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Old Jul 17, 2011, 08:32 PM
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Livermore, CA
Joined Jan 2007
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I'm trying to post mortem the demise of my 71" slick.

http://www.rcgroups.com/forums/showp...ostcount=16556

after >50 flights with 8S on A50-12L and 18x8 xoar, I decided to try 6S and propped up to 19x10. Since this was the first flight I was careful to rebalance as a final check before flight. So, my wings were untightened enough to get a string around the wing tube. I think I forgot to tighten them up. static check showed 1700 watts and 75A static, reasonable.

I wasn't doing anything violent, couple of passes, harrier, slight hover to check out pullout throttle authority since on 8S I had 2900 watts @90A static.

flying mostly straight and level one wing came off. at the time I thought it slid off the tube but it did not rotate so now I'm thinking that the tube broke. Here are a couple of pics of the wing tube.

Both wings had the wing bolt still screwed into the wing, so either the side gave out, or the looseness of the wings set up an oscillation that pulled the bolts through the side or the wing tube broke. I'm not in the habit of checking wing tube for damage, but going forward I will.

comments? observations?

thanks,
tim
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Old Jul 17, 2011, 08:56 PM
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United States, CA, Hayward
Joined Aug 2004
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Originally Posted by Sukhoikid View Post
Castle ICE 85 and Hacker 50/12
they dont make an ice 85...they make a 85HV, a ice 100, and an ice 80hv, but no ice 85
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Old Jul 17, 2011, 09:38 PM
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Originally Posted by rcbirk21 View Post
they dont make an ice 85...they make a 85HV, a ice 100, and an ice 80hv, but no ice 85
maybe it is the ice 80 then. i forget...
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Old Jul 17, 2011, 09:59 PM
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Florida
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Originally Posted by Sukhoikid View Post
Funny thing is it was cooler today than last week and last week I ran a 20x10 wood xoar. It was running WAY too hot last week so I decided to switch to 19x8 apc that I had. ESC was running way cooler the first 3 flights I did. The batteries are 6s 5000 mah.

The motor is rough when you turn the prop. I think something may of happen to the motor in flight and the esc couldnt take it. I will open everything up this week to see what is up.
Interesting. My Scorpion 4025-16 just crapped out on me. I was pushing it way too hard, 2300 Watts on a Xoar 19x8 (rated for 2000 Watts max). The motor would come down extremely hot so I dropped it to an 18x8. Halfway through this flight the plane felt like it was losing power so I landed right as the motor was giving out. It ended up puffing one of the batteries and the prop was very hard to turn. I think it was a bearing that went out and caused a huge amount of heat through the powertrain. Throughout all of this my ESC was still ambient air temperature. I'm wondering if maybe your motor took a dump and then caused your ESC to eat it as well.
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Old Jul 17, 2011, 10:09 PM
I fly, therefore, I crash!!!
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San Jose, CA
Joined Jan 2008
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Originally Posted by Sukhoikid View Post
Funny thing is it was cooler today than last week and last week I ran a 20x10 wood xoar. It was running WAY too hot last week so I decided to switch to 19x8 apc that I had. ESC was running way cooler the first 3 flights I did. The batteries are 6s 5000 mah.

The motor is rough when you turn the prop. I think something may of happen to the motor in flight and the esc couldnt take it. I will open everything up this week to see what is up.
Did you check your watts/amps after changing the prop?? The APC probably drew as many or more amps than the Xoar. APC props are more "amp hungry" than Xoar props are.....

SteveT
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Old Jul 17, 2011, 10:51 PM
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Originally Posted by SteveTtoooo View Post
Did you check your watts/amps after changing the prop?? The APC probably drew as many or more amps than the Xoar. APC props are more "amp hungry" than Xoar props are.....

SteveT
Due to this being my first big electric I need to pick up a meter. But I only ran the xoar for four or so flights and notice it running very hot with it. The apc prop I had on was the same prop I had since maiden and gave me zero issues. Plus it runs cooler than the xoar. I wonderig if maybe I damaged the motor with the xoar and when I flew with the apc this weekend the motor kept getting worst....
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Old Jul 17, 2011, 10:52 PM
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Originally Posted by 94'325is View Post
Interesting. My Scorpion 4025-16 just crapped out on me. I was pushing it way too hard, 2300 Watts on a Xoar 19x8 (rated for 2000 Watts max). The motor would come down extremely hot so I dropped it to an 18x8. Halfway through this flight the plane felt like it was losing power so I landed right as the motor was giving out. It ended up puffing one of the batteries and the prop was very hard to turn. I think it was a bearing that went out and caused a huge amount of heat through the powertrain. Throughout all of this my ESC was still ambient air temperature. I'm wondering if maybe your motor took a dump and then caused your ESC to eat it as well.
I believe this may have happen.
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Old Jul 18, 2011, 12:32 AM
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Chicago
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The same thing happened to my trex 600 a few weeks ago. On roughly flight 200, it was making a very slight funny noise as I landed and I thought a zip tie was simply rubbing on something so I decided to fly my last battery of the day and check it when I got home. One minute into the flight the noise got worse and as I was considering landing, the esc went up in smoke and lots of flames (the glow guys thought it was ironic that my electric heli was burning up ). My post mortem found that the motor was "crunchy" to turn. I had to replace the motor and esc and now it's fine again. I believe the bearings wore out and the motor overloaded the esc and caused all the problems. It also fried one of the cells in one of my 6s batteries.

On a happier note, my A50-12L powered slick has passed 15 hours of flight and is still going strong. I should probably figure out if I'm supposed to be lubing the bearings though so that I don't run into the same problem...
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Old Jul 18, 2011, 08:37 AM
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Florida
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Originally Posted by Sukhoikid View Post
Due to this being my first big electric I need to pick up a meter. But I only ran the xoar for four or so flights and notice it running very hot with it. The apc prop I had on was the same prop I had since maiden and gave me zero issues. Plus it runs cooler than the xoar. I wonderig if maybe I damaged the motor with the xoar and when I flew with the apc this weekend the motor kept getting worst....
A wattmeter is a DEFINITE must. A fishing scale so you can measure thrust is good too but a wattmeter is a must. When motors and ESCs start getting expensive, and the planes, knowing what your exact system is doing is a must. Wattmeters can be had for less than $50, its a worthy investment.
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Old Jul 18, 2011, 08:51 AM
nsg
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Yardley, PA
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Originally Posted by 94'325is View Post
Interesting. My Scorpion 4025-16 just crapped out on me. I was pushing it way too hard, 2300 Watts on a Xoar 19x8 (rated for 2000 Watts max). ...

Anything above 17x8 Xoar for that motor on 8s is just asking for it to be fried. Scorpion tends to rate their motors very optimistically - what they say 15 sec max is exactly that. It's a very nice motor if you keep the current under 65A or so.
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Old Jul 18, 2011, 08:51 AM
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United States, FL, Marianna
Joined Apr 2011
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To run 8s using 2x 4s4000 packs do I need something like this
http://www.rcdude.com/servlet/the-74...Harness/Detail
Or this:
http://www.rcdude.com/servlet/the-18...-Module/Detail

Or should I just wire them up to the esc?
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Old Jul 18, 2011, 09:05 AM
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United States, TX, Benbrook
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Originally Posted by dentalpain View Post
To run 8s using 2x 4s4000 packs do I need something like this
http://www.rcdude.com/servlet/the-74...Harness/Detail
Or this:
http://www.rcdude.com/servlet/the-18...-Module/Detail

Or should I just wire them up to the esc?
Yes use the Harness. You can solder up your own as well which is what I did.
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Old Jul 18, 2011, 09:14 AM
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Florida
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Originally Posted by nsg View Post
Anything above 17x8 Xoar for that motor on 8s is just asking for it to be fried. Scorpion tends to rate their motors very optimistically - what they say 15 sec max is exactly that. It's a very nice motor if you keep the current under 65A or so.
On the 18x8 at 1980ish watts I was at 64 Amps. It still got a little warm at the end of the flight but nothing like the 2300 watts the 19x8 did. I'm going to attempt to rebuild the Scorpion and put it in something else, I've got a Motrofly 4325-280 on the way which should give me the power I'm looking for. I've had other Scorpions and they are great when you don't push them, I like how light they typically are.
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Old Jul 18, 2011, 09:41 AM
nsg
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Yardley, PA
Joined Sep 2006
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Originally Posted by 94'325is View Post
On the 18x8 at 1980ish watts I was at 64 Amps. It still got a little warm at the end of the flight but nothing like the 2300 watts the 19x8 did. I'm going to attempt to rebuild the Scorpion and put it in something else, I've got a Motrofly 4325-280 on the way which should give me the power I'm looking for. I've had other Scorpions and they are great when you don't push them, I like how light they typically are.
Something doesn't add up here. 1980/64 = 30.9V, which means your batteries hold the voltage really well. At that voltage, 18x8 should pull a lot more than 64A. Are you sure you measured your current correctly?
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Old Jul 18, 2011, 09:57 AM
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Florida
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Originally Posted by nsg View Post
Something doesn't add up here. 1980/64 = 30.9V, which means your batteries hold the voltage really well. At that voltage, 18x8 should pull a lot more than 64A. Are you sure you measured your current correctly?
Yeah that was off of the Wattmeter directly and also what the online calcs are saying as well. A few other guys earlier in this thread are reporting the same numbers as well. This was on 8S 30C 4000 mAH batteries too.
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