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Old 02-05-2012 | 10:20 AM
  #25  
AeroFinn
 
Joined: Jun 2007
Posts: 328
Received 1 Like on 1 Post
From: Turku, FINLAND
Default RE: Propeller Thrust Estimator


ORIGINAL: pe reivers

Umran,

Can you export the file in XLS format? My software cannot handle XLSM.

For your information: The THP calculator is known to be extremely optimistic. When I use my own calculator, and set the fuselage drag to 3, I get:
19.47 lbs
18.3lbs
16.95lbs and
9.4 lbs
It seems your test rig has slightly lower drag values, so if set to 2.8 my sheet is spot on, except for APC. That is due to APC having very different designs for different prop sizes, so each prop size would need it's own constants.
Hi Pe and others

Thank you for great attempt to create a usefull thrust calculator

What am I doing wrong? Is there some input values I'v missed?

When I try to use your calculator:

Mejzlik 20 X 6 (prop Constant 1,18; RPM 8800; fuselage drag estimator 3; altitude air pressure calculator 100 meters; local air temperature 20deg Celsius)

I get 22,19lbs not 19,47 lbs (ref. what you seem to get) ??

BTW for a Great Planes Yak 54 25%: Is the drag estimator 3 pretty much correct?

Danke viel best regards,

Artto