I've got a old Magnum wing, for those of you who don;t know this ARTF speed ship its, swept, very thin, very sharp LE, and amazingly light too.
The wing was snapped in half just before a crash and I've fixed it, the rest of the plane went a bit quicker than 200 after it lost all this drag

I have a couple of old separate tail plane half's from an old speedster which i just held in place behind the wing in a V.

Question is I'm unsure if I want a V-fin on a very short fuz and have a delta set-up, or have a standard length fuz and working V-tail for standard set-up.

Are there any problems with having what is still essentially a V-tail on the Delta thats trying to out do any elevator input. and do I use Delta CofG?
Or should I forget this and have a standard plane.
I want something different because I have my own fully grown Magnum on the way and don't need two, plus my only spare engine is a 21 and I think the full fuz idea would warrant a quick 36 at least.
I even thought about putting a pattern style fuz on for a fast plane that will KE too... I'm crazy.

Hi phillybaby
I am putting a plane together like your description. I am way too nose heavy with my cofG calculated at 25%. What cofG % is recommended on the magnum?
Thanks
Todd

to be honest you fit the gear and throw it. but i THINK it's 125mm measured from the root's front edge. i'll find out for sure... ah there you go, theres a line at 135 in my fuz, you move it back slightly for better elevator movement from Westons 125mm.... BUT! if your making a delta move this forwards by 8% of the roots chord

PhillyBaby - While I can't prove this because I can't build an infinite number of airplanes, I am convinced that any plane can fly with any size tail surfaces as long as the cg is right. As the tail moment gets shorter, the cg becomes more critical. I've built some really bizarre models that flew fine once the CG was dialed in. It's just a lever with some aerodynamics added.

point is, they might not be tail surfaces, they might just be a fixed vtail a few inches from the back of the delta wing. i've still got the wing and might get back on to the idea one day, far to many other things on my board right now

CafeenMan - well almost. There is a controlability issue involved as well as necessity for static and dynamic stability. Big tail surfaces on a long fuselage allow the CG to be moved aft for a given stability margin and certainly have adequate control. Keeping the horizontal tail at the same fuselage length location, as you resize the tail to be smaller, the CG must move forward to balance the aerodynamics and the smaller elevators start to lose their control power. It continues until the tail area is zero, with no control and the CG is moved ahead of the 25% of the remaining wing, however long before that there be a point that for all practical purposes there is not enough stabilizer/elevator power to control the airplane.

Going the other way, with a fixed size horizontal and a decreasing fuselage length, the control reduces and the CG must move forward as the fuselage goes to zero. However with the tail at the trailing edge of the wing there is still some control and stability left.

Hi Phillybaby

Finished my Vtail. Not as short coupled as you where thinking. Flys nice and straight.
She really slows down after I cut the engine, and hold the elevator on landing. Tail just drags in the snow, then noise touches down.
Very stable on landing and take-off. Still need cowl. Weighs 3 1/4lbs.

I balanced the wing at approximately 18% of MAC for first flights. I think I can go up to 15%. I'll put my pipe on soon to get this thing humming.

P.S. This is a winter plan so I only put a OS 46FX on it. Engine needs to be reliable in our -15C weather these days.

thats the kinda thing i want to do, only my V tail wouldn't move

Oh, I guess your plan was to use elevons. I think this would work. Something like a Diamond Dust tail, except it is extended off the back.

Murrat, you got my attention when you said you had the CG at 18% mac. That CG is so far forward as to make the airplane almost unflyable. You would have to hold a bunch of up elevator and they don't look all that big. Are you sure that it is 18% of mac and that you have the mac figured OK.