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        Li-poly for 1.5-2.0 amps (Wal-mart sky surfer)

#1 jms336 Sep 20, 2003 12:15 PM

Li-poly for 1.5-2.0 amps (Wal-mart sky surfer)
 
1 Attachment(s)
I have another thread over in parkflyers on my $18, 26", 2.0 oz
wal-mart sky surfer. It is controlled by differential thrust.

http://www.rcgroups.com/forums/showt...40#post1314640

Stock battery is 3-cell 200 mah nimh weighing about 0.4 oz.

The plane will only climb on the very top of the pack, so I would like to put a bit more kick in the pants with a single lipo.

I checked the amp draw and it is 1.5 at about 3.4 volts. I would guess less than 2.0 amps at 3.7 volts. What is the best li-poly in the 0.4 oz weight class to support this draw? I tried a 830 qualcomm, but it was too heavy at about 1 oz.

Also, any ideas on how to make a RFFS conversion from this plane are welcome. I have no RFFS experience. Maybe I should start another thread here in indoor.

Thanks, John

#2 AndyOne Sep 21, 2003 06:39 AM

John,

The best Li-poly is the Kokam 340mAh capable of 6.8A, it only weighs 0.32Oz

Andy.

#3 Thatovalguy Sep 21, 2003 07:36 AM

John, I second Andyone, get yourself a 340 pack, you'll have what you need. You might even try a 600 kokams, its only a tenth and change heavier.

#4 Dan Leonard Sep 22, 2003 12:14 AM

I bought one of these today and I think the best battery would be the E-Tec 250. Longer flight time then the NiMH but 1/2 the weight. And it will fit right in where the other batteries fit without mods.
Thanks
Dan

#5 jms336 Sep 22, 2003 08:29 AM

Let me know how yours flies Dan. Mine will not really climb, but will achieve level flight on the top of the pack. Only good for a minute or so before it becomes underpowered.

I am doing a mod right now to make it a pusher. I suspect that the prop position in the middle of the wing was destroying much of the lift. Probably not giving the best thrust either.

I reversed my polarities on the motors and put the prop on "backwards" haven't had a chance to fly it yet. I'll close up the stock prop holes in the wing with tape to restore the wing's lifting ability.

I moved the rx to the rear of the compartment and am going to put a 850 Li pO (lightest I have)
(0.6 oz) to the front. Should balance at stock point more or less. I probably gained 0.2 oz or less, as I have removed the on/off switch and fuse bottom and some tape.

I was going to take off the foam fuse but it really serves a structual function keeping the wing from folding.

John


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