Author Topic: Hirth F- 23 and F-33  (Read 289 times)

Offline 3D2

  • Jr. Member
  • **
  • Posts: 10
  • Total likes: 0
  • OS:
  • Unknown Unknown
  • Browser:
  • Chrome 90.0.4430.218 Chrome 90.0.4430.218
Hirth F- 23 and F-33
« on: June 14, 2021, 09:08:26 AM »
A question was asked pertaining to performance of 2-cycle engines in another thread...

The Hirth (50 HP) 2-cylinder F-23

With 2.5:1 reduction, on a 485 pound gross RW-2 that I fly which has nothing superfluous-- like a tach, fuel gauge,  or flow meter-- just four temp sensors. Based on average fuel flow of 2.25 US gal per hour, I can work backwards from the chart and throttle position that it's probably turning the 72 inch x 39 pitch Culver prop at 1900 or so rpm at 65 percent or so doing 60 - 65 mph or so according to the strut mounted pressure gauge.

I also fly a Part 103 RW-5 powered by the single cylinder (28 HP) Hirth F-33

With the same 2.5:1 reduction unit on a 315 pound gross weight the average fuel flow is 1.67 US gal per hour. Working backwards from the chart-- because it has just one CHT, one EGT, throttle, choke, and kill switch on it's panel-- and throttle position turning a 56 inch x 30 pitch Culver prop at roughly 1900 or so rpm and 65 percent power doing 50-55 mph or so according to the strut mounted pressure gauge.
--Barb (RW-2 Aviatrix)

 

SimplePortal 2.3.7 © 2008-2021, SimplePortal