Lots of downtrim,GP Eagle
03-01-2004, 08:52 PM
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Lots of downtrim,GP Eagle
Hey all,
Just got a couple flights on my GP Christen Eagle... Flies wonderfull,no pitch roll coupling in K edge,Great scary snaps!!! The DA 50 pulls it with authority!!The one thing is I need almost full downtrim to fly level..
Does this seem like downthrust or insidence or CG issue?
Thanks for your help!!
Frank
Just got a couple flights on my GP Christen Eagle... Flies wonderfull,no pitch roll coupling in K edge,Great scary snaps!!! The DA 50 pulls it with authority!!The one thing is I need almost full downtrim to fly level..
Does this seem like downthrust or insidence or CG issue?
Thanks for your help!!
Frank
03-01-2004, 08:58 PM
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RE: Lots of downtrim,GP Eagle
Does the amount of trim change with throttle setting, if so then up/down thrust is needed. If not, then readjust your trim to the new setting and enjoy.
03-01-2004, 09:50 PM
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RE: Lots of downtrim,GP Eagle
Possible CG problem... roll it inverted. Does it now need a lot of trim the other way? If yes... its CG too far aft.
The power test... may or may not pin it down to thrustline... stay9ing upright, level and adding power adds airspeed so you can end up correcting an incidence problem with thrustline. (which is not good.)
www.nsrca.org has a complete trimming chart. follow the chart and it will tell you whats going on for sure.
Of course... note that the chart is designed for the full symetrical 0-0-0 pattern designs. The Eagle is not one of those designs... so the dive test may be flawed. If the plane has "decalage" it will pull up. If the wings are not symetrical... it will pull up.
The power test... may or may not pin it down to thrustline... stay9ing upright, level and adding power adds airspeed so you can end up correcting an incidence problem with thrustline. (which is not good.)
www.nsrca.org has a complete trimming chart. follow the chart and it will tell you whats going on for sure.
Of course... note that the chart is designed for the full symetrical 0-0-0 pattern designs. The Eagle is not one of those designs... so the dive test may be flawed. If the plane has "decalage" it will pull up. If the wings are not symetrical... it will pull up.
03-01-2004, 11:16 PM
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RE: Lots of downtrim,GP Eagle
The main problem right now is on my last landing I clipped the right wing panel(bottom) from a great crosswind and it broke next to the fuse..[:@] Seems a little weak to me,balsa rear spars,hardwood mains though.. So it'll be alittle while before I get it up again...
Anyway thanks for all the info...
Frank
Anyway thanks for all the info...
Frank
03-02-2004, 12:52 AM
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RE: Lots of downtrim,GP Eagle
Reading this post as have the same problem with a small Ultimate bipe,40 size.Flys with noticable down elevator to fly hands off.below 1/2 throttle tail starts to drop.Need to add more down elevator when landing then Let up on control and tail drops makes nice looking 3 point landings.Seems to fly OK inverted have only flown it a few times moves so quick is hard to tell how stable it is.Used to my Tracker radio and this one has a PCM so can't fly it with the radio so have no ability to easily change settings like flying with everything on high rate.I know I could take wing off and reset everything but trying to avoid that.Don't know where the CG should be but over wide range on top wing always drops nose so assume not tail heavy.Any ideas would be appreciatted.Thanks!
03-02-2004, 03:23 AM
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RE: Lots of downtrim,GP Eagle
I refer you to the same trim chart... at www.nsrca.org
The Ultimate bipes are closer to the 0-0-0 setup... so the chart should be very accurate for you.
Often people like the Ultimates with a bit of a further aft CG than the chart will want... because they are flown 3D instead of Pattern style. (though all the more rearward CG helps with is hanging on the prop and flat spins.... and then spin recovery can be a beast if the CG is too far back and you go dead-stick.) I'll bet you got it set up for 3D and the CG is as far back as you will EVER want it.
The Ultimate bipes are closer to the 0-0-0 setup... so the chart should be very accurate for you.
Often people like the Ultimates with a bit of a further aft CG than the chart will want... because they are flown 3D instead of Pattern style. (though all the more rearward CG helps with is hanging on the prop and flat spins.... and then spin recovery can be a beast if the CG is too far back and you go dead-stick.) I'll bet you got it set up for 3D and the CG is as far back as you will EVER want it.
03-02-2004, 09:38 AM
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RE: Lots of downtrim,GP Eagle
Hi; Thanks for the info!Thats a great site lot of other information I can benefit from.I only fly it as a sport plane but will move the CG forward.Engine looks to be mounted quite far back in the nose.Must be an old plane as uses the system where the engine is mounted to couple plates and they are bolted to hardwood mounts.Front is all balsa too not plastic like nowdays.Calls it a mini ultimate.Has gold stripped decals onthe sides and across the upper wing.Can move the engine ahead an inch on themounts only need couple more holes will try that.May change receivers so can use the computer radio with its wider range of adjustements.Again Thanks.
