first flight of my L600, not so good

[th3tick]

Had my maiden of my new L600 flybarless today. Got it up in the air for about 1.5m, then set it down, tweaked my expos (forgot to give it any), and took off again. About a minute later, uncontrollable piro, and i set it down in the grass...

Well, "set it down" is probably a bit kind.

2500 headspeed on a L600 is incredible, BTW. I'd tune that down a bit, but I seem to have more pressing concerns.

Initial inventory of damage:

left and right frames
upper and lower main shaft bearings
main shaft
frame screw set
skid supports
mod 0.7 main gear
anti-rotation bracket
one main servo to swash link set
swashplate and balls
swash driver arms and links
tail boom
tail belt
tail shaft
tail control arm (the one that connects to the long shaft, and the ball on the slider)
main tail fin
brass sleeve and the yoke it screws into
tail control rod and ends

who said that about using nylon screws on the skid holders? Yeah, I deferred that until later. Later's here, and he wants to be paid...

Initial idea is that the pitch slider on the tail came unscrewed. Hard to be sure whether that is post-crash or pre however, but it's almost apart. Tail drive belt was chopped, and remains wrapped around stuff under the main shaft as we.

Ideas?
John

[OICU812]

Well that blows chunks....

Sorry to hear of this...

But I have to say it is kinda well almost impossible for the slider to unscrew itself, I have never seen that happen and the bolt as well that holds the slider arm is tight by nature, i have always wicked in a small dab of ca but have firends how never had and never seen a thread out issue either.... SO I need to ask with of course the risk of it being taken the wrong way...

Are you 100% certain of the following items...

Tail Rotor Hub setscrew was tight and blue loctited?
Bolts holding the tail rotor grips both tight and loctited?
Ends on pushrod are or were epoxied JB welded in firmly and set?
No chance of any plug coming out of the tail rotor channel on the Vtabi portion rx?
Does the tr servo function now?

Uncontrollable piro can only come from the obvious of something pyhsically coming off or unplugged, or the servo itself failing completely. If there was no vibration evident in the heli and nothing was buzzing about then the unscrew part is more then unlikely, and more directed to unplugged, or unhooked of nature....

Anyhow sorry to hear of this, just trying to offer ideas for post crash learnings.

[th3tick]

SO I need to ask with of course the risk of it being taken the wrong way...

Are you 100% certain of the following items...

Tail Rotor Hub setscrew was tight and blue loctited?
Bolts holding the tail rotor grips both tight and loctited?
Ends on pushrod are or were epoxied JB welded in firmly and set?
No chance of any plug coming out of the tail rotor channel on the Vtabi portion rx?
Does the tr servo function now?

No chance of taking this the wrong way. I know it crashed due to something wrong on my build. No chance of much else!

The tail rotor is entirely intact. The only bits out of order are that the slider is out of place, the crank is missing one arm (the one to the slider), one end is gone, leaving an epoxy-smoooth set of threads, and the severed belt.

Given how neatly the tail is chopped off, I think the belt went the same way. Of your list, the pushrod end is the one that's left, and it has tons of epoxy on it, although very cleanly separated from the rod, whereever that went...

The important bits to me were the pack and electronics all intact and undamaged. I just need to decide to re-kit or parts it. I just sent my list off to Esprit to get their advice...

The head is also in great shape - nice and straight, and no notchiness to the bearings. too bad the shaft's in two bits!

John

[LITHIUMSTATIC]

I feel your pain and have been there. At least your Lipo is ok and electronics. :hug:

[BruceW]

Wow, that is bad news John. Very sorry to hear about it.

Based on the laundry list so far it seems like a re-kit is almost the way to go. You are much calmer describing these events than I would be.

Bruce

[Klinger]

Man that suxs, looks horrendous. As stated at least that pack survived, i'd agree a re-kit looks the best and keep what's in one peice for spares, no ideas to help as to the cause!

[Panda]

Ouch, that hurts! Really sorry for you, my maidenflight of my brandnew L500 3D will have to wait a bit, really ****ty weather during the easter weekend here in Vienna!

Good luck for your re-built,

Peter

[Flybar-less]

John that stinks.
The only time I lost the tail on a Logo was when the belt "slipped" off the tail driven pulley. 3 - 3x8mm idler bearings fixed that. I noticed Botos runs 4 wide on His.

[Eyon]

ouch, nasty crash! feelin bad for you buddy. is it worth just getting a new kit?

[Funflyer]

Whoa man, I don't yet own a Logo and I can already feel your pain. Just curious but did you get to the throttle hold button before impact? I'm trying to get an idea about how tough a Logo is.

[Mercuriell]

Mucho condolences man :( - pushrod seems a bit sus to me - much more likely for the thread to come out of that than the silder to unscrew - I've had epoxied threads pulling out of CF and I think I remember Shawn's tip on putting dental floss down to improve thread grip,

[LITHIUMSTATIC]

pushrod seems a bit sus to me - I've had epoxied threads pulling out of CF and I think I remember Shawn's tip on putting dental floss down to improve thread grip,

I'm thinking of buying a rod that passes all the way through the CF rod and threading the ends.... Their is no way it will give any problems of coming undone then.

[flymustangs]

That's what I did on my TREX 450 so I could get rid of the guide. I couldn't get a straight shot between the servo and the tail using the guide. Works great on the TREX.

Ken

[OICU812]

I'm thinking of buying a rod that passes all the way through the CF rod and threading the ends.... Their is no way it will give any problems of coming undone then.

I tried finding one that long Jeremy, I could not locate one that long, if you find one let me know....

I have my stock rods in place just some dental floss to re enforce the hold as mentioned and I also use JB weld myself. Epoxy works as well no issues..On top of all this I usually also heatshrink over the ball link and the rod as a last course of insurance...:)

[th3tick]

Well, I hit the throttle hold way too late I'm sure, not that it mattered. I think there's one dinged tooth on the gear, which is too much, mind you.

It was headed for "things I didn't want to hit", and was in normal, so just slammed the throttle to 0 and set it down. I tried holding it a bit, but full control of a piro isn't in my skillset yet.

I did some amusing calculations of the tip speed on the rotors at impact. I think it came out around 414MPH, which explains why it did a good job mowing just a bit of grass.

Good thought, Jeremy. That may be top of my list when I get to that point. Solid rod, threaded, with the CF as stiffener. Now, where to find a rod that matches...

I'm going through it all, and that does indeed seem the likely cause. The epoxy needs something to grip on, and the smooth epoxy on the threaded rod that remains speaks volumes.

Thanks, all for your support and help.

John

[th3tick]

Dismantling is now complete. I had the rotor strike the tail, so the damage is awesome about three inches from the tail, but most notably, he last four inches or so of the CF tube is completely gone. I went over the area again, but no sign of it.

Totally destroyed, but that doesn't explain its coming apart from the threaded rod completely. I think that's got to be it - prior to the boom strike, it had already given way. Then the smack of the boom strike flung it far.

Time to go hit up the music wire section at a few hobby stores, and look for a die...

John

[LITHIUMSTATIC]

Time to go hit up the music wire section at a few hobby stores, and look for a die...

John

That is exactly what I was thinking.;) If you have a piano repair shop nearby that would also be a good place to hit.

[Big Fil]

Wow, sorry to hear about the crash. Hopefully the cause of the problem was destroyed in the crash so upon rebuild it doesn't happen again. If it were me i'd dial back the HS until you are confident in the bird. 2500rpm is impressive for something swinging 623mm blades but is definately going to eat itself alive when making contact with the ground.

[th3tick]

Two new pieces of evidence caught my eye today...

The rod end that came out of the CF tube has a slight bend to it. That seems to imply to me that the blade strike may have hit the full CF tube and dislodged the rod at that time. Otherwise I can't explain the bend.

Also, the roller that's above the pulley is extremely notchey. It's so notchey, it barely turns now. It has like two positions it now stops in instead of turning, let alone turning freely. Not sure what it means, but it's odd...


Still confused,
John

[Flybar-less]

John,
Dump the idler roller and install 3-3x8mm bearings instead. Many people have had tight tail belts come off, including me. makes for a scary auto.

[OICU812]

Two new pieces of evidence caught my eye today...

The rod end that came out of the CF tube has a slight bend to it. That seems to imply to me that the blade strike may have hit the full CF tube and dislodged the rod at that time. Otherwise I can't explain the bend.

Also, the roller that's above the pulley is extremely notchey. It's so notchey, it barely turns now. It has like two positions it now stops in instead of turning, let alone turning freely. Not sure what it means, but it's odd...


Still confused,
John

You know for 100% that the roller "idler pulley" was super free and that the bolt passing through it was for sure not too tight? Too tight would and could either burn belt, or cause it to skip off as mentioned.

[th3tick]

You know for 100% that the roller "idler pulley" was super free and that the bolt passing through it was for sure not too tight? Too tight would and could either burn belt, or cause it to skip off as mentioned.

No clue. It's not something I remember checking in detail on assembly. I know I checked most things, but that one I have no recollection of checking. And it seems like an easy thing to over-tighten and miss.

I tell ya, this next kit, the tail will get the fine-toothed comb treatment. That idiot that did the assembly last time wasn't careful enough for me.

I totaled the dollars I had in the air that day, and came to the conclusion that a re-kit is really a cheap way to get off for not being absurdly careful ;)

John

[blueviewlaguna]

No clue. It's not something I remember checking in detail on assembly. I know I checked most things, but that one I have no recollection of checking. And it seems like an easy thing to over-tighten and miss.

I tell ya, this next kit, the tail will get the fine-toothed comb treatment. That idiot that did the assembly last time wasn't careful enough for me.
I totaled the dollars I had in the air that day, and came to the conclusion that a re-kit is really a cheap way to get off for not being absurdly careful ;)

John
Hi John - speaking of total dollars in the air, I have been toying with the idea of getting a similar setup to yours, just off the top of my head I come up with:

**Neu 1912/1Y/H - 300.00
**L600/Flybarless (A Main Hobbies) 1330.00
**Radix 600 main blades 85.99
**JR 8717's 300.00 (for 3)
**GY611/9256 350.00
**AR7000 70.00
**Jazz 80-6-18 300.00
**Flightpower 5350 10S (three @ 540.00) 1620.00
**Rx batteries and BEC 100.00
**Misc support items, crash kit, spares, etc 500.00

4836.00 total

[BruceW]

On the V-bar setup you won't need a gyro since its built into the control unit and you'll want a Jazz 55 instead of a Jazz 80 (limited to 6S).

[terrabit]

Dude, that sooo blows! I feel your pain my brutha. I ended up rekiting after my last crash. I'm definately going to recheck all my stuff pronto. Bummer!

Sidenote; some piro-rate, huh?