nheather

jaka

Hi!
Sounds as if you have way to much elevator travel! This could be due to too forward Cof G! How much elevator travel do you have (in mm at the trailing edge). I assume 10mm would be enough if the Cof G is "correct"

nheather

Skyhawk940

I would take out all or most of the expo. When I have used expo, 30% or more, I tend to way over control. A little, little more, little more, WOW, too much!! Whenever I do use expo, it's 5 to 15% If you are using recommended throws, you don't need much expo. If you are using some wild throws (3D), then you will need some more expo. Your last flight sounds just like one of mine with too much expo, thinking it would calm things down a bit. It ended up with too much over controlling and a hard time bringing the plane home.

Skyhawk

r ward

in a banked turn, the tail is affected by gravity and centrifugal force and the deflection of airstream over the elevator, but no one single for is prevalent. in comparison, the effort need to raise or lower the tail in level flight is greater because gravity is the prevalent force at work . using elevator in slightly banked turns acts on two forces that neither one is prevalent in the plane of displacement so the displacement of the tail becomes easier in the bank, resulting in what appears as a flair. adding some rudder to counter adverse yaw in a bank, compensates for the lack of gravity's pull because the plane of displacement is neither fully vertical or horizontal.

born2build

But it's just a Big Stick (Ugly Stick)! This ain't rocket science. I have no clue why Nigel is having these problems.
As I've said before, this plane should be a no-brainer.
P.S. Nigel. take out all of the expo. You should not need it.

nheather

That is what is puzzling me. I understand the science but what I can't get my head round is how aggressive the pitch up is. And especially as I have flown plenty of planes before and none have behaved like this.

But I will take out the expo for the next flights.

Cheers,

Nigel

born2build

I know, right? I also know you've got plenty of experience so. I'll leave you to it. Let us know how it goes.
Happy landings!

tedsander

There still may be a bit of a CG mismatch, but at least subsequent flights have shown it to be not wildly off. Next time you fly, try this:

Rusty pilot test, but not too accurate:
Trim for full power level flight. From straight and level, full power, bank to 45 degrees. Do NOT touch the elevator. Does it tend to descend - a little or a lot? Or does it stay level, or even climb a bit? If the first - it may be either right on, or nose heavy if it descends quickly. If level or climb - tail heavy. Better to err a bit on having a little descent, than to stay level - which may become tail heavy as you burn off fuel.

The better, but more skilled pilot test:
Trim for full power level flight. Fly straight and level, full power. Pull up to a 45 deg. climb. Neutralize elevator. Roll inverted. Do not touch elevator. If plane does a nice, long gentle arc down, CG is about right. 3D guys look for a continued straight line, but this isn't a 3D plane. If it climbs when inverted, it is tail heavy.

While a Stick isn't a full bore pattern or 3D airplane, it IS still a pretty good aerobatic plane. So I wonder as to why it is going into a nice, wide banked turn on just ailerons. It should continue on mostly straight, or with a gigantically wide turn. Make sure that is actually happening and that you aren't subconsciously feeding in a slight bit of elevator to compensate for any loss of altitude it might have (which would also produce a turn)

Early on you mentioned thrust. Do this:
Trim for full power level flight. Fly full power, straight and level. As it approaches you, chop the power to idle. Do NOT apply elevator. Watch what it does in the first few seconds after chopping power, before it slows a lot. If it starts to climb, even a bit, you need upthrust. If it starts to dive, you need downthrust. You want to see it maintain level while it still has speed, gradually transitioning to a shallow descent. You may have too much downthrust, causing you to carry some up elevator to compensate - which could also exacerbate the turn issues you are seeing. But get your CG and thrust sorted out, before chasing the turn issue.
Note: If you are tail heavy, it can sometimes look like a thrust issue - the plane has some down elevator (makes more lift) to help carry the weight on the tail at full throttle. When you cut power and loose airspeed, the tail can't provide as much lift and the tail drops. Causing the nose to pitch up - making it look like you need upthrust. So verify the CG by doing the above tests several times, before messing with your thrust lines.

The point of both the above is to eliminate, as much as we can, elevator trim that is needed for other issues, that may be contributing to your turn concerns.

And while you have seemed to indicate that the ballooning is not really present...check your pushrod to the elevator for flex! When you try to move the elevator by hand, you should not be able to move it unless the servo arm itself moves. If your pushrod is bending under load, it can lead to all sorts of poor handling situations.

jester_s1

I'm just taking a shot in the dark at this point here, but could it be that you have some significant adverse yaw and so not banking the wings as much as you'd expect, resulting in the up pitch when you expected it to turn? If you have the ailerons set up with equal throws up and down, you definitely have some adverse yaw.

nheather

Thanks.

I'm taking the expo off. If I think back I have never flown with it before except when I started to learn on helicopters. I'm a 'thumbs on top of sticks' person, an my heli tutor tried to reprogram me to use the pinch method but it was just too alien. So he put in expo to soften it around the centre. So probably still need it for helis but not fixed wing.

As for ailerons - yes they are equal. I've never felt the need to use differential ailerons before, but worth a try, I will put it in before the next flight.

Cheers,

Nigel

DGrant

My Feedback: (4)

Did you get a chance to do any of the tests I'd mentioned in post 13 and 43? Those are just a few of the attitudes and exercises that can be done that might/can offer insight.

As mentioned, it's just a Stik. We've all had a few of them at one time or another. I have one right now. It's one of the best flying sport planes I have.

Nigel, your Stik is very much a mystery. Good luck with it, I hope you get it figured out.

nheather

jaka

Hi!
As the others have said : Its just a ARF Stick and as such should fly just perfect right out of the box if the Cof G is at 25-30% cord.
Change elevator servo! And then set up the linkage so it is stiff.

jester_s1

I'd leave the expo too. There's a good reason why it's in every computerized radio on the market- because nearly every plane you'll ever fly flies better with it. Most planes get a linear feel to the controls somewhere around 30% expo. Sure, you can get that almost/too much break over with too much expo, but the amounts you were using aren't going to do that.

jaka

Hi!
Expo isn't the culprit! Might be a faulty servo though. Pictures of the set up would be nice.

born2build

I've rarely, if ever flown with expo. I don't like the increased sensitivity at as you move the sticks.I suppose it's good for 3-D type planes with huge control surfaces and massive throws, but that ain't what we're talking about here. Again, it's just a Stick!

born2build

Nigel,
Check your aileron linkages. Make sure the geometry is correct!

nheather

Thanks for the suggestions.

EXPO - I will remove this - it is a hangover from my helicopter flying - I have never used it for fixed wing before. I'm a dyed in the wool, 'thumbs on top of sticks' flyer which is not the best for heli flying. I did try converting to the pinch method but it was far to alien to me. The problem with heli flying is that you need constant tiny precise movements around centre which is difficult to achieve with thumbs on top. So the remedy is add expo which reduces the sensitivity for at the low end.

AILERONS - at present, it is set up as per instructions, equal movement up and down. Someone has suggested turning on differential ailerons and I will try that.

But to be honest, whilst I'm happy to try anything, I'm not holding my breath. After all this is just a STICK and it should just fly - that has been my experience with sports planes up to now. Fiddling with expo, differential ailerons, tiny changes in CG might finesse the performance but they are going to be the difference between flying badly and flying nicely.

Cheers,

Nigel

born2build

Okay, Nigel. I ran across a few videos on You Tube of Big Sticks flying. They flew perfectly. I'm stumped.

nheather

born2build

Okay, I watched the video, such as it is. I had to move it to my You Tube channel to see it full-screen.
It seems the pilot in the video lacks certain skills. But that's a different topic.
A barrel roll requires some up elevator along with aileron input, as well as rudder, depending on the design. I'm afraid without flying the plane myself, I can offer no further advice in regards to your problem, except to again suggest you let another pilot fly your plane to get a fresh perspective. I know you don't want to do that. But, maybe just take it up yourself and hand him the transmitter?
Other than that, I don't know what else to tell you. Good luck.

Regards,
Richard

tedsander

Hope you get out for some more flight testing soon - is this the plane you are also having problems with the Magnum engine?
As a couple of us have noted:
1. Make sure all flight controls are solid - unable to flex under load, servos are holding against loads, no slop in linkages. That is the most common cause of the issues you are seeing.
2. Finalize your CG and engine thrust by flight testing as noted previously. This removes them from consideration.

A Stick, or similar airplane, should not do a wide turn on ailerons alone. Period. With a symmetrical airfoil, low/no dihedral, and wing close to the centerline, it should only roll. Maybe not perfectly axial, but it should not do a turn. Verify this turn is really happening, and you are not unconsciously inducing the turn by slightly pulling back on the elevator. Bank to 45 deg or more, and let go of the stick completely, and just watch.
If it really is, then likely you are carrying too much "up" elevator when level. As you bank, the wing is no longer fighting gravity, and the excess lift goes into making the plane turn. (And then you add in even more by pulling back on the stick, and it balloons....) Improper engine thrust would be the first cause of needing to carry up elevator. And CG can impact engine thrust. Hence why getting those two set right first are critical.
Only after that should you then delve deeper into wing/tail incidence, etc.
Expo is personal preference. But if you are comfortable enough not to use it, do so - one less thing to factor into the complexities of trying to sort everything out.

r ward

as to pushrod flex,...I use carbon arrow shafts with typical pushrod wire ends epoxied into them. they weigh nothing and are about as rigid a pushrod material you can find. I use a marine epoxy designed for fixing gelcoat on boats. it is relatively thick and very adheasive to both the arrow shaft and the steel pushrod material. I usually glue about 2 inches of pushrod into the shaft by filling the end of the arrow shaft and leave enough steel shaft to exit the fuselage with only the wire. I also put a small bend in the steel shaft inside the arrow shaft to ensure it won't slide out, should the epoxy fail, but never had a problem. I've tried all sorts of methods/materials and I don't think you can make a lighter, stiffer linkage than this for the money.

Lee Taylor

This is not a question but just food for thought. Very low stick time can cause extremely wild, erratic, jerky, panic stricken short flights. Just sayin... no response necessary