changing to push rods for ailerons

[gaylonhpugh]

I've got wings already covered but not rib stitched and a fuselage cover that I already know has to come off to reset the seat,etc. What I'd like some feelings on is whether I'd be much happier taking the wing covers off and fabricating push/pull rods for the ailerons instead of leaving the cables already installed? Is the operating difference that great? I'm sure there is a difference; it seems everybody's going to the rods.
Gaylon

[mtaylor]

As always, it's personal preference as I see it. Yes the stick drag is much less with push rods, but IMHO, the old biplanes of the 30's weren't cadillacs anyhow. If I were to be flying this biplane on a daily basis, many hours per day, it'd be worth all the extra time and work to redo the thing with pushrods. My RV4...definately pushrods, A 1930's era biplane...nah.

Just my opinion, fwiw.

[Jackal]

What would your opinion be on a plane with the lower wings not built yet? Nothing to re-do, so the choice is wide open. I do agree that the style would be more 1930's with the cables, but do the rods improve aileron control feel that much??

[dougm]

Not all 1930's vintage biplanes were cable-actuated (though many were). The Waco QCF/UBF, for example, had push rods. I'm sure others did as well.

[mtaylor]

Control friction is reduced a good amount with push rods. Myself, I wouldn't tear off good fabric to change things. But building the wings for push rods is, again, builder preference. One thing I've learned over the years is that if you think you aren't happy with a particular aspect of your build, you'd best change it now instead of spending the rest of your years flying the airplane and wishing you'd made the change when you had the chance. Clear as mud? Make your Hatz the way YOU want it. I've never seen a Hatz that wasn't a beauty in it's own right. A builder's pride and joy.

[gaylonhpugh]

OK ...here's the deal....if I were going to build a classic like a '55 chevy.....I'd want the look I was after to be ....the '55 (with a non 50's paint job, a good set of new mags)....and I'd want everything under the hood and in the chassis to be new...up-to-date tech.I don't want to open the hood and show everyone it's just like they did it 55 yrs ago.

I plan to fly this plane a lot...crosscountry. I really need to see if the difference in control friction would matter to me ....would justify the time spent rebuilding not flying. I've flown an RV a couple of times ...both were really smooth, almost frictionless.

Thanks for all the good words.....I'm gonna have to physically visit with some Hatzer's and feel their planes I think before I'll know what to do. Just moving the stick will do it I think. Oshkosh this summer?

The phrase "control friction is reduced a good amount with push rods" really bothers me......if the choice were "wide open with no fabric on"?.....no question ....I'd install the pushrods

gaylon

[dougm]

I'm gonna have to physically visit with some Hatzer's and feel their planes I think before I'll know what to do. Just moving the stick will do it I think. Oshkosh this summer?

If you don't have any "local" Hatz's to visit, I would recommend going to Brodhead (right before OSH). Lot's of Hatz folks to talk to and rides to be had.

[M Lightsey]

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

[gaylonhpugh]

excellent food for thought all....just what I needed. Points and counterpoints..it all comes down to weighing what your individual pros and cons are. Doesn't sound like one is vastly superior to the other.

I thought about Brodhead Doug but its probably going to be one or the other due to work. There will be some Hatz at Oshkosh won't there?

[mtaylor]

Mark, excellent points. I built an RV4 and flew it for 4 years. The difference in control friction between the RV and my yet unfinished Hatz is pretty substantial (I've traced it to my torque tube). My Hatz (CB1) torque tube is a tube sliding inside two clam shells with grease to reduce friction. The RV is ball bearing. My Hatz uses piano hinge on the ailerons. The RV...again, ball bearing.That seems to be where the difference in friction happens. The only bearings on my Hatz are in the aileron bellcrank. Whether you push/pull with one stiff pole, or pull/pull with two cables, the drag producers are in the actuation of the torque tube, bellcrank and aileron hinge.

You made me think. Good post