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From "About the Thorp"
http://t18.net/thorpforum/viewtopic.php?f=21&t=6854		 Page 1 of 1
Author:  fulcrumflyer [ Mon Dec 05, 2011 9:09 pm ]
Post subject:  From "About the Thorp"
Can anyone confirm that this is really true? "The T-18 incorporates the 'flying tail' which John Thorp held the patent for." Is this actually just urban legend? The flying tail has been around since the Wright Brothers. They used flying tails on all their aircraft until their 1914 Wright Model G. That was the first time they used a horizontal stabilizer with a hinged elevator. In fact, the G-model was the first aircraft to utilize a t-tail configuration. The Century-Series fighters such as the F-100,F-104 and F-105, developed in the early-to-late 1950s, had flying tails and flew well before the T-18. Just wondering.
Author:  leewwalton [ Mon Dec 05, 2011 9:25 pm ]
Post subject:  From "About the Thorp"
Yes that is true. John Thorp patented the flying tail while he was at Lockheed, he left Lockheed in 1946. I guess you could make the Wright Brothers argument but that's might be stretch.

Here's a link to the patent

http://www.google.com/patents?id=_HxVAA ... &q&f=false
Author:  jrevens [ Mon Dec 05, 2011 9:27 pm ]
Post subject:  From "About the Thorp"
There are "flying tails", and then there are "flying tails". There were many Thorp designs before the T-18. I believe that what we're talking about is the modern stabilator with associated anti-servo tab, etc. No, it is not an urban legend.

John Evens N71JE
Arvada, CO
Author:  leewwalton [ Mon Dec 05, 2011 9:29 pm ]
Post subject:  From "About the Thorp"
Before I get in trouble for the Wright Brothers comment ...

My reasoning in that is that the canards on the Wright Brothers airplanes pivoted at the leading edge rather than at the center of lift (or near it). So they were not so much "flying" as deflecting air up and down (like an elevator).

... Just an observation.
Author:  jrevens [ Mon Dec 05, 2011 9:48 pm ]
Post subject:  From "About the Thorp"
I could be wrong, but I think, perhaps, that the Wright Flyers had elevators that were hinged somewhere near the center of the structure, & probably "floated", or "flew" also. Someone please correct me if that's wrong. Again, a major difference is the anti-servo tab & associated linkage, giving the desired "feel" & causing the deflected surface to return to the trimmed position. Brilliant.
Can you imagine flying a T-18 or any other all moving-tail equipped airplane without that basic characteristic?

John Evens N71JE
Arvada, CO
Author:  leewwalton [ Mon Dec 05, 2011 10:09 pm ]
Post subject:  From "About the Thorp"
I'm sure you're right John/Spanky .. I was visualizing the canard on the original Flyers but come to think of it, the model B and laters did have a horizontal tail that could be argued "flew".
Author:  fulcrumflyer [ Mon Dec 05, 2011 10:49 pm ]
Post subject:  From "About the Thorp"
Lee,
Thanks for the link to the patent. I'm sure he developed his anti-servo trim system on his free time or Lockheed would've had something to say about that. Our time, our mney. John is right, the anti-servo system makes the airplane easier to fly and is essential in an open-loop flight control system such as on the Thorp. A closed-loop system, as in a hydraulically-actuated system on a modern fighter, doesn't need an anti-servo trim tab as John mentioned as the undesirable feature of an all-moving tail surface without an anti-servo trim system. The trim button in those aircraft changes the position of the control surface and there is no direct feedback to the pilot except through an artificail feel system.
The canards on the Wright airplanes are flying surfaces from an aerodynamic standpoint. It doesn't matter that the canards are out front versus a conventional layout. A horizontal stabilizer is a horizontal stabilizer regardless of where it is. I'm not sure why the Europeans are so infatuated with cnards on their fighters.
Also, an elevator on a hinged system doesn't just deflect air (I'm not sure if that's what you really meant). Moving the elevator changes the camber and angle-of-attack of a lifting surface which is the horizontal stabilizer/elevator combination. When the trailing edge of the elevator goes up, it produces negative lift on the tail surface, increases the angle-of-attack on the main wing and we know what happens then. Likewise, on the Wright designs, when the horzontal stabilizer changed angle-of-attack, lift increased or decreased on the surface.
Again, thanks for the answer. I was looking at just the all-moving hotizontal tail surface as a whole, which had been used before, and not thinking about the trim system that Thorp developed.
Author:  leewwalton [ Tue Dec 06, 2011 7:27 am ]
Post subject:  From "About the Thorp"
I agree, I John is right on the "sum of the parts" making Thorp's design patentable.

As to the comments I made on the Flyers ... It was not the location of the pitch control (canard or aft) I was referring to but the actual mechanics of the original Flyers canard. If you look at it, it's hinged at the leading edge, like an horizontal tail/elevator without the non moving surface. My impression of a "Flying" surface is that it pivots at (or close to) the center of lift on the surface. The deflection comment was a bad choice of words, I of course realize that all surfaces on aircraft create lift. To me it looks like the Wright Brothers got lucky on the first flight and then changed the pitch control soon there after. Of course I'm out of my league aerodynamically here so forgive my novice observations/comments.

As to the patent though, if you read it it's not just the anti-servo tab that's patented. It's definitely the "all flying tail". I think both you and John nailed it, the "flying tail" you're used to on the fighters may not qualify as it is somewhat "cheating" with hydraulics rather than aerodynamics.
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