65" Vyper Discussion Thread

[SnowDog]

Ok, had to start a Big Vyper thread...just finished mine recently (I know, this is an "older" 3DHS airframe, but I just got mine recently at the last garage sale)

This pic has big brother and little brother on it.

 

[Joe's Dad]

picture Site

 

[SnowDog]

I was flying my 65" Vyper on Monday. About halfway through the third flight the motor started sounding different, but it seemed to be flying okay, so I kept going. As I was doing a last hammerhead before landing, I flipped over at the top and as the nose pointed down, I noticed white smoke trailing from the plane! I thought "cool, smoke on an electric plane"...then I thought "wait a minute, I don't have a smoke system on there!", then I realized "my plane is smoking! electric fire onboard...crud...)($#$* so I cut the throttle and brought it down, landing gently on the edge of the field in the tall grass...ran out to the plane, pulled the cockpit, unplugged the battery, ran it back to the pits, started pulling off the spinner, prop (which did not break!), and cowl..everything was super hot to the touch, got it apart, noticed that the motor can had come apart somehow or slid forward, you could see the magnets from the rear edge of the can...couldn't touch the motor. I put a wet paper towel on the can to help cool it down and it started sizzling immediately...finally got it cooled down. So other than the motor, there is no other damage to the plane. The prop even survived. I feel really lucky that it turned out this way. Not sure what happened to the motor...I bought it used from a reliable source, and I don't think I was over taxing the motor. It was pretty hot today, not sure if that had anything to do with it.

Anyway, I attached a few photos for your enjoyment.

[FONT=arial, helvetica, sans-serif]Still haven't had time to pull the motor off the plane, but it definitely does not move easily. Probably gonna have to replace it. Time for a Motrolfly!

[/FONT]

 

[3dNater]

Mike your magnets have broken loose from the can and it looks like they are rubbing on the base of the motor. This is likely the cause of your excessive heat. I had a similar issue with a hacker motor. I tried re-gluing the magnets with limited success and ultimately burned up the motor windings. It looks like you are in the market for a new motor.

I'm not sure what causes the glue to break loose from the magnets but the failure I had on my hacker looked similar to what you have there.

 

[gyro]

Generally, for all the magnets to break loose like that, there has to be sufficient heat to break down the epoxy holding the magnets, which by Mike's description, occurred here.
So that brings the next question: what caused the heat? A couple possibilities come to mind here: too big or too much pitch on the prop, inadequate cooling air to the motor, old/worn bearings causing friction. I'm not sure if any of these apply in Mike's case, but that's where I'd start.

 

[SnowDog]

Well, I don't think I overpropped...here is the prop data chart for the motor:
http://www.scorpionsystem.com/files/i1,417_data_chart.htm
I am using a ProTek 18x10 electric (wood) prop with a 6S5000 battery and a 120A ZTW ESC.
I believe everything is within good operating parameters.
I suppose heat is the culprit, although this was a used motor so I can't vouch for the state of the bearings.
I had around ten flights on the motor when this happened. I have not modified the cowl to provide any cooling beyond what the stock setup offers.
I know I'm definitely in the market for a new motor, and the Motrolfly 4325-380 will be my motor of choice:

DM4325-380

3D Planes up to 11 lbs. Sport Planes up to 16 lbs.

6s Lipo 2200 W

Best 6s for 70" 3D 19x10 on 6s

More Info Coming Soon

18x8 APC, 21.7V, 6600 rpm, 59.36 amps, 13.9 lbs. thrust
18x10 APC, 22.0V, 6400 rpm, 71.0 amps, 16.25 lbs. thrust
19x10 APC, 22.1V, 6125 rpm, 83.77 amps, 17.5 lbs. thrust

It is an expensive motor, but this airframe is worth it!

 

[gyro]

Mike, I ran the 4320 in my 65" Vyper, custom wound down to 300 for 8s, and it worked PERFECT with an 18x10 protek. Speeds upward of 70mph I believe. The 4325 might give you too much forward CG.

 

[bruceman]

Mike,
Glad you made it back on the ground intact!!!
I had a scorpion in runner in my RC truck, and the housing developed a hairline crack which made the motor run hot due to the magnets not being cocentric with the stator. I sent it back to Espirit and even though I bought the truck used with that motor in it, they got me a replacement, shipping only was charged. Try calling Espirit, these guy's are top notch, maybe they can get you a warranty replcement. Never hurts to try, that's not a cheap motor, and Scopion is a good motor.
Bruceman.

 

[gyro]

Lucien (Innov8tive) also a member here... maybe he'd be able to help?

 

[SnowDog]

Mike, I ran the 4320 in my 65" Vyper, custom wound down to 300 for 8s, and it worked PERFECT with an 18x10 protek. Speeds upward of 70mph I believe. The 4325 might give you too much forward CG.

Gary, thanks for pointing that out...I wasn't looking at the weight, I was looking at the price...for only $10 difference, I can get the more powerful motor and have one good enough for an electruc 71" Slick or 72" Extra someday...but the weight difference is quite large...although there seems to be plenty of room to move things around in the battery tray.