N328KF From United States of America, joined May 2004, 6222 posts, RR: 3 Posted (7 years 7 months 2 weeks 9 hours ago) and read 2403 times:
With the GEnx and Trent 1700 replacing the CF6 and RB211, respectively, on many civil airframes, what are the chances we will see either of these engines being used for re-engining projects in the place of those two engines, as well as the TF39? Candidates include the KC-10, E-4, C-5, etc. (I obviously don't see them touching SAM 28000/29000.)
When they call the roll in the Senate, the Senators do not know whether to answer 'Present' or 'Not guilty.' T.Roosevelt
TheSonntag From Germany, joined Jun 2005, 3347 posts, RR: 30 Reply 1, posted (7 years 7 months 2 weeks 9 hours ago) and read 2394 times:
Since B52s still use the TF-33 (JT-3Ds), just like many E3-A Awacs, I really doubt C-5s will be re-engined, as military projects tend to use the "old crap" quite long time (which is great).
Ok, didn't know that. Whats the original engine? JT9Ds? If so, why are they re-engined? Wasn't the C-5 the first airplane ever to use high-bypass Turbofans?
WhiteHatter From , joined Dec 1969, posts, RR: Reply 4, posted (7 years 7 months 2 weeks 6 hours ago) and read 2348 times:
The GENx and Trent 1700 would not be ideal for the existing systems of the C-5. Purely for commonality reasons the CF6 is the ideal powerplant as the TF-33 is a close relative.
The RB211 was originally proposed for the B-52 but nothing came of it, specifically the -535E4 variant from the 757.
SATL382G From , joined Dec 1969, posts, RR: Reply 5, posted (7 years 7 months 2 weeks 6 hours ago) and read 2348 times:
Quoting TheSonntag (Reply 3): Whats the original engine? JT9Ds? If so, why are they re-engined? Wasn't the C-5 the first airplane ever to use high-bypass Turbofans?
The C-5 has been flying all these years with the TF-39, the first high bypass turbofan. The C-5 is the only airframe to use the TF-39. The TF-39 found more success as a marine powerplant (LM2500) than it ever did as an aircraft engine.
They are being reengined because the TF-39, being on one airframe only, was never seriously developed. The CF6, which sprang out of the TF-39 program, was and is in service on a number of commercial airframes. The benefit of the reengining to the C-5 is more power, better fuel economy, and ease of maintenance.
WhiteHatter From , joined Dec 1969, posts, RR: Reply 6, posted (7 years 7 months 2 weeks 5 hours ago) and read 2340 times:
Quoting SATL382G (Reply 5): They are being reengined because the TF-39, being on one airframe only, was never seriously developed. The CF6, which sprang out of the TF-39 program, was and is in service on a number of commercial airframes. The benefit of the reengining to the C-5 is more power, better fuel economy, and ease of maintenance.
There's also the worldwide availability of a parts bin for the CF6. Being able to source a part quickly in peacetime operations cuts costs down.
There are plenty of civilian operations with CF6 overhaul capabilities worldwide.
GDB From United Kingdom, joined May 2001, 12708 posts, RR: 80 Reply 7, posted (7 years 7 months 2 weeks 5 hours ago) and read 2336 times:
I've always been surprised they did not do a CF-6 fit when the C-5B was in production in the 1980's, retro-fitting C-5A's when they were re-winged too.
I guess they needed more airlift quickly, both new production and getting the original C-5A's fixed however.
AeroWeanie From United States of America, joined Dec 2004, 1600 posts, RR: 52 Reply 10, posted (7 years 7 months 1 week 6 days 21 hours ago) and read 2270 times:
Quoting SATL382G (Reply 2): It's happening as we speak, with CF6 though.
RayChuang From United States of America, joined Jun 2000, 7694 posts, RR: 5 Reply 11, posted (7 years 7 months 1 week 6 days 10 hours ago) and read 2226 times:
If I remember correctly, the engines the C-5's will get are the same engines used on the E-4B and VC-25A: the GE F103 turbofan, essentially a military version of the CF6-80 turbofan used on 767's, 747's and A330's.
F14D4ever From United States of America, joined May 2005, 319 posts, RR: 4 Reply 13, posted (7 years 7 months 1 week 6 days 4 hours ago) and read 2172 times:
Quoting RayChuang (Reply 11): If I remember correctly, the engines the C-5's will get are the same engines used on the E-4B and VC-25A: the GE F103 turbofan, essentially a military version of the CF6-80 turbofan used on 767's, 747's and A330's.
You did well from memory.
FWIW, there are turbomachinery differences between the F103 variants found on the E-4B and VC-25A. The E-4B and the KC-10 have military versions of the CF6-50, which utilizes a 3-stage booster. The VC-25A has an F103-102 which is a CF6-80C2B1, running a 4-stage booster. So while they are all called F103 by the USAF, they're NOT all CF6-80's.
To further discriminate, the C-5M will get a variant with the civilian nomenclature CF6-80C2L1F, which has the Full Authority Digital Electronic Control (FADEC).
TheSonntag From Germany, joined Jun 2005, 3347 posts, RR: 30 Reply 14, posted (7 years 7 months 1 week 6 days 1 hour ago) and read 2146 times:
Are there really differences between military and civilian engines? Obviously there are, but why? To make C-5s more FOD resistant, or are there other reasons?
Is the TF-33 of the Awacs identical with the JT-3D, or are there differences, as well?
F14D4ever From United States of America, joined May 2005, 319 posts, RR: 4 Reply 15, posted (7 years 7 months 1 week 5 days 12 hours ago) and read 2131 times:
Quoting TheSonntag (Reply 14): Are there really differences between military and civilian engines? Obviously there are, but why? To make C-5s more FOD resistant, or are there other reasons?
In the case of the CF6 / F103 I believe it's entirely a matter of nomenclature.
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