There have been a number of posts recently that I have been tempted to get into but stopped for fear that by saying that I did it first over and over, I might make my points but lose creditability on the basis of poor personality.
Richard Oliver and I have been corresponding a bit recently about stunt ship design. I wrote this as an e-mail to Richard, and then decided, "what the heck?", I'll stick it on Stuka Stunt.
For what its worth, here is my opinion of a watershed event in stunt ship design.
I designed the molded Mustang, later referred to as Snaggletooth in the fall of 1973. I feel that airplane had these notable features:
1 It was a relatively small aircraft with carefully computed moments and areas. Its 55" wings were highly loaded with full span 25% flaps and enough lift the win the 1977 NATs, Walker Trophy and second in the 1978 World Championship,
2 It was groovy and stable. I used the same tail volume coefficient in its design that Brett Buck uses today, (.4).
3 After a couple of NATs winning Sea Furys which had no wing asymmetry, I was a strong believer that the 1"-2" typical of the time was too much. The Mustang was built with 1/2" of asymmetry and had 1/8" wider tip on the outboard flap. Sound familiar? Incidentally, all of this information was in an American Aircraft Modeler article in 1978. My reasoning for the Mustang’s various features were explained in the article. The design elements were original but not secret.
4 The airfoils used were typical of those used on the Sea Fury and based on auto hood top tests. They were "profiled" with moderate leading edge radius. Which is to say, the airfoil used was smoothly curved between the high point and wing trailing edge to minimize the discontinuity between the wing and a deflected flap. Airfoils shown in the article were atypical of the time but would be considered quite up to date now.
5 The tank described in the article was original, novel and new. It was built with the rear outside corner intentionally displaced toward the outboard side of the aircraft. The explanation in the article reasons that by making the tank more nearly tnagent to the flight path, as opposed to paralleling the airplane's centerline, there would be less fuel remaining after the cloverleaf. In fact there was so little fuel left after the cloverleaf that I was able to complete the maneuver, fly two level laps and reliably stop the engine by looping the Mustang. At the time, my movable rudders were adjusted to remove only part of the nose out yaw on inside maneuvers and to overcompensate the inward yaw on outside maneuvers to impart a nose out on outside maneuvers as well. With little fuel remaining in the tank any nose out yaw would cause the remaining fuel to run to the front uncovering the pickup and stopping the engine. It worked so well that there was talk about the legality of my tank and looping maneuver to stop the engine at the FAI team trials.
This feature of tank design was so noticeably effective that it was soon copied by many competitors. Whether the tank rear is slewed toward the outside or built with wedge fashion with a wider rear end to the tank, the result is the same, cleaner cuts. Curiously, it doesn't seem very effective with clunk tanks.
6 The 1973 Mustang design, E2-S, the first of the Snaggletooth series airplanes, featured a removable wing with screw adjustable length pushrod and variable flap/elevator ration adjustments. These trimming devices had been used previously on the 1967 Mustang I, the Bearcat III, and both Sea Furys.
7 The design of that Mustang series also featured intentional stabilizer incidence. It was theoretically and practically desirable and worked well. This is the first time that I am aware of that incidence was intentionally used to balance inside and outside turning rates on a stunt ship and the reasoning described in a widely distributed article.
8 The design also included shock gears, internal muffler, canted engine, movable rudder, tipweight box and the sliding block adjustable leadout guide that I originated in 1969.
9 Modern stunt ships are somewhat characterized by powerful engines. The 1973 Mustang was a small airplane with a 55" span, built to be competitively powered with a S.T. 46. Soon it was flying with "stroked" 46 of .51 displacement. Its final competitions were flown with an engine designed and assembled by me of stock and custom parts. It was true .60 displacement and timed for stunt. My home made .60 was built to fit into 46 mounts and energetically turn a 13” wide blade prop. This small Mustang with its .60 was very powerful for the 1970"s and roughly equivalent to today's more competitive airplanes.
10 It looked pretty good, which never hurts.
What possible feature or characteristic of modern stunt ships did I fail to anticipate 33 years ago. Why wouldn't this airplane be considered the father of the modern stunt ship? And for good measure, the article should be required reading for stunt flyers interested in design (it was reprinted in Stunt News in 2000)
Al
Topic: Is This the Father of Modern stunt Ships (Read 16517 times)
