Spark Plug Issue resolved…..
Friends,
Earlier this week we had a number of posts on the issue of spark plugs, centered on a hard miss under full power experienced by Guy “A.” I had another two calls with him after he changed to AC R44F plugs that were gapped to .035″. He now reports that the issue appears to be resolved, and he could not get the aircraft to act up as it had before.
In this case, it is worth noting that Guy “A” had previously flown his plane with NGK plugs with out issue. Was the issue the gap, the dirty condition or? In my perspective, he likely could have gone back to a new set of NGK’s correctly gapped and the issue would have likely disappeared. But. you have to ask yourself, by what margin?
I advocate the AC plugs because they are the ones designed for the engine, and GM owned both AC and Corvair. This is my beginning point, but the strongest case I can make is that I have never seen an issue in a Corvair flight engine caused by an AC plug. Because of our central location on the flow of information on Corvairs, I have access to many more case histories than any single builder, in addition to our own testing, and a lot of road miles for comparison. I have good evidence that the AC plugs will work perfectly under a wider range of conditions in a Corvair flight engine than any other plug that builders commonly consider.
If you work outside the engine world, it is often easy to forget some concepts that seem simple on paper, but are often forgotten in a frustrating search for an issue in the hangar. Rule#1 is always Go Back to what you know will work. If you have an issue like a hiccup, and part of your set up is different from the norm, then reset your engine to the norm. In this case, the plugs we are speaking of cost a whopping $9.00 for the whole set. If you have an issue with two variables, or what you suspect are two variables, being able to absolutely eliminate one of the for nine bucks is a diagnosis tool that only a foolish mechanic would not utilize. In the aviation world, you can’t let something like brand loyalty to plugs that worked in your motorcycle color your perspective. Your allegiance has to belong to what works. Experimentation is good, but it always has to be done as the expansion of the envelope from a set up that works perfectly. If what you have doesn’t work flawlessly, then fall back to the known until it does. A number of guys resist this, which would be fine if we were shade tree car guys wrenching on hot rods. But this is flying, and it can be for keeps, and most professionals don’t fool around with biases, brand loyalties nor reasons of ego or saving face.
Many experimentals have a lot of outstanding details. But good aircraft are not made of 99% excellent. They are made of 100% airworthy. The plane having the issue is outstanding, you could easily call it 99% excellent. But with a 1% detail like the incorrect plugs gapped wrong or dirty, it is not 100% airworthy. As builders, it is important to get the basics 100% right. I included the Guy “B” story to illustrate that this spark plug story isn’t a Corvair story at all. A nearly identical mistake in reverse on a certified aircraft produced the same result, a plane, that until the detail is corrected, is not airworthy. Both pilots made a simple mistake and missed a basic element. One of the things I would like to point out is that Guys “A” and “B” have more than 10,000 flight hours between them. Would a beginner have made the same mistake? Could have, but I have been training people to build engines a long time, and in my experience, new guys are very detail oriented because they take nothing for granted. If you think about human nature, you can see how guys with a lot of time around different kinds of planes may get complacent about details. If your new to planes and engines, don’t let this story spook you. If you just approach this in the proven format and not add creative touches like other brands of plugs, you will not have this kind of issue. Arm chair commentators will find that last sentence boring or manipulative. For those of us who will fly something other than a key board or an arm-chair, I point out that reliability is supposed to be more boring than unnecessary risk, and yes, I am trying to convince people to at least start with proven set ups.
One of the people I keep counsel with on Corvair experience is Dan Weseman. I was speaking with him about CC#24 plans when this issue came up. He commented to me that he had never had a single issue, even once, with an ACR44F plug, and they have been the only ones he has ever flown in a Corvair. Arguably, no one has flown the Corvair harder than Dan. He pointed out that the AC’s not only work flawlessly, they are also the least expensive plug on the market. He didn’t really see any motivation for working with any other plug.
In an average year, I will get 200 emails asking about things like constant speed props and elaborate injection systems. If you read all of them, it is easy to tell that 95% of these come from people with little experience. If I lined up these 95% and asked them to install a distributor and time it, or to explain to me how you could tell if the engine was on the top of the exhaust stroke of compression by looking at the motion of the rockers,(both things we teach at Colleges,) I am sure these people would be at a loss. Is there anything wrong with their dreaming of injected constant speed planes? Of course not…if the extent of what they came to aviation to do is dream about things. Conversely, if actually achieving things is the goal, dreaming can not take the place of a rock solid foundation of the basics.
None of us were born knowing this stuff. I am glad to teach it to anyone who wishes to learn instead of day dreaming. I can make a very good argument that the builder who creates and masters the operation of a basic aircraft, is a lot safer, and will experience far greater rewards that any builder operating a plane he really doesn’t understand, or is sketchy on the details of a complex aircraft’s function. The guy with the most basic plane has won the game. The guy who consigns himself to daydreaming has not lost the game…..he wasn’t ever playing. Once the basics are mastered, then moving forward can be done with the understanding that you are not posing or posturing as your own mechanic, you actually have earned the confidence in yourself, the real reward for knowing the subject. -ww
Shortblock Sale, Bring your core parts to Oshkosh
Friends,
We are now 10 hours to departure for Oshkosh. I wanted to send this note out as a heads up to anyone driving in to AirVenture.
We are now in the process of setting up registration for Corvair College #24, November 9, 10, and 11th in Barnwell, S.C. It will be the third year we have had the event at this venue. Corvair Colleges #19 and #21 were very productive events hosted by P.F. Beck and crew. This year, I want to get a lot of builders jump started early, as I would like to have a record number of builders and running engines at #24.
One of the ways for builders to get a jump-start is to have us take care of the case assembly in advance. At the College, everyone can take an hour to watch a case assembly to understand the process, but I would like to have a number of builders with pre-assembled cases go right into pistons and cylinders. This also has the effect of staggering the times that builders arrive at the run stand use on Saturday and Sunday.
Above, a 3,000 cc assembled case with a Weseman billet 5th bearing. The main bearings, cam, gears and nitrided crank are already installed, along with the 5th bearing. This is a very strong jump-start on an engine build.
If you are one of the builders interested in this, bring your core case and crank to Oshkosh, and we will get started with your build. Even if you are unsure if CC#24 is possible for you, we can always ship the case to you when it is completed. If you are reading this, but Oshkosh isn’t in your plan, send us an email, and we will get back to you after the show and work out shipping your core parts in. Even if you have already sent your crank through Moldex, I will be glad to assemble the case and deduct the price of the crank and / or any other parts you may have already purchased. We are flexible on this, we just want to get a new group of builders launched. I have about 20 cases and 9 cranks that are fully prepped, including the new stress relieving before nitriding process. If any core case or core crank has a serious issue, we can just replace it from my collection at modest cost without delay. Dan has the bearings in stock at this time, so we will have the initial cases assembled 30 days after returning from the show.
The price has a number of variables, but first, what they will all have in common: Clean case that passes inspection and has the studs tested. The crankshaft will be magnafluxed, threaded, stress relieved, ground nitrided, balanced and polished. The main bearings will new and matched to the crank. The billet 5th bearing will be installed and doweled to the case. The case will be painted your choice of colors.
The basic case is $2,795. This is for a 2,700cc or a 2,850cc engine case with a reground OT-10 cam and a standard cam gear. On the other end of the scale, a 3,000cc case (machined for larger cylinders) with a new OT-10 cam, a failsafe gear, and a new crank gear will run $3,195. We are willing to work with any combination of features that an individual builder would like (i.e., standard case with new cam, etc.), just let us know what your plan is, we will work with you. Getting started just involves deciding that your time for progress has arrived. -ww
B.H. Pietenpol, Patron Saint of Homebuilding
(WARNING: This took so long to write that I started it by drinking a pot of coffee when the sun was still up and finished it with a few beers through the night to 5 a.m. Nothing created under such conditions is ever going to be described as “even-tempered.” Read it when you have some time to consider its basic truth. Rushing through things is the most common way we have of cheating ourselves out of the value of nearly every experience. Watch 10 minutes less TV today, and read this with your full attention.)
If you don’t yet know it, you should understand that Bernard Pietenpol is The Patron Saint of homebuilding. This isn’t because he was the first guy to fly a Corvair. Just the reverse is true; it was almost inevitable that he was going to be the first guy to jump on flying a Corvair, because first and foremost, he was the champion of the common man having access to flying his own plane. He may not have been the first guy who understood that aviation wasn’t a spectator sport, but developing the Aircamper and the Ford Model A conversion in the late 1920s put him on the map as the guy who was doing something about it.
He understood that it was against the grain of Americans who worked for a living to resign themselves to watching the rich and privileged have all the fun of flying. Bernard probably had no issue with Howard Hughes getting to join the mile high club with Jean Harlow, but Bernard didn’t think the rest of us should satisfy ourselves with being anyone’s line boy. He put a lot of effort into seeing that the rest of us could build a plane, convert an engine, and fly, where and when we wanted to. This was a new concept. Go back and read The Great Gatsby for a reminder of how the haves thought the have-nots should behave in the 1920s. Henry Ford gave some passing attention to the concept of the Ford Fliver, but trust me, wealthy people weren’t stumbling over themselves to find a way for the common guy to have a path to flying. All of those guys knew that you weren’t going to stay wealthy or get wealthier on the dreams of common Joes. No, this mission had to be done as an inside job, it could only be done by a guy who understood the economic challenges of being a working man. This man lived about as far as you could get, geographically and mentally from F. Scott Fitzgerald’s America. He lived in Cherry Grove, Minnesota, and his name was B.H. Pietenpol.
Ten or twelve years ago, I pointed out that most people mistakenly think that if you cut the cost of the most basic homebuilt project in half, that twice as many people would be able to get in the game. Although this sounds reasonable, it isn’t actually true, and here’s why: Near the economically challenged end of aviation, the cost versus action curve doesn’t graph as a line at a 45 degree angle. In plain English, there are a lot of people who are just outside the budget window of aircraft building. Make it a little cheaper, and a whole lot of new people can get in. The reality that I showed people is that if you cut the cost in half, you might have ten times as many people building. If you are interested in the future of aviation, lowering the cost is the single most important goal. Developing inexpensive and accessible solutions to homebuilding questions is a lot more difficult than developing expensive products for wealthy people, but it must be done if flight is to remain accessible. I am not willing to throw in the towel on this just because we live in an era where the top 1/2% of the population (the people the light jets and turbo props are for) is getting richer by the month while middle class Americans are on ever tighter budgets. My understanding of being an American will not allow me to accept being consigned to spectator status.
Today, a lot of people complain about things in aviation, and how the EAA has evolved, etc. Most of them are lashing out at something they sense is wrong, but they are not always very articulate about it. There is a lot of discussion about it, but it isn’t focused on any central issue. A lot of people are looking back to the EAA of the 1960s with a certain nostalgia, even if they only know that era through reading old issues of Sport Aviation. Because I have been in the EAA since 1989, I am a working class guy, I have read countless works on the topic, I have made pilgrimages to Cherry Grove, and I have two decades into teaching people how to build affordable aircraft, let me step forward and suggest that I know the central character of all of the issues that rank and file guys have.
Whether they are articulate about it or not, working class guys know that the pendulum has been swinging the wrong way for at least 20 years. It is actually getting harder for common Joes to build and fly their own aircraft. This is exactly what Pietenpol struck his blow against. The momentum of this carried into the 1950s with the establishment of the EAA. The far end of the pendulum’s path may have been in the late 1960s, maybe in the affordable days of composites in the 1970s, or even in the ultralight craze of the early 1980s. But since then it has been moving in the wrong direction, and deep down, working guys know this.
Just because the net flow is in the wrong direction doesn’t mean that there have not been valiant attempts to keep things within reach. There are examples of this. Many people point to the Sport Pilot rule. But it is just as easy for me to point out that our industry is so focused on the desires of the wealthy, that the Sport Pilot rule gets distorted into the Sebring airshow, an event devoted to celebrating the $129K “affordable” plane and the Chinese built Cessna 162. Our entire industry has been focused on serving expensive products to the most wealthy 10% of aviators. Many of the journalists who are allegedly looking out for our future have been mesmerized or bought off with simple flattery, a chance to fly expensive stuff, or an evening at Bean Snappers strip club just north of Oshkosh. In the past six months, many of the old guard of EAA publications have been replaced by an influx of former employees of Flying. I hold little hope that these refugees from the wine and cheese end of aviation are here to reverse the pendulum’s swing. One doesn’t spend 20 years reviewing planes that a modern version of Jay Gatsby would be in the market for and suddenly develop a true love for Aircampers, VP-2s and Flybabies.
Before I go any further, let me come out and say that I have nothing against rich guys in aviation. Hell, that’s why we had Flying and Plane and Pilot. I know a number of wealthy guys in aviation who are very deeply concerned about keeping aviation affordable. At Sun N Fun I had a builder who happens to be very successful offer to fund an expensive piece of R&D under the sole condition that no one know that he made this contribution to the movement. Things like this are something that restores one’s faith in concepts like “the brotherhood of aviation.”
This said, it is plain that our industry has long accepted that the role of working guys is “spectator.” Get this: If we reversed this, and had an industry that championed every entrepeneur who made affordable things, and it got to the point where we were in 1969 where the majority of the planes in Sport Aviation could be built by the majority of the members, I contend that this would have no serious detrimental effect on the choices available to wealthy members. However, from our current situation, we know the reverse is not true.
The working class guys have the same dreams as everyone else, and in some cases they actually have stronger motivation because they understand that there is nothing fair, just or right about them getting sidelined by excessive cost. Follow this closely: aircraft cost money, and no matter how cheap they get, there will always be some people who cannot afford them. But, if our industry is lazy and doesn’t take the challenge to make affordable things, and our journalists are entranced into focusing on the expensive and flashy, there will be less and less entrepeneurs willing to take a good shot at making affordable aircraft. Working class guys make up a majority of people in the EAA. These people did not join a profit driven corporation, nor did they join an entertainment based media company. They joined a membership driven association, and they have a right to expect that organization to serve them. If it isn’t doing it, the first person to hold responsible isn’t the new president. It is all the working class members who paid their dues and complained quietly, but never took the time to write a letter to headquarters, failed to write a “What Our Members are Building” note about their friend’s KR, never voted in for a candidate for the Board of Directors. No one ever got the change they didn’t insist on.
Although they can be blind to it, one of the major enemies of working class guys in aviation are working class guys in aviation. They can be terrible about biting the hands that try to feed them. Here is an easy example; many people ask why I like John Monett. I don’t like him, I respect him. He has a very long track record of trying to make affordable things. He should be championed by many working guys, but more often they talk about him being a charm school drop out. If he is a jerk to you, don’t buy things from him, but don’t let this stop you from appreciating the fact that he has done a lot for working guys who want to build a plane. Burt Rutan was at least as caustic to people in his day, but he abandoned the working class guys 20 years ago, and today he is more likely to be found hanging out on the beach in Bora Bora with Richard Branson and a half-dozen topless girls from Columbia, than he is to be found at Oshkosh. Yet he is hailed as a hero by many working class guys. Monnett has a good reason to be crabby:
Working class guys need to remember who is still In The Arena and who is on the beach.
Second, working class guys need to stop messing with the people trying to serve them. A guy selling plans to a plane isn’t getting rich. People making copies of these plans need to stop, period. People who make obvious copies of things they didn’t develop, should never have any working class guy as a customer. I have seen several people build Aircampers from the reprints of the 1929 plans because these were sold for $20 less than the modern ones from the Pietenpol family. None of these guys liked hearing that the ’29 lift strut attach at the spar was completely unairworthy. I was the EAA 288 Chapter president at Spruce Creek and when I was morally lost I built Lancair IVPs for rich guys. I can flatly say that wealthy guys don’t often make mistakes like this, they are not penny wise and pound foolish, but many working guys are.
Wealthy guys recognize that they need successful people to work for them, to build their planes, so they can go to airshows and tell foolish journalists that they built the plane themselves. They have nothing against their hired gun builder making $12 or even $15 per hour. Conversely, many of us who work to keep aviation affordable know the Brittany Spears Cycle. This is when working class guys love you when you’re an impoverished mousekateer, but the moment you can afford to get large fries at the golden arches, you are now called a sell out on the Internet discussion groups, and it is open season on your reputation. Your only hope is to have a meltdown and shave your head. Once you’re suitably humble, and it’s verified that you are not making a living, working class guys will welcome you back. We are very lucky to have built the Corvair movement before the rise of Internet groups, we are insulated by loyal friends to a great degree, but I can think of many very smart guys with plenty to offer working guys, who have opted out of the market in the past 10 years simply because they got a good look at how others were treated. Maybe they didn’t want to have to shave their heads.
In the end, the main thing any individual can do is run his own show well. This means accepting that you are going to build a plane that suits you no matter what the industry tries to tell you is the right thing for you to buy. This means getting your plans and parts through legitimate sources. This is having a good rapport with the experts that you work with. Having positive comments when others choose pointless ones. All of these things are well within any builder’s sphere of control. Beyond this, you can put some effort into things that are partially under your call. I have gotten very good rewards by being active in our local EAA chapters. I have gotten a lot out of writing articles and stories. I cannot guarantee that there will be any positive effect from petitioning EAA headquarters, but I will say that people who don’t make their opinions known have little room to complain that things haven’t changed.
No matter how it all goes, we will still be here because we believe in what we are doing. I have had my faith in aviation tested a few times, but no matter what has happened, it has always still been there. I can’t say this for most of the things I thought I would always be able to count on 20 years ago. 10 years ago, after a particularly trying week at Oshkosh, Grace had the wisdom to understand that we had to go find something we had misplaced, something that our industry had long forgotten. The drive from Oshkosh to Cherry Grove is about 250 miles, but it takes about 60 years to get there, in the sense that you need to go back in time to get “there.” We spent a few hours in Cherry Grove. Dave Mensink, Grace and myself were the only living people there, but it didn’t feel lonely. We stood on the field where Bernard had 70 years before, laid claim on his right to a piece of the sky. For the next 3 or 4 decades that followed, nearly every guy in homebuilding was a working class guy, and damn proud of it. Along the way, homebuilding got careless and allowed some new people to suggest that the people who invented this were no longer what it was about. If you are a working guy, and you’re struggling to imagine how you are going to build a plane, have no worries. You have a lot in common with the Patron Saint of Homebuilding, and in this arena, that is the only currency that counts. -ww
EAA Corvair Webinar- Wednesday Night, 5/9/12
Friends,
We invite you to visit www.eaa.org/webinar to register for a Hump Day forum on Flying Corvair Planes 7 p.m. Central tomorrow, May 9.
I will narrate a 30-45 minute discussion on Corvair conversions. Charlie Becker of the EAA will moderate 30-45 minutes of live e-mail questions from the audience. We will have a chance to cover some of the new stuff and discuss the upcoming Corvair College #23. The event will be kept for later viewing in the EAA’s archives, but I encourage builders to try to catch it live.
Charlie said already a large number of people signed up for the Webcast. One of the things that I like about a good turnout for events like this and for the forums I give every year at Oshkosh is that it gives the people at headquarters direct evidence that there are still many, many people in the EAA who are interested in craftsmanship, learning and affordable projects. The people at headquarters are pretty smart, and over the years they have adjusted the content and focus of EAA publications to reflect the interests of the membership. Our association has had some large changes in leadership in the past year, and I am sure that the new people will take some time to better understand the many different expectations of the EAA membership. For my small part, I am always looking for positive ways that we can make sure the leadership has a clearer picture of the interests of the traditional homebuilding element of the association. Participating in this Web forum is a good opportunity to accomplish this while getting more information out to builders who have selected the Corvair as the engine that best fits their goals.
If you are on other groups that may have potential Corvair builders on them, we would greatly appreciate you sending out a short message so other builders have a chance to catch this event. We hope to have you there. Thank you-William
3,000cc Case Modifications.
Friends,
Of the three popular Corvair displacement that we promote, the 2700, 2850 and 3,000cc engines, only the last one requires any modification to the Corvairs case. To build a 3,000cc engine, both the heads and the case need to be machined where the new 3,000cc cylinders are bolted on. Again the 2700 and 2850 require no modifications to the heads or case.
Several years ago, Dan, Mark Petz, Roy and myself, got together and came up with an exact set of specifications for the 3,000cc machining, to ensure that any builder could be assured that parts sourced from any of us would be compatible. Previously there had been a number of suppliers for 3,100cc parts, and each of them had their own way of machining, and builders were often stuck with one of a kind engines, or even engines that had to have individually machined cylinders for each hole. When developing the 3,000cc engine the four of us were determined to eliminate this issue.
The single biggest factor aiding the standardization of the 3,000 over the 3,100 is the fact that the design and geometry of the 3,000 is all Corvair, compared to the 3,100 which has the piston pin and compression height of a VW engine. These compromises make the 3,100 require modified rods and custom length pushrods. The 3,000cc engine, by our design, uses stock Corvair rods and standard length pushrods.
There are a number of other advantages to the 3,000 over previous large displacement engines, but I would like to steer back to just the machine work required for this discussion. (A 3,100 engine also required the heads and case to be machined to fit the larger cylinders.) The primary reason why we went to 92mm as the 3,000cc bore over the 3,100s 94mm bore is to improve the head gasket area and decrease the oversize required when machining the case. A 3,000cc engine’s case has the 2mm difference in case bore, this may not sound like a lot, the it is a great improvement if you need to put a helicoil or timesert in the case for a head stud. On the top, the 3,000cc’s head gasket does not break out into the head stud holes as the 3,100 does.
The above photo is from our website in 2008. It shows a highly modified 140hp cylinder head that flew 200+ hours on our 601. The head gasket area extending to the head bolt holes shows it to be a 3,100cc head. (look at the bolt hole all the way on the right side of the photo.) It has flanged VW exhaust, a modification that I no longer think is a good idea on any flight engine. This head has since flown 400 more hours on Dr. Andy Elliott’s high performance 601 XL taildragger. A strong word of CAUTION: No one should consider using stock 140 heads on any flight engine. They are notorious valve seat-droppers, and will actually produce less horsepower on typical 2,700cc engines. Flow-wise, they only make sense on high rpm 3,000’s and 3,100s. The 3,000cc engine we are building for our own aircraft has a set of Falcon heads from a 95hp Corvair. Over the years we have tested countless ideas and concepts. Some, like the heads above have limited application in the hands of the right pilot. The amount of time I spend working directly with builders gives me a very good take on what they are personally looking for in an engine. Our testing allows us to suggest which Corvair will provide what they seek.
If you are heading to College #23, and you are thinking of building a 3,000cc engine, you need to send your case in for machining to Dan very shortly. Several cases have already arrived, and Dan is setting up his very accurate tool room mill to machine these cases. The cost of this modification is $150. Dan wanted me to point out that it isn’t practical for builder to bring their cases to the college and have Dan try to machine them the same weekend. If you are planning on a 3,000cc engine, this is the week to scrub the cases, pack them carefully, and send them to Dan. We will have them ready for assembly at the College. (If your building a 3,000, but can’t make the event, you can still send the cases in for the machine work.) Again, this work is completely compatible with the 3,000cc kits sold by Mark Petz at Falcon and the kits sold by Roy.-ww
MGL vs Corvair ignition issue
Friends,
In the past few weeks we had been going over an ignition issue with 650 builder and pilot Shayne McDaniels. His aircraft refused to run well on the points ignition. He changed the points, went over the system, and even mailed it back to me to have it checked out. Just to be sure, he went over all the other systems on the engine to eliminate the possibility that he was looking at a secondary effect. The plane had been unused on the ground while he was doing some work on it and upgrading things in the panel, and the connection is not immediately apparent that the issue was being directly caused by his MGL disrupting the ignition circuit. Shane is a very experienced builder, and he had received the wiring diagram for the tach hook up from an MGL dealer. This wiring was directly responsable for the erratic ignition. When the connection was removed, the plane instantly ran perfectly. It had been a long goose chase.
Our conversion manual suggests never hooking the tach signal to the ignition. This is for good reason. If you are one of the people choosing to use MGL products, the correct solution is to use a sending unit to count bolts in the flywheel. Dan Weseman as a few sending units for this in his hangar. I am told that MGL even has a sending unit that would perform the same task. Either way, just because a company makes avionics doesn’t mean they understand ignition systems. You might think that they would be very reluctant to suggest a connection that was not tested, but it isn’t the case. I am not singling out MGL. Other companies have also made suggestions for tack signals that proved erroneous. As a builder, the best thing for you to do is choose a system that doesn’t connect to the ignition, (like the Stuart Warner tachs) or only use a system that has been proven over 100s of hours to work with the Corvairs ignition. Grand Rapids, MGL and Dynon are all successfully flying with Corvairs, but none of these are using the tach wiring that the manufacturers first recommended.
The above photo is Shane and Phyllis McDaniels’ 650 at Oshkosh 2011. The fantastic finish work was admired by legions of builders all week. This aircraft was the first amateur built Zenith 650 to be registered with the FAA. When a new model of aircraft comes out and the first one flying is Corvair powered, it speaks a lot about the popularity of the powerplant. This is the aircraft in which the MGL unit was interrupting the ignition.
In our booth at Oshkosh 2011, I stand with three pilots who flew in their Corvair powered Zeniths. From left to right, Shayne McDaniels who flew in a 2,700cc CH 650 from Missouri, Woody Harris in a 2,850cc CH 601B from California, and Andy Elliott in a 3,100cc CH 601B from Arizona. If you add in the time we put on our own 601, you are looking at 1,400 hours of ‘Zenvair’ experience. These aircraft have flown in 40 out of 50 states. We have several dozen other zenith pilots who have written their own chapter in this same story. In the eight years since we pioneered the Corvair/Zenith combination all the development and testing has long been done. Any issue that builders experience today is a case of an aircraft that isn’t of our standard configuration or is having a problem like the MGL tach connection issue.
In the foreground above is Dan Weseman’s Wicked Cleanex. Off his wing, Chris Smith flys the Son Of Cleanex. The photo was taken over a bend in the St. Johns River in North Florida in 2007. Dan’s aircraft used a Grand Rapids system, but Chris’s used an MGL. On the first flight of Chris’s plane, it had a very high oil temp indication, a very serious issue. It made little sense because Chris’s aircraft was a clone of Dan’s, and Dan never had oil temp issues. After investigation the issue was traced to the MGL unit set to read the incorrect value from the VDO sending unit. This type of issue can not happen with a mechanical system. The MGL is a computer person’s idea of a good instrument. It can use many different sensors, but I prefer systems that are fool-proof and use high quality sensors. Chris’s plane did not have the ignition tied to the tach, Chris and Dan made a system to have the tach signal come from a sender counting bolts on the flywheel. To be fair, most people who have studied MGL’s products agree that the things they make today are better thought out than the generation of things in Chris’s aircraft, but builders using them are still advised not to use any connection to the corvairs’s ignition system.
In the above 2007 photo, Gordon Alexander’s 3,100cc Pegzair complete and running had just passed its FAA Airworthiness Inspection. To understand something of Gordon’s sense of humor, its N-number is N129LZ. LZ129 was the Hindenburg. Gordon’s airplane was seven years of hard work in the making. Gordon brought the project down on a trailer from Minnesota to our old hangar in Edgewater, where he commenced a savage 14-hours a day for 100 days to finish it. Inspired by his commitment, Gus, Kevin and I each worked to assist him. Gus guided him through covering the fuselage. I built his motor mount, and Kevin did an enormous amount of work ahead of the firewall. It was the first Corvair powered Pegzair ever. This was probably the first corvair powered plane to have an MGL Enigma panel. I do not critique the company without firsthand experience with their products.
Our 701 testbed in the Zenith booth at Sun ‘N Fun 2010. This aircraft was completed in our shop in 2007. It also has an MGL Enigma panel. In the weeks before the show, Dan Weseman and I worked to upgrade the aircraft with one of his 5th bearings. After Dan installed the bearing, the engine showed a drop in oil pressure. This kind of made sense because of the area of the additional bearing and the fact the engine was equipped with a stock oil pump. Changing to a high volume oil pump required pulling the engine and removing the rear case. After doing so, I was stunned to se the oil pressure was the same. Issue? The MGL sending unit had coincidently failed at the same time as the bearing was installed. I checked the system with a $19 mechanical gauge and found that there was never anything wrong with the oil system. It was $200 in parts and 9 hours of work wasted.
I mentioned this on a discussion group, and immediately found out that MGL has many ‘friends’ on the net. If you read the MGL site, the founder in South Africa has a lot to say which suggests computers and software may be a much larger passion of his than airplanes or flying. This resonates with a lot of high-tech computer people on the net, who are very quick to respond to any comment made about MGL, even if they have never met him, nor flown behind any of his products, or completed a homebuilt. One of my primary issues with MGL was they were selling a fuel flow sending unit that was made out of cheap plastic. The owner of the 701 had installed one, something that made me reluctant to use the plane at all. To any A&P, aeronautical engineer or experienced builder, selling a barbed plastic fitting in a main fuel line is indefensible. Most of the tech Computer people didn’t understand why this was an issue. The division on this is a good illustration of the two different mind sets between the groups.
People whose day job is in the IT world would be hard pressed to think of a person in their field who lost their life on the job. Yet, most mechanics and aviation professionals know several people who were killed in planes. Three of the four mentors in Grace’s flying were Ken Terry, Bob Bean, and Phil Schact. They were all killed in planes in the last 4 years. Phil, along with Bill Hess burned to death in Bills RV-8. Things I don’t know about computers are not likely to physically harm me. There are many things I try to share about practical aircraft construction that are bitter lessons, things people I knew and loved paid dearly for.
Most people know that I am a troglodyte who like mechanical gauges. I fully understand that I am a in a dwindling minority group. Most builders today like elaborate technology. It isn’t for me, but I fully accept that it is something that typical builders want. My only point is if you are in the latter group, you need to understand the issues associated with applying this stuff to your corvair powered plane, and you need to understand that the information you can trust will at times be contrary to the avionics peoples’ recomendations. Because I went to Embry-Riddle and I have worked with experimentals as a day job for more than 20 years, I personally know more avionics engineers than 98% of the people who will read this. If you work outside of aviation, let me teach you something: Most mechanics can fly a plane; Most pilots can change plugs or tires; Most ATC guys can navigate; Most dispatchers can forecast weather; Most linemen can start and taxi a turbo prop; Most glider pilots can hand prop a plane, and so on. As a general rule, people in aviation have an interest that exceeds their job description. While there are obviously plenty of avionics guys who know how to fly, build, navigate, or what ever, most people who work in aviation would gladly tell you that many avionics people think of the rest of the aircraft as a support system for the panel.
While this all may sound like mean poke at avionics guys, there is a very serious point here. If you are new to homebuilding you need to fully understand that avionics guys as a rule have the least appreciation for the bigger picture of things, in our specific case here, why shorting out the ignition on the noisy thing that makes the fan on the front turn might be bad.
One of my pet peeves about this is simple to explain; If we went to Shane McDaniel’s home airport and asked 10 aviators who were around and watched him spend many frustrating hours working on his plane what they thought the problem was, I am sure that 9 out of 10 of them would freely offer “the problem is that he has an old car engine in his plane.” There is little I can do to counter such misconceptions, and realistically, public relations for conversion engines isn’t a goal of mine. I don’t care what other homebuilders think of Corvairs. My only concern is getting reliable information to the builders who have chosen the Corvair as the engine that best fits their personal goals in aviation.
-William
Adjustable Front Starter Bracket
Friends,
Below are photos of our latest evolution on front starters. Since 2002, the only starter arrangement that we have worked with is the front starter. Originally we used hand prop engines, moved to front starters in 1992, Developed and flew the rear starter in 1998-2001, and then came back full circle. In the last 10 years we have refined the front starter several times to make it lower profile (2003), use machined brackets instead of welded ones (2006), switched from welded on ears to bolted on ones (2010), and now we have changed the ear to a single piece bracket with an adjustable slot which eliminates the previous drilled aluminum link. installing a starter now takes a few minutes with three wrenches. No drilling or fitting. If you crank it up and it doesn’t mesh with the sound of prefect engagement, a minute of loosening the bolts and resetting the adjustable bracket will make it correct in no time.
Above, the new bracket bolted on a starter mounted on a 3,000cc Corvair equipped with a Dan Bearing. In the last two years, starters we have sent out have had the front ear bolted on instead of welded on. any of the bolt on ear starters can be retrofitted with the new bracket. The above photo is of the same engine we had on display at Sun n Fun. A number of builders asked about the starter, saying it looked smaller than previous models. It was an illusion; This is the same EA-81 based ND starter we have used for the last 10 years. The main visual difference was that I painted this one black and spent 15 minutes on the band saw removing the shroud around the starter gear. The new bracket has a cleaner look than the previous system, but the concept is the same one that has started 100’s of Corvair builds in the last 10 years. The improvements have been small and evolutionary. I have had much better experiences with things in aviation that are refined and slowly evolved to be what the are rather than things that are new and revolutionary. We can all think of things that are revolutionary success stories like the Vari-eze, but you have to remember that it was the exception. In the 1970s there were dozens of other new revolutiary airframes that didn’t work out, like the BD-5. I like to read about new and exciting things, but I have been much better served by things that are old and proven.
Above is a photo of two dozen of the new brackets. They are CNC machined for accuracy from 1/4″ 6061-T6 plate. At the bottom of the photo are two different spacers. These move the starter forward slightly when installing a Dan bearing. If you look at the top photo, you can see the small spacer between the new bracket and the left hand side gold anodized starter bracket. We have these spacers and pre-machined tail brackets for engines that are assembled with Dan bearings. The tail bracket is visible in the top photo.
-William
Distributor Detail
Friends,
There are a lot of little details on Corvair installations that are best shared in a picture and a few sentences. Below is a distributor clamp, installed as we prefer, on a 3,000cc corvair that we built.
Above, the proper orientation of the three parts of the distributor hold down.
Every now and then I inspect a Corvair engine assembly where the builder has the incorrect clamp, or has it improperly installed. First the nut; the stud thread is 3/8″-24. In its stock form, the nut is a regular fine thread nut. In the car it is unlikely to back off because the little wire clamp effectively spring loads it. In the plane we are not going to count on this. The best nut for the job is an MS21042-6, something you can get from any aircraft catalog. A regular all metal lock nut will often have it locking feature above the top of the stud. The MS nut is low profile and the fact it takes a 7/16″ wrench makes it easier to tighten. (This is the same nut we use on the hybrid studs to hold down the prop hub.)
Under it is the stock GM square washer. It has two little ears that face down to keep the wire from spreading when you tighten the nut. A regular washer will not work here.
Under it is the GM wire style clamp. These are far better than any other type of distributor clamp. When you put the pressure on them the two ends of the clamp make very firm contact with the distributor housing, and then the wire deflects as a little spring. I have never seen one of these move once it is tightened down. The reason why the two parts look shiny is that we have the ones on engines we build nickel-plated for corrosion resistance. A quick shot of spray paint will have the same effect on engines assembled in home shops.
-William
In Search Of … The Economical Carburetor
Friends,
There are a lot of smaller research projects that we work on during a year. One of these that I had kicked around in discussions with Dan Weseman was the potential to use an off the shelf, one barrel automotive down draft carb. Although both Dan and I have made a lot of high-end stuff for Corvair conversions, we are both still interested in keeping the engine and it’s applications affordable. Ma-3 and Elison carbs run about $950 overhauled or new. The are great and serve an important purpose. Stombergs are $250 to $550, and are a very good choice for gravity feed planes. Aiming lower, we are moving into the possibilities of Zenith 268 carbs and motorcycle units. Neither of these offer a significant savings over Strombergs. I am not a huge fan of carbs without float bowls. Aerocarbs, Revfows and Posas have all flown on Corvairs, and they have their fans, but most builders would like a carb that has a float, or a design like the Elison or Rotec that stops flowing fuel when the engine is shut off. I have owned and operated all of the above carbs, and I will gladly say that float carbs are much more accurate at metering fuel.
Below, what we are looking at is a Carter 1 barrel from a 170cid Ford straight six. I bought this carb in a box from Discount auto parts for $149, and paid an additional $10 core charge. This is about as inexpensive as you will ever see for an overhauled carb. The concept here isn’t new. 15 years ago we tested one single barrel Corvair carb and found that it could produce more than 85HP on the right manifold. This Ford carb is significantly better flow potential than the Rochester HV. If you go to our main website and look at the category of flying planes, Dale Jorgensen’s VP2 has been flying for more than 10 years on a single down draft taken from a Chrysler slant six.
Above is a shot of the manifold on the test stand. The test engine is a 3,000cc, 120 hp engine. It makes a good test here because we want to know if the carb is operating near its flow potential. I am guessing that most of the people who may be interested in a Ford carb would be building a 100hp engine, and if the cab demonstrated that it could produce a solid 90 or 95 horses, this would be plenty. This manifold was made from one of our regular cnc bent manifold tubes. The box under the carb is 1.5″ x 3″ tubing. There is a lot of initial reaction to guess that such a flow pattern would be restrictive, but in practice, it matters a whole lot less than most people suspect. We are building a manifold for a 3,200 rpm engine making .65 HP/cid, which is very different from making a manifold for a 160HP sport bike that needs instantaneous throttle response.
Above, the carb mounted. The small red lever is a lawn mower throttle arm rigged to run the choke, in a plane this would be done by a cable. Looking at the carb, think of these thoughts: It can take fuel pressure; the inlet fitting is 1/8″NPT, not a brass nipple for fish tank tubing; It has a choke; It has an accelerator pump; It has robust construction and has a low parts count. The only downside it that it doesn’t have an easy way to control the mixture in flight. If you want to fly at 15,000′, this is an issue. If you want to use this on a Pietenpol, it probably isn’t. In the years we had our Piet, I can’t recall ever having the plane over 6,000′ MSL, and I would guess that it spent 95% of it life below 3,000′ AGL. It had a Stromberg, but the mixture was wired in the full rich position. I would lay a serious bet that 100hp Corvair in a Piet with no mixture control would have a much higher service ceiling than a an A-65 or 75 Piet with the most elaborate mixture control.
