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Oodalally

My latest quickie design

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D for Donald10/08/2016 07:13:20
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I'm thinking about retiring my Ood after it's 4th crash. I find it very tip stall prone and impossible to fly slowly for landing without it dropping out of the sky. Any suggestions?

Denis Watkins10/08/2016 07:45:41
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No disrespect Don, but C of G is crucial, as always, and are their any gaps in the control surfaces, especially the elevator?, these want taping up

Edited By Denis Watkins on 10/08/2016 07:46:21

Peter Miller10/08/2016 08:08:05
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I find that strange. Mine was most forgiving and others have not complained about the slow speed handling. Mine never showed any tp stalling tendancy.

Just where is your CG.?

Edited By Peter Miller on 10/08/2016 08:08:58

D for Donald10/08/2016 08:50:22
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Hi all, no disrespect taken but to explain I've been modelling for over 50 years (oh dear!) and the surfaces and C of G are on the button per the plan. I have noticed particularly that if the engine cuts in flight the tip stalling is particularly violent if the nose is not kept well and truly down. We have a limited strip as to length and width so we have to come in accurately and not at excessive speed if we are not to overshoot. If we had a large mown field the speed wouldn't matter too much. The glide is not good.

Denis Watkins10/08/2016 09:09:44
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Ditto on the 50 years Don, you would think that we had learned by now ! I am a small model man and they can play up on us. Lateral balance too is a consideration, but your strip, being an aircraft carrier, perhaps puts the pressure on too. These model types, I do fly in on to the wheels, then cut the motor, I dont even try a glide, but I do practice at height to detect a low speed wing over.

C of G may be on the plan button, but it does sound like your build is "leaning back" a little. Weight is our enemy, and adds speed as you know, but I dont recommend we mess with wing incidence packing at this stage as you sound an accurate builder.

Add weight, just to try, way forward, up nose as far as you can get it, while watching the balance point is nearby

Edited By Denis Watkins on 10/08/2016 09:11:27

kc10/08/2016 10:13:55
5860 forum posts
168 photos

Is the overall weight much more than the 4lb 3.5 oz that Peter's model weighed according to the article?

 

Check for any twists in wing or tailplane & elevator. Check for excessive aileron or elevator movement. Check rate switches are set correctly. Check wing to tailplane alignment, particularly check wing bolts and dowels are holding wing firmly. Double check CG is as per plan and measured at the correct place ( it's a double tapered wing on this design isn't it so possibilty is it was measured at wrong place )

Check Tx for any unexpected coupling or exponential that you didn't set - especially if you let someone else play with the Tx ( particulary check expo is the right way for your make Tx - Futaba is opposite to Spektrum )

If you eliminate all the possible problems with the plane then consider whether it is possible that your thumb is actually giving a steady movement as you expected or perhaps jerking a little ( especially on Mode 2 ) Can happen!

Edited By kc on 10/08/2016 10:14:43

Peter Miller10/08/2016 12:37:32
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I am completely baffled.

Does it tip stall in one direction or either direction. I am assuming that you built the wings according to my sequence in the building instruction in which case it is impossible for a warp to creep in.

The weight would be interesting to know. The CG is measured from the leading adge up against the fuselage side so that should impossible to get wrong. It is at 25% chord whch is extremely safe for any model.

Incidences are all at 0-0.

What engine are you using?

D for Donald10/08/2016 16:17:01
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Many thanks all for your comments and suggestions. It tip stalled from newly built - rocking violently left and right if the airspeed was insufficient. I am also baffled and had concluded it was just a fast model that wont fly slowly.

My Tx settings, wingbolts and thumb are OK I think. The engine is an ASP32 2 stroke.

After 3 crash repairs and now the fourth yet to be done the model will be heavier than when newly built and also the wing has been repaired twice. I will post an update when I have repaired it again and rechecked against all the suggestions.

D for Donald10/08/2016 16:28:31
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PS the rocking is in all probability me trying to save the aircraft with overcontrol of a violent wingstall to the left in the first instance.

Peter Miller10/08/2016 18:14:23
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I can't help wondering just how slowly you are trying to fly it. It isn't going to float in like a Junior 60.

On the other hand it doesn't come that fast. A little faster than perhaps Ballerina but not as fast as Marauder and I don't even class that as "fast".

Peter Miller10/08/2016 18:16:39
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Posted by D for Donald on 10/08/2016 16:28:31:

PS the rocking is in all probability me trying to save the aircraft with overcontrol of a violent wingstall to the left in the first instance.

You do realise that if the model is on the edge of a stall and you apply aileron to correct a wing drop that will instantly generate a full tip stall because the down going aileron has in effect increased the angle of attack.

D for Donald10/08/2016 18:59:26
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Very interesting comments. I'm not the best pilot in the club and not the worst but I have enough experience to know what cannot be expected in terms of slowness of approach. My hanger is 6 or 7 models and all I can say is this is the one I'm ha ving problems with. When one is 6 feet of the ground there are not a lot of options but I would appreciate comment. I was taught that you never ever apply down elevator at this stage of landing.

Peter Miller10/08/2016 19:05:44
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That depends on how nose high you are.

As I said, the strange thing is that no one else has complained about Oodalally.

D for Donald10/08/2016 19:10:45
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I'm not complaining Peter or criticising the design - just describing my experiences and seeking comments.I think it's legitimate to find out if it's just me. As an aside maybe not many people like to admit they keep crashing a model!

john stones 110/08/2016 20:33:19
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Every flyer has a different feel for a model and some you like some you don't take to, might you have too much movement set up and it's biting when slowed down because of it ?

John

Paul C.10/08/2016 20:57:04
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139 photos

Hi Don, just wondering if you have equal aileron movement up and down or have you set up differential. I had one model where I did not get the aileron control horn quite level and ended up with more down than up, that was quite exciting until I spotted the problem.

Hope you sort it soon,

, Paul.

Percy Verance10/08/2016 21:07:18
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I don't wish to be at all critical here, but having already had a number of repairs, the model will probably be heavier than when it had it's maiden flight.

The crash, repair, crash cycle isn't a good place to be really. Did the model handle better when it was new Donald?

Peter Miller10/08/2016 21:31:57
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Posted by D for Donald on 10/08/2016 19:10:45:

I'm not complaining Peter or criticising the design - just describing my experiences and seeking comments.I think it's legitimate to find out if it's just me. As an aside maybe not many people like to admit they keep crashing a model!

Hi Donald.

Iam always ready to becritised. I am far more concerned that you are having problems with it. This is what crash investigation is all about and there could be something, a slight change that looks insignificant that has changed things.

I know that there weree quite a few builder. I wish some of them would make comments on their own models.

It might throw some more light on the problem and that woud help everyone.

D for Donald10/08/2016 22:11:36
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Thanks everyone, all your comments are very instructive and I take them all on board. It's true the model gets slightly heavier and out of true with each repair but the first prang was also in the circs I've described. As a matter of interest what do others do if a wing drops so close to landing? Or maybe do you just land fast?

Peter Miller11/08/2016 08:39:14
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If a wing drops so close to landing I crash!!!

A thought occurred to me last night.Just occasionally even in full size aircraft they get a rogue aircraft that has strange behaviour for no apparent reason.

I once flew on air test in a Lancaster. part of that air test involved a stall test. The nose was pulled up and the aircraft slowed. until the nose suddenly dropped. On two other air tests this happened and was quite exiting.

On this particular test it refused to drop the nose cleanly and it just mushed along sinking slowly. They tried several times. I assume that this was the first it had behaved this way or it would have been listed in the form 700.

Never did find out why it did it. But then the Lancs were pretty old and tired by then.

You could just have a rogue model and a new one will probably work perfectly.

I know that two supposedly identical models can perform very differently. A friend and I built two Dumas Mustang control line stunters. Mine flew like a dream my friends was a dog. WE checked everything and could find no differences at all

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