Why do smaller jets always seem to utilize the T tail design?

CC268

CC268

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CC268
Just wondering why the smaller business jets and even some of the midsize jets seem to usually have a T tail over a traditional tail design. Why is this? I am thinking maybe because of the engine placement?

Are the flying characteristics much different from a traditional tail design? Stall characteristics etc?

Thanks
 
Engine placement could be part of it, but I believe it boiled down to being able to reduce the size (hence reduced weight and drag) of the horz. stab and elevator by moving it up into "cleaner" air.
 
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The T-Tail tailplane is kept from the disturbed airflow behind the wing and fuselage, giving smoother and faster airflow over the elevators. The config gives better pitch control for jets. Responsive pitch control is crucial for aircraft flying at low speed, to allow more effective rotation on landing.

A T-tail has a better effective aspect ratio, less interaction drag, and a more efficient vertical tail. Therefore, the T-tail configuration is especially popular on gliders too.
 
The t-tail is in of the ugliest airplane designs ever imo. My opinion may change but I for now I can't stand it.
 
Almost all of the large biz jets have T-tails too. Only a few have conventional tails.
 
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citizen5000 said:
The T-Tail tailplane is kept from the disturbed airflow behind the wing and fuselage, giving smoother and faster airflow over the elevators. The config gives better pitch control for jets. Responsive pitch control is crucial for aircraft flying at low speed, to allow more effective rotation on landing.

A T-tail has a better effective aspect ratio, less interaction drag, and a more efficient vertical tail. Therefore, the T-tail configuration is especially popular on gliders too.
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Yea I remember discussing those reasons in my aero systems dynamics class...but why don't they use it on the big jets if it is a better design overall?
 
Can anyone think of a t-tail jet with wing engines?

How about one with a conventional tail with fuselage mounted engines ?
 
SkyDog58 said:
Can anyone think of a t-tail jet with wing engines?

How about one with a conventional tail with fuselage mounted engines ?
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C-141 and C-5, for starters.

Pretty much any 4-engine jet has to have them on the wings.

DC-10s have tail mounted engines and conventional tails, but I don't think that's quite what you meant.

The Dornier Alphajet has body mounted engines and a conventional tail, but they are also under the wings.
 
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SkyDog58 said:
Can anyone think of a t-tail jet with wing engines?
How about one with a conventional tail with fuselage mounted engines ?
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There are some disadvantages:
Dangerous deep stall, where a stalled wing at high angles of attack may blank the airflow over the tailplane and elevators leading to loss of pitch control.
The vertical stabilizer must be made considerably stronger, stiffer and heavier hurting fuel efficiency.
The T-tail configuration can cause maintenance concerns.

The military like the T Tail likely due to cargo loading advantages from the rear.
And three engine commercial planes use them to make room for the tail mounted third engine.
 
citizen5000 said:
There are some disadvantages:
Dangerous deep stall, where a stalled wing at high angles of attack may blank the airflow over the tailplane and elevators leading to loss of pitch control.
The vertical stabilizer must be made considerably stronger, stiffer and heavier hurting fuel efficiency.
The T-tail configuration can cause maintenance concerns.

The military like the T Tail likely due to cargo loading advantages from the rear.
And three engine commercial planes use them to make room for the tail mounted third engine.
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I was expecting someone to answer with C-141, C-5, etc. and of course the reason is tail loading of cargo. The t-tail is most often a design choice of accommodation of other design factors rather than aerodynamics.
 
SkyDog58 said:
I was expecting someone to answer with C-141, C-5, etc. and of course the reason is tail loading of cargo. The t-tail is most often a design choice of accommodation of other design factors rather than aerodynamics.
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Then, the obvious next question is, why do some Arrows have T-tails and most don't?

Why do small turboprops like Beech's and Pilatus' have T-tails?
 
MAKG1 said:
Then, the obvious next question is, why do some Arrows have T-tails and most don't?
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... and Tomahawk, Seminole, Skipper, Duchess, etc., etc. Marketing. All the cool kids had T-tails in the late '70s.

It's telling that both the PA-28R and PA-32R series had T-tails for a while, then reverted to the original low tails. Even Cessna got into the act. They flew a proposed Cardinal-like 182 replacement, the Model 187, with a T-tail. Ugggg-ly.

Looking at all the aerodynamic gimmicks on the PA-28RT stabilator (fences, fillets, leading-edge slots), it seems Piper engineers must have had a heckuva time getting the thing to fly right.
 
CC268 said:
Just wondering why the smaller business jets and even some of the midsize jets seem to usually have a T tail over a traditional tail design. Why is this?
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Because they are too short to have under-wing engines.
 
SkyDog58 said:
Can anyone think of a t-tail jet with wing engines?

How about one with a conventional tail with fuselage mounted engines ?
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The Sabreliner has a conventional horizontal tail with fuselage mounted engines.
 
I think one of the main points, as has been discussed, is the jet blast over the tail.

I think the designs speak for themselves. I'm certain the exceptions have been looked at closely by the engineers.

Truly nothing to see here.
 
They all seem to work huh. Maybe the pilots working these planes has figured these things out.
 
Pilawt said:
... and Tomahawk, Seminole, Skipper, Duchess, etc., etc. Marketing. All the cool kids had T-tails in the late '70s.

It's telling that both the PA-28R and PA-32R series had T-tails for a while, then reverted to the original low tails. Even Cessna got into the act. They flew a proposed Cardinal-like 182 replacement, the Model 187, with a T-tail. Ugggg-ly.
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And then after the 70's T-tails got a bad name, which makes me wonder how Diamond ended up being a T-tail only shop?
 
asicer said:
And then after the 70's T-tails got a bad name, which makes me wonder how Diamond ended up being a T-tail only shop?
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It's motorglider heritage I expect.
 
T-tails are borne out of ergonomics convenience (loading aft doors, jet blast avoidance et al), and suffer from aerodynamic penalties (high AOA blanketing, inferior low speed pitch authority, heavier overall structural weight) and aeroelastics-inferior (flutter at a lower TAS).

Beyond those cases where logistics drive the decision to undergo the opportunity cost, many more have been installed due to sheer novelty perception. Yes, design decisions in the biz class can be that gratuitous. Piston manufacturers dabbled with that behavior in the 70s as has been highlighted.
 
hindsight2020 said:
T-tails are borne out of ergonomics convenience (loading aft doors, jet blast avoidance et al), and suffer from aerodynamic penalties (high AOA blanketing, inferior low speed pitch authority, heavier overall structural weight) and aeroelastics-inferior (flutter at a lower TAS).

Beyond those cases where logistics drive the decision to undergo the opportunity cost, many more have been installed due to sheer novelty perception. Yes, design decisions in the biz class can be that gratuitous. Piston manufacturers dabbled with that behavior in the 70s as has been highlighted.
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If you are an aeronautical engineer I will believe you.
If not, this is ridiculous.
 
Pilawt said:
Engine accessibility for maintenance is important. Fuselage-mounted engines check that box.
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I believe one of the main reasons for fuselage mounted jet engines vs under the wings is less asymmetrical thrust when an engine is shut down. Similar principle to counter rotating engines on the Piper twin that came out in about 1970 with the downward prop blade closest to the fuselage, exception being the P -38 where they were rotating the wrong way (downward blade closest to the wing tips) in order to improve fighter performance but made both engines "critical" engines.
 
ateamer said:
Cessna Citation.
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True, until you get into the faster citations. I'm not an engineer so take it for what it's worth, but I am well versed in most citations.
The 525 is a mystery....
The 680 moved the stab to mid level, and it's assumed because of engine thrust.
The 750 has a true T tail, but that adds an entire can of worms to arrest dutch roll.
 
Well some interesting info shared..thanks
 
A couple people mentioned horizontal stabilizer position as a function of rear cargo door.. but I am not sure I see thee connection. There are plenty of rear loading purpose built cargo transports with fuselage mounted stabilizers... here below are just a few that come to mind.. I didn't list the C-119 flying boxcar.. cool plane but not sure what category "boom mounted" stabilizers go o_O

C-123
upload_2017-5-20_10-22-46.png

C-130
upload_2017-5-20_10-14-4.png

C-160
upload_2017-5-20_10-12-24.png
An-125
upload_2017-5-20_10-13-23.png
An-22
upload_2017-5-20_10-15-17.png
An-12
upload_2017-5-20_10-17-25.png
An-70
upload_2017-5-20_10-27-35.png
 
Don't forget the early t-tail 757 design....
19050.jpg
 
Tantalum said:
A couple people mentioned horizontal stabilizer position as a function of rear cargo door.. but I am not sure I see thee connection. There are plenty of rear loading purpose built cargo transports with fuselage mounted stabilizers... here below are just a few that come to mind.. I didn't list the C-119 flying boxcar.. cool plane but not sure what category "boom mounted" stabilizers go o_O
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The C-130 tail actually gets in the way of loading, and was part of the cause of a fatal accident several years ago.
 
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I am not an aeronautical engineer. Started life as a ramp rat and eventually got my A&P then progressed to IA. What I have seen is fuel controllers go wild on turbines and fry the horizontal stabs to the point of rendering an aircraft incapable of controlled flight. A rare occurrence for sure but something worthy of consideration for those who design and build them.

My two cents worth.
 
Cooter said:
The C-130 tail actually gets in the way of loading, and was part of the cause of a fatal accident several years ago.
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Interesting, I had no idea. Can you post a link to the accident? I'd be curious to read up on it so I can better understand the effect of the tail and loading
 
Tantalum said:
Interesting, I had no idea. Can you post a link to the accident? I'd be curious to read up on it so I can better understand the effect of the tail and loading
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The accident was pilot error, but the design of the tail led to unsafe practices by the aircrew. There isn't any aerodynamics discussion in the link if that's what you're looking for but interesting nonetheless. Here's the link:
https://www.airforcetimes.com/story...-forgotten-night-vision-goggle-case/83182244/
 
CC268 said:
The most important thing is to never assume a planes tail position identity. The plane should decide for itself whether it wants to be a t tail or normal tail
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Based on observations made in habitat such as New Orleans I suggest that one exercise caution when identifying t-tail and split-tail in the field. While many folks may consider things such as this to be trivial under certain circumstances significant errors have been made. The consequences of such errors include attempts to operate equipment with somewhat unfamiliar control inputs and performance results. As I understand it all phases, namely start-up, departure, cruise, arrival, and shutdown are significantly different. I have no direct experience and can only pass along hearsay on this matter. Perhaps those with firsthand knowledge can speak up?
 
Clark1961 said:
Based on observations made in habitat such as New Orleans I suggest that one exercise caution when identifying t-tail and split-tail in the field. While many folks may consider things such as this to be trivial under certain circumstances significant errors have been made. The consequences of such errors include attempts to operate equipment with somewhat unfamiliar control inputs and performance results. As I understand it all phases, namely start-up, departure, cruise, arrival, and shutdown are significantly different. I have no direct experience and can only pass along hearsay on this matter. Perhaps those with firsthand knowledge can speak up?
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One time I assumed the tail identity of my Cherokee 140 and ended up in a deep stall that I barely made it out of. Never again.
 
Cooter said:
The accident was pilot error, but the design of the tail led to unsafe practices by the aircrew
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Thanks, interesting to read through.. but really it was the pilot's failure to do a control check before takeoff.. "controls free, clear, and correct"

I still can't really picture what kind of cargo would need loading that can fit in the plane yet still have the stabilizer in the way.. granted I don't work around cargo planes
 
Because the F-104 and F-101 just wouldn't look right...along with some minor controllability issues.
 
Tantalum said:
Thanks, interesting to read through.. but really it was the pilot's failure to do a control check before takeoff.. "controls free, clear, and correct"

I still can't really picture what kind of cargo would need loading that can fit in the plane yet still have the stabilizer in the way.. granted I don't work around cargo planes
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While that would have prevented the accident, a flight control check was / is not part of the checklist.
 
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Velocity173 said:
a flight control check was / is not part of the checklist.
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Interesting, I wonder why not? Anytime I fly commercially I always see the ailerons and spoilers pop up and down at some point during the taxi. So I kind of just assumed all planes both large and small do a control check
 
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