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Futaba-RC . A Main Hobbies . Boca Bearings

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e-Thunder Tiger Raptor E Series > E325 Explodes in Mid Air
 
 
Gam
Senior Heliman
Location: Australia

All I could say is 'wow', that was impressive!

Spun up this arvo, (after a session this morning of 4 packs and no problems), and as I got about 2 feet of the ground I flicked the switch to STUNT 1 and the chopper disintergrated. Looked really impressive - wish I had some video of it occuring!



Background: I've had heli since Christmas. I'd had six crashes (five dumb thumbs and 1 servo problem after a dumb thumb crash fix), then no crashes for about five months. I've had the scorpion -6 motor (4400kv) lying around since April, so finally decided to put it in last Sunday. Took her for a fly, and she stripped the gears! Some minor rebuilding, much tighter gear mesh than I'm use too, and up again. Now this.

Anyay, from the picture you can see that the heli basically broke in two between the motor and the main gears. My best guess as to the casue is that the main frame has been weakened over time (and crashes), and that the extra grunt and torque of the 4400kv -6 has had it's toll on it. I didn't check the main frame for cracks after the last crash, however it was such a low speed (almost drop out of a 2 or 3 foot hover) with very little damage (tail fin and a very slight nick in one main blade) that I wasn't too concerned. (I did replace the main shaft, and checked all other spinning parts by removing and checking them).

Anyway - just a heads up that the main frame can be weakened over time (and crashes), and have a really good look there for signs of wear and tear.

Happy Hovering!

I've spent the last 3 1/2 hours rebuilding, and I'm almost done! Hope to be back in the air tomorrow
09-13-2008 02:11 PM
 
 
dave75d
Veteran
Location: Jacksonville, FL

ouch! at least youve got a positive attituide about the crash. build, fly, crash, repeat.

ten grand in helis and all i can do is hover
09-13-2008 05:27 PM
 
 
matnikon
Senior Heliman
Location: Kuala Lumpur-Malaysia

What pinion size is used for this -6 motor?
09-14-2008 02:06 AM
HOMEPAGE  
 
 
AllThumbs
Senior Heliman
Location: New Zealand

Nice Job Gam..
I backed my MT in this morning.. tail first, Back flips just a little too low
But other than boom, blades, main shaft & a tail servo case it looks ok.. I have the Scorpion -8 Motor.. Got to love the power...
Can't say that the E550 was to happy about being flown after seeing the MiniT gettin it.. but it survived.. this time

09-14-2008 02:41 AM
 
 
Gam
Senior Heliman
Location: Australia

11T Pinion - suppose to give 3220 RPM but I haven't tacho it. I wanted a 10T (to give around 2900 RPM) but I couldn't get one easily enough so went with the 11T.

Finished putting it together this arvo, but when I spun it up it looks like the Head Block might be bent as well, as it has a visible wobble at the top of head, even though it has new main shaft, spindle and flybar, gears and bearing - in fact most things!

That will take a couple of days for postage - so I'll have to wait till Wednesday! After all the parts I've had to replace (and had on hand)it sucks to be one short!
09-14-2008 08:19 AM
 
 
beidle99
Senior Heliman
Location: Woodbury, NJ

The 6 turn scorpion has to much power for the TT main shaft. A friend of mine broke the main shaft in flight with the 6 turn. The 8 turn is plenty power.

Who raised the ground since I took off?
09-14-2008 02:55 PM
 
 
Carbon Copter
Veteran
Location: USA

Wow does that main shaft look pretty bent I have never crashed my MiniT, but in all my 450 heli crashes, I have never bent a shaft so badly. lol

~00~ Stop fogging up my glasses
09-14-2008 03:35 PM
 
 
psych-lick
Veteran
Location: Austin, TX - USA

What looks so odd to me is the fact the main shaft is so bent and the feathering shaft, flybar and blades look unharmed.. How did that happen??

-Jeff T.
09-14-2008 03:42 PM
 
 
Gam
Senior Heliman
Location: Australia

Psych-lick, Feathering shaft was pretty bent, flybar was wrapped around itself (I straightened it to fit it back in the box). Main blades were totally unharmed (just as well - brand new set of Curtis Youngbloods.....five flights old)

The head just wrapped around itself inflight. As previously stated - not sure if the front of the heli came off becuase the head let go - or if the front comming off made the head let go. The main gears were relatively unharmed, just a couple of teeth scraped a little - which is what led me to believe that the front came away 1st as the motor gear was then free from the main gear when the head stopped.

Beidle99 - I'm thinking the same. -6 Motor too much power for this frame and setup. I'm interested if anyone else has flown the Mini - Titan sucessfully with the -6 motor?? I like the extra power - however the hassle has definetly not ben worth it. I'm rebuilding back with the standard motor until I can work that bit out.
09-14-2008 11:35 PM
 
 
TMoore
rrProfessor
Location: Cookeville, TN

I have two of the 2221-6 motors in two MT's and the motor has to be geared correctly. An 11 tooth pinion is just right. I've flown it with the 13 tooth pinion and while it is a hoot to fly, the 11 tooth pinion is better for the machine.

Something else most likely happened to the machine to cause it to come apart.

TM

Buying tools is half of the equation, knowing how to use them is the other. - T Moore
09-15-2008 01:48 AM
HOMEPAGE  
 
 
msinawsk
Heliman
Location: PA

the same thing happened to me a few weeks ago. exactly the same story. think there is a problem here?
09-15-2008 02:21 AM
 
 
Gam
Senior Heliman
Location: Australia

Any ideas on route cause then TMoore??
09-15-2008 02:23 AM
 
 
TMoore
rrProfessor
Location: Cookeville, TN

I have no clue. It's hard to say without being there. Could be a build error, a catastrophic failure or something else that is unknown at this point.

TM

Buying tools is half of the equation, knowing how to use them is the other. - T Moore
09-16-2008 04:06 AM
HOMEPAGE  
 
 
msinawsk
Heliman
Location: PA

was just wierd how it happened. decided to install a metal upper bearing housing this time... going to check it out and see how she acts not.
09-16-2008 04:17 AM
 
 
paintball_kidz
Veteran
Location: Surrey, BC Canada

I think that motor is too powerful for a plastic heli

I will build your heli for free.
09-19-2008 04:24 AM
 
 
Gam
Senior Heliman
Location: Australia

I agree that it seems to powerful for the plastic frame. I have been through the entire Heli and there is no other explanation that I can find
09-19-2008 07:14 AM
 
 
TMoore
rrProfessor
Location: Cookeville, TN

The motor isn't too powerful for the heli. I've got that same motor in two MT's and it works fine. I'm running full power to both. One has the Kasama head and the other the TT metal head. Both machines are smooth and powerful with 11 tooth pinions. I ran the 13 tooth pinion before and the HS is a little high for me.

TM

Buying tools is half of the equation, knowing how to use them is the other. - T Moore
09-19-2008 01:44 PM
HOMEPAGE  
 
 
Gam
Senior Heliman
Location: Australia

I guess I'm back to a cracked frame then! Will try it again.
09-20-2008 03:26 AM
 
 
Leavin
Heliman
Location: Australia

GAM, I have had the same problem with my MT, very dissapointing to say the least..
I have got the Green motor on 100-90-100 throttle in st2
but I dont get the exploding heli part when I run it at the 70-90-70 in idleup..
With mine it didnt bust the main frame.. but did stuff the new metal head I had just put on... Just to see if the problem was related to the plastic parts I had left on mine. getting the heli in high head speed and doing full power climbouts is impressive.. but when coming down from the altitude BOOM.. grrrr, thud of the heli.

I am unsure but am wondering if it is a issue with the ball links.

this is the thrid time this has happened to this heli in several configurations..

Interested if you guys find a solution to the issue.

cheers
Gav.
09-30-2008 03:11 AM
 
 
helicraze
Key Veteran
Location: Victoria - Australia

I had my SE explode in mid air, this was when it was first released and parts were hard to find. It cost me about $300 to fix!
09-30-2008 11:53 PM
 
 
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e-Thunder Tiger Raptor E Series > E325 Explodes in Mid Air
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