14:20 with 7x700 Sanyo Twicell

I used to think that 7x250 NiCds are good enough as they give me 6+ mins of useful power. Now, after flying bigger helis for some time, 6 mins seemed a bit short. So I soldered together a 7x700 pack of Sanyo Twicells, charged it at 0.7A (730mAH) and gave it a try.

14:20 later I landed after a nice flight with only the last 90 secs in ground effect. That's 12:50 useable power - I am impressed.

Is this good enough for the records page?

WHAT!!!!!!!!
REALLY??????

I made a 7 x 720 mah Sanyo NiMh pack & only get 2:30 maybe 3:00 .

Why is this so????




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Regards,
John VHJM010700

[pgoelz]

Wow! That beats my brushless setup. I get a max of 12 minutes out of ground effect, and the norm is 11.

What is your total weight? I fly at 280 grams. I suspect you are somewhat lighter?



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Paul Goelz
pgoelz (at) eaglequest (dot) com
Piccolo web page: http://www.eaglequest.com/~pgoelz/piccolo1.html
Piccolo: AF010 brushless motor, 8 cell NiMh, stiffened and braced blades, modified swashplate

Paul,

my AUW with NiCds was 220g. I assume that the NiMHs add a few grams, so maybe 225 to 230. As I said, I'm flying 7 cells, not 8.

11-12 mins at 280g doesn't sound too bad either!

John,

Some possible reasons for the difference in duration:

My Pic is fully tuned and still much lighter than most. I made a quick test and found that a stock Piccolo will barely hover with 7 NiMHs. During the first few minutes after a fresh charge, voltage is high and you can get out of GE. Once the pack settles to its nominal voltage under load (around 8V) there is not enough power to get out of GE.

A stock Piccolo needs higher rpm and thus much more power to hover than mine, therefor the motor gets warmer, reducing efficiency further. And the batteries deliver less useful capacity at 3.5A than at 2.7A, so there is another hit on duration.

It all adds up pretty quickly, and the only solution is to increase efficiency (go brushless as Paul and others did, or tune your G295 motor) or put your Pic on a serious diet (as J did), or both.

If you want to compare, my Pic hovers at 1030 rpm (main) and 2750 rpm (tail) with carbon blades (less pitch than stock blades). Average current draw is 2.7A.

Maybe I should mention that my carbon blades where worn a little bit after hundreds of flights and I sanded off 5 mm at the tips, giving them a slightly different shape.

Finally, my Pic is statically and dynamically balanced (better than 0.05 grams), and tracking of the main blades is very accurate, which also saves energy.

As you can see, there's always room for improvement...

DUMB QUESTION:
What is a Twicell. And where can I get one. My local hoby shops barely carry 250 NMih cells or packs.

It's the product name for the Sanyo 700mAh NiMH cells. They are approx. the same size and weight as 250mAh NiCd cells.

Great time! It's only 30 sec less than I got on my Thoshiba 7x700, BUT I was in GE all the time.
Good to have you back in the race, I need some competition

It's up: http://home.swipnet.se/~w-53305/piccolorecords.html

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SE-XJL

Hubs and other mods And Flybar bearing mod

Where to buy?

I recently bought in bulk to assemble 7-cell and 8-cell packs for my Hornet (sorry !). I have some spare if anyone is interested - these are Sanyo 720 mah flat top cells (HR-AAAU).

See http://www.ezonemag.com/disc/Forum9/HTML/002604.html