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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