Last engine of Corvair Finishing School #5:

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It’s Sunday near sundown, and I type this to the sound of Bill Hutson’s 3,000cc Corvair putting down a perfect test run outside. His Engine is destined for his Zenith 750 STOL.

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Bill puts in the last checks on his 120HP Corvair. Friday night it was all perfectly prepared parts, now it is a running motor; but the real transformation is what he understands about every part inside. 30 years of doing this, and the moment a builders engine fires up, where his learning is confirmed, never gets old.

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WW

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Myths and Misconceptions in the world of Pietenpols

Builders,

Because there is no “Factory” associated with the 90 year old Pietenpol design, the transfer of experience and ideas to new builders flows through many places, predominately social media. A really large chunk of this info is harmless, but some of it is not. Myths and misconceptions are shared and spread by often well meaning people who mean no harm, but they cause it anyway. The harm ranges from the lost opportunity for the recipient to actually learn something, to sending people on a time and money wasteful detour that leads to many people quitting, straight on through encouraging people to fly with passengers in aircraft that are unairworthy, by a standard Bernard Pietenpol himself stated.

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The number #1 way you can tell you are looking at “an opinion” , not a piece of data: It is delivered without a reference, and particularly without testing nor personal observation. If someone chimes in to say “Lean the cabanes back, it will be alright This is a near worthless opinion. If someone says “I have the same engine on my flying plane, N 177XW, my wing LE is 4.25″ aft of the firewall, my EWCG is 10.3″ and my EW is 737 pounds, it is in CG with a 194 pound pilot” , this is a useful piece of data to work with. The Weight and Balance data provided by Ryan Mueller and myself is that kind of data, for 20 different planes. Yet, some people will proceed down the building and flying path, armed only with opinions and no data.

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Some questionable ‘advice’ comes from people with flying planes. Its not bad data, but it is often not applicable to a different engine, or different size pilot. Much of the time, it is delivered as “This worked great for me” which is fine, but it doesn’t address the question, ‘Is this the best way it could be done on the new plane being built? This is most commonly done with CG comments. A person reporting that the plane flies ‘good’ at the aft CG limit, almost never has personally flown one near the front limit, far less flown the same plane, the same week, on each end of the limit. Enter the photo below:

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My Pietenpol, 1996, Edgewater Florida. The reason why the cowl has a 6″ wide expansion in it is simple. I carefully measured, and in a single day, made a mount 6″ longer and plugged the cowl for test flying. In the picture is Gus Warren who did a lot of the work with me and covered much of the flying. It was an instant improvement in safe flying behavior. I can comment on the difference between the same plane flying at 15″ and at 20″. This is what testing looks like, and this produces data, not opinion. Read more here: Evolution of a Pietenpol and here: Evolution of a Pietenpol pt. 2

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Common Pietenpol Construction Myths:

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“Having threaded sections on the diagonal cabanes will allow the plane to have the CG corrected later.” This is a myth. Study the weight and balance articles, and understand that many builders missed their target by several inches on the wing position. The articles show that moving the CG just 1″ requires moving the wing 1.3″. Builders need to just study examples of planes close to theirs, make a calculated fine tuning adjustment in the wing position, and make the diagonal cabanes rigidly attached to the front vertical cabanes.

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“I did a W&B measurement on my plane and it is 1.5″ from the aft limit, it will be fine when it is covered.” This is a myth. If you look at just the covering on the wing with its 60″ chord, the weight of the fabric on it will logically be near 30″, and this is 10″ behind the aft limit. Now think about the fuselage, which has almost no covering ahead of the front cockpit, but a lot of it 6′ aft of the wing, and then there is all the tail surfaces, all the way back. The covering on a Piet can easily weigh 35-40 pounds, and nearly every bit of it is going to drag the CG backward. The effect is strong, and not easily countered. A W&B check when uncovered is not a substitute for a plan right from the beginning.

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“Having an axle location near the wing leading edge will make the plane hard to fly” This is a myth. Look at the 35,000 American certified light planes which had tailwheels made in the 1940’s and they all have the axle close to the wing leading edge when they are in the flight level attitude. No one speaks of these aircraft as hard to fly.

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“Having the axle a few inches further back can’t make much of a difference in the plane’s potential  to end up on its back” This is a myth. Ask any person who knows what a Cessna 120/140 axle extender is. Before them, if the Goodyear brake jammed a disc (an issue on floating discs) many planes ended up on their backs. This modification moved the axle a few inches forward, and very effectively prevented the airplane from going over, even with a locked brake on pavement.  A few inches difference on axle placement makes a big difference. One of the few light planes of the 1940s to have the axle a few inches back from the leading edge is a Luscombe, and these are the most common light plane to go over.

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“My buddy Mongo has brakes on his A65 powered Pietenpol, the axle is 10″ back from the leading edge and he says it never feels like his plane is going to nose over.” This is a misconception. The reason why this isn’t good data because it fails to mention that Mongo weighs 265 pounds, and he is flying with the CG several inches behind the aft limit. On any plane operating within BHP’s specified CG limits of 15-20″ having brakes on an axle located 10 inches behind the leading edge in an open invitation with a filled out RSVP to put the plane on it’s back.

 

A few words on wood:

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in 2010, I took this picture of the awning outside BHP’s shop in Cherry Grove. The frame had been there 8 years earlier, on my first visit, and I suspect it was BHP’s personal work. You have to appreciate the values of a man who ended up with an apparently straight aluminum Piper spar and thought that its best use was an awning frame. If you look closely at the photo above, you can see the diagonal bolt holes where the lift strut used to be attached.

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OK, BHP liked wood so much he thought aluminum wing spars were good for awning frames. So why didn’t any of his planes have wood lift struts or wood cabanes? This is a question you should really ask yourself before using wood on your plane.

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I have all the volumes of Juptner’s “US Civil Aircraft” , it catalogs in detail, the first 800 aircraft certificated in the US. Volume one starts in 1927, when BHP’s was testing his first ideas. I have scanned it quite closely, and I don’t see any aircraft with wooden struts. I suspect that once metal airfoil shaped tubing became available, no one thought of using wood anymore.

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People always point out that WWI biplanes had wooden struts, but they almost never have considered that the interplane struts on a biplane are always in compression, and they are almost never longer than 4-1/2′. There are also dozens of biplanes in “US Civil Aircraft” , and none of them use wood struts.

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Wood has obviously worked before on Pietenpols. The issue I have with it is how people choosing wood struts gloss over that these are not in the plans, and they often downplay variations in the wood and the difficulty of drilling precision holes in wood to match the fasteners. I understand why people like the look, but you honestly have to ask yourself is appearance a valid reason the deviate from the plans, the most common material, and to do so with little or no engineering.  Think it over.

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William.

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Corvair Open house, this Saturday (6/29) Noon-6pm, At the SPA/Panther Factory.

Builders,

This Saturday, between noon and 6pm, we are having a joint open house at the panther Factory in Green Cove springs Florida. If you would like to stop by and see some engine runs, get a look at completed motors and parts, meet the gang and tour the factory were Panthers are made, this is a great opportunity.

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SPA:

Phone:  904.626.7777

Address:

1528 Virgils Way, Ste 8

Green Cove Springs, FL 32043

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 Get a good look at David Koshinski’s smiling mug. This is the face of a very happy man. His engine was one of the runs at the 2018 Panther open house day. What produces this expression? The satisfaction of having an engine that you built with your own hands, an engine you really understand,  lay down a perfect break in run. This is what the very core of traditional homebuilding is all about.

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Hope to see many of you there.

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William.

Pietenpol Cabane struts, Part #3

Builders,

This picture tells a story of diagonal front cabanes on Pietenpol aircraft.

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The picture above is from 2005, It is the late Bill Knight, flying the last Pietenpol ever built by Bernard Pietenpol. It is known as “The Last Original”, and several people have had stewardship of this treasured piece of homebuilding history in the decades since BHP’s passing Bill kept it the last 15 years of his life, and much of this time made it readily available to any builder who wished to study the last evolution of the master’s design. I spent many days studying it, and the details tell quite a story of how Bernard thought.

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The particular part I draw your attention to is easy to see in the picture: the diagonal cabane struts. Notice that they are the same size as the vertical ones, and they are welded to the top of the front cabanes. There is no adjustment here, BHP was prioritizing strength and rigidity at this point in the evolution of his design.

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Way too many of todays builders are using the tiny round 1/2″-035″ tubes shown in some pre-war plans. As I have discussed, these are way too small, and prone to failure in an otherwise inconsequential mishap. When I pointed this out on the internet, a guy who has a flying Pietenpol and is an accomplished pilot, but has tiny round diagonal cabanes on his plane said “I built my plane to fly, not to crash.” The picture above shows that Bernard Pietenpol didn’t see it that way. I drive my pick up for transportation, not to have an accident, but I still have seat belts in it. Maybe your car does also.

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The things I speak of on Weight and Balance and Cabane struts are read by builders, but there are a small number of people, who have been around the Pietenpol community for a while who reject these things because the mistakenly think they are my ideas. These are not my ideas, they are straight from BHP himself. The ‘holy grail’ weight and balance sheet was typed by BHP himself, and the cabanes in the picture above were fabricated by the hands of the man.  These are not my ideas, I just spent a lot of time looking at his work, and I’m only pointing out things he already share with builders a generation ago, things which unfortunately have taken a back seat to discussions of house paint, brass ornaments, saw blade brakes and other appearance items which may be fun, but none of which appear on the The Last Original. 

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wewjr.

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Video on Parasol structures, Part 2

Builders,

The  part one of this video pair was viewed 425 times the day it was posted on my Youtube page. Not world record setting, but still very popular by my standards. It was well received on Pietenpol sites. Here is a follow on which expands a bit on the original ideas explained in round one.

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https://youtu.be/LDc3ebujobk

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Because of how I collected the photos, some the images are not going to be high definition. I apologize in advance, but I wanted to get the conceptual information into the discussion as a quick follow on to complete the discussion on the structure of parasols.

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If you like this kind of video and how the subject is covered, use the comments section here, and please subscribe to my youtube channel.

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Note to builders of Pietenpols with other engines:  There was a comment made on the Pietenpol FB page about me “Withholding Information” about the construction of  Pietenpols from builders who choose engines other than Corvairs.  This is pure BS, and it is a fake claim.  The two videos in this series benefit all Piet builders, posting them on youtube publicly hardly is withholding them. Likewise, All of the data I developed years ago with Ryan Mueller on the weight and balance of Pietenpols with all kinds of engines was shared with everyone through the newsletter, and will shortly be available in notebook form through the Brodhead gang. I have never refused to help any builder with any aspect of his Pietenpol, no matter what engine he chose. Every article I ever wrote about Pietenpols has always been publicly available here: Corvair – Pietenpol Reference page.   I’ll share what I know with just about anyone, no matter if they are a Corvair builder or not, even people I find distasteful; my devout allegiance to aviation safety isn’t conditional on being paid nor finding people pleasant, it is about protecting unwitting passengers who will inevitably fly in these planes.

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The only thing we do privately is our “Piet-vair” Discussion Group where we talk about Corvair specific things. Anyone suggesting I have ever withheld safety information from another homebuilder is making and incredibly offensive false statement.

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wewjr.

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Video: Motivation, and the mindset of Homebuilders

Builders:

Zenith 601XL/Corvair builder and flyer Phil Maxson was here at my place in Florida earlier in the week. In addition to catching up, we shot the Oil change video, and took a few quiet moments to catch this interview style video in my back yard.  Part of the reason the topics came up was Chris Welsh, my roommate from Embry-Riddle was present, and the three of us had spent the previous evening kicked back and covering some of the same terrain.

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The Video is a lot broader in scope than the subject of Corvairs. If you have someone in your life who is yet to understand what you are pursuing in your workshop, perhaps a link to this video will shed some light to your mindset.

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https://youtu.be/DmTuBQpjl34

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Above, the link to the 25 minute interview. If you have never met me in person, here is a view of what a morning in my backyard actually looks like, perhaps very different than you might guess from just following my writings. We cover a number of topics, including the original of modern Corvair building, my evolution to the mindset of a homebuilder, and the values of mastery vs ownership.  Its not quick, if you are pinched for time, save it for a time where you can watch it sitting down with a coffee or a beer.

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If this kind of discussion is not to your tempo or temperament, just pass it. It doesn’t have any technical info in it, just ideas and thoughts.  Phil and I are prone to considering things as if we are H.L. Mencken and George Jean Nathan out on a road trip to ‘take the national temperature’. 

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wewjr

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Video on ‘Parasol’ Structures 101

Builders,

Today I received a number of questions asking for a bit of clarification on last nights Pietenpol story. In that story I tried to explain some of the planes issues.

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 If you are real new to aviation, a ‘Parasol’ is an airplane configured to look like a biplane without lower wings.  Just after WWI, this was the configuration of choice for front line combat fighters. It persisted into the 1920s, and they were the bridge between biplanes and cabin monoplanes. The most famous one today is the 90 year old Pietenpol Aircamper, but over the years, there have been a number of classic homebuilts with this configuration, and some factory built beauties like the Fairchild 22.

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In the interest of sharing some info which all Piet builders should understand, , I made a quick video using a ugly balsa representation of a parasol. The esthetics shouldn’t deter anyone from understanding the concepts.

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https://youtu.be/85mnnWOjFKI

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Note, I was tired when I shot this, I did it in one take, and without any kind of a script. I just had a phone call where I was explaining the difference between compression and column bending to a builder who was asking about jury struts. Twice in the video I mistakenly say column bending instead of compressive load. Just ignore it, thanks.

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If you have any comments or questions on the video, please share them here. If you have not yet, please subscribe to the Youtube channel. Having 1,000 subscribers will allow us to put links to stories directly in the video comments.

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WEWjr.

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Corvair Oil Change Video

Builders:

Our next video is up, here is a direct link, please use the comments section here to share thoughts and ask questions.

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ttps://youtu.be/Op3SNmeFTz4

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Above the link, the image above is Phil Maxson pouring the oil in his plane here in Florida yesterday. It is a great feeling in life to have friends like Ken and Phil, and to do projects like these videos with them. Over three decades of working with Corvairs, I have had a lot of fun moments with good friends, some here, some now gone, but this stuff we have done this spring is a match for any of the previous good days.

 

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We are more than half way to the 1,000 subscriber goal. Please take a moment when on youtube to join my channel. You will be informed of every new video when it is up.

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Thank you, wewjr.

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Need Help Contacting the Builder of this Aircraft ASAP.

Builders,

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

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

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

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

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

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

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

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

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

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wewjr.

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Oil Pressure Regulator Video

Builders:

Here is a video in oil pressure regulators. This is a sub component of HV-2000 Rear Oil Cases

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https://www.youtube.com/watch?v=-cd_jwZRz3A&t=7s

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If you would like to read a lighthearted story about oil cases, check this out: Jack-o-lantern parts cleaner for HV-2000 rear cases., it contains the quote:

For all of you childhood pyromaniacs and unrepentant troglodytes trapped in repressive gated communities, those in apartments with pleasant neighbors and  builders exiled to places with property owners associations run by yuppies, gaze upon the Jack-o-lantern cleaner and imagine horrifying all of those that would repress your most fundamental pyro-mechanical instincts.  It isn’t just a cleaning tool. When surrounded by fun people drinking beer it is a down right declaration of motorhead independence and freedom.”

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If you like the video material, please remember to subscribe.

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wewjr.

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