Windecker Aircraft

Windecker X-7 :low wing four seat light aircraft with fixed tricycle undercarriage
and a 290 hp Lycoming IO-500 engine (later developed into AC-7
with retractable undercarriage,redesigned the wing and 285 hp
Lycoming IO-520 engine).

Anyone here have color images of the old Windecker/USAF YE-5A Eagle aircraft from 1973? The only image I have access to is very grainy and B&W. Anyone?

Vulture

I'm not sure I ever saw a color pic of that one... Also, the information about that bird that is circulated is contradictory. According to the site Eagle behind the curtain, the YE-5A prototype was "destroyed during a classified test in 1985", but other sources such as Wikipedia state that it "is preserved in the U.S. Army Aviation Museum at Fort Rucker, Alabama"...

Bingo! Google is my friend... ;D





Source

Thanks you guys!!! I kjnew someone here had color images of that beautiful aircraft - and information to boot - again thanks!! B)

Vulture

Just got a mail from Ted Windecker, son of Leo, who was project Project Engineer on the design and development of the YE-5. Here is what he says about the aircraft at Fort Rucker Museum:

Good morning, Stephane.
The airplane in storage at the Army Aviation Museum is Windecker Eagle S/N 005, N4196G, not the YE-5. The YE-5 was a highly modified Windecker Eagle, S/N 009. Sometime in the late '80s (I don't remember the exact year off the top of my head) the YE-5 was loaned to a group for testing. During those tests, I am told, the pilot lost control of the YE-5 during an intentional spin and bailed out. (Because of the extensive modifications that significantly altered the airplane's weight and balance, the YE-5 was placarded against intentional spins.) The airplane was so badly damaged in the crash that I deemed that it could not be returned to flight. I suggested to the group that they buy '96G to complete the tests, which they did. They then returned '96G to the Museum, as was their agreement.

'96G was originally delivered to our dealer in Boulder, CO in early 1971. They sold it to an individual in Cincinnati, OH who sold it to the group testing the YE-5. I have not seen '96G since it was acquired by the Museum, but there are some hints in the photograph that it has been modified as a result of the tests back in the '80s.

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Thanks Stargazer!! for the images and info - very helpful, especially the personal words of Ted Windecker.

Vulture B)

Do we know if the YE-5A was externally modified, or just internally? I am thinking of trying to design a 1/72 3D printed model of it, and have some drawings of the civilian eagle, but the lack of HD photos of the YE-5, I am grasping at straws.

Orionfield said:

Do we know if the YE-5A was externally modified, or just internally? I am thinking of trying to design a 1/72 3D printed model of it, and have some drawings of the civilian eagle, but the lack of HD photos of the YE-5, I am grasping at straws.

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There were not significant changes to the outer mold line. There was a different prop and internal changes that altered the CG.

Is there a good reference for the propeller difference?

vulture said:

Anyone here have color images of the old Windecker/USAF YE-5A Eagle aircraft from 1973? The only image I have access to is very grainy and B&W. Anyone?

Vulture

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Rhetorical question: how does one take a color photo of an all-white airplane?
Hah!
Hah!
Most composite airplanes are all-white.

riggerrob said:

vulture said:

Anyone here have color images of the old Windecker/USAF YE-5A Eagle aircraft from 1973? The only image I have access to is very grainy and B&W. Anyone?

Vulture

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Rhetorical question: how does one take a color photo of an all-white airplane?
Hah!
Hah!
Most composite airplanes are all-white.

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But the YE-5A was painted blue. And I can see that it had a 3 blade prop, as opposed to the 2 blade stock version of the Eagle.

Why it was called at first YE-7 ?.

hesham said:

Why it was called at first YE-7 ?.

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It's YE-5, not 7. This was a standard USAF designation in the post-62 EW series.
E-1 tracer, E-2 hawkeye, E-3 sentry, E-4 aacp, ...

dan_inbox said:

hesham said:

Why it was called at first YE-7 ?.

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It's YE-5, not 7. This was a standard USAF designation in the post-62 EW series.
E-1 tracer, E-2 hawkeye, E-3 sentry, E-4 aacp, ...

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No my dear Dan,

it was YE-7,may be inhouse designation ?.

hesham said:

it was YE-7,may be inhouse designation ?

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Possibly. I have no info about it.

From Plane & Pilot March 2021:

"In addition to the first two prototypes, only six more Eagles were constructed. Of the eight total airframes, one was lost in testing, three are in museums, and thankfully one was fully restored to fly- ing condition in 2015."

"As in all really good stories, there is a top-secret side. The U.S. Air Force purchased a military version of the Eagle and later transferred it to the Army. As it turns out, Leo Windecker understood the stealth value of composite materials and convinced the military to take a look. The aircraft, dubbed the YE-5, was pylon tested against radars at Holloman AFB, New Mexico. Of course, the test results were classified. However, Windecker Industries earned a follow-on contract to construct 36 composite “Laser-Target Designator” Remotely Piloted Vehicles (RPVs) for the Army. Sadly, none of this saved Windecker Industries."

According to the Smithsonian:

"The Air Force really wanted the YE-5 airplane so that it could test the radar reflectivity and stealth characteristics of the all-composite construction. The Air Force transferred it to the U.S. Army which wanted to test it for possible use as a utility airplane. The airplane was then sent to the Army Aviation Museum for display. There was also a seventh civilian Eagle I being constructed, but it was never completed before the company went into receivership." https://www.si.edu/object/windecker-eagle-i:nasm_A19850619000

From Oklahoma Aviator:

"Sometime that year (1977), Dr. Windecker suggested to the U.S. Air Force that the composite construction of the Eagle might allow for a smaller radar return signature than metal airplanes. The Air Force subsequently tested N4195G at the RATSACAT test facility in New Mexico. The results were encouraging and the Air Force contracted with Windecker to deliver an Eagle, highly modified to further reduce the radar return. That airplane (S/N 009), designated as the YE-5 by the Air Force, was the last Eagle to be built. Thus, Windecker was an early participant in the development of the stealth technology that has become so successful today. In succeeding years, Windecker Research participated with Lockheed in the SAVOIR and AEQUARE Remotely-Piloted Vehicle (RPV) programs. In 1976, Windecker's Board of Directors suspended all operations and "closed the doors," withdrawing from the followon AQUILA RPV development." (Note: The picture I have is of N4195G being tested and not the airframe that the AF ordered designated YE-5 (i.e. with radar reducing internal components))

"The Air Force reported that the radar registered only the engine and the landing gear, not the plane's composite body. An Eagle, modified to reduce radar, infrared, acoustic and visual observables, was tested by the U.S. Army at Aberdeen Proving Ground, Maryland in 1972 under the code name CADDO. The results were compelling, prompting the U.S. Air Force and DARPA to order an Eagle built from scratch to minimize radar detectability. Windecker built Eagle serial number 9, incorporating numerous modifications to reduce its radar detectability, and delivered it in February 1973 as the YE-5 to the Air Force who tested it secretly for five years at Eglin AFB, Florida. It was then transferred to the Army, who continued testing its stealth application for many years. Eventually, the Army transferred the YE-5 to the Army Aviation Museum at Fort Rucker, Alabama. The YE-5 was destroyed during classified testing in the late 1980s. The Army Aviation Museum received Eagle serial number 5, N4196G, to replace the lost stealth prototype. Eagle N4196G is in storage at Fort Rucker and not on display."

Windeck YE-5

When it comes to this subject, it is often hard to separate fact from fiction. Over the years the story has been embellished by various authors and the Eagle (and Fibaloy) have taken on legendary properties. I recall back in the 1980s that Fibaloy was often cited as a magic stealth material. Even today you can find references on the Interweb saying the F-117 was constructed primarily of Fibaloy!

Supposedly, as early as the 1950s Leo Windecker was trying to interest DoD in an "invisible" airplane (without success). It wasn't until much later that Windecker, with Dow Chemical, developed Fibaloy and the Eagle.

In 1973 Windecker produced the last Eagle, Serial 009, for the Air Force. Before delivery to the Air Force it briefly had the civil registration N4188G. Sadly, the FAA did not retain records that may have described the modifications made to it for the Air Force. It did have a composite 3-blade prop, and supposedly had some amount of RAM mounted inside the aircraft. The aircraft was delivered to Eglin and assigned AF serial 73-1653 with a designation of YE-5. Supposedly this aircraft was lost in an accident in the 1980s. I have not yet been able to locate any official records of any such accident.

The US Army was interested in the Eagle at about the same time. The Army tested wether Fibaloy would work as a light, low RCS armor at Ft. Eustis. The Army also tested an Eagle at Ft. Eustis and Aberdeen for ballistic tolerance, RCS,IR, and acoustics under the "Plastic Airplane" project:

"DESCRIPTION AND RESULTS: This program provided for radar cross section measurements of a commercially available plastic aircraft to determine if fiber- glass reinforced plastic materials can be used to reduce the radar signature of an aircraft. The additional benefits of this new construction technique such as reduced infrared and acoustic signatures were also addressed.

The infrared measurements and static portion of the radar cross section
tests were completed with favorable results.
Evaluation of 40 sections of the aircraft by Ft. Eustis established that there is no spalling or crack propagation when aircraft sections are hit with 30 cal, AP and ball, at all angles of incidence. Dynamic radar cross section measurements were done in conjunction with NRL (Naval Research Laboratory) and the sensor package was installed and flight tested."

Now the important part here was not the RCS test results, or the fact that they got the Navy to allow them to use their dynamic RCS range. The sensor package is the key. As it turns out, that was the big reasons both the Air Force and the Army were interested in the Eagle. Both services wanted to install intelligence sensors inside the aircraft, using the structure as a radome. The Army payloads were both SIGINT and a radar system.

The Air Force YE-5 was tested at RATSCAT but most of the flying it did appears to have been in support of EW organizations.

The RCS of the Eagle was, as best I can tell at this point, not very good. The RCS *pattern* was different from other similar GA aircraft, but it was not much harder to detect with military radars.

Separately, the Army took delivery of a small RPV from Windecker in June of 1973. This was separate from the AQUARE, etc. programs and may or may not have been flight tested due to lack of funding.

There have been many references to Fibaloy being a stealth material, that there are boron or carbon doped version of Fibaloy that absorb radar, etc. This does not seem to be true at all. Fibaloy is a "glass reinforced plastic" (fiberglass) made for aircraft applications. No more, no less. It was effectively transparent to radar (which is not a good thing) but did not have any special absorbing properties. As far as I have been able to tell Fibaloy was never used on a stealth aircraft.

Fiberglass *is* used on stealth aircraft for edge treatments. The leading and trailing edges of the F-117, for example, were fiberglass covering a graded absorber

The Eagle was tested to support other more prosaic projects. N4198G was used by the Army to test antennas [in part for the upcoming ACAP helicopter program]. The issue was apparently how much groundplane was required to be applied to the composite, radio-transparent aircraft to yield similar performance as the antennas mounted on the same baseline metallic airframe design.

This was an increadibly interesting thread for me as I was only familiar with 97G (SN006). It was a beautiful plane. Very smooth in flight (partly due to the pilot, Frank Hale, and the beautiful Texas weather that day), but in-cabin air flow was not great and it got decidedly hot during our 45 minutes in the air. She had less that 1000 hours on the airframe when delivered to the Smithsonian.

dwalton1996 said:

This was an increadibly interesting thread for me as I was only familiar with 97G (SN006). It was a beautiful plane. Very smooth in flight (partly due to the pilot, Frank Hale, and the beautiful Texas weather that day), but in-cabin air flow was not great and it got decidedly hot during our 45 minutes in the air. She had less that 1000 hours on the airframe when delivered to the Smithsonian.

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Nice Info Dwalton,and welcome aboard.