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Nov 09, 2012, 10:40 PM
repeat foam bender
ruddym's Avatar
Nice. After you got 'er trimmed at 2:30, she flew like a Nutball should.
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Nov 10, 2012, 07:39 AM
Lets break some props :D
joseico90's Avatar
progress on Underball #2, some painting before gear install
Nov 10, 2012, 09:51 AM
Aerodrenaline junkie
hoverc's Avatar
thanks, already cut my 6mm one out. It does'nt have a rudder size on the plan. What size do you think is best?
Nov 10, 2012, 11:01 AM
Registered User

Motor Position


Have built 4 Nutballs all with motors below leading edge of the wing. I put a little down and a little right on them and all flew well using TLAR.

I notice some people put their motors centered on the leading
edge of the wing and some slightly above. Does this make any difference to the flying chracteristics of the Nutball?

Played with dihedral angle 15-25 and settled on about 15-17 as best for me with as large a throw as I could get.
Nov 10, 2012, 02:27 PM
Registered User
Terry Rigden's Avatar
I,ve noticed on my 10" NB that I seem to need the CG at 20% to get acceptable flying characteristics. This seem a lot further forward than the larger models I wonder if there is a scale effect coming into play here.

Terry
Nov 10, 2012, 03:38 PM
What goes up . . . Damn trees!

The importance of dihedral.


I've been having fun with my little 14" Nutball, but have never been able to get those fast rolls that are a feature of its performance. Initially I thought it was too small a rudder, so I enlarged it. Then I suspected the little AR6400 servos weren't giving full deflection under load. They were getting a little ropey anyway so I replaced them with 3.7g ones (and an Orange Rx) - No improvement.

Then I went back to first principles (and the early posts here) where Goldguy explains it how it does the trick. As the rudder yaws the 'ball, the underside of the sloping outer face of the dihedral is presented to the direction of travel, raising the outside wing, dropping the inside wing and causing the roll. So more dihedral angle = more dihedral surface = greater rate of roll . . . Simple!
I measured my dihedral which should be 1.75" in a 17 incher (so a touch under 1.5" on a 14") and found mine was just under an inch.
Sooo . . . I would have been too tricky to break the existing dihedral join, so I sliced the wings a bit further out and re-glued with more angle to make a compound dihedral. Result - It now rolls like a Nutball should

Name: Nutball.jpg
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Description: Compound dihedral
Last edited by AndyGadget; Nov 10, 2012 at 04:15 PM.
Nov 10, 2012, 03:48 PM
Foam, foam on the range....
didge's Avatar
Quote:
Originally Posted by hoverc View Post
thanks, already cut my 6mm one out. It does'nt have a rudder size on the plan. What size do you think is best?
Dimensions are all listed in Post #1, and are also on the plans in Post #16.

Cheers
Nov 10, 2012, 04:15 PM
flyin' fool
goldguy's Avatar
"I notice some people put their motors centered on the leading
edge of the wing and some slightly above. Does this make any difference to the flying chracteristics of the Nutball?"

Seems not, as long as it's not too extreme like the SnowBall.
Nov 10, 2012, 04:21 PM
flyin' fool
goldguy's Avatar
Quote:
Originally Posted by Terry Rigden View Post
I,ve noticed on my 10" NB that I seem to need the CG at 20% to get acceptable flying characteristics. This seem a lot further forward than the larger models I wonder if there is a scale effect coming into play here.
Terry
I don't think 'scale effect' plays a roll here, just differences in building, setup, materials and personal CofG tastes. I'm flying my indoor at almost 40%, but I'm flying it all the time, no gliding going on. Right now I've got three in different sizes, all maidened at 25% and none are anyway near each other in CG location, but all rearward, not forward. That's because I'm interested extreme flying and not interested at all in how it glides.
Last edited by goldguy; Nov 10, 2012 at 04:27 PM.
Nov 10, 2012, 04:37 PM
flyin' fool
goldguy's Avatar
AndyGadget:

Polyhedral. Good fix. Glad you got it performing.

Frank
Nov 10, 2012, 04:53 PM
Registered User
Terry Rigden's Avatar
Quote:
Originally Posted by goldguy View Post
I don't think 'scale effect' plays a roll here, just differences in building, setup, materials and personal CofG tastes. I'm flying my indoor at almost 40%, but I'm flying it all the time, no gliding going on. Right now I've got three in different sizes, all maidened at 25% and none are anyway near each other in CG location, but all rearward, not forward. That's because I'm interested extreme flying and not interested at all in how it glides.
That's interesting, I normally fly other aircraft with a rearward CG but on this one at 25% it was so twitchy to be almost unflyable. I did some dive tests and found that I had to move the CG forward to 20% to get it to be neutrally stable.

I've also noticed that at low speed it gets into a dutch roll rocking and rolling back and forth. I seem to recall that on a normal model that indicates either too much fin and rudder area for the dihedral or too little I can't remember which.

Mine dives in right turns , I think this may be a gyroscopic effect mad worse by the prop being 1/2 of the span.

Don't get me wrong I'm really enjoying flying this model, it's ideal for the rough and tumble of a crowded indoor session and its great for calm mornings outside our house.

Regards

Terry
Nov 10, 2012, 10:20 PM
Registered User
Quote:
Originally Posted by goldguy View Post
AndyGadget:

Polyhedral. Good fix. Glad you got it performing.

Frank
Definitely polyhedral. (No, you can't drag me back into that one, Frank )

Although Gadget's post, and the subsequent reminder of our little 'hedral debate last spring has got me thinking about a curved wing nutball.

Hmmm... Infinite-hedral. I wonder how various mathematical curves would perform: ellipse, arc, etc....

Don
Last edited by Kalkan; Nov 10, 2012 at 10:26 PM.
Nov 11, 2012, 12:15 AM
Registered User
PyroMan's Avatar
A curved wing, now that would be pretty interesting. You should build one, I'd really like to know how that would work out.
Nov 11, 2012, 07:34 AM
What goes up . . . Damn trees!
Quote:
Originally Posted by Kalkan View Post
Definitely polyhedral. (No, you can't drag me back into that one, Frank )
Don
I missed that, but thinking more about my Nutball, I'd now be tempted to call it more of a bidihedral.

Andy.

(Trouble is, cutting foam is addictive. I don't build often, but I'll be building soon.)
Nov 11, 2012, 05:48 PM
Registered User
RTHawk's Avatar
Goldguy: What thickness did you use on the fifteen incher and hotglue or foam safe. Started a fifteen inch out of FFF and the complete fuse foam weighs 32g with no landing gear. Love this design have built several larger ones over the years but trying to get this one to fly in a small gym, standard basketball court with no bleachers on sides. I agree that light is might for close quarters.

RT
Last edited by RTHawk; Nov 11, 2012 at 06:18 PM. Reason: wording


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