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Kraken is grounded with recomended equipment.

Maingear

Flugzeug Liebhaber
#1
I had three fried ESCs and a month's worth of no flight time out of my Kraken. I have less than 30 min total time flying my kraken, the last flight I had to crash land in a soybean field due to a #2 ESC failure on final. The bird is incredible to fly, but something is not right.

I used the components recommended, communicated to factory support, and my retailer.

The retailer has been very patient, told me the recommended prop is wrong for the motor.

Here are the related links to the original problem:
http://forum.flitetest.com/showthread.php?10878-Kraken-Incident-Report

http://forum.flitetest.com/showthread.php?10547-Suppo-motor-and-esc-help!-!

Comments / Suggestions?

What is working in your Kraken? Please post pics.
 
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joshuabardwell

Senior Member
Mentor
#3
The plane's all-up weight without battery is nominally 27 oz. Add another 10-20 oz for batteries, depending on how big you go with, for a total AUW of 37-47 oz. With a 9x5 prop on 3S, the recommended motor produces 41 oz of thrust at 21 amps. With two motors, you should have a TWR of about 2:1, which is superb. Even if you add a bunch of FPV gear, you should be able to keep the TWR above 1.5:1, which is more than adequate. I'd say, keep the electronics the same and try a 9x5 prop.
 

Maingear

Flugzeug Liebhaber
#4
Update Recomended Equipment?

keep the electronics the same and try a 9x5 prop.
That is what the company I bought the motors and esc suggested 9x4.7. I've already bought 7x4.5's thinking about running 85% throttle hoping not to load up the ESCs. We do have a nicely manicured, long & wide runway at the flying club which has come in handy before.

BWT - The first ESC was fried with a 2S 20C 5amp/hr battery. :confused:

I don't mind being the guinea pig, I just don't want anyone else to have this experience.

Justin
 
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Craftydan

Hostage Taker of Quads
Moderator
Mentor
#5
Justin,

I agree, the spec is overpropped . . .

. . . but that is odd. That motor swinging a 10x6 on a 2S pack should be drawing around 14A, not 22A the motor is rated at or 30A the esc is rated at. On a 3S pack the motor totally should have smoked after 30s or so of flight . . . but the ESC?!? you should have never drawn 30A in EACH ESC. Not saying you didn't see what you saw, just saying it doesn't add up . . . my bet, defective ESC smoked on day 1, overpropped motor smoked on day 2.

Looking at the screencaps on the build page . . . those aren't supo motors. they look like the Emax motors used in beef packages, and 10x6 would be a good size for a few of those. Makes me wonder if they chose to spec a different motor/ESC then forgot to change the prop.

BTW, just from mere size, I'm inclined to recommend a 3S-4S power system, since the added power you need for that big of a wing could really take advantage of the lower current demand the higher voltage provides . . . just realize as voltage goes up, prop size goes down.
 

earthsciteach

Moderator
Moderator
#6
I know for a fact that the 2217-7 will swing a 10x4.7 prop just fine. That is what Josh B flies in his Storch. I don't know what esc he is using, though. But, a 30 amp should definitely cover it.

Correct me if I'm wrong here, Dan (and you know me well enough to know that is an outside possibility :p), but don't motors try to draw a certain amount of power? And, power being equal to Voltage x current, if the voltage drops, the motor will pull more current to try to hit that power. Therefore, the 2s battery may be the culprit.

Just a theory.
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#7
Pat,

from his linked log, his first set of flights were on a 2S pack, and no, that should have been fine all the way around :( biggest thing I thought was weird (and why I guess the ESC was bad) -- 10x6 shoud be a cakewalk for that powersystem on 2s.

On the last logged flight he tried a 3S pack, and from the data in the link Joshua posted, WOT is too much for that motor w/ a 10x6 on 3S. would not surprise me Josh is managing his throttle on the Storch, and keeping everything cooled, but an prolonged burst would not fair well . . . according to those numbers.


BTW, not quite . . . motors try to run at a certian RPM at a given voltage, and will do so assuming they don't bog down under load. the more they bog down, the more current they draw (with declining efficency) until the insulation melts from overheating. Ah, the smell of insulation smoke :p

Either way, the lower the voltage, the lower the RPM, the easier it is to turn that prop.
 

Maingear

Flugzeug Liebhaber
#9
For the record, I installed 10x4.5 apc slow fly push and tractor not 10x6....

AR610 receiver with throttle and flap channels controlling ESCs. #1 ESC servo red wire was left in to provide power to RX, #2 was removed. I had 4 guys at prop busters inspect the setup before each flight and supervised me remove and install an ESC in the pit area. I even hooked in an eleven to ensure the signals were not sperattic to the ESCs. I have been flying that RX in a FT SS while I have been waiting on replacements.

We had a club meeting tonight and I brought the radio there. They checked it out and came up with nothing. The diff thrust worked great!(when the ESC was working).

If you read the links above... I kept blowing the #2 side, then left it off and ground ran the #1, it failed. Check out the details...

Does this site support the DX6 file I set up for the Kraken mix? I could post it.

I can't wait for my parts to come in so I can fly it again! (with a smaller prop)
 
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Maingear

Flugzeug Liebhaber
#11
BTW, you could get away with a y connector easy. I flew it both ways, bank and yank, coordinated, and uncoordinated. It turns very tight with diff thrust.
 

Maingear

Flugzeug Liebhaber
#12
Maybe Suppo has derated their motors to factor in abuse? No idea.

Motors were parallel with 10 gauge wire and 3.5mm connectors. Traxx batt connector(I know lame)
 

Maingear

Flugzeug Liebhaber
#14
Finished my second kraken. Used 9x4.7SF props and recommended suppo components. Maden flight was 15min and had just bellow 50% battery left on the 6400mah 3c 20c batt. Climbed and cruised in 5 mph wind just fine. Spent most of my time just below half throttle.

Very happy with this prop and power plant, the kraken is a blast to fly!

Justin
 
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quickpix

Junior Member
#15
Kraken CG?

I tried to fly my Kraken the other day and it went straight up and did a nose in ground loop.
I figured the CG was where the two holes are but I guess not?
Any suggestions please?
 

Maingear

Flugzeug Liebhaber
#16
The cg is near the rear pod skewer holes. I made a point to mark them so I could find later. You can lay your plans over the bottom wing before the pods are installed, then mark the cg.

I lost my 6400mah battery today. It dropped it like a payload. :( funny thing was it glided back to the runway and crashed in the dead center of the runway!

Will be starting on the third kraken tonight. Plan on making a battery compartment and removable wing.
 
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