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Old Oct 12, 2005, 08:37 PM
Look out for my plane!
Michigan
Joined Sep 2005
432 Posts
I flew! I flew! I really flew!

Well I finally flew today. I created a flying wing (Mugi) using a 400 motor and (2) 7 cell 600mAh NIMH's. Had some trouble at first because the area I was at was surrounded by some trees that "grabbed" it a few times. I finally went to a more open area and had a much better time. I was able to go back and forth about 50' in the air with very few problems!! Hurray!!!!

However there are a few things I have questions about.

1. Going full throttle I only seemed to get around a 3 minute flight with with each 600 mAh pack. Does that sound about right? I have some 8 cell 1100mAh NIMH's but they are still getting broke in so I wont be able to use them as a comparison until tomorrow.

2. I have a 30amp ESC and when I put one of the 8 cell packs in and put it full throttle I could hear the motor go faster.. however, it seemed to "sputter" at full throttle - almost like the prop was slipping or something but it was tight so I do not think that was it. Any thoughts on what that could have been? After the battery ran for a bit it stopped doing it - almost like it slowed down some maybe? I was using a 6x3.5 prop at the time (I believe) so maybe it was pulling to many amps and my ESC was cutting out but that seems hard to believe with a 30 amp ESC?

3. What is the best way to increase flight time besides LiPo's? Brushless? Larger packs? Something else? I would like to get around a 10 minute flight at least if possible.

Thanks!
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Old Oct 13, 2005, 11:40 AM
Live to ride... and fly!
Tres Wright's Avatar
Forney, TX
Joined Mar 2002
15,165 Posts
7 cells isn't much for a 400 motor, but if it's flying to your satisfaction then stick with it. Normally with a 400 on a flying wing you go 8 cell Nicad or 9-10 cell NiMH.

Not sure what cells you're running, but most 600 NiMH cells are not good for much amp draw. You should get a little more run time than that, they're probably being pushed to their limit.

The motor sputtering, do you have any loose tape/ covering around the motor area?

Increasing flight time- the 1100 packs should get you to around 10 minutes of flight time. As for brushless, it really depends on what motor. Some will net much better performance at reduced flight time. Others will give about stock performance but increase the run time. There are a zillion brushless motors out there and each is unique
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Old Oct 13, 2005, 11:51 AM
Oldie but goodie
Popsflyer's Avatar
United States, CA, Orange
Joined Jun 2003
3,890 Posts
The 6x3.5 should actually work very well. I find they provide decent thrust with a little less speed at lower amps over the more common Zagi 5x5 used in S-400 applications.

Not sure about the sputtering. There is simply no way you are going to pull 30A on a S-400 motor and have it live for more than a few seconds.

I agree with 'Tres' on the battery recommendations.
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Old Oct 13, 2005, 03:13 PM
Look out for my plane!
Michigan
Joined Sep 2005
432 Posts
Quote:
Originally Posted by Tres Wright
The motor sputtering, do you have any loose tape/ covering around the motor area?
mmm.. Might have been.. I will retape to see if that clears it up.. I have heard about cutting out a small section around the motor to "quiet" it down some.. could that have something to do with it - I have a completely flat back end on the wing.
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Old Oct 13, 2005, 03:14 PM
Look out for my plane!
Michigan
Joined Sep 2005
432 Posts
Quote:
Originally Posted by Popsracer
Not sure about the sputtering. There is simply no way you are going to pull 30A on a S-400 motor and have it live for more than a few seconds.
So pretty much the motor will die before the ESC cuts out then? If so then that would be awsome - that is why I went with a larger ESC to begin with.. Motor = cheap, ESC = not so cheap.
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Old Oct 13, 2005, 03:18 PM
Look out for my plane!
Michigan
Joined Sep 2005
432 Posts
Quote:
Originally Posted by Popsracer
The 6x3.5 should actually work very well. I find they provide decent thrust with a little less speed at lower amps over the more common Zagi 5x5 used in S-400 applications.
How does that work exactly.. if I pull lower amps I will have longer flight times? So it is better to go with the largest prop you can run, as long as the speed is ok, so you get longer flight times? It sounds correct to me but 'ey.. "I'm a newbie"!
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Old Oct 13, 2005, 03:37 PM
WAA pilot #21
Vanning's Avatar
Princeton NJ
Joined Dec 2003
3,166 Posts
If you use less amps, you will run longer. Just like a car using gasoline. Go easy on the pedal and you can go further.

In order to use less amps, you need to do any or all of these:
A; use a more efficient motor (like a brushless) or
B; use a SMALLER prop (or less pitch). The bigger or steeper the prop is, the harder the motor hasta work to spin it, so it sucks more amps. Some props are more efficient than others too. The GWS HD props seem noticeably better than the slo-flyer ones given the couple that ive tried.
C; dont run at full throttle all the time.
D; reduce weight or drag on the plane.

Theres a few other things like tweaking your gear ratio/vs prop size, but thats kinda beyond what your looking for.
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Old Oct 13, 2005, 05:11 PM
Look out for my plane!
Michigan
Joined Sep 2005
432 Posts
Still have not been able to find out why it is sputtering.. I took it out again today and both 8 cell packs did the sputter at full throttle.. It is about a 1 second interval : run, sput, run sput, run sput..... and it looked like the prop actually slowed down when it sputtered.. retaped the back end around the motor too.. hmm.. very strange.. it also seems to have less power when it is sputtering as well....almost less then the 7 cell pack.
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Old Oct 13, 2005, 05:19 PM
Lands in Trees
Charlotte, NC
Joined Sep 2005
120 Posts
You should check to see if the sputtering doesn't coincide with glitching on the other channels. I had some sputtering too, and that was clearly due to glitching caused by arcing in the motor.
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Old Oct 13, 2005, 05:51 PM
Look out for my plane!
Michigan
Joined Sep 2005
432 Posts
Quote:
Originally Posted by treelander
You should check to see if the sputtering doesn't coincide with glitching on the other channels. I had some sputtering too, and that was clearly due to glitching caused by arcing in the motor.
Does arcing increase with RPM's (aka 8 cell vs. 7 cell pack)? I thought the motor had a cap in it but maybe it doesn't.. I will check to see anyway!
Thanks
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Old Oct 13, 2005, 07:39 PM
Oldie but goodie
Popsflyer's Avatar
United States, CA, Orange
Joined Jun 2003
3,890 Posts
Everything else being the same, Yes higher voltage = higher amp draw and more arcing. A larger load (prop) will also increase arcing at the same battery voltage.

Depending on your motor, it may or may not have any supression Capacitors installed from the factory. Minimum should be one soldered at each pole, then the two remaining leads twisted together and soldered to the motor case.
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