Hi Ted,
As a "neophyte" when it comes to stunt ship design (I just build others planes!0 I have become aware, however, of the vertical CG effect on our planes.
When looking at the pic of the real Talon, I see a lot of mass above the wing AND stab. On a low wing plane we get "rolling" iin the manuevers if the V-CG gets too high, what about the stab? What effects would show up?
Thanks,
Bill <><
It's really pretty simple, Bill. Let me use one of my favorite techniques ... envisioning the effect in the extreme.
Let's assume a more or less standard 60" span stunter with a very high T-tail six inches above the thrustline.
You're flying along straight and level and while passing under a "limbo stick" (bear with me here, we're talking theoretical examples) you're just a touch too high and the tall stab hits the stick. What's going to happen (assuming everything stays in one piece)?
Clearly, hitting that stick is a big "drag" on the direction of flight and the ship is going to pitch up in response to that drag well above it's CG.
While this example is extreme it is important to remember that "any" amount of drag at that raised location is going to try to pitch the airplane nose up commensurate with the amount of drag and the deviation of that drag from the "aerodynamic centerline" of the airplane.
In level flight you would simply trim it out with some downthrust and/or a little down elevator or even build in a little extra negative incidence.
Where it might prove to be a problem will be when maneuvering. As the tail produces the lift required to change the attitude of the ship it will also be producing a lot more drag (induced drag from the production of the required lift) than when in level flight. (Granted, in some proportion to the overall induced drag increase from the wing). That increased drag at the tail's location will act sort of like hitting the limbo stick. It is going to accelerate inside maneuvers but will resist outsides. It is likely going to result in uneven inside versus outside response rates. The difference may or may not be something that can effectively be trimmed out.
Ted