Pietenpol Weight and Balance manual – Video

Builders:

Here is a video introducing our new Pietenpol Weight and Balance Manual:

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https://youtu.be/5ukNBFOU7rM

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Im going to be at Brodhead, the Pietenpol Gathering, just before Oshkosh. The BPA newsletter people will be offing copies of this manual to builders. I elected to do this as a contribution to the Piet newsletter and the Brodhead events. I will also have copies at Oshkosh, and after we return it is be a normal catalog item.

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If you like this kind of information, please take a minute to subscribe to the youtube channel.

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thanks,

WW.

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The humorous  part of my work: 

Pietenpol builders have a pretty active Facebook group, it isn’t very technical, but it is a way for that building community to share news. This said, it can have many of the same issues as other groups on the web.  When this new manual was first mentioned there, one guy made a comment that he felt I ‘withheld’ Pietenpol info from non-Corvair builders. A few days later another guy was saying that the manual was too long and no one needed such information. Kind of a contradiction, seems I can’t really be guilty of both at the same time.

I actually spoke to the guy who made the first comment on the phone for 30 minutes last week and everything is fine, just a poor choice of words. Second guy probably just likes attention. I’m guilty of this also but I try to earn it with something useful like this manual, not sarcastic comments about other peoples projects. As a builder, none of this matters to you, its all dumb drama. In a week we will be among friends having a good time up north, and I will be glad to speak with anyone in person about their Pietenpol’s W&B so they can build and fly a better plane. 

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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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