I would like to summarize what I have read and what I have experienced. As suggested by Brett early on in this thread, this subject comes up every several months or so. Brett also gave how to access the long thread that started last April. There is some good information in that.
Also in this thread have been the statements that all-flying stabilators are being used in full scale aviation, including lights planes (some Pipers for example), gliders and supersonic aircraft.
In the case of the light planes and gliders, an all-flying stabilator allows the use of a smaller horizontal tail surface, thereby reducing drag. Those aircraft are not looking for extreme maneuverability and recovery stability after completing a hard inside or outside maneuver. In the case of the sailplane, the reduced drag is probably a paramount consideration and the likely increased structural weight to accommodate the stabilator is not a major problem.
In the case of supersonic aircraft, the stabilator is used for an entirely different reason. Primarily, the stabilator provides positive longitudinal control in the high sub-sonic and supersonic regimes where compressibility and the formation of shock waves seriously impact the effectiveness of a conventional horizontal stabelizer/elevator configuration.
It is interesting to note that full scale aerobatics designs typically do not use the all-flying stabilator.
I played around with an all-flying stabilator in the late 50's when I was in college.. (Though I will have to admit that I did not know much about flying a competition pattern - some will say that I still don't - but I knew a lot less then.) I had two models, basicly the same design, one with a stabilator and the other with a conventional tail. There were structural problems, added weight, and I felt the model with the conventional tail flew better. Enough so that I have not ever felt it necessary to try it again.
In the same thread that Brett referenced above, "Bare" explains quite well the differences between combat and stunt models and what is expected of a stunt model. (These combat guys sometimes come up with some pretty good stuff.) Anyway, "Bare" states:
"tails are longer and larger to overcome the flaps opposite pitching moment and to stop the model from rotating at the precise moment. Part of the tail function in stopping the maneuver is supplied by the stabilizer acting as arrow tail feathers to maintain that straight line for which you are searching. A stabilator does not have this built in stabilizing effect. A stabilator would not be particularly worthwhile to experiment with on a precision aerobatic ship, because you would never find the necessary recovery stability to match the current stab/elevator combination."I think another way to explain this is that the general consensus of some who have tried all-flying stabilators on a stunt ship is that they do not allow the model to precisely track through a maneuver nor to recover "flat" when completing a maneuver, particularly from the square turns.
As Ted suggested ealier in this thread and has been discussed in other threads, there are structural problems to overcome with attendant weight increases in a location that normally needs to be as light as possible. Then Tom McClain comes along with his "F-104" with the all-flying high T-tail stabilator. Maybe he is on to something that nobody has yet found about how to get a stabilator to work better on a stunt ship than a normal stab/elevator configuration. There may be solutions out there not yet refined that could pave the way to a "major revolution" in the pondorously slow evolution of CL stunt design.
Keith
Keith
