Brodhead Pietenpol Association

Inter-rib bracing before covering the wings is not mentioned in the plans. AC43-13 talks of the need but defers the number of braces and location to the manufacturer. Is there a standard for where they should be placed on the Piet? Any information on where to locate the bracing is appreciated.

Jeffrey,

Here's a picture of what I did. I followed the guidance of the person teaching the EAA SportAir fabric covering course at Flabob airport in fall of 2011. If I recall, this is what is recommended in 43.13.

Cheers, Ken

In theory, these ribs would be most likely to buckle midway between the spars... right where Ken has his X-bracing. Realistically though, I think with something like a Piet with lightly-loaded wings, once the wing fabric is laced to the ribs and tautened, the ribs would be held securely in their places and X-bracing would be unnecessary. But then again, the weight of the x-bracing is virtually insignificant and it does look nice and proper.

-Oscar

My understanding, which may be flawed, is that the purpose of the bracing is to keep the ribs from distorting left or right during the fabric shrinkage phase of the covering process. Since heat can't be applied across the whole wing simultaneously, there needs to be a way to keep things stable as the iron is passed across the bays between ribs.

Well that makes perfect sense!

-Oscar

Thank you all. I appreciate it.
Jeffrey K