F-35B will have the most complex single engine for a jet

All about the Pratt & Whitney F135 and the (cancelled) General Electric/Rolls-Royce F136
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neptune

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Unread post31 Dec 2011, 20:28

That_Engine_Guy wrote:
madrat wrote:What's the difference between the F135-PW-100 and F135-PW-400?
..
TEG


LRIP 5 is about $3 million (10%?) difference on each $26 million (approx.) engine, navalized as Teg indicated.

btw, I have yet to locate the type cost for the Navy Dept. LRIP 4 engine purchase contract, if available?? Happy New Year :)
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That_Engine_Guy

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Unread post31 Dec 2011, 20:41

neptune wrote:LRIP 5 is about $3 million (10%?) difference on each $26 million (approx.) engine, navalized as Teg indicated.

When looking at LRIP contracts or engine contracts as a whole don't forget this is not a completely accurate measurement of 'per engine' price...

When you read the contract it states; "This low rate initial production (LRIP) contract includes production, spare parts, sustainment and delivery of [this] lot of F135 engines."

So nobody knows (without seeing the contract's breakout) what 'spare parts, sustainment, and delivery' actually costs?

Ever purchased a spare parts for military jet engines? Tooling/support equipment isn't cheap either.

:cheers: TEG
[Airplanes are] near perfect, all they lack is the ability to forgive.
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Unread post17 Jun 2014, 16:38

Some old words from Bevilaqua about the LiftFan/Engine concept for the F-35B - note the compromises taken overall.
Joint Strike Fighter PERSPECTIVES
Code One Magazine July 1996 Vol. 11 No. 3
Paul Bevilaqua, Lift-Fan System Inventor


Paul Bevilaqua could claim that he has been working on the Marine and Royal Navy variant of the Joint Strike Fighter since 1985, when he began researching short takeoff and vertical landing technologies on a NASA project at the Skunk Works. His subsequent work led to a patent in 1990 for the lift-fan concept used in the Lockheed Martin STOVL variant.

"The goal of those early studies was a supersonic STOVL aircraft," Bevilaqua explains, "but at that point, we were designing airplanes, not inventing propulsion systems. Several companies were conducting similar studies. Everyone was reworking old concepts or looking at new concepts that didn't provide any real advantage. NASA was disappointed in the lack of innovation."

As these studies ended, the Advanced Research Projects Agency asked the Skunk Works if it could come up with any new ideas. "We started from the beginning," Bevilaqua recounts. "First, we looked at all the old ideas that hadn't worked and tried to understand why they hadn't worked. From that study, we made a list of requirements for an ideal supersonic STOVL propulsion system.

"Then we used a variety of brainstorming and creativity exercises to come up with a new concept," Bevilaqua continues. " The technique that worked broke the problem down into its fundamental elements. Since modern fighters have a thrust-to-weight ratio greater than one, the basic problem is to get half of the thrust from the back of the airplane to the front. The simplest solution is to duct it there, but ducting makes the airplane too wide to go supersonic. So we looked for other ways to extract energy from the back, transfer it to the front, and produce lift.

"We generated a lot of wild ideas involving energy beams and superconductivity," Bevilaqua says. "but none worked out until we looked at a variable-pitch turbine to extract power from the jet exhaust. From that point, everything just started falling into place."

From these ARPA studies, the Skunk Works recommended two STOVL approaches: a gas-driven fan and a shaft-driven fan. ARPA liked both of them. "We thought the shaft-driven fan was the better concept," Bevilaqua says. "However, the gas-driven fan was perceived as being less risky. Propulsion engineers are familiar with ducting gases through an airplane. But the idea of shafting 25,000 horsepower was new. People were uncomfortable with the magnitude of the number. But there's really little to fear. The shaft inside a jet engine is already transferring around 75,000 horsepower."

A lift fan concept involves two STOVL-related problems at once. "The lift fan system efficiently transfers thrust from the back of the airplane to the front," Bevilaqua explains. "At the same time, it increases the total thrust of the engine because it increases the bypass ratio from a relatively low one associated with fighter engines to a high one for vertical flight. In other words, it makes the airplane more like a helicopter in the vertical mode.

"The Harrier makes a similar approach," Bevilaqua continues. "It has a large fan to augment the thrust of a small engine core. But the airplane has to live with that fan in the cruise mode. Because the fan is so large, the airplane can't go supersonic.

"Our lift fan approach is like taking that one large fan on the Harrier's engine, breaking it into two smaller fans, and turning off one of the smaller fans when the airplane converts to the cruise mode," he explains. "The concept doesn't compromise the other JSF variants. Our STOVL concept requires twin inlets, what we call bifurcated inlet ducts, to create the space needed for the lift fan. That is the only design requirement. And bifurcated ducts have low-observable and performance advantages that improve all of our JSF variants."

Source: http://www.codeonemagazine.com/images/C ... 8_7528.pdf (13.8Mb)
RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post21 Nov 2014, 02:24

X-35B VLs & LiftFan Development

RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
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Unread post12 Oct 2015, 17:36

Rolls-Royce video for the Rolls-Royce LiftSystem

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