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Old Feb 10, 2004, 08:42 PM
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Need some advice on making my Mega scream...

I completed my 75% Ridge Runt, converted for speed to spice things up in the fleet. I figured that my Mega 3 turn would be the ticket as I have run one on NiMh 1700's with great results. Here, the Runt is smaller so I went with a 7 cell 1100 NiMh pack and it was, in a word, wimpy. I thought that it needed another cell so I tried the 8 cell version. Still wimpy compared to the 1700 pack. Also, the packs have been cycled 3 times so far. What do I nned to make this thing move and not have to install a 1700 brick in my Runt?
Thanks in advance...
Kip
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Old Feb 10, 2004, 09:20 PM
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Newcastle, Australia
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What prop are you running, we need to know a current draw, that may be the problem with those little nimhs

Grant
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Old Feb 10, 2004, 09:26 PM
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I've had the Graupner 4.75 and 5.2 speed props on. I'll get with my friend with the amp-meter. Yeah, it's the AA's vs. the 2/3 AA's also...
Thanks,
Kip
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Old Feb 10, 2004, 09:27 PM
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Newcastle, Australia
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Kip,
Just had a quick look around and I can't see those packs providing much more than 10-15A, a 3 turn mega will want a bit more than that, say 20-25A if proped for high performance. So maybe try the 1700's

Grant

PS I've never owned a nimh pack so I may be wrong.
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Old Feb 10, 2004, 10:24 PM
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Grant, is it the norm to run such large batts in small racer-types? I'll gladly trade weight for duration here. My 1700's will run for 6-7 minutes. The same rpm for 3-4 minutes would be ideal.

Kip
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Old Feb 11, 2004, 07:14 AM
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England
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I use the 3 turn with a 4.75x4.75 prop on 10 x CP1300's and the current draw on the ground is around 32-34 amps. I get just over 3 minutes full throttle. Its about the limit for the mega, if you ran any higher capacity cells for longer than that you will fry it.

Regards
Kyri
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Old Feb 11, 2004, 07:19 AM
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8-9 1700 aup's run a 3t with a 5.2x5.2 right at 30 amps --perfect!
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Old Feb 11, 2004, 08:57 AM
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Concord, MA
Joined Jun 2002
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You are running HE 1100 cells at way over what they are capable of ampere output wise. Get some better batteries. Try the KAN1050 or 1300 ones. The HE will put out less amps, and you want ampos if you want performance, not just milliamp-hours. The KAN 1050 maybe good for 15 continuous and the 1300 are aa sized 1 oz and maybe 20 amps continuous. The CP1300 nicads would be a good choice or the 1700AUP which are maybe good for 25-30 amps and a little over an ounce each.

These guys who are telling you to keep the weight down are being unrealistic. If you want to go fast, a high wing loading is not such a bad thing.
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Old Feb 11, 2004, 05:24 PM
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Thanks BEA flyer and everyone else. A friend of mine has some KANs to try...
Kip
http://www.springeraviation.net/
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Old Feb 12, 2004, 02:22 PM
luc
I plant balsa sticks too
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France
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I have 4 mega 3 turn (3 more to come) all on 3S lipo.
3S2P Irate 1100 and 4.7*4.2 is a very fast setup and not that expensive. Obviously, very light. You will not recognize your plane....
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Last edited by luc; Feb 12, 2004 at 02:39 PM.
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Old Feb 12, 2004, 02:35 PM
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Sterling hts, Michigan
Joined Jun 2003
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I am running my 3 turn on 3s2p kok 1500. About 7.5 oz's for the pack. Give's 6 min's of motor and 300watt's.
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Old Feb 12, 2004, 02:36 PM
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Atlanta Hartsfield, Georgia, United States
Joined Apr 2002
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Where are you?

is that the Atlanta EFlyer's field? It looks big and grassy. I need to come fly with you guys. Do tell.

I think the smallest battery that will run that 3 turn well will be the 1700 AUP NiMh, or the 1950 FAUPs . Kan950/1050 will be good for at the max about 16 amps. I don't imagine that you would pull much more than that in the air though. On the ground will be much more. Get a good flight time measurement with your 1700's for a full throttle flight, and calculate your inflight amp draw based on how much you take out of the packs. You'll be surprised how low it may be. The KANs may just be enough.

~~fred francis
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Old Feb 12, 2004, 02:42 PM
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United States, GA, Suwanee
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Quote:
Originally posted by luc
I have 4 mega 3 turn (3 more to come) all on 3S lipo.
3S2P Irate 1100 and 4.7*4.2 is a very fast setup and not that expensive. Obviously, very light. You will not recognize your plane....
luc, do you know what the amp draw is on that setup?
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Old Feb 12, 2004, 02:44 PM
luc
I plant balsa sticks too
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France
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around 25A static, 250W....I can't draw more on these cells. I have hotter setups (3S4P kok340 with 4.7*4.7 at close to 340W), but that's an expensive setup
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Old Feb 12, 2004, 08:06 PM
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Sorry, the field is the ATL RC Club. The "e" flyers fly wherever they will not be thrown out of...
Kip
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