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Midland Helicopters . HeliProz . ZoomsHobbies

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Gasser Model RC Helicopters > John Crotts taking pictures of Lightning while I am running for my life....
 
 
Red-Rx7
Senior Heliman
Location: Olathe, KS - USA

So today I decide I am going to break in my brand new Vario Benzin Trainer. I spend the afternoon going over everything, validating I have all of the TX programmed correctly; even calling John Crotts (xcellgasman101) asking him a few questions along the way.

Around 7:30 PM I take the Helicopter to a near by empty field (I live in Kansas - no cows were harmed during this attemp); and go through another dry run on everything before the maiden start.

Cyclic movements were working well - Check.
Throttle and Throttle Trim was working well - Check.
Linkages all secured - Check.
TX fail safe's are all set - Check.
Throttle Hold enabled - Check.
etc . etc . etc.

I made a quick "oops" when pre-mixing the Lawn-Boy Ashless 2-cycle oil with the Coleman fuel, putting in 5 oz instead of my intended 4; creating a 32:1 Oil/Fuel mixture. I think this may have saved me in the end.

Anyhow, I get everything primed and setup to go. I prime the bubble, close the choke, give it a quick pull to turn over, set the throttle trim, open the choke and Wham! Starts right up.

I then let go of the head and look behind me to where my TX was laying the ground. In that two second instant that I look behind me, the blade spins and wacks my knee. (Not very much momentum, as it was about an inch away from it anyhow). I fall backwards as the motor spins to full RPM.

I scoot away as quick as possible, and the helicopter remains on its skids but is wide open throttle. The tail blades strike the ground when the main blade hit my knee, causing it to crumble apart and strike the rear tail fin. The tail gear box then rotates 90o and the blades bind with the tail fin.

Meanwhile, the helicopter is just humming along Wide Open Throttle, with no vibrations or ground resonance at all. Frantically, I try everything possible to stop it without physically touching the helicopter. Throttle cut, Throttle Hold, zero stick throttle, reset of trims, etc.

So for 20 minutes the helicopter sat there WOT on its very first crank over. While I waited for a chicken dance and complete melt down, I grabbed my Tac and measured 186 in the window. 1860 RPM head speed, running for 20 minutes. Woot, what a way to break in the motor!

Finally, the motor ran out of gas. It remained completely stable even though the tail was destroyed. After coming to a stop, I grabbed it and took it home for inspection.

I called John Crotts again and told him the bad news without really even looking over the helicopter. Just needed someone to vent to; as I will still shaking a little from the nerves.

Upon inspection, the throttle servo was stuck WOT. Upon powering all of the servos again, all worked fine except the throttle servo. It was non responsive. John suggested that I try to move the servo arm, and it moved after a little push. Trying the electronics again, the throttle servo worked just fine.

Finally, John suggested to wiggle the wires going into the back of the servo. I wiggled them as he advised while moving the throttle back and forth and it died during the wiggle. It looks like the throttle servo has a bad wire or solder connection? I plan on taking it apart tonight and taking some pictures.

So whats with the title of the thread? While my "fun" was occuring, John was trying to take some photos of lightning while it was striking. I guess he got a few as well. Post them John!

The damage:

Tail Blades - ROTORTECH CARBON TAIL BLADES 120MM - $34.95
Tail Blade Holder (103/10) X2 - $17.58
Claw Connector (49/12) - $32.63
Cruciform element (49/8) - $7.90
Total: $93.06 + Shipping

Possibles:
Claw Connector (49/7) - $23.54
Cruciform element (49/8) - $7.90
Stainless steel tube (17/16) - $34.72
Zenoah 230RC Motor - $200.00
Total: $236.16 + Shipping

Here are a few pictures I just quickly snapped. Click on them for a very high-resolution version.

Spark Plug


Engine (Muffler Side)











Tail Box








In looking at the pictures, it seems like the motor might be ok? I figured it would be toast - as I have never thought breaking in an engine on its very first run would be good at wide open throttle, running at 1860 RPM headspeed for 20 minutes.

Any feedback is welcome. I will update this thread with servo pictures when I get it disabled.

Thanks,
Mike
06-23-2008 03:41 AM
 
 
xcellgasman101
Elite Veteran
Location: WOODWARD, OKLA....

Mike your engine looks to be ok,,, Thats some good news,, It doesn't look bad at all.. You got LUCKY my friend,, Congrats,, And the fact that you walked away is amazing!!! Well here are a few pic that I took while we were talking,, XGM/VGM




While no cows were harmed,, BUT,,,, they will never be the same!!!

John Crotts
www.soonerhelicamproductions.com
06-23-2008 04:01 AM
HOMEPAGE  
 
 
windy62
Heliman
Location: USA

WOW!! Glad to hear the damage wasn't more than that.

Quote 
I made a quick "oops" when pre-mixing the Lawn-Boy Ashless 2-cycle oil with the Coleman fuel, putting in 5 oz instead of my intended 4; creating a 32:1 Oil/Fuel mixture. I think this may have saved me in the end.

If your mixing into 1 gallon, doesn't that make it 25:1?

Why didn't the spring on the carb pull the servo closed?

What size blades at 1860 RPM?

windy62
06-23-2008 04:04 AM
 
 
xcellgasman101
Elite Veteran
Location: WOODWARD, OKLA....

Mike do you realize that your motor was at 16,926 rpm,, WOW,,,

Mike and I talked for quit awhile, and went over some very needed safety points,, He got very lucky that his wife was not taking him to the ER,,, First we talked about fail safe, and he did have it set, but if the servo is not getting any signal (from a bad soldier joint) then fail safe is no good,, Second we talked about the choke,, But he was already moving away from the heli, so that was out too,, He was using a Hitec 625 I think and the return spring didn't have enough power to return it to idle,, He is going to change that to something like a JR 4131 or similar,,, Again Mike,, I hate this happened to you on the first flight, but you will be back in the air with little expense, and with all your limbs,,, Keep us informed on how that servo looks,, XGM/VGM

John Crotts
www.soonerhelicamproductions.com
06-23-2008 04:25 AM
HOMEPAGE  
 
 
windy62
Heliman
Location: USA

I may be wrong, but without a signal, there should not have been any power HOLDING it in place. Yes there is power to the servo, but no COMMAND to hold a specific place....

Maybe?

One other thought, I keep seeing that the benzines limit their rotor head speed to 1400 or something. Would an inspection or replacement of the plastic blade grips be a good idea? Course if they held up for 20 minutes at that RPM, they're probably GOOD!!

windy62
06-23-2008 04:37 AM
 
 
xcellgasman101
Elite Veteran
Location: WOODWARD, OKLA....

The return spring is not very strong, and with this servo, it takes some pressure to move it, the Autopsy will tell the story about what happened,,, I'm thinking the signal wire came loose, and touched the power wire, and sent the servo to full throttle., then died,, the return spring, didn't have enought power to return it to idle,, Just my thoughts, for now,, but the servo will tell the story,, XGM/VGM

John Crotts
www.soonerhelicamproductions.com
06-23-2008 04:47 AM
HOMEPAGE  
 
 
xcellgasman101
Elite Veteran
Location: WOODWARD, OKLA....

Quote 
Would an inspection or replacement of the plastic blade grips be a good idea?

That would be a very good thing to do,, I would say if the bolt holes are not out of round, then they are probley ok,, but It might be a safe'er bet to replace them,, as they did get a good stress test!! XGM/VGM

John Crotts
www.soonerhelicamproductions.com
06-23-2008 04:51 AM
HOMEPAGE  
 
 
Red-Rx7
Senior Heliman
Location: Olathe, KS - USA

Thanks for the replies. Those pictures of lightning look pretty sweet John!

In trying to remove the tail, I found it nearly impossible. In fact, I asked myself three times "Was I drinking and glued this sucker in??". Then I took a guess, and unfortunately I was correct: the boom grip melted and ceased the boom and couplers together.

Also the claw connector is bent, for when I rotate it it has a good wobble in it. Also the claw connector on the shaft has been ground down to almost no prongs holding the Cruciform Element on.

I am going to have to do some major surgery here, as it looks like melted plastic with metal dust has been added with the platic. It is really strong!

I think I am going to have to add a few more parts to the repair list.

In regards to the return spring, it does not have enough power to move the servo even when it is off and no power applied to it. I can set the servo arm at 90o and have the carb butterfly 1/2 open and the spring will not pull the servo to a closed position.

I will tear the servo apart tomorrow. I was just trying to get a parts count so I could call Joe and order some new parts to be up and going for next week.

Pictures:



06-23-2008 04:56 AM
 
 
xcellgasman101
Elite Veteran
Location: WOODWARD, OKLA....

 That must have gotton really hot there to melt the boom to the boom mount,,

Quote 
Those pictures of lightning look pretty sweet John!

Thanks Mike, I'm pretty stoked about getting what I got,, XGM/VGM

John Crotts
www.soonerhelicamproductions.com
06-23-2008 05:08 AM
HOMEPAGE  
 
 
Heli 770
Elite Veteran
Location: Lemon Grove, Ca. USA.

While the the heli was doing all of this was the the Helicommand in horizontal or position hold?
06-23-2008 05:09 AM
 
 
Red-Rx7
Senior Heliman
Location: Olathe, KS - USA

I had the Helicommand in an "off" state; or "Red" mode.

I am not sure what I can salvage on the tail boom. I could save a few bucks if I could successfully remove the boom grips; but it is going to be difficult. If I were just to replace it all; it breaks down to the following:

1 x Tail boom holder 20 mm - $22.65 (piece that melted)
1 x Claw connector, shaft 5 mm - $35.31 (piece that drives the tail within the frames)
2 x Ballrace 5 x 13 x 5 mm - $22.06 (two bearings that support the piece above)
1 x Claw connector, shaft 5 mm - $32.63 (tail box claw)
1 x Tail boom 20 x 0.8 x 900 mm, titanium - $29.05 (bare tail boom)
1 x Stainless steel tube 6.0 x 0.3 x 950 mm - $34.72 (torq tube)
2 x Cruciform element - $15.80 (joint connections)
1 x Connecting plug for 6 mm tube - $9.39 (secures claws onto torq tube)
1 x Grubscrew M4 x 4 flat - $3.28 (screws the claws onto torq tube)
2 x Claw connector 6.0 mm - 47.08 (claws that attach to torque tube on each side)
1 x PVC sleeve for aluminium tail boom - $14.60 (inserts in the tail boom to support torq tube)
3 x Ballrace 6 x 13 x 5 mm - $30.84 (bearings for PVC sleeves)
2 x Tail blade holder - 17.58 (tail blade grips)
1 x Tail rotor holder, al. 20 mm - $33.82 (secures the tailbox)

Total $348.81
06-23-2008 05:22 AM
 
 
TVAILLANCOURT
Senior Heliman
Location: Edmonton Alberta Canada

electronic engine kill switch

This is exactly why I have an electronic ignition cut off switch.$40 bucks could have saved you a pile of cash.One flick of a switch from your TX and engine dies.
42percentproductsdotcom
06-23-2008 05:24 AM
 
 
Red-Rx7
Senior Heliman
Location: Olathe, KS - USA

TVAILLANCOURT
Quote 
electronic engine kill switch

This is exactly why I have an electronic ignition cut off switch.$40 bucks could have saved you a pile of cash.One flick of a switch from your TX and engine dies.

I have never heard of this, nor when I speak to anyone about needed parts for the gasser no one ever mentions this either. I have cruised the Gasser section for a little while now and haven't seen any threads either.

Can you link the product that you use?

In hindsight, I think it could have saved some of the parts; but the tail destructed pretty quick. The melting and such for the entire boom would have been saved most likely. Either way, I would be interested to see what you are talking about.

Thanks,
Mike

EDIT: I see the URL you posted in text (not sure why in text); but here is the product?

http://42-percent-products.com/gas-accessories.htm

06-23-2008 05:32 AM
 
 
TVAILLANCOURT
Senior Heliman
Location: Edmonton Alberta Canada

OH by the way replace those main grips and get new blade grip bolts.Those bolts are most likely bent.I had a Benzine throw a blade in flight from over reving on the rotor.I was setting up a GV-1 but had the wrong gear ratio programed and when I hit idle up the head speed shot up and before I could turn idle up off it exploded in mid air.When they say do not exceed the recomended RPM they mean it.

Gasser was a right off and there was not much left after falling 100 feet wide open with no blades or boom.Cut it right in half.

Concider yourself very lucky.
06-23-2008 05:35 AM
 
 
TVAILLANCOURT
Senior Heliman
Location: Edmonton Alberta Canada

Yes that is my post from another thread.It works great.Although some people think it's just something else that can fail.
No probs with it so far.
06-23-2008 05:37 AM
 
 
xcellgasman101
Elite Veteran
Location: WOODWARD, OKLA....

Mike,, Don't forget to ask Joe about the discount,, I think Vario has some kind of discount on parts, to help out,, it might not be that high when you get done, Just a thought,, It does add up quickly on a Vario,, Let me know if there is any thing I can do to help. I have a Vario just setting here if you need any parts to get yours back up and running,, XGM/VGM

John Crotts
www.soonerhelicamproductions.com
06-23-2008 05:46 AM
HOMEPAGE  
 
 
TVAILLANCOURT
Senior Heliman
Location: Edmonton Alberta Canada

z-Kill switch

Here is a pic of mine.It's about 1/2 the size of a GY401

06-23-2008 05:57 AM
 
 
Red-Rx7
Senior Heliman
Location: Olathe, KS - USA

John,

Thanks for all of your help! It is really appreciated.

Here are a few more pictures of the tail. I had to use a bandsaw and cut the grips in half (like how they normally form together to grip the boom). It is amazing how much damage is done.

Look at the pictures. It looks like the boom actually melted! This is suppose to be a Titanium boom! Titanium melts at 3034 °F; so I am not quite sure if it is really Titanium? Or maybe the pictures are misleading?

Pictures (click on them for high-resolution):



























Crazy!

No way I can salvage this boom, torque tube, or any of the inside parts between!
06-23-2008 06:16 AM
 
 
pgkevet
Veteran
Location: surrey UK

Wow, sympathies!

Easy to be wise afterwards but assume an idea to warn everyone on a maiden to go with less than 1/4 first startup?

I don't understand how this happens if the throttle servo was checked as throttle throw, throttle trim and throttle hold? It implies a working servo that died at the point? That suggests binding and it stripped a gear rather than electrical to me..

pgk
06-23-2008 06:21 AM
 
 
xcellgasman101
Elite Veteran
Location: WOODWARD, OKLA....

pgk,, he can kill the servo by moving the servo wire that comes out of the servo,, there is a bad soldier joint in there or a broken wire,, the servo will work if he moves the servo wires around, and it was working before he started the engine, after the engine started, the servo shorted out, went to full throttle, and died,,,



Mike,, Man, that thing got HOT to do that damage,, but at those rpm's that it was turning it doesn't suprise me at all.. Looks like after the tail strike, it got bound up and just ground it's self to nothing,,,, I'm interested in the servo and what you find there,,, XGM/VGM

John Crotts
www.soonerhelicamproductions.com
06-23-2008 06:44 AM
HOMEPAGE  
 
 
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Gasser Model RC Helicopters > John Crotts taking pictures of Lightning while I am running for my life....
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