From: Andrew Martin <andrew@martinag.com.au>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sat, September 25, 2010 10:56:16 AM
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