Mail Sack, 11-18-12, Steel tubing, exhausts, advice….


On the subject of Steel tubing and risk management;

601XL Builder and Flyer Ron Lendon writes:

“WW, I really enjoyed this article and was in the drag racing game in the 1970′s as a mechanic. Some of those experiences have prepared me to expect the unexpected and like the Boy Scout motto “Be Prepared”. The learning experiences of building and flying the Corvair powered CH601 have been one of the most enjoyable and exciting endeavors I have undertaken to date. Now that I’m getting older and wiser, I will be paying much more attention to the details of the proven path. Thanks for persisting my friend.”

Pietenpol builder, CC#24 grad, ATP/USMC, Terry Hand writes:

“William, You are correct that safety is not a “one trick pony”. Safety is a combination of choices, not just a single choice of steel tube over wood, for example. Safety is also a recognition of the human factor. The pilot who practices his/her emergency procedures, particularly his or her engine failure procedures, knows and flies the glide ratio of the airplane and keeps their skills up is far better, in my eye, than the pilot who kicks the tire, lights the fire, takes off, and then thinks nothing will happen when they fly 10 hours per year. But, as you have said many times, it is not safety. It is risk management.”

DC-3 owner, International aviator of adventure Tom Graziano writes:

“William, Spot on about the crash worthiness of steel tube fuselages. I’ve been around more than a few crashes. Steel tube holds up/protects the best IMHO. One AT802 crash in particular pretty much had only the cockpit remaining intact – the CSAR guys couldn’t believe the pilot survived, let alone got out and staggered down to a river to wait for rescue. (Pilot did sustain a fairly serious concussion from the ordeal.) My latest project is definitely steel tube. There are some good threads about crash worthiness over on

“I will be changing my fuel tanks from a straight aluminum tank to a polypropylene tank inside an aluminum outer tank/box. Adds a little weight, but its a price I’m willing to pay for the extra margin. Self-sealing bladders are probably the best way to go, but their weight, maintenance, life limit, cost, and availability makes them not so feasible to me. I’ve decided to install self-sealing breakaway fittings at the tanks and one or two other key places. I saw a Super Cub crash once where the fuel lines pulled away from the tanks and drenched the occupants with fuel which self-sealing breakaway fittings would definitely have prevented. Fortunately, there was no post crash fire. I believe homebuilders give too little thought or serious consideration to flammability and fire. Toxic fumes from foam, upholstery and other things can kill just as fast as fire….”

Builder Tom Griesemer Sr. Writes:

“The 1960s were — individuals worth admiring.
This paragraph is so true…-Tom G”

Tom, I can think of no better example of the poisonous effects of celebrity culture and how degrading ‘entertainment mentailty’ is than Bruce Jenner. Once a genuine American Champion in the 1970s, today portrayed as a buffoon for the benefit of ratings and consumerism. I know a number of people who work in the national media. The only bias they share is an obsession to find a flaw in any effort, the gap in a personality, the small error in any advancement. This quest to degrade or critique betrays their very ugly view of human nature, a grotesque view that does not acknowledge, and can not permit, the recognition of a Champion or a Hero. They will never focus on how Jenner trained 8 hours a day for 6 years, living near poverty, to defeat the Soviet state trained athletes in the 1976 decathlon. Yet they gleefully show you his fall where he is brought to the pettiness of dealing with a vapid family without a single redeeming quality. They do not believe that an individual, even through intense effort, should be allowed admiration of  society.-ww

Builder, CC#5 grad. and linguist Dan Branstrom writes:

“Both my parents spoke Swedish first. My dad, because he was born in Sweden, and my mom, because she lived in a farming community composed of Swedish Immigrants.For her, it was easy, because her mother had been a school teacher. My dad learned English after he immigrated to the U. S. at 17. He put himself through an academy (high School), two years of college, then seminary, and left for China at 26 and learned to speak Chinese. I asked him what the hardest language for him to learn, and he answered, “English.”

I wrote all that because I understand how difficult it can be, particularly with all the homonyms we have and our hodgepodge of spelling rules we have because our language comes from so many disparate sources William, you do things with a flair, but you flare a tubing or an airplane.Knowing you, you probably flare an airplane with a flair.To get even more ridiculous, a very dramatic person at the scene of an accident would light a flare with a flair. Thanks for the essay on construction modes. The only thing I’d add would be that a good system of restraint is mandatory. At least a 4 point seat belt should be used.-Dan”

I include this note from Dan to show that he functions as my editor when Grace is out-of-town. The corrections often come in stylish sentences like above. Dan lives in CA and has been part of the Corvair movement for a long time and has a very interesting family history.-ww


On the subject of Zenith Exhausts and Advice, Zenith 750, 3,000 cc Builder and Flyer Doug Stevenson (First person to fly a 750 on Corvair power) writes:

“William, I certainly agree with you….these discussion groups can lead you far astray. Much better to go straight to the “horses mouth.” Regarding this topic, my pipes fit perfectly 1/2″ below my 750 firewall, but I do not have any exhaust gaskets between my exhaust pipes and the pipes coming out of the heads. Should I have used gaskets? My engine seems to run and sound fine without any gaskets, and I cannot detect any signs of leakage. (Doug, I would put gaskets in, it’s a good idea-ww)

On another subject, some time back, I complained to you that my coil splitter was defective and would not allow the engine to run properly. I finally discovered the solution to the problem, but not until spending many hours searching for a solution and having four very experienced mechanics try in vain for several hours to fix the problem. I even sent the new splitter back to the factory for replacement without solving the problem. What was so confusing was that when bypassing the splitter and wiring directly from either coil to the distributor, the engine ran perfectly. I even flew the plane on one coil without the splitter for a short period until I discovered what was wrong. The answer was that the coils were wired with reverse polarity. I had learned many years ago from my hot-rodding days in the 1950′s that it didn’t matter whether the coil was wired from the power source to the + or – side of the coil, the engine ran the same. However, not so with a coil splitter, because the diodes in the splitter won’t allow the current to flow in the opposite direction. I’m bringing this to you now in hopes this information disseminated by you will save some other poor builder the problems I endured. Thanks, Doug Stevenson ps: My engine runs like a dream. I’m really happy with it.”

Doug, Thanks for the note. KR builder/flyer Dan Heath reversed the polarity on his coils before flying last year, and it took a bit of head scratching then also. I have had builders suspect the coil splitter, but I have never seen one fail. You are correct, sharing this type of detail advances the movement. I define success in aircraft building as the comparison between what a guy knows going in and how much he knows when the plane flies. Learning isn’t a common goal in all experimental aviation, but it is in the land of Corvairs.-ww

2,850cc Zenith 750 builder CC#22 grad Blaine Schwartz writes:

“William, I appreciate your comments regarding internet builders. I reread some of these posts and it is very clear the author has never seen the business side of a wrench. People just don’t get it: Carl Sandburg once wrote “experience is the best teacher” and there are no words that are more true that. sometimes the truth just hurts. I would much rather seek out the truth based on proven techniques than risk my life on some phony internet expert. Please keep pursuing the pure unadulterated truth for us who use logic in our aviation decision making.-Blaine”

2,850 cc powered Zenith 750 builder/flyer Jeff Cochran (3rd Corvair powered 750) writes:

“William, Every once in a while the photos do not show up on the post. When I click on the icon, it opens a new window that says I am no longer logged on to AOL, and ask me to log in. Would like to see the exhaust photos because I have the same situation. The pilot side has melted some of the fuse skin. I will use your dowel method to bend it down slightly. Meant to ask you about this, so glad it came up.- Jeff”

Jeff, The issue with some photos is that I have taken them out of emails, Grace has a way of correcting this later, but you have to hit F5 on the computer if I sent it out wrong in the first place, sorry about that, I am a troglodyte. Inspect the skin and make sure it’s only paint damage.-ww

Builder Jackson Ordean writes:

” It is the very ‘attitude’ that you exhibit that some folks apparently don’t like is the main reason I tend to believe every word. Don’t change it. I don’t know what to tell ya’ about these guys ‘A’ and ‘B’, except they’re giving the alphabet a bad name.-unabashed fan and future college attendee.”

Jackson, Both A&B are good guys in general, but that doesn’t mean that their advice nor judgment are good to follow. Its OK to be a Fan of the corvair and/or the movement, but I like friends not fans. At Oshkosh a guy told me that I come across as a “know it all” in my writing. I said I was some thing of a “know most of it” on Corvairs. I asked he if he would prefer getting his building information from some one who knew less about the engine or was unsure about their data? I also pointed out that I always tell people I am a caveman, a Luddite, and I can’t paint, fly complex aircraft, sing, dance, do differential equations, be civil with annoying people, or (as Dan Branstrom points out) spell. I am still mystified on how this could be read as being a “know it all.”-ww

On  crash worthiness, Sprint builder Joe Goldman writes:

“How about stress skin construction over aluminum .040 2024T3 oval bulkheads. The Sprint is the same size as the zenith 601 planes, 27ft wingspan, 19′ fuselage. and according to the designer uses 18′x4′ less AL sheets, then the HD601. If I am lucky stall at 38mph@1150lb with 9:1 glide. Off course I have to finish it to prove it.-Joe”

Joe, Sounds like a Sprint should fly a lot like a Zenith 601/650, which I think has a very good combination of factors. The 601s glide ratio was probably higher than 9:1 and is had a low min. sink rate. The Zenith 601/650 are a fairly good STOL planes, even if they are not perceived as such. Woody Harris just told be about landing his at a 1,400′ strip is a very remote part of CA and using less than 1/2 the runway.-ww 

Steel tube fuselages, “Safe” planes and 250mph accidents


I recently saw parts of a discussion of the merits of different types of fuselage construction from a crash worthiness stand point. These discussions go on in homebuilt circles endlessly, and they are mostly harmless banter. People tend to have seen the results of a single accident, or have some type of favorite construction that they would like to promote as ‘crash worthy,’ mostly to reassure themselves that they have made a good choice.

In professional circles, there is little question that steel tube structures are the most crash worthy of the readily available methods of construction for light aircraft. People are entitled to disagree with this, but they would have a hard time statistically supporting their position. My degree from Embry-Riddle is in Professional Aeronautics, which was the accreditation term that covers the discipline of accident investigation. Even back then my focus was on light aircraft and we have 5 feet of shelf space on the sun porch devoted to books on the subject. If your thinking about a basic book on the subject, start with Thurston’s “Design for Safety.” All of the material and data on the porch supports the use of steel tubing.

One of the best ways to look at an issue is study an extreme example, like Ag planes. Almost every successful Ag plane design has a steel tube structure. These aircraft have a very high survival rate in accidents for a lot of reasons like the pilots being very skilled and the fact they almost all wear helmets, but the basic structure of the planes has a lot to do with it. The actual example I use below is just a little outside aviation, but it does a very good job of illustrating the protective nature of steel tubing in accidents.

There are a lot of other factors that go into aircraft safety. Some are often covered, others that are very important get little consideration. Example: Many people, especially people just learning how to fly, are fixated on STOL aircraft because they believe the quoted low stall speeds make a plane easier to fly and thus ‘safer.’ These same people never think about something I would gladly trade low stall speed for: Glide Ratio. Power off, many popular STOL planes have glide ratios of 4:1. The may have stall speeds of 30 mph power on, but they can not flair to land without power from such a speed. Arrive at the ground power off at this speed, pull the stick back and the plane will fly right into the ground. They commonly need to use 65 or 70 mph as a power off glide to have enough energy to flair and check the rate of decent. timing on this maneuver requires some skill, real training and a fair amount of practice. These planes do not “fly like a Cub.”

 If the engine stops in a STOL plane at 1,000′ AGL, you are going to be on the ground in 60 seconds or less, and you are barely going to get a 1/2 mile of ground distance covered in this glide. When you get to the ground you will round out at speed substantially higher than a Cub flairs at, and you will need to time the flair carefully because the energy will bleed off very quickly when you begin the flair. With practice, the actual ground roll can be very short.  A STOL airplane pilot who always flies power on approaches is probably not going to be able to self teach the above technique in a 60 second window the first time he has a power loss. To benefit from the airplanes capability, this must be practiced.

Contrast this with the 56-year-old 1-26 glider in our front yard. With no power or lift and 1,000′ AGL, it will have more than 9 minutes before it gets to the ground. It’s ground track will be more than 4 1/2 miles long. It has a 24:1 glide ratio clean, and 3:1 with the spoilers open and in a slip. the flair is the definition of forgiving. Our glider has 6,000 landings on it, it has never had the luxury of a single go around, and it has never had a single dent put in it in a landing. That’s 6,000 consecutive forced landings with a great outcome every time.  Yet listening to internet chatter about characteristics of ‘safe’ planes, glide ratio rarely comes up.

Food for thought: Here are some of the risk characteristics I think of in light planes, followed by the ratings from most desirable to least (None of this touches on the single most important factor, a skilled alert pilot.)


Steel tube–Composite—-sheet metal—-wood.


rotationally molded—-bladder—-aluminum—-fiberglass


none (glider)—-tips—-wings—-leading edges——cockpit


Low—— medium—-High




I think of the factors as a matrix. Consider the 1-26: It has a steel tube fuselage, no fuel tank, a low stall speed, a great glide ratio, and a steel tube roll over structure and the ability to discard the canopy in seconds by pulling two pins on the inside. Experience says this aircraft is pretty low risk in a forced landing. Conversely, you wouldn’t choose to be in a wood plane with a fiberglass fuel tank in the cockpit, a high landing speed a 5:1 glide ratio and no turn over structure. Chances are your airplane is in between these extremes, but you still have choices. I like the wing tanks instead of header tanks in Zenith HD and HDS models. If a plane had a fuselage tank, I would make it from aluminum rather than fiberglass. It a plane as an optional long wing, choose that. There are combinations I like and those I don’t. Example: I don’t mind flying planes with fuselage tanks, as long as the plane has a steel tube fuselage and the tank is not fiberglass. There are vetos, like no planes that are wood fuselages and pushers, no planes with stall speed much over 65 mph. There are particular designs I would fly, some I wouldn’t fly if you were willing to pay me a cubic foot of $20 bills, and some I wouldn’t fly with a pistol at my head. These are my opinions, the point is to develop your own.

A single factor isn’t king: Two Pietenpols, one steel tube the other wood, which is ‘safer?’ If the wood one has no header tank, strong cabanes and is in CG, I would fly it before I would fly a steel tube plane with a fiberglass header tank, dinky cabanes and an aft CG.

Dan Weseman has a personal rule I find interesting. He will not fly a plane that can not out climb it’s glide slope. If he takes off and climbs out at full rate, he has to know that the plane can turn around and glide back to the airport. For a plane that climbs at 60 mph and has a 10:1 glide ratio, it needs to climb at better than 528 fpm. Ultralights make the grade even though the have poor glide ratios because their rate and angle are both very good.

Keep factor #1 in mind: Who is flying? I would rather land a fast wooden plane at night with a zip lock bag of 100LL in my lap, a lit Cuban cigar in my teeth and my feet chained to the rudder pedals than take a trip around the pattern on a sunny day in a Stearman with some of the pilots I have met. I am serious. Avoid these people like your life depends on it, because it does. Make it your goal in aviation not to be one of these pilots.

Back to looking at a single factor, the steel tube fuselage.  Here is the best example of their strength: Top fuel dragsters. Their frames are steel tube structures, made very much in the same way as aircraft fuselages. A fuel rail weighs about 2,000 pounds. take everything off but the steel tube chassis, and it weighs about 400 pounds. The tubing is bigger than light planes, but most planes don’t go 325 miles per hour and none have 7,000 hp. Below is a link to a phenomenon of the 1980s called a “Blowover” I was present at the 1986 summer nationals at Englishtown and saw the very first one from the 800′ mark on Garlits’s side. It was stunning in person. He flew by backwards going 225 mph.  Watch the video to know that Garlits is the greatest show man on earth because he drove back down the track to the middle of the grand stands, got out on his own, stood up and took a bow. 75,000 fans went wild, we had just seen the greatest moment ever in Drag racing, the purest of American motor sports.

The link:

(Above) The 1990 photo of Don Prudhomme’s wreckage in Montreal. It is outside the rail, and went over backwards at 250 mph. The lightly built front end is gone, but the drivers section is intact. This was one of two wrecks like this for him in one season. He was protected enough to not only live, but come back a week later and compete.

 There is no wood structure that could be built as a chassis for a fuel rail that would protect a driver in a blow over. Steel tubing works. Notice the drivers get right out of the dragsters even after the most violent of blow overs. Prudhome, Hill and Collins were all doing more than 250 mph. When you watch the details, notice that dragsters don’t have diagonals in the frames. They do this to be flexible in ways that are not desirable in fuselages. People often talk about energy absorbing structures, but they must deform without exposing the occupants. Steel tubing passes this test. Wood often does not.

 Don’t know much about drag racing? Your missing the drama of dueling and the sound of pure thermo-mechanical violence. Ask any person who has felt (it goes way beyond hearing) the launch of two 7,000 hp dragsters and they will tell you nothing compares with it.  If you are a Corvair builder who thinks our favorite engine sounds sweet, you will love it. If a person likes the sound of a Rotax 912, I am sorry, they can’t be helped.

 The two photos below tell an interesting tale. All of the dragsters in the blow overs are rear engine models. These came into being in the 1970s. If you think that the blow overs required people of a particular courage to keep racing, you are correct. But if you asked any of them, they would all gladly testify that the required courage was less than what it took to drive Front engined fuel rails, arguably the most demanding and dangerous motor vehicle.

 These emerged in the 1960s. Advances in engines made thousands of hp available before chassis design caught up, and when safety was drivers in open-faced helmets, sitting on the ring and pinion, with the clutch between their legs, and a raging blown Chrysler in front of their face. These were very special humans with the courage to do this.

The 1960s were a period of time when we generated a number of people willing to take risks to achieve something. To me, Don Garlits and Neil Armstrong had more in common than most people noticed. Advanced education gave Armstrong a different path than a young man from Ocala FL in the 1940s could hope for, but in their own arenas, their personal courage and their willingness to engage calculated risk made them legends. Today our society is obsessed with celebrity culture, people famous for going to rehab, actors with little talent, talk show people with nothing to say, and all day to say it. It is a distorted reality, and I choose to ignore it and focus on a time when we thought more clearly and knew what made individuals worth admiring.

Aviation, particularly Experimental Aviation is one of the very few pure arenas left where you as an individual can personally challenge yourself and develop your skills and hone your craft. Even in experimental aviation, ever more people are looking for a short cut where they don’t have to learn, where they can get done instead of mastering the task. People who think that way have been poisoned by consumer-celebrity society, and their path doesn’t go far. I have been in aviation for a quarter of powered flight and half the history of experimental aviation, and I will absolutely state that the people who get the rewards of learning, building and flying are only the people who are willing to devote themselves to mastering each of these steps. If you are building your own engine to master it, if you are willing to really understand flight, they you will have your place among people of real values and courage.

 Above, Don Garlits in a front engine blown fuel rail at the moment of the drive line detonating under 2,500 hp. He has just lost most of his right foot. It would be easy to understand if he never got back in a dragster again, but Don Garlits was the kind of American that we respected because quitting wasn’t part of his DNA. He came back from this and competed for 20 more seasons. This event is 16 years before the first blow over. I choose to spend as much of my life in Aviation as possible, because aviation still respects commitment, persistence and courage.

Your fellow Corvair builder, Myron Pickard, above left, (with Archie Frangoudis at Corvair College #14). Myron is a member of the Motorsports Hall of Fame, and one of the owners of the New England Dragway. Myron was a nationally known competitor running front engine top fuel rails with blown Chryslers. Running 6.6’s at over 200 mph with a 2,500 hp Hemi sitting right in your lap is not for the timid. This era predated national sponsorships, and Myron, like most of his competitors, wrenched on the car and drove it. Today he’s working toward a more subtle experience, flying behind a Corvair.-ww

Stainless Zenith exhaust notes, poor Internet advice.


(If you are having trouble seeing the pictures in this article, it is because I am a computer troglodyte. I will have the Brains and Looks of the outfit correct this shortly, check back in the afternoon and hit F5 or Refresh. -ww)


Our friend and 601 builder Russell Johnson sent the following photos of a fit issue with a stainless Zenith exhaust we made in our jigs for him.  The issue he was having was that when bolted up, the pipe touched the base of the firewall. He was asking for advice on this. I covered the simple 5 minute solution for him in a private e-mail the same morning he sent the note.  Russell also asked the same question on an Internet discussion group for Corvairs which I can read, but I am banned from posting on. (I lack civility at times.) The response he got is posted below the pictures, and it is a fair warning not to listen to some advice you get on the Internet, even when it come from seemingly credible sources. I have no issue with Russell, I am just highlighting the point that customer service issues on parts we sell are always better answered by us directly than by looking for a quick answer on the Web. Discussion groups serve a purpose, but answering installation questions on products we sell isn’t one of them, especially if I am barred from responding on that group. If you’re new to homebuilding let this serve to open your eyes to the limitations of quick answers from strangers.


Above, a photo of our stainless Zenith exhaust fitted to Russell’s 601.  First let me point out that we have made nearly 250 of these exhaust sets in the 9 years we have been putting Corvairs on Zeniths. You can see on our Web pages the yellow 60-pound jig they are made in, and see that the CNC bent pipes are absolutely unchanged since 2005. Additionally the blue Zenith motor mount jig we have that makes mounts from CNC pre-cut tubing sets has also been in place, unchanged for nearly 300 mounts. We have more than 60 Zenith 601s flying with mounts and exhausts that came from these tools and work together. The logical question is what is different about Russell’s aircraft that it has an issue?

Several small things that the person who responded on the Internet blew right past. First, we didn’t build Russell’s engine mount. It is a very good job, but it is his craftsmanship. Second, he is using the gold washers under the red mount bushings. We generally do not use these; we put the red bushings directly on the mount. Beyond these points there are other factors that come into play. The Zenith firewall is set in the plane at 13 degrees leaned back. It takes a very small variation in the installation to affect the fit of the exhaust because of the length of the pipes. There are also variables on how the mounts are torqued up. There are also variables in the fit and thickness of the exhaust gaskets and the condition of the pipes coming out of the heads. But either way, there is a very simple solution to resolve any of these variables.


Above, a close up of the fit at the head. The pipe isn’t square because the other end is touching the bottom of the firewall and preventing it from laying flat. This view also shows the bottom gold washer we do not use. The graphite exhaust gaskets are Clark’s part number C-479C. There is some variation in them, and if you have a thin one near the firewall, it will make the exhaust pipe close to the bottom of the aircraft. Additionally, these gaskets seat on the flange welded onto the pipe extending from the head. Many heads have this flange corroded or bent, allowing the exhaust pipe to be displaced. If you have one of these in your heads, it needs to be replaced. We have also seen a front stack that was not seated in the head make the exhaust too close to the firewall. Issues with the stacks are easily seen by observant builders, as when they are correct, they are all in a line and the same height. Remember that you cannot change a stack with the head bolted on the engine, because the pipe will not pass the upper head stud to come out. Heads that went to Falcon have already had these things checked out.

Above, sharp eyes will notice that the engine here is just in the mock-up stage, it does not have lower cylinder baffles nor any pushrod tubes. For the sake of fitting the exhaust, I am assuming that Russell bolted the heads down firmly. The mount bolt appears to be torqued down the correct amount, where the top red bushing is the same size as the top gold washer. Many of the points I bring up here make a small difference, but two of them can add up to thinking that the system is wrong. In Russell’s case, I think that the largest variable is the fact that we did not make the mount, but either way, it is easily resolved.

The correct clearance from the bottom of the fuselage is only 1/2.” This may sound tiny, but the Corvair does not move much in flight. The most the engine moves is actually when the starter is cranked on the ground. If it doesn’t touch while cranking, it will not touch in flight. Why so close? The pipe is 1.5″ in diameter and it is going through a small cooling slot. If it hung down 2″ it would not only have more drag, it would also be touching the cowl. The smooth running Corvair does not need the same pipe clearance that is required on a 200hp angle valve 360 Lycoming. If the installed pipes don’t clear, the simple solution is to bolt them up tight to the head, insert a 1-3/8″ wooden clothes hanger dowel from Home Depot six inches in the end, and gently bend the pipe to the required shape. Wont that crack it? Absolutely not. Get a look at the pipe: it starts out life as a straight piece of tubing 20 feet long. It isn’t heated when it is formed, it is bent cold. It is a particular heat-treat of 304 stainless specifically designed to bend at room temp and never crack. This isn’t just some stainless I picked out at a muffler shop. These are formed by the same company, of the same alloy and on the same machines that make every Power Flow exhaust. I have gently bent 10 or 12 of the pipes we have installed on aircraft. Many of these have been flying hundreds of hours without issue. This is the proven and simple way to have the exhaust fit your aircraft exactly without having to make the cowls with a big giant hole to account for all possible variables.

On the Internet advice issue: Below is a response written by a guy on the Web to Russell’s question. Notably, the guy did get an exhaust and a mount from us six years ago. He put it on his aircraft. Is he in a good position to offer fabrication advice? Not really, his career was in architecture, and most importantly, his plane was wrecked on one of the first flights it made. His test pilot made an error, but when you read the reply below, maybe you can get the picture that this man’s decision-making also played a factor in the accident. His choice of welders and test pilots as local “experts” isn’t good.

The Internet solution:

“I had the exact same problem.  I had a stainless steel fabricator friend of mine try to bend it without success.  He finally cut the pipe and mig welded it back to an acceptable configuration.  I think the cut was at the last bend.  It was a real geometric puzzle, but we made it work.”

Really? Does this sound easier that a wooden dowel and a few minutes? Let’s take it step by step: I can bend these pipes with 20 to 30 pounds of pressure on the dowel. Next, only an idiot would MIG weld a 304 exhaust. 304 is only welded with high-end TIG welders after we back purge the whole pipe with argon. We post flow all the welds for 30 seconds and pay a lot of attention to weld sequence and heat build up. Next, mig welds are brittle, the last thing you want in an exhaust. We have carefully studied the Zenith systems over hundreds of hours, and I came to the conclusion that they were better off without any clamps or supports on them. They are a specific length and stiffness that they will not resonate, nor crack, but they do flex a tiny bit just where this guy and his buddy put a brittle MIG butt weld that isn’t purged, so the inside of the pipe is certainly charred. If the pipe broke at that spot in flight in a Zenith, you would have a very good chance of having a fire. If you don’t fly sitting on a parachute, think that one over. We specifically have these tubes bent in one piece so that there is no chance of that type of failure. Here is a guy telling other people to do something very dangerous. … and totally unnecessary.

Hey William, why are you such a jerk about a small detail like this? What happened to live and let live? Can’t we all be friends? Airplane building isn’t tee-ball or junior soccer. Score is kept here by two very impartial referees, Physics and Chemistry, and when one of these guys decides to eject you from the game, you’re likely to get benched for eternity.

Yeah? So what. I’m not going to follow that guy’s advice when I build my Zenith so why make a big deal out of it? What is the cost to me if the guy gives bad advice if I don’t listen? Go back and read my story I wrote 2 months ago called “If only someone had told him.” It was about Guy A’s Zenith getting destroyed by Guy B when Guy A decided against my advice to play flight instructor. Ready for this? The person offering exhaust advice here is “Guy B” from that story. His own Zenith was totaled by an “Expert,” but “Guy B” had it insured and got a big pay off. On round two he was at the controls when Guy A’s 601 was also destroyed. Three more and Guy B is going to be an Ace. How does this affect you? Planning on buying insurance? Would you like to know how much the rates go up when 2 aircraft in a small pool are destroyed?

I have almost 10 years of work in the Corvair/Zenith combination. We did it the right way, and bought a new kit for ourselves from the factory, worked with them, not against them, did all the testing, developed the parts, wrote an Installation Manual, assisted many people, traveled far and wide and made countless house calls that no one ever was asked to pay a dime for. We have stood behind everything we have done, and never considered using an LLC as a legal loophole to run out on builders. In this endeavor we have been assisted by many Zenith builders who made the process easier and offered encouragement when the light at the end of the tunnel was far away. Does this entitle me to some special award or praise? No, it was just a challenge that I willingly took on, and if some Zenith builders choose it, that is compliment enough. However, what I do not deserve, and our builders don’t deserve, is dangerous advice from Internet experts.-ww


Mick Myal, aviation writer and editor, passes.


Word came from Contact! magazine editor Pat Panzera, that Mick Myal, the founder of the publication, noted experimental aviator writer and editor, has passed away. Mick was known to thousands of traditional homebuilders from attending countless airshows, the books he published and the magazine articles he wrote, the but he will always be best remembered for founding Contact! magazine in 1990 and editing its first 70 issues.

Above, Mick in the yellow shirt captured in a humorous photo greeting the president of EAA Chapter #1,000 in 1998.  This is how I think of Mick, out in the sun, meeting people, a smile and a camera. Of all the people I have met in aviation journalism, Mick was one of the very few to be respected by all kinds of builders. His work to document good ideas and the craftsmanship of individuals is timeless. People will be using the information in his publications 25 years from today.

When I was first getting started Mick and his wife Sue went out of their way to make sure we had an impartial venue in which to be heard. He arranged the engine forums at Sun n Fun for many years, and always included us in the roster, even when we were very small potatoes. They also published the first good story on our work and had our engines on display in their booth at airshows. I need to say that this wasn’t special treatment, 20 other small aviation companies could offer a carbon copy of this thanks to Mick. He liked, documented and offered a forum to all kinds of people in the world of experimental aircraft. He had planes and engines that he was personally fond of, but he covered anything that builders were interested in.

If you have gotten into building in the last ten years, it is very hard to appreciate how powerful aviation magazine editors were before the rise of the internet. Most of them assumed that their personal view of what was “good” should be the only thing to make it into the limited space. In the 1990s the then editor of kitplanes didn’t like anything low tech or simple. Even when we flew Corvair powered planes to airshows he refused to photograph them, and instead covered many engines that arrived on trucks as long as they had water pumps, a “PSRU” and EFI. Other editors would not cover a story unless they were essentially bribed with motels, rental cars and in some cases plane tickets. This was an unpleasant reality of our industry.

In complete contrast, Mick Myal impartially covered every story that made sense, he never let his personal preferences filter what got to readers. He pioneered having incredibly detailed user reports, loaded with real performance numbers. He broke the rules by telling people what planes actually cost to build. He had no advertising in his publications, and he was beholden only to subscribers. He was immune to flattery. He never spoke about his personal experience when there was a chance to listen to some one elses. In his later years, Pat often escorted Mick to airshows. When ever Mick stopped by a forum I was giving, I took the time to introduce him as “The most respected journalist in experimental aviation.” The ensuing applause may have made him a little uncomfortable, but I said it anyway, just because it was true.

While Contact! always covered airframe developments also, it is largely thought of as an engine publication. When Mick got started, the hand full of books and stories promoting auto engine were completely useless, and frequently dangerous bull shit. I spell that out in full so that people today understand that the ‘standard’ of the time was that it was OK to write stories that said auto engines that had never flown weighed less and were more reliable than certified ones. The people who made money promoting this never flew the stuff, but readers who thought they did often spent years building things that would never work or work just long enough to kill them. Before the internet, one man, Mick Myal, made a mission out of educating builders about the good, bad and ugly of experimental aviation. If you missed that era, I am here to tell you that those of us that lived and worked our way through it have very special reason to hold the memory of Mick in high regard. If you have a Corvair engine on your plane or in your shop, know that this man played a positive role in making that possible, in an era when it was really needed.

Mick was always sharply dressed and professional. To meet him, you might think he had a big machine, 40 or 50,000 subscribers. In reality is was a small fraction of this, but Mick was always after quality, not quantity. He probably never saw much of a financial return for his years of publishing, but you would do much better in measuring his wealth by the number and quality of his friends. At airshows in the 1990s that were becoming ever more consumer-spectator showcases, Mick’s Contact! magazine booth was always an oasis for technical people. It attracted a cast of real thinking characters like Vance Jauqua and Steve Parkman, at any given moment spilling over with builders all discussing things they tried and making sketches on paper and looking at each others photos. In the middle of it all, Mick would stand there with a slight smile on his face, undoubtedly pleased with what he had accomplished.

Blue skies and tailwinds to you Mick, thanks for many good things.-ww

Corvair College #24, reviewed in pictures, part three.


Here is part three of the college coverage:

Above, Bill Princell’s (in gray shirt) Pietenpol engine on the stand at 2,500rpm for 15 seconds. I am verifying the full timing advance on the engine to be 30 degrees. This is done with a timing light, such as the one in my hand. For some reason, 10-15% of builders absolutely refuse to set their timing with a light, and fly the plane by only setting the timing statically. This is a sure-fire way to internally harm the engine from detonation.  We have long published a very detailed 9 page instruction sheet on how to install a distributor and time it correctly, complete with pictures. It is on our main website, and we send the directions with every single distributor we sell. How can I tell in an instant that the person I am speaking with never read the instructions? We they ask me questions about what the idling timing setting is. Aviation comes with lots of instructions of all kinds. You will have more fun, spend less money and live a lot longer if you read them. (note that there is no baffle box on the engine. this is why I limited this particular un to 15 seconds. we had just removed the box after a long run to inspect the top of the engine.)


Above, photographic proof that Corvair College is a high pressure all business learning enviornment….Irv Russell and Bill Rotenberry get some serious study time in.

Above, Pietenpol guys Terry hand and Dave Aldrich speaking to each other. Dave is holding a 64 x 35 sensenich that we sold him for his Piet. Armchair experts will claim that “every light plane flies better on a 72″ prop.” That statement is the verbal ID card of a guy who understands nothing about aircraft propulsion and just parrots things he has heard. The prop in Dave’s hands is an outstanding performer on a Corvair powered plane in the Piet’s speed category. We flew it about 70 hours on the Wagabond. I would put it against any other wooden prop on a Corvair powered plane in this speed range. It will also make far more thrust than a 72″ wood prop on a 65-75-85 Continental, and would match the output of a very strong running C-90. You can look on our thrust and HP test reports and see that an O-200 tested right on a 150 isn’t a great thrust producer either. Many armchair experts often incorrectly claim the Cessna 150 has a 72″ prop, it doesn’t, it is 69″. If it would have climbed 100 fpm more with a 72″ prop Cessna would have put one on there. At its very core, homebuilding is about learning. Testing and data are the foundation of learning. parroting old wives tales never taught anyone anything.


Above, I speak with Piet builders and flyers Kevin Purtee and Shelley Tumino. Kevin wrote an in-depth article on his building and flying experience for us three weeks ago. A small facet of his experience is the accident he had this last summer. At the college he reassembled and test ran his 2,700cc Dan bearing engine that powered his plane for 340 hours. Before the college I inspected the engine carefully. Other than a broken ring gear and a bent starter from the accident, there as no damage. On general principle, I retired the crank and the cam from flying. The replacement crank was equipped with a gen 2 Dan bearing journal, but retained Kevin’s original Dan bearing housing. Dan inspected the housing before the college, and replaced the bearings. This was not required, but it was inexpensive. Here is a very convincing demonstration of the accuracy of Dan’s bearing parts: Original engine case and bearing housing, new crank and 2nd generation bearing journal: It went right back together and zeroed out exactly when the cover was bolted back on its original dowel pins. There is a common misconception that the bearing housing has to be ‘line-bored’ to be accurately affixed to the case, or that Dan’s arrangement isn’t able to be disassembled after installation. Kevin’s engine showed both of these assumptions to be wrong.

On Saturday night, we awarded the Cherry Grove Trophy to Kevin and Shelley. The trophy goes to the builders and flyers that have made a great contribution to Corvair powered flight. We have only 8 slots on the trophy, and their names are in the 5th location. In three more years we will retire the trophy and send it to The National air and space museum. Their names join Mark Langford, Dan Weseman Joe Horton and PF Beck, as outstanding members of our movement that went out of their way to make Corvair powered flight more accessible to builders that followed them. Their frequent appearances at airshows far from Texas, their constant promotion of ‘learn build and fly’ and the hosting of the highly successful Corvair college #22 made them the right people to be awarded the trophy in 2012.


Although Kevin’s day job is flying attack helicopters, he also immerses himself in experimental aviation.  Every one who has met him understands him to be a very funny and friendly guy. Kevin is justifiably proud of his 31 years as a warrior, but in the setting of homebuilts, he likes to be thought of as another fellow builder. At the College he wore my sock monkey hat and Shelley had a shirt for him with the ‘hello kitty’ logo embroidered on it. Neither of these two touches worked to fully suppress Kevin’s tough guy nature, but the did very effective show that he has a good sense of humor. Man on the right is long time corvair movement builder Chris Pryce, who has just started flight training with the USAF.

Above, gratuitous Scoob E dog photo. Like many dogs, he gets nervous about being left behind when any type of packing is going on. The fact it took two days to load the trucks and trailers was almost too much for him. He was overjoyed when we finally let him sit in the vehicle several hours before we left. It was his 8th college.


Above, Local dogs Spike and Max were fascinated by all the action around the run stand.

Above, Vision builders Michelle Tomolo and Mike Schwab enjoy their smooth running 3,000 cc engine with Dan bearing. Theri Vision is about half done. It is a combination that many people are looking forward to seeing fly.


Above, packing works both coming and going, and Brian Law offered to comfort Scoob E while we packed up at the end of the day on Sunday.

Above, Grace took this very nice photo of P.F.’s Piet at sunset on Sunday.


Mike and Michelle stand by their 3,000 cc Corvair after it came off the run stand. The engine is equipped with all of our gold parts. Although headed for their Vision EX, this exact engine could power a Zenith, a Piet, a KR, or a number of homebuilts. On most installations, the only engine components that vary are the carb and the propeller. Other than these two items, virtually all parts of our standard configuration engine can be used on any Corvair powered airframe. -ww

Corvair College #24, reviewed in photos, part two.


Tonight’s instalment of photos from college#24……

Above, I give a hands on demonstration of setting the valve adjustment on a corvair. I always prefer to do this with the pan off and the engine standing on its nose. We have a stand for this, but it could be done just as easily with a stand made from two 18″ squares of 3/4″ plywood. In this position the crank sits still and the engine rotates around it. This is how certified engines are assembled in repair stations.

Dan Heath’s KR-2 in overhead flight. It is white on top because composite planes need to stay cool in sunlight, but the bottom of the aircraft shows why he calls the plane “the Blackbird.”


Above, Dan gives a hands on demonstration of how his original 5th bearing design is field installed on an existing fully assembled engine as an upgrade. Several engines at the college featured Dan’s 2nd generation bearing which requires working with the crank out of the engine. He is still in full production on both designs because they serve different needs. Dan and I have sourced a different crank shop and nitriding facility here in Jacksonville to use in addition to our traditional work with Moldex in MI. Builders interested in having their crank done and using Dans bearing can streamline the process by having us take care of the crank and opting for a Gen 2 bearing. The crank comes back as a drop in piece and the majority of the alignment work of the bearing installation is done because the Gen 2 part on the crank is already installed and ground concentric with the crankshaft.

Above, Dan Heath, on the right, talks about his KR-2 with other builders. Many people commented that Dan’s engine installation displayed outstanding attention to detail.


Above, Irv Russell, left, gives a thumbs up after a demo flight in Phil Maxson’s 601. Irv is building a 650 but had never flown in either a 601 nor a 650. This was quickly taken care of at the college. Irv got a jump-start on building his own engine by picking up a closed case from us with a gen 2 Dan bearing already installed. We gave it to him at the discounted price because he used his core motors case and crank as a trade in.

Above, Zenith 750 builder Gaston Brawley finished and ran his 3,000 cc engine at the college. It features a Roy bearing and a lot of very nice detail work, including all of our gold parts, which match is paint job. His alternator bracket is in place, but we rarely run a charging system on a break in run.


Above, Corvair college #20 grad Jon Coxwell had the company of his son at #24, and the pleasure of finishing and running his Aircamper engine. Here both father and son give thumbs up.

Above, another photo of air inlet rings. This is Phil Maxson’s 601 cowl. It is one of our older one piece units. Phil’s plane was finished in our old Edgewater hangar in the spring of 2006. His cowl has been in the same configuration since then, and he has never had any type of heat issue. At the College he flew down with a 3,100cc engine built by Mike Robitie for mikes Cleanex project. Phil is good friends with Mike and opted to break the engine in on Phil’s 601. The history of this plane is a good example that we have long known how to install the Corvair on the Zenith airframe, our own 601 first flying almost 9 years ago.  Builders of these airframes have a very proven path to follow.


Above, something of a coincidence: notice the names, Builders Michelle Tomalo and Shelly Tominio, sisters in Corvairhood, they even look a little bit alike.

Above, At the Friday night dinner, Local host P F Beck took the time to thank his outstanding crew. They did a great job and stayed late into the night and to the last builder was gone on Sunday. We wanted for nothing at the event, these guys set the standard for host performance.

Above, Dan stands beside is 3,000 cc Panther Prototype engine. It is the first engine running with his new, made in America, billet crankshaft. Note that it also has our jointly developed rear alternator arrangement. (a little more full output load testing takes place this week) At the College the engine Greg Crouchley built for his Waiex airframe also featured one of Dan’s billet cranks fitted with a gen 2 bearing.  While they are not required, they are the last word in strength an a good value when measured against the extreme cost of buy-it-in-a-box imported engines.-ww

Corvair College #24, reviewed in photos, part one.


Corvair College #24, the third one we held at Barnwell South Carolina, is now in the history books. After most colleges I sit down and write down a lot of thoughts and ideas that came with the college experience, mix them in with many photos and share them with builders. This review will be a little different, I’ll just let the photos tell the story with minimal captions.

We made it home only 18 hours ago. I slept less than 2 hours the night before leaving, and worked from 7:30 am until 1 am each day of the college. We didn’t leave Sunday until an hour after dark. Today we spent unpacking, as we came up in 3 trucks and 2 trailers. Pictures seem appropriate to cover the story now because my memories of the event are more of a montage of small moments rather than a story line with a central theme. In a week or two that will probably emerge out of the images, but for tonight, every picture will have to tell it’s own story.

Above, One of the first planes on hand, Jerry Baak’s 601XL with conventional gear. First time I had seen this plane in person. 2,700 cc with a Dan bearing, and all of our components.

Above, Pietenpols of Don Harper (near) and PF Beck (far). They are sister ships in almost every way, with two exceptions: Don’s is a long fuselage and it had a Ribblett airfoil instead of a traditional Pietenpol airfoil. Shortly, PF will be able to offer factual comparative data on the flight performance of each of the airfoils. On the internet, armchair aerodynamictists have pontificated about this from imaginary data for years. Thanks to PF and Don, we will have information worth reading.

Above, Jerry’s engine compartment. Magnificent workmanship. Our Heavy duty oil system fits exactly as intended with the Weseman baffling kit. Plane uses a MA3-spa carb.


Above, our standard 13″ spinner and 66″ warp drive prop combination. note air inlet rings. Jerry reports that the plane runs cool.

Above, Zenith 650 builder and CC#22 grad Larry Magruder works on his 2,700cc Dan bearing engine. It ran on the stand on the last day of the college.

Above, A look at Don’s engine compartment with swing out side panel. This plane uses a front starter and a basic 4 bearing set up.

Above, Pietenpol builder Terry Hand showed up with a very rare find. This is an original 1933 design steel tube fuselage for a Piet made to the flying and glider manual drawings. It was less than half the weight of a steel tube fuselage built to Grega plans. On the front we test fit the high thrust line Piet mount we made for Bob Dewinter’s Piet. We brought this fuselage back to our hangar to make Terry a custom mount and set of die spring landing gear legs. We will have more on this in the next two months.

Above, Corvair college #12 and #16 host Ed Fisher (left) speaks with Brother Roy. Ed has restarted the Sport Aviation Association, Paul Poberesney’s grass-roots aviation group. He has a membership of nearly 750 hard-core traditional homebuilders signed up for it. It is purely about home building, by homebuilders, for homebuilders.

Above, KR-2 pilot Dan Heath flew in for his second year in a row at Barnwell. The plane was looking sharp with a new paint job. The engine is a 2,700 cc Roy bearing engine that has many of our components including our KR/Corvair cowl. The prop is a 54 x 54 Sensenich, the Carb is an Ellison EFS-3A.

Below, father,son and grandson team of the Reddits working on their engine core, destined to be a 3,000 cc engine powering the family project, a Zenith 750.

Above, Phil Maxson of NJ with his Corvair powered 601 XL that has been flying since 2006.

Above, Brian Dempsy, long time EAA member, noted formula V air racer and former C1a world record speed holder works on his Corvair at the college. Brian’s best known aircraft is the racer “Miss Annapolis”.

Part two tomorrow…….

Pietenpol Products, Motor mounts, Gear and Instalation Components.


Below is a series of photos explaining some of the parts we make for Corvair powered Pietenpols. The photos span more than 15 years. I am not a new arrival to the Pietenpol fan club. I can make a very good case that Bernard Pietenpol is the patron saint of homebuilding, the original man who championed the cause of affordable flying for the working class. I have done a lot of work with Pietenpols over the years from building and flying to the weight and balance project, to making several pilgrimages to Cherry Grove. If experimental aviation is supposed to develop your craftsmanship, practicality and self-reliance, following the life work of Bernard Pietenpol has to be the best compass course ever.

My work is Corvair powered Pietenpols has developed from first hand experience over a long time. There are many people who have flown or built a Piet or even two. They probably like the way theirs was set up, people tend to like the plane they know. Very few builders can say they made as many changes and comparatively tested them, had many different pilots fly the same aircraft and offer independent evaluations. Most people have seen photos of Bernard’s personal aircraft: I have performed weigh and balance work on them, my wife has flown the last original, and we later rebuilt the engine on it. I have gone on to make parts that have flown on dozens of Piets. I have even personally studied the results of Piet accidents to learn design detail information. My only allegiance was to what tested better. I am not suggesting that I am some kind of special expert here, I am just saying that I have invested a lot of time and work, it was a labor of love, and I am confident in the data presented. If builders can use the information, good. If it treads on anyone’s differing perspective, they are free to ignore it.

Above, our master welder and side kick Vern takes Bob “Earlybuilder” Dewinter’s motor mount out of our Piet Jig. Bob is picking this up at CC#24 after we have it powdercoated. This is what I call a high thrust line mount, as the thrust line is 3″ higher that a stock BHP mount. Later photos will show the difference on the plane. This mount has a overalll length from the firewall to the prop flange of 32″. This has plenty of room behind the engine, but most important, it is the beneficiary of all the weight and balance data we collected by measuring 30 different Piets on the same electronic scales. Piets have a chronic aft CG problem caused by heavier pilots, light engines and no planning. This mount is part of a very well-developed plan for Corvair Piet builders to follow.

Above is the same mount bolted on a Corvair with our standard intake an MA3 carb and a rear alternator. All of our components are integrated to work together on this.

The above photo shows how our Gold oil pan or our welded oil pan clear the diagonal brace at the front of the mount. Putting it in this position makes the mount very rigid, and gives plenty of room for an uncluttered carb and air filter. The mount is very well-built and 100% TIG welded out of US made 4130 tubing. Dan Weseman stopped by, checked it out in the jig and pronounced that he would fly a snap roll with it. The mount weighs slightly over 5 pounds. It could have been built to weigh 3.5  pounds, and been fine for the way most people fly, but in my judgement, this is the wrong place to look for a 26 ounce weight savings on a plane.

Above, My Pietenpol at the last hours of Sun n Fun 1996. From L to R, Gus Warren, Steve Upson and yours truly. The photo was taken by Mary Jones, the EAA’s editor. We are all smiles, but in reality we were nursing brutal hangovers from drinking “Muzzeloader” (moonshine) at the ultralight party the night before. Note the test cowl that functions like the air box on the test stand. At this point, the plane still had a stock thrust line and stock short landing gear legs. If you look at the cowl there is a 6″ wide filler stripe of aluminum in it. That is due to the motor mount being extended 6″ in one shot to test different CG locations. It flew much better with the CG forward. There are far too many Piets flying at the aft end of the CG range. It only feels acceptable to a pilot who has not flown one with the CG where Bernard intended it to be.

Above, Grace and I stand with my Pietenpol in 2000, the day before Corvair College#1. This is the same airframe after a large re-work in 1998-99. Get a good look at the height difference in this photo and the one before. This has two factors, first the thrust line is 3″ higher on a new mount and the landing gear is completely re-made from scratch and is 6″ taller. Note that it has die springs. Get a good look at the camber angle of the tires with the plane unloaded. This is by design, it gave the plane excellent ground handling. The plane had a large muffler under the belly.

Above, side view of the plane taken the same day at Spruce Creek Fly-in, our airport from 1991-2003. My Piet had a short fuselage. No one should build a short fuse plane today, there is no reason to, it is a complete myth that they have a better CG situation. Notice the new deck angle on the plane. With more angle of attack the plane could be three point landed at 10 mph slower. Look at the axle location of the gear in relation to the LE of the wing. This gear was set to be slightly ahead of the wing in level flight. The brakes on the plane were 6×6 Cleveland hydraulic drums off a Tripacer. This combination of slow landing speed, forward gear and good brakes meant that the plane could actually make landings in 200 feet.  Maybe you don’t plan on flying like that, but every year at least one builder who blindly built his landing gear 7″ behind the LE in accordance with the 1933 plans, puts his aircraft on its back. Planes in ’33 didn’t have brakes and always landed at “Airfields” where you landed directly into the wind. Cross winds and brakes mean it is best to have the gear on your plane where BHP migrated his to in the 1960s, near the leading edge of the wing.

Above, BHP’s last original, Corvair powered of course. This plane has 800 hours on it today, it lives at Brodhead and belongs to our friend Bill Knight. We did the weight and Ballance on this plane two years ago and overhauled the engine last year. On the outside it looks just like BHP made it, but inside it has a nitrided crank, Arp bolts forged pistons and one of our Black prop hubs and hybrid studs. Look closely and understand that BHP kept the thrust line low because he had the stock automotive blower fan on the engine, which sticks up higher than our electric starter set up. Running no fan is what allows us to move the engine up. BHP’s Corvair Thrust line was very near the location of the Ford’s thrust line. It was a familiar location, but if you look at most classic planes, the thrust line is closer to the top longeron. In a parasol, there are aerodynamic reasons why it is better off higher on the fuselage. There are also practical reasons like having more room under the engine for the carb and airfiler, and not having these items too low and prone to damage in an accident. Note that the last original has the main axles far forward and it has die spring in a tube gear like we made the last week for Bob lester’s Piet.

Above, another look at the 2000 version of my Piet. Long gear leges and a high thrust line contribute to the plane having a ‘jaunty’ look. The empty weight of this plane was 734#. Not bad for a plane with electric start and brakes and a wet center section of 18 gallons.  The rail under the tank is a fuel manifold moulded into the bottom of the center section that would drain all the fuel out of the wing at any angle of climb or decent.  My mistake was plumbing it with hard lines instead of braided steel hoses. It could fly in CG with any pilot from 128 pounds to one that weighed 290. It logged about 350 hours in this configuration. Grace produced the cowl by using 2″ scotch brite pads on a radial arm drill press to ‘machine turn’ the cowl. The curve in the paint was traced from a garbage can lid. I dislike a hard paint line between the fuselage and the cowl, a simple curve does a lot to improve the look. Same idea has been on countless classic planes including the last original.

A look at the front end of the plane: The spinner is an 11″ aluminum. I had problems with it cracking and have never had an issue with a fiberglass one. The prop is a 66″ warp drive. Cowling was hinged on the bottom panel to open up in minutes for full inspection.  Boxy eyebrow cooling ducts were interconnected in the back by a 3″ scat hose. They were intended to be a quick test made of scrap aluminum, but we had enough fun flying I never got around to changing them.

If you are a Pietenpol builder and you need a motor mount, spring gear, and intake or exhaust, just drop us a note, we will be glad to help.-ww


Corvair Powered Merlin Flying Over Newfoundland


Below is a retrospective story of building and flying from Newfoundland’s Jeff Moores. He built and has flown a Merlin GT on Full Lotus floats for many years. A while back he opted to move to Corvair power and built up a very nice 2,700 cc Weseman bearing engine that features a lot of our catalog parts, including Gold Systems and a Universal #2 Exhaust.

By being very careful on airframe weight, Jeff states that the Corvair meets or exceeds his expectations. In a long conversation, Jeff explained to me that the “weight spiral,” where an overweight plane gets bigger on several fronts (big engine leads to more fuel in a heavier tank, etc.), actually hits seaplanes two-fold, because when they get heavy they have to switch up a float size to have the buoyancy, and in turn these floats are bigger, adding more drag and weight, which leads to being down on available power. It was a very interesting and practical lesson from a guy who has been flying on floats in a challenging enviroment for a long time. I suspect that until Claude Adams has his 750 flying in Alaska, Jeff will remain the world’s northern-most Corvair pilot. – ww


William asked me to write something about my interest in and my history of flying; something along the lines of Kevin Purtee’s article. For me it’s been a real trip down memory lane!

I grew up in the 1970s and ’80s in St. John’s, the capital city of Newfoundland and Labrador, Canada.  My first fascination was with engines. My second was airplanes because they have engines!  I was never interested in jets, moon landings, or supersonic flight. My favorite planes were, and still are, bush planes. I remember at a very young age hearing and seeing a de Havilland Beaver on skis in the distance on a cold winter’s day.  The drone of that 450 hp P&W radial echoing in the distance … wow. If you have ever watched “Never Cry Wolf” and have listened to the Beaver takeoff after leaving Tyler on the snow-covered ice you know what I mean (crank up the sound and rattle the speakers). I love Cubs, Taylorcraft, Stinsons, Norseman, and most any low and slow tube and fabric aircraft, especially on floats. Oh yeah – I love Pietenpols as well!!

My father was a heavy equipment mechanic for the City-owned busses. He worked there for 42 years before retiring in 1992. He had many interests; anything mechanical, music, drawing, electronics, fishing, and hunting.  He died last October at the age of 80 after a 3-year illness. When I was a kid, he had a subscription to Popular Science Magazine which always contained an ad for the Bensen Gyrocopter. He ordered the plans, which we both stared at and studied many times over the years, but he could not afford to buy any parts while supporting a family on a $50/week 1970s mechanic’s salary.

When I got my first job pumping gas at age 16, I saved some money and we went halves on a Gyro kit. By the time I was 18, we had also bought a 72hp Mac. engine. I traveled to the Bensen dealer in Manitoba and soloed their 2-place machine. I flew ours for a few years on wheels.


Our Bensen gyro in flight

Later we converted it to plans-built wood/fiberglass floats. On the fourth flight – the first day on floats – I misjudged the landing. The float tips dug in and it flipped over. I was under water and upside down in an instant. I remember thinking “I’m going to drown right here, right now”. Luckily I didn’t panic and managed to free myself from the machine and swim to the surface. The gyro was a mess. Dad said when the blades hit the water they stopped immediately. The mast had absorbed the energy and it snapped off behind my back. I emerged without a scratch.

Retrieving the gyro the day after the crash

That evening I called my buddy Ray Hawco to ask if he could take me flying in his Cessna 172 on floats as soon as possible. I knew if I didn’t “jump back on the horse” I would probably never fly again.

I spent a few years after this flying RC models, which was fun but not the same as flying for real. During this time, I had married and completed training as an automotive technician. I began flying training in a Merlin ultralight in 1994. The chap who owned the flying school let me maintain the aircraft in exchange for flying lessons and later for solo time. A few years later, I completed Aircraft Maintenance training in Gander, Newfoundland.

I couldn’t resist when an automotive instructor position was offered at the local community college. I have been there over 20 years now but I always find myself being tugged between the automotive and aviation trades. I prefer to work on airplanes! 

Replacing pistons and cylinders on a C-172

I scratch built my Merlin with dad’s help between 1995 and ’96. Many of the tedious parts like brackets, ribs and tabs were fashioned by him.

Dad fitting the ribs to the wing spar

I cut and notched all of the tubes for the fuselage and tack welded them. The finish welding was done by the welding shop at the College by 4th year students. The welding shop also built a bending brake for me to bend the aluminum sheet for the wing D cells. We also scratch-built the aluminum wing spars. There were never any plans available for the Merlin. However, I had worked on several over the years and had taken many measurements. I couldn’t afford to buy a kit back then but it looked fairly straight-forward to build. I put all of my spare time into it, including my summer vacation, so it got finished in about 13 months.

The first flights of my Merlin took place in October 1996 with a Rotax 532 2-stroke. It flew just as well as other Merlins I had flown over the previous years.I later upgraded to a Rotax 618 which I put about 900 hours on.

Arriving at our family cottage

The two stroke Rotaxes have to be rebuilt at 350 hours, so I had rebuilt the 618 three times. Each rebuild, which includes a new crank, costs around $2000 for parts. They are rough running at the best of times especially below 3000 RPM. The steel frame fabric Merlin acts like a drum magnifying the noise and vibration. Cruising at 6000 RPM I was always anxiously waiting for the engine to explode.

I have always wanted a 4-stroke engine in my plane. When the 912 was introduced around ’98 and followed by the 912S most of the new Merlin kits that were being built here at the time had this engine installed. I had installed and maintained a number of these for owners and found them to be a great little engine with lots of torque. However they were and still are hugely overpriced and the price of parts is ridiculous. A new 912S was around $20,000 (more now). You could buy a good 0-320 for less. Even the few used ones I found were well overpriced.

I had been aware of the Corvair conversion for many years. However I had only seen it in magazines used in “fast” airplanes such as the KR. We actually had a new one at the College many years ago. It had been donated by the local GM dealer in the 60’s for training and was mounted on a stand. When I replaced the retiring instructor in ’89 I decided to get rid of the old stuff he had accumulated over 30 years. You are not going to believe this, but I threw the complete thing in the dumpster!! This was before I knew it could be used in an airplane.

While surfing YouTube about three years ago listening to various airplane engine startups, I stumbled on Gus’ Corvair 701; a slow draggy airplane somewhat like the Merlin. I literally said to my wife who was in the other room to come and listen to this!!!  I announced “This will be the new engine for our Merlin.”  She has always encouraged and supported me in my aviation interest.

Just after our flight in a Standard biplane at Rhinebeck Aerodrome

I found and ordered the Conversion Manual. I quickly located a core engine locally and began the disassembly.

My core engine

Ordering parts and reassembly followed but got interrupted several times by work and dad’s illness.  I had the heads and cylinders reconditioned locally by a long time friend/machinist. The crank went to Nitron. When the crank issues surfaced, I ordered a Weseman Bearing. I finally ran it on a test stand last summer and installed it in the plane over last winter.

Removing the 618

Merlin with Corvair installed

The do or die moment was in June this year. I had high speed taxied it back and forth the pond (lake) several times on the step. Except for a low ceiling and some drizzle which I had flown in many times before, the conditions were perfect – light wind, no boat or air traffic … there was no excuse. Full power, on the step and liftoff!! Positive climb rate, over the trees at the end of the pond – now I’m committed.  Man this thing is smooth. Around the circuit several times, starting to drizzle more … don’t push it, Jeff. Come around over the highway … don’t forget the carb heat! Throttle back, little touch of power … perfect landing!!!!  Taxi in to the shore with a huge grin. I love this engine.

My cowling was initially intended to be temporary. I built it quickly this spring utilizing a Dan Weseman nosebowl and baffle kit to allow test flying ASAP. This winter I plan to raise the top of the panel to match the top of a new cowling. I will also need to cut my windshield at the bottom to make it shorter. Once finished, it will be painted to match the fuselage.

Current cowling

Why do I enjoy flying so much? I guess I’m addicted. It is unlike any other activity. I continued to fly after a bad crash. Not a day goes by that I do not spend time thinking about it if I’m not able to fly. I would fly every day if we had better weather here. As I write this, the weather is forecast for at least four more days of RDF (rain, drizzle, and fog). It’s been like this for a week. Newfoundland is a large island stuck out in the cold North Atlantic Ocean. We are part of Canada politically but not geographically and our weather is very different from the mainland.  We set records for fog, rain, snow, and wind.  It is very windy here most of the time. When it is sunny, it is windy. When it is cloudy, it is windy. When it rains, the rain is horizontal.  When it is foggy, it is not windy because that would blow the fog away!!

Gusty wind take-off at sunset

I follow the weather closely to get every bit of flying I possibly can. Even a 15 minute flight before dark after work provides me with a fix. I usually don’t go very far; but I don’t have to be in the middle of uninhabited wilderness.  Low and slow over barrens, lakes, rocks, and trees. When the weather is good, it is beautiful here.


December 29, 2010 – we had snow just 2 weeks before this

Sunset flight over our family cottage

Last summer my wife and I bought land on Paddy’s Pond and built a hangar. For the past 15 years, my Merlin was out in the elements from April to November and in storage with other aircraft for the rest of the time.

Tied down in preparation for Hurricane Igor

Now it has a “home” to protect it, make it last longer and extend the flying season into the winter.

Hangar under construction

The beautiful smooth Corvair engine is a pure joy to fly. For me it just keeps getting better.

Basic Corvair College Skills, examples of learning


There are countless techniques and lessons we teach by example and hands on training at the Colleges. Here I would like to focus on four tasks that every builder should know as part of having  complete mastery of his or her engine. These four skills are 1) Installing and timing a distributor, 2) Running and correctly interpreting a differential compression test and 3) Correctly setting the hydraulic valve lifters. 4) pre-oiling the engine.

At the college I will teach these tasks to many groups of builders 5 or 6 people to a group. Part of my learning process it to immediately have builders repeat the process they just observed so I can answer their questions and closely watch how they do to make sure they understand and have possession of the skill. The tasks are not difficult, but the are different. 85% of our builders are from outside the mechanical world. This is an important distinction. My useful definition of working in the mechanical world is simple; Do you pick up hand tools at work nearly every day on the job? The vast majority of homebuilders do not, and I adjust the learning process to accommodate this reality and give many more builders a much better understanding of their power plant.

I am a middle-aged, long-haired opinionated troglodyte from rural Florida. If I had to earn a living at any task that involved appearance, political correctness or tolerance of intolerable people, I would live in poverty. If I was also required to have IT skills at these tasks, I would starve. My hat is off to our builders who can thrive at such tasks, you are better men than I. This said, my record says that on the subject of being able to teach people how to master simple aircraft engines, even people from outside the mechanical world, I am pretty darn good.

There are a number of factors on why I am good at this. I like people, and I like learning myself. I spent 11 years of my life in college, 8 years full-time and 3 in night school. (This is really ironic because I was expelled from high school on the grounds of poor attendance) I know and love the subject at hand well, and I have honed the transfer of information over 20 years. All of us had teachers who gave the same lecture if there was 50 people 5 people or 2 sacks of potatoes for students. I learned from many very good instructors, and the best always tailor the delivery to the student. After many years I am a keen observer of people learning, and I watch small signals like body language to instantly recalibrate the delivery until message sent=message understood. I may not always look like it, but I am paying detailed attention to builders at colleges. A big College may have 75 builders, and in the 3 days we are there, I am going to adjust the process and delivery to tailor it to each of these 75 individuals.

A guy who works with tools every day on the job and is constantly exposed to having to master a physical skill or understand how a mechanical sub system works often picks up something like distributor installation on a simple presentation and observation. People who work at desk jobs or cover non-mechanical subjects for a living gain a lot from directly repeating the task step by step right after observing it. The flexible lay out of the college allows both of these builders to learn at their own pace, at the same time. The primary thing I am watching is that the builder is comprehending and performing the task correctly. Good delivery is important, and the setting is casual, but I don’t just assume that people got it. I ask people to perform the task, and then I will often ask them to show it and explain it themselves to another builder. This is the best confirmation that they have real possession of the skill.

I am writing up notes for the four tasks, something of a checklist for people to have on hand at the college. I will expand on these here after we return. For now, some source notes:

1) Install and time a distributor. This is already documented very well in print and pictures, but I do go over it many times in person. I do not allow a builder with a complete engine to leave the College without being able to demonstrate to me that he can use a timing light, and that he owns one. If he doesn’t have one, we sell him one on the spot. Your flight instructor didn’t let you solo a plane without certain skills like being able to land. I am your engine instructor, and before you go home solo with your engine you are going to understand ignition timing and how to use a timing light. The distributor instructions ar on the products page of our website and they come with every distributor we sell. look at this link

2) Run and correctly interpret a Differential compression test. Just yesterday I got a letter from a builder referencing a compression test saying that he had compressions “between 165 and 180 psi” These are automotive numbers not differential compression numbers.  Aircraft numbers look like 78/80 or 76/80 etc. I can’t say it enough times, but an auto compression test is like a stethoscope, and a differential compression test is like an MRI and a CAT scan. Which do you think are more powerful tools? Every annual on a certified aircraft requires a differential compression test. The tool is about $70. The most important thing I know about a guy who has a running engine but still sends me automotive numbers is that he isn’t learning anything: he is resisting treating the engine as an aircraft engine; he wants to ‘show me’ how he and his local buddies have always done it. This type of resistance to learning new processes usually just means the guy is stubborn. In aviation, this type of attitude isn’t just tiresome, its dangerous. Being willing to learn how to use a differential compression tester sets you apart from people with shade tree mindsets.

3) Set the hydraulic valve lifters. This is descriptively covered in the manual and it is visually covered on engine building DVD#3, But it is best covered in person. Increasingly people work at jobs that require little manual fidelity and feel. Right now I am typing this on a keyboard that will produce the exact same character if I lightly tough the key or I hammer down on it. We drive cars that are dumbed down with things like ABS and handling characteristics to protect the poorest or most impaired of operators. thankfully, flying is still very far away from this. So is building things with your hands, where feel counts. Setting the valves is an easy skill but if someone is coming from the ‘touch doesn’t matter’ world, they have to slow down a little and get the feel of what is going on. There are 12 of them per motor, and you can set each one several times to get the feel of this, it isn’t a task that you do just once per motor, nor a skill that has to be done in a short time window. Once set, they are good for the life of the engine and never need to be readjusted.

4) Pre-oiling the engine. This is a fairly simple process, and we have a very good set up for this on the test stand. At the college I will get someone to make a 3 minute You tube video of the basic elements of this and post a link to it here after the college. It is something important that requires no tools of value but it does start the life of your engine on the best possible footing. We pre oiled the panther engine for more than an hour. During this time, the oil in the engine went through the filter more than 300 times before the engine ever started. The Corvair is one of the very few engines for light aircraft that can have this done. You can’t do it on a Lycoming without a very elaborate set up, and I have never hear of people being able to do it on other engines. “Buy it in a box’ engine people don’t care about details like this because people shopping for an appliance don’t think like this. However, thinking like this is at the core of being a motor head, a term that I am very proud to be called. It is not a title you can buy, it something you know about yourself after you actually learn and posses skills to take care of yourself mechanically and after you have chosen not to be a blind appliance operator, but a skilled aviator.-ww