The Windecker Eagle is a four-place, low-wing monoplane powered by a 280-hp Continental IO-520-C flat-six cylinder piston engine. It had a maximum speed of 211 mph. The Eagle was first flown on October 7, 1967. One was acquired by the USAF under the designation YE-5A. The aircraft was made of plastic and had a three-bladed propeller of composite construction. It was used to evaluate the radar signature of an all-plastic aircraft (The Complete Encyclopedia of World Aircraft).
The following information was provided to me on 6/29/2008 by Ted Windecker:
I was the project engineer on the development of the stealth technology at Windecker ... I am an aerospace engineer and Dr. Leo Windecker is my father. We delivered two stealth prototypes to the military, one to the Army (Code-named CADDO, delivered in 1972, it was tested at Aberdeen Proving Ground, MD) and one to the Air Force (designated YE-5, it was delivered in February 1973 and began its testing at Eglin AFB, FL). Both were highly modified to be stealthy because the original Eagle was built to insure that it could be picked up on air-traffic control radar. We never had a problem with the "civilian" Eagles being picked up on radar. The YE-5 benefited from the Army work and was significantly more stealthy than the CADDO.
Dad originally proposed a stealthy, composite airplane to President Kennedy's science adviser for aviation in 1962. There was no apparent interest. He again proposed it to Congressman George Mahon in 1971, when he had an actual airplane that could be tested (his personal Eagle, N4195G, now in the Lake Jackson, Texas Historical Society Museum). Congressman Mahon pitched the idea to Air Force Gen. Otto Glasser, at Wright Field. They tested N4195G at the Air Force's RATSCAT facility in New Mexico. The development of the YE-5 was funded by DARPA.
I am writing the actual history of the Eagle project, since I was with the company during the whole development, going back to 1956 when my Dad started experimenting with composite aircraft structures in our garage in Sugar Land, Texas. Dad has a photographic memory, even at 87, and is providing an enormous amount of help, too.
The Eagle was not certified for only two people, even though that has been widely, erroneously reported. The Eagle had no restrictions on its certification and we delivered every one with four seats, including the two stealth prototypes. The FAA required us to test the Eagle to 120% of the strength requirement for an aluminum airplane and it passed every test.
The stealth prototype Eagle was actually used in real missions "across the pond," although extremely little, if anything has been published about that.
First, the Eagle was significantly fasterthat the Cessna 210 and the Beechcraft Bonanza, not slower. We were about 10-mph faster than the 1970 V-35 Bonanza . We had fighter-pilot chevrons on the side of the prototype to prove it. See the article in the May 1970 issue of Flying Magazine that shows the Bonanza, 210 and Bellanca chevrons, placed there after we outran them in side-by-side tests. It is true that we did no wind-tunnel testing. No small aircraft manufacturer did, back then. Computer aerodynamic analysis, known as CFD (Computational Fluid Dynamics) did not even exist. Remember, this was 1965! The wing was designed for docile low-speed characteristics (constant-chord, no twist, thick, low-speed airfoil). The wing was, from a top-speed point of view, very inefficient. The statement that the wing was "prone to wrinkling under loads" is absolutely not true. I cannot imagine where that came from, certainly not from someone who was there! The fuselage was 10" wider and 24" longer than the Bonanza, much roomier, by design because my Dad was a big guy. (The Eagle fuselage is actually larger than the 6-place A-36 Bonanza and the 6-place Piper Saratoga.) Still, we were faster than any other 285-Hp, 3,400 lb. gross-weight airplane on the market! After certification, we designed a tapered wing (much higher aspect ratio, more efficient airfoil) that was calculated to add 10 mph to the top speed, already 10 mph higher than the Bonanza!
It is true that the airplanes were a little heavier than the 210 and Bonanza. Really, this was the fault not of the FAA, although we were required to make it 20% stronger than those airplanes, but, rather, our very conservative design approach. We did not have the luxury of millions of dollars to get through certification with the conventional approach of "underdesign, test, fail, beef-up, test, fail, beef-up," that was common at Cessna, Beech and Piper (Our chief engineer, Bill Shackleford, and our test-pilot, Bill Robinson, both came from Cessna). So we overdesigned, and passed almost every structural test the first time without "beef-up." Hence, a heavier than necessary structure. After certification, we successfully tested a modified wing design that was still 20% stronger than the others but was 200 lbs lighter than the certified wing.
The story, originally reported in the 1970 Flying Magazine article, that the wings were the lightest wing structures known and somehow contributed to the spin crash is just absolutely wrong. The wings were very heavy. The wings had nothing to do with the spin crash. I know, because my brother and I did the analysis of what caused the uncontrollable aft-cg, gross-weight spin and I designed the fixes that were implemented on the certification prototype (N803WR). The fact that 803 was spun 177 times, more than any other aircraft ever up to that time, attests to the fact that we solved the problem.
The company failed, not because we couldn't sell the airplane, although 1970 was a recession year in general aviation, but because the West-Texas Oilmen who owned the company grossly undercapitalized it, wasted what money they did have and then failed to do what was necessary to recapitalize it (there were many offers from very reputable financial houses)!
Even today, almost 40-years after it was certified, the Eagle compares very favorably with all-composite airplanes from Cirrus and Columbia (now owned by Cessna). It is larger and has retractable gear, but the empty weight is 100-lbs lower!
By the wy, the airplane in the Army Aviation Museum at Ft. Rucker is not the YE-5. The YE-5 was destroyed during a classified project in 1985. The airplane at Ft. Rucker is civilian Eagle N4196G (Serial Number 5), which was purchased from its original owner, modified to complete the classified project, and then returned to Ft. Rucker!
As of 2008, three Windecker Eagles remain on the US Civil Aircraft Registry:
- N4197G is registered to the Smithsonian Institute's Air & Space Museum
- N4198G is registered to Commerce & Trade, Inc. - a Delaware Corporation
- N804WR is registered to Commerce & Trade, Inc. - a Delaware Corporation
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