I posted before in another thread about prop sizes that my new xtra easy arf keeps wanting to climb...
it was suggested that I add some downthrust but after looking at the engine/mount/firewall I've noticed it already has a TON of downthrust added... The firewall sets at about a 80 degree angle if the nose were 0 degrees and the tail were 180 degrees.....

So here is what I ask, I used to have an old us aircore knighthawk that had flaps, whenever you kicked in the flaps it would nose up and climb....

I've looked at my ailerons and noticed that centered they both are down like flaps by maybe a 1/16th of an inch at the very trailing edge... If I were to adjust them to where they were say 1/16th of an inch up, both sides would this help?

In order for it to fly level you have to have full down trim and about 15 points down trim in the comp radio (jr XF421ex)??

Or would this be a bad idea? Thanks!

First thing I would do is fly it with the ailerons set to level, and see what that gets you. Clevis adjustment should allow for this, or if not, install new pushrods. For sure, you will find the model climbs less, or maybe not at all.

If it does still climb with downtrim on elevator, then you can try setting ailerons to a slight uptrim (maybe 1/16").

What trainer is this? How are your wings mounted (rubber bands or bolted)? Another fix might be to put in a bit of negative incidence (lift the wing trailing edge with 1/16" shim). Any possibility you have down-warp in the trailing edges?

Obviously you want to trim the wing so that your elevator trim is neutral for level flight.

10 degrees of downthrust?! and still climbing??!! Sounds to me like this model needs to be wrung out by a competent instructor.

Is the plane balanced properly? If your tail heavy it'll cause it to climb. Is your wing & tail incidence correct? If not, that can cause it to climb. You need to have someone experienced check your plane out.

99GT
On the two Xtra Easy's that fly at our field, we have found that they needed a 1/16" shim under the trailing edge of the wing.

Set the ailerons level with the trailing edge ane fly it. If it still climbs put a 1/16" balsa shim under the trailing edge and fly it.

After you find out how many shims are needed just glue them in place. I shouldn't take more than two.

Let us know how it comes out.
DEG

yeah its an extra easy....
flew it again today but was in high wind so trim really didn't matter.....
think I might try the shims under the T/E...
wings aren't warped, checked that....
the mds 40 is finally starting to run decent so it has plenty of power, even in high wind I found myself flying it at 1/4 or less throttle...
now that I got the idle fixed this thing will float so slow!
I hovered it down on one landing with a headwind! : )

Did you check what the elevator looks like with the trim adjusted for level flight? Try and hold the plane so that the tail is level as in normal flight and see if the elevator is level with the trim adjusted. Then move the trim back to centre and see if the elevator is up about 1/8" with centre trim. I would give the elevator more down by adjusting the clevice 3 turns by which ever direction you need to turn the clevice to lower the elevator. 3 turns will be enough to see a change in flight characxteristics but not too much that the plane will be radically different and scare you. The amount of change may not even be visible but the plane will notice it and fly accordingly. Test fly and go 1 more trim either up or down until the plane will fly level with the trim at centre. It may take a few flights to get it right but once you have it you don't need model memory for the trim.

If you have a slab elevator and not airfoiled, you can remove the clevis from the control horn. Take two sticks and place one below and one above the stab. Rubber bad bot ends so that the elevator is held in line with the horizontal stab. Do this for both sides to see if there is any twist or un-parallel construction. If everything checks out, then while clamped, connect the control rod and servo with the TX and RX power on. Your true neutral condition now exists.

99GrandTouring,

On the first flight my Xtra Easy also wanted to climb at low thrittle settings. What I did was adjust the elevator clevise to give a little down elevator when the controls and trims are centered. Just unclasp the clevise from the control horn, turn it in a couple of turns then get back in the air. Final adjustments can be made with trim. I adjusted mine so it would maintain level flight at 1/3 throttle or so. It will still do basic aerobatics without much trouble. Hope this helps.

I should have asked at what throttle setting does your trainer climb at? Trainers are built to climb at full throttle, cruise along at level flight at 1/2 throttle and descend at less than 1/2 throttle. Its a safety thing, if something goes wrong, go full throttle and the plane will climb. If the plane is still climbing out at 1/2 throttle or less then I would mechanically adjust as mentioned above for level flight at the 1/2 throttle setting. If you adjust for correct trim at centre then you don't need to remember where the trim was when you flew last. If you do this for all your other planes that you get, then model memory isn't an issue. About the flaps, when you lower them they create tremendous lift which is why the plane will nose up if you aren't ready for it and adjust the trim accordingly. Its the same for full size planes as well.

Definately start by setting your ailerons to be level.

Another thing to check.

What is the incidence of the wing? Many trainers, including mine (GP PT40 Kit), needed the popcicle stick adjustment. Sounds silly, huh. Well, all you do is place a popcicle stick in the wing saddle under the trailing edge of the wing. If it stops climbing (make sure all the controls are set to neutral) you have solved your problem.

I too had trouble with my Extra Easy at first. I shimmed the trailing edge of the wing 3/8" in order to have it not climb. Now after one year it still flys level even in the wind.
I hope this will be of some assistance to you.

Regards,
Frank L

ok I haven't had a chance to try the spacer under the trailing edge but heres what I'm curious..

You all have mentioned "true neutral" Should you trim every plane this way? and should ALL controll surfaces be neutral? or just the elevator?

What if you build a plane and it tends to want to roll to the left of right? Would you just correct with aileron trim or is there a certain way your really supposed to trim??

this entrigues me because every plane I have ever flown since I was eight was all trimmed with the trim tabs unless it needed more then it was trimmed with the clevis.. This was even done by instructors for me too....

I've flown some of my planes with the elevator up, ruder slightly left and alerons slightly to the left to make them fly??

And lastly if they require shimming and things why don't they build them that way from the factory (arfs and such)??

Please don't take offense to this, after reading it I kinda think it could seem like a backlash, ITS NOT.. I'm just wanting to understand these things better!
Thanks!

Think of mechanical trimming this way. If the plane is always going to the left and you adjust for level flight by using the trim tabs then everytime you bring the plane out you will need to adjust with the trim tab. If you adjust by turning the clevices in the right direction, you can get the plane adjusted so that the plane will fly level with the trib tab at centre position. Just make small adjustments, say 1 or 2 turns before a flight so that the change will be noticable but not drastic. It may take 2 or 3 flights to get it perfect but so what? Once you have it, you don't need to adjust the trims again. I would make the adjusts for what ever needs the most trim first. If the plane wants to climb like crazy, then I would work on the elevator adjustment first. Then start adjusting for the ailerons and rudder. If you adjust everything at once the next flight could give unexpected results so try one setting at a time. The trim for the engine idle is different for most planes so don't bother trying to get that the same. If your other planes are this way as well, you just centre your trim tabs, adjust your engine, set your idle speed and take off. It makes it very easy to switch between different planes on a nice sunny day.

ok that I understand and is good info,
what I'm confused about is the shiming..... changing the incidence of the wing....

Why don't they make the kit to where you don't have to do that? is there a certain reason? I'm gonna shim my wing as soon as were done with the float fly because I don't particularly like flying with about 3/8" down elevator trim.

I'm just curious as to why they didn't incorperate it into the kit so it would fly level? And also if there is a way that your supposed to shim a wing if it flys to the right left etc...

So that the plane will be trimmed and the controll surfaces all neutral, as in "in-line" with the vertical and horizontal stabilizers??
Same for ailerons

Jeremy, I believe this wing attaches with rubber bands? How many do you use? You need about 10 - 12 to do it properly. If you do not have the wing secure with enough of them, it will "pop" up at the leading edge during flight, changing the incidence and causing the plane to climb, especially under full power. Just a thought that many overlook.

I use 12 minimum....
I can see how trimming it would help (setting the incidence) it just boggles me why they didn't make it into the kit already set..
is it because it's a "trainer" type plane?

I sympathize with your exasperation re: trainer wing incidence. These offbeat features I'm sure are incorporated with the aim of making the design more foolproof in the hands of a beginner. I forget what all the changes are that I put in my Senior Telemaster, but my recollection is that the wing incidence, the downthrust, the tail decalage were all too much for my taste, even as a fledgling RC flyer (although I had built and flown many freeflight and U/C models in my younger days).

It's experiences like this that will make you a more thoughtful, more discerning RC aviator. Be assured that the tried and true "second plane" models are much less convoluted in their designs.

Welcome to the Extra Easy climbing school. This is a know "feature" with this plane, even one of the popular reviews identifed this in it report ( can't recall which one now, but if you really want it I can find it). I used about 3-4 popsicle sticks, and proper balance with nose weight, and its better. I might try a few more to make the bottom of the wing parallel with the rear stab for better results ( ie more sticks).

I played with many levels the downthrust but it did not correct the situation. As a previous post said, I agree that it is designed to climb at full throttle. I'm still curious to hear if anyone has completely eliminated this feature so that it flys consistent at any throttle level.

Ok, with the extra easy,

How its asembled, what if I shim the front of the horizontal stab?
It would be nothing to undo the stab's and "build Up" the front of the mounting location.....

would this work as well?

The think I'm worried about is if I do shim the rear of the wing, then my wing will be very close to being "higher" than the rear turtle deck, and although the rubber bands hold it on, its still possible for the wing to slide rearward...??

Your right, this can happen. I took a small piece of sheet metal and cut it into the shape below to preven wing from slipping back, and just cliped it in place in the fuselage with 3 binderclips so its quick & removable. It's a U shaped. If this isn't clear I can try a photo later. Had this about 2 years, no problem. Also use wing tape to prevent air getting under wing and into fuselage Good luck Mike

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well tonight I'm gonna take off the gear and lay the fuse on my workbench (the bottom of the fuse is flat)
and measure from the front of the stab to the bench
and from the rear of the stab to the bench

Then I'm gonna measure from the leading edge of the wing down
and from the trailing edge down..

I'm gonna try to build up both....
Make the wing at almost 0 incidince maybe 1 degree positive and make the stab at 0 or -1 incidence...
If I think correctly if the wing was at positive incidince (leading edge sets up higher than trailing edge)
and the horizontal stabillizer had negative incidence (Front of it was lower than the rear)
It should create a plane with the dynamic forces for it to want to keep climbing, like my plane is doing....

Is my theory correct?

I think your theory and approach of incidence adjustment is correct, providing you dont overcompenste by doing both, but the practice of measuring to the bottom of the fuselage on a table may give unpredictable resulst. The bottom of the fuselage may not be parallel to the thrust line. I think an incidence meter to make the bottoms of both parallel would be more in order for this type of redesign. I'm very interested in your results, please keep us posted.

P.S. unrelated tip, I also changed the gear screws with three 1 size larger nylon screws, then ran a clear plastic 90 degree corner molding (the shower type) along the bottom of fuse. This protected the fuse in the event of a hard landing where the gear comes off and protects the fuse from gear impact damage.

Well.....
I was just going to set everything to a "neutral" type setting
The only thing is, if it has to be related to the thrust line of the aircraft, its gonna be hard.......

The reason is because if you notice on an extra easy it has a large amount of downthrust incorperated into it. The Firewall has a very forward slant to it.....

Hmm..... now this changes things.. I'm not gonna go hacking the firewall....

I'll check out the wing/stab first make some adjustments a little at a time and see.....