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-   -   P Factor and engine offset (https://www.rcuniverse.com/forum/3d-flying-82/6131188-p-factor-engine-offset.html)

haasjj 07-19-2007 12:54 PM

P Factor and engine offset
 
How much offset will i need for a Seagull Harrier 3D using a Evolution 100 engine? Will it work if I put a washer behind the engine mount on the left side between the mount and firewall. Is the left side correct? Please help!!!:):)

warhwk 07-19-2007 02:00 PM

RE: P Factor and engine offset
 
Right Thrust is dependant on several things. 2 degrees is good starting point.
Some people are such good flyers that they can correct in any flight attitude with rudder and use no engine offset.



But if you don't know what to look for, how will you ever know it is correct for YOUR plane? See http://www.rcaerobats.net/trim_chart.htm

FlooredCOBRA 07-19-2007 02:23 PM

RE: P Factor and engine offset
 
I would of thought the Harrier would of had built in right thrust already. But to add yes washers work perfectly behind engine mount. to measure use a protractor and you should be good to go. Here is a link to a paper protractor to print out. Works good to tape to plane- http://www.ossmann.com/protractor/co...protractor.pdf

haasjj 07-19-2007 02:42 PM

RE: P Factor and engine offset
 
Thank you both VERY MUCH for your help!! I don't know if the Harrier has built in right thrust or not, but i didn't use the kit engine mount. I bought a Du-Bro engine mount and had to drill it out to mount the engine my holes were probably off a slight bit, I had them as close as possible but 2deg is not much to the human eye. So if i was off 2 deg in the wrong direction that would have made the total correction I need about 4 deg, I'll try a washer then check until I get it right. Thanks again.

broke_n_bummin 07-20-2007 02:19 PM

RE: P Factor and engine offset
 
True 3D and pattern planes don't have right or downthrust. Try to hover with right or down thrust. Even with a gyro, the plane will still drift. A HAKE to the left would be easier than the right. Even a regular knife edge would be difficult to pull off. Besides, the P factor with say a X4W or X6W prop isn't near as bad as a 6 or 8. It just gets some getting used to...

Jack Hyde 07-21-2007 04:31 PM

RE: P Factor and engine offset
 
I don't know about pattern planes but nearly all of the TRUE 3d planes I have seen or heard of have right thrust. You can hover fine without it, you just have to hold some right rudder in while you do it. That is just harder to do. I hear Chip Hyde uses no right thrust but programs right rudder to throttle mixing. Paul Swanson recommends 3 degrees right on Mojos of all sizes. UCD's come with 3 deg rt thrust built in, as do most ARFs. I have tried it all and now have 3 deg right thrust in all of my planes.

broke_n_bummin 07-21-2007 09:43 PM

RE: P Factor and engine offset
 


ORIGINAL: Jack Hyde

I don't know about pattern planes but nearly all of the TRUE 3d planes I have seen or heard of have right thrust. You can hover fine without it, you just have to hold some right rudder in while you do it. That is just harder to do. I hear Chip Hyde uses no right thrust but programs right rudder to throttle mixing. Paul Swanson recommends 3 degrees right on Mojos of all sizes. UCD's come with 3 deg rt thrust built in, as do most ARFs. I have tried it all and now have 3 deg right thrust in all of my planes.
Hmmmmm .... that's odd ... my Goldberg Edge and G P UCD have 0 degree thrust "built in" and both of them are ARFs. I had a Radio City Typhoon that also had no built in thrust angle.

Jack Hyde 07-22-2007 07:29 AM

RE: P Factor and engine offset
 
The firewall on my UCD 46 is attached with 3 deg right slant relative to the fuse. I thought they were all made that way.


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