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Landing Gear Lift Strut Attachment Angle

Bucrepus

Registered User
Getting Advice ! What angel should the lift strut attach bracket be welded to the lower longerons? The Strut attach fitting on the wing is set to 21* 45' (21 degrees . 45 minutes) should the strut attach fitting on the fuselage be set the same? I've been told to set it at 22.5* decimal angel. ( 22 degrees. 30 minutes)
 
This is a collection of drawings: http://www.supercubproject.com/drawings/
Drawing 20671 appears to answer your question. It looks like the answer is 12 degrees.

edit: Where did you get "fitting on the wing is set to 21* 45' (21 degrees . 45 minutes)"?
Simple geometry says it should be 12 degrees minus the dihedral angle of the wing. All the angles of a triangle add up to 180 degrees.
 
Last edited:
Skywagon8a

The drawing 14383 ( Front Spar Drawing ) gives reference 21* degrees , 45" minutes for mounting Spar Attach fittings.
 
Since the strut fitting is also the rear gear fitting you should fit the gear first and make sure that it's in alignment before worrying about the strut attach angle. Most builders I've worked with set the gear alignment by the gear fitting location on the lower longeron and then when the strut install happens they just change the angle of the strut fitting as necessary by cold bending it with a big open end wrench. Not a whole lot of science in cub engineering.
 
Thanks Crash !
That's along the lines of thinking I've been having. I was just trying to get things as close as possible and tack weld the fittings in place. I've went through the calculations and I believe that 22*30' is a good starting point if you take into account of the 21*45' angle for the strut attach bracket on the wing and the factor in the dihedral. I did notice last night I was out just out a frogs hair between left and right attach points of the landing gear. Ill start building my gear tonight and find my open end wrench.
 
In 2017 when I built my new fuselage in a good jig, I got the fittings tacked so that the gear fit properly and the angle came out (for this fuselage) at just a little under 23deg. and required no adjustment when the struts went on. FWIW
 
I believe we have found an error in Piper's drawings. Dwg #20671 calls for 12 degrees. The matching part Dwg #20681 calls for 20 degrees.
 
Drawing 12183, figure 12, shows the angle at 22.5 degrees.

Thanks Mr.Ed
That's Fig 12 Drawing on the Northland Drawings. I see ! If you look at the Piper Drawings there is no degree angle. I believe the 22.5 Degrees decimal is the correct number.
 
I believe the degrees on parts 20671and 20681 are just starting points to allow for final forming on the fuselage. Just my thoughts but I'm not an expert. LOL
 
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