Why doesn't F1 use Top Fuel style clutches for launch?

[strad]

the clutch is at about 8minutes 56..I think it was 8:50 something.
https://www.youtube.com/watch?v=-VF0JwxQqcA

[autogyro]

Yeah r-r, got any references to cite - that give cost, serviceability, TBO & etc, facts on that F-35 VTOL?

Are any of them actually operational yet?

Maybe Auto-Gyro will chime in here & opine that the F-35 makes F1 look sensible.. budget-wise..
& T-F present as paragons of well-sorted economical longevity - by comparison

There is plenty of information on the F35 on line J.A.W.
The forward turbine to lift fan system clutch on the aircraft must be one of the most optimistic design challenges of all time.
That it works at all is a small miracle from American money throwing.
I seem to be getting more involved with committee meetings discussing this hopeless aviation project, so I will not go into detail on this thread on clutches.
In very simple terms, the concept for a joint services supersonic, multi roll, VTOL/STOL combat aircraft was known to be a completely flawed concept in the UK in the 1970s, no ifs and no buts.
I am hoping that at the conclusion of various talks, the result will be to bring down the current UK government and show up this government and the previous governments in power during this F35 Lockheed money laundering exercise for the criminally misinformed morons they have been.

[Cold Fussion]

Maybe Auto-Gyro will chime in here & opine that the F-35 makes F1 look sensible.. budget-wise..

To be fair, pretty much everything looks sensible next to the F-35 program.

[bdr529]

the clutch is at about 8minutes 56..I think it was 8:50 something.
https://www.youtube.com/watch?v=-VF0JwxQqcA

I posted that video on page 2. It's my go to video when explaining top fuel drag cars to non-drag racing fans.

I did make my yearly visit to the drag races this summer to see this car from my younger days

[strad]

sorry didn't see that it was the same one...I thought you had only posted a shorter version ... goin senile I guess.

[riff_raff]

Yeah r-r, got any references to cite - that give cost, serviceability, TBO & etc, facts on that F-35 VTOL?

Are any of them actually operational yet?

Maybe Auto-Gyro will chime in here & opine that the F-35 makes F1 look sensible.. budget-wise..
& T-F present as paragons of well-sorted economical longevity - by comparison

The air-cooled carbon-carbon clutch used to drive the lift fan on the F-35B has been operational for quite a while now.

http://www.jsf.mil/images/gallery/sdd/f ... 35_008.jpg

It transfers close to 30,000hp from the power turbine to the counter-rotating lift fan. The clutch assy weighs a couple hundred pounds, but it is designed to bring the lift fan from a standstill to a speed in excess of 10,000rpm. The clutch assy is qualified for over 400 engagement cycles. Far more impressive than any TF or F1 clutch.

The F-35B clutch and lift fan was designed by the Indianapolis Allison division of R-R. Contrary to what autogyro claims, the shaft-driven lift fan used on the F-35B is by far the most efficient STOVL system ever employed, and it works very well.

http://upload.wikimedia.org/wikipedia/c ... LHD_1).jpg

[autogyro]

Hi riff raff, like to explain why the F35B is limited to 9 VTOL operations before engine rebuild?

[Brian Coat]

http://sbirsource.com/grantiq#/topics/86523

[riff_raff]

Hi riff raff, like to explain why the F35B is limited to 9 VTOL operations before engine rebuild?

The F-35B is a STOVL aircraft that rarely performs a vertical TO. It mostly performs a short TO when carrying a payload, and performs a vertical landing after deploying the payload and expending most of its fuel.

The F135 engine used on the F-35B does not require an overhaul after just 9 vertical landings. In fact the main reason the F-35B uses a shaft driven lift fan is because it is far more efficient at producing lift than the ducted compressor air system used by the Rolls-Royce Pegasus engine on the Harrier. The Pegasus engine needed to use compressor water injection to keep the engine from overheating when performing a vertical landing, and there was only enough water supply for about 90 seconds of vertical flight during a landing.

I know some of the engineers at Allison/R-R that worked on the F-35B clutch and lift fan design. The clutch has been qual tested for 2X the 400 engagement cycles required by the model spec. And so has the F135 engine power turbine and drivetrain connected to it.

[PlatinumZealot]

Hi riff raff, like to explain why the F35B is limited to 9 VTOL operations before engine rebuild?

The F-35B is a STOVL aircraft that rarely performs a vertical TO. It mostly performs a short TO when carrying a payload, and performs a vertical landing after deploying the payload and expending most of its fuel.

The F135 engine used on the F-35B does not require an overhaul after just 9 vertical landings. In fact the main reason the F-35B uses a shaft driven lift fan is because it is far more efficient at producing lift than the ducted compressor air system used by the Rolls-Royce Pegasus engine on the Harrier. The Pegasus engine needed to use compressor water injection to keep the engine from overheating when performing a vertical landing, and there was only enough water supply for about 90 seconds of vertical flight during a landing.

I know some of the engineers at Allison/R-R that worked on the F-35B clutch and lift fan design. The clutch has been qual tested for 2X the 400 engagement cycles required by the model spec. And so has the F135 engine power turbine and drivetrain connected to it.

Riff_raff. I have always wondered. why didn't they use carbon fibre for the drive shaft tube and housing? To save weight I thought they would have implemented more composites in that area.

[autogyro]

Riff_raff. I have always wondered. why didn't they use carbon fibre for the drive shaft tube and housing? To save weight I thought they would have implemented more composites in that area.

There would be absolutely no point.
The weight and volume of the lift system on the F35B defines the aircraft's performance as well below that of any conventional fixed wing types it may face in combat.
There is no point in further reducing the already minimal reliability of the clutch and drive system for the fan by trying to lose small amounts of weight.

[gruntguru]

Riff_raff. I have always wondered. why didn't they use carbon fibre for the drive shaft tube and housing? To save weight I thought they would have implemented more composites in that area.

If those components are steel alloys there would be considerable weight saving in a carbon fibre alternative as you say. Performance benefit/Cost ratio is always a factor. Torsional rigidity is another - driveshafts are often designed torsionally soft (quill shaft) to absorb torsional vibrations. The smaller diameter steel shaft would be better suited for quill shaft design.

[riff_raff]

Riff_raff. I have always wondered. why didn't they use carbon fibre for the drive shaft tube and housing? To save weight I thought they would have implemented more composites in that area.

PZ- The F-35B does use a composite driveshaft to power the lift fan.

[J.A.W.]

As A-G wrote,
- the concern re aero/drag of a - dimensionally/bodily larger- carbon composite shaft - is not applicable F-35-wise..

[PlatinumZealot]

Riff_raff. I have always wondered. why didn't they use carbon fibre for the drive shaft tube and housing? To save weight I thought they would have implemented more composites in that area.

If those components are steel alloys there would be considerable weight saving in a carbon fibre alternative as you say. Performance benefit/Cost ratio is always a factor. Torsional rigidity is another - driveshafts are often designed torsionally soft (quill shaft) to absorb torsional vibrations. The smaller diameter steel shaft would be better suited for quill shaft design.

I guess, you will get a bigger Diameter with carbon fiber driveshafts. Even if it's lighter weight, it will hurt aerodynamics.

With the steel driveshafts, load application is also a lot easier.

I know a challenge with Carbon fibre driveshafts had always been the interface of the spline which is steel to the actual composite, but that problem had been solved so the diamater is pretty much the same as steel ones. One disadvantage that I know still remains is that if the shaft has to be regularly checked for any damage.