[dmk0210]

It's my understanding that the Turkey Feathers were a maintenance problem of some sort on the F-15 and all were removed from the fleet in the early 1980s.

Why were the exhaust petals only a problem on the F-15 and not other aircraft?

This post has been edited by dmk0210: 21 June 2012 - 08:58 PM

[Pete]

Not the same engine, but they were removed on the B-1B's too. No idea why though.

[fasteagle12]

The is from a Cybermodel F-15C kit review:
Exhaust nozzles - The USAF F-15s are powered by the Pratt & Whitney F100 engine, the same powerplant as the F-16A/B and the F-16C/D Blocks 25, 32, 42, and 52. The Pratt F100 has 'turkey feathers' to streamline the exterior of the engine nozzle to avoid airflow drag. While the F-16s still retain these turkey feathers on their nozzles, testing revealed that the absence of turkey feathers on the Eagle did not contribute significant drag in flight but their removal saved manhours of maintenance. At some point early in the Eagle's career, the turkey feathers were removed from USAF Eagles. The Japanese retained their turkey feathers on the F100 engine for a number of years later, but they too are now removed. Israeli and Saudi Arabian Eagles still retain their turkey feathers.

I've heard weight and complexity were contributors to their removal.

[Ol Crew Dog]

As previously stated we were having trouble on our BPO (basic post flight) inspection checking for cracks on the divergent and convergent seals on the nozzles.
We started to remove the turkey feathers about 80 - 81 time frame. All where removed by 82 except those darn finger seals, was still breaking them off on my A model in 82.

[Dave Williams]

The Israelis retained the turkey feathers for a long time (probably to the early-mid 2000s), but now they are commonly removed, especially for operations in and around Israel. If they are installed, it's usually for long distance ferry flights. One caveat is that F-15Is all have the turkey feathers.

[Netz]

My partner in crime was working in the GE shop when they started having problems with the F-15 T/Fs getting ripped of by turbulent airflow, that was the main reason for their removal. (Note this is from my poor recollection explained to me a number of years ago)
The IDF on-off deal is bogus,don't know why it keeps getting recirculated.
Curt

[Ol Crew Dog]

I heard the same thing about the off an on of the turkey feathers, talk about a pain to do constantly. Figuered that was a myth.
I though the Israeli F -15 retained theirs due to the sand problem, I know how sand can be a problem from DS.....

[Netz]

I think what Mike mentioned was that if the engines were changed the T/F's remained on that specific engine till they found a problem, then the T/F would be removed, thats probably why you might see a specific airframe with and with out the t/f, they just changed engines to one that still had the t/f's (on or off).
Curt

[Ol Crew Dog]

The newer I and S models when delivered had completely different turkey feathers ( different engines ofcourse) and retained theirs.

[strikeeagle801]

And after a while, the S models got rid of theirs too. Of course, now, they are GE powered, and have turkey feathers again. The SA models will also be GE powered.

Aaron

[ya-gabor]

Back long time ago there was a longer article in Flight International on the Turkey feather issue. Many were lost in flight. The cost of the individual feathers was mentioned in the article and it was a nice sum. After the loss of each one they had to write long reports, mainly due to the cost of replacement. In the end a decision was made to take them off completely but also since they did not impair the flight characteristics of the aircraft, it was not a problem.

One would have to look into the archives to find the article.

Best regards
Gabor

[dmk0210]

Ol Crew Dog, on 21 June 2012 - 11:37 PM, said:

As previously stated we were having trouble on our BPO (basic post flight) inspection checking for cracks on the divergent and convergent seals on the nozzles.

Were those part of the Turkey Feathers, or did the replacement of the bad parts require removing the TFs?

[GEH737]

So - if they were a problem on the F-15, wouldn't the same issue have been present on the F-16? If so, why wasn't the problem addressed the same way?

[jmel]

GEH737, on 22 June 2012 - 04:07 PM, said:

So - if they were a problem on the F-15, wouldn't the same issue have been present on the F-16? If so, why wasn't the problem addressed the same way?

The Viper has different aerodynamics in that area and it never posed a problem with the turkey feathers.

Jake

[Andre]

GEH737, on 22 June 2012 - 04:07 PM, said:

So - if they were a problem on the F-15, wouldn't the same issue have been present on the F-16?

Not necessarily - completely different airframes, completely different aerodynamics.

Edit: well, if someonee has to beat me to the punch, at least is one of our resident F-16 gurus.

Cheers,

Andre

This post has been edited by Andre: 22 June 2012 - 04:28 PM

[BMH]

fasteagle12, on 21 June 2012 - 09:48 PM, said:

The is from a Cybermodel F-15C kit review:
Exhaust nozzles - The USAF F-15s are powered by the Pratt & Whitney F100 engine, the same powerplant as the F-16A/B and the F-16C/D Blocks 25, 32, 42, and 52. The Pratt F100 has 'turkey feathers' to streamline the exterior of the engine nozzle to avoid airflow drag. While the F-16s still retain these turkey feathers on their nozzles, testing revealed that the absence of turkey feathers on the Eagle did not contribute significant drag in flight but their removal saved manhours of maintenance. At some point early in the Eagle's career, the turkey feathers were removed from USAF Eagles. The Japanese retained their turkey feathers on the F100 engine for a number of years later, but they too are now removed. Israeli and Saudi Arabian Eagles still retain their turkey feathers.

I've heard weight and complexity were contributors to their removal.

I saw a picture in a book (remember those?) of a Saudi F-15C presumably during Desert Storm (three bags, 8 live missiles, mid 90s book), and it was featherless.

[Ol Crew Dog]

dmk0210, on 22 June 2012 - 03:01 PM, said:

Were those part of the Turkey Feathers, or did the replacement of the bad parts require removing the TFs?

Harder to inspect the nozzles when doing an "Auggy" inspection. The turkey feathers cover the convergent and divergent seals.
When you see a turkey featherless nozzle, what you see are the con and div seals.

[Ol Crew Dog]

ya-gabor, on 22 June 2012 - 12:25 PM, said:

Back long time ago there was a longer article in Flight International on the Turkey feather issue. Many were lost in flight. The cost of the individual feathers was mentioned in the article and it was a nice sum. After the loss of each one they had to write long reports, mainly due to the cost of replacement. In the end a decision was made to take them off completely but also since they did not impair the flight characteristics of the aircraft, it was not a problem.

One would have to look into the archives to find the article.

Best regards
Gabor

I was working on the F-15 asaCrew chief when this happened and did the investigation. Was a major pain to do a dropped object report with safety and the FAA involved

[Ol Crew Dog]

ya-gabor, on 22 June 2012 - 12:25 PM, said:

Back long time ago there was a longer article in Flight International on the Turkey feather issue. Many were lost in flight. The cost of the individual feathers was mentioned in the article and it was a nice sum. After the loss of each one they had to write long reports, mainly due to the cost of replacement. In the end a decision was made to take them off completely but also since they did not impair the flight characteristics of the aircraft, it was not a problem.

One would have to look into the archives to find the article.

Best regards
Gabor

I was working on the F-15 asaCrew chief when this happened and did the investigation. Was a major pain to do a dropped object report with safety and the FAA involved

[iaf-man]

Ol Crew Dog, on 22 June 2012 - 02:02 AM, said:

I heard the same thing about the off an on of the turkey feathers, talk about a pain to do constantly. Figuered that was a myth.
I though the Israeli F -15 retained theirs due to the sand problem, I know how sand can be a problem from DS.....

I've read somewhere that retaining the T/F decreases the IR signature.
Isaac