Thread: Supersonic

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I was just going trough a thread from another site (don't worry, my loyalty is here). A question was brought up about the counter throws on a crankshaft going supersonic and at what rpm it takes to achive the FPS to get it to that point. I chuckled when I read it because the issue of the whole mass was not considered. Back in the Eighties, we sat around one Friday evening and pondered this situation and discussed what effects it would have on the reciprocating assembly inside the crankcase. We did a lot of geometrical computations and we discovered that some engines could achieve supersonic vortex and some where not affected at all. Question is, At what RPM can you achieve the critical cross over point to meet the requirements of supersonic stall/vortex inside your crankcase. Just food for thought and silly wondering. P.S. we figured it out and it was just a time killer for us.

I don't think there's much worry about the counterweights going supersonic. If we use a diameter of 8", then the circumference that the tip of a weight describes is 25". At 10,000 rpm's, the tip travels 250,000"/min. This equals 20,833 feet per minute, 3.945 miles per minute and 236 miles per hour. Since the speed of sound is 761.2 mph @ 15* Celcius @ sea level, the same crank would have to spin to 32,250 rpm's to reach mach 1.

Originally Posted by techinspector1

I don't think there's much worry about the counterweights going supersonic. If we use a diameter of 8", then the circumference that the tip of a weight describes is 25". At 10,000 rpm's, the tip travels 250,000"/min. This equals 20,833 feet per minute, 3.945 miles per minute and 236 miles per hour. Since the speed of sound is 761.2 mph @ 15* Celcius @ sea level, the same crank would have to spin to 32,250 rpm's to reach mach 1.

Somehow I just don't think that is possible, but Scooter might prove us wrong.

Originally Posted by NTFDAY

Somehow I just don't think that is possible, but Scooter might prove us wrong.

I remember something about 4000 feet per second on the velocity of the pistons being a limiting factor after that is reached things break quickly.
I dunno?

Don't worry, we got the right guy on the job.


Don

Originally Posted by Itoldyouso

Don't worry, we got the right guy on the job.


Don

Why it's Super Scooter!

It's a bird, It's a plane....No, it's Super Scooter!

Well Scooter are you the right man for the job or do we have to bring on the "Super Squirrel"??