Nose pitch's up

[Tired Old Man]

If it pitches with throttle changes it's thrust line. Throw all the mixes and c/g changes you want at it but the engine thrust line will still be impacting the flight. That's whay so many of you IMAC flyers have all that right thrust, correct? BTW, I have a 35% Edge and it does not change AOA one iota with throttle changes.

[Edgeman 540]

	Quote: Originally Posted by Tired Old Man
	If it pitches with throttle changes it's thrust line. Throw all the mixes and c/g changes you want at it but the engine thrust line will still be impacting the flight. That's whay so many of you IMAC flyers have all that right thrust, correct? BTW, I have a 35% Edge and it does not change AOA one iota with throttle changes.

Old Man does it sound like it has too much up thrust?

[astrohog]

I am certainly no guru here, but I own and fly both the 30% and the 36% Edge's and neither one of them have ever had this issue. Neither of my Edge's have any right, up or down thrust added in nor was it ever suggested in any of the build manuals. I have recently added a little rudder-to-throttle mix on my 30% er as it does want to pull left on uplines.

I would suggest double-checking how your motor is mounted and make sure it is done per the PAU manual (perhaps adding a little right thrust if you prefer). Also, double-check that your CG is within the PAU recommended range. Both of my planes do all the 3D maneuvers well ( I only know this as the club "pro's" have done em all with my planes ) and they are set up bone-stock per the PAU instructions.

As far as the torque roll issue: I am not very good at torque rolls, but I do know that when I get either of my PAU Edge's locked-in to a hover, it is near impossible to STOP the torque roll!!

Again, the best advice I can give is to re-check the CG, thrust line, incidences up/down thrust and right/left thrust and make sure they are all per the build manual.

I can imagine how frustrated you must be! Keep us posted as to your findings. I hope you get your issues sorted out so you can enjoy your Edge as much as I do mine!!

Regards,

Astrohog

[Edgeman 540]

Thanks Astrohog.

[Tired Old Man]

If a plane pitches up when you back off the throttle you have too much down thrust.

[JoeAirPort]

That's what I'm thinking too. I had this plane for three years. It didn't do this. If it's really tail heavy it might baloon on landing but it won't pitch up when you chop the throttle. If it pitches up when you chop throttle add more up thrust. That's how I remember it. The reason is that because the engine is pulling it down when it's rev'ing, and the elevator trim is pulling up to compensate, and keep it straight and level. When you chop the throttle and lose the engine thrust pulling it down, the elevator trim pulls it up.

[Chris Puckett]

I should have said that I only experienced this during landing. Not something I ever noticed in flight with throttle changes.

[jack01]

This may be a little repetitive, but here's how I trim out a new airplane:

First off, you have to remember that in aerodynamics everything is a balancing act. There is no free lunch. Weight balances lift, thrust balances drag, and so forth. When you change one, you directly affect another and indirectly affect something else. One apparent problem can actually be something else all together. When trimming an airplane, you've got to remember that it will likely take several flights and some trial and error to get it dialed in. Even after that, you'll probably be tweaking it for a while. Remember, if you make a change in any of the below steps, start over from #2.

1. Set all of the incidences per the manual. On most monowing giant scale airplanes, this will mean everything is set to zero. Typically, the top of the motor box is leveled, and then everything else is leveled based on that. Right thrust is typically 2.5 degrees.

2. Take off, and trim the airplane for straight and level at 50% throttle. Wind makes this tricky, so if it's windy/bumpy, try to pull an average.

3. Roll the airplane inverted with the throttle still at 50%. It should dive slightly. By slightly, I mean you shouldn't be able to fly an entire upwind/downwind leg without a noticeable pitch change, but it shouldn't try to do a loop either... 2-3 clicks of down elevator trim should make it fly level. If it stays level or climbs, you're tailheavy and vice versa.

4. Roll upright. Then pull the throttle to idle, and watch what happens. If it dives immediately, you probably have too much upthrust. If it climbs, you probably have too much downthrust. Just make sure to quickly figure out what it's doing, because after the speed changes much, you're looking at a CG issue rather than a thrust one. That's why noseheavy airplanes dive on landing, and tailheavy airplanes balloon.

5. If you've trimmed the airplane properly so far, you should be very close to where you need to be. Everything else is fine tuning. Try some downlines and see what it does. 90 and 45 degree downlines are pretty good at showing CG issues. If it pitches up, you've got some uptrim to compensate for being noseheavy. If it pitches down, you've got downtrim because it's tailheavy.

6. Now try some uplines. You should try these from a full throttle pass and a smooth, but firm, pull. Make sure you are truly wings level when you pull. Watch what the airplane does after pitching up to 90 degrees. From here, you should be able to fine tune your thrust line. If you find yourself doing a lot of IMAC style flying with multiple vertical snaps, your speed will probably try to bleed off during the upline. In that case, you may need more right thrust than normal. Just remember, as your speed builds again, the plane will now try to go right.


If you need to change your thrustline just a little bit, I usually use washers made out of Coke cans. For example, if you need downthrust and rightthrust, add two washers behind the mounting lug on the top left, and one washer each on the top right and bottom left. That will make sure the engine is making even contact all the way around.


Remember, a properly designed, built, and trimmed airplane requires very few if any mixes. It's like a computer radio. If you took the time to properly setup your servos mechanically, your subtrims and travel adjustments should all be pretty darn close to even. IMHO, all the mixes in the world are no substitute for learning how to fly the airplane.

[cjcyclesrc]

Good Info Jack.



On the CG topic, I have found a Yak to fly straight and level inverted with a neutral CG. I'm guessing it's due to the symmetry to the airframe. Other airframes require a slight push inverted.

[Tired Old Man]

Pitching up on landing is when most will immediately notice a down thrust issue. A little bit too much either way can be hard to see higher up. Cut the throttle, pitch up, add throttle and pitch down. Makes for some interesting landings. Good way to have a prop strike or two. Balance is exibited more with changes in elevator deflections. Tail heavy and each change is more than the last. Nose heavy and you can't hold the nose up for the flair as well as you think it could. Also makes for long low level flight just above the runway trying to bleed off speed for the touchdown.

[Edgeman 540]

Thanks guys for taking the time to share all of this info. We still have 15mph winds here so the next day that it's more calm I'll be taking it out.
I'll post here what fixes the problem.

[scott m lyons]

	Quote: Originally Posted by Tired Old Man
	Pitching up on landing is when most will immediately notice a down thrust issue. A little bit too much either way can be hard to see higher up. Cut the throttle, pitch up, add throttle and pitch down. Makes for some interesting landings. Good way to have a prop strike or two. Balance is exibited more with changes in elevator deflections. Tail heavy and each change is more than the last. Nose heavy and you can't hold the nose up for the falir as well as you think it could. Also makes for long low level flight just above the runway trying to bleed off speed for the touchdown.

See the last sentance that is the 40%.Hows the hatch does it fit?