Zpat

My Feedback: (2)

OK Guys,
I posted this in the 3D forum with no results. Maybe someone here can answer.
I'm trying to harrier this Su-Do-Khoi.
I finally got a harrier but the transition from flying on the wing to hovering on the prop is really sensitive. Every time I point the nose up it goes up and I have a hard time throttling it to go into a harrier and it takes a lot of room and time to get it to do it. I'd like to enter a hover just above the ground and the only way to do it would be out of a harrier.
Do you think moving the CG further aft will do anything? How much aft do you guys go at a time.
There is a lot of throttling to go into a harrier. I tried to do it like the 35 and 40 percenters do ( pop the nose up and add throttle) It does'nt work that way for me.
The wing still does a lot of rocking just before it starts to Harrier.
Any ideas?

hoverit-RCU

Where is the CG now?

Zpat

My Feedback: (2)

The CG is 6" aft of the wing leading edge. This is the aft limit on the plans.

travis newman

i agree its a cg problem.get the cg as far back un till u dont like the way it flys.ther is a verry fine line ther,sort of a sweet spot for the pefect cg.also you MUST have no less than 50 degrees throw on elivater with almost 100% exponential rates.i can do a loop from take off as soon as the plane leaves the ground strait into a hover one foot off the ground.also i can do a tail slide to a tail landing from 50 feet high.to do an[ elivater ]move its like the hairier bu the angle of the plane is only ,whell almost horisonal to the ground and it gust comes strait doun with no forword movement.it helps to have about a 8 mph brees for this moove.not to brag hear but just to show what u can do with the proper 3D CG. teirs some golden rules to go by hear.

1] A moter like mvvs.40 for best throtle transition and POWER! ot pull out of a hover .
2] A popeller like apc 11/4 or no more than 5 pitch.
3] Max throws on all serfaces with plenty of Expo rates
4]and last but not least a CG 1/3 back from wings leading edge or further!!! All theis factors are a MUST, leave one out and u wont be doin 3D. hope this helps ya man.

Zpat

My Feedback: (2)

I have the largest servo arms the fuselage will accomodate and only have 40 degrees elevator travel , how did you get 50 percent? I'm running a MVVS .77 and have plenty of power. my CG is farther than a 1/3 back from the leading edge. It sounds like finding the sweet spot involves pushing the CG back until it snaps out. I'm not into rebuilding.

Billy Hell

My Feedback: (2)

I find my CG by rolling it inverted. It it flies straight then the CG is good. No up and no down.

Blackhawk3D

A .77 on a .40 size plane? You can hover that thing with a .46.

Texas 3D

My Feedback: (16)

First make sure that the Travel adjustment on your radio is maxed out. This is in order so the servo can travel it's maximum amount. Then, make also sure the elevator will be able to travel more then 40 degrees. Maybe the elevator is hitting the horizontal stab at 40 degrees and doesn't allow more travel. If that is the case you will have to bevel the stab or elevator.
Moving the CG back isn't really that hard. Always try to avoid adding dead weight and only do so if nothing inside the wing can be moved further back. Move the CG by a 1/4" at the time to see where the right CG is for your flying style.
To stop the wing rocking, mix some spoilerons (up elevator up ailerons and vice versa) in your radio. Start with a 70% and give it a try. This takes away lift, and should stop the rocking. If not, then simply adjust the mixing. Maybe it's only 60% or maybe 80%. It is different with every plane.
The engine you are using is also a very heavy engine and to powerful for this plane. That might also be the reason you are having trouble with the climbing. I would consider a engine swap to something smaller if you have. Weight is the worst enemy of 3D planes. A good and strong 40 size engine will work just fine.

Zpat

My Feedback: (2)

This is a 60 size airplane. I'll try some of Texas 3D suggestions.
Thanks for the input.

PaulSwany

My Feedback: (45)

This is the 60 Size SuDoKhoi?... I was about to give you a hard time for your engine choice.... But that should work on the .60 size SuDoKhoi. I have a Super Tiger .90 on mine... As far as elevator travel, you're 40 degrees should be enough. I don't have to give full elevator to mine to get it to harrier and I have around 45 degrees of travel.

Besides an aft CG... you might want to look at what prop your using. Getting the plane to harrier is a combination of elevator and throttle untill you find the sweet spot. I like a 14 x 6 on my .90. You might try a 13 x 6 or a 14 x 4w on yours. Make sure your throttle transition is really clean and be ready to jump on the power if it starts to fall out. Mine will wing rock sometimes, but some opposite aileron will usually cancel it out after a few rocks.

My cg is set to just aft of the main spar. takes just a touch of down elevator inverted. I usually set mine up like Billy.... Trim to hands off upright, then roll inverted and see how much down elevator it takes to maintain level flight. Too much and I move the CG back. If it climbs, I move it foward.

Texas 3D

My Feedback: (16)

Also didn't know that it was .60 size. Engine shold be OK then.
Let us know what mods you did, and how she flies. Good luck.

Zpat

My Feedback: (2)

I'm going to try Billy's suggestion to determine the CG. I want to thank you guys for the info. I've got this airplane doing everything I want except for tail on the ground hover.
Happy Flying!