Split gear fitting plans question

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PoconoJohn
Posts: 165
Joined: Tue Jan 14, 2020 9:07 pm

Split gear fitting plans question

Post by PoconoJohn »

On the plans, it shows the 2" wide metal strap (which I'm using) below of the floor. It doesn't show the fitting mounted on it, rather, makes it look like the strap becomes the fitting, which I believe is not the way it goes (especially since the fitting is 2 1/2" wide and the strap is 2").

So overall, confused at the part where the strap enters from the left, encounters a "weld" section near the 3/16" bolt, and then a small space prior to the lug.

Questions:

1) does the metal strap run from the left and right edges of the outer plywood?
2) does the fitting get welded to the metal strap?
3) If I weld to the metal strap, then the outer fitting (which is bent 110 degrees) will be just a little lower than depicted. I assume I'll have to make the vertical part (labeled #1) longer to make up the difference.

Thank you,

John C
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KenBickers
Posts: 128
Joined: Tue Mar 07, 2017 7:00 pm

Re: Split gear fitting plans question

Post by KenBickers »

John,

I spent a fair amount of time trying to figure out this exact same thing. My split gear was gifted to me (thank you Oscar) after my Jenny-style gear was destroyed in an off-field landing. The split gear did not have the straps at the time.

I ended up butt-welding the 2" straps to the ends to the inside edge of the gear attach fittings. I didn't weld a single piece across the two. Instead, I welded a strap to each gear attach fitting so that they would overlap mid-fuselage by approximately three inches. I then drilled a pair of 1/4" holes and used AN bolts through the overlapping straps and the ash cross member on the inside of the fuselage to hold the straps together as a single unit.

Perhaps there were other, better approaches, though I don't know. That's what I did.

Cheers, Ken
PoconoJohn
Posts: 165
Joined: Tue Jan 14, 2020 9:07 pm

Re: Split gear fitting plans question

Post by PoconoJohn »

Thank you. I'm thinking of making the fittings, then running the strap between them, meeting the ends (butt them). I'll weld a piece of steel over both the left and right side seams; I think that's what the weld area in the drawing is. Reading the text again, it does say "between fittings"

John C
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taildrags
Posts: 637
Joined: Tue Mar 07, 2017 10:39 pm

Re: Split gear fitting plans question

Post by taildrags »

I think it's been shown both from the plans and from anecdotal comments received from people who knew and worked with Bernard Pietenpol that the strap between the gear/strut attach fittings running under the belly is not a critical structural element. Drawing No. 3 of the Hoopman plans notes that the strap is "for extra strength only (not necessary for ordinary use)". Anecdotally, Mr. Pietenpol had a steel yardstick in the shop that he had gotten from a hardware store and used that for the connecting strap. If that's the case, then the exact thickness/gauge of the metal isn't of vast importance and neither is the means of attaching it.

I would be interested to know if there has ever been a documented failure of that strap and if so, under what circumstances.

Oscar Zuniga
Medford, OR
Air Camper NX41CC, A75 power
PoconoJohn
Posts: 165
Joined: Tue Jan 14, 2020 9:07 pm

Re: Split gear fitting plans question

Post by PoconoJohn »

Thanks Oscar. I saw the note about the strap being optional and decided to install it anyway. It's extra weight I know, but I like the idea of more strength at those white ash points.
jeffreyK
Posts: 43
Joined: Wed Jan 15, 2020 9:41 pm

Re: Split gear fitting plans question

Post by jeffreyK »

Good question. I will aslo soon be done with my gear brackets and have been studying that steel brace. I agree it looks like the steel strap is in line with the brackets and a cover plate is welded to both at the joint. That said; in the WW blog is a write up on some gear brackets that were made which have the steel strap running the width of the fuselage and the brackets are welded over it.
There was an extensive article with data regarding the loads on the strap and the White Ash Crossbar in the BPA newsletter 2021-02. It's a good read and if I read it correctly; suggests that from an engineering viewpoint you don't need the strap. The plans also state it is optional. With that we all have to make our own decisions.
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