F-35 Joint Strike Fighter News, Videos and pics Thread

TerraN_EmpirE said:

To Err is Human to Arrr is Pirate.

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Jura said:

On the Second Engine (dated 7/08/14 10:00am -- I found it only now -- hope it's not a cross-post):

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Briefly, this would be more competitive than the successful F100/F110 situation. In the prior case, while those two engines were competing to power the same aircraft they weren't really interchangeable. You needed different tools, the maintenance procedures differed and you flew them different, especially because initially the F110 was available with a lot more thrust.

In the case of F135/F136, initially the engines would be more similar to the user community. Maintenance at the unit level would be performed using the same standard tool kit and would be 100% interchangeable in the jet. The F136 even used the same engine transport trailer and dolly. The only thing different for the maintainer would have been the location of the oil tank and some of the borescope plugs. At at the depot that there would be differences in tooling, but since the manufacturers would be running the depots as part of the engine contract anyway, that wasn't a problem.

The plan was that the Pratt engine was a derivative of the F119, so it could be available sooner and wouldn't be a pacing item for the program. Therefore, it was the sole engine specified for Lots 1-5. Starting with Lot 6, IIRC, the buys would be competed. That's one of the reason the cancellation of the F136 was pushed so hard in 2011, it was scheduled to fly in an F-35 later that year I believe.

Pratt would have the advantage of starting earlier, being in production and operational. GE's engine would benefit from being designed around the F-35 (it was not a YF-120 derivative) from the start and could take advantages of developments in the program that occurred in Lightning development. For example, from the very first it could make full use of the increased airflow that could be provided by the revised F-35 intakes. GE was touting its technology as being more advanced, with improvements in fuel burn and durability and potentially more growth.

The idea was that with two companies competing for annual buys for new aircraft as well as replacement engines (hence the requirement for more interchangeability), both would be incentivized to offer the best they could in terms of price and performance.

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Pointblank said:

The thing is, there are plenty of US fighters that have relied on one engine very successfully in the past. The F-4 Phantom II is the best example of this.

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TerraN_EmpirE said:

Jeff based on the Context of the post I don't think he was actually counting the number of engines in the airframe but rather refers to the number of engine options for the Aircraft as a whole. The Navy started the F4 as massive redesign of there F3 Demon (cue the Omen theme) as part of that redesign the Navy tested three engine options then setting on the J79-GE-2. From the moment the J79 was chosen the Super demon and its Phantom II children would always mount two J79 GE series engines.

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