Bruce Culver’s Fokker XXI project concept.


Builder Bruce Culver wrote the note in blue below. He is kicking around a replica of a historic, but somewhat unknown, WWII fighter.  The letter caught my eye because it has some elements  I can comment on from personal experience. I included a three view and a spec. sheet from the original aircraft. These planes fought in one of the least understood facets of WWII, the ‘winter war’ , a 105 day savage conflict between the Finns and the Soviets. In spite of fantastic Soviet numerical superiority, the Finns fought them to a halt in minus 40 degree temps. Their national pride soared, but they learned the bitter lesson that they could count on no allied support beyond gestures. My comments on the project are in green and follow the letter-ww

“This is outstanding, William – thanks for letting us in on the secret that the ancient steam gauges I want to use will be pretty cheap because no one wants them anymore. I wonder what the backup system is for those glass cockpits if you have a major electrical failure – if the fancy panel loses power, you have NO instruments at all. And as you mentioned by implication, nowadays few instructors teach students to fly by the feel of the airplane. I KNEW I should have learned to fly in the ’60s….. Well, there is a lady who teaches around here in a decathlon,,,,,

I want to build a simple LSA replica fighter using the Loehle P-40 as a starting point and ending up with a Fokker D.XXI as the preferred design. I have tried three times to order the information pack from them and still don’t have it, but so much for customer service. Nonetheless I’d like a plane that will be fun to fly, safe and won’t break the bank at Monte Carlo. I also want to build the whole airplane and the engine, so I know what’s in both and can check better for problems, maintenance needs, etc. It will require a complete rework of the kit fuselage, but this gives me a chance to reinforce the cockpit area. One of their customers wrapped their P-40 prototype in a ball getting too slow on landing and stalled it in, but he almost walked away….. The pictures ain’t pretty. So, it’ll be wood, but good wood. The great thing about the Loehle P-40 and the Fokker D.XXI is I can leave most of the kit as it comes in the box and change only the cockpit and forward fuselage areas, so flying characteristics should be the same as the kit design.

My point is, Fokker D.XXIs didn’t have glass cockpits, so I can cheerfully go for the unwanted orphan steam gauges. And a Corvair engine, probably a basic model as it will power an LSA. And remember, there is always a place for knowledgable troglodytes…..”

Fokker D.XXI.svg

General characteristics


Bruce, I like the basic idea and the XXI is a well proportioned aircraft that could be scaled to fit the task. At 28″, the Corvair is narrow enough to fit inside the radial cowl as long as the scale was bigger than 62% (5/8ths). At the Zenith open house dinner this year, Mike Loehle and his wife sat at the table with Myself, Becky Shipman, Dan Glaze and Dave Gardiea. Mike was there to support his covering and painting systems. In recent years, his kit company, just like all others, has felt the pinch of the economy. In years past, Loehle has provided 100s of builders very highly regarded kits, but the company operates in a very scaled back capacity from the peak years. If you sat across the table from him you would understand he still cares about builders, but has trouble justifying a full-time communication staff person. A good friend at out airport has a Loehle P-40 that is about 90% done. Let me say that this aircraft is way to lightly constructed for Corvair power. It is intended for two-stroke rotax engines only. Many more things would have to be beefed up than just the front fuselage.

As an alternative approach, think about the WAR replica aircraft. My next door neighbor built and flew a FW-190 powered by an 0-200. We also had one of these airframes fly on a Corvair in Europe a few years ago. They are 1/2 scale, and are too small except for medium and small pilots, and they don’t have the wing area for LSA. But, the wooden ‘dehavland box’ construction, fared in with non-load bearing foam and glass has merit. A number of one-off 5/8th scale fighters have been made this way. In St Augustine there is a 70% Hawker Hurricane that is probably made from this technique. For wing structure, you may wish to get a look at how KR-2s are made. 10 years ago a group of KR builders tested a new airfoil, and had coordinates for an 18% thick root section. This could be laminated into a very strong box spar. There are a number of low wing wood aircraft that could be studied for ideas like Jodel/Falconair single seaters. You can always look at a steel tube fuselage with wooden formers and fabric, it is possible to make a very shapely plane this way. Even if you don’t yet know welding, a challenging and unique aircraft like you are considering will require learning a number of skills. -ww


Inexpensive Panel……..part one.


In a few late hours I am building a new panel for our Wagabond. I am reverting to as simple as I think reasonably practical. When the aircraft was finished 7 years ago in our old hangar, I let the panel reflect Dave the Bear’s taste in things, as he was the primary guy in the hangar gang working on the plane. Dave had a panel full of vacuum instruments.  Today, with the plane returning to our ownership, I am revising things to a simpler setting.

Everyone is entitled to make things any way they want. There are Corvairs flying in front of $15,000 panels. If it makes the builder happy, and didn’t financially compromise the engine build (like putting a motorcycle carb on your engine to save money for GPS) then I am all for it. Although I am an advocate of simplicity, I am not a zealot for it. Louis Kantor finished his 601XL in our hangar in 2009. It has a full Dynon panel with two large screens and most every option. It was nearly $10,000 in parts. But this aircraft also had a no compromise engine with a Dan bearing, all our Gold parts and an overhauled MA3-SPA. The panel also matched the pilot’s skill set: Louis is an 8,000 hour ATP/CFI. The weather information and instrument capability of the plane wasn’t going to lead him into a situation over his head.

I myself am a Day/VFR look-out-the window kind of pilot. My flight instructor insisted that I be able to fly the plane without any instrumentation. This was common in the age of stick and rudder instruction. On my last biannual he put his jacket over the panel at 2,500 agl above our airstrip, pulled the power off and told me to land the plane. He long ago taught me to estimate airspeed from control pressure and glide attitude. With alert practice it is not difficult to stay within +or- 3 mph without being able to see the airspeed. This comes from being rigorously taught to pay attention to the plane, not the panel.

Ask any instructor worth a damn, and he will tell you that all types of pilots spend too much time looking at the panel, but this is particularly a problem with people trained in glass cockpits. Cirrus aircraft were supposed to be the safety “aircraft of tomorrow”, yet they have a very poor safety record, and many of their accidents have been traced to pilots who were not looking outside. The accident acronym ‘CFIT’ stands for ‘controled flight into terrain.’ If you are bored you can read accident statistics and find out that even though Cirruses all have windshields, owners staring at panels have been known to fly them into the ground. I was in an industry meeting at Oshkosh this year where the head of marketing for Cirrus tried to claim his company had an outstanding safety record. He was openly laughed at. The man’s office is in Beijing, because Cirrus is wholly owned by the Government of the Peoples Republic of China, and the man was obviously paid to say things that were not true.  The FAA and the NTSB investigate accidents and keep records so issues can be identified and improvements can be made. A paid lackey of a totalitarian government isn’t working to improve anything.

My taste in simple panels is not driven by lack of understanding of sophisticated instrumentation. The Lancair IVs we built in the 1990s had an average panel cost of $125,000.Much of that equipment was certified grade stuff that was common to new aircraft like King Airs. It was neat learn about, my friends who were avionics engineers loved it, but shortly it seemed very distant from my personal attraction to flight. To me, the least that does the job is best. If I wanted to fly a long way, I would add something like a Garmin with weather, but this can be done later, no one needs that to get their aircraft flying. Something interesting is that the value of regular instruments has plummeted at flymarts because of home builders shifting to glass cockpits. A lot of the stuff I like is now much less expensive. Be aware that low-cost instruments like “Falcon” have been made in China for the last 15 years and they are junk. You are far better off buying used stuff that still has OEM Cessna stickers on it, or some other marking that ID’s it as a domestic product.

11 holes in the panel;

1) 3.125″ Turn and bank 12 v, found at flymart $25

2) 3.125″  Airspeed indicator 40-140mph, traded my neighbor for $40 set of wrenches

3) 3.125″ Altimiter, taken from 1978 Cessna, flymart $45

4) 3-3/8″” Tach Stewart Warner 82636, new summitracing $116

5) 2 1/16″ Autometer voltmeter  5791, new summit racing $45

6) 2 1/16″ Autometer mechanical oil pressure 5721, $53

7) 2 1/16″Autometer mechanical oil temp 140-280 (fits directly in gold housing) 5741, summit racing, $80

8) 2.1/16″Autometer full sweep Pyrometer (EGT) 5743 with 5429 sender, summit racing, about $175

9) 2.25″ hole for radio (later)

10) 2.25″ MAP gauge, Westach, flymart $25

11) 2.25 ” CHT from radial era aircraft flymart $15, needs 2 ohm sender

 Note: #1, 8,9 and 10 are not required. If you total up the rest of the stuff, it is under $400. With the other stuff, its only $619. I still need a CHT sender, some switches and wire and crimps, so lets call it $750.  Adding the radio later is $600, but that is down the road, and a hand-held could do the same job if I wasn’t bothered by external cords and wires.

I have previously written extensively about how reliable mechanical gauges are, That this tach can not harm the ignition, That having elaborate CHT/EGT to detect problems caused by a cheap carb is not as smart as having less info about an aircraft carb that works perfectly.

I understand that the world loves electronics even if cave men don’t. In 2006 I let two very sharp Embry-Riddle CFI/aerobatic pilots fly about 10 hours in our 601XL. They were very observant and handled the plane with skill. At the end of the second flight, one of them asked me why the oil temp still read even though he had shut the master switch off. I explained that it was because this was a mechanical gauge, and it worked without electricity, it just read pressure in a capillary tube, just the way putting a mercury thermometer in your mouth worked. He looked at me like I was some kind of monster. “Put mercury in your mouth? what are you talking about?” He was 20 years old and this wasn’t in his life experience. He barely understood why some clocks have hands. I explained that I wasn’t a monster, I am a cave man. He ended by saying “Hospitals put mercury in people’s mouths? that’s right up there with Leaches!  Dude, how old are you anyway?”

I understand that I am not likely to convince people who are in love with technology that this is the way to go, I am just trying to point out to new people that there are many people who intentionally aim for the other end of the spectrum for very valid reasons.

Every magazine and every airshow are filled with advertisements for all kinds of electronics, its good business for them, and they are working to get you to buy it even if it doesn’t make sense to you or fit your plan. Electronics are expensive and they have a good markup, and the manufacturers have enough money in  the system to make every Tom, Dick and Harry a dealer who gets 15% for closing the sale, so without realizing it, you have been enveloped in voices advocating the stuff because they get paid to do so. It isn’t because they carefully evaluated your personal needs and made a good decision for you. Thats your job.

Mechanical  gauges don’t have this kind of industry power. There isn’t a single company at any airshow advocating them, they are not buying expensive dinners for magazine editors nor providing golf carts and free rental cars. They don’t have glossy brochures and they have never picked up the tab for a “business conference” at Bean Snappers strip club just north of Oshkosh. The only thing in their sad marketing program is some cave man in Florida likes them…..and oh yeah, that small point….they are totally reliable.-ww

Oscar Zuniga – Guest perspective


Here is a story of building philosophy from our friend Oscar Zuniga. He has been around Corvairs for a long time, and was the local host of Corvair Junior College in San Antonio, Texas, in 2003. Airplanes are part of his DNA, something that will always be part of his life. His newest project is a Corvair powered 601 XL. He is a builder of tremendous energy and enthusiasm. His writing has appeared in many publications, and he has contributed a lot of editing behind the scenes to others. He is an engineer with a decidedly practical approach to building. I have known him many years, but the breadth of his mechanical experience still surprises me. I have a 1959 Triumph 650 project in the hangar. Even looking at it in person, few people recognize it. Oscar saw it in a little photo, and e-mailed me a number of pictures of mint restorations of early British bikes that he and his brother had done “just for something to do.” As you read his story, you will come to appreciate why I am always glad to say we have Oscar Zuniga as a member of the Corvair movement. He is the real thing, a genuine traditional homebuilder.   -ww

To Build

We’ve already got “To Fly” (the Sport Aviation Association’s publication), so let’s talk about “To Build.”  Why do I love to build airplanes?


My parents were born in the 1920s and may not have remembered much of the Great Depression because they were kids growing up through that era.  My grandparents surely remembered it, since they married before World War I and started raising their families during the Depression years.  I learned a lot about life and about frugality and practicality from what my parents and grandparents taught me and from how they lived, but I learned even more about those things from my own growing-up years.  I’m the second eldest of 10 children, and what I learned from growing up among a bunch of other growing-up siblings was that if you didn’t want something, or if you wanted it but didn’t express that desire quickly enough, someone else did and it would be gone in a flash.  I also learned to appreciate anything and everything, from leftover food to hand-me-down clothing, to bent nails that we straightened out by pounding them out with a hammer on the driveway, to cutoff pieces of 2x4s and aluminum TV antennas that the wind blew down and the neighbors tossed in the trash.  I’ve used recycled materials and tools to make and repair innumerable things as I’ve gone through life, and everything that I encounter invariably looks like a lot more things to me than it was ever intended to be.  Putting materials to good use is part of why I build.


My wife and I have two Boston terriers and we walk them every evening after dinner, and have done so for as long as we’ve had dogs (which is 43 years now).  On our walks, I find the usual types of lost and cast-off hardware on the streets and sidewalks … screws, bolts, nuts, washers, and other such bits.  I also find (and pick up) pencils, pens, pieces of rope, tow strap, key rings, pieces of pipe and metal, wood and plywood, and anything else that looks like it might have a useful purpose in my shop or hangar.  And everything does, sooner or later.  I have mended things, created things, reinforced things, assembled things, and replaced things with other things that I’ve found, scrounged, or collected over the years.  Still, I’m not an indiscriminate hoarder or junkyard operator or a pack-rat … I’m a discerning collector of useful things that are in need of “re-purposing” ;o)  Call it my inner “sustainable environment” self.  Finding new uses for things is part of why I build.


My Dad used to say (only half-seriously, because growing up we never lived through truly hard times) that a person should never pass a water-hole, because the next one might be dry.  I’ve always taken that motto to heart, and if I’ve already had a donut with my coffee but everyone else leaves the room and there is still a donut left in the box, I’ll take it.  So it is with airplanes, and so it is with the Zenith 601XL that I have just acquired.  I already have a flying Pietenpol Air Camper, along with a composite Flying Squirrel under construction in my shop, but I simply can’t resist something when it looks like it’s on its way to a worse end than the life I might be able to give it.  And that next water-hole might be dry; I might never get the chance to put life into a 601XL again.  Having the opportunity is part of why I build.




Kevin Purtee’s Corvair-powered “Fat Bottomed Girl” and Oscar’s Continental A75-powered “Scout” at the Old Kingsbury Aerodrome near Seguin, TX.  Upon departure from the event and with 2 people aboard each airplane, despite a 5-minute headstart and a 130 lb. empty weight advantage, Scout was quickly overtaken in climb and then outrun in cruise.


So when does an airplane actually die?  We’ve all read about planes that burn down to a pile of black and gray ash, or planes that are ditched at sea, or planes that roll up into a ball in the woods at the end of a runway.  We’ve also read about planes that were built up from little more than a dataplate and a few leftover metal fittings, a serial number and a set of plans, a set of salvaged wing spars or struts, or even some corroded parts that were used as templates to fabricate replacement parts to bring a “lost” airplane back to life.  Rescued from down in a glacier, or from the bottom of a lake, or from a few rusting bones in the Arctic outback.  When is an airplane truly gone, forever?  Certainly some are lost forever, and I don’t intend to dwell on the morbid aspect by reciting stories of terrible losses, but there are always the marginal ones, the ones that could continue into oblivion or be rescued and we look at them and wonder, “what if-?” and “hmmm…!” and see that there may still be a glimmer of life there.  I’m a sucker for lost causes and for things that have the potential for re-purposing … and when it comes to airplanes, the bar is set pretty low for me.  I can’t bear the thought of an airplane, any airplane, being permanently destroyed.  I’ve heard stories of what goes on at Davis-Monthan AFB in the Arizona desert, where untold thousands of beautiful military aircraft have been chopped up, torn up, scrapped, dismantled, and destroyed – and it breaks my heart.  Less than thirty miles from my former home base in Texas, a contractor for the DoD destroyed 53 Slingsby T-3A “Firefly” trainers that were based at Hondo and were used for initial pilot screening.  Beautiful aircraft, summarily destroyed as a lot due to three accidents that appear to be pilot error, not aircraft inadequacy.  And so it goes; there are thousands of sad stories like this one.  Rescuing things from destruction is part of why I build.


601XL as Oscar first saw it in photos, stored outdoors under tarps in rainy Washington state.


Around Labor Day 2012, my 601XL lay outdoors in Washington under plastic tarps, slowly but inexorably yielding to the cycles of climate and the ticking of time.  It’s aluminum, so it would have taken a lot of cycles of climate and a lot of ticks of time before it would have become just pennies per pound for recycled aluminum to buy someone a case or two of beer.  The ferrous bits that were already fabricated and installed on it gave way much sooner, and they aren’t even worth putting in my scrap bin (well, maybe they’ll find a use for something, but not on an airplane).  The airframe was never even graced with a hand-written serial number or a dataplate and the original builder never applied for a registration number for it with the FAA, so it’s a nondescript and plain Zenith.  Or it was until October 7, 2012, my wife’s 60th birthday, when it came into my possession.  When I first found out about it I looked at the pictures of it and saw an airplane that could live and fly, and have a name, and have a highly-polished shine.  I saw what it could be, not what it was.  It’s in my hangar now, and we’re starting the long and slow process of planning how to get it to live and fly and have a name, and to shine like a polished 601 can look when it’s cared for.  Making a nameless “something” into a personal “something” is part of why I build.


My wife Jay (and her mother “Big Jay” before her) has always had a soft spot in her heart for stray animals.  I can’t recall the number of rain-soaked kittens and scroungy mongrel puppies that have suddenly taken on value when they were spotted by Jay or her mother and were taken in for a meal and given a good home.  The 601 that I’ve taken in will be given a good home.  I’ll give it both an N-number and a name.  It will be cared for, cleaned up, stripped down where needed, and then built back up with my hands and my care and my attention.  I don’t farm out my airplane work (except for welding and machining), and I don’t usually spare much in the way of attention and proper engineering scrutiny.  I figure if I do the job right the first time, I won’t have to re-do it and I won’t regret it later.  And while I’m a scrounger extraordinaire, I also admire the beauty of AN hardware much the same as I do fine guns and crisply-minted coins, and I know the difference between the tensile and yield strengths of aircraft-grade hardware and hardware-store materials.  I know where and how to apply each of them and have seen misapplications of both.  As a mechanical engineer, I think I know a little about how this stuff works, but as a lifelong learner, I always marvel when I get to look at machines that others have built, and I never cease to be amazed by the ingenious ways that materials and methods are applied by clever minds and hands to get a job done.  Learning is part of why I build.


As a builder, I love to sit and think about how to make an assembly come together the way I want it to, but even when I have a pile of scrap metal and cans full of all types and sizes of mixed hardware available to me, there are times when I want to open a package that has come to my doorstep, take out the contents, and then hold a perfectly matched set of six beautiful AN-6 bolts in my hand and know that they are going to connect the propeller of my airplane to the prop hub of my engine.  There is no more perfect solution … Earth, Wind, and Fire harnessed together by those six shiny bolts ;o)  Yes, I’ll put them back in the package until final assembly time and will use whatever is in my parts bin for test-fitting and trial assembly, but the Shiny Bolts will be what I fly with.  Hardware, nice hardware, is part of why I love to build.



Oscar’s Corvair engine cases, 2002.  This is when it starts to get good.  Everything has been cleaned, prepped, inspected, and is ready to start building up into an airplane engine.


The beating heart of my 601 will be a Corvair engine.  I acquired my engine as a project maybe 15 years ago without knowing what I would ever mount it onto.  Now I know.  I didn’t pass up the engine (in pieces, in boxes, partially torn down and partially converted) when the chance came up.  The short block was prepared and assembled at the Corvair Junior College that was held at my home field of San Geronimo Airpark in January of 2003 (story and pictures at .)



Beating heart meets airframe, courtesy of a new ZenVair mount.  Older-style firewall will get the updated reinforcing of later 601s.


I also didn’t pass up the 601 as a bare airframe, a set of plans, and little else.  At age 61, I won’t pass up the chance to see where the airframe and the beating heart end up, because the next water-hole may be dry and, as William says, tomorrow I’ll be one day closer to losing my medical.  Realizing that my time as a pilot and builder are limited is part of why I love to build.



Oscar tries on “Miss Nameless” for size.  Even adding seat cushions and a headset, there is plenty of headroom under the forward-hinged Zenith bubble canopy.  Standard 2700cc Corvair conversion short block sits on a ZenVair powder-coated engine mount.  Picture the lines of the engine cowling… plenty of room for intake manifolds, starter, baffling, and accessories.  A proven combination and a no-brainer.


I guess I build because I have to, because my Creator gave me a creator’s heart, and because there is nothing more satisfying to me than to make something unique and useful out of otherwise ordinary things.  It’s my way of expressing myself, of stretching my mind and hands to new limits, of figuring out how to make something work the way I want it to work in a way that maybe nobody else ever has.  Conversely, sometimes I want to make something work in precisely the same way as someone else has, emulating an elegant solution to something and reflecting someone else’s fine work in my own perfect copy of theirs.  Even copying something that I see and appreciate, I can still use it as a model whose image I can paint on my own canvas, with my own brushes and paints, in my own style.  Sometimes it’s wiser to follow a trailblazer than to keep flailing away at the jungle with my own machete, and the older I get the more I enjoy well-worn trails through the jungle.


I am a patient and meticulous person, so looking at a daunting task like drilling out a thousand rivets to install a spar upgrade on the 601 becomes nothing more than a mental, physical, and spiritual challenge and exercise to me.  Some people cross the Sahara on foot, some swim the English Channel, some circumnavigate the globe alone in a small sailboat.  It’s that same kind of personal challenge for me, and something that I have to do and am driven to do.  I’ll do it one rivet at a time, and then another, and another.  When there are no more rivets to drill out or pull, and no more dulled aluminum to polish, it will be ready to put fuel in and fly.  And in the end, that’s part of why I love to build…. To fly.

Improving communications……a little reading goes a long way.


We have recently had a number of new builders get started, and I am going to take a few moments to share a few basic things that go a long way to improving communications and having builders make best use to the information and parts we offer to build and fly their aircraft.

First: Reality Check: we are a mom and pop company that offers products that are noted for being affordable and proven. We are also known for meeting builders in person at several major airshows, several colleges and numerous house calls each year. All of these things take time and cost money. Nearly every week someone who hasn’t bothered to read our website will do three things at once: He will tell me that I should hire one or two more people for the front office, That I need to give him a price for making him a “180hp Corvair flight engine, turbo normalized of course”, and he will send me an “invitation to join Linkedin, the on-line network of professionals.” This will usually come from a guy who ID’s himself as “Flyboy26” and it will all say “sent from my verizon blackberry.” Experience has shown me that this guy stands a 1% chance of ever building a plane.

Below is an actual series of emails from a guy. I am sure he is a nice person, probably a better human than me, but it illustrates that a lot of our mail comes from people who have not taken the time to understand that our mission is supporting builders who want to learn, build and fly. We do much better with people who understand that we are small and we support a specific goal. We have a long track record of helping people who are willing to learn and get their hands dirty.

“William,I’m thinking of building a LSA Buttercup and want to buy a used Covair 100 hp engine for it. Where can I buy one, how much is the Covair Collage fees and how long is it? What is the fule burn at cruse? “

Does this sound like a person whose goal is Learn-build-fly? Note that the first thing is looking for a deal on a used engine. Reading a half hour on our webpage will find 20 places that explain that the college is free and there are several articles on fuel burn. People fixated on fuel burn and finding deals on things to avoid expense and having to learn are very rarely happy in experimental aviation. Note also the attraction to a challenging aircraft to build, one that will only be completed by a person who is really interested in learning and craftsmanship.

“William, Craigslist produced a guy with a 1964 110 hp Corvair engine with 75,000 mi on it for $350. This is not listed so there must be good reason not to consider it. What do you say? “

My manual specifically list this as a good engine for aircraft conversion. Maybe $59 is a good place to start. I do not like thinking that jumps to conclusions, “so there must be some good reason…” Maybe just reading  the information would be better. 

“What is the price for me to redo an engine including the cost of the collage vs. buying one you have rebuilt to fit a Buttercup? “

Again, 30 minutes on the site has all the information that says the colleges are free and also covers the costs of building engines and what we charge for fully rebuilt ones. Engines we build come with manuals and information, they are the “owner/operators manual” for them. Honestly, I am reluctant so sell anything, especially a complete engine to a person who has a hard time getting basic information from our webpage or from our books.

“I’m looking for a fast and very fuel efficient combination and I like the looks of the Pulsar. With the Rotax 80 hp it delivers 150 mph burning 4.8 gph. Do you think the Corvair 100 hp would deliver 180-190 mph at 5.6 . More importantly will it fit and will the weight and balance work out? Here is a spec page for the Pulsar:, What would the engine,and firewall forward, with starter total cost look like?”

OK, the basics here. Pulsar is out of business, and has effectively been for a long time. Drag doesn’t work like that, it is a squared function, meaning twice as fast is four times the drag. If this persons assumption was true, then all you would have to do is put a 240 hp engine on a pulsar and it would cruise at 450 mph. If he read our webpage, he would find out that we have built stuff for Pulsars, it was only to fit the ‘super’ model, it has flown, it isn’t a great across the board combination, and we were careful who we promoted it to.

At the end of this series I have received 6 automated emails from “Linkedin” telling me that I have to respond to this man’s invitation to join that online ‘network.’ If linkedin works for anyone, I am happy for them, personally my world view is that we need more people who have mastery of a specific skill or have developed craftsmanship. To me business networking is about “who you know” being more valuable that what you know, a mind set I detest. I find it very odd that people who believe in business networking often never put their address nor phone number on any email they send. Maybe a good old returned phone call isn’t new-age enough for them.

I am not picking on this guy in particular, I get 30-40 emails a day just like this. I am only suggesting that a little reading goes a long way, and anything builders can do to get a little background is much appreciated.-ww


Mail sack


On the topic of $59 books vs $1,000 engines and how these often make several cycles through the market; Pietenpol builder/ATP CC#24 grad Terry Hand writes:

“William, Did you at least catch the area code on your caller ID, so when we do see the eBay/Barnstormers listing, we can warn our friends? I had to take my daughter to the “Doc In A Box” on Thanksgiving Day where she was diagnosed with Strep Throat. While I was calling trying to find a clinic that was even open on the Holiday, at least I had the manners to thank them when I called for even answering the phone. Amazing! Semper Fi,-Terry”

Terry, The guy wasn’t really all that bad, he was just typical of people looking for a bargain, not really looking to learn something. If learning building and flying are the goals, reasonable people understand that a better approach would be more productive. – ww

Builder Bruce Culver writes;

“Rinse and repeat………”

On the topic of carb location, Piet builder Harold Bickford writes:

“William, There has been plenty to consider with the last three topics. Gravity feed for a fuel system certainly fits the “simplicate and add lightness” dictum from DeHavilland and others. And we know the system works with the Corvair. A steel tube fuselage is now on the list of changes to the Pietenpol project. I agree we reserve the right to become smarter. Though the whole project will end up representing more time and money than the original estimate (and it was only an estimate) the end product will be a far better aircraft. thanks much,-Harold ”

Harold, don’t take my comments on steel tube fuselages to mean that every aircraft has to have one. I just wanted to get people thinking about these concepts. The wood fuselage on a Piet is fairly stout. The existing plans for Steel tube piet fuselages are not good enough for first time builders to efficiently work from. The Grega plans at massively over built; The flying and glider steel tube plans are for a short fuselage and do not have enough details. I have seen other notes, but they include things like left hand doors. I have spoken with two very skilled aircraft plans draftsmen about the idea of a modern set of drawings, but nothing is in motion.Unless you already know something about welding and are good at planning some details, I would stick with building a Wood Pietenpol-ww

 On the subject of CC#25 California builder Lauren Williams writes:

“William, a bit off subject for this site but on for understanding our machinery…I’m of a mind that everyone should earn their car (or plane for that matter) by building it from parts. If you have to go to school for a year in able to do that, cool. On the other hand if you can’t develop enough mechanical understanding, manual dexterity and respect for machinery to be able to build your own car maybe the whole world would be a safer place if you didn’t drive. Just a wild, alternative reality thought brought on by listening to too much traffic radio. I drove professionally for 15 years and truly believe that a third of the folk out there are exceeding their experience and training levels while another third are borderline psychotic or seriously depressed and just not paying attention. Respect your machinery.-Lauren “

 On the subject of props: International aviator of adventure Tom Graziano writes:

“After studying airfoils for several years (Roncz and Riblett rock!), I turned my attention to props. Anyone wishing to learn about propellers should definitely get a copy of Jack Norris’ book – Propellers, The First And Final Explanation – available at: . They should also check out Jan Carlsson’s website: . I’ve corresponded with Mr. Carlsson and he has loads of propeller knowledge along with an affordable and very much worth having propeller design program. Using a little Jack Norris lingo, Mr. Carlsson “gets it”. One should also take a look at the articles written by the late Paul Lipps, and the Whirlwind clean sheet RV series propeller (Whirlwind “gets it” too!) Just as I learned when studying airfoils, I discovered there is much misinformation, ignorance, old wives tales, and tradition (“don’t confuse us with the facts”), out there when it comes to propellers.-Tom”

Tom, to add to your comments on prop design, I would like to echo your feelings about Norris’s work. What I particularly like about his work is how it is based on using existing respected information with a new way of working with this data. I have read a lot of his work and it is good. I actually think the website is a little ‘over the top’ with a few dozen exclamation points per page and it doesn’t accurately conviegh that Norris work is based on very sound scientific work. I particularly like the stuff he contributed to the CAFE foundation tests. His position argues that optimized props will have the same thrust distribution curve. Note that he isn’t saying they will all have the same blade shape.

Over the years I have read a number of designers argue that they discovered some particular blade shape that made all other designs obsolete. This argument never grabs me. Besides how unlikely it is that a guy working alone would discover something that eluded all the engineers at NACA, Pememunde, The Soviet bureaus and labs in Great Britain, It isn’t logical to think that one blade shape suits all aircraft. One other point: neither the worlds fastest prop driven aircraft (Tu-95) nor the worlds fastest piston engined plane (Rare Bear) have props shaped like the “secret undiscovered design” these people always claim to have “discovered.”

Above, A Soviet Tu-95 ‘Bear.’ This aircraft has held the title of world’s fastest prop driven aircraft for 52 years. Rarely seen in the west, few people appreciate how big it is, it is roughly the size and weight of an early DC-10, about 80% the size of a B-52. It has eight props that are 18 feet in diameter. The aircraft is capable of 575 mph, (about 140mph faster than a P-51D)  With the airframe going mach .82, the rotating prop tips are essentially sonic. (so much for the theory that prop tips above Mach .90 don’t make thrust) Yet still photos show the blades have a conventional planform. This aircraft first flew in 1952 and entered service in 1956. The Russians still built these airframes in the 1980s. If a dramatically better prop design existed on earth, the KGB probably would have found it in 30 or 40 years of looking. If it was patented, I am pretty sure they would not have cared. 60 years into flying, they still have the same blade shape. There are no ‘magic’ prop designs.

Above is a photo of Rare Bear, the worlds fastest piston engine aircraft. It is a modified Grumman F8F with a Wright 3350 cid radial. Several props were tried, but the three blade shown used paddle blades from a P-3 Orion. If highly tapered blades were the secret answer, someone forgot to tell these people. This plane has made a two way pass at 528 mph.

If you are working on completing your first homebuilt, it is my strongest advice that you work with a proven, ‘off the shelf’, existing prop that has flown on your airframe/engine combination before. Props are interesting, and good information about them is educational. But keep the goal of getting your plane  done and flying focused. There are no props that would offer substantially better performance on a Corvair powered aircraft than the proven models in popular use. Conversely, investing in a radical or new design, or letting someone talk you into an unproved design can have a very detrimental effect on your project. Building and operating an experimental aircraft is a long series of good judgement calls based on proven information. Choosing a known prop for your first homebuilt is one of these calls.-ww


My favorite Tach; Stewart Warner 82636.


Below is a picture of my favorite tach for the Corvair, the Stewart Warner 82636.  I have used this tach for almost 15 years. We had one in our Pietenpol and also had one in our Zenith 601XL. I just bought another for our Wagabond.  It has a number of features that make it attractive to Corvair builders. It isn’t cheap at $120, but I do find it to be a good value.

Stewart Warner - 82636 - Deluxe Tachometer

The most important consideration for any tach in an aircraft is that it does not interfere with the ignition system. This tach does not have that issue because it was designed to work with diesel engines which don’t have ignition systems. It works by counting the teeth on the flywheel with a small sensor. This is a very clever tach, and it can accurately read any amount of teeth from 60 to 255. The ring gear we use has 135 teeth. The tach has 8 tiny switches that set it for a specific amount of teeth. It comes with very good instructions that explain this. It takes only 2 or 3 minutes to set. Because it was intended for industrial diesels, the full sweep is 3,500 rpm, a useful range for many flight engines. The Tach is available from a number of places on line, I just bought ours from

Note: Under no circumstances should builders hook up tachometers to the ignition system directly.  If you do this with a traditional gas engine/ignition tach, you are in danger of potentially grounding out the ignition if the tach shorts. I have seen people set these up with 1/2 amp quick blow fuses in the signal line, but I think it is banking a lot on a little fuse.  MGL, a glass cockpit company has given builders false information saying that their glass panels can be directly hooked to the Corvair without issue. Don’t believe this, they sell panels, they are based in South Africa, they wouldn’t know a Corvair if it bit them on the tail feathers. If you are thinking of using a glass panel let us know and we will put you in touch with a builder who has one successfully flying.

Since we started promoting the use of this tach it has become the choise of a lot of pilots. At least 25 of the fleet of Corvair powered planes use one. occasionally one of these builders will report having an issue with getting their tach to correctly read the teeth. contrary to what you might first expect, the issue often turns out to be having the sender too close to the teeth, not too far away. .060″ generally works, but if it doesn’t, move toward .125″ instead of going closer. Once set, my experience is that this unit works flawlessly.

The Corvair has flown with every kind of tach you can imagine. Bernard Pietenpol showed people how to adapt mechanical aircraft tachs; We have used a number of different diesel tachs; and virtually every popular glass panel from Dynon to Grand Rapids to MGL. (These later units have required the signal to be buffered to prevent the unit from messing up the ignition and giving a poor signal). If you want to use one of the Glass panels, good, builders have figured out how to make each of them work. For troglodytes that still like gauges with needles, the 82636 is still my first choice.

In the next week or so, I will put up a few updates on the new Wagabond panel, a dirt simple Day/VFR basic stick and rudder arrangement with a minimum of simple engine gauges. It has about $700 in parts in it. Builder interested in a very simple traditional panel can use it as a model for their own.-ww


Save $59, loose $1,000, repeat for fun….


Yesterday was a very quiet and peaceful day around our airport. People here are very friendly and gregarious, but on Thanksgiving, they tend to focus on family and home, and yesterday there was no one out and around. Grace and the dog drove over to her parents for a few days, but I elected to stay here and enjoy the quiet while getting some things done on our own aircraft, It was perfect blue skies and slightly cool. At sunset I went out flying, climbed to a few thousand feet and just puttered around at 1,800 rpm and just watched the sun sink. When it was gone and the runway lights came on, I pulled the power off completely and glided all the way back in comparative silence. I landed and rolled directly to our front yard.

About 10 pm I realized that I had not spoken to a single person face to face all day long. The only people I had spoken with were on the phone. I had covered about a dozen calls during the day. In the morning parents and siblings, a number of friends in the afternoon, people we know from Corvairs, but the conversations weren’t on technical things.

Mixed in this came a call from a guy who refused to give me his name beyond “Jerry.” He was a bit rude saying that he wanted information about a Corvair flight engine he had bought, but it wasn’t anything I had built. He started off with a sarcastic tone about “wow a real person on the phone.” When I am answering the shop line on Thanksgiving day my tolerance for having him complain that I didn’t return two of his previous calls is low. (If you call and will not leave your name and you need help with an engine I didn’t make, you are not a priority call to return) His story goes like this: He didn’t buy a manual from me because they are $59. Instead he bought an engine for more than $1,000. He tells me that it has the drive end of it opposite the way we do it, that his engine has a gear box on it,but he has no idea if the gearbox is spur or planetary, but he is absolutely sure it is made of aluminum. He wants to build an airframe for this engine he bought.

In a few questions I can tell he hasn’t read much about Corvairs. The thing that is annoying to me is that this doesn’t stop him from saying thing with a tone of being knowledgeable. Without seeing a single picture, I tell him he is wrong about the drive end, we have always put the power out through the flywheel end. Second, he is also wrong his gear box,  a Rinker cast iron unit, undoubtably a 1.39 ratio. Since he says the engine was built 20 years ago, it isn’t going to have anything good inside,( and it stands a very high chance of being a 145 cid early engine.) This guy states that it’s an aircraft conversion because it has valve covers that say “otto” on them, but I tell him that they are just car parts from the 1970s in CA. He looks at pictures and listens to my descriptions and concedes that most of the things he said and thought about the engine were wrong. He is slowly coming to the conclusions that 1) I know something about Corvairs. 2) he doesn’t have a good engine. 3) maybe information is power, and $59 wasn’t a big rip off compared to a grand for a boat anchor.

He cheers up a little when he thinks that he might at least have an expensive core engine. I point out that it likely isn’t a 164 cid engine, and even if it was, the Rinker is mounted to the crank by broaching a key way right where we thread the safety shaft, so he doesn’t even have a core engine. He asked what he could do with it, I suggested selling it to an air boat guy. He then told me that the engine is in Idaho, not real close to the LA or FL swamps.

I am not writing this to complain about anonymous people who don’t like buying manuals but do feel entitled to complain about return phone calls. Neither am I motivated to cite another example of a person who’s only interest in Corvairs was that the thought they were cheap and he had a bargain in hand. The reason for the post is far more direct and simple: Experience has shown me that when I tell a guy who just lost a thousand dollars that what he has isn’t good, there is about a 75% chance that the specific engine will be for sale in the next 60 days on Ebay or Barnstormers for at least the same amount of money he paid. Writing this isn’t going to prevent that cycle, and there is always another guy out there to buy it. No, I write this just so when the next owner surfaces of a discussion group saying he just got a ‘cheap engine’ for his plane, perhaps one of you guys can send him a link to this story. And you know what the new guy is going to do when he finds out his engine is useless junk? Well in 60 days it…………