South Korea resets Fighter Jet bidding

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XanderCrews

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Unread post26 Jul 2020, 16:55

blindpilot wrote:
jessmo112 wrote:... baffles me that other plane makers would let the U.S. corner the market like this.


Nothing baffling about it. This is the other side of the "death spiral." It's happened before. The old English Electric Lightning ("one") was probably the best fighter of it's era. But once the F-104 and Mig 21 gathered momentum the battle was over. Costs plummeted, support/logistics infrastructure exploded and everyone would either have the F-104 or a Mig 21.

Instead of the death spiral of decreasing numbers exploding costs, you have what I call the Black Hole spiral. Once enough mass is gained it just sucks in every thing around it. Interesting that Lockheed got it twice however.

MHO,
BP



Thats really well described.
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jessmo112

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Unread post26 Jul 2020, 20:57

And thats another thing. Someone mentioned in this forum Chinese engineering. But where is the Mig-21 equivalent?
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steve2267

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Unread post27 Jul 2020, 14:55

FWIW...

(and costs not withstanding...)

The X-35 flew with a modified F-100 motor, but with a F-119 fan, if memory serves. It may be possible to dust off some of the old F-16 development designs to which John Will once alluded... Take an F-16, give it the twin vertical tails, switch to a bifurcated inlet, prolly need to stretch the sucker a bit, plop in the Allison-designed lift fan... no internal carriage of weps, but may as well make the FLIR / laser designator internal (or not, to save $$). Two wing stations for gas & bombs, one wing station for missiles, and wingtip missile station.

Wallah, an F-1365... for all the lesser nations. May not have the Viper get-up-and-go, but...
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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f119doctor

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Unread post27 Jul 2020, 15:32

X-35 was powered by a modified F119 engine, with a larger fan and a 2 stage low pressure turbine. Basically the same general layout as the F135. The X-32 was the same, except the fan was even larger (higher airflow) to support the direct lift STOVL configuration. No F100 engine parts or components were involved.
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steve2267

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Unread post27 Jul 2020, 16:32

I stand corrected.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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steve2267

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Unread post27 Jul 2020, 16:52

I confused the X-35 with the powered lift demonstration that was carried out in the 1994-95 time frame. From Dr. Bevilaqua's Genesis of the F-35 Joint Strike Fighter paper:

The demonstrator propulsion system was built and tested to address these concerns and prove the feasibility of the dual-cycle engine and drive system. The demonstrator engine and lift fan were constructed, like a hot rod, with components from existing engines. The first-stage fan and inlet guide vanes from the Pratt & Whitney YF119 engine were used for the lift fan. This fan ran at the same power level as one stage of the production lift fan, so that the loading on the drive gears was the same as in the production gearbox. The demonstrator engine was assembled by joining the fan and core of the relatively-low-bypass-ratio P&W F100-PW-220 engine to the turbine section from the higher-bypass-ratio F100-PW-229 engine. This bigger turbine could provide enough power to drive the lift fan as well as the engine fan. Two holes were cut in the engine case so that the bypass air could be diverted to the pair of roll control jets, and the engine fan rotor was modified so that the driveshaft could be attached.A variable-area thrust-deflecting nozzle was mounted at the rear of the engine, and the digital engine control software was modified to run in both cruise and STOVL cycles.

In December 1994, the assembled lift fan, gearbox, and driveshaft were demonstrated at the Allison facility in Indianapolis, Indiana. The power transmission losses in the gear set were measured, and operation of the lubrication and oil cooling system in the vertical position were demonstrated. The distortion limits of the fan were established and the ability of the inlet guide vanes to modulate the fan thrust was shown. The success of these demonstrations showed the feasibility of building a flight-weight lift fan and gearbox for the required power levels.

The lift fan was then shipped to the P&W facility in West Palm Beach, Florida. During February 1995, it was connected to the demonstrator engine and operated in both cruise and STOVL cycles, which demonstrated that an engine turbine could be switched from providing jet thrust to providing shaft power to run the lift fan. The ability to rapidly transfer thrust back and forth from the cruise engine to the lift fan to provide pitch control was also shown.

When these tests were complete, the propulsion system was installed in a full-size airframe model made of fiberglass and steel. This model is shown in Fig. 16. This model was mounted in the outdoor hover test facility at the NASA Ames Research Center. The jet-induced downloads out of ground effect were measured to be less than 3% of the jet thrust, and the jet fountain and lift improvement devices were shown to be successful in limiting the induced downloads to less than 7% at wheel height. These are very low numbers. No hot-gas ingestion was detected over a wide range of pitch and roll angles while the aircraft model was suspended 1 ft off the ground.

The transition characteristics of the model were then measured in the NASA 80  120 ftwind tunnel. Drag polars obtained for a range of flap angles and tunnel speeds were used to show that the aircraft could take off and land on a Wasp-class assault carrier with a 20 kt wind over the deck without using a catapult or arresting gear and that it would have a wide corridor for transition from hover to wingborne flight. Measurements also showed that there was sufficient control power for acceleration and deceleration during transition and for yaw control in crosswinds up to 20 kt. This technology maturation program [12,13] demonstrated the feasibility of the dual-cycle lift fan propulsion system and reduced risk to Technology Readiness Level 5.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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f119doctor

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Unread post27 Jul 2020, 18:56

Even the authoritative sources don’t get it 100% right:

The demonstrator engine was assembled by joining the fan and core of the relatively-low-bypass-ratio P&W F100-PW-220 engine to the turbine section from the higher-bypass-ratio F100-PW-229 engine.

The F100-220 engine has a bypass ratio of approximately 0.7, while the -229 is lower at around 0.4. However, the 229 LPT is designed for higher airflow, inlet temperature, and horsepower extraction, making it suitable for the lift fan demonstration.

Interesting that if you add the -229 Fan to this -220 core /-229 LPT combination, you get what is known as a -220P, which had a
thrust rating of approx 27,000 lbs in AB. P&W tried to sell a flow down plan to the USAF where where -229s would be upgraded to -232 configuration with new Fans and LPTs, while the removed existing-229 Fans /LPTs would upgrade the -220 fleet to the -220P configuration. This proposal never went anywhere in the mid 1990s.
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jessmo112

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Unread post27 Jul 2020, 22:32

Ignore last post. I got all mixed up
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