Basic

[sweetpea]

Short answers........Yes, bisect middle of upline.

No.......do not do a second trim pass, your wasting everyone's time if you do.

[excelpoint]

Rusty It will be nicer if you intersect the middle of the upline. You can do another trim pass if you feel you have to but generally you just do a turn around manouver and start again.Not a big deal if you do do another pass. Just remember time can be of the essence especially at Bendigo with so many pilots flying.

[RustyTumbles]

Cool, thanks guys.

I just thought if your plane was slightly out of trim that you would have to fly both rounds like that, if you weren't allowed to re-trim. I realise time is a huge factor at big comps, if it was me I'd probably got run with it instead of holding everyone up..

[excelpoint]

Rusty, normal procedure is:
Take off into wind, procedure turn or reverse cuban etc back onto your line downwind, turn around manouver of some sort, the level out and call in the box, you can do another upwind trim pass if you need to but most guys dont. You really shoudnt need to trim your plane anyway. The free pass is more just to get your line sorted out, once you have finished your first sequence then you woulkd normally do a turnaround manouver at the down wind end then back into the box to start your next sequence.

[RustyTumbles]

Thats what I'll practice doing so I get the hang of it. Fingers crossed everything will go well with the ultimate and I will be able to get plenty of practice for bendigo. I'm really looking forward to my first comp, and I guess I'm going to stand out with probably the only bipe there.

[RCFlyer55]

Practicing on the sim is hard because of the field of view for me. Placement I find really hard. But it will have to do until it warms up a bit.

[lazyboyflyer]

At Phoenix, we exited figure 9 at the middle of the verticle line, just the way it looks on the aresti.

[RustyTumbles]

Hey guys,

I took the ultimate out again today to run it through some more trimming. However I'm a little confused about what to do with my simptoms. I am using the peter goldsmith trimming guide to IMAC. No in his article he says to get the CG right first, however I think I may have two problems giving me fast indications as to what to change. (hope that mad sense).

Ok if I put the plane on a 45 degree upline and roll inverted it will climb gently at full throttle. However if I enter the line at half throttle and do a half roll, it climbs aggresively. Also if you roll inverted on the 45 upline of a half reverse cuban at full throttle and pull the power to pull around the 5/8 inside loop. It climbs aggressively again if you do pull the elevator as you reduce the power. I am thinking along the lines that A) the model is still to tail heavy, and B) the engine is making upthrust. Am I on the right track here?? I don't want to make the wrong changes. Please let me know your thoughts on this..

Cheers

Rusty

[towball]

	Quote: Originally Posted by RustyTumbles
	Hey guys, I took the ultimate out again today to run it through some more trimming. However I'm a little confused about what to do with my simptoms. I am using the peter goldsmith trimming guide to IMAC. No in his article he says to get the CG right first, however I think I may have two problems giving me fast indications as to what to change. (hope that mad sense). Ok if I put the plane on a 45 degree upline and roll inverted it will climb gently at full throttle. However if I enter the line at half throttle and do a half roll, it climbs aggresively. Also if you roll inverted on the 45 upline of a half reverse cuban at full throttle and pull the power to pull around the 5/8 inside loop. It climbs aggressively again if you do pull the elevator as you reduce the power. I am thinking along the lines that A) the model is still to tail heavy, and B) the engine is making upthrust. Am I on the right track here?? I don't want to make the wrong changes. Please let me know your thoughts on this.. Cheers Rusty

You must set the C of G at the manufacturers recommendation to start with.. Do some basic tests to determine that the C of G is right. Dont be on the tail heavy side for IMAC..
The plane must be zero trimmed. That is not carrying any trims on any surfaces. Fly along with the wind in your face or on the back of your head and pull a number of verticals, if the plane is zero trimmed and the plane goes to the wheels then add some upthrust or if the plane goes to the canopy add some downthrust. Then check vertical down and if the plane moves off the down line with zero trim then you may have an incidence problem.. Once you have this right then fly into the wind over your head and away from yourself and pull a number of verticals to check the right thrust..
It is important that you fix one thing at a time.. not all at once..

Towball

[notorious_benny]

Rusty, it sounds more like a thrust line issue. If you have the model balanced a little nose heavy then it is time to look at thrust line.

Another way to check up or down thrust is to as towball say's get you c o g correrct first. Then trim the plane so that it is straight and level at full power.

FLy at full power straight and level, then chop the throttle (Dont touch elevator). If the plane ubruptly climbs, then you have too much down thrust. If it ubruptly pitches nose down then you have too much up thrust.

You have it close when you can chop the throttle and the plane continues in its path. Of course it will slowly start descending.

Once you get it close, retrim the model and then start doing vertical lines like Towball says to do. If you have done the straight and level technique you will not have to chase it too far as it should be getting pretty close. But pulling those vertical line will allow you to fine tune it if neccesary.

[excelpoint]

Sounds like you may still be tail heavey Rusty. Do as Baz said once you have your CG sorted.

[notorious_benny]

Oh, dont forget to retrim for full power everytime you make a thrustline adjustment.

[RustyTumbles]

How do I get zero trim?? I am carrying some down trim as is at full power. Is that a thrust issue? Or do I adjust my elevators to where they are now with the matchbox with the trim centred? I still think it is a touch tail heavy becuase the elevator is very touchy. Also the fire wall is built with right thrust only and no down thrust. So at the moment there is no down thrust on the motor. Should I add some or try and get the CG right first. It is just hard to tell what going on when I roll inverted as it goes crazy with little power but is reasonable with full power....

[excelpoint]

Rusty how far awy are you from the factory CG?

[rcdart]

Rusty, I think if you are carrying down trim at full power, and your CG is close to factory, what happens when you pull power off, does it climb? If so put some down thrust. Or put that sucker in the car and come for a drive, Ill fix it for you on saturday, you can make it from Richmond to here in about 10 hours