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Discussion Starter · #1 ·
when the H2 was launched it was widely rumoured that the chirping noise was due to the tips of the supercharger breaking the sound barrier, something that Spitfires had trouble with at the end of their development with the tips of the propeller doing the same thing and causing handling problems and shake.
My question that is far to complicated for me is either, How big a diameter would the supercharger compresser wheel need to be to suffer this problem at the standard red line ? or how many RPM would the compresser wheel need to do using the standard diameter to really break the sound barrier ?

Yes I'm aware that the noise is in reality a valve blowing off unwanted boost pressure on a closed throttle.

Do we have a mathematical genius on this site ? And just for the record its maths not math !
 

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I did the math before. Tip speed at engine redline is about 460 m/s. Speed of sound at standard ambient conditions is about 340 m/s. The local speed of sound at the tips will be a bit higher because the compression raises the temperature. But it's beyond mach 1 even accounting for that.
 

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Discussion Starter · #3 ·
I did the math before. Tip speed at engine redline is about 460 m/s. Speed of sound at standard ambient conditions is about 340 m/s. The local speed of sound at the tips will be a bit higher because the compression raises the temperature. But it's beyond mach 1 even accounting for that.
That really is amazing , over 100 m/s faster than Mach 1 .
I take it that due to the small diameter of the compressor wheel and what must be perfect balance there are no adverse side effects of the tips breaking the sound barrier ?
Great mathSSSSSS ;)
 

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Doing the sums in old money.....Imperial instead of metric. Lets remember all uk parts of Concorde were built in inches and the French pats in metric.

Using whole integers the diameter of the turbine as 2 inches and Pi as 3 and the step up as 10 (9.18) ....


At 10,000 rpm thee outer part of the rotor is travelling 600,000 inches per minute. 36,000,000 inches per hour.

A mile has 1760 yards X 36 inches = 63,360 inches. round this down to 60,000

knock 4 0000's of both numbers to get 3,600 divided by 6 = 600 mph.
 

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Discussion Starter · #6 ·
Doing the sums in old money.....Imperial instead of metric. Lets remember all uk parts of Concorde were built in inches and the French pats in metric.

Using whole integers the diameter of the turbine as 2 inches and Pi as 3 and the step up as 10 (9.18) ....


At 10,000 rpm thee outer part of the rotor is travelling 600,000 inches per minute. 36,000,000 inches per hour.

A mile has 1760 yards X 36 inches = 63,360 inches. round this down to 60,000

knock 4 0000's of both numbers to get 3,600 divided by 6 = 600 mph.
Now I'm in a dilemma trying to work out if you're a genius or an idiot !
Not sure about the Concorde Imperial/ Metric story but sound feasible , I do remember something like a NASA / British Aerospace collaboration with one working in U.S. Gallons and one in Imperial Gallons and a satellite or probe missing its orbit by tens of thousands of miles .
Anyone who hasn't made a mistake hasn't made anything , the key is not doing it twice .
 

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OK WHY!!! some very cleaver Japanese engineers, builders, designers, marketers, sales people bla bla..... put this incredible reliable machine together, who cares how fast the supercharger goes.. it TWITTERS so enjoy
 

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OK WHY!!! some very cleaver Japanese engineers, builders, designers, marketers, sales people bla bla..... put this incredible reliable machine together, who cares how fast the supercharger goes.. it TWITTERS so enjoy

WHY ??? Because they could!!!!

I hope my bikes not twittering. #getthisidiotoffme .

Maybe the marketing campaign should have been,,,,," If you have to ask why you maybe aren't ready."
 

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now now throttle X supercharges 1000cc goes like ****.. you do not need to be a mathamatishion or very bright to figure that out!!
 

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^^^^^ I remember a fresh crate lump being lowered in the bay with a guy stood on it.^^^^^^ Some can talk it , others walk it.
 
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