seaters. His hangar is just down the way from ours, and a tour of it is an education of how much a man with imagination, skill and some material can do. In addition to his aircraft, the hangar houses a motor home made from a former Greyhound bus, a 1968 Shelby GT-500, Various Big Block trucks, a 300 HP Corvair sand rail, a Porsche 914 powered by a 327 Chevy, and many others, all handmade by Vern.
Vern’s current passion is aerodynamic cars. Growing up in humble circumstances, Vern fully espouses the pure hot rodding of the 1950s, an era that placed creativity and mechanical ingenuity above all else. I have been to rat rod car shows with him, and he points out that his friends have always been doing it “old school.” None of them are interested in a car or a plane that is just another purchased product. It has to be handmade to have any interest to them. Although they could buy any car part they like, or most finished cars, they don’t. To Vern and his friends, one of the rewards is demonstrating incredible skill at bargain hunting, horse trading and bartering. Among his friends, Vern is the unrivaled champion of these talents, and the two projects have a parts total price that reflect this.
Above is Vern’s “Streamliner.” It was inspired by Craig Breedlove’s land speed record attempt car, “The Spirit of America.” Vern’s car is aimed at looking the part, but taking a shot at 70 MPG. The car has 3 wheels, and is considered a motorcycle in Florida. The aluminum bodywork is all salvage material. It hides a mild steel frame that looks like an aircraft fuselage. The canopy came from the Sun ‘n Fun flymart for $30. The engine is derived from a very early Dodge Omni, and I think it is a VW based design, something like a Rabbit engine. Vern has handmade a very tall set of rear wheels to cut the rpm at speed. The weight is around 900 pounds. The car is a two-seater. Vern keeps good track of his spending as a matter of pride. He has several hundred hours of work in the car, but he has less than $500 in total materials.
Above is Vern’s yet unnamed project. He has been messing with it part time for the past two months or so. It is also a three-wheeler, and makes the grade in Florida as a motorcycle. (Car insurance is not cheap in this state, and motorcycles are exempt from the requirement.) If you look closely, you can see that the back half of this creature is a two-seat Lancair fuselage. The front is a Geo Metro front end. As crazy as it sounds, Vern has artistically blended the two. It isn’t going to win the New York Auto Show, but every motorhead that has seen it has been captivated. The design was driven by the fact that Vern’s girlfriend didn’t like the tandem seating of the Streamliner. The digital camo paint job is an experiment in how you break up the shape differences of the front and back halves.The rear end is out of a Suzuki motorcycle. There is a steel tube subframe that joins the A-pillars of the Geo to the longerons and the spar carry through of the Lancair.
Above, a look inside the new project. It retains most of the dash and the pedals of the Geo. The steering column has been moved over about 3 inches. The wheel has a race car style quick removal to making getting in easier. The hinge mechanism for the canopy is the rear gate hinge from a minivan. The seats are 914 leftovers. Vern is hoping for a comfortable cruise and 60 mpg. By trading some time and parts, Vern has kept the budget ultra low. He is just now getting to $150 of cash laid out. He claims that he is willing to “go all the way” (Spend $500) to see the project through being roadworthy. If either of these vehicles have special driving requirements, it isn’t an issue, Vern has a 40 year history of driving anything with an engine from Stock Cars to excavators. He is a gifted motorcyclist, and he is sensitive enough to machinery that he taught himself to fly ultralights without ever taking a single lesson. In the 1980s ultralights were powered by a number of two strokes not noted for reliability. In his first 500 hours he had 18 engine outs but never got more than a scratch.
Neither of these two are directly related to flying Corvairs, but I stuck them in here to point something out. While Vern is speaking of, or working on these vehicles, he is among the happiest people in the World. The simple joy of creating something with your hands using tools is a real joy in life. If you are at home and it has been a while since you have had that kind of rewarding feeling, make a plan to get back to it. Many people get into homebuilt aircraft because they falsely believe it to be an inexpensive way to having a completed aircraft. Building to these people is a necesscary evil. These people actually have a very poor record of completing planes because they derive very little joy from the process. If you have any doubt that a great number of people in homebuilding are driven by just wanting the plane and have no desire to learn or build their craftsmanship, look at how much advertising space is devoted to dubious claims of 300 hour build times and questionable stories about how few skills it takes to build some designs.
Although knowing what you’re up against timewise is a valid question, and you should know if a design requires you to be a machinist, specifically trying not to enjoy the building process nor learn anything has sold a lot of kits, but it hasn’t finished many of them. The build it yourself nature of the Corvair, and the fact that learning here is a goal, not an evil, makes the Corvair movement different. We are glad to assist anyone who is entering The Arena to Learn, Build, and Fly in the company of other friends who feel the same way.
When we assemble an engine, one of the steps that I take is to test the head studs before we put the case together. It is a quality control step, and if one of the studs is slightly weak, I want to know it before assembly because it is a lot easier to fix before you build the engine. The procedure is fairly simple, and the tooling isn’t very elaborate. I bring my set to Collegesand show builders there the process in person. Here, in a few paragraphs and pictures, you can get a good overview.
Based on building several hundred engines in the past 20 or so years, the chances of getting a weak stud are low. About every 10th engine will have one. These studs were overstressed on disassembly or were overdone on a previous build. They look good on the outside, but the stud has been taken past its yield point.
Above, the test set up.The test is made easier with a high quality torque wrench, but it will work just the same with a beam type wrench. The small spacer on the arm allows the same tool to measure the longer top studs. The little tube is just a collar for the spacer, not required. The ends of the tubes need to be fairly true to the tube, the best method is turning them in a lathe, but careful work on a belt sander will do the same task.
Backing up a moment, I am going to assume that you have pulled and replaced all the studs that had hard tool marks from previous owners’ vice grips, and also pulled all the studs that have harsh rust pits. Mild surface corrosion is not an issue, and a missing thread at the top of the stud on the fine thread end isn’t a reason for rejection either.
Many years ago, I taught engineering labs at Embry Riddle in the Materials Department. People who have been through these classes know what a Tinius Olsen pull test machine is. For the rest of the gang, it is an immensely strong set of jaws pulled apart by a very powerful hydraulic system. Many of these systems can pull 50 thousand pounds without bogging down. A test sample of material is put between the jaws and very slowly pulled apart, while computers measure the length and power of the pull. This all happens at a very slow rate, pulling 1/2″ can be slowed down to take several minutes.
Instead of demonstrating the machine on expensive test samples, I brought in bundles of Corvair head studs. We pulled them apart in every class. It gave both myself and the students a much better understanding of the effects of corrosion and mechanical damage like tool marks. A used Corvair stud in fair condition may not look that strong, but it takes over 10,000 pounds of pull to get one to neck down and break. Because of this testing I have a pretty good idea of what is too much damage on the outside of a stud. But the testing in these photos tells the condition of the stud on the inside of it.
The test tube is a piece of .188″ wall 4130 tube, 3/4″ in diameter. I welded a washer on the bottom it give it a bigger footprint. I polished the bottom of this so that it doesn’t leave any marks where the base gasket goes. On the top of the tube there is a very high quality hardened washer and an ARP 3/8-24 nut. (This can be done with lesser hardware, but remember, the goal is to test the stud, to the strength of the test hardware.)
Above, the washer and nut are in my hand, the tube is viewed end on showing the wall thickness. The tube has a little stand welded on it from a 2004 test series where we measured how much the studs stretched when they are torqued. At full torque, the studs are almost .035″ longer. This is an outstanding design feature. The engine is “spring loaded,” and the studs maintain their clamping force through a very wide range of engine temperatures, and expansion and contraction cycles. Engines like the Jabaru have very short bolts that hold the heads on. Bolts like that typically need continuous checking, because even a slight amount of material compression under the head of the bolt will result in a loss of torque on a short fastener. Conversely, a long stud is comparatively immune to this. Certified aircraft engines have the heads permanently screwed to their cylinders for a number of other design reasons, but engines like the Corvair, VW and Porsche all use the long studs. These are part of a well calibrated system, and are the primary reason why you should not use an aluminum cylinder on a Corvair. Porsche 911s eventually had aluminum cylinders, but they also had uber expensive “Delavar” studs, with an expansion and contraction rate that was compatible with their alloy cylinders. Companies that have offered aluminum cylinders for Corvairs have not taken expansion into consideration. Making the studs thicker or stronger actually only exacerbates the issue. Corvairs are designed for steel or iron cylinders, and they have an outstanding record of reliability with them.
Coat the threads on the stud and the washer with ARP Ulta torque lubricant. Drop the tube over the stud, run the washer down and then the nut. Carefully torque the nut to 15 foot pounds. Noting the clock position of the wrench handle when you start, raise the torque to 20 pounds. Typically this will require turning the wrench about 45 degrees on the short studs, about 55 degrees on the long ones. Next, raise the torque to 25 pounds slowly. Now, the critical observation: It should take the same 45 or 55 degrees of rotation on the nut to get the new torque increment. There is an acceptable range, and you shouldn’t be too concerned about a variation of 15 degrees or so. But, if you have a stud that requires 100 degrees of rotation to go from 20 to 25 pounds when all of the others took only 45 degrees, you have found a weak stud, and it needs to be replaced.
Above, the tool on a lower stud, giving a better view of the auxiliary arm on the tube from a previous test. The arm plays no role in this stud check up. Note the plywood under the case. Don’t let the mating surfaces sit on a steel table, concrete or any other rough or hard surface.
A weak stud undetected is not going to lead to an engine failure. Typically, when a builder has a bad stud, he is torquing up his heads and notices that one stud turns way too far. This is the point where it would have been better to test before assembly. But even if it goes undetected at this point, the typical stud will not break, it just will not be clamping as tight as the others holding down the cylinder. In time this can lead to a blown head gasket.
Above, the task in action. The torque wrench is a $300 Snap On item, pricey, but an outstanding piece of quality. Ours is called Excalibur. If you ever meet an A&P mechanic and he has a pair of sunglasses or shoes that cost more than his torque wrench, be guarded about taking his advice. Paul Gauguin’s paintbox was more valuable than anything else he owned. The brush doesn’t make the artist, and the tool doesn’t make the mechanic, but it is a measure of whether a man considers his work a craft or just a job.
A Corvair is a very tough engine, and I have seen several of them fly a long way on a blown head gasket. The engine makes power on the cylinder even if the gasket is blown because at RPM the compression doesn’t have time to bleed through a tiny gap. A blown head gasket on a liquid cooled engine is a different story because it can mean a loss of coolant either out of the engine, into the crankcase, or into the combustion chamber. Liquid cooling is better in theory, but air cooling is better in practice. (A liquid cooled engine is less likely to ever blow a gasket, but if the discussion is about aircraft, you are mostly concerned about how the powerplant behaves after the event, not just the likelihood of the event.) In Corvairs, I have seen about 10 engines with blown head gaskets in the past 15 years. Almost all of these were caused by the timing not being set with a light at the static rpm. Only one or two were caused by a weak stud. Both of these causes are easy to avoid. Testing your studs before assembly avoids a small chance of a hassle on final assembly.
On final assembly, be alert for studs that take a lot more rotation to reach the rated torque value. When studs are torqued with ARP ultra-torque, we have done very careful tests to prove that you are getting the same clamping value at 26 foot pounds as a builder with light oil is getting if he torques the stud to 35 pounds. Use ARP, and stop when you get to 25-26 pounds. If you go all the way to 35 you are exerting a lot more force than required, and will actually be doing damage. Remember, you got into experimental aviation for the learning and adventure. Take pride that successful Corvair engine builders know a lot more about how engines are really built than any other group in experimental aviation.
Submitted for your approval, three stories I wrote in 2009, 2010, and 2011. For me, the human element of aviation has always been the focal point of my lasting love for it. I love the machinery, the creativity and the history, but the story of the individual, the person, is what intrigues me.
The stories here cover experiences of Astronauts, an Airline captain, and a Navy attack pilot. As a humble general aviation pilot, I will never fly into space, sit in the left seat of an airliner, nor fly in combat. Yet I hold that anyone who has built a single part, soloed a plane of any kind, or has spent years with the inner feeling that they were born to be part of the human panorama of aviation, can relate to the stories below.
The stories are not pleasant. An average day in the life of a professional aviator is one of reliable performance of duty. It is only under extreme circumstances that the nature of their character is revealed. I am a small part of one subset of aviation, and I will not face these same challenges, yet every experimental aircraft builder understands that he had to move beyond the fears that keep the rest of society sentenced to a mundane life, every soloed pilot understands the measure of courage required to go alone, and every pilot who takes a person aloft understands the responsiblity of the words “Pilot in Command.”
The 20th Century saw the discovery of both the North and South Poles, the Conquest of Everest, and the Development of Aviation from the Wright brothers through landing on the moon. These are fascinating stories of human courage and endurance. I have spent countless nights reading this history. Yet, the only one of these experiences that I can know some small part of is the story of flight. Every human challenge that was worth the title of adventure involved actual risk. We endow the title “hero” on the aviators at the pinnacle of our calling. But unlike the general public, we have some understanding of who our heroes are, and the costs they were willing to bear.
Why Bother? (2011)
I stood in my front yard two days ago to watch the last Launch of the Space Shuttle. It was very moving to think about the 30 years of the program, years that have spanned my adult life. “Land of the free and home of the brave” are the end of our National Anthem, but who personifies this? For my choice, I think of Astronauts. I have friends who work in the space program, and they all acknowledge that despite the risks, there is no shortage of very qualified people to go. I can remember the exact spot where I was in Florida the day The Challenger was lost. I have been to their monument on the hillside above the Tomb of the Unknowns in Arlington National Cemetery. Before their flight, they were briefed that their odds of perishing were between 1/300 and 1/20. They went anyway, not because they were gamblers, but because they know that some things were worth doing even if they brought a very high risk of death. From the Challenger monument, it is a short walk to JFK’s grave. In 1962 he answered the question of “Why bother?” on the subject of Space flight:
“But why, some say, the moon? Why choose this as our goal? And they may well ask why climb the highest mountain? Why, 35 years ago, fly the Atlantic? We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win.”
When JFK said these words, he only had about 400 days left to live. Almost all of the people reading this have far more time left here. Question is, what will you do with it? Will you succumb to a “Why Bother?” mentality that seeks out false paths because they appear to require less learning and thinking? If the goal of a seafaring captain was to preserve the ship, he would never leave port. If someone’s goal is to save money and learn as little as possible, I humbly suggest that experimental aviation will prove to be a very frustrating and potentially very dangerous path. If “Why Bother” is such a person’s personal credo, they are never going to get any of the rewards while simultaneously taking astounding unnecessary risks. “Why bother” is much better matched to watching TV than building and flying planes.
I am 48 now, and I am past the halfway point. The exact length of the trip and the destination are unknown, but the road of memories behind get inexorably longer. Is it time to slow down, and ask “Why Bother?” Of course not. Anyone reading this has been lucky enough to be born one of the .1% of the people on this planet who has any hope of building something with their own hands and flying it, a dream so bold that it was beyond the reach of any person who every lived on this planet a mere 110 years ago. I am smarter than I was last year; I have learned more, I have honed my skills in the workshop and in the air. Aviation offers a near limitless arena in which to expand your life, to willfully choose the difficult and rewarding over the easy and complacent. This increase of capability and control that is the reward for honest striving and effort is the only substitute I have found for the nostalgia for a fading youth. I will never run a 5:30 mile again, never do 50 consecutive chin ups again, nor a number of other physical milestones from age 24. But I am a much better craftsman, pilot and person than I was then. Experimental aviation is the setting where I will find out how much I can study, understand and master in my life, not how little. For anyone else who feels the same way, I look forward to reading anything you have to say, seeing anything you have built, and being there when you arrive in your plane to a welcome of people who understand what is worth aggressively pursuing in life.
Speaking of Courage* (January 2010)
I just finished reading Captain Chesley “Sully” Sullenberger’s book, “Highest Duty.” Most of what I read are biographies, and it is rare that I find one from an aviator that isn’t worth reading. Sully’s seemed particularly good. He tells his story back to being an airport kid in Texas flying a Champ. Many polished biographies elevate the subject above reality. Reading this book I felt that it did a good job of shedding some light on the life of an aviator who is likely far more than the pages convey.
If you were in the USAF or work in the airline industry, he emerges as a strong advocate of these callings. Sully does a first class job of explaining the mindset and challenges of the professionals who inhabit these parts of aviation. His sudden popularity says something about America, and he touches on this in the book. He has a Facebook site with 675,000 friends. A few weeks back I read in the New York Times that his book has been a modest success, selling 92,000 copies. The difference in the numbers tells me that people out there are looking for a hero, but they care far less to know how their heroes think or what forces shaped their lives.
Sully has a simple message inside his tale: Training pays off, even if it isn’t tested, living your life prepared is its own reward. Today, many people want to know the tricks and inside tips on any subject they encounter. They want the Cliff’s Notes on life instead of actually living. Sully, who recounts a lifetime perfecting his craft, offers a strong indictment of such a mentality.
He is quite clear that the terms ‘hero” or “miracle” do not apply to himself or to flight 1549. He explains why he feels that the successful outcome was the result of training, team work, judgment and a few factors going their way. He clearly states that he did not expect to die. However, Sully does believe in both heroes and miracles, and part of the book explains this by contrasting his situation with that of Captain Al Haynes and United Flight 232.
Above, Al Haynes
We forget a lot quickly these days. America has long forgotten the name and the flight number, but most people in aviation remember the Sioux City accident of 1989. It happened my first year at Embry-Riddle. The crash was examined in great detail. At the University, we had a good idea of how low the odds of survival were, and most people felt the term miracle could very well apply. The crew of UA-232 fought to find any way to regain control of the DC-10. Haynes and crew had little reason to believe they would live. Through astounding skill, composure and leadership, Haynes made the best landing possible. 185 people lived. Many did not.
Captain Haynes came to speak at Embry-Riddle not long after the accident. His face still had the scars of the crash. He had been hailed in the media, but I felt being at Riddle had to be different. Here, we had students who had some real understanding of what he had pulled off. In “Fate is The Hunter,” Ernest Gann’s preface states that airline flying is a kind of a war story, where “the designated adversary always remains inhuman, frequently marches in mystery, and rarely takes prisoners.” I went to see him up close, to look at a Captain who had just returned from battle.
I stood five feet away and watched Captain Haynes as he spoke to people. He was kind and direct, but somewhat detached, with a look as if his real thoughts were far away. I was young and impressionable, and clearly before me was a real hero. He had salvaged a victory for a certain disaster. To my eyes, he was now among the pantheon of aviation’s eternal stars. Perhaps the distant look in his eyes was appropriate for a man who was proven in a field where all prepare for their battle, but very few are tested.
Fourteen years later, Captain Haynes is the guest speaker at the evening program at the Theater In The Woods at Oshkosh. Here, at the center of the world of flight, his star has never been diminished. The outside world has forgotten and moved on, but here, inside, the faithful fill every seat. It has been a full day of exciting things, but the people are now settling down as they take their seats. They will soon listen to a serious subject from a man known for a heroic deed. The last time I saw him I was part of a very young group, just at the start of our time in aviation. I looked around and saw where my classmates would be in another 20 years. The people around me had most of their flying logged away. Their gray hair and modest dress told outsiders nothing of the adventures these people had seen. They had led the strenuous life of challenge, and known its rewards…and perhaps its costs also. I looked around and guessed that many of them had lost a close friend to an accident. As soon as I formed that thought, I realized to 14 years later, I too, was in this last group.
The presentation was a technical one. Captain Haynes had made it his duty to frequently speak on behalf of preparation, teamwork, training, and when your test comes, not losing yourself or giving in to fear. He had spent the previous years communicating this, never accepting a fee or any kind of reward. They played the ATC tapes and slowly brought us to the moment of the crash. The audience was moved. Many people near me sat quietly wiping away tears in the dark. Perhaps they were thinking of friends, now long gone, wishing their friends had been luckier and had a man like Al Haynes for an instructor, a mentor or a co-pilot.
At the end of the presentation, a man, looking like he could have come from any EAA chapter in America, stood up. He struggled to gather himself and start a sentence. After a moment, in a choked voice, he got out “I just want to say I think you’re a hero.” A round of applause broke out, but it was quickly put down with a wave of Captain Haynes’ hand. He addressed the man directly. In an even voice with very little emotion, he said “I am not a hero. 112 people on my flight died. Please sit down.”
After the lights come up and the people drift away, I sat with Grace. It was very hard for her. I have little memory of the Burn ICU, but Grace had sat there all day, every day, for weeks. The cost was not abstract to her. Of all the people in the theater, she knew what the last moments of many of the 112 had looked like. After some time, we got up to walk out to the parking lot. As we went past the back of the theater, Captain Haynes was standing there with a few of the people from the stage crew. Grace went over to personally thank him for the evening. I stood about five feet away.
The 14 years had not been kind to Al Haynes. Both his son and wife had died. His daughter was terribly ill. I could not hear what he was saying softly to Grace, but he had the same look as he did in 1989. He was there, but detached. His story reminded me of a Greek Tragedy, no matter how noble his actions, fate struck people in his care.
A different man might have written it all off. Given up, and assigned the events to bad luck, a curse or even a vengeful God. I don’t think it is too much to say that Al Haynes would have none of these outs. He is a man, Naval Aviator and Airline Captain. He has a lifetime of being in command, evaluating the circumstance, minimizing the risk, and taking responsibility for the outcome. Such a man couldn’t easily shrug off or rationalize away the loss. Right or wrong, he is the kind of man who would only see it as his personal responsibility, and this is the reason I will always be able to say Al Haynes is my hero.
*Speaking of Courage is the title of a chapter in Tim O’Brien’s 1990 novel “The Things They Carried.” The writing is an unflinching look at sorrow, love and personal responsibility in the wake of tragedy. It is a profoundly moving work of philosophy for people who do not trust easy answers to hard questions.
Friday Night, November 20, 2009
Just as I am getting used to Daylight Savings stealing an hour of the evening, the days are getting noticeably shorter here. During the week, our clock revolves around 4 p.m. This is last call to drive the ten miles into town to the Post Office with the days mailings. In the summer there are hours after this to eat dinner, mess around in the shop, and casually pre-flight the Taylorcraft before going aloft for the last hour of light. But now the casual hours are gone. I drove back to the airport with an eye on the low angle of the sun, maybe only 50 minutes until it sank.
I pushed the plane out to the edge of the runway. I stood there for a minute, not a single person was in sight. Just the sound of a circular saw from somewhere up on the North end of the field. The visibility was poor, there would be little to see, but I had been out the past 6 days in a row and today would make a week. Kind of a pointless exercise, going up for 20 minutes to round out a week, frivolous really. These are the things you think of on the ground, by the time I am running through the mag check the pros and cons of going aloft are forgotten. I orbit the airport in big slow circles at 70 mph, engine at 1700 rpm, just licking over. It all looks gray and colorless. Was it noticeably greener a week ago or is it just the haze setting the mood?
When I touch down, the landing gives me the same feeling as finishing a chapter in a captivating book: Looking up from the last page with the powerful feeling that you have just been somewhere else. Taxing up to the house and shutting off the engine I have the same sensation.
Three or four minutes later, our EAA chapter president returns from being away all afternoon. A 180 mph pass at 10 feet signals the arrival of his RV-7. As he flies the landing pattern, I walk the 400 feet up to his hangar. We arrive at the same time. He has an unexpected passenger, Dave, our airpark president. Dave has his own RV-4, and I have never seen him as a passenger in any plane. In his youth he flew an A-4 from the USS Forestal into the most fiercely defended airspace on the planet. The black and white photos of him in his hangar are of a much younger man in a flightsuit with a helmet under his arm. He has the same grin today, but you get the impression that big chunk of Dave’s youth, and a good number of his friends, only exist in his memory after 1967. Either way, he looks really out of place in the right seat, or in any side by side aircraft for that matter.
The moment fits the gray haze: Pat and Dave have just returned after delivering the RV-9 of a fellow EAA member. This man has also taken up residence in Dave’s memory. He was killed this summer, along with another friend, in an unexplained Glasair crash. One moment they were flying a low pass over our airport, a little dog leg to say hello on their way home. The next day Pat found the wreckage in the woods a few miles away. They delivered the RV-9 to the man’s widow, who was very thankful. The plane was just finished, and it is magnificent. She is keeping it in storage until next Oshkosh. The man was an EAA member for 30 years, known in some circles. She would like it judged posthumously. She had said some moving things to Pat and Dave, but at the moment we were standing out on their ramp with the sun fading, neither of them felt up to relating her exact words.
Dave started a sentence twice, but after a pause he didn’t finish. Pat spoke about a guy he knew in flight school, lived 3 doors down, a Marine. Pat heard about his crash on the news, and walked out his front door in disbelief. Seeing the black cars gathered down the block took away the doubt and hope at the same time.
An engine starts at the far south end of the runway. It is Dan Weseman and the Cleanex. After a minute of run up, he roars past us, 50 feet at midfield. Dave looks at Pat and says “Let’s get him.” The RV-7 turned around and back on the grass in seconds. Dave pushes out his RV-4. Their take off alerts the airport, and several people drift out of their hangars to sit on the grass and watch.
If flying at most airports is an elegant ballet, flying at our airport is Mixed Martial Arts. The furball is formed, broken and formed again over our heads at 1500′. Between the sounds of wide open engines, the radio chatter barks out from the base station in Alan’s hangar. In minutes they are joined by Bob in an RV-4 from the North end, and then another RV-7. In the sky they turn impossibly tight. You can’t always make out who is on top, or even who is who, until a glint of the sunset differentiates a painted wing from a polished one. It is hard to believe that the same airport was dead silent 20 minutes ago.
One by one, they drop out and land. Pat is first, and has most of a beer finished as Dave rolls up. Bob is the last to break off, leaving it where it started, with Dan alone in the sky doing a few last slow rolls. The mood is transformed. It was 10 minutes of really being alive. Dan landed, rolled out in front of us, turned a smooth 180 and taxied back towards his hangar, his home, his family. He was close enough for us to see his expression, but he didn’t look over. In the air, he had been far closer to the other pilots. The light is gone now, and the day is over.
A few more words, and the hangar doors are shut, and people drift away. Walking back to my place, I pause in the dark to watch Dave walk out to his pickup. He had been the one to say “Let’s get him.” This had been Dave’s doing, perhaps his ritual. A little farewell to a man whose memory had just been carefully and lovingly wrapped up for safe keeping. It was now stored beside the others. A resident, final age 58, joining a group of younger men, some of whom arrived 42 years ago. Although I’m sure he cherishes them all, he probably doesn’t visit with them often. Dave is too full of life for much of that. Besides, one day he will have all the time in the world to spend with them.
Big news on Scottie Blankenship’s Corvair-powered Highlander: on January 10th, at the Just Aircraft factory (where Scottie works), he ran his Roy-bearing engine for the first time — on the airplane. It fired right up, and the wonderful sound and smoothness of the Corvair dazzled a lot of people.
Scottie still has a little work to finish up the airframe, but the first Corvair-powered Highlander will be in the air soon.
My 3-liter engine is at Roy’s now, and I expect the engine and I will be at his next hosting of the Corvair College. Though my Highlander is still well behind Scottie’s, I’m building every day, so I’m making steady progress.
The blog is a fine idea. Thanks for your continued good work.
DO YOU KNOW YET, WHERE YOU WILL BE RECOMMENDING THESE NEW HIGH VOLUME OIL PUMPS BE USED?
Flying Zenith 601 with 2,700 cc Corvair, Corvair Colleges alumni
This pump is only recommended to builders using a Weseman bearing. Roy tends to use stock pumps with his bearing. Send us an updated flight report on your airplane and some fresh photos when you have a chance.
William, I’m no guru, but oil is a subject mechanics really toss about. I’ve heard a million reasons for or against a certain oil, oil pressure, volume, SAE grade, etc. I sold Amzoil for about 2 years and my hardest sell was to aircraft mechanics. I knew it was tough as nails oil, and it could really take the punishment of aircraft engines. I ran it in everything, cars, boats, motorcycles, and I could not convince the aircraft owner to put it into aircraft applications. I think that opinions are like noses, everyone has one. Aero Shell was what they wanted, and they were not to be swayed. Shell is a very good lube, but I think Amzoil is a tougher product.
Perhaps the fact that they are more armchair quarterbacks, than actual pilots who assess the real life issues facing piloting a homebuilt. Besides, this heavy duty oil pump was accepted and ok’d by Scoob E. That’s enough for me. William be well.
Thanks for your comments. As you’re an airline mechanic, I hold your opinion in high regard. We flew a lot of hours on Amsoil and it works great in a Corvair. I want to caution builders to NEVER use Aeroshell in a Corvair. It has no zinc phosphate in it, a required element that is protecting the cam and lifters in a Corvair. Our favorite oil remains Shell Rotella T 15W40.
William, I enjoy reading your writings, philosophy and about your experience. I feel and work very much on the same principal as you, and relate to your philosophy because I feel we are driven by the same things, and also our need to learn how and why. You are doing an excellent job of getting the word out on your work, and I while I am still in the early stages of learning about and building my Corvair conversion, the more I learn, the more I know I have made the right decision for me and my project. Vic Delgado
Thanks for your kind words. I write the stuff from the heart. It doesn’t resonate with everybody, but the style is honest and a number of people, like yourself, appreciate it as an addition to the technical expertise. Keep us posted on your progress.
Is this the same high volume pump I saw at the last College in November? I wasn’t that familiar will all of the parts but I thought I saw a machined deep case like the one in the picture at your table along with the carbs. It was a nicely machined piece.
Gary Burdett, 2,850 cc CH 750 builder, CC #21 alumni
Yes, we had the prototypes at CC #21. The Colleges are often the first places we display new ideas.
Brian Manlove, heading to CC #22, comments on High Volume Oil Pumps:
Mom’s Singer sewing machine, circa 1956. I was 4. Totally disassembled. She said I got screws loose that she could never budge. She promptly bought me a nice Erector Set… Which lasted until the lawn mower a few years later…
This is a great site. Thank you for taking the time to put it all together.
I read through this article on the balancer with interest. I really appreciate the pictures and your detailed explanation. This gives me a much better picture of what is going on, on that end of the engine. My balancer is stock that came with the engine. I had thought of using it but I am now having second thoughts and will probably replace it with a rebuilt. Is there a good way of telling if the balancer is good?
Thanks for your coments. My New Year’s Resolution this year was to swear off watching anything on a television set. As a positive substitute, I’ve been working on our aircraft a little bit and reading a lot more. I just picked up a copy of Laura Hillenbrand’s New York Times Best Seller “Unbroken,” the World War II biogroaphy of Louis Zamperini. Chapter 8 starts with describing a B-24 mission out of Hawaii on January 8, 1943. I believe it is describing your father and his crew. The note is a few brief paragraphs, but I’m sure it will be of interest to you. it
On your balancer, if the rubber is extruded above the surface of the metal, I would not trust it. Rebuilt balancers have a eurethane type material in place of the rubber. Dale Balancers have a four-digit serial number stamped on them and two witness marks to align the inner and outter part. If you have one of these, it is good to fly.
The billet crank, for the reasons stated, looks like a very promising approach. The methodical and careful approach to R&D is what impresses. At the same time I can appreciate that the standard 164 Corvair is more than adequate for an airplane such as the Pietenpol that I’ve started on.
The best evidence we have available suggests you’re right. If someone wanted to use a billet crank in a Pietenpol, I’m all for it. If someone chooses to fly another aircraft on a stock crank, I’m all for that as well. As I stated in the post, I’m here to present the data as we know it and let each builder decide for himself what makes sense on his own aircraft.
William, Thanks for your responses regarding my motor mount. I am still practicing my gas welding technique. It has to be good if I’m going to attempt to tack-weld to a spool on a wood table top!
On another note, I was wondering if you could comment/report on the status of the turbo set-up. Even though I am 90% set on the 3L option for the heavier Rebel (about 925 lbs. empty), turbo normalizing on a bush plane seems like a good match (max take-off power even at high density altitude, etc….). Roy hasn’t even started on my 3L conversion yet, so it’s not too late to change my mind.
Rob Schaum, Murphy Rebel
Here’s the good news: A 3 Liter engine has the dished pistons in it which allow later turbocharging should you choose to upgrade to that. We had very good results testing the compatiibility of turbos and OT-10 cams. There are a few small changes to turbocharging an engine, but they are all external on a 3L. Anyone building a 2,850 or a 3L engine is in a good position to upgrade to a turbo later if they choose to do so. It will not require changing anything internal on the engine.
Back in the day when I worked in a shop remanufacturing Allison transmissions we used TimeSerts. Never saw one fail. Did however see some Helicoils unravel during disassembly for whatever reason. Perhaps not adequately installed? But none I saw failed in operation, only disassembly.
(I am a mechanically inclined PP-SEL with some taildragger time; dedicated observer & fan but not a builder at this poin t- but /only/ because of present financial and time constraints. Have pretty firmly concluded that Corvair would be the best/only choice for me if/when I build. Kudos to William for his philosophy & zeal in encouraging this most sane of alternative engines!)
Dear Mr. Elk,
Thank you for the comments. The number one thing that helicoils and some time-serts have a problem with is having excessive carbon hanging out on the end of a sparkplug thread protruding past the helicoil into the cylinder. When such a plug is removed, the carbon will occasionally jam the threads and back out the helicoil. For this reason, I like time-serts in sparkplug holes on Corvairs more than helicoils. However, helicoils do a darn good job in places where the bolt will not be removed and replaced frequently.
Your new blog is the perfect forum for this kind of information sharing. It is so easy to get distracted by the noise and chatter of the online discussions that seem to attract strong (but often uninformed) opinions from self-proclaimed experts. I continue to appreciate your practical approach to helping builders follow a proven path to their first flight and beyond. Thanks, William. Now it’s back to the shop so I can see you in the air in 2012!
Larry Winger, California, CH 650 2700 cc/Weseman bearing, engine ran at CC #18
I thought you’d appreciate the photo above taken during the housecall I made to you after Corvair College #18. Keep us posted as you close in on your first flight.
Becky Shipman, 2,700cc CH 650 with Weseman bearing, comments on Chinese crankshafts:
Part of my job for a multinational corporation is to train Chinese engineers to maintain and operate coating equipment. It takes a while to get them to understand the importance of maintaining tight tolerances. I think I’ll go for an original GM crank nitrided.
The original GM crank nitrided with a fifth bearing is the most popular combination that people are building for their Zenith aircraft. Although there are a large number of 601/650s flying without a fifth bearing, many of these people plan to upgrade to a Weseman bearing. We recommend that everyone with a STOL airplane utilize a 5th bearing because they can generate large asymmetric loads at high angles of attack.
I concur with your evaluation of Chinese manufacturing. They are capable of making some excellent products, but quality control is not their strongest suit. Price is their strongest motivation, and, when they compete for business with other businesses in China, their margins are often paper thin.
China has a vastly higher number of engineers than we have here in the U.S., but in their move from what was basically a feudal, agrarian, society before the revolution, to a much more modern and still economically controlled society, there have been a number of shortcuts that have been taken. It shows up in quality.
It’s the wild west there. There are no standards and they don’t use W. Edwards Demings’ quality control principles in many of their products. Caveat emptor.
I read your comments with special interest, aware that your mother and father worked a great deal of their lives in mainland China before the revolution. Your international background, hailing from an American family working in China born in India, gives you a unique take.
Rick Lindstrom, contributing editor of Kit Planes Magazine, 2,700 cc 601 builder and pilot, comments on Chines Crankshafts:
Years ago I worked for a computer manufacturer that had our circuit boards built by relatives of the CEO in China. These boards were plagued with compatibility issues, and I headed up the service organization charged with making them operational. This is where I learned a lot about the Chinese philosophy of manufacturing. Two things still stick out.
The Chinese are VERY frugal, to the point of using a known incompatible component until it’s gone from inventory. The silk screened revision number might be correct, but the mix of parts on the board was anybody’s guess.
And they also have a common saying when dealing with westerners. It goes “You can ALWAYS fool the foreigner!” We think this is unethical. They think it’s good business practice.
I keep these two things in mind whenever I purchase anything. I’ll pay double or triple if I can avoid the serious quality issues inherent in Chinese hardware.
But, I still like Chinese food.
Thanks for your comments. We included the above photo with you in the center flanked by myself on the right and Michael Heintz after you won the Best Engine Installation Award at Copperstate in 2007. We also love Chinese food. Our local restaurant is owned by a family that emigrated from Kowloon. When you think about it, the food they make now is made in America.
Ron Lendon, 2,700 cc, Roy bearing equipped, CH 601, 1st engine run at CC #17, also writes about Chinese crankshafts:
Thanks for taking the time to provide a well thought response to the crank issue. Hopefully those who need to know this story will read and understand its full meaning.
Your thoughts on this carry some weight. The fact that you work for the engineering branch of General Motors and understand international manufacturing makes your recommendation noteworthy. Looking forward to seeing your airplane airborne this year.
Nice blog site! .. I’m very glad to see you back on the web with a Q&A forum that includes pics. It’ll be a great resource to builders and Corvair flyers alike. I just passed 80 hours last weekend on my Corvair-powered Zenith CH650 and the engine I built seems to produce even more power in the past 30 or so hours .. I assume that’s because it was finally breaking in? I have yet to re-pitch my Warp drive prop just yet as I’ve been enjoying flying too much on any nice weekends. At 3000 rpm I get 115 mph indicated on these chilly days here in Indiana .. and that’s at 8.5 degrees of pitch.
By the way, I firmly believe the Corvair engine is a perfect match for my home-built aircraft and delivers outstanding performance for an engine that I built and can maintain going forward. Thanks again for launching this site and the support you will provide here.
Regards, Dave Gardea, Flying Zenith 650
Great to hear from you. Thank you for the progress report. If you can e-mail us a few current photos, we’d like to do an aircraft update on your plane here like we did with Andy Elliott’s. A YouTube video link also would be greatly appreciated.
These valve covers look really nice. I wish mine were powdercoated, but I didn’t even think of that, back in the day.
I think this blog is a great idea. It looks like this will be a great forum to record your vast knowledge about all things Corvair.
Phil Maxson, 2,700 cc/Weseman bearing, Flying 601XL, New Jersey
I watched the YouTube video the other day of your airplane flying over Daytona Beach. It had 30,000 hits on it. You’re a movie star. Send us a few new photos and an update and we’ll write a Flying Planes post about you like Andy Elliott’s.
It’s great to have a single-point resource for open discussions on the Corvair conversion. Have been following “The Movement” for several years and am now building a CH650 which is slated for Corvair power when the time comes. However, I must say that my enthusiasm was curbed a bit after hearing of Mark’s crank failure but I remain optimistic that this conversion will continue to evolve into a reliable alternative power solution.
Thanks for all of the expertise and insight that you so generously share with the rest of us. Looking forward to following along with hopes of sharing something meaningful in the future.
Sonny Webster, Magnolia, TX
Thank you for the note. We’re going to cover a lot more of the successful flying Zenith aircraft, to give people a more rounded view of how many successful flying aircraft there are out there on Corvair power, particularly Zeniths. The notes above include 3 guys who are out there flying the Zenith/Corvair combination you’re building. Given all the data, most builders agree it’s an excellent combination. Hope to see you at CC #22.
Hi William & Grace I really like the new Corvair Communication Center, you all did an oustanding job setting it all up.
Thank You, Russ Mintkenbaugh Building Wagabond w/ Coravir Power, first engine run CC #20
Great to hear from you. We had a fanatastic time with you at Corvair College #21. Looking forward to seeing more of you this year. Keep up the good work on your project and please email us photos of your project.
Good to see you back, missed you over at Corvair list. Buttercup is sleeping nice and snug, hope to have shop room in a month. Looking forward to a CC at Roy’s place.
Joe Brown, Merrill, WI
Good to hear from you. I was just saying to Roy that the housecall we made to your place may very well have been the northernmost one I’ve ever made in the U.S. Good to hear that your plans for a shop are coming together. There are many people who would like to see you put the rest of our old Buttercup project together and demonstrate how well that combination will work. Please keep us posted on your progress with photos.
I would post some pictures of my Dragonfly/Corvair but I am not sure how to do that on this blog. I am not a blogger does one have to join a group or something?
Charlie Johnson, Ogden, Utah, 2,700 cc Corvair with Weseman bearing now in taxi testing, veteran of CCs # 13 and 21
Since you’re a real life rocket scientist, we would have figured you knew all about blogs. You do not have to join or subscribe, you can just come here and read and send us photos to our regular email address, WilliamTCA@aol.com. This blog has a notification feature that will let you know when we have something new on here if you click on the RSS link and subscribe. Looking forward to hearing of your first flight.
William, Good news is that you are doing this blog site. I feel like my principle information source is again available to me. My 2850 cc is mounted and waiting on me to finish up the remaining tasks of completing the the Sonex, such as wiring the panel and painting. Just a couple of more months! Clarence Dunkerley, Cleanex builder with running engine, CCs #19 & 21
Great to hear from you. Watching you and your brother work together at CC #21 to get your engine up and running was fun and inspirational. I got a message from Sensenich the other day, so I suspect your 54×56 prop is ready to go. Looking forward to seeing your bird in the air this year.
The following photo series is of testing a new High Volume Oil Pump that we had made. The assembly and testing covered about 5 hours on Friday night. When I was in my 20s, I used to make a point of donating 10% of my week’s pay to Anheuser-Busch corporation on Friday night. In the past 2 decades, I have found more productive things to do with weekends. Years ago, people saw how much time I spent at our old hangar and often said that I practically lived at the airport. After Grace and I were married, rather than trying to get me to come home from work earlier, she came up with the solution of moving the house closer to the hangar. For the past 6 years they have been 10 feet apart. Our hangar is 40’x50’, but I do most of the work in the adjoining 15’x30’ shop seen in the photos. Our hangar is a basic metal pole barn without insulation. The workshop is fully insulated and got an older central heat and A/C system installed last year. (We have a neighbor in the HVAC business who needed a Warp Drive prop.) Although we live on a little airport, working in the small shop next to the house gives me the same feeling I had when I first got started building planes in the garage behind my house at 1235 International Speedway Blvd., Daytona. Working in the shop makes me think about all the other builders out there working in their garages, basements and workshops, all the people enjoying the hours creating their plane with their own hands. No matter how diverse homebuilders are, they all have this in common.
Here is a shot of the basic unit. A high volume pump is basically a longer set of gears with some type of extended housing. The extended gears are from a small block Chevy V-8, and they are identical to a Corvair’s except they are .400” longer. The next time some brilliant guy in your EAA chapter tries to tell you that Porsche or Franklin designed the Corvair engine, you can ask him why he thinks the oil pump is interchangeable with a V-8. The Corvair is 100% Chevrolet engineering.
The extended housing on high volume pumps is usually a two piece affair that his held together with roll pins, it can be a little tricky to set up, and it does have some pumping losses from a less than perfect fit in the assembly alignment. It also has two gaskets in it. Above you can see that our housing is a one-piece bowl-shaped unit, CNC machined. Instead of aligning itself on roll pins, it centers itself on the two shafts, which are stabilized by the housing. This is not a new concept, this style had been made before by Corvair car racing guys. However, our unit was sized from scratch, and independently developed to serve aircraft guys. It is self aligning, has minimal pumping losses, and only has one gasket.
If you have been around Corvairs only a few years , this is a tool you may not have seen before. I built it many years ago to test oil systems. It is the back half of a Corvair case with a little sump added underneath. It has plugs welded in a lot of places to seal it, and the gauges are set to read oil pressure before and after the bypass. It has a valve to allow mimicking any bearing clearance and oil flow requirement. This part is actually a rare “RL” case from a 180hp turbo Corvair, but it is special for another reason: It flew several hundred hours in our Pietenpol. Over the years, we have tested many cases on this unit. After we moved to Gold Oil Filter Housings, we stopped working on rear oil cases for builders because most Gold Oil Systems use our replacement oil cooler bypass valve built into the Sandwich Adaptor. This unit was very good at detecting a marginal stock oil cooler bypass, in addition to testing oil pumps.
Over the years, I have made lots of pieces of custom testing equipment, because testing is the most important element that we do. Many people have an idea about making a part. If they have time and money, or they are amateur CAD guys, they can get a machine shop to make the part. Some of these will function, and a still smaller fraction will work with other required parts in a way that fits in the final installation. Some of these parts will actually pass basic testing. But the real testing requirement is not showing it will work, but aggressively trying to find the way the part, or under which circumstances, or in which combination it will not work. Few people understand that this is the real focus of testing. Most people who conceive of an idea, defend the concept, nurse it through manufacture, and then start testing it have a big emotional attachment to it. At that point, they believe in it. They have a very hard time trying to develop any test that will show the part or concept to be deficient or vulnerable. For testing to be of any real value, you have to run it as if it is being directed by your worst enemy, your ex-wife and her mother, and the guy at work who thinks homebuilt aircraft are crazy. For the period of testing, you have to pretend that these people have PhDs from MIT and Cal-Tech, and they want to find any flaw in your idea. You have to really let go of any emotional attachment to the concept’s success. This is really what running an effective test is all about.
Adhering to this over the years, we have tested a lot of ideas that never saw the light of day. All of the things we do make were refined by the process I just outlined. Our evolution in the development of the engine and installations was never hampered by an emotional attachment to the way we were doing it. Once a month or so, I will get a guy on the phone who will say something like “well you used to do it that way” referring to the set-up he is planning on using in his plane. He saw in an old photo on our Web page, and is yet to understand why it evolved. His attachment is understandable, it’s how we did it once, and he doesn’t see the forces that drove the evolution. I talk a lot, but I am also a very keen listener, and in the conversation I can hear if they guy has an emotional attachment to the old way, and if he is resistant to the logical reasons why it evolved. You don’t have to build your Corvair the way we do, but when evaluating your choices, be very cognizant of the emotional attachment factor creeping in and not letting you truly evaluate the merits. Homebuilders by their very nature arrive in the field wanting to do something different. They are reluctant to be seen as conformists. This is a good concept, but it can also work against the practical goal of completing the plane. If 10 new guys all look at the logic of why we build engines the way we do, evaluate it, and then choose to build their engines that way, this is not a sign of conformity, this is critical thinking leading many people to the same point. There will always be some guy on the Net who criticizes this and tells everyone how his engine is going to be totally different, that is once he gets started building it. 20+ years of working with homebuilders has taught me that the odds of that person flying anything are microscopic. But it isn’t primarily because his idea is bad, actually the Achilles heel of his whole concept is that It is emotionally driven by a force that has very little sustenance in it, the concern for what other people think of you.
In the background, a selection of oil pump gaskets in different thicknesses. This is how Corvairs set the pump clearance. After test fitting them, and checking for a slight drag on the pump while turning it, I settle on a .007” thick gasket and give it a light coat of spray copper before sealing it up.
Here is the unit all buttoned up, Yes, I ate dinner at the workbench.
The drill bit is pointing to the pressure regulator bypass hole. It has to be opened up when you install a high volume pump. Otherwise the pressure will be very high until the oil temp is thoroughly warmed up. The enlarged hole allows the bypass to work with cold thick oil. Without enlarging this hole it might take 15 minutes of running on the ground on a 40 F day before the oil settled down to its normal regulated pressure. Before this, an increase in rpm will raise the oil pressure. On very cold start ups you want to watch this, because even with the hole enlarged it is possible to have the oil pressure exceed 80 pounds by carelessly revving the engine to taxi it while the oil is still cold. Give the engine a chance to warm up, don’t be in a rush. Oil pressure spikes are very rough on the drive system running the pump. This is true of almost all engines, not just Corvairs. People don’t talk about ideas like this with the buy-it-in–a-box imported engines because they just wanted to buy something and use it. Since the primary motivation with Corvair builders is to learn while creating, we talk about things. Most people are happy to just have things, people attracted to the Corvair were the ones who took apart the toaster at age 10, because for some of us, we need to know why.
This plug holds in the spring and the pressure regulation piston. Make sure your piston is polished and the bore has no burrs left over from enlarging the hole. I use a copper crush washer for the gasket. I use the higher pressure spring from Clark’s. The wrench size is 13/16” but it has small fine threads, so don’t do more than 15 foot pounds or so. I do not safety these, and I have never seen one get loose. This plug is shiny because I nickel plate them.
Above is the unit in action. It is being driven by an electric drill on a priming shaft, just the way we prime the engines at the Collegesbefore we run them. After running through the system, the oil is returned to the center of the case by the 3/8” aluminum hard line on the right; it is entering the case where the #1 cylinder was. Notice that you can actually see the oil stream flowing in the photo. From there it goes back in the bottom of the case and is sucked into the pickup again. The new pump flowed like a river, even at very low rpm. We are going to let it run for a long time in the shop this weekend, with the drill trigger held down with a zip tie. It will be noisy, but I have my sister’s old 1970s stereo that she bought with babysitting money in the shop, a hold over from when people cared about sound. 120 watts, Ohlm speakers and an extended cut version of Exile on Main Street and I will never notice the sound of the oil pump rig running all weekend. Monday we will take it apart and look for any wear on the inside.
Grace and Scoob E were out in the shop helping with the project. Above, Grace ran the drill during the set up tests. This rear cover will have a Gold Oil Housing on it when it is finalized, but for testing, I have it set up with one of our old style oil top plates from the 2004-2007 era. You can see the built-in pressure gauges in this photo.
It wouldn’t be Friday night without a little fun. Our neighbor Roger was having a cookout and a bonfire in his front yard just down the runway. We missed dinner, but arrived in time for the relaxing around the fire with a beer phase. Most builders know that the one pound cooling fan on a late model Corvair car is made of magnesium. We brought one down and after warning those present, tossed it in the fire. It ignited after a minute of warming up. For five minutes you could have seen our airport from low earth orbit. The camera doesn’t do the event justice. It illuminated the entire southern end of the airport; you could have read a newspaper 500’ away. At most airports this would have brought firefighters, hazmat people and the news media. At our airport it brought more people with beer. As a little kid, I played with matches, built tree houses, took apart the toaster, made go-carts and was known on a first name basis at the emergency room. My test methods have gotten a lot better than childhood forays into chemistry, but my incessant need to know remains the same. I accept that the majority of people in life have a consumer mentality that tells them that simple possession is the route to happiness. For the rest of us who know that our path to happiness is learning and creating, we have the Corvair movement. The Harley Davidson slogan, “If you have to ask, you wouldn’t understand”’ is a modern version of George Mallory saying “Because it’s there” about mountaineering. The first statement has become something of a cliché, and many of the people saying it are concerned with what others think, but Mallory was deadly serious that he was not going to lead his life by the mundane concerns of others. My mother taught us to be civil to everyone, but even as kids, there was a clear distinction between always being considerate of others, and leading your life by what other people think. It was an important inoculation that protected me, especially in my teenage years, from peer pressure and the things it leads adolescents to. In the long run, it made me comfortable following my own path, with little concern for what the larger group thought I should be doing. The Corvair movement is a reflection of this, and if you feel the same way, I say “Welcome aboard.”
Dan Weseman, the man behind the Wicked Cleanex, The BTA 5th bearing, and the Panther project, the second winner of the Cherry Grove Trophy, is working his way toward a new goal is the land of Corvair powered flight. He is developing a made in the USA, true billet crank for Corvair flight engines. Follow this post and get an inside take on his motivation and the challenges involved.
Above, Dan in his new 12’x50′ climate controlled workshop built inside his hangar. He built the space to facilitate the development of and the eventual production of “Florida Panther” aircraft. In the photo are a fuselage side for the steel tube sub frame and an aluminum wing rib. Although the plane is intended to be an LSA legal, fun flying plane, Dan is building in enough strength for some advanced aerobatic work.
Dan Weseman has a well earned reputation in the world of flying Corvairs as a get it done kind of guy. Outside of aviation, people are impressed by people who get a lot done in a day. Inside aviation, accomplishments are done on a longer time scale. Building a plane has an element of “What can you get done in the next 4 hours?” to it that is very important. But it also has the requirement of stringing together a long series of these work sessions. Lasting accomplishments are built of this type of sustained efforts.
Dan often takes a modest tone on the outside, saying things like “we will see how this works” in discussing projects, but knowing him for many years, I have come to see that such comments are really to keep discussion low, and they address the fact that many new arrivals in experimental aviation are yet to see the sustained effort required to bring anything good to physical reality. Downplaying the discussion side of his efforts is a way that keeps Dan operating the project on his schedule, not on anyone elese’s expectation.
This has proven to work well in the long run. Dan, in joint effort with his father Jim, have now delivered more than 200 of their 5th bearings to Corvair builders. The bearing story is one of careful development and testing followed by steady customer support. Same goes for Dan’s efforts making “Cleanex” Corvair installation packages available to people building Sonex airframes. After building and flying his own aircraft and refining the installation, Dan moved to making the parts available. His installation components are compatible with all of our engine components. We even developed some parts, like the Reverse Gold Oil Filter Housing and the Universal #1 Exhaust specifically for Cleanex installations. The engine installation has been a steady success story. When I visited Dan’s shop there were 5 more Cleanex mounts in process being finished by master welder Vernon Stevenson.
Dan is now turning this approach to the subject of billet crankshafts. While other people have thought of this before, and Corvair race car guys have had a handful of them made by crank specialty shops over the years, they have not shown up in experimental aircraft. Here is where Dan’s unique background comes in. For a day job, he installs CNC machining equipment in industrial production shops in the southeastern U.S. His company deals with the transportation and installation, so he gets to work with all types and brands of machinery. He has been inside more machine shops than any other person I have ever met. He fully understands which type of modern equipment is best suited for making a run of billet cranks for high stress Corvair engines. Combine this with his background as a builder and a flyer, and the experience he has in bringing parts to the market and supporting them, and you have the makings of a success story.
A billet crank is made from a piece of round stock, typically in the case of the Corvair, a cylinder 6″ in diameter and two feet long. This material is most often 4340 alloy steel made under exacting conditions. This cylinder itself is a forged piece of material, not cast. Professional race car engine builders specify that these blanks be made in the U.S. with a paperwork trail that demonstrates their pedigree. Because 80% of the material in the blank is going to be removed to make the crank, it must be guaranteed to be homogeneous throughout the blank.
Hand making these cranks in a crankshaft shop is one of the reasons why they typically cost $3000. The material removal takes a long time on traditional equipment. Many crankshaft shops only have the reserve manpower to make a few of these a year. Dan is looking into a different approach, where he is going to have 98% of the material removed by very powerful CNC equipment, bar feeding lathes that can work from a 20 foot long billet. As a second step he wants to take them in groups to a crankshaft specific shop like Moldex, where those craftsmen will be able to put the finish grind and balance on the part. He is working toward driving down the price toward $2000-$2500 with a new gear installed.
Such a crankshaft can be made stronger than the original GM forged crank. Contrary to what many people think, billet cranks are not inherently stronger than forged ones. The grain of a forged crank actually makes it stronger than a billet in direct comparison. However, automotive cranks do not have large radiuses in the fillets. In cars they are not required. Purpose built aircraft cranks have much larger radiuses, reducing the potential for a stress riser. Billet cranks can be built with large radiuses, and this allows them to potentially withstand extreme forces better than a forged crank with smaller radiuses. At times, discussion on crankshafts is driven by people who don’t have a grasp on concepts like this. Productive understanding starts with a practical look at how the concepts are applied to our specific engine. Commentary without this isn’t worth serious consideration. People will always throw around statements like “they are 20% stronger.” No statement like that makes sense without addressing tension, torsion, bending or fatigue life. The real discussion is a far greater in depth, while focused on a far narrower scope.
A number of people think that the genesis of Dan’s billet crank project was when Mark Langford broke the back end of his KR-2s crank in November. In reality, Dan had long been planning on having a billet crank as an experiment in his new aircraft, the Panther. In his own style of letting the project set the timetable, not public discussion, he was working quietly on the topic, developing the plan as he worked in a number of different CNC shops that have the equipment that would make the project economically viable. After Mark’s comments, some builders started asking about billet cranks, including Chinese ones. In an effort to let people know that he was working on a U.S. made one, Dan mentioned this, and has a small email list of people who are following his progress. Mark Langford is one of the people who has said he will use one of Dan’s cranks in the next incarnation of his engine. To be clear, Dan’s interest in the development was driven by the fact that he is going to set up his personal Panther for some very hardcore aerobatics. He has told me he wants to use the Precision mechanical fuel injection we have for testing, and he is even considering an inverted oil system. In his 3,100cc Cleanex, Dan flew a tremendous amount of sportsman aerobatics on a stock GM crank. He did a lot of this without a 5th bearing. After he developed his bearing he retrofitted it on the same engine/crank and kept going. Over several hundred hours of hard flying he has not had a crank issue with either the nitrided crank by itself nor his 5th bearing. When it comes to flying like that, most people recognize that it makes sense to have a 5th bearing. Likewise, now that Dan is moving up a notch in the stress department, going to a large radius billet crank is just part of his plan to make sure that he has 200% of the strength he needs, not 99%.
The most common question that people have about these cranks is “Do I need one?” My primary answer for this is that the vast majority of builders do not need one of these. That is my opinion based on the big picture of statistical evidence we have from being at the center of the Corvair movement. I have seen Dan fly hard aerobatics at wide open throttle in his Cleanex for 30 minutes at a time on a stock GM crank. We have pilots like Andy Elliot who have flown hundreds of hours on a 3,100 without a 5th bearing. Mark Petz overhauled the engine in Bernard Pietenpol’s Last Original last summer. It had 800 hours and the crank was perfect, in spite of never having been nitrided and not having a 5th bearing. We have a lot of pilots with several hundred hours on non-nitrided cranks and no 5th bearings. It is all a matter of personal choice. Very seriously, I am not, and do not wish to be, in charge of anyone eles’s building, flying or life. The primary attraction to me of flying is freedom, and the root of this is being able to decide things for myself. I am not here to take that away from anyone. I take presenting the facts very seriously. I take countering disinformation seriously. I take the task of explaining the risks very seriously. I want builders to know the big picture. But I fundamentally trust that anyone who is rational enough to fly a plane can make the correct decision for themselves, given factual, accurate information presented without emotion. If I came out and said, you have to have a nitrided crank, a 5th bearing, or a billet crank, or I will not work with you, then I am dictating that our accumulated knowledge will only be shared with some people. I make strong recommendations, demonstrate that I believe in these recommendations by building engines that match them and flying behind them. But, in the final measure, builders are going to make their own decisions.
New people will often say, “Just tell me what to do” in homebuilding. This is ok when you’re getting started in homebuilding. Most of these people get off to a good start by replicating the engines that we build in our shop. Over time, this same person needs to transition to the mindset where they are analyzing the available information and making the decision for themselves. I want builders over time to understand the logic of all of the choices we make in our work. They are not required to agree with the choice, but it is not a sign of conformity if two people look at a set of facts and come to the same conclusion. Making choices for yourself is what being in command is all about. This is how you prepare for being aloft, especially with another person in your plane. It is the great reward of flying. Self reliance and earned self confidence also happen to be your best line of defense in any flying situation.
In modern life, people are less and less in charge of important decisions that count. On many fronts, society is trying to prevent you from hurting yourself, and the method they choose is most often taking away the ability to do so, not educating you and letting you choose the path. Flying, and homebuilding in particular, is the polar opposite of this. You have to have a really negative view of individuals to buy into a system that tries to prevent people from having the means to hurt themselves…The queen and the hive dictate to the worker bee his limited task, and when he has fulfilled it, he is no longer of any common good, and he is expected to die quietly because the hive programmed him to do so… In my book, humans are individuals, not insects. Any person who chooses do something simply because he wants to is affirming this. Any person who picks up a tool and sets out on a journey to create something of his choosing, a goal that does not serve the hive of society, can expect both the disdain of the hive and the warm welcome of other individuals.