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True the additional clearance to insert a Z bend in the hole would not matter that much on a tow release since either it does or doesn't. But when I see them being used on aircraft for controls like the elevator and ailerons I cringe. Probably my OCD kicking in again. I just saw it as a good segway to discuss control linkages and a little about servo set-up.
OOH, another good point about horns on servos. I try to have the rod to hole lateral lines form as close to a 90 degree angle as possible when at center. This prevents mechanical differential to be introduced in the linkage system. Many know this, but I have seen many aircraft with it on controls like the rudder, not good IMO.
Sometimes I intentionally set up the linkage with mechanical differential though such as flaps that are used for glidepath control with inboard aileron mixing where one needs more down than up. Just all good setup tips that should be used on every airplane. However, computer radios have allowed many to get lazy by punching in some numbers and not take that care in their installations.
Most of what I mentioned applies to what we have learned flying our very thin wing competition gliders on monofilament lines. F3J is a class that has a 100 meters to the turnaround pulley line length , here half of which is mono on a winch, at the World Championships it is all mono towed by two strong quick people. F3B is a class where the line is 100 meters all mono on a winch. Monofilament when under tension can store a great deal of energy!
For those that fly in these classes many try to have all of the push rod linkage internal to the wing, which results in a very short horn set-up both on the servos and very short ones on the surfaces. This requires precise sizing of the pivot point holes. I use a #53 number drill for this and after the clevis pin is inserted and the horn rotated by hand a few times it is a snug rotational fit. If there is any slop in the control system then flutter can occur in the dive and pull out when releasing from the line to gain that extra energy. Not pretty as many airplanes have been destroyed that way... VNE reached rapidly on that airframe!
An amusing comment I remembered last night relating to trying to transpose 2D into 3D in one's mind. Shortly after hiring in at the company where we modified aircraft I was on the manufacturing floor supporting one of the assemblers about a plan I had composed. He mention he had to stop work on the assembly and wait for an engineering change as the parts would not fit together. The engineer came down and saw the assembly for the first time in 3D and said when looking at it, "well it worked in CAD." Remember to honor our Veterans today.
OOH, another good point about horns on servos. I try to have the rod to hole lateral lines form as close to a 90 degree angle as possible when at center. This prevents mechanical differential to be introduced in the linkage system. Many know this, but I have seen many aircraft with it on controls like the rudder, not good IMO.
Sometimes I intentionally set up the linkage with mechanical differential though such as flaps that are used for glidepath control with inboard aileron mixing where one needs more down than up. Just all good setup tips that should be used on every airplane. However, computer radios have allowed many to get lazy by punching in some numbers and not take that care in their installations.
Most of what I mentioned applies to what we have learned flying our very thin wing competition gliders on monofilament lines. F3J is a class that has a 100 meters to the turnaround pulley line length , here half of which is mono on a winch, at the World Championships it is all mono towed by two strong quick people. F3B is a class where the line is 100 meters all mono on a winch. Monofilament when under tension can store a great deal of energy!
For those that fly in these classes many try to have all of the push rod linkage internal to the wing, which results in a very short horn set-up both on the servos and very short ones on the surfaces. This requires precise sizing of the pivot point holes. I use a #53 number drill for this and after the clevis pin is inserted and the horn rotated by hand a few times it is a snug rotational fit. If there is any slop in the control system then flutter can occur in the dive and pull out when releasing from the line to gain that extra energy. Not pretty as many airplanes have been destroyed that way... VNE reached rapidly on that airframe!
An amusing comment I remembered last night relating to trying to transpose 2D into 3D in one's mind. Shortly after hiring in at the company where we modified aircraft I was on the manufacturing floor supporting one of the assemblers about a plan I had composed. He mention he had to stop work on the assembly and wait for an engineering change as the parts would not fit together. The engineer came down and saw the assembly for the first time in 3D and said when looking at it, "well it worked in CAD." Remember to honor our Veterans today.
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