Spring loaded controls

[metalman]

Hi all, has anyone flown their skyfox/gazelle without the rudder springs on the pedals or the aileron centering springs, the reason I ask is I have a problem flying straight and level and keeping the ball centered, it won't fly "feet off" and after a couple of hours it gets very tiring to have to keep weight on the pedals, unless there's a rigging problem I might be able to tune out of it,

 

cheers Matty

 

 

[planesmaker]

Hi all, has anyone flown their skyfox/gazelle without the rudder springs on the pedals or the aileron centering springs, the reason I ask is I have a problem flying straight and level and keeping the ball centered, it won't fly "feet off" and after a couple of hours it gets very tiring to have to keep weight on the pedals, unless there's a rigging problem I might be able to tune out of it, cheers Matty

Hi MM yes my skyfox doesn't have the aileron centring springs. I did not know it was meant to have them till somebody else mentioned it to me a couple of weeks ago. They have never been on there since I bought it 2nd hand not long ago. Tom

 

 

[metalman]

Hi MM yes my skyfox doesn't have the aileron centring springs. I did not know it was meant to have them till somebody else mentioned it to me a couple of weeks ago. They have never been on there since I bought it 2nd hand not long ago. Tom

Is it light on the stick inflight?

 

 

[planesmaker]

Y

 

Is it light on the stick inflight?

Yes it is and I like it. Though don't know how it feels any other way. Tom

 

 

[Methusala]

No spring on the aileron circuit of our Kitfox! I would be surprised if there was. The rudder springs only keep the pedals upright. I don't think the springs exert any force on the rudder. Don

 

 

[old man emu]

I have a problem flying straight and level and keeping the ball centered, it won't fly "feet off", unless there's a rigging problem cheers Matty

First Rule of fixing things: Always look for the simplest solution before getting into complicated solutions.

 

If I was you, I'd go back to Aerodynamics 101: If a plane is to fly straight and level, all the forces acting on it must balance out. Find out what's out of balance.

 

Q1. Which side does the plane keep wanting to turn to?

 

Q2. What would make a plane turn in that direction?

 

Q3. Are the wings rigged level? (Check several points equidistant from the wing root.)

 

Q4. Does one of the ailerons droop?

 

Q5. Is the rudder rigged correctly (allowing for some offset for prop wash effect)?

 

Q6. Are both sides of the fuselage equidistant from the fore/aft centre line.

 

You can see that the answers to Q3 to Q6 can be found simply by using a tape measure, however it is probably best to buy a few metres of clear plastic tubing from a hardware store, fill it with water and use it as a water level to make sure things are level.

 

Hope you find that the answer is simple.

 

OME

 

 

[metalman]

Thanks OME, I was thinking a remeasure might be in order , short hops around the valley don't always show up problems , I've just done about 43 hours in the last ten days and all the niggely things get pretty annoying after a few hours in the seat

 

 

[Blueadventures]

Hi MM Have you made the jig to check the ailerons are on correct degrees in the neutral stick position. Give me a call if you like. If your setup re check is correct you may need to adjust the spring hanger a little until its right. John Mc told me some time ago that he would adjust the hanger position a little between flights until correct, then mark the position as a refference for future. I did this on mine and its alway hands off/ light touch of course.

 

Cheers Mike 0477634179 Nice flight times, good to hear fuel being consumed.

 

 

[old man emu]

If your airplane is not rigged correctly, you'll also find that it cannot meet the performance figures claimed for it.

 

How does yours compare to other people's?

 

OME

 

 

[metalman]

If your airplane is not rigged correctly, you'll also find that it cannot meet the performance figures claimed for it.How does yours compare to other people's?

 

OME

Much better, but I also have more HP, I'll have to get in at look at the rigging

 

 

[Blueadventures]

Hi MM Have you made the jig to check the ailerons are on correct degrees in the neutral stick position. Give me a call if you like. If your setup re check is correct you may need to adjust the spring hanger a little until its right. John Mc told me some time ago that he would adjust the hanger position a little between flights until correct, then mark the position as a refference for future. I did this on mine and its alway hands off/ light touch of course.Cheers Mike 0477634179 Nice flight times, good to hear fuel being consumed.

Hi MM Did you get the roll sorted?

 

Mike

 

 

[metalman]

Not yet, it gets worse as I use fuel as it doesn't pull equally from each side, I'm also going to set it up and check the rigging right through to see that it all good. Another thing I've found is when I start a turn I use a small amount of rudder to over come the adverse yaw but then I have to use top rudder to keep the turn co ordinated, I'm getting used to the plane but occasionally it feels odd and a look at the ball confirms why. I'm hoping to get the chance to go over it in the next few weeks , and I'll also try it with out the springs on the controls

 

Matty

 

 

[facthunter]

The amount of power on will vary things. You can almost cancel it out with engine offset . which I like because if you do it with rudder offset or trim it will be a problem in glide. I think I would start with wings level against the horizon both sides and see what happens with the ball. ( which should be centre when still on a level surface). All as a start point only, but you must check what happens when the power is on and off. Nev

 

 

[metalman]

The amount of power on will vary things. You can almost cancel it out with engine offset . which I like because if you do it with rudder offset or trim it will be a problem in glide. I think I would start with wings level against the horizon both sides and see what happens with the ball. ( which should be centre when still on a level surface). All as a start point only, but you must check what happens when the power is on and off. Nev

Thanks for the input Nev, I've flown it feet off and it tends to hunt a bit, rather than being out of balance one way or the other it tends to yaw one way then slowly yaw the other way, we're talking half a ball here. It has more hp than the original and cruises around 8 knots faster, I was thinking a bit more offset to the engine thrust line might help. I need to eliminate some of the other surfaces by checking the rigging though, just to be sure nothing is causing an issue,

Matty

 

 

[Tex]

Adverse yaw?

 

 

[old man emu]

Thanks for the input Nev, I've flown it feet off and it tends to hunt a bit, rather than being out of balance one way or the other it tends to yaw one way then slowly yaw the other way, we're talking half a ball here. Matty

That makes me want to retract my suggestion that an aileron could be drooping, or that the wings are not rigged correctly. If the airplane oscillates back and forth, then Newton says that there has to be a Force applied to start the movement, and importantly, another force to stop and then reverse it. My hunch is that there is movement in the vertical stabiliser. Check for security of your fin.

 

OME

 

 

[Blueadventures]

Thanks for the input Nev, I've flown it feet off and it tends to hunt a bit, rather than being out of balance one way or the other it tends to yaw one way then slowly yaw the other way, we're talking half a ball here. It has more hp than the original and cruises around 8 knots faster, I was thinking a bit more offset to the engine thrust line might help. I need to eliminate some of the other surfaces by checking the rigging though, just to be sure nothing is causing an issue,Matty

Hi MM Have you adjusted the aleirons with a little negative deflection when in the netural position? Pehaps you may have them set at 0 degrees netural and during level flight the play in the control circuit is floating them up or down that little bit that your noticing. I'm not an expert so this comment is not meant to be expert or setup adjustment advise so check for assistance with an authorised maintenance person. Cheers Mike

 

 

[metalman]

Nah the vert fin seems fine, I mean I give everything a good wiggle as part of a preflight and it doesn't move unusually ,I've heard that not having a big enough rudder will cause it to not trail properly, maybe ,I'll have to look into it

 

 

[old man emu]

I am still concerned about the oscillation.

 

 

[metalman]

I am still concerned about the oscillation.

Me too, it's not fast though, just wanders

 

 

[metalman]

Hi MM Have you adjusted the aleirons with a little negative deflection when in the netural position? Pehaps you may have them set at 0 degrees netural and during level flight the play in the control circuit is floating them up or down that little bit that your noticing. I'm not an expert so this comment is not meant to be expert or setup adjustment advise so check for assistance with an authorised maintenance person. Cheers Mike

That makes sense actually, I'll look at it,

 

 

[frank marriott]

Me too, it's not fast though, just wanders

Reminds me of some of the old Cessna 2 axis auto pilots - nearly enough to make you sea sick.

 

 

[facthunter]

It might just be exhibiting fairly neutral stability. Nev

 

 

[metalman]

As I think about it in flight there's a feeling of lightness in the stick ,the only other thing I can relate it to is a car with not enough castor ,I'll look at the ailerons they might be in a neutral position which is causing it to roll slightly ,Inturn causing the feeling of a Dutch roll ( I know it's a higher speed thing) ,the imbalance of the fuel usage alps causes balance issues as the weight drops, I might have to look at setting up a tap to control the tanks more accurately

 

 

[Head in the clouds]

..... I've flown it feet off and it tends to hunt a bit, rather than being out of balance one way or the other it tends to yaw one way then slowly yaw the other way, we're talking half a ball here....

I had a problem like this a long time ago and didn't find the answer until years later. I'm not guaranteeing it's the same thing but could be worth checking.

 

I built a fully enclosed pod for the Drifter, ugly looking thing but it was nice and warm in winter, but it had that same wandering problem, feet off it would slowly oscillate a long way side to side, I never measured it but it seemed like 15-20 degrees each way. I just assumed that the amount of side area forward of the CG was too great and was overbalanced compared with the vertical stabiliser, especially since the Drifter doesn't have dorsal or ventral fins.

 

 

Not long after that I sold the Drifter and went flying commercially so I didn't worry about it any further.

 

About ten years later a fella in Arnhemland had an American ultralight that was a copy of a Challenger and it had the same problem. He fitted VGs halfway down each side of the fuselage and it fixed it completely. His apparently correct theory was that the flow was semi-laminar on the fuselage sides but any deviation from straight ahead would turn the flow turbulent further forward on one side than the other. That meant more lift on the attached side so the fuselage would rotate toward the lifty side. Eventually it would reach an angle where the fin took over and it would cycle back the other way.

 

It most likely wouldn't apply to yours because the fuselage is in the prop wash but if you don't find another explanation it would be easy enough to put a strip of something down the front of your door line to break any attached flow and see what happens.