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Pratt & Whitney hopes to beat price goals for F-35 engine  (Source: DefenseNews)
Company found a way to boost thrust by 100 pounds for Marine F-35

The F-35 fighter program is over budget and behind schedule, but the contractors are working hard to get back cut costs and adhere to time schedules. One of the most costly components of the F-35 is its engine made by Pratt & Whitney. The company has announced that it is working to lower the price of the engine and that the price could drop even more in the coming years. 

This news comes ahead of the start of negotiations between the Pentagon and primary contractor Lockheed Martin for the next batch of fighters. Bennett Croswell, president of Pratt & Whitney military engines said, "We have activities planned and in place to bring the cost down in [low-rate initial production] 5."

The fifth batch of F-35 fighters is part of the LRIP 5 batch. Pratt & Whitney has plans to reduce the cost of the F135 engine to the price of the older F119 engine that the F-22A uses. What exactly those prices are is unknown since that is proprietary information owned by the engine builder. Pratt & Whitney has said that it was able to beat the price target during the negotiations for the fourth batch of fighters and it hoped to be able to beat pricing again on the fifth batch purchase.

Croswell said, "We're constantly looking at ways to do even better than what that plan is."

While negotiations are going on for the next batch of engines, Pratt & Whitney has announced that it has found a way to increase the thrust of the F135 engine used in the vertically landing version of the F-35 that will be flown by the Marine Corps. The change will add 100 pounds of thrust to the engine and the company is also trying to reduce the weight of the engine by 100 pounds.

There are some in Washington that want to see development of the second F-35 engine renewed. An amendment proposed by the House would allow the second engine to be developed at the cost of the builder. The second engine for the F-35 was officially killed in March.



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RE: why the big deal?
By Mudhen6 on 6/8/2011 2:40:26 AM , Rating: 2
The rated output of the engine means nothing - e.g. 43 000lb of thrust is a useless figure. The actual output of a turbofan engine is highly dependent on external factors like speed and altitude.

For example, the Dash 229 engines in the F-15/16 are rated at 29 000lbs of thrust, but can probably produce anywhere from 3000lb of thrust to 40 000 of thrust at max output, depending on the amount of air its sucking in.

Lower speed = less airflow = less thrust from an air-breathing engine.

Higher altitude = less oxygen = also less thrust. Of course, air density has an inverse relationship to altitude, but a positive relationship with drag (i.e. flying at low altitudes/higher air densities generates more drag from the airframe). Drag also increases exponentially with increasing speed.

It is for these reasons (and more) that every single airframe/engine combination has a "sweetspot" in terms of the various aspects of performance. For example, the term "corner speed" is used to describe the "sweetspot" of the flight envelope that generates the highest sustained rate-of-turn within the smallest turn radius.

This is also the reason why fanboi arguments are bull***t. Sure, a MiG-29 may have the highest possible turn rate, but that kind of performance can only be attained at its sweetspot. IRL you can pretty much guarantee that (trained) enemy pilots will do their best to not fight in that particular part of the flight envelope, and instead try to suck the MiG-29 pilot into fighting in their sweetspot.

Back on topic, regarding the F-35 - the extra "100 lbs" of thrust is probably most welcome, in addition with shaving off 100lbs from the weight. Consider that Lockheed Martin started using thinner metal skins (IIRC) in order to make ends meet like a year or two ago.

Obviously, every little bit counts.


RE: why the big deal?
By Mudhen6 on 6/8/2011 3:07:51 AM , Rating: 2
What I meant to say was "irrelevant," not useless. The published output figures do give readers a rough idea of how powerful turbofans are relative to each other, although I honestly don't know how the published numbers are arrived at and whether it's standardized across the industry (I'm guessing yes, at a specific "speed," level flight at sea level).

Turbofan output changes dynamically across an aircraft's flight envelope, so trying to attribute a single figure to thrust (e.g. 43 000lb) is usually an exercise in irrelevance.


RE: why the big deal?
By sorry dog on 6/8/2011 3:56:04 PM , Rating: 2
The 100lbs is probably a typo.

What P&W is doing is allowing the engine computer to temporarily boost power with more fuel. The downside is hotter turbine temps which means less time between overhauls. They claim they have tested the motor at the higher temps and it passes durability tests, but it's sure to raise the operating cost of that type as the engine computer will surely ask for maintenance more often.

...but that is definitely going to cheaper than a whole nother engine program.

...but won't matter if the B model get canceled ... which will mean a large amount of the design compromises will have been for nothing.

The F35 will be a kick ass jet, but it could have been better. I think it's obvious now that the costs would be much better if the B model had nothing to do with the A/C models...enough so that the marine plane could be a separate contract and program and still been cheaper.


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