On Mon, 17 May 2010 09:35:06 +0100, stuart noble
wrote the following:

John Rumm wrote:
On 16/05/2010 17:09, js.b1 wrote:
On May 16, 4:42 pm, stuart wrote:
John Rumm wrote:
Multiply by the blade circumference... so for a 190mm blade at 4500 rpm
that is 4500 x 0.19 x pi = 2686 m/sec

Heh-heh, blade tip travelling at beyond even rail gun projectile
hypersonic speed would be fun.

I knew I could count on you :-)

RPS = 4500rpm / 60 = 75
Circumference is 2*Pi*R = 2 * 3.14 * 0.19/2 = 0.59m
Circumferential speed = 75 * 0.49 = 44m/sec.

Well what's a factor of 60 between friends ;-)

Yup, my bad - sorry!

What an old boss of mine would term a "slip-up" rather than a mistake :-)

Murphy Math.

--
Facts are stubborn things; and whatever may be our wishes, our
inclinations, or the dictates of our passion, they cannot alter
the state of facts and evidence. -- John Adams, December 1770
'Argument in Defense of the Soldiers in the Boston Massacre Trials'