wing "unbalanced"/pulls to one side

[soekiwindni]

I need some info on the following problem I have with my Cosmos wing :
At normal cruising speed (45-50 mph) handsoff : wing keeps straight and is totaly "balanced", BUT it is off-centre and barr is about 10 cm more to the left (as if I want to turn right).
Close to stall (33 mph) the trike dips to the right (the right wing drops).

Question : Why does it fly straight even though the barr is off centre ?
Why does the right wing drop at very low speed ?
What area of the wing comes into play at high speed...........and at low speed ?
Would it help to do something to the buttons, bungy ropes to rectify this as it must surely be balanced at any speed and the barr must be in the centre.......?

I need as much info as I can get.

Thanks.
Jodie

[Dre'man55]

I would say it is the cart of balance and not necessarily the wing as it is flying straight hands off. When you are going into the stall you are probably holding the bar tight and centre. transferring to added weight on one side into the wing causing the dip.

But maybe my logic is wrong?

[Carel]

Had a similar experience quite a while a go and it was tracked back to a large dent, close to the centre line, on the leading edge of the trailing (side side that is now "behind") of the wing. Once the leading edge was fixed the problem dissapeared. Till today no clue about how the dent appeared on the leading edge.

A bent pylon can also cause the symptoms as described above as that was the first thing checked by the experts.

[Wargames]

Bent leading can do the same in the stall!! First check that battens left and right give the same aerofoil shape. Only then start looking further. I had worse problem, and it was a bent leading edge.

In strait and level, check the lenght of your flying wires. if they are the same, Id say that you must tighten your wing to reduce the dihedral of the wing.

My advice:

1. Check battens left/right same shape.
2. Make sure bungee chords left and right same tension on battens.
3. Tighten wing to reduce dihedral to check straight and level balance.
4. If problem persist, check leading edges is the same lenght and shape.

Let us know if you find the problem.

[kloot piloot]

Jodie, you say the wing is balanced but 10cm off-centre when at cruise.

Question: In the above configuration, if you let go of the bar, does it keep flying straight ?, or do you have to hold the bar to fly straight ?

[KFA]

Question: In the above configuration, if you let go of the bar, does it keep flying straight ?, or do you have to hold the bar to fly straight ?

mmmm, answer

At normal cruising speed (45-50 mph) handsoff

[kloot piloot]

KFA, you are thinking like I am. Are the hands really free and away from the control bar ? Wing flying itself ? If so, Dre'man55 is correct. The centre of weight (COW) on the cart is way out. But 10cm on the control bar means a hell of a lot of additional weight somewhere on the left of the cart.

If this is the case, then Dre'man55 is right that Jodie might be trying to neutralize the bar and the right wing will stall.

The big thing about a delta wing is NOT to start bending battens as soon as a wing is stalling to one side. There are lots of simple remedies before you start bending battens, thus stuffing aerodynamics up even further.

With regards to Jodie's other questions: The root of the wing creates the lift. I.e. from the nose batten to battens number 5 or 6 (depends on wing). The rest of the wing, from the flying wire connecting on the leading edge, and outwards, play very little effect in straight and level flight. Battens numbered 6 and onwards only determines trim and stall recovery behaviour. The wing tip battens only start working with a high angle of attack or when stalled, otherwise they "float" along.

Let us know Jodie.

[Wargames]

If this is the case, then Dre'man55 is right that Jodie might be trying to neutralize the bar and the right wing will stall.

Kloot, This is a funny one to picture. If Jodie has the bar center, he will turn. And in a turning stall (Incipient spin) you will always have a wingdrop. The question is whether he is stalling straight, and then have a wing drop?? (ie: bar not centered, but flying straight!) Then there is something wrong.

My 2c!!

[soekiwindni]

"The question is whether he is stalling straight, and then have a wing drop?? (ie: bar not centered, but flying straight!) Then there is something wrong."

Yes, the bar is not centre when stalling, but flying straight.
The cart may be slightly off-balanced. The last "Mass and Balance" indicates front wheel 44kg, rear left 56kg, rear right 58kg. This can not cause the problem ?
Will go to airfield this afternoon and look for any "dents" or "bents". Will also tighten the bungies.

Will keep you posted.

Thanks for all the help/replies.
Jodie

[Mogas]

I used to fly a Cosmos wing.
The sail was very "slack" but it flew fine.
One day I thought I would tighten up all the bungees just to make it look nicer, get all the wrinkles out etc.
The first flight after that I got a really big skrik! Wing pulled hard to one side and roll control was extremely heavy.
In hind sight I think I took out most of the billows shift, anyway straight away I slackened off all the trailing edge bungees again and it was fine.
Just be careful when you tighten it up. Hope you come right.

[Stephan van Tonder]

No you only have about 2 kg to the one side - won't cause what you describe. I'd speak to a wing builder like Jenya and maybe have him take a look at it.

[Splinter]

A very experienced pilot once told me " dont F@#k around with it". You might get it to fly / stall straight and level now but one day you sell the plane and the new owner gets a similar problem. Trying to fix the problem he adjusts the wing tips or battens causing a wingtip stall or worse because he does not know how you "manipulated" the wing before. Who knows you might just be the second owner!!!! My honest opinion get in your trike, fly it as is, to Yenya in Petit and let him fix it!!! He is one of the best if not THE best in SA.

ZU-RED

[Blue Max]

Tie the wing to the profile tube exactly on the centre of the control bar, if the wing hangs to one side,the only reasonable explanation is that the main pilon is not 100 % plum. I think about it this way: The control bar is attached to the wing in a fixed parallel position... In order for the controle bar to rest exactly in the centre of the plum profile tube the main pilon need to be precisely 100% plum. Stand some distance behind and in front of your aerie and see if you can notice a slight deveation of the main pilon.
I have noticed that on some trikes the fork and nose wheel is not 100% plum because the position of the hole by which the fork is attatced is not drilled 100% correctly and in equilibrium with the rest of the frame. This I think might be the same ( If not something else) as far as the attatching of the main pilon is concerned.
I have the same problem with my aerie, the wing is not staight and level when the control bar is tied in the centre to the profile tube. I have noticed that the main Pilon is not plum in comparrison with the frame.
I have only 10 hrs since obtaining my licence and contrary to my taking of with my instructors aerie on a straight course above the runway my own aerie takes of and loses the runway underneath it as soon as it gets airbourne!!!! I am of the opinion the "skewe vlerk" is the reason...To me it sounds as if you might experience similar problems...Somebody out there, give us your opinion!!!

[soekiwindni]

I took the wing down, took all the bungees and battons out, folded the wing (closed it). I then set it up again, tighten the bungees and guess what................the wing is still off-centre and close to stall the right wing dips! It flies straight without pulling to left/right, in fact, it flies like a dream!!!
Thinking of leaving it as is.....or am I taking a change?
Soekiwindni