Reduced throttle pitches up. Why?
 

I have a H9 Edge 540 with a BME 44 pulling it. I am having problem with the plane pitching up and stalling each time I throttle down. During my approch for landing, at idle, the plane noses up and then stalls. I trashed 3 propellers in the 3 times I tried to fly and land it. What should I do to correct this problem? The CG is right where the manual says. I noticed that this plane have a significant right thrust set on the firewall but I don't think this have anything to do with it.
Any info is appreciated.

Reduced throttle pitches up. Why?
 

Sounds like it may be too much down thrust. The engine is pulling the plane's nose down, you compensate with up trim, then when the power is chopped the up trim causes the plane to pitch up. Another possibility is that you have significant down trim, the propwash has a significant impact on the trim, you chop the throttle and the lack of airflow over the elevator causes the plane to pitch up.

Reduced throttle pitches up. Why?
 

Sport Pilot is right on the button, too much down thrust.

Reduced throttle pitches up. Why?
 

Fortunately this is simple to fix by shimming your engine mount.

Reduced throttle pitches up. Why?
 

after you have taken a degree or 2 out of your mount and it still wants to stall then add a little more nose weight or move the CG forward a small amount you may be just a touch tail heavy

Reduced throttle pitches up. Why?
 

It's also possible you're WAY tailheavy... and that in flight you're compensating with elevator, the effect of which is amplified by high thrust.

How violent is the pitch up? Can you control idle pitch with servo trim alone?

Reduced throttle pitches up. Why?
 

try covering your hinge gaps had a 39% AW extra that liked doing that

Reduced throttle pitches up. Why?
 

I would recommend that you check your CG. You could be tail heavy. Since this is an ARF, I will ASSUME that you assembled it correctly so that the CG is the only variable that could be an issue. Make it nose heavy if you have to then try it again!

Reduced throttle pitches up. Why?
 

Thought he said the CG was spot on? I think he is looking for other possibilities. Why state the obvious?

Reduced throttle pitches up. Why?
 

Most kits give you about 1 inch area in your CG range, if he has set it for the back of the CG then he is most likely tail heavy. When I set mine, its always AT THE FRONT SIDE of the CG setting, that way the plane will want to glide and not stall out if you lose a motor and have to dead stick.

Reduced throttle pitches up. Why?
 

Check your ailerons make sure there centered

Reduced throttle pitches up. Why?
 

RE-RE measure your CG. Make sure you're at CG and measure from plan's stated point.

If all this checks out I'd have to say either your control surface is airfoiling somehow or your thrust line's off....

Reduced throttle pitches up. Why?
 

Hi Crow. Does it do it only when landing? How about at altitude? What I'm getting at is sometimes we inadvertantly hold some back pressure on that stick in anticipation of touchdown, especially with a new plane. Also check your radio for forgotten mixing from a previous program. :)

Reduced throttle pitches up. Why?
 

Thanks, Guys,
I finally repaired the damage and made changes based on your recommendations. I move the CG to the most forward location based on the manual (it was on the middle). Shimmed my engine with 2 washers stacked together (about 3/16th thick). Checked all the control surfaces for warp.
This problem happens even at altitude. As soon as I cut the throttle, the plane pitches up then stalls.
I'll keep my toes crossed (can't let go of the stick :-) you know)

Reduced throttle pitches up. Why?
 

You shimmed the engine. How?

Sounds like you have too much down-thrust.

Have you checked the engine thrustline vs. the wing / stab incidence?

Reduced throttle pitches up. Why?
 

How does the plane fly inverted? Chop the throttle when inverted and see what happens.

Reduced throttle pitches up. Why?
 

By changing two things (CG + Downthrust) maybe we will never know...but I'd like to!

You guys remember the CG test while flying? Diving at 45 degrees at full power and chop throttle and watch what happens...if the nose pulls UP you are nose heavy and if the nose pitches down you are tail heavy....right????

Jerry

Balanced right on the recommended point.
 

I had a friend who balanced the completed airplane very carefully at the recommended CG. Then he proceeded to fly the airplane with the cowl off (he was dialing in the engine). The cowl on a 120 size Edge weighs maybe 6 ounces? Boy was that sucker tail heavy without the cowl! Besides being very sensitive to elevator input, it did just what yours does when you chop the throttle.

Jim

Reduced throttle pitches up. Why?
 

I have to agree with the CG as being the problem. I flew my H9 Edge the first time this past weekend with almost identical symptoms. What was also obvious was the tail seemed to be dragging while in level flight. Even though I had the CG set at the middle of the recommended range, I went ahead and moved the 1600mah battery pack forward about 6 inches. When I flew it again it was a different plane. Much more managable and a whole lot easier to land.