FT Duster and 10 x 4.7 prop - Motor Burns Up

[TexasPilot71]

Hi guys! And HELP!!

I built the FT Duster using the speed build kit and the power package PROVIDED BY FLITE TEST. This power package includes the EMax 2215/9 motor and a 10 x 4.7 prop. I know Flite Test calls for a 9x6 prop, but this power package was provided by Flite Test and included the larger prop. Additionally, the website specs show it should work with a 10 x 4.7 prop http://www.emaxmodel.com/views.asp?hw_id=16

However, the motor gets extremely hot after only a minute, smells like it's burning, heats the battery up, and depletes the battery in a matter of about 3 minutes. I've tried a couple different brand 1300 mAh 30C batteries with the same result. I even purchased another identical motor believing the motor was bad. SAME RESULT.

I am very frustrated and don't understand why it's doing this. The only think I haven't changed out is the ESC, but I doubt that's the problem. By the way, it swings an 8 inch prop no problem. I don't have the 9 inch to test.

Can anybody help? Thank you!

Attached photo shows watt meter after either 1.5 minutes or 2 minutes, I believe [URL=http://s287.photobucket.com/user/ZippinZim/media/Mobile%20Uploads/2015-05/20150504_151641.jpg.html] [/URL]

 

[endfim72]

Sounds like we are in the same boat. It seems something is amiss with the latest batch of power packs.
Here's my post I made today.
http://forum.flitetest.com/showthread.php?18449-Power-Pack-C-OVERHEATING!

 

[TexasPilot71]

Wow, interesting! The only difference between you and I is that my battery was very warm. I had the same sudden decline in power while flying and "plopped" it in. Also, my bench testing was at full power. Not sure if that's a poor way to test.

 

[endfim72]

According to the ESC documentation, it has an overheating safety feature that slowly kills the power. It likely saved our electronics, but I think it caused a receiver brown out and nearly wrecked my plane. Better the plane to take the brunt of the damage I suppose. I bought a 10x6 prop today. It should draw fewer amps according to the EMAX website. I'll bench test it tonight. I don't have a watt meter, so I'll just check the temperature by hand. I wish I would have picked up some 9" props too. Maybe someone from FT will ring in on this one and grab a sample from the stock room.

I wonder where we go from here?

 

[arizona98tj]

If it swings an 8" prop just fine, then why even continue messing with the 10" prop? I understand that it came in the box of parts, but you already know it is an issue so save it for another motor/build and go fly the 8" prop.

 

[TexasPilot71]

Good point. Here's some feedback I just received over on a facebook thread about it:
chances are the bogus chart that Emax has provided is not giving you or flight test the correct information. In addition, you don't understand the amp draw versus battery capacity formula. A 1300 Mah battery will only run for 6 minutes at 13 amps. You are pulling way more than 13 amps, so the 4 minute run time seems about right. I'll try to explain the formula. A 1300 milli amp hour battery is actully 1.3 Amp hours. That means that the battery can supply 1.3 amps for a whole hour. If you are pulling 10 times that, or 13 amps, the battery will only be able to supply that 13 amps for 1/10th of an hour, or 6 minutes. If you are pulling 23 amps, the battery can only supply that for 3 minutes. Many airplane manufacturers spec their epuipment to have incredible performance, but it comes at the cost of equipment longevity and run time. A motor that pulls around 20 amps should be powered by a 2200 Mah battery in order to get around 7 minutes of flight, but then the "all up weight" of the airplane increases, and flight quality decreases. There is also one other aspect that I have not personaly experienced, but have seen described on several threads. Altitude from sea level effects the density of the air. At lower levels the air is more dense, and causes a higher amp draw than it would at a higher altitude. If the guys at flight test are flying off of a field that's at a higher altitude, the prop that works for them might be too big for you.

 

[AkimboGlueGuns]

Go with a 9x4.7 prop. It should provide about the same amount of power, but the decrease in size won't kill your motor. I've burned up a few by over propping and it sounds like this is the problem that people have been having.

 

[endfim72]

I tried the 10x6 tonight and got the same result. It took a little longer and a tad more throttle to get the same undesired results. It looks like we have to go the route that akimbo suggests. If the chart is indeed bogus, as it appears to be, I hope our experience changes what they ship out. It might be best to post a review on the product, but I want to find the right prop for the motor before posting.

 

[BigWave]

I was having this problem with my Duster when flying it nose heavy. It was too nose heavy. I got it balanced to be just baaaarely nose heavy and it has no issues. I found this by comparing to my sons Duster with identical setup other than balance.

It was going through the battery much faster and hotter. We both use the same motor/esc/battery/prop. It was making a huge difference.

 

[TexasPilot71]

Thanks, BigWave. My CG is just that...baaaarely nose heavy. I don't think that's the issue. But I appreciate the feedback!

 

[makattack]

I'm running an EMAX GT2210/11 with a 9x4.7 prop on a 3S 3300/25C battery with a 30A ESC, and while static trust tests at max throttle only draws about 19A, it's definitely at the limit of the motor. Even when running it for about a minute at 50% throttle which gives me about a 10A draw, the motor gets too hot to touch if it's a static run (indoors, plane held down). When I fly it outside, I can run 50-70% throttle, for about the same time, land and touch the motor which is at most slightly warm.

The airflow over the motor in flight makes a big difference.

Oh, I have the motor mounted on a FT Blunt Nose Versa Wing in a pusher configuration.

 

[schrodingerslapdog]

Have you contacted Flite Test's support? They will stand behind their product offerings. I have consistently run my power pack C on 10x4.5 and 10x4.7 props with no problem. If there's a problem, they need and want to know.

 

[TexasPilot71]

Have you contacted Flite Test's support? They will stand behind their product offerings. I have consistently run my power pack C on 10x4.5 and 10x4.7 props with no problem. If there's a problem, they need and want to know.

I did a couple days ago. No response yet.

 

[BigWave]

Hope you get it sorted out soon. We run the Alttitude Hobbies power pack with a Suppo 2217 and 30 amp ESC. It handles the 9x4.7 or 9.6 fine. The Duster flies great with either prop. The motor and battery are barely warm after flying with this setup.

 

[TexasPilot71]

Flite Test wrote me back and basically said "ours runs fine" and "good luck". It was a professional email and I don't have any issue with it. I think I'll just try the 9x6 and see how it goes. Bench test looked good. I think it's just under-sized to run the 10 x 4.7 prop at high power settings.

 

[endfim72]

The response they gave you is a little disappointing. I tried a 9 x 4.7 with mine. I experienced the same results of overheating and a funny smell at half throttle within about a minute. Sounds like yours will at least swing some friendlier props, so it's not a total loss.

On another note, have you checked the timing on your ESC. I've been doing some reading on that today. The BLHELI should default to medium timing. If for some reason it was on high, that might explain your results. I don't think low timing would be an option based on the number of poles the motor has, but someone with more experience may chime in with difference experiences. After what I've learned about the different ESC settings today, I'm thinking that would be a great article or FT show to cover the different settings.