Author Topic: Problems to think about  (Read 13184 times)

Happy Days

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« Reply #15 on: December 24, 2012, 06:46:54 AM »
Okay Bill, I’ll try that. Thanks for the suggestion. :clap:

 I’ll let you know how I get on. :wink:

K.
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Fred

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« Reply #16 on: December 24, 2012, 22:01:50 PM »
Very good Keith  :clap:

For  your hinges problem, do what Bill said, tape on the back, and your problem should be sorted  :D

Option B, would be to use "flap" hinges, like the one I use on the Ka3 (same type of airbrakes).
Come in various size and shape, but all the same funtion, to move the hinge axle back (sorry, can't find the English word for that  :!:

Liek the photo, but the other way if you see what I mean.
The one on the photo are the one I use.. If you need some...  :D

Education is important, but flying RC planes and gliders is importanter!

Happy Days

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« Reply #17 on: December 24, 2012, 22:25:57 PM »
That’s interesting Fred. I’ve never even heard of Flap Hinges. I’ll try the double taping first. Thanks :clap:

I love the learning aspect of this hobby. Also found Selleri’s ideas about using plastic bags when glassing interesting as well. (I could have done with that knowledge when repairing that Kubltin of mine!)

Keith
Try not to run out of airspeed, altitude and ideas....... all at the same time.

Happy Days

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« Reply #18 on: December 26, 2012, 09:50:00 AM »
I few this ‘Riser’ for the first time yesterday. :D  I didn’t bother with double taping the spoilers as this was only to be a flight off the slope.

    I kept debating whether to launch her yesterday or not, the winds were a little gusty for something as light, and of the design as this little girl.
I could hear two distinct little voices in my head;

Voice #1 “Go on,…you’ve been dying to try her out! :twisted:  It could be months before you find ‘perfect’ conditions ”………
Voice #2 “It too gusty. :?  Even if you manage a successful launch, landing her in these winds is going to be problematic.”
   
 Obviously voice #1 won the argument and up she went. And up. And up! She is certainly very good at gaining height. Eventually, after putting in a lot of down trim, she stopped gaining altitude. However she was flying very ‘nose down’. May be it was just a function of the strong lift.
   
 She has a propensity to drop her left wing. Lots of right rudder needed to keep her level. Not sure what the reason for that is. Static weight wise the wings are balanced.
   
 From a flight point of view I’m wondering if it would be better to add weight to the right wing half, or simply leave in right rudder trim to maintain straight flight? :?:

    She bounced around on the wind for 10 or 12 minutes, always wanting to go higher, till it was time to land her.

     This proved, “interesting” having never landed a two channel polyhedral before.

    The down wind section was fast and as she came over the ridge she gained height  before I could push the elevator stick forward to cancel the climb. The turn onto cross wind caused the ‘inside’ wing to drop considerably. Now loosing height the consequent gain in air speed gave much better rudder control enabling her to ‘crab’ against the cross wind and not blow back towards the trees that line the far edge of the landing zone on the west slope.

    So to the turn into wind and her final approach. (This is where it got a bit hairy! :shock: ) Picture this in your mind.

    By now she’s lost a fair bit of height, she’s probably 1-2 meters above the landing zone. As I turn her into wind, again the inside wing drops. "SHIT!" The only way I can level the wings is by centering the rudder, but then she wont turn fully into wind. Somehow with a combination of small rudder movements to and fro, I get her facing into wind, but now she’s way off from my intended landing area (on the heather, for those who know the slope I’m referring to,) and although I can’t see exactly, I think she’s flying above the road some 40 or 50 mtrs behind me, just in front of the row of trees

    Now, having got her to face into wind, she looses all forward momentum and just hovers over the same spot. I know the ground beneath her is quite uneven. She’s less than 1 mtr above the ground. I eased the elevator stick gently forward hoping she might start moving forward a little towards smoother ground. No such luck, she just gets lower, then drops onto the ground. I see one wing half fly up into the air and blow backwards. “Oh great!!” I say to myself out loud. “First time out, and I break her!”

    In fact the damage wasn’t so bad. All that had happened is the little 5mm dia carbon wing joiner had snapped and one wing half had slipped out from underneath it’s retaining wing bands. No damage sustained, apart from a dent to my ego! :oops:

Like I said, an interesting flight. Next time I’ll wait till there’s just a gentle breeze. :)

Keith.
Try not to run out of airspeed, altitude and ideas....... all at the same time.

billscottni

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« Reply #19 on: December 26, 2012, 13:06:43 PM »
Sounds like it's tip stalling to me Keith due to lack of airspeed. Keep it moving a bit more and see if that cures the problem. They're designed to fly slowly, but not to hang in the sky. They do need some forward momentum or they will drop a wing

Happy Days

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« Reply #20 on: December 26, 2012, 14:05:21 PM »
Good thought Bill but I don’t think this was tip stalling, she was flying too fast for that.

I’m wondering if I might have been too hard on the rudder, expecting sharper turns than she might be capable of. We’ll see next time out.

K.
Try not to run out of airspeed, altitude and ideas....... all at the same time.

billscottni

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« Reply #21 on: December 26, 2012, 15:30:29 PM »
OK. Check that you don't have more wash out one side than the other

andrew wallace

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« Reply #22 on: December 26, 2012, 15:55:52 PM »
bill i was thinking a long the lines that maybe one of the wing panels was warped but you might be right if there's wash out on the wings maybe keith has taken some of the wash out with covering the model
i flew Trevor's at mallusk and it was a big floater  :D
i\'m an ordinary man nothing special nothing grand

Happy Days

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« Reply #23 on: December 26, 2012, 16:41:51 PM »
Now that’s something I hadn’t thought of, :) …wash out. I’ve just been down to the model room and had a close look at the whole bird.

I can’t see any difference between the structure of the two wing halves although the covering on the left half is a bit slack out near the tip.
What I‘ve also noticed is that the rudder cables have stretched and there’s considerable play on them. So that although the Tx is set with a lot of right ‘trim’ the rudder itself is pointing straight, and very ''floppy". I hadn’t noticed that yesterday. (I didn’t look, if truth be told.)

I’ll tighten up the coverings and the cables and see how she goes next time out. I think the real answer is to wait until gentler conditions. Yesterday was a bit too turbulent.

Thanks for your thoughts lads. 8)

K.
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Fred

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« Reply #24 on: December 26, 2012, 20:18:58 PM »
Hi Keith,


I never really do it, but you can also check the wing balance.
One side heavier than the other can be of major influence on this type of glider.

Fred
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Happy Days

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« Reply #25 on: December 26, 2012, 20:47:07 PM »
Yeah, thanks Fred but I did that before I flew her. The lateral balance of the plane is to within about a gram at the wing tips

K.
Try not to run out of airspeed, altitude and ideas....... all at the same time.