Go Back   Knife Edge > RealFlight - Designer's Corner > RealFlight G3 - Designer's Corner
Use of this site is subject to our Terms of Use. | Looking for technical support? Read this!

Thread Tools Rate Thread Display Modes
Old 01-14-2007, 10:13 PM
tlgibson97's Avatar
tlgibson97 tlgibson97 is offline
Registered User
Join Date: Feb 2006
Posts: 40
help with creating an engine.

I'm trying to set up a torque curve for an OS 91fx. they dont have any information except for a range of rpm's with differnet props. Is there a way to set up an engine in G3 with only this information. Meaning can I derive a torque value from the rpm with a certain prop. Any help is appreciated. Thanks
Reply With Quote
Old 01-14-2007, 11:18 PM
CanCanCase's Avatar
CanCanCase CanCanCase is offline
Registered User
Join Date: Sep 2006
Location: North Bend (NOT Bend), Oregon
Posts: 229
If there's a howto on creating engines, curves, etc. I can't find it. (Adding recorded audio of the engine IRL would be great too!)

Maybe OpJose will chime in here with a few "Click me!" and "Me too!" lines to point us in the right direction? If there isn't anything handy that's relevant, maybe someone will bribe him to write up some directions to get where we want to go?

Seems engines are a hot topic this week... keep digging in the other engine related threads too. An answer may pop up in one of them soon...

NO ADVERTISING ALLOWED! (But you can ask me what I do...)
Reply With Quote
Old 01-14-2007, 11:20 PM
opjose's Avatar
opjose opjose is offline
Registered User
Join Date: Nov 2005
Location: Third rocky planet.
Posts: 13,220
Well when I lack other info here is what I do.

Look up the recommended prop and the power output in BHP of the engine.

This info is available on the standard info sheets for the engine.

You'll also find the RPM at which this output is measured and weight of the engine.

Remember that this is an expression of power on an UNLOADED engine in flight (e.g. decending in a dive).

Now I take a similiar engine in G3 and look at the torque values to determine approximately the torque figure should be at a given RPM...

e.g. 210oz/in, etc.

I then create the new engine with a 10 point curve and set this value at the highest point of the curve with everything else curving up to this point realistically.
This is saved with a new name.

I then set up G3 to have the recommended blade/prop size using my new engine.

I then fly the plane straight up and watch the power output maximums in the Navguide, both loaded and unloaded.

I then re-adjust the engine until I get about 70%-80% of the stated max bHP as a MAXIMUM instantanous power output in G3. This max should only occur briefly and only under certain conditions.

Finally I adjust the curve so that the engine cannot rev faster than the real thing.

e.g. if the O.S. 91 limits out at 13000RPM I set this to about 180oz/in and then 14000RPM to ZERO.

My numbers are no where near exact, I'm just using them to illustrate the process.

That's it. This will not be too far off!
Newbies please click here for important instructions about forum posts: CLICK ME!
Reply With Quote

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT -4. The time now is 09:19 PM.