Speechless... there really is an "11"

pilotbraden wrote: This shows the basic principle of the Allison turboshaft engine. Replace the propeller with a rear differential and drive your car. This system can have significant lag. There also are constant speed turboprops that spin at a very narrow rpm range. These respond to power changes by increasing or decreasing the propeller blade angle to maintain set rpm. These have fantastic throttle response, but would be harder to use in a car.

Turn that entire Allsion around 180* and eliminate the reverse flow intake & that's pretty much exactly how a GE-T-58 chopper engine works works. It's been forty years since I played with them, but as I remember the compressor side ran about 65,000-70,000 rpm. And the free-spinning output turbine ran around 12,500 rpm & made 1,500 hp. The total package weighed about 350 pounds. The power to weight ratio is great but as Keith Tanner and others pointed out, you now have two turbos to lag and lots of over-run.

It would take hellish strong brakes and a very quick adapting (reverse sprag?) freewheeling clutch to keep the output shaft cranking at 12,500 during braking and "part throttle" time. Then hook the clutch output shaft through a 2-1 constant ratio gearbox to the CVT @6,200 rpm to make the power package useable.

Again, I agree with Keith. This would make an awesome roundy-round set-up. But it doesn't seem practical on a road course. In either case, in today's tightly controlled racing world, if everyone else doesn't have one you probably can't race one either. So much for "racing improves the breed."

Keith Tanner wrote: Poor throttle response.

That's it. You had to use the throttle preemptively - stopping and going. Ed Lowther, as I recall, discovered that at Daytona 24-Hours in 1968 by not shutting the throttle off soon enough and hitting the wall in this same car. It also crashed at Le Mans that year.

I operate turbine engines for a living flying a King Air C90GT. The only way they would work real well is if you could keep the engine spooled up the whole time and adjust power through the clutch instead of the throttle.

They work better in land speed racers and off shore power boats IMO.

Did any of you actually read the berkeleying article or any of the wikipedia information about it? No? Go do it now.