Earthstar Forums

I like the idea of a a T tail because it mounts up high where it is less prone to damage,it could be much smaller as evidenced by Pipistrel and most glider manufacturers, should have less drag ( smaller size ) plus a carbon fiber boom 18" plus longer would place it further back for mechanical advantage in handling and slightly less buffecting from the prop .I know a "V" tail has been tried with mixed reults.Now time for a "T" Gull.The advantages of less drag would also translate into higher speeds ,lower fuel burn with the same hp.
Just my thouhts
Carl

Hi Carl
The resens why I don't use a t tail are that the current position is influenced by the flaps that cancels out the strong nose down pitching moment of large flaps. A t tail will not do that causing a need to re trim for flap extension. The current position allows the pilot to come to the pattern at cruse trim and put the flaps down with the flow pattern over the tail neutralizing the nose down pitching moment and causing a slight nose up pitching that changes the trim speed to be the pattern speed instead of cruse speed.
T tails can end up in the stall flow field behind the wing reducing its effectiveness and making the configuration harder to recover from a spin.
Our Stabilator rides in clean air. And is set back far enough to keep most of the vertical out of its stall field.
At least these are some of the resins for my disision to use a low mounted tail. O ya and it is easy to mount on the end of the tail boom with simple cable routing and is also lighter for these reasons.
Happy Designing
Mark
Sent from my iPhone

I agree with Mark B, and also want to add that EVERY design is a trade-off. That is why so many brilliant minds have created as many designs.



Another T-tail issue that Mark did not mention is that if you move all of that weight to the top of the vertical stab, you now have to a lot of reinforcing on the vertical stab for 2 reasons: Structurally, it applies its loads out at a distance (i.e. the height of the vertical), and secondly, stiffness comes in to play. The mass of the T tail makes the flutter speed of the vertical/horizontal system go way down. That means it will vibrate at a lower frequency, and move a lot when it does. Also you will now need more nose weight to counter balance the added structural weight of the vertical stab.



Again… T-tails aren’t intrinsically good or bad, but it is all a trade.

Great discussion. Real pilot, real airplane discussions like this are really educative. Helps me to understand the aircraft better and better. Thanks to all for this thread. RMM
Earthstar Odyssey
HKS 700E

There you go. it all makes sense to me now. Keep it simple and light. I’m totally satisfied with our pitch stability, and would not see a reason to change it. Talk to a Skipper or Tomahawk pilot and they will mention the lack of elevator authority at slow speed. Mark’s design works really well, and even the copy-cats didn’t change it.

I totally agree with Mark's reasons. 
T-tails look cool, but they're difficult to implement mechanically and aerodynamicly.
About the only thing I could wish for would be a retractable pod leg (or something) on the boom tube that would keep the stabilator off the ground when parked. My Odyssey would sit on the nose wheel when parked, but just barely. It's awfully easy for someone to step on it when it would be down on the ground. 
... just my buck ninety eight.

A trick Mark showed me is that when the tail wheel is on the ground with any of our planes, just use the seat belt to pull the the stick all the way back, and the stabilator is out of easy stepping reach. Just my .002.
kb

Gee! I think I saw a cockpit activated rear gear leg for a JT2 some where... let me see...awe I forget....
Fred

Or when I fly out, sometimes I take my 3-legged stool that folds up and stows easily and slips right under the boom when parked.

I got one too! camel leather low seat, very useful for debugging sessions. how much does you're 3legged stool weigh?

Was just wishing the seat was one of those anti ballistic steels yesterday. kinda like when Marty Mcfly dueled with maddog tannon in BTTF3, with a furnace lid slung across his chest.