56000 lb thrust F136？ 转自aviation week

An interesting snippet about the F136 has long been neglected: a Rolls-Royce statement in 2002 that the engine could generate 56,000 lb. (250 KN) of thrust.

I remember it well because, so far as I know, it was put on record only once, in a July 26, 2002 report that I wrote while working for Reuters. Readers might think the figure is rather high, so I'll set out the circumstances in which it was divulged. You can decide for yourself whether to believe it.

Rolls-Royce made the statement several times at that year's Farnborough air show.

The first time was in a chart that it displayed at a press conference to illustrate its military engines. It showed the F136 at 56,000 lb. I don't think that chart has ever been seen again.

The second statement, and confirmation that this was not a mistake, came a few seconds later. The host of the press conference, the then head of Rolls-Royce's defence aerospace business, Colin Green, pointed to the chart and said: "Here is the F136 engine, which pumps out a whopping 56,000 pounds of thrust."

The Reuters report then recounts: "Green, speaking to reporters and to Reuters in an interview at the Farnborough air show in Britain, said the F136 would have the advantage of lower running costs because, being so powerful, it could deliver adequate thrust without being pushed to its limits.

"'We believe the engine will have lower life-cycle costs,' he said."
Still worried about reporting a mistake, I waited a day to get further confirmation from Rolls-Royce before writing the report. A press officer duly verified and confirmed the figure. There had been no mistake, but the company would make no further comment, she said.

This leaves me wondering how close the F136 could get to 56,000 lb. when installed in an F-35. Does such a thrust require more augmentation than is available from the current afterburner? Are the ducts big enough to feed the engine at anything near that rating?

And was that ultimate rating specified by the Dept. of Defense (which would imply that the F135 can get to 56,000 lb., too) or was it a design choice that GE and R-R made to minimize running costs and provide for future growth?

The latter is more likely. Aviation Week's David Fulghum reports that GE researchers claim the F136 has a bigger core and more potential thrust growth.

We can't reproduce the whole Reuters report here, because we don't own the copyright, and I can't give you link to it, because neither Reuters nor any of its clients put it on a free web site for the general public. For seven years it has been locked up in the World Beyond the Password, which is why few people have heard of Rolls-Royce's interesting revelation.

But I noticed that Ares poster Horde mentioned the 56,000 lb. rating here a few months ago.

Bill Sweetman adds:  Anyone else is free to comment, but I also remember this number being mentioned. However, I think I heard of it earlier, and in a specific context.

Lacking a lift fan, Boeing's JSF was designed around an engine with a higher mass flow and bypass ratio than Lockheed Martin's lift-cruise engine - one way or another, you had to increase mass flow, static thrust and BPR to meet the vertical landing requirement, and Boeing did it with a fixed cycle and LockMart with a dual-cycle system.

The result was that a "Boeing" engine, whether from GE/RR or PW, had both more static non-afterburning thrust and a higher bypass ratio - which meant more fresh air and a potentially higher augmentation ratio. My estimates at the time pointed to 32K versus 26K military power, 400 lb/sec versus 335 lb/sec airflow and 0.8 BPR versus 0.5. So I suspect that the 56K figure was what you could get if you bolted the biggest possible augmentor on the Boeing engine for a 75 per cent augmentation ratio.
                                                                                                       ---- bradley perrettAn interesting snippet about the F136 has long been neglected: a Rolls-Royce statement in 2002 that the engine could generate 56,000 lb. (250 KN) of thrust.

I remember it well because, so far as I know, it was put on record only once, in a July 26, 2002 report that I wrote while working for Reuters. Readers might think the figure is rather high, so I'll set out the circumstances in which it was divulged. You can decide for yourself whether to believe it.

Rolls-Royce made the statement several times at that year's Farnborough air show.

The first time was in a chart that it displayed at a press conference to illustrate its military engines. It showed the F136 at 56,000 lb. I don't think that chart has ever been seen again.

The second statement, and confirmation that this was not a mistake, came a few seconds later. The host of the press conference, the then head of Rolls-Royce's defence aerospace business, Colin Green, pointed to the chart and said: "Here is the F136 engine, which pumps out a whopping 56,000 pounds of thrust."

The Reuters report then recounts: "Green, speaking to reporters and to Reuters in an interview at the Farnborough air show in Britain, said the F136 would have the advantage of lower running costs because, being so powerful, it could deliver adequate thrust without being pushed to its limits.

"'We believe the engine will have lower life-cycle costs,' he said."
Still worried about reporting a mistake, I waited a day to get further confirmation from Rolls-Royce before writing the report. A press officer duly verified and confirmed the figure. There had been no mistake, but the company would make no further comment, she said.

This leaves me wondering how close the F136 could get to 56,000 lb. when installed in an F-35. Does such a thrust require more augmentation than is available from the current afterburner? Are the ducts big enough to feed the engine at anything near that rating?

And was that ultimate rating specified by the Dept. of Defense (which would imply that the F135 can get to 56,000 lb., too) or was it a design choice that GE and R-R made to minimize running costs and provide for future growth?

The latter is more likely. Aviation Week's David Fulghum reports that GE researchers claim the F136 has a bigger core and more potential thrust growth.

We can't reproduce the whole Reuters report here, because we don't own the copyright, and I can't give you link to it, because neither Reuters nor any of its clients put it on a free web site for the general public. For seven years it has been locked up in the World Beyond the Password, which is why few people have heard of Rolls-Royce's interesting revelation.

But I noticed that Ares poster Horde mentioned the 56,000 lb. rating here a few months ago.

Bill Sweetman adds:  Anyone else is free to comment, but I also remember this number being mentioned. However, I think I heard of it earlier, and in a specific context.

Lacking a lift fan, Boeing's JSF was designed around an engine with a higher mass flow and bypass ratio than Lockheed Martin's lift-cruise engine - one way or another, you had to increase mass flow, static thrust and BPR to meet the vertical landing requirement, and Boeing did it with a fixed cycle and LockMart with a dual-cycle system.

The result was that a "Boeing" engine, whether from GE/RR or PW, had both more static non-afterburning thrust and a higher bypass ratio - which meant more fresh air and a potentially higher augmentation ratio. My estimates at the time pointed to 32K versus 26K military power, 400 lb/sec versus 335 lb/sec airflow and 0.8 BPR versus 0.5. So I suspect that the 56K figure was what you could get if you bolted the biggest possible augmentor on the Boeing engine for a 75 per cent augmentation ratio.
                                                                                                       ---- bradley perrett