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Old Jul 25, 2011, 09:14 PM
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Thrust angle would be my guess as well.

Pat
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Old Jul 25, 2011, 10:01 PM
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Ahh yes… the old thrust angle in the shoe trick. Researched a bit about it and I guess there are tests I can do to see if it is off. If it is, I guess the way to fix it is by putting a washer or two between the top engine screws and the firewall? This way I can drop the engine a bit right??
Old Jul 25, 2011, 10:08 PM
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Yes, that's what you want to do.

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Old Jul 25, 2011, 11:10 PM
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Quote:
Originally Posted by Vlodek9 View Post
Ahh yes… the old thrust angle in the shoe trick. Researched a bit about it and I guess there are tests I can do to see if it is off. If it is, I guess the way to fix it is by putting a washer or two between the top engine screws and the firewall? This way I can drop the engine a bit right??

I think you want to drop it down and to the right....at least that's what someone told me about the P-38. But maybe that's something to do with multi engine planes??
Old Jul 25, 2011, 11:20 PM
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From what I read that is the standard trust angle down and to the right. In my case it is not pulling to the right or left just up, so I’m thinking just down. But next time I fly it I will do some tests that I read about on the net regarding this issue and we will see.
Thanks everyone for your help.
Rob
Old Jul 26, 2011, 12:18 AM
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More down, no right and maybe nose heavy too.
IMO, do NOT mix down elevator to throttle as some may suggest. Think about it. Coming in for a landing at 10 over stall speed. Coming up a bit short or going long and only 5' off the runway so you throttle up as it goes INTO the runway.

Rick (i don't like mixes)
Old Jul 26, 2011, 10:33 AM
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One thing I don’t understand about this. Other then the battery and prop, I didn’t change anything. The prop size is still in the manufacturer’s recommendation even for a 3s. And since this is an ARF the firewall is already adjusted for the correct thrust angle. So why would the trust angle have to be changed/adjusted for a 4s battery?
Maybe it is just nose heavy, but then why don’t I see or feel it at cruise speed when I trim it?
Guess I’ll find out this Sunday if the weather permits it.

P.S.
Why do we say its nose heavy if the nose goes up? I read and understand the physics behind it so I’m not actually asking. Just making a point that it sounds backwards.
Old Jul 26, 2011, 10:41 AM
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Because you are blowing a LOT more air OVER the top of the wing which generates a lot more lift.

If it is nose heavy you have up elevator dialed in to maintain level flight. Increase RPM and more air goes over the elevator which is already up some so that makes it climb more at WOT...

Rick (NOT an engineer so take this with a grain of salt)
Last edited by rampman; Jul 26, 2011 at 12:14 PM. Reason: Changed to ---> so after name
Old Jul 26, 2011, 11:16 AM
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Rob,

Other Rick is absolutely correct. As your prop spins faster due to the higher cell count the airflow over your wing also increases(relative wind). This creates more lift and your airplane goes up. Now if your airplane isn't just climbing, but also pitching up then you may also have a thrust angle problem.

Other Rick
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Old Jul 26, 2011, 12:11 PM
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You guys are the best bunch of non engineers I've ever met. One of you needs to write a RC book for dummies. Even I understand the content.

Non engineer.
Horrible pilot.
The one the only JEREMY
Old Jul 26, 2011, 07:35 PM
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I agree with Rick agreeing with the other Rick, who is not always very agreable.
Old Jul 26, 2011, 08:25 PM
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Quote:
Originally Posted by swarick View Post
Aeronautical Engineering Degree
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OK Mr. Smarty Pants... answer me this one: If I have a plane on a giant treadmill.......

Or how about this.... is a 50CC Composite ARF louder at 6:00AM than at 10:00 AM?? I think noise travels better in the thin air!?!
Old Jul 26, 2011, 10:00 PM
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Actually noise travels better in thick air. That's why no one can hear you scream in the vacuum of space.

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Old Jul 26, 2011, 10:02 PM
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Originally Posted by chalmrast View Post
OK Mr. Smarty Pants... answer me this one: If I have a plane on a giant treadmill.......

Or how about this.... is a 50CC Composite ARF louder at 6:00AM than at 10:00 AM?? I think noise travels better in the thin air!?!
He wouldn't know that one, he wasn't there!

Pat
Old Jul 26, 2011, 10:04 PM
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Actually noise travels better in thick air. That's why no one can hear you scream in the vacuum of space.

Other Rick
And it travels even better under water!