Standard tail feather to-----> T tail

[Buzz Bomb]

Just wondering if there are any concerns I should take into account if I convert my SPADs standard tail feather configuration to a T tail configuration. I don't have a lot of experience with T tails and any information would be appreciated.

Thanks :)

[JetPlaneFlyer]

Aerodynamically it should work fine. A high set 'T' tail should operate more efficiently because it's out of the wing's wake, so it could possibly be reduced in size a little... but leaving it at its original size will do no harm.

Structurally, in a heavy landing, a T tail puts a lot of stress on the fin to fuselage joint and also on the fuselage itself just forward of the fin. A few times I've seen 'T' tail fuselages snap in this area , so some 'beefing up' may be in order.

[Buzz Bomb]

Thanks.

Does anyone else have any input?

[Ollie]

Consider the more complex elevator control linkage.

The T-tail mass inertial load has two kinds, twisting (landing loop) and bending (in-nose landing).

[yoyoML]

Don't pull to stall with a T-tail. The tail may be right under main wing wake when the main wing stalls, making it difficult to recover.

[BMatthews]

Don't pull to stall with a T-tail. The tail may be right under main wing wake when the main wing stalls, making it difficult to recover.

The old F104 was supposed to suffer from that issue but I've never had or seen anyone else have any problem with models. So I'd have to say that this isn't really something to worry about. And I've had 4 or 5 T tail'ers myself.

I'll also echo the need for a STRONG fuselage and vertical fin. I'm one of the folks that managed to snap the fuselage just as said on one model.

But you can minimize the extra strength needed by REALLY lightening the stabilizer and keeping the fin light as practical. Also making the fin with a thicker 10'ish% airfoil will provide a lot of the needed strength and stiffness. But keep the stab LIGHT! Even if this means foregoing the corroplast in favor of a built up balsa and film covered option.

[Padesatka]

To me, T-tails have too many trade-offs: They require heavier structure for equivalent durability, because the vertical stabilizer must support greater torsional loads, and any asymmetric loading is concentrated in a much narrower mounting area, unless you add flying wires or struts. Because a conventional tail is in the propwash, it enjoys greater (not lesser) control authority for equivalent elevator area (IMO). Another issue is the less direct pushrod control runs with a T-tail. There is a slight lower-drag advantage to T-tails, but it comes at a price in structural weight.

The best comparison I've experienced between the two has been in the full-scale world, flying Piper Arrows and Lances of both varieties. They are equivalent airplanes except for the high/low tail variations. The low-tail versions handle and perform noticeably better, especially at low speed. T-tailed Pipers sell for about 20% less for this reason, and the T-tailed versions were discontinued first in production, even though they were a 1970s "advance" (I think it was a fad).

There is sometimes talk of "deep" stalls, where the horizontal tail is in the wake of the stalled wing root, but I've never experienced such a thing while flying (and stalling) Super Blaniks, Katanas, Tomahawks, Duchesses, T-Arrows, and T-Lances. In the Piper Tomahawk, it is a little bit disturbing to look back at the tail in a spin, because the entire empennage visibly oscillates torsionally (It never bothers me so long as I remember not to look).