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Old Dec 07, 2003, 12:45 PM
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SS Flyer's Avatar
Greenville, South Carolina
Joined Oct 2003
109 Posts
Question
How much does cold air affect ROG

Being fairly new at RC flying, I was wondering how does air temperature affect taking off from ground? The reason I ask is, it was in the low fourties this morning and the Slow Stick seemed to struggle more than usual to gain altitude. It was calm for the most part with an occaional light breeze. Fresh charge in batteries. Stock setup. I always ROG. It just didn't seem to want to get off the ground this morning.

edit: Using nmh batteries.
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Old Dec 07, 2003, 01:01 PM
Master of the Wind
AIR MOVER's Avatar
TEXAS
Joined Jun 2001
3,044 Posts
what type batteries? lipoly cells sag in those temps.. not sure about nmh cells nicads dont seem to care..
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Old Dec 07, 2003, 01:06 PM
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Greenville, South Carolina
Joined Oct 2003
109 Posts
Air Mover,

Using 8.4 730mah nmh at present.
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Old Dec 07, 2003, 01:09 PM
I need a new plane STAT!!
DrBill's Avatar
Rhode Island
Joined Sep 2003
841 Posts
NiMH prefer a warm climate..if they were freshly charged they would perform well...if they had cooled the effects would be noticeable. I always put mine in my field charger for a few mins. before flight time in cold weather.
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Old Dec 07, 2003, 01:09 PM
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Dick Huang's Avatar
Dallas,TX, USA
Joined Mar 1999
834 Posts
SS Flyer,
The lower than standard temp(59F) at low 40's should enhance your ROG. If stand=0 ft, then 42F would be equiv to take-off at
-1000 ft; it's the high altitude problem in reverse! I recommend you look at your equipment to find the problem.

Dick Huang
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Old Dec 07, 2003, 01:26 PM
Registered User
Alexandria, MN
Joined Oct 2002
209 Posts
All things being equal, a plane gets more lift when the air temperature drops because the density of the air increases. However, lower temps cause your batteries to lose some kick. So you're probably experiencing a lower output from your motor. Keep your batteries warm until you put them in your plane and you may see an improvement. If you are using Li-poly's, that probably won't help; I know that my li-poly's do not last at AT ALL in colder weather - can't even get my plane back to the runway before the batteries are basically dead. Regards,

Kyle Sands <>< Huntley, MN
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Old Dec 07, 2003, 01:54 PM
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Greenville, South Carolina
Joined Oct 2003
109 Posts
Don't think it is a battery problem. They were taken right off the charger and were still warm. I have since looked at the motor and it seemed to make a noise indicative of needing lubricant. It sounded much better after some lubricant and was noticeably quieter. Haven't had a chance to fly it again to see if that was it because the wind increased.

The motor is only about a month and a half to two months old with mostly weekend flights on it. Usually fly for about 10 to 12 minutes each flight for about 2 to 3 hours. Could the motor be going that soon?
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Old Dec 07, 2003, 03:04 PM
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TooTall's Avatar
Home of the Toledo RC show
Joined Jul 2003
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If you are using the stock motor there is the chance it is time for a cleaning and lubrication......I keep my brushed motors "washed out" with Power Shot electric motor cleaner.....should be at your LHS ...the electric car area........I fly in Ohio and the temps have been in the 30's and 40's ....my biggest problem is keeping the lipolys warm......I charge them fresh at home and try to keep them warm in a soft cloth in a styro cooler..
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Old Dec 07, 2003, 03:06 PM
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New Bern, NC
Joined Mar 2001
3,050 Posts
Slow Stick

If that plane is what I think it is, then the batteries are hanging out in the breeze. Prop wash, plus the ambient temp. (40), will cool those cells down in a matter of seconds. In all probability it is the batteries. Try charging them till they are warm, and then wrap in a piece of foam to help keep the heat in, and then fly. I wrap a paper towel around mine in my Beaver and it helps. They need to be kept cool in the summer, and warm in the winter. If your aircraft has cooling vents for summer flying, tape them closed for the winter. Below 40, most of my packs, nicad or nimh, work poorly. If I charge and don't fly for a while, they go in my pocket to stay warm. Tom
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Old Dec 07, 2003, 07:59 PM
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Greenville, South Carolina
Joined Oct 2003
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Quote: "All things being equal, a plane gets more lift when the air temperature drops because the density of the air increases."

I was of the opinion that colder dense air should create more lift but like I said, being fairly new at this I thought I would ask. I will try it out again as soon as possible since I cleaned and lubricated the motor. I think that could have contributed to the problem since this is the first time I have had any problem with it. Also, the batteries may have gotten colder than I thought.

Thanks for the replies. E-Zone is great! You guys are very helpful
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Old Dec 12, 2003, 06:43 PM
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Greenville, South Carolina
Joined Oct 2003
109 Posts
Today was the first chance too try the Slow Stick again after cleaning and lubricating the motor. This time I charged the batteries and left them in the house until I was ready to use each pack. I switched each pack inside the house since I fly from behind my house. This time the SS worked like a champ again. I suppose the problem was a combination of a motor that needed cleaning and batteries that had cooled more than I thought. Anyway, we're back to normal here. Thanks guys.
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