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trimming question
Hi
I have a Spark that flies just great but have one problem. the Cg is set around ~25-27% depending wich battery I put in , mixing is at minimum , some trothel to elevator some rudder to aileron and a smal mix from rudder to elevator. In the trialgel in P13 I have some problems the first leg (that I think its normal) it need to be held so it not dive, the second its up to me to fliy it nice but the last leg it pitches upwards I tried yesterday to let go off the elvator to see if I put in some but still it climbed before and after the roll. Is it my CG that are to much forward, I have moved the battery a bit forward and backward but no big re****. The indience og stab is 0 as it should be the wing is about 0.5 positive and thrustline are set to get it to go straight in the uplines. |
RE: trimming question
I think its a CG issue, but still check the below links to setup a pattern plane.
http://www.mat.uc.pt/~pedro/ncientif...s/trimming.txt http://www.horizonhobby.com/article/...-pattern-plane |
RE: trimming question
I'd be dialing 1-800-ASK-BRYAN</p> |
RE: trimming question
I have done some thinking...I maybe have to much positive incidence on the wing, think I have to check that tomorrow morning before going to the field. it had a smal tendence to go to canopy in the verticals today , finaly I got one flight with no wind at the end off the day ...This trimming is always big thinking...I could give Bryan a call but I'm in Norway long distance and think it will be expensive!
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RE: trimming question
If it goes to the canopy in the verticals, and you're happy with the downthrust, you should increase the wing incidence slightly, not decrease it?
I always think of the "Effective" elevator position, when working out pitch problems. If you have too little incidence on the wing, you'll need a bit of up elevator trim to fly level,in level flight, to balance the downward pull of gravity. This same up elevator trim, will cause a slight pitch to the canopy, when going vertical,because the pull of gravity is now effectively parallel to the fuselage,rather than at right angles to it. |
RE: trimming question
I think I have some checking to do!! the postiv pitching I have in the 45 degreds up its not much but its to much to just let it fly by itself..
check tomoroow morning and se what to try! but I see your point it easy to think opposite some times! |
RE: trimming question
If you think the CG is correct, easy to check by rolling inverted and seeing how much you need to push to keep it inverted. If the CG is right and still pulling to the canopy on up lines, you need more down thrust. I also fly a spark and noticed it required a good amount of down thrust. The nose has no down thrust build in, so you need to start there. Again my spark needed more downthrust as I was not able to adjust the wing due to lack of wing adjusters. once you added the downthrust; if it is still doing this add a little more. Once you get it right check your 45's and see if you plane deviates. Good luck
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RE: trimming question
+1 Bill Clark!
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RE: trimming question
ORIGINAL: Rune Hi I have a Spark that flies just great but have one problem. the Cg is set around ~25-27% depending wich battery I put in , mixing is at minimum , some trothel to elevator some rudder to aileron and a smal mix from rudder to elevator. In the trialgel in P13 I have some problems the first leg (that I think its normal) it need to be held so it not dive, the second its up to me to fliy it nice but the last leg it pitches upwards I tried yesterday to let go off the elvator to see if I put in some but still it climbed before and after the roll. Is it my CG that are to much forward, I have moved the battery a bit forward and backward but no big re****. The indience og stab is 0 as it should be the wing is about 0.5 positive and thrustline are set to get it to go straight in the uplines. Regards, Jason. |
RE: trimming question
Rune PM Me with your set up" accurately measured" , the mix you are running and exactly where the c/g is set I`ll help you figure it out
Bryan |
RE: trimming question
Well thanks for input all off you!
I soon leaving for a 1,5 drive to get to a airport (our club has no flying on monday) so will check the wing incidence now befor I go . Nats i Norway start on thursday so have not much time to sort it out and do not want to do any really big change befor that as it is not that bad, but it is just that "smal thing" thats not right, and have now around 200 flights on the plane and havent had that many good days off trimming weather lot off wind and turbulence. So I get back to you after this day , if weather is playing on my side think it going to get some rain at the end off the day! |
RE: trimming question
Back home from the field, added ca 0,5 deegred incidience and problemwas alomst gone, tried several triangel loops and decided to add just a turn more on the adjuster so I think without messuring I now have ~1 positive on the wing.
So then we let all be like this so far. |
RE: trimming question
What 1 deg positive are you Crazy:D
Just saying.. Bryan |
RE: trimming question
ORIGINAL: Rune Back home from the field, added ca 0,5 deegred incidience and problemwas alomst gone, tried several triangel loops and decided to add just a turn more on the adjuster so I think without messuring I now have ~1 positive on the wing. So then we let all be like this so far. |
RE: trimming question
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RE: trimming question
Dick told me that for the last 15 years :)
Bryan |
RE: trimming question
ORIGINAL: Bill Clark I'd be dialing 1-800-ASK-BRYAN</p> |
RE: trimming question
<blockquote class="quote">quote: ORIGINAL: Bill Clark I'd be dialing 1-800-ASK-BRYAN</p> </blockquote> LMAO http://images.rcuniverse.com/forum/image/s2.gif <span class="info"></span> _____________________________ Dick told me that for the last 15 years http://images.rcuniverse.com/forum/image/s45.gif Bryan <span class="info"></span> |
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