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Century Helicopter . MTA Hobbies . Model Rectifier Corp

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e-Ark X-400 - MX400 > Stripped main gear in flight
 
 
jrohland
Heliman
Location: Arlington, Virginia, US

Since I switched to an AON 3000 and 4 cell batteries, I dropped my pinion to a 10 tooth (9 tooth on the way). One problem I had was that I could not push the motor in far enough to fully engage the pinion to the main gear. (I have since ground out the motor mount adjustment slot on the motor mounting plate to allow more movement of the motor.)

While flying at the park yesterday, I did several high-speed (full left stick) climbs. The last time I did that, I heard a bad noise and the heli started dropping. I controlled the descent the best I could. Once on the ground, I could see the main gear was chewed up and spit all over the heli.

Is it possible an X400 is not tough enough to handle 4 cell power? So far, I have put the blame on misadjustments and screwups on my part. However, I am starting to wonder.

jrohland
05-08-2006 Over year old.
 
 
kjiuo
Heliman
Location: detroit

You made it sounds like a gear meshing problem. The ideal space between gears is about the thickness of a piece of paper.
05-08-2006 Over year old.
 
 
NTM
Senior Heliman
Location: Lloydminster, Alberta, Canada

I'm running a 450th on 4 cells with 325mm blades.

The only way I could get it to stop killing main gears under hard collective reversals was to run the gear mesh very tight, too tight in fact.

I think microheli makes a main gear, for the mx400, that would do the trick.
05-09-2006 Over year old.
 
 
NTM
Senior Heliman
Location: Lloydminster, Alberta, Canada

Also I found the carbon top frame deflected laterally enough to loosen the pinion/main mesh enough to allow it to strip.
Changed back to the aluminum top frame and all is well.
05-09-2006 Over year old.
 
 
Dennisu
Veteran
Location: Surrey, B.C. Canada

jrohland

Did you also check the modulus of the pinion to make sure that it's 0.5mm to match the teeth on the main gear?
05-09-2006 Over year old.
 
 
ncpiperpilot
Heliman
Location: NC

I started having the problem stripping main gears on my MX400. It's now happened 3 times. I am using the MX400 to learn basic aerobatics. FFF and hovering, no problem, but on three flights, I have stripped the gear pulling out of a loop. I am setting mesh up correctly with a very small amount of free play - tighter and it "binds". Running 3S. I know its probably bad collective management, but wondered how others solved this.

A little history is important:

Original set-up: Helimax 2580kv motor and HeliMax ESC. 285mm blades. Never stripped a gear. (BTW...the spoolup/speed change is quite quick on this ESC as its not programmable)

#2 set-up: Align 3550kv motor/11T and Align 35G ESC. No problem until I switched to Align 315 Carbon blades...1 flight is all it took to strip the main coming out of a loop (yes I know those blades are junk). I was turning about 2600 with this set-up (90-85-80-85-90 on Idle 1)

#3 set-up (current): HDX450 3200kv(XMSeller)/11T and CC Phx-35. I lengthened boom to use Align 325mm Pro Woodies. Headspeed about 2380 (100-95-90-95-100 on Idle 1)not running Gov mode. This motor is nice as the kv matches up well with the 138T main, but its not a big powerhouse. Experience:

- 2nd stripped maingear coming out of 1st attempted loop.

Set up CC35 to a slower ramp speed - (setting 3 of 10) I think.

- 3rd stripped maingear coming out of 1st attempted loop.

I think its the combination of the greater momentum of the bigger blades and the new power system.

So...I am going to switch over to Gov mode and get more gears, but how many others are stripping mains in aerobatics? Seriously I didn't think I was being that aggressive on collective.

Alternatively, I see microheli has a machined main gear...anyone have experience with that...did it solve stripping problems????
09-11-2007 Over year old.
 
 
HELIVAGUY
Senior Heliman
Location: Monmouth County,NJ USA

have you tried using the align gears? (with correct pinion as the align gear has more teeth i beleive).
i know helimax/ark had problems with the main gears being out of round or oblong.

Have a Heliva Day!
09-13-2007 Over year old.
 
 
Dennisu
Veteran
Location: Surrey, B.C. Canada

HELIVAGUY

I believe that was Align that had the problem with out of round main gears.
09-13-2007 Over year old.
 
 
Dennisu
Veteran
Location: Surrey, B.C. Canada

ncpiperpilot

The main gear on an (M)X-400 should not strip if you have the right modulus pinion, the pinion is aligned properly and the ESC is not allowed to spool up the rotors too fast from a dead stop. Mind you if you have a 10 cell battery on a 400 machine you can do wonders to a main gear no matter what it is made of...........
09-13-2007 Over year old.
 
 
ncpiperpilot
Heliman
Location: NC

Helivaguy - the Align gear is 150T and won't fit the MX400 chassis without a lot of chopping.

Dennisu - Thanks, good input. Unfortunately I don't think thats the case here.

Amyone have experience with the microheli machined gear? Is it tough or just more round?
09-13-2007 Over year old.
 
 
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e-Ark X-400 - MX400 > Stripped main gear in flight
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