Conventional vs. T Tail, pros, cons?

kontiki

kontiki

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Kontiki
All, been looking at Piper Arrows, I see the Arrow IVs have a T tail.

Performance wise, what did that get them?
 
What you get is the horizontal stab up out of the prop wash, which reduces inflight vibration -- the reason, I believe, which Piper did it. The other thing you get is the horizontal stab up more out of ground effect, which significantly changes pitch response on takeoff and during the landing flare and touchdown. There are also some changes in pitch feel during slow flight and stalls. All in all, it handles a bit differently in those situations, but most folks get used to the difference pretty quickly. What most of us also get is the need to have a ladder to preflight the tail.
 
It got them more weight and less authority in the TO roll and flare....
 
Really fun when you've got frost on the aircraft you need to get off. On the DA-40, we could have one person pull the tail down while the other cleaned it. Not sure if that can be done with the Arrow.
 
And the reason we used black paint on the top of G-V tails.
 
I've never met a T-tail that I thought was attractive.
 
I like the DA40, but do not find T-Tails attractive.
 
I've always liked the B-200.
 
On light airplanes, the primary reason that T-tails were used was aesthetics.
 
I really don't care either way except to be ready for the different feel on takeoff and the flare. On takeoff the nose can "pop" up in a different manner than a more conventional tail. And on the landing roll the tail can seem to lose authority all at once with the nose coming down.

So I make it a point to "fly" the nose more deliberately with t-tail airplanes.
 
A local lawyer decided to buy a T-Tail Lance with the intention of combining instruction into frequent x/c trips with the assumption that obtaining a PPL would be relatively simple. He was wrong. Poor sumbitch has struggled with every imaginable problem and still doesn't have it done.

TMetzinger said:
I really don't care either way except to be ready for the different feel on takeoff and the flare. On takeoff the nose can "pop" up in a different manner than a more conventional tail. And on the landing roll the tail can seem to lose authority all at once with the nose coming down.

So I make it a point to "fly" the nose more deliberately with t-tail airplanes.
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I haven't flown an Arrow with a T-tail, but have flown both T-tail and straight tail PA32s. Only advantage of the T-tail is that it is typically cheaper to purchase.

That should tell ya somethin'
 
I used to do checkouts in 3 PA32RT-300's and Commercial
Instruction in a Arrow IV. Soft Field takeoff, not going to happen.
Airplanes that need yaw dampners in turbulence, these are the
ones. Heavy empty weight and slow, same ones.
There's some really good reason's they are cheaper.
All opinion.
Dave
 
DouglasBader said:
On light airplanes, the primary reason that T-tails were used was aesthetics.
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T-tails were the marketing fad of the 1970s. DC-9s and King Airs had them, and Cherokees should too, so the reasoning went. Interesting that Cessna test-flew a T-tail prototype Model 187 (a Cardinal-like design intended to replace the C-182, and IMHO hideously ugly with the T-tail), and Beech tried a T-tail stretched 36 Bonanza (sacrilege!), and neither went to production. After a few years even Piper reversed itself and went back to low tails on the PA-28R and PA-32R models.

Ron Levy said:
What you get is the horizontal stab up out of the prop wash, which reduces inflight vibration -- the reason, I believe, which Piper did it.
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Piper also claimed -- correctly -- that the T-tail reduced trim changes with landing gear and flap operation.

But taking the stabilizer out of the energized propwash reduces pitch authority on the takeoff roll. That, coupled with the fact that the PA-28RT stabilator is 13% smaller in span and area compared to that of the low-tail Arrow III (probably for structural reasons), means that a PA-28RT needs about 75 KIAS on takeoff before it feels like it's ready to rotate.

People complain about a Bonanza's yaw oscillation in turbulence. I think a PA-28RT is at least as bad in that regard.

The fillets, slots and fences on the PA-28RT stabilator suggest to me that Piper engineers had a difficult time making the T-tail fly right.
 
timwinters said:
I've never met a T-tail that I thought was attractive.
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How about this one:

640px-Schleicher_ASW27b.jpg


I'd buy one if I won the lottery.
 
I've flown both T tailed and straight tailed Arrows. I prefer straight tailed Arrows. But I really like the way the DA40 flys.
 
I agree. So far the DA40 is the only T-Tail that I really like to fly.

That's not saying I didn't like the Arrows and the Turbo Lances I've flown with T-Tail. I haven't flown a "bad" airplane yet.
 
wabower said:
I've always liked the B-200.
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Nahh...the 90 and 100 were pretty good lookin' birds. The 200 and 300 not so much.

But admittedly it's a "beauty is in the eye of the beerholder" topic!

;)
 
Capt. Geoffrey Thorpe said:
Marketing.
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That's probably what led Cessna to change the 172 and 182 to the swept vertical stabilizer in the early '60s, I'd guess. A fastback 172 or 182 with a swept VS is kind of awkward looking, IMO. But they sell for not much money and can be a good deal. The Commander singles with the cruciform tails didn't set the world on fire sales-wise, either. If shape was all it took to sell airplanes, the C177 would have been a lot more successful, I'd think.
 
bbchien said:
It got them more weight and less authority in the TO roll and flare....
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But when you got authority, you got it RIGHT NOW.

With the elevator in the slipstream, you got some elevator authority from the prop blast. With the T-tail, you didn't. So when you began your takeoff roll with the elevator "full up", the elevator was stalled.

And at some speed it unstalled, taking you from very little downforce on the tail to a whole lot, virtually instantly. That caused more than a few tail strikes.

It worked the other way too. You'd be rolling out with the nosewheel off the ground and at some speed, elevator authority would just fall off a cliff.
 
Aside from the aforementioned lack of propwash, because a T-tail is usually further aft and has more lever arm, it can be made smaller, with less overall drag. Not a bad concept, but the aircraft I've flown with both type of tail, I prefer the straight tail.
 
The Cessna 303 was not truly a T tail, but it was close enough that I didn't really care for it.
 
The only difference I notice is a bit less elevator authority at low speed, all in all, no big deal except for "soft field" work.
 
For a beholder who's also in charge of loading, one of the beauties is that you can't get one out of the envelope.
timwinters said:
Nahh...the 90 and 100 were pretty good lookin' birds. The 200 and 300 not so much.

But admittedly it's a "beauty is in the eye of the beerholder" topic!

;)
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j1b3h0 said:
Aside from the aforementioned lack of propwash, because a T-tail is usually further aft and has more lever arm, it can be made smaller, with less overall drag.
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And it weighs more, because the vertical stab has its original task (yaw stability and control) as well as now having to take the horizontal stab's pitch loads, and the torque loads that a horizontal stab can also generate due to spiralling propwash, turbulence, and so on.

As others have said, it was a fad. Like the "ram-air" hood scoops on muscle cars of the '70s, tailfins of the late '50s and early '60s, spoilers on the back ends of many cars not too long ago. Whatever convinces the buyer to spring for it.

Some T-tailed airliners, seems to me, had deep-stall issues. The tail would get blanketed by the wing's wash at high AoAs and prevent stall recovery. How's that for being in style?

Dan
 
Skylane81E said:
I like the DA20,
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The DA20 is a nice plane, but that skinny tail boom just plain wrecks the aesthetics. Yeah, I know the part aft of the wing's center of lift multiplied by the arm of the tail is good enough to make it fly, but for Pete's sake...
But the only other T I've flown is a Skipper.
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And about 20 years ago there was a PBS TV flight training series that featured a Skipper. It was a pretty good show. Wonder what happened to the CFI, the students, and for that matter, the Skippers....
 
I agree with Wayne that the King Air 200 is an attractive airplane. So is the Lear 35. Both of them have a soft spot with me.
 
kyleb said:
But when you got authority, you got it RIGHT NOW.

With the elevator in the slipstream, you got some elevator authority from the prop blast. With the T-tail, you didn't. So when you began your takeoff roll with the elevator "full up", the elevator was stalled.

And at some speed it unstalled, taking you from very little downforce on the tail to a whole lot, virtually instantly. That caused more than a few tail strikes.
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I'm trying to figure out how the tail could be stalled and then magically unstalled when its angle of attack never changed? :dunno: (Let's assume for this thought exercise that the pilot simply held the yoke in the full aft position.)

Authority change, most definitely - I'm not a fan of the T-Tailed Pipers, though the DA40 doesn't seem to have the bad habits that the Pipers do. But I don't think it's a tail-stalled-to-unstalled issue on takeoff, because the tail has to have some authority before its AoA can change.
 
The only T tail I've flown... And the lesson was great fun.
 

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The most important reason why T-tails are used on gliders is that its interference drag is measurably reduced when compared with any other tail arrangement. It is also the reason why Pantera went with it.

Arrow, unfortunately, was a poor implementation of the concept. If much of anything sticks above the tail, it loses the advantage. Also, the lack of propwash and reduced area were really ill-advised in that airplane in consideration of takeoffs and landings. Everyone who flew both kinds vastly preferred the standard tail version.
 
Other reasons for t-tails in gliders are associated with landing out in unimproved fields and less potential for damage while ground handling. Landing on a farmers field the t-tail will be up and out of the way and not snagging plants and such. A glider with a conventional tail will have the horizontal stab very close to the ground. In this case it would be a lot easier for people to inadvertantly run into it and cause damage.
 
I have about 200 hours in a T tail Lance and do some instructing in it.

The stabilator is out of the prop wash on the take off roll.

For the hamfisted flyers who feel the need to call out their rotate speed and jerk back on the yoke forcing the airplane off the groud - this airplane is a great tool to teach them to chill out and start performing good take offs.

As soon as you do an agressive rotate - the stabilator drops into the prop wash and goes from barely effective to very effective - the nose instantly shoots up and you better be ready to shove forward on the yoke till the hamfisted pilot gets a better grasp on it.

Its realy not a big deal if you understand the airplane and fly accordingly.

In flight - hard to tell a differance.

Stabalized approaches and landing - no real differance.

Big changes in power settings during approach and landing - can also get interesting.
 
Benchracer52 said:
I have about 200 hours in a T tail Lance and do some instructing in it.

The stabilator is out of the prop wash on the take off roll.

For the hamfisted flyers who feel the need to call out their rotate speed and jerk back on the yoke forcing the airplane off the groud - this airplane is a great tool to teach them to chill out and start performing good take offs.

As soon as you do an agressive rotate - the stabilator drops into the prop wash and goes from barely effective to very effective - the nose instantly shoots up and you better be ready to shove forward on the yoke till the hamfisted pilot gets a better grasp on it.

Its realy not a big deal if you understand the airplane and fly accordingly.

In flight - hard to tell a differance.

Stabalized approaches and landing - no real differance.

Big changes in power settings during approach and landing - can also get interesting.
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Awesome explanation. I took at face value everyone's word that the Tomahawk had a tendency to pitch up aggressively on takeoff. Now the reason for that makes sense. Thanks. :)
 
kyleb said:
But when you got authority, you got it RIGHT NOW.

With the elevator in the slipstream, you got some elevator authority from the prop blast. With the T-tail, you didn't. So when you began your takeoff roll with the elevator "full up", the elevator was stalled.

And at some speed it unstalled, taking you from very little downforce on the tail to a whole lot, virtually instantly. That caused more than a few tail strikes.

It worked the other way too. You'd be rolling out with the nosewheel off the ground and at some speed, elevator authority would just fall off a cliff.
Click to expand...

I've had my DA20 for 8 years/1300 hours and never had a tail strike or sudden nose drop. But I have to admit that a conventional tail is much better for short or soft fields.

But dammit, IT JUST LOOKS COOL. :) :D
 
I have flown a T Tail lance a bit... It isn't that big of a deal, as long as you don't aggresively rotate, and watch the nose on landing... In other words, just remember what plane you are flying..
 
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