iron eagel

Flying a 2.5 lb airframe on a HET 2W-23 using an CC Ice 100 set at medium timing this is the data off of the ESC with a 5X5.5 apc prop. Given this motor is rated at 58 amps at 850 watts I am pretty sure I can try the timing at the high or hard setting, opinions?

Dr Kiwi

If the motor runs well on low timing, why make it (perhaps) run badly on high timing?

If you want to push the motor harder, just increase prop size....I find it hard to believe that a 100g motor will be happy at anything approaching 850W... but it is your motor and if you push it too hard it is your $$$$. [the 3W/g "rule of thumb" would limit the motor to 300W.]

iron eagel

I did not know about the 3W/G guidelines thanks that is very useful!
A bit more background may help.
They (HET) rate it at 850 watts on a 5 cell they say this is nominal... I'm not sure if that is the continuous rating or not, I suspect that is actually peak specifications given the size and weight of the motor.
The motor case temp a minute or two after landing was 125 degrees (F), this was after about 30 seconds or so of low power flight before landing to allow for cool down.
Right now I am running it on a three cell 33ma battery. I have run this setup using a 6.5X5 apc with that prop I was drawing 935 watts max, peak current at 80 amps, with the rpm topping out at about 25,500 rpm.
I have tried to maximize the cooling for the motor in this setup, and it seems to work, I'd like to see if I can get a bit more speed before going to a higher cell count.
If you like to see the application for this motor view:

http://www.youtube.com/watch?v=LSvvgPOU8gI

I dropped it to a 5X5.5 because of a bent shaft from the first flight. I have considered using a 5.25X6.25 apc but was thinking of seeing if I can get a bit more rpm out of the present setup first...

cyclops2

You have a bent shaft ?

You wind it to 25,000 + rpms.

You are asking for a 911 stretcher job.

iron eagel

The bent shaft occurred during the maiden flight, and was due to a bad prop adapter. During the second flight with a APC 5X5.5 prop peak RPM was 29, 461 Rpm, the motor is supposed to take upwards of 45,000 Rpm...

cyclops2

Eagel

Did you REPLACE the bent shaft with a brand new straight one ?

If no. You will waste power & speed.

Until you put in a new shaft. You are still good for the 911 stretcher job by having the prop break up unexpectedly.

Your choice. Pick the safer one.

Rich

iron eagel

Cyclops,
Yes the shaft had to be replaced it was only a slight bend but as you pointed out it was a hazard. The new shaft cost $20 but was well worth the cost. It was a shame to damage it the first time out but there was really no choice.

My question was mostly directed at the electrical characteristics of the motor primary the timing setting.

Glacier Girl

My Feedback: (4)

As you advance the timing so too the amps will climb.

If you are looking for more rpms dropping down to the smaller prop would be better. The larger prop you were running was too much for the motor, even on medium timing.

You can go to high timing with a smaller prop, since you are only running a 3 cell pack.

120 degrees after a minute or so, and after a cooling down run, is not a good sign for your initial set up. That motor was hot when running, getting close to borderline magnet damage from the heat.

iron eagel

Thanks for the information.
What would you say is a good temperature range for after a 2-3 minute flight at speed?
Due to limitations in space I can't get that large of a pack for increased flight time, but the goal is speed no duration with this plane.
I know the hard timing will increase current draw, I was wondering if it will affect the RPM as well...

Dr Kiwi

The motor case temp a minute or two after landing was 125 degrees (F), this was after about 30 seconds or so of low power flight before landing to allow for cool down.

If the case was at 125F (even after a cool down) then the internals must have been almost smoking hot... the windings and magnets in an inrunner will always be far hotter than the case.

iron eagel

Thanks that pretty much cements the fact that a 6 inch diameter is too much of a load for this motor.
The 125 degree temp was using the 6 inch prop, I did not take a temp reading after the second flight as the motor had already survived the high amp flight.
Now I wish I had.

Is it true that higher cell counts keep the motor temp lower?

After some reading I am more confused then before. Doesn't the timing effected when the esc fired the pulse to the powered coils of the motor?
And with a harder/high setting it is much quicker or advanced?
I thought if you have a motor that's not overloaded with too large of a prop you can get it to spin faster by setting the timing hard? Given this motor is rated at 58 amps at 850 watts on five cells I had hoped to be able to try the timing at the high or hard setting on three cells with the 5X5.5 prop as both my wattage and current were way below the spec they quote.
For some reason I have it set in my mind that on a three cell either my wattage or current could be higher at the lower voltage and I'd be safe.