strut attach fitting angle

[John Slaughter]

Does anyone know why the plans show an angle of 20 degrees for the strut attach fittings on the fuselage? The flying struts form an angle of 30 degrees (up) at the fuselage. Pics seem to show fittings with 30 degrees, nut I don't remember seeing this addressed. Help much appreciated, John Slaughter

[Richard Roller]

N34KP has the strut attach fittings as drawn on the plans, with plywood strips on either side of them, That is how Ken Perkins built it. It's worked fine for 20+ years now. Personally, when I built one I will attach them inline with the struts.

[John Slaughter]

Hello Richard- Thanks for your reply. I don't quite understand "plywood strips on each side" unless you are referring to the strut fittings on the spar. My question is about the other end of the strut, at the fuselage. The plans for the steel landing gear- strut attach fittings show a 20 degree up angle, while the strut goes up to the wing at about 30 degrees. Isn't it better for the strut attach tabs to line up with the axis of the strut? I haven't seen this discrepancy discussed anywhere, and would like to hear your thoughts.

[Richard Roller]

My mistake! Yes, you DO want your strut tabs lined up with the strut angle!

N34KP has it's strut tabs on the fuselage bent to line up with the actual strut angle. I was just looking at my set of plans and I don't see any angle noted. Ken bent his to the angle needed to be in line with the struts, as I said above. The next time I'm at the hanger I'll try to get a picture of the construction, he did his a little different from the plans.

On my project the included angle is 31 degrees.

[John Slaughter]

Thanks much-looking forward to the pics. This "downhome engineering" is one of the best parts of Piet-building- you have to keep thinking, and it really helps to have people who were once strangers come up with answers!

[Richard Roller]

Phone photos. When clicked on they will be upright. This is the right side, forward strut attach point.

[John Slaughter]

Nice pics. Looks like a faithful following of BP's plans. I'm welding my gear up using an idea of William Wynne and Earl Brown- definitely heavier, but stronger as well. A good set of pictures of Earl's gear can be found on the Pietvair forum- it's kind of quiet these days, but still lots of good stuff for when you pull the trigger on your build (the "vair" refers to Corvair engines.). John

[Richard Roller]

I'm sure you noticed, but Ken didn't use the steel straps from side to side (fitting to fitting) shown on the plans. He didn't think them necessary.

This last spring while I was finishing the repair to the tail longeron, I pulled the landing gear/lift strut attach fitting bolts out, one at a time. The bolts and holes were in good shape with no sign of elongation of the holes in the wood or metal. As in the tail I found that the finish on the bolts was corroded off and there was some minor pitting on the bolt shanks. This happened even though the holes in the wood are epoxied. So this winter I will replace them all.

[John Slaughter]

I am certainly going to use the 2 " straps (.090"). As far as fastenings through wood are concerned, my woodworking background is in boatbuilding, where everything is "bedded", usually with a polysulfide ("Boatlife" or similar), which will protect both wood and fastener shank. I plan to do this, but haven't seen any thing mentioned about it on aviation sites.

[Richard Roller]

Yes. While I was still working on large a/c we always used the aviation equivalent to your polysulfides, patches, hardware, etc. When I worked small a/c you didn't see it much, except in fuel tank areas.

Personally, I think it would be a good idea on a wood a/c.