by M Lightsey » Wed Jan 19, 2011 2:23 pm
There's no more friction in the cable assembly than the pushrod assembly.
There are 3 cables in the system, each with 2 forks and clevis pins. That's 6 points of attach or contact. There are also some fairleads, but if built and rigged properly, the cable doesn't rub the fairleads. The cables are all straight shots, there aren't any pulleys or changes of direction of any kind.
The pushrod setup has 4 pushrods, each with a rod end (expensive) plus the idler assembly with it's bearing or bushing. That's a total of at 8 points of contact plus the idler.
I don't see the advantage of the pushrod system. More complex, heavier, more expensive.
If you're getting into very large or very fast airplanes, there are other considerations like temperature and cable stretch, but those things are not an issue for the Hatz.
A lot of guys will rig control cables so tight that they're like banjo strings and that can cause resistance in a system, but that's a rigging problem not a design problem.
Any heaviness in the Hatz ailerons has more to do with the design of the ailerons themselves than the system used to actuate them. There are 4 realtively large, unbalanced and unboosted slabs hanging on piano hinges, and it works perfectly for 1930's style biplane flying at less than 100 mph. It's not a Pitts, but then again neither is a Waco or TravelAir.
Just my $0.02
Mark
There's no more friction in the cable assembly than the pushrod assembly.
There are 3 cables in the system, each with 2 forks and clevis pins. That's 6 points of attach or contact. There are also some fairleads, but if built and rigged properly, the cable doesn't rub the fairleads. The cables are all straight shots, there aren't any pulleys or changes of direction of any kind.
The pushrod setup has 4 pushrods, each with a rod end (expensive) plus the idler assembly with it's bearing or bushing. That's a total of at 8 points of contact plus the idler.
I don't see the advantage of the pushrod system. More complex, heavier, more expensive.
If you're getting into very large or very fast airplanes, there are other considerations like temperature and cable stretch, but those things are not an issue for the Hatz.
A lot of guys will rig control cables so tight that they're like banjo strings and that can cause resistance in a system, but that's a rigging problem not a design problem.
Any heaviness in the Hatz ailerons has more to do with the design of the ailerons themselves than the system used to actuate them. There are 4 realtively large, unbalanced and unboosted slabs hanging on piano hinges, and it works perfectly for 1930's style biplane flying at less than 100 mph. It's not a Pitts, but then again neither is a Waco or TravelAir.
Just my $0.02
Mark