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Dec 17, 2012, 06:38 AM
Lets break some props :D
joseico90's Avatar
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Cool

The Underball 24"


During the development of the Underball 14", demand for a bigger version for "standard" gear arose, so I made one, here it is.

-Another of my Nutball spin-offs, based on the Nutball wing, having so much vertical stabilizing area make it track superbly, especially stable on high alpha due to the bottom fin and rudder.

-It's VERY stable and easy to fly, it turns very well without diving much, handles some wind OK, and perhaps could be used as trainer, a friend from Greece is learning to fly with his. (see the UB 14" thread using link above for details)

-The prop in slot has its natural advantages too, the main ones being public safety and 's savings on props/motor damage. (I quite like its noise too)

The back end has plenty of foam so it MUST BE KEPT LIGHT to balance OK.

GEAR:

-Blue wonder 1300kv motor, 8x3.8 apc slow prop in pusher conf.
-10A ESC
-3s 800 mAh to 1300mAh batts
-Two 7grm servos or similar.

Even with the tape, paint and epoxy.. I ended up with a AUW of 307 grams, felt very light in the air and with the 3s 800 batt my CG ended up at around 30% (a bit rearward, but I like them this way)

My friend in Greece is flying his at 500 grams!! AUW (and he is a beginner)

UPDATE 20/01/13

Extra info added below
Last edited by joseico90; Jan 25, 2013 at 10:38 AM.
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Dec 17, 2012, 06:50 AM
Lets break some props :D
joseico90's Avatar
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maiden


New Underball 24" Maiden (6 min 29 sec)


Other people's UB 24's

Underball 24 (1 min 54 sec)


Underball 24 number two (3 min 52 sec)


Underball 24 with LED lights (0 min 50 sec)
Last edited by joseico90; Jan 25, 2013 at 10:35 AM.
Dec 17, 2012, 08:02 AM
Chris
I like...
May I suggest: remove the ` " ` from the title...

Does my 22.6" UB fall under this category? :P
Ok yes..
Dec 17, 2012, 09:05 AM
Lets break some props :D
joseico90's Avatar
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Oh yes you may suggest...
Dec 17, 2012, 09:24 AM
Chris
No, wait, I'm such a fool, the `"` means inches...
The mistake was in the 14" thread...
Dec 17, 2012, 09:48 AM
Lets break some props :D
joseico90's Avatar
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Quote:
Originally Posted by cmavr8
No, wait, I'm such a fool, the `"` means inches...
The mistake was in the 14" thread...
At the time I saw appropriate to call it Underball 14. No biggie.
Dec 17, 2012, 09:49 AM
Lets break some props :D
joseico90's Avatar
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anyway, you've got EPP now... great!
Dec 17, 2012, 11:42 AM
Chris
Here is the video!!!
17-Dec-12 Underball 23" day6 - IT FLEW WELL (4 min 52 sec)


The full flight video is 9:30 minutes! So I only kept the good parts...

Contents:
- flirting with birds...
- flying hands off for 30" and close-up shooting
- landing
- second take-off - motor burn!

Camera & sound effects: my (proud) dad

Still thinking about the motor burn... It might be over-amp draw, but this motor/prop/bat combo has been tested many times, often working at full throttle, whereas I only used 60% throttle now.

Maybe water from the plants got into sensitive electronics during the first landing and created a short somewhere in the motor... Due to the short too many amps were drawn and the motor windings's insulation was burnt, resulting in further shorts and high currents...

The battery took a small (electrical) hit as I found it to be at 4.1V /cell instead of 4.2. Will recheck its internal resistance and evaluate the motor later.
Dec 17, 2012, 12:05 PM
Lets break some props :D
joseico90's Avatar
Thread OP
congrats Chris..

Great video and image quality (what cam is it?)

Great to see you having fun at last, you thank me...but really your perseverance and willingness have brought you this far...well done.

And by trying to help you... we have developed a good, well mannered, highly tolerant model aeroplane.

I can just see you enjoying RC........A LOT



Next.. some high alpha..low level...flight practice..maybe with the next? lighter one. (EPP will be good for that :P)
Last edited by joseico90; Dec 17, 2012 at 12:10 PM.
Dec 17, 2012, 12:18 PM
Chris
Hehe...
the cam was shooting at 720p but since my dad is not very good at zooming I'll put it in 1080p mode for the next videos...

And maybe do digital zooming on editing if I really feel like spending a whole afternoon instead of building UBs (highly unlikely) :P

Got to start studying for my exams though...
Dec 17, 2012, 12:37 PM
Lets break some props :D
joseico90's Avatar
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great to have such a supportive dad...
Dec 17, 2012, 03:39 PM
Lets break some props :D
joseico90's Avatar
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hey...was that an on-board camera?
Dec 17, 2012, 03:58 PM
Chris
Haha you're observant...

Yes, on the second "flight", I though I could mount it, but the motor puffed so I just recorder the failed launch...

Next time
Dec 17, 2012, 04:03 PM
Lets break some props :D
joseico90's Avatar
Thread OP
shame, next time..hey good luck with the studies..
Dec 17, 2012, 04:54 PM
Chris
Thanks..

So, in this motor's specs, when they say
"Lipo Range: 2-3 cell
Suggested prop: 8x4 ~ 9x5"

They mean: "use 9x5 with a 2s OR 8x4 with a 3s"?

They do not mean "use a 9x5 or 8x4, with a 2s or 3s, mixed as you wish", do they?

Maybe that's why my motor burnt...


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