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Horizontal stab tube size and diameter? Problems with play in mount...

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Hey guys,

since I rigged my Ultimate two days ago to tack weld the wing mount brackets I wanted to tack the rear horizontal stabilizer attach tubes as well.

Unfortunately I found that the tubes of the elevator and horizontal stabilizer seem to be too big for the tubes that go on the fuselage. I checked the drawings - the parts are all build as per plans, no issue here.

The dimensioning is as follows:

1. Leading edge tube of the horizontal stabilizer: 7/8"*.058 (Splice welded tube piece for the exact purpose of fitting over the tube of the fuselage, the leading edge itself is 3/4")
=> So inner diameter is 0.759" or 19.278 mm

2. Trailing edge tube of the horizontal stabilizer: 7/8"*.035
=> So inner diameter is 0.805" or 20.447 mm

3. Leading edge tube or the elevator: 1"*.035
=> So inner diameter is 0.930" or 23.622 mm

The above mentioned tubes have to slide over the following tubes or bearings, 1 goes to 1, 2 goes to 2 and 3 goes to 3:

1. Front horizontal stabilizer attach tube (boltes and shimmed in place): 3/4"*.049
=> So outer diameter is 0.750 " or 19.05 mm

2. Rear horizontal stabilizer attach tube (welde in place):
3/4"*.049
=> So outer diameter is 0.750 " or 19.05 mm

3. Elevator bearing KP4:
=> Outer diameter is 0.9014 or 22.896 mm


This means, that I have the following clearances:

1. 0.009" or 0.23 mm
2. 0.055" or 1.39 mm
3. 0.028" or 0.71 mm

Well, No. 1 is acceptable in my oppinion. But No. 2 and 3 can't work.

What tube sizes are used on the Pitts models? The setup is the same. Hopefully someone can enlighten me - for now I'm pretty frustrated. Hoped to be able to make some progress on the build, but now I'm only thinking about how to solve this problem. I for sure won't weld anything in place that hasn't a perfect fit.

I absolutely appreciate your support! Thank you for every single oppinion.

Wishing you a merry christmas and a happy new year ahead!
 

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