Airfoils on Do X

I am building the old Revell 1:144 Dornier X. I find there are little aero surfaces above the hinges on the elevators and ailerons. They are slightly forward of the hinge line, so it looks like they could apply torque to the control surfaces.

Are these trim tabs, or possibly servo tabs? They look far to big to be trim tabs, in my estimation, especially the aileron tabs. Might they be servo tabs to alleviate possibly very high control forces on such a huge aircraft, without requiring a complicated hydraulic system?

I built a model of the USS Akron a few years ago, and noticed the same tabs in that aircraft. Did any other aircraft other than the Graf and the Do X have such features?

Don I would think with large controll surfases they are booster tabs to lighten the controlls.

Theuns

Don I agree with Theuns,

There are several early AC that used that method. The Fiat Cr32 comes to mind.

Even small planes like the Pitts S2’s I work on have them to lighten the collomb. The tabs work like boosters but also double trim tabs with a lever in the rear cockpit left side.

You can see the controll links between the tab and the aileron on that cr 32

Theuns

Don - My guess is that since the tabs are located at the hinge point and would likely have no mechanical leverage effect for lightening control forces, maybe they deflect the airstream to induce control surface movement???

Only thing I can think of, but only my guess. Interesting subject, I hope we get an official answer.

Patrick

Don :

They are there to lighten the response to the controls . T.B.

I believe that even if the tabs sit inline with the hindge point but above or below it , it would still have a pivot moment affecting the surface.

Theuns

I also received some input from another forum I frequent, on aviation history. The consensus of both groups seems to be servo tabs. Looks like they were indeed servo tabs, just a different positioning and arrangement from the servo tabs we now put on the trailing edge of control surfaces. Sort of a combining of current servo tabs and aerodynamic control system balance, which is sort of a passive way of reducing control forces.

That would seem to be the right explanation.

I made a sequence error when I built that kit. It’s probably worth rigging all of the little braces for the engine pods, but it’s finicky work. I glued all of the pods on first, but that made it impossible to get in there and add the braces. I think it would have been better to go one-at-a-time, if one was so inclined.

According to Scalemates, the kit was originally an Otaki kit, then Yodel (?), then Revell, then Matchbox which was the one I had, then two more issues of Revell.

Thanks! I am not ready for the engines yet, but I had intended to do it the way you did. Thanks for the warning. I’ll mount them seperately, each brace with the engine.