rcbif
09-24-2019, 04:49 AM
I rigged the wing of my model 5 last night, but I have to say, the only step I’m not 100% sure of the intent of is the first step in setting wing twist. The manual has you place the level, 3” from the root, place the level touching the front spar, and measure the difference between the level and the bottom of the rear spar.
Both my wings were level for this location, and being so close to the fuselage, I’m not entirely sure why they shouldn't be?
The only reason I can come up with the purpose of this step is if for some reason your spars are floating a bit over the fuselage lug/attachment points? Is this sound reasoning?
Regardless, I proceeded to measure level at the wingtip with my ½” block on the level for the ½” washout.
This morning I decided to review the same steps in the model 7 manual the previous owner bought for this model 5 to reference for some updates and I noticed the model 7 uses a different reference for the dihedral.
The 5 uses the rear spar to measure the 1 deg dihedral, while the 7 uses the front spar to measure the1 deg dihedral.
This is followed by the 5 adjusting the front lift strut bracket position to set twist, and the 7 adjusting the rear lift strut bracket position.
I would think the leading edge would be the logical place to measure dihedral, and I’m guessing that’s why Kitfox changed it to that way, but I’m no aeronautical engineer.
I ran the numbers (scary trig, lol) and the difference would be .17 degrees in dihedral. So the 5 has a bit less. I think since I already rigged according to the 5 manual, I’m just going to go with that unless anyone has any comments.
Both my wings were level for this location, and being so close to the fuselage, I’m not entirely sure why they shouldn't be?
The only reason I can come up with the purpose of this step is if for some reason your spars are floating a bit over the fuselage lug/attachment points? Is this sound reasoning?
Regardless, I proceeded to measure level at the wingtip with my ½” block on the level for the ½” washout.
This morning I decided to review the same steps in the model 7 manual the previous owner bought for this model 5 to reference for some updates and I noticed the model 7 uses a different reference for the dihedral.
The 5 uses the rear spar to measure the 1 deg dihedral, while the 7 uses the front spar to measure the1 deg dihedral.
This is followed by the 5 adjusting the front lift strut bracket position to set twist, and the 7 adjusting the rear lift strut bracket position.
I would think the leading edge would be the logical place to measure dihedral, and I’m guessing that’s why Kitfox changed it to that way, but I’m no aeronautical engineer.
I ran the numbers (scary trig, lol) and the difference would be .17 degrees in dihedral. So the 5 has a bit less. I think since I already rigged according to the 5 manual, I’m just going to go with that unless anyone has any comments.