Sky Ray elevator travel

[Bootlegger]

  Guy's what will be a good amount of elevator travel that will let the model fly and stunt with out stalling. It will be powered with an L A 25-- Veco 35, and used to help train for stunt flying..

  As usual thanks a lot...

[Steve Helmick]

It's going to depend on how close to the glowplug the CG is, just like any other design.  Steve

[Brett Buck]

  Guy's what will be a good amount of elevator travel that will let the model fly and stunt with out stalling. It will be powered with an L A 25-- Veco 35, and used to help train for stunt flying..

  As usual thanks a lot...

   I don't think I understand, a Veco 35 and 25LA are about as far apart as they get in terms of performance. But for the most part, you probably want *a lot* of travel for the 25LA, +-45 with full hand movement. That's because tail moment is pretty long. 


     I will have to get back to you later on how to refine it, or read the numerous posts - you want as much travel as you can get without stalling the wing.

[Peter in Fairfax, VA]

> want *a lot* of travel because tail moment is pretty long

Hmm.  I thought the throw requirement decreased when tail moment increased.

[Serge_Krauss]

The longer the tail, the more positive/negartive its angle of attack becomes in inside/outside maneuvers. This effect becomes greater with decreasing turn radius. Frank Zaic called this "circular air flow." Here's an exaggerated diagram of a stunt plane in an impossibly tight-radiused turn to illustrate the effect. So while the moment arm becomes greater, giving greater leverage as the fuselage lengthens, the aerodynamic forces from elevator deflection decrease. You could recover much of this - within reason - using an all-flying horizontal tail ('stabilator').

SK

[Bootlegger]

  The model is already set up with an O S L A 25, and I have gotten a Veco 35 that I plan to install on the model to see how the Veco will work on the model as it is a single by-pass engine, and runs differently, the model will be used to help train a new flier on how to fly stunt..  Hope that this is more clear

[Brett Buck]

  The model is already set up with an O S L A 25, and I have gotten a Veco 35 that I plan to install on the model to see how the Veco will work on the model as it is a single by-pass engine, and runs differently, the model will be used to help train a new flier on how to fly stunt..  Hope that this is more clear

     Do you get the part about the tail moment and elevator deflection? Short tails permit high rotational rates, which can drive the wing into a stall easier. Longer tails give you more "torque" when the pitch rate is low, but it falls off faster at the pitch rate climbs, an in the case of the Skyray, it is relatively easy to achieve the full pitch rate, and thus not get all the lift out of the wing you might otherwise get- and make the corner radius excessive.

     The stock "plywood" wing version of the Skyray 35 will probably tolerate at least +-45 degrees of deflection. A balsa-wing version will tolerate/require *much more* deflection to maximize the performance

   It will fly much better with the 25LA, if you run it as suggested. This is particularly true using it for a stunt trainer.

      Brett