Piet Airfoil FC-10

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Varmint
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Joined: Thu Nov 05, 2020 2:13 am

Piet Airfoil FC-10

Post by Varmint »

Some sources show the Pietenpol Aircamper as being equipped with an FC-10 airfoil.

Does anyone know if this is a "published airfoil"? Are any of the "basic parameters" (Cl Cd Cm) known about it?

I am embarking on some stress analysis and knowing the Cm would be most beneficial in the determination of the load distribution between the two spars.

OK, on that note, does anyone know of a stress analysis on the Piet already available?
Earl Brown
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Re: Piet Airfoil FC-10

Post by Earl Brown »

FC-10 (French Curve 10) is the standard airfoil designed by B. H. Pietenpol.
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taildrags
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Re: Piet Airfoil FC-10

Post by taildrags »

Varmint; I've got a bit of information on the analysis of the airfoil, published some years ago on the 'Airfoil' list on Yahoo Groups (now gone). I'll see what I can dig up. For determining the load distribution between the front and rear spars I used Evans's Lightplane Designer's Handbook (2nd Ed.) pg. 89, in the high angle of attack condition. This gives % load on the front spar as the location of the rear spar (% of chord) minus the center of pressure, divided by the location of the rear spar (% of chord) minus the location of the front spar (% of chord). Or, % Load F.S. = (RS-CP) / (RS-FS). With a wing chord of 60", front spar location centered 7-1/4" aft of the nose and rear spar location centered 36" aft of the nose, the equation resolves to % load on the front spar = 1.252 - 2.07Cp. On pg. 6 Evans has some formulae for determining Cp if you know Cm and CLmax, but obviously you don't have those. As an example though, let's say the Cp is at 30% of chord in the high angle of attack configuration. The formula then says that the front spar carries about 2/3 of the load, leaving the rear spar to carry the other 1/3.

I found an article by Noel Becar (EAA#725 in a 1960s-era edition of Sport Aviation titled "Simplified Wing Stress Analysis of a Strut-Braced Monoplane", and in Part 2, Table 2 of that article he states that in the high angle of attack condition the main spar could be carrying 84% of the total load on the wing. Some rough numbers that I was able to glean from plots of airfoils similar to the FC-10 got me Cm and CLmax numbers that resulted in a number more like 90-92%, so in some of my articles in the BPA Newsletter on the subject, I used 95% to provide an extra factor of safety when analyzing the required strength of the front spar. Several other articles that I've written on analysis of various parts on the Air Camper have also been published in the BPA Newsletter over the last couple of years, such as the lift struts, their attach fittings, the steel straps that cross under the floor, and several configurations of wing spars. Guaranteed to set most readers into a good deep sleep, but a few of us out here like to play with numbers and trigonometry ;o)

Oscar Zuniga
Medford, OR
Air Camper NX41CC, A75 power
tom kreiner
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Re: Piet Airfoil FC-10

Post by tom kreiner »

Gents,

Ten or so years ago, I came across the attached by one D. Michael Shuck. Don't know where to locate the elusive Dr., but his paper is background for a lively discussion regarding the FC-10 airfoil.

Enjoy; be sure to make yourself comfortable prior to reading!

TK
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Commentary_on_the_Pietenpol_Airfoil.doc
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KenBickers
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Re: Piet Airfoil FC-10

Post by KenBickers »

Tom, thanks for posting this article. I'm looking forward to reading it with a piping cup of coffee. I love this sort of paper. Cheers, Ken
Varmint
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Re: Piet Airfoil FC-10

Post by Varmint »

Thanks guys for your input. Yeah, that's the kind of info I'm looking for.

Oscar, do you by chance have the article by Noel Becar still, or a link to it. I googled it and found a link, but it is no longer active.

I've read your articles on the strut attach and the various spar types. I've not see the ones for the strap across the fuselage or the struts themselves. Could you direct me to which issue of the newsletter they were in? And any other similar articles you may not have mentioned above?

Thanks
Varmint
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Re: Piet Airfoil FC-10

Post by Varmint »

Update: I found a pdf of Noel Becar's article. I can provide it to anyone who is interested.
tom kreiner
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Re: Piet Airfoil FC-10

Post by tom kreiner »

Varmint,

Please reply and drag the article into new reply so we can all enjoy it!

Thanks,

TK
Varmint
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Re: Piet Airfoil FC-10

Post by Varmint »

OK I think it is attached here
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Simplified Wing Stress Analysis of a Strut Braced Monoplane.pdf
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taildrags
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Re: Piet Airfoil FC-10

Post by taildrags »

The writeup by Mike Shuck is exactly what I was referring to. Mike moderated the Airfoil group on Yahoo Groups and that's where I first read his excellent writings. I know exactly where he is, a family medical practitioner in Wichita Kansas, but I also know that he's a busy guy and that he copyrighted the article and has not given me permission to do anything with it. He states that it is his intention to compile a number of his entertaining and informative articles into a book, so I'm not using them for anything other than for source material for my own education and enlightenment. He's a good guy and a Piet lover.

-Oscar
Varmint
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Re: Piet Airfoil FC-10

Post by Varmint »

It was a good article and had more of just the info I was seeking. Although it did not show any negative angles of attack. Not much of a concern in cruise, climb and landing performance, which he dealt with. But would be helpful to calculate the negative lift distribution on the spars, and thus the compression of each of the struts.
doug bryant
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Re: Piet Airfoil FC-10

Post by doug bryant »

i know mike shuck well here in wichita. he comes by the shop frequently to check my piet progress.
Varmint
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Re: Piet Airfoil FC-10

Post by Varmint »

Maybe if Mike still has the FC-10 foil data modeled in his computer he can run the negative AOA numbers with no real effort.

I come to Wichita a bit on business trips with "down-time" in the evenings. Perhaps I can come by and see your project....
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taildrags
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Re: Piet Airfoil FC-10

Post by taildrags »

Now, see-? THIS is the value of these groups! Meet other builders and pilots, ask questions, share ideas, "harvest" tips and tricks from others, and network/connect. Although I had been flying for 30 years when this happened, I never gave the Air Camper a thought until the day I met Ernie Moreno and visited his hangar. There it was! And I got to sit in it! And it was love at first sight! This was 20 years ago, and although my hair has gone grey and the mustache is now gone, the smile isn't!

-Oscar
Pb030027.jpg
doug bryant
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Re: Piet Airfoil FC-10

Post by doug bryant »

sure visit any time. number is 316-250-7013
Varmint
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Re: Piet Airfoil FC-10

Post by Varmint »

OK Doug I'll give you a call next time I'm going to Wichita. Probably will not be until around June.
doug bryant
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Re: Piet Airfoil FC-10

Post by doug bryant »

ok, great
Varmint
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Re: Piet Airfoil FC-10

Post by Varmint »

Oscar mentioned articles in the newsletter analyzing the wing struts and the tension strap that crosses the fuselage between the lift struts.

Does anyone know which newsletters those articles were printed in?

Thanks
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taildrags
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Re: Piet Airfoil FC-10

Post by taildrags »

Varmint: email me at taildrags@hotmail.com and I'll share those articles with you.

-Oscar
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