Temperature problem with HDX500 helicopter, need help

[Helikopter_Crusher]

Hi there,

I cracked my Kora 15-12 brushless motor on my HDX500 at the last crash and had to use that: http://www.helidirect.com/product_info.php?cPath=44_385&products_id=2802 brushless motor instead.

I tried everything from a 19 T pinion up to a 23 T pinion with different throttle settings and head speeds but I could not get the temperature of the motor lower than 158 F (70°C).

The temperatur was taken after 5 minutes of hovering with a 4s battery and a jazz 80-6-18 at 50, 60, 70 and 80% throttle.

Does anybody know that problem and can somehow help me to solve that problem ??

I want to use this motor not forever but till my kora 15-12 is back I do not want to crash because of a overheated motor.

Thanks in advance for every help.

Michael

[falconea45]

Sounds like its just an inefficient motor, depends on number of turns and wire gauge + quality of the magnets etc

[LITHIUMSTATIC]

Seams like I heard that motor runs kind of toasty but handles it well.

[Helikopter_Crusher]

Here is the log from my last flight on July 1 ...

The yellow line is temperature in Celsius taken on the bottom of the motor where the 3 lines go into it.
The red line is the temperature of my cheap LiPo 4s 3200 mAh 25C battery.
The green line = voltage of the battery
The blue one = current

If I put my 4000 mAh Kokam battery in and do the whole 9 minute flight the temperature of the motor reaches 90° Celsius easy and rises for the next 2 minutes to a 110° Celsius after I switched of the motor.

Michael

[falconea45]

Temps will always rise when you stop as there is no longer any air passing over them thats why on board temp sensor/recording is so good(Eagletree).

[John Heli]

The motor you linked is known for its temperature problems on 4s. It is great on 6s because of better cooling using higher RPM. The only solution is a appropriate motor for 4s like the Kora again or swith to 6s using a 130 or 140 tooth main gear.

[falconea45]

JH this is why the Scorpion motors have different stator setups within the same model because you cannot get good efficiency across the whole range with the same setup. Most motors of a given model type just change the windings to get the required KV and the efficiency suffers in some, but scorpion get it right by changing the stator etc so good efficiency across the KV range

[John Heli]

You are right for sure. But the only thing is: The HDX500 is sold with a motor best fitting for 6s, but the recommended battery the delivered gear is for flying it on 4s. So either change the gear and battery or the motor.

[concept1]

so what other motors work well on 4s?

[John Heli]

The Kontronik Kora 15-10 or 15-12 works well, I fly the Hyperion H3025-10 which has enough power and the ultimate motor here in Germany is the new one from Strecker.