Safety Lesson - Unplug the Motor!

[DeeEff]

I'll try to make this brief. (sorry, I failed.)

Before performing ANY type of heli work with the battery plugged in, UNPLUG THE MOTOR.

I was introduced to RC helicopters by a friend two months ago, and I am now hooked (see my sig). I'm slightly OCD, mechanically inclined, and love flying my birds. My ultimate goal is to fly 3D, but that's a looong way off -- I can outfly my FP helis with no problem, but just started flipping my mCPX, which is definitely teaching me collective management.

I dumb-thumbed my (previously-owned) T-Rex 450 Sport into the ground a week ago (rebuild is waiting on parts), and just finished my 450 Pro build and am hovering it nicely (but mostly very low to the ground, not wanting to duplicate my Sport crash). Liking Blade helis so far, I picked up a Blade 450 3D BNF yesterday to use as a less expensive trainer than my Pro.

I unboxed it, checked all moving parts and critical non-moving parts for tightness, proper operation, etc. Attached battery, bound it to my DX6i. Double-checked that Throttle Hold was set. Checked for proper swash movement and gyro response. Noticed that the swash was moving down when collective stick was moved up, and vice versa. Thought that was wrong. Went into Reverse menu to fix it. Switched THRO from N to R.

The heli immediately spooled up on my kitchen table (a.k.a. workbench). I grabbed it and held it sideways by the skids away from my body with my left hand while I tried to kill it with the radio on the table in my right hand but flipping throttle hold didn't stop it and flipping throttle hold back didn't stop it and moving the collective up and down just made the blades spin FASTER and what the hell am I going to do, just let the battery run out? Can I unplug the battery with one hand while this thing's spinning at 2,000,000 RPM three feet from my face, let's try it, nope, the connector needs two hands to unplug. Flip all other TX switches one at a time back and forth, nope, some of them make it faster but none of them stop the blades, finally realize that I need to undo the last thing I did so I switch THRO back to N and throttle down and the blades stop and I unplug the battery.

Those were some of the longest 30 seconds I've ever experienced.

After the shakes went away I assessed the damage: two badly nicked rotor blades, and one separated elevator servo pushrod. The blades took a nice chunk out of my toolbox, and I'm guessing that the restrained full thrust basically ripped the ball link off of the end of the pushrod.

Then I assessed the cause: I switched the Throttle reverse setting when I shouldn't have. I should have switched the Pitch reverse setting, except I shouldn't have done that, either! IT WAS FINE. The Blade 450 3D's swash moves up to decrease pitch and down to increase pitch.

Moral of the story?

Before performing ANY type of heli work with the battery plugged in, UNPLUG THE MOTOR.

Thanks for reading this.

-Don

[brent.downey]

Been there... Done that!

Got myself a bunch of stitches down the middle finger of my left hand.

I did the exact same thing on a 450 Clone in the middle of my living room.

Accidentally reversed the throttle on the DX6i and up it went.... my reaction was to swat it out of the air.... believe me. It was a good decision because I was NOT the only person in the room. The 450 went sideways and hit the floor and blood went all over the walls... it was like Charles Manson made a visit.

Seriously,

Unplug the motor.

[JookSing]

...or as suggested in Finless Bob's CCPM part 1 video, instead of plugging in the big lipo, use a receiver pack. All you have to do is plug it into the binding plug slot of the receiver.

[JookSing]

Deleted...double post.

[Gadflyii]

Check your shafts, willing to bet u bent them

Glad u are ok, and not hurt. If something like this happens again let the heli destroy itself, and get away. DO NOT try and grab it.!!!!!

Sent from my PG86100 using Tapatalk

[DeeEff]

Originally Posted by Gadflyii

Check your shafts, willing to bet u bent them

I double-checked everything this morning, all looked okay. I was hoping that as the actual blade strike (on my toolbox) was very light that I avoided bent spindles, but checked those out as well.

Just finished test flights #1 and #2, everything seems fine -- no shakes or wobbles other than a little tail wag that I'll fix with gyro settings. I installed new blades after balancing them (I don't know if I'll sand the old ones down and try them... probably not), and spent flight #2 adjusting tracking.

Nice heli!

Originally Posted by Gadflyii

Glad u are ok, and not hurt. If something like this happens again let the heli destroy itself, and get away. DO NOT try and grab it.!!!!!

I'm with you there, mostly. I grabbed it as the blades were just starting to spin up, and the rest is history. If I had let the heli destroy itself (via the overhead kitchen light, ceiling, refrigerator, china cabinet, walls, etc.), I doubt I would have been able to get away before it bounced off of me a few times.

-Don

[4n6days]

A little trick I use when working on some aspect of the heli that requires the motor to be plugged in, like setting up an ESC, is to swap two motor wires so that it sipns backwards and just spins the gear and autorotation bearing.... but not the blades. This doesn't work on a heli with a non-driven tail or one without an autororation bearing... If you do this, make sure to do a controlled test before getting your hands near the blades.

[DeeEff]

Originally Posted by JookSing

...or as suggested in Finless Bob's CCPM part 1 video, instead of plugging in the big lipo, use a receiver pack. All you have to do is plug it into the binding plug slot of the receiver.

I'm going to go this route -- any reason why I should pay ~$70 for the Spektrum pack (SPMB4500NM) instead of buying the $20 Losi pack with charger?

-Don

[donmei]

Dee Eff,

I did the same thing with a HBFP. It flew across my basement and scared the crap out of me. The HBFP can't do anywhere near the damage a B450 could do.

You got really lucky. But you know that.

Thanks for sharing.

Don

p.s. You could have turned off the transmitter and it would have shut down the motor. Thats part of the DSM failsafe.

[DeeEff]

Originally Posted by donmei

p.s. You could have turned off the transmitter and it would have shut down the motor. Thats part of the DSM failsafe.

Howdy, Don -

D'oh! I didn't think of that!

Just tested it out (sans blades, of course). It works!

Thanks,
-Don

[donmei]

Its no surprise that I thought of something you didn't.
I have the luxury of sitting in a comfy chair thinking of things, while you were reacting to a terrifying incident, trying to keep a 3/4 hp buzzsaw awayfrom your face.


In the real aviation word there is a saying that goes something like this:
My superior judgement precludes me from having to demonstrate my superior skills.

Its good words to live by. Since my HBFP incident, I don't trust any helicopter. When I plug the battery in, I assume the motor is going to jump on at full power. Thats just me. I'm paranoid.

[gso125]

Been very lucky myself one late night trying to set end points and autorotation stuff with a castle esc in a trex pro I had it on fast start and reversed the throtle by accident busted up a bunch of stuff no injuries but wasn't so lucky 20 + years ago adjusting a prop on a gas plane split my index finger the whole length bunch of stitches. I'm looking at the scar mostly gone now very lucky. Moral for me is to slow down and pay better attention before I mess with stuff.

[Inverse]

+1 on getting an Rx pack or cheap BEC when setting up.

[Sharkey_t]

when i was checking setup on my b450 the first thing i did was remove the blades. i wanted to spin the motor up and check it all out, and i wanted to learn how the swash moves in relation to collective and cyclic inputs, so it made more sense instead of unplugging the motor.

[JookSing]

Originally Posted by DeeEff

I'm going to go this route -- any reason why I should pay ~$70 for the Spektrum pack (SPMB4500NM) instead of buying the $20 Losi pack with charger?

-Don

Well, I don't think you need one as powerful as the model number you mentioned above. The reason you want to go with the Spektrum pack is because the plug on the battery is made to fit into a Spektrum receiver which is what the Blade 450 comes with. You can then charge the battery with the DX7's charger.

If you're not in a hurry, you can find some great deals in the "for sale" section in the variuous RC forums.
If I remember correctly, a seller at RCGroups sold me 2 of these receiver packs that came with the DX7's for $22.00 shipped with a couple of switch harness'.

Or you can try Ebay if you can't wait:
http://cgi.ebay.com/SPEKTRUM-B1500NM...item3f0a699a24

http://cgi.ebay.com/SPEKTRUM-B1500NM...item5ae0ce2af2

They work perfectly for me.