Fuel Injected Corvairs

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.

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Friends,

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.

Thank you,

William

Deland Showcase, CC #45, Nov. 14.

Builders,

Here is the video notice for Corvair College #45. Please note that this College is an “Operations College” Where the focus of the event is learning the subjects in the New – M.O.P. Manual, a required technical document.

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The event is open to the public, you only need to buy a gate pass for the whole Showcase event, you can learn all about this great hands on, aviation event, based on participation, not on spectating. Here is their info:

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https://www.sportaviationshowcase.com/event-info/index

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Above, the intro Video: Notice I’m wearing spiffy new “Polo Mafia” shirt provided by Larry Nelson.

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In addition to all of the “M.O.P.” information at CC #45, you can:

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Come and see Corvair Powered planes like Phil Maxson’s 601XL and The SPA Panther.

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Meet Corvair Builder/Pilots like Phil Maxson,   Ken Pavlou, and Paul Salter (You can even see verbal sparing matches between Ford Man and ‘Old Hairy Guy’. )

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You can bring all your core parts or assemblies, and I will carefully inspect them. If you like I can bring them back to my hangar or SPA’s shop for reconditioning.

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You can study a running 3,000cc Corvair on my run stand, learn regular maintenance items like distributor installation and prop pitch setting. We will also be demonstrating “Corvair Fast Burn” Ignition timing settings and how air-fuel meters work.

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Have any question answered in a friendly setting, were we will have the resources right on hand to make sure you really understand your power plant.

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Make plans today, It will great event, we are planning on packing a lot into the day, don’t miss it.

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WW.

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PS, if you have further questions about the event, please ask them here in the comments section, or call me direct at 904-806-8143.

 

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Night Run: Carb and Intake testing

Builders,

A quick look at Sunday night, outside my hangar. Dan Weseman was looking for an intake design and a Carb orientation and model, specifically for Corvair powered Panthers with tricycle gear. Tonight was the test run, and it turned out amazingly good.

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Above, a look at the back of my test stand; Notice it is now sporting two lab grade 5 wire O2 driven Air/Fuel meters.  The test question was essentially this: If a Rotec TBI is turned 90 decrees, will it still have excellent mixture distribution to both sides of the engine. The answer is yes. This was the largest spread under power, .3 on the air/fuel ration. That is as good as carbureted engines get.

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Above, Dan runs the controls.

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Above, a look at the Rotec on the manifold. It started and ran exceptionally well.

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After tests, Dan Rachel and I ate dinner at their place and talked about a lot of stuff, ranging from airport business to the new “Ford vs Ferrari” movie. It was a real nice end to a productive weekend.

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ww.

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Two very different Outcomes: Choose your own path.

Builders,

Here are two polar opposite stories, two builders of Corvair powered planes, who had radically different outcomes on their first flight this week. The difference in outcomes is solely attributable to decisions the builders made. If you disagree, and  think the difference is that some people are ‘lucky’, let me strongly urge you to get out of aviation, now while you are still ok.

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Success: Andy Mechling’s 3.0L Corvair powered Zenith 750 Cruiser. 

Andy called Dan and gave him a run down on the first two flights, both went very well, and he was showing real performance numbers like 110+ mph as a cruise setting with no wheel pats, larger tires and a climb prop setting. Engine was cool with a STOL Bowl , and everything is going very well. Satisfied builder at the beginning of many fine adventures.

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Above: Get a good look at Andy’s expression the minute his engine fired up on the run stand at a 2016 finishing School we held at SPA. Read the full story here: Zenith 750 engine; Andy Mechling’s 3,000cc/120HP Corvair

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XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

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Not Success: Pietenpol completed by a man who elected not to talk with me about his project crashes on its first ‘flight’:

https://www.nbc4i.com/news/local-news/plane-crash-reported-in-heath/

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First, let me say I’m very thankful that the guy wasn’t seriously hurt or killed. The investigators today said he was doused in fuel, and it was something of a miracle he wasn’t killed. Much of the following info I share isn’t speculation, it is from the actual investigators. Additionally, the first flight was captured on video,a more reliable source than personal recollections.

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On June 20th, I wrote the following story on my blog, and yes this is the same aircraft: Need Help Contacting the Builder of this Aircraft ASAP. I wrote it because I was interested in speaking with the builder before he went flying and something went wrong. He contacted me the next day, and said I have to take his airplanes picture off my site, and off FB, as it was ‘Copywritten’ I wasn’t into debating it, my goal was to get him to reconsider some things I saw, even though he was not a builder of mine, and he never bought anything from me. The guy who sold him the project told him it was a WW conversion, it wasn’t, I didn’t care, just wanted to start a conversation with the guy to get him to reconsider some stuff. He wasn’t belligerent, but he wasn’t interested in talking. I’m a very serious respecter of personal choice, and it was his absolute right to make that decision. In the last few days some people on the net, with an axe to grind, have implied that no one tried to assist this man. That is complete BS, I did.

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The plane tried to take off from a 4,900′ paved runway. That is at least ten times longer than a Pietenpol would need to get airborne from. It never gaining tree top altitude, but the pilot apparently never pulled the power back.  The plane flew another 1/2 mile, was not going to clear a line of trees, and the pilot tried landing in a rough field. The planes wing was completely displaced on contact with the ground, the fuel tank ruptured, and the plane was destroyed.

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I have no idea if he read this 2016 story, but there is a reason why I selected it as story topic number one in the series.Critical Understanding #1, Take off distance.. If a pilot didn’t want to have this accident, all he had to do was pull the throttle back when he passed say 800′ and was still on the ground. Anyone who has seen Corvair powered Pietenpols taking off at Brodhead can see they only need 300-500′ for a modest regular takeoff. Still holding the throttle in thousands of feet down the runway isn’t a mechanical problem, it is a judgement error.  Any pilot, in any plane, who pushes the throttle forward without knowing his exact abort point on the runway, is making a judgement error, even if he never has an issue. The error is starting a takeoff with no plan. If you have been around homebuilding for a number of years, it is stunning how often this becomes a ‘first flight’ accident.

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If you have not seen the series, they are all listed right here: Critical Understanding Reference Page. My commitment to assisting builders starts with the things I write and teach. It extends all the way to trying to contact people who are not even customers of mine.

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The investigators mentioned that the plane likely had a home made prop on it, and that it never made full static rpm. I addressed both of these issues in this story: Critical Understanding #2, Absolute Minimum Static RPM.,  spelling out that no Corvair powered plane should ever be flown with less than 2700 static rpm.  Let me be very clear, it obviously wasn’t making anywhere near the level of thrust that even a very modest running Corvair turning a factory made prop would have. Included in the story is this sentence:

“No offense to any builder who wants to make his own Piet prop, but you have to look at what you are getting over a Warp Drive prop besides looks”

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I’m going to spell this out for new people: I could put a 66″ long 2 x 6 on the front of a Corvair and it would turn 2700 static rpm, but it would make Zero thrust, it would not even allow the plane to taxi at 2 mph. That is a ‘safe’ home made prop. I could put a 66″long Warp Drive prop on the same plane and it would 2700 rpm, and fly great, because it would make about 400 pounds of thrust. The trouble with many home made or small company props is they may make the required rpm, but that is no indication what so ever that they make enough thrust. They may make just enough to get the plane in trouble. I have written countless stories about this, like this one: Critical Understanding #3, Rate of Climb, the critical prop evaluation., and I genuinely hope the next guy flying a Corvair powered plane reads them, takes them to heart, and acts accordingly.

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ww.

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PS, if anyone is tempted to use the comments section here to say anything about the Piet pilot, Other than “I hope he fully recovers” , please don’t. The event has happened and nothing will change that now. The story here isn’t about one man’s mishap, its about making sure that your own personal first flight goes just like Andy Mechling’s. And that outcome solely depends on decisions you will make. 

 

Pietenpol Weight and Balance; Inputs for configuration calculation.

Builders,

If you are one of the Pietenpol builders who picked up a copy of our new Pietenpol Weight and Balance manual ,, and you would like to send in your data so we can assist you in getting your wing and landing gear into optimized locations, here is the information I will need:

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(A) The type of engine and the proposed propeller.

Ie: ” Ford with wood prop” or Continental 65, hand prop , Wood Prop” Or Corvair with a Warp Drive” Or “O-200 with electric start and a metal prop”

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(B) Length Of fuselage.

Long or Short (IMHO, no one should build a short fuselage plane if they are just starting. It has no advantages. )

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(C) The Pilots’s weight.

Your weight, dressed in a jacket, with headset, ready to fly. It also helps to know the pilots height, as the CG of a  5’6″ 200lb guy is a bit forward of a 6’4″ 200lb guy

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(D) The range of pilots weights

If you have friends who will test fly or likely be trusted to fly your plane, this important, and the most Piets can be set up to cover a 120–150 pound range of pilots.  So let me know if you are one of the lightest or one of the heaviest people who will fly the plane. Consider if you will have a kid or grandkid who might fly it when they are in the 120-130lb range.

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(E) Fuel Tank Location(s) and capacities.

Let me know where the fuel tank is, and what capacity it is. If the tank is in the fuselage, please reference its location in inches from the firewall. If you have a 12 gallon fuselage tank, and it is 16″ long, send me a note saying something like “12 gallons, with the center of the tank 9″ aft of the front face of the firewall.”

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(F) Unusual features: 

A full plywood fuselage; A glove box with a capacity of more than 8 pounds; Unusually heavy or different tailwheel and spring arrangements; Super light covering like Oratec; Pilots seat back location tilted more than 1.5″ from where the plans show. Please note these differences.

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Where do you  send (A) though (F)? 

I would greatly prefer if builders send the information right to the comments section here. If you send the information to the comments, in a few days I will come back with a specific recommendation.

If you are a bit concerned about sending your actual weight out on the internet because Cameron Diaz haunts your profile page on Match.com where you shaved 20 pounds off the actual number, and now you don’t want to get busted and have it ruin her image of you as a scrupulously honest character, no worries, I understand completely. Just send the info with your initials, and when she calls me with her suspicions, I’ll totally deny it’s you.  Thank me later, it just the kind of guy I am.

Seriously, don’t send in ‘optimistic’ numbers, the subject is a little too serious for vanity to show up in your numbers. Over the years we have had at least 6 successful pilots of Corvair Powered planes who had personal flying weights in the 300+ club, I can get your Piet weight and balance in range if I know the number. If you are 265#, sorry, it will not even make honorable mention in pantheon of pilots who could have been NFL defensive linemen.

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If you would like to watch a one hour forum I gave on Weight and Balance of Pietenpol’s, including an extensive question and answer session, click on the youtube link above, it will take you directly to my channel. If you have not yet done so, please take a moment to subscribe.

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WW.

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Need Help Contacting the Builder of this Aircraft ASAP.

Builders,

I was forwarded the image of the modified Pietenpol pictured below.  It is Corvair powered, and I have been told it was signed off by the FAA, but I don’t have a record of working with him.

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UPDATE: The builder of the plane has sent a request saying that he wanted the image removed from this story and from our FB ‘Corvair College’ page. He prefers to not discuss his plane in public. I offered to help, meant it. I’m leaving the rest here because first time builders need to understand having a 100 people tell you on FB your plane looks nice isn’t an endorsement of the details.  

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Above is the Plane in Question. I do not consider it airworthy, even though the FAA signed it off.  The first thing Piet builders will spot it the tiny weak diagonal cabanes, as I discuss here: Pietenpol Fuel lines and Cabanes and here: Fuel lines and Cabanes, part 2. But that isn’t the main point, it is the Vee shaped lift struts on a parasol with near vertical cabanes and a center section. It is not structurally sound.

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In 1989, a guy in my EAA chapter, #288, named Bob Spenk, built a steel tube Grega with a nearly identical lift strut arrangement. To my then-uneducated eye, it looked fine. The Embry-Riddle department chair of engineering was also a #288 member, and he sat down and explained that the new strut arrangement had almost no ability  to resist the wing rotating in relation to the fuselage, and any differential load, such as deflected ailerons, would impart this.  He explained that in a cabin airplane with the same lift struts, the upper longerons contacting the rear spar and the diagonals in the fuselage resist the twisting, and he showed us that one of the largest tubes in a J-3 fuselage does this.  He went on to show that a heath model V parasol has no center section, but it still requires diagonal brace wires from the rear spar lift strut attachment to the motor mount.  He pointed out that a it was superseded by the Heath N, and follow on airplanes like the Baby Ace, with parallel lift struts are required to have the diagonal brace wires between the lift struts, even though they have no center section.  Aircraft structures is a very complicated business, and it doesn’t care if all the local hangar fliers say “I will be alright” and it doesn’t care if all the people on the internet say “Its just a low and slow plane’.  neither of those statements will make the plane right. it doesn’t work that way.

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“Hey, William Wynne, you are a jerk, mind your own business, the guy is probably very nice and you are only pissing on his parade. He probably isn’t even a customer of yours. This is why many people think you are an ass.”

 …….In 2016, a lawsuit for $350,000 was tried against me. It came from a person who had a Corvair in their plane, but never bought a single thing from me. If you thought that couldn’t be done, I understand, I didn’t previously believe it was possible either, but yes, it can get to federal court.

  ……..If you work in aviation, or even spend time here, you will have to decide at what level you are Your brothers keeper?  I have long ago decided that I’m fine with many people thinking I’m a jerk for pointing out something like the plane above, but I am unwilling to go to bed at night and try to sleep with a pillow made of justifications and rationalizations.

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If you want to read the story of the exact day I learned this, 25 years ago, look here: Effective Risk Management – 2,903 words

“This was the first time I can clearly say I understood the cost of keeping your mouth shut. This was the first step to me becoming the kind of “Bastard” who publicly points out people doing dangerous things.”

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wewjr.

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Oil Change video

Builders,

Kitti Politi and I shot a new video on oil change information today, and evidently I got the coffee/sleep ratio pretty close, because it looks pretty good, I hit it in one take, and I did it straight off the top of my head with no script.  Kitty, who is relatively new to the team, had not previously seen my idiot-savant capability to transform into the caffeine fueled ‘abominable showman’, a performance honed over thirty years working on Corvairs and giving more than 600 public forums on the topic.  She thought this was pretty cool. As long as the Coffee/air ratio stays right at 12:1, we will have many more videos to come.

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Kitty  emailed it to Ken Pavlou in Connecticut, and Volia! just like magic, Ken makes a professional video appear on my Youtube page an hour later. Use the link below, and look under the “Operations” playlist:

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https://www.youtube.com/channel/UCtg0vELIaWV7NoSEHNzpHwQ

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Above, my favorite Corvair Flight oil pictured in the middle. All of the supplies shown above are discussed in detail in this story: The correct supplies for engine building 

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For a printed story with detail on oil, read this:

Corvair Oil Change interval….. Lessons part #1

and get a look here….

Notes on Corvair flight engine oils.

and here also:

Oil Change interval, meeting the challenge

Below is a broad overview on oil temps in operations:

Thoughts on cold weather operation, minimum oil temps, etc.

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thanks, WW.

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Ken Pavlou 601XL / 3.3 Corvair; Then there was two…

Builders,

At 6pm yesterday we stood in my front yard and listened for a smooth sound from the north; You could hear him before we saw Ken. A low pass and a trip around the pattern, and he was shortly in my front yard. Two fuel stops earlier he left the middle of Connecticut, his Zenith now brought him to north Florida in 7.25 hours aloft.

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Above, my front yard with two Zenith 601XLs, Phil Maxson’s and Ken Pavlou’s.  Combined they have more than 1,000 hours of Corvair powered flight. Phil’s represents a simple solid plane with a very good billet cranked 3.0L Corvair, Ken’s is a high end bird with a Billet cranked 3.3L engine and all the whistles and bells.  I serve both ends of the building spectrum.

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Seriously, if you want to read a really entertaining profile get a look at this: Ken “Adonis” Pavlou advises aviators: “Life is short, Live Large”. It will restore your faith that experimental aviation has some real characters.

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Above, a mischievous band of pranksters: Earl Brown, Phil Maxson, Ken Pavlou, Ron the drummer, and your humble narrator.

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Few visits are complete without a trip to my back yard range. Phil was joking “Maxon Airlines” doesn’t mind if you have firearms in your carry on baggage. Ken Pointed out that “Pavlou Airlines” allows weapons and smoking on his flight.  We were teasing Phil because he had the most expensive 1911 I’ve held in a while, but he pointed out that if you build your own aircraft engine, you can use the savings for some really nice “hardware”.

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Ken is a very illustrious character who has been a fixture in Corvairs and a good friend for more than a decade.  Just one of the really good humans I found in my 30 years in experimental aviation.

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ww.

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Corvair Mission 2019, Part #2 -“Mobile Test Stand”

Builders,

One problem for us to directly serve west coast builders with in person training is the fact my current test stand must be driven to the event in a truck or trailer. In 2016, I did this lap around America: Back in Florida after 7,380 miles on tour., , but it isn’t the kind of tour you can run every year on a budget provided by the overhead from a low cost engine program.  Before this, we had used Pat Panzera’s test stand at College #5, #13 and #18. (all in CA) In 2009 in Washington I used a Zenith 750 airframe for demo runs. These were stop gap solutions, and this year we have an effective solution: The Mobile Test Stand. 

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Above, My test stand, which has run nearly 500 Corvair engines in the last 20 years. It has been through a number of changes, mostly to shrink it in size so it can fit into my enclosed trailer. (The tongue folds and the fuel tank pivots down) with an engine on it, it clears the trailer door by 5/8″.  It works great, but we needed a ‘clean sheet’ design to make it mobile.

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OK, here is the new idea:  Dan Weseman and I have gone over a mobile test stand design which can be unbolted into parts in 20 minutes, and strapped down to a pallet for truck shipping. We already have enough parts to set it up, we need only fine tune the design and build it.  Le’ts say we want to have a training event in Salt Lake City;  All we need is a local builder with a hangar, and we would truck ship the Mobile stand out a week in advance, and fly out commercial. On Sunday afternoon, break it down, put it on the pallet, and head home. We could be back in Florida working on Monday. This concept will make holding many events possible west of the Mississippi.  If we hold a session in Yuma AZ, and one later in Norther CA, the pallet could be driven in a pickup there or sent on a commercial truck. It need not always return direct to Florida. It is easier than anyone on the west coast building a stand, because that can’t easily move interstate nor make one way trips.  When we have big colleges like Barnwell, we can use it to run more engines side by side with out regular stand.

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Now, time to speak about costs: Building this new stand isn’t a big deal, it might cost $1,000 if we go fancy on it, take a weekend, tops.  But let’s start thinking of trips: How about another event in Portland OR? The Mobile Stand will likely cost $400 to move each way. If just me gets on a plane, call the travel expenses $600. Double that if Dan comes also. Maybe $300 more if we need a motel or a rental car.  So a basic trip like this is $1,500 -$2,500, and that is with us volunteering our time.

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I’m picturing doing as many as four or five of these a year. I’m thinking small group events with 10-12 builders. This allows us to do it without the logistics of large colleges like the ones Kevin and Shelley hosted in Texas or the nine done by PF Beck and crew in Barnwell SC. Other than Steve Glover in Chino CA, we don’t have a proven big venue that will draw 50-60 builders in the west for a full scale college, and if you go back and read part #1 of this series, I’m looking for ways to get much more effective training, and I think we are going to do it in smaller groups rather than more larger Colleges. Dan, Rachel and I have seen this work with events like this: Corvair Finishing School #1, Video report.. I still like regular Colleges, but I’m looking at how to deploy our finite resources, particularly time, to get the maximum amount of real information transfer to builders.

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Is this a valuable idea to builders?  Having a Mobile Test Stand solves the issue of taking weeks out of the shop and driving around the country, but it isn’t addressing the cost. Five events at a $2K average is a chunk of money, and I will assure anyone my mark up on parts has a hard time covering that, the $4K of going to Oshkosh and a few free Colleges.  So the core issue here is the simple question: Would you as a builder pay $250 to get into a 10 person training event in your home state? Would you be willing to do this even if your engine wasn’t ready to run? These are questions I would like to hear the answers to and perspectives from builders in the comments section.

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I have held 43 free Corvair Colleges, and there will be more, but to intensify the training in 2019, I’m looking at asking builders if they would be willing to cover the direct costs of smaller training events closer to where they live. I’m also listening for builders (specifically people who have attended at least one College before) who might host these gatherings. Please share your thoughts and possible locations.

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Wewjr.

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“Corvair Fast Burn” Ignition timing settings

Builders:

The sun is just setting here, but 15 minutes ago we had pretty close to standard atmospheric conditions here, and it was an excellent time for an important test I wanted done with a minimal correction factor. I was testing “Corvair Fast Burn” ignition timing settings.

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OK, here is the concept: If you…….

A) Have a tight quench area in the head, as SPA machines them,

B) Have the correct spark plug (the recommended Denso’s, nothing else)

C) Have the carb set for the Correct air/fuel ratio at wide open throttle

The engine can be set to make 98% of it’s potential power output, with greatly reduced ignition advance, giving it a very, very wide margin of safety against detonation.  Even with reduced octane fuels.

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NOTE, this isn’t the air fuel ratio we use. This is just the one captured in the picture. The actual ratio is 12;1 to 12.5:1 . -thanks, ww.

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Above, the digital Air-Fuel meter from this story:Shootout at the Stromberg corral in action. When I say the carb must be spot on for the setting to work, It means you have to have the correct model carb, jetting as we recommend, not something that kind of looks like it.  If you have a carb running lean, it will be very prone to detonation, no matter what other factors are at play.  When you read that 115/145 octane fuel was used on the last of the piston powered airliners and bombers, the dual rating of the fuel is its comparative Octane rating for running lean (the first number) and rich (the second number) The Octane of the fuel you are using means nothing if it is running lean.

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OK, the results. I use the panel of the run stand as a note pad, because it is easier than writing on a clip board in a 125mph wind. The first number is the total timing advance, the second number is the full static rpm of my test prop.

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LooK:

35 degrees (never use this) is 3360 rpm. This worked because it was a cool day, and I have everything set perfectly, on a hot day, sustained power at this setting would be on the ragged limit of detonation.

Now look at 26 Degrees: It turned 3340 rpm. That is 98% of the power output, but with 9 less degrees of ignition advance.  Note this set of tests was conducted with 90 octane gas. I will very shortly have a more formal recommendation to setting the timing on 3.0 and 3.3 Corvairs, but as a starting point, there is no need to use more than 26 degrees. The power output difference is hardly measurable, but the detonation resistance is radically increased.

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Wew.jr.

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