Motor/ESC performance in hot weather

Hi everyone -

I was out at the field yesterday feeding my Mig addiction... :)

I blasted through 17 lipos yesterday, 7 with the camo Mig29 V4 and 10 with the white, blue and red Mig29 V3M3e3.  Luckily when I have the field to myself, I just fly, land, install new lipo, fly, land, repeat, so maybe 30 seconds between flights.  So this means I am pushing my gear pretty hard over the course of the time I am at the field.  Normally it is not a problem, but now that we are in the heat of the summer I have noticed a couple of things I need to keep an eye on.

Through comprehensive testing and experience, I have boiled down my two favorite parkjet motors to the Focal Price 2700 motor which I run with a 6x3 EMP prop and 40A ESC.  I started a thread on the RC Powers forum here if you want more detailed info http://www.rcpowers.com/community/threads/focal-price-2700-kv-parkjet-motor.15992/

http://www.focalprice.com/YO090X/A2212_2200KV_Outrunner_Brushless_Motor_for_Airplane.html

This motor is the one I used the most on the V3/V4 sized planes, it is relatively light, very powerful for it's size (36 oz of thrust on 3S) and very inexpensive, about $11 now I think.  With the 6x3 EMP prop, I have had planes up over 80 mph in speed runs with a 3S battery, but it is probably the amazing pop and acceleration it provides that I like the most for "hole shot" type acceleration and pop when doing certain aerobatic maneuvers.

The second motor I like for raw power and speed is the NTM Prop Drive 2700 motor from Hobby King http://hobbyking.com/hobbycity/store/uh_viewItem.asp?idproduct=21482

 combined with a 6x4 APC prop and 60A ESC.  For those days when I want to feel like I have a V8 hemi under the hood, I take a plane with the NTM (like the white, blue and red Mig above) to the field.  On 4S, I have had the M3V3e3 up to 109 mph, that is blinding speed for some foam and glue you built yourself... :)  If you buy this motor, ensure you buy the accessory pack or you won't be able to mount your prop... :/

http://hobbyking.com/hobbycity/store/uh_viewItem.asp?idproduct=16719

Anyway, back on topic... :)  Now that the heat of summer is here, I have been noticing a couple times that after about 3 flights in a row that the Focal Price motor and 40A ESC would act up occasionally.  The motor would skip a bit, like it was temporarily out of phase with the ESC or maybe the ESC was getting too warm.  After landing, the ESC was warm, but not hot, the motor however was pretty darn toasty.  Yesterday's temperature was not extreme for where some folks live, it was 27 C/81 F.  And it is not just this Focal Price motor in this particular plane, I have had the same issue in a couple of other motors.  

So, it is not a drastic thing that would cause me to stop using the motor, rather I just need to alter my flying habits a bit to adjust to the hotter weather when I am flying flight after flight.  Rather than taking more time between flights, I will fly about three flights, then switch to another plane as I always take two planes to the field with me.  This seems to work fine.  The motor still gets pretty warm at the end of the third flight, but no skipping or acting up, then after about 20 minutes of cooling off (I put the plane under the table in the shade to help with this), it is ready to go back in the air without problem.

The NTM on the other hand is just a beast... :)  I think I could run that motor til it was red hot (but then it would probably light my plane on fire... :( ) and it wouldn't skip a beat... :)

I've been having some really good luck with these batteries from HK, they have plenty of discharge amps for my NTMs have been working just awesome.  http://hobbyking.com/hobbycity/store/uh_viewItem.asp?idproduct=9942

When using them with my NTM motor yesterday in the heat, they came down a bit warm, but nothing to get really worried about and with the Focal Price motor, there was no difference in temperature after running them, so I am very happy with them.  I had been using Nanotech batteries for my NTM motors with 45-90C discharge http://hobbyking.com/hobbyking/store/__11951__Turnigy_nano_tech_2200mah_3S_45_90C_Lipo_Pack.html

and found them to be a huge disappointment, especially considering how much more expensive they are than the Zippy Flightmax batteries, so lesson learned, it will be a long time before I try Nanotech batteries again... :/  Some of them lasted maybe 200 cycles and now are starting to puff or have cells that discharge much faster than the other two... :(

So a great day at the field yesterday, lots of fun flying and reminded myself that when the temperatures start to creep up to adjust my flying habits accordingly!  Oh yes and as my Mom would say (rest her soul), use lots of sunscreen and stay hydrated... :)

Cheers,

Scott