I should've worded that different. The proper CG for it to fly at its best will remain
the same on the jet. Adding the heavier battery will upset that balance and make
it nose heavy. I would try the original AA lipo, at least until you get it flying right.
It's more than enough to power the N20's.

I'm not speaking from much experience, but if I had to choose from putting weight above or below, I would say you would find more overall stability suspending battery weight below mid-wing rather than stacking it on top. I've been working toward low speed pendulum-like design but an inverted pendulum like weight above the wing would be, doesn't sound all that stable (though there isn't alot of difference there in the aa jet). The way the jet wants to dive when it loses lift, the weight on top might send you plummeting straight down. Good luck in your tests!
John

yeah, you're right. Picture a hang glider where the guy stands on top
of the wing instead of hanging below it. You're pushing down on the wing
instead of pulling it. Same as pushing a wheel barrow vs. pulling it. Much
easier to pull it.
Also I've found that keeping the motor, RX & lipo as close to the CG as
possible makes the plane more stable.
Having the motors at one far end and the RX & lipo at the other far end
causes a teeter totter effect which increases porpoising.

I was just at TRU and they had a HELIX made by Air Hogs. I have never seen this before, does anyone know anything about it. It uses a 3.7 lipo @ 300 mha.I wonder I could use this battery in my AA? I think the stock batt. is rated at 160 mha. Well it was to neat to pass up , I had to have it. Besides it was the only one they had and at $ 59.99 it was worth a try, I can always take it back. I went there looking for a Storm Launcher , NO LUCK, they had some type of land and air NO WATER R/C that seems to marketed at the SL. It also used a lipo battery but its rated at 7.2v and comes w/ charger.

I've heard the forward speed on them is real slow. I can't get a good picture of it, but if you can cut the rings off those little props I'd bet you'd get a lot more forward speed out of it.

I found some info ( Mods ) on the Helix: Take the canopy off, moving battery back 10 mm, taking out screws and trimming plastic is all I could find.Stock weight is 54 grams.May be able to get it down to about 50 grams. I can't wait to it try at home, not enough room in my cube. I need to get lights on it first thing. well maybe I should get use to it first. It seems to hover fairly well. What a neat little toy! I was wondering if anyone knows if the wall charger will work on AA..

What's the mah rating on the charger?

5.5v 280mha 120v 60Hz 7w is what is on the charger.

My guess is that it charges the 300mah lipo at near 1C. It would probably cook your AA lipo. It may swell, explode (you'll hear a loud whistling noise first), and then catch on fire. LiPo's burn at about 2000° F. The hottest part of a good camp fire, near the coals where you can melt a beer can, is about 800° F. Of course, it's up to you whether you want to try it or not, but my suggestion would be not to.

Gtx, what is 1c?

Djstinger, the heat that is created by a lipo destruction, as described by GTX, is equal to willie pete. I am not old enough, nor young enough to see WP in action. I have had training in how to deal with it. Dj if you overcharge or use an untested charging device. Your home could easily burn down. If you live in an apartment structure, it will burn down. Please follow the charging instructions for your model. Please do not mix chargers. I'll try to go back and find the pic's of homes burned out due to improper charging of LiPOs. I lost my train of thought there, GTX says the heat from a lipo is 2000 degrees. A fire in the fireplace is less than 600 degrees, when you light a piece of paper it is 460 degrees. My forge is about 1500 degrees, that is for forming steel. My Plasma Cutter may get to the 2000 degree level, but it is a controled operation. If I sound to strident about being careful I apologize.

one of the motors on my AA keeps coming loose from the stick glue. any suggestions on how to make it adhere better?

more info on the Helix: http://www.rcuniverse.com/forum/m_4599870/tm.htm

i like it a lot, the thrust on mine is pleanty, it'll get up to a pretty quick pace if it starts getting out of controll, but its fun.

nick

Frank10;

No problem.
1st rub your finger or thumb across the grey mount and on the wing. Remove the rubbery stuff....
Use clear double sided carpet tape and it will go right back on. The flat on the mount is sometimes cupped. It can be sanded or filed flat or use more than 1 layer of the clear tape so you get full contact.
They make a white foam carpet tape. It doesn't hold. Go with the clear.

Tony
ARS Software & Innovative Solutions
http://www.falcon1.net/~ars/rcmodels.html

1 x Current rating. LiPo battery specs include the voltage (which is 3.7v nominal and 4.2v fully charged per cell), the mAh rating and a C rating. The C rating is expressed as a multiplier number times the mAh rating. For example, our new SuperPack1300 for micro helis is a 2 cell LiPo pack. 2 cells run in Series and none in Parallel, so it's designated as a 2S1P pack. That's 7.4v (always use nominal), 1300mAh and it's rated at 14C continuous and 16C burst. The C rating is how fast you can discharge the battery, or how much current you can draw through it without harming it. In this case it's 14 x 1.3A, or 18.2Ah. If you drain more than that (which isn't possible with the motors in a micro heli), the battery would heat up and not be able to keep up with demand. The heli would no longer have the power to continue lift, so you'd have to land. You could wait a few seconds and actually fly again for a little while, but the cycle would repeat. You'd lose lift again as the battery couldn't keep up with demand. It's not a good idea to do this.

On the flip side, LiPo packs should never be charged at more than 1C, regardless of the battery C rating. In the case of our SuperPack1300, that would be 1300ma, or 1.3A. However, our tests show that you can get a much longer lifespan out of a LiPo if you charge at less than 1C, like .8C, and possibly even greater lifespan if you charge at even less. I charge them at 800ma (.8A). LiPo chargers use the cc/cv (constant current/constant voltage) technique, and since the first stage (cc) is the fastest, charging at 800ma doesn't really take that much longer.

Was this too much info?

One of the things that is not taken into account with the C rating is the batteries internal resistance. This may get a little deep but I'll try anyway.

Every battery has an internal resistance, when you draw current out of the battery the voltage drops besause of this internal resistance. A battery with a high C rating like SlotCars 14C batteries have a very low internal resistance. So when you draw 14C worth of current you still get 7volts (an estimate) with a charged 2S pack.

Batteries with low C ratings like 8C and some of the cheap LiPo's have a higher internal resistance, which when loaded to 8C may only give you 6.6volts (an estimate) with a charged 2S pack.

The lower voltage reduces the motor speed, so you give it more throttle and the battery runs flat sooner. The internal resistance also creates heat in the battery, which is why you shouldn't discharge a LiPo at greater than its recomended maximum or you'll get to see for real what all the fuss is about (boom).

LOL. Along with the "boom" theme, I suppose we should warn them about not poking a knife blade through them when they open their AA's up.

I will try that. Is that something they would have at home depot or lowes?

Yes (to the tape, not your finger).

Hi All;

Just an observation.
All the new small rc stuff has lipos in them. Most advertize For 8-12yrs old and up. What kids that never found areas like this forum isn't going to open his up to see if a wire broke..ect...when it does eventually quit?
Yet, it's just the standard warning that we've all gotten used to. I doubt they will use care or know where to start, so out the knife/fork comes!
I don't want to see lipos go away! But I'd think the liability issues would be enormous.

On the charger for the AA.......Radio Shack has a 9v 450-500ma that works well. Instructions for installation are on the AA Toolbox at www.aatoolbox.no-ip.org . (RacerX208's site)

The AA lipo is 135ma and charges in 20 min. Thats just under 3C. But.......it also has a shutdown circuit at 2.9v so it never gets fully discharged. Lipos should never be ran till dead. Some will recover, some won't. I measured some of mine and they will start out over 300maH charge, but drops off very quickly. Never noticed any heat or hear of people with dying AA lipos. Dedicated chargers should be set to take this into account.

Just some thoughts.

Tony
ARS Software & Innovative Solutions
http://www.falcon1.net/~ars/rcmodels.html

All of those warning stickers do pretty well at limiting liability.

Thank you for all of the info ( TMI ) on lipo's or should I say warnings. I would never do anything to harm my AA or my family. The charger does plug right into the AA charging socket . This little HELIX is a blast, brings back memories of a few months ago when I got my 1st AA...

Okay now I'm getting alarmed. I'm putting some work into a plane with aa rx/tx and stock lipo, but with n20 motors/bigger props. I'm certain this is going to draw more current than the stock aa motor/prop combo, probably way more, it was enough to roast one of my mosfets on the original rx. Do I need a flack jacket or welding mask for this test? I will have to video record the first flight, if it explodes i want something to show for it!

what about using hot glue to attach it? i've got plenty of that

thank you for all of your suggestion to have the proper cg on my jet.
why i use i bigger lipo is only because it's what i have here, also i put it on top of the fuse ('cause it can't be inside, to big) to protect it from landing...

does anybody knows what is the weight of a stock aa jet?
i'll send a pic how it's mounted.

I posted that jet mod on the "New Spin Master Jet" forum and that stock AA
jet was 21.2 grams.

About those lipos, they pack a punch!
Crossing the wires on one taught me that right quick!
I now store them in a fire proof metal lock box. If that would even help.

Anyone thought that when someone forgets about their plane and leaves it in
closet for a few years that the lipo won't slowly discharge itself to a dangerous
level? Also how do you dispose of a bad lipo? Seems dangerous sitting in a
landfill. I know car batteries are to be taken in and properly disposed of.