parkzone um trojan wants to stall

[Gary Turner]

Hi guys,

I have a parkzone t28 Trojan ultra micro and even with the battery as far forward as it can be and the c of g where it should be, it still wants to climb steeply unless I use down elavator. Would adding weight and bringing the c of g forward of where it should be help? The elavator is dead level with the sticks at neutral so should I consider trimming it so the elavator points down a little?

Cheers guys

Gary

[Chris Bott - Moderator]

What does the model want to do Gary when you throttle back? If it flies ok on low throttle settings then you might need some down thrust.

[Gary Turner]

Its OK on very low throttle, anything more than 1/2 and it just want to climb.

[Chris Bott - Moderator]

This is normally an indication that you need to add downthrust, i.e. make the motor point downwards a few degrees.

I don't know the model so have no idea if this would be possible, hopefully someone that does will be along.

A couple of other things to check are that the motor mount is nice and solid, so that the motor isn't moving when under power, and that the battery is definately secure enough not to be moving around and changing the C/G.

[Gary Turner]

I did noticed the problem was less noticable in lighter winds so i'm just wondering if I was flying in too strong a wind? never seems to be a calm day these days so ever since I took the hobby back up a month ago all I have done is fly sub 100g ultra micros in winds exceeding 15mph!!!

[NigelH]

Throttle is used to control altitude. I'd expect that the model is set up so that half throttle or so gives level flight and any more makes it climb. Heading into wind is sure to create additional lift.

Those models are not designed for anything more than a breeze although HH will tell you that the AS3X variants can handle more.

[Simon Chaddock]

NigelH

I agree these very light models do not handle turbulence well so are easiest to fly in calm conditions and that they are probably set up to climb at full throttle but does "heading into wind" really give you more lift?

My understanding is that as far as the plane is concened it does not even know the wind is there. Only the pilot notices the change in the speed over the ground.

[John Privett]

Simon, you're absolutely right. The model has no "knowledge" of which way the wind is blowing. It just affects our perception of what is going on.

For instance a model flying at 30mph and climbing at 1 foot per second will appear to us to be climbing more steeply when flying into wind than when flying downwind. This is just because of the angle the flightpath makes with the ground. In the extreme case, when flying into a 30mph headwind it will make no forward progress with respect to the ground, but will be climbing vertically (though the nose will NOT of course be pointing vertically up!)

[Alan Randall]

I had this problem with a Parkzone Micro cub during indoor sessions. On examining a number of cubs in the room, there was varying amounts of down thrust built into them. Some were getting over this by applying a throttle - elevator mix so that as the throttle was opened, down elevator was applied. I took mine apart and applied more down thrust to cure the problem.

[buster prop]

I've got one of these and was out flying it earlier this evening. It's a great little flier within limits, yes it does tend to climb flying into wind although as it's so light I don't fly the T28 in any more than a slight breeze. I think it's because of the undercambered wing section. The T28 doesn't fly inverted very well either, needing lots of down to keep it level. That's also due to the wing section. For batteries I use the Overlander 165mA 26C ones and get 7-8 minutes at full throttle most of the time. I'm amazed at how nimble the little T28 is, love flying it outdoors when it's calm.

[John Hickson]

I found the same thing with my T28, it wanted to go vertical even with the battery as far forward as the foam would allow. I ened up using the 300mA cells I use for my Mcpx, just widened the battery slot a little and changed the battery connector. It balanced fine and I get about 10mins flght time.