Mailing List flyrotary@lancaironline.net Message #52231
From: Bill Bradburry <bbradburry@bellsouth.net>
Subject: RE: [FlyRotary] simple dyno
Date: Sat, 25 Sep 2010 14:05:38 -0400
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>

Over my head!

A 75 inch log that is 5 inches square swinging at 7000 rpm???  If 191 HP can do that I will be surprised, but would not want to be close enough to witness it!  [:<O

 

Bill B

 


From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Andrew Martin
Sent: Saturday, September 25, 2010 11:56 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] simple dyno

 

Whilst researching propellers, I came across this gem of info from www.jcpropellerdesign.com


Gustave Eiffel (1832-1923) came up with a simple solution for measuring HP without complex apparatus, By using a balanced wood bar instead of a propeller with a square cross section of 1/15th of the length of the bar, you can measure the rpm and calculate the HP available.

Power in HP = 0.0532 (diameter/450)5 (RPM/1000)3

 

As I need a load on the engine when I run it I’m going to give this a go, 1350 x 90mm at 7000 rpm will give me 191hp, that’ll do if I can get it.
--
Regards

Andrew Martin
Renesis RD1c

West Australia

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