Hi,
- I was to an air show awhile back. I was inspecting a Navy A6 Intruder. I caught the exhaust end of the tail pipe and noticed a circumference of mesh "feathers" on the inner ID, that honestly looked like dragonfly wings, gossamer in texture. I wonder what the function of this is, what the material is, and how is it produced? A stamping process is a guess. Material---titanium?
- No, I'm not into the inner workings of such.
- Thanks.
- Kurt {:{
Don't know how they're made but the tail feathers are used to form the variable geometry exhaust nozzle. They close down or open up to control the jet exhaust and hence thrust. I suspect that they are titanium
My understanding is those things are called "turkey feathers."
Jim
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The A6 uses the P&W J52 engine. Not an afterburning engine, so it's only a fixed-size nozzle.
It's an unusual short-tailpipe engine (for current-era designs), I don't know much about P&W engines, and the J52 is from the era when the USN wasn't talking to the USAF and insisted on having its own range of engines. So I can't say much about the tailpipe on it. it also showed up on the A4 aircraft and the Hound Dog missile.
Ti is fairly rare as sheetmetal on aircraft, especially around the hot end of engines. It's more likely to be a nickel alloy such as an Inconel or Monel (OK, so Monel K-500, has 0.6% Ti in it).
If there's a large forged or machined part in there, it might be Ti. These are the thrust reverser mountings from an RB-199 engine (Tornado),
BTW - If you want a J52 of your own:
-- Die Gotterspammerung - Junkmail of the Gods
Inconel would be my guess as well. I've got a bunch of misc pieces of Inconel spherical rod ends intended for aircraft engines that I got when doing a job for New Hampshire Ball Bearing. The engines that I've peeked into have an elaborate linkage with a bunch of tie rods connecting all the feathers together.
Ned Simmons
If I recall correctly, the A6 Intruder actually used a Pratt and Whitney J-52 P8 engine. The EA-6B Prowler used a J-52 P408, which had variable guide vanes in the intake to help "swirl" the air before entering the first stage compressor. I believe they were made to prevent the engine from "chugging", a term used for compressor stalls. However, both aircraft had the "feathers" around the exhaust. The maintenance crews called these "turkey feathers", but as more of a joke referring to variable vanes of afterburning engines. They actually are just a tailpipe seal. How do I know? Marine Tactical Electronic Warfare Squadron 2, MCAS Cherry point, NC 1978-1982 Semper Fi Ron
They just form a seal around the engine to the airframe. The F-16 uses sheetmetal pieces that form this seal, others I have seen use a high temp silicone seal. It mainly allows the engine to expand and contract or move with temp change and to form a more aerodynamic form.
Turkey feathers are used on thrust augmented type engines (afterburners) After burner is an old term, and has for the most part been taken over by augmentor.
While not directly related to the Intruder topic at hand, the F-16 has what is referred to as a dog bone, which is part of the engine mounting system, which prevents the motor itself from rotating under power. On the F-4 and other aircraft it was referred to as a tangetial mount, but anyhow this dogbone is made of titanium with two heim type ball joints at each end. The main body is approc 5/8 x 1 inch square stock approx 8" long, and the ball ends housing is formed on each end. These are routinely changed when worn in the ball ends. I acquired a few of them over the years and for just a simple item, they are machined and ground to unbelieveable tolerances, for just being a support. I cut the ball ends off and have just the rectangular shaped stock, and they make great paralells. Nice and lightweight, and non-magnetic. Oh and the government cost per dog bone is only $5,200 each. So I guess I have about $30,000 worth or parallells. Each and every one I have has been mic'd and all are more than close enough in size to be worthy of paralells and turer than I am capable of hlding tolerances in my shop to.
Why such tolerances on such an item is beyond me. Guess it has to do with the machines used to make em.
The turkey feathers seem to be a thin skin of titanium or haselooy or Inconel with a honeycomb between. I sure would like to see how that is made and assembled
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