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JR Heli Vibe - Airskipper - Sylphide - Venture > Vibe 50 tail exploded,(Build QC)
 
 
Zaneman007
Key Veteran
Location: Texas - USA

The tail on my vibe 50 exploded in mid air?

I'm not sure what caused it? I was banking the heli coming around on a figure eight when I heard a loud cracking sound, followed by a pirouetting heli, and loss of control. The heli fell like a rock to the ground, not pretty.

My flying buddies heard the sound and stated that the blades had appeared to be stopped.

Upon inspection, it was noted that;
* the tail box had been ejected, forcefully
* the tail slider was trashed
* the tail servo was stripped
* the bearing on the tail shaft was dislodged
* one tail blade was totalled
* the pushrod running along the tail boom, was nowhere to be seen.

Although the flybar was bent, there was no noticeable damage to the main blades, not even a dirt scuff. I'm under the impression that the blades had stopped prior to the heli hitting the ground.

I'll try and do a more thorough inspection tonight and get some photos.

any ideas??

I'd rather be flying
06-16-2008 06:08 PM
 
 
tchavei
rrProfessor
Location: Portugal

holy cow. Sorry to hear that. What happen to the set screw that locks the tail case to the boom? I lost a tail blade in mid air and the vibration and resulting crash was spectacular but the tail case didn't move an inch.

Tony


--------------------
"Perfection and patience usually walk side by side..."
06-16-2008 06:20 PM
HOMEPAGE  
 
 
Zaneman007
Key Veteran
Location: Texas - USA

That is the strange part. The screw held, but the hole is now an s pattern about a quarter of an inch long.

I'll try to get some photos posted tonight.

I'd rather be flying
06-16-2008 06:26 PM
 
 
u77171
Senior Heliman
Location: NY - USA

check out the main gear and pinion. If the blades just stopped they may be toast.
06-16-2008 06:37 PM
 
 
tchavei
rrProfessor
Location: Portugal

I believe he was refering to the tail blades stopping right?

If thats the case, the only scenario I can imagine is that somehow the bottom screw of the tail case got loose and that the vibration made the tail case start shifting backwards and cutting a slot in the boom with the setscrew up to a point where the TT become disengaged making the tail rotor stop.

Now the only weak spot in this theory is that you should have noticed heavy vibrations as the tail case started to slip and this shouldn't have happen instantly?

Tony


--------------------
"Perfection and patience usually walk side by side..."
06-16-2008 07:50 PM
HOMEPAGE  
 
 
Zaneman007
Key Veteran
Location: Texas - USA

The main gears look fine. I'm under the impression that the tail blow took all of the energy out of the main blades causing them to stop. The main blades are clean as a whistle.


Sorry for the bad quality of the photo, used iphone and flash light. You should be able to see that the set screw tore through the tail. The tail slider is totally destroyed and the tail shaft bearing is dislodged. There was no headspeed when the heli hit the ground. The damage had have occurred in the air.



I'm a bit baffled by the throttle servo. it is stripped and the rod is bent almost 90 degrees? The tail servo is also stripped.

It appears as if it hit on the front of the heli. The electronics tray cut the battery wires in two, and both sides of the frame are busted forward of the swash.

Again, not sure what happened, but the damage to the tail slider and the tail boom due to the set screw eating it a new b-hole, seems odd. The tail case was pushed out a good quarter of an inch? The main blades are fine. I do not detect a wobble in the main shaft.

I still need to do a detailed breakdown and inspection.

I'd rather be flying
06-17-2008 12:40 AM
 
 
Zaneman007
Key Veteran
Location: Texas - USA

Neither the tail blades, nor the main blades appeared to be spinning. I had no control. It just fell like a rock.

I'd rather be flying
06-17-2008 01:13 AM
 
 
tchavei
rrProfessor
Location: Portugal

First off about the tail pitch slider plate... Buy a set of 5. I had two crashes and both times the tail pitch slider broke just like yours. Its a $2 item and sometimes out of stock so get some spares. You could use the aluminium RJX one but it would probably bend in a crash and cause further havoc. I Rather have the fuse there instead of the servo arm (although your stripped).

About the boom marks... it really looks like the gearbox has been dangling back there before it failed completely. I can't see the set screw causing that S shaped cut instantly nor those shave marks around the boom. A trick I learned to use is to make a small scratch with a scalpel on the boom going over to the tail case and on the other side where the boom touches the frame brace. You only need to quickly look at the scratch to see if the gearbox or boom rotated or backed out during the last flight. This will help you detect imminent failures before hand.

About the main rotor stopping due to the tail rotor... not likely. As soon as the tail rotor is locked, the tail output shaft gear (the little one with 16 teeth or so) is imediately history. I always thought the crown gears would strip in case of sudden stop or impact but no. On my last two crashes the tail output shaft gear is the one that acts as a fuse to save the lower maingear. I seriously doubt that if the tail rotor somehow locked that it could stop the main gear from rotating even in TH because the inertia of the main rotor is so high.

its a damm shame about those frames though. I've been lucky and always managed to crash upright and I'm on my 4th landing gear now but still the original frames. I wonder if the tail servo didn't stripped on impact or maybe when the tail section ejected?

Crashing without knowing what was exactly the cause sucks big time

Did you check the bottom screw on the tail case? Was it still fully in or did it back out?

Tony

PS - Ups, I just realised your tail pitch plate is ok but what broke was the pitch slider. Sorry, I didn't checked the picture correctly


--------------------
"Perfection and patience usually walk side by side..."
06-17-2008 01:15 AM
HOMEPAGE  
 
 
Zaneman007
Key Veteran
Location: Texas - USA

I can't say exactly what happened. It is so much easier when you are the spectator.

I don't know what broke in flight or what busted when it hit the ground. What I recall, is hearing a sound which was followed by the tail spinning. Then the nose started going down. It didn't seem to want to auto and, none of the inputs seemed to have any effect, and it just fell, and made this awful sound when it hit. It was probably still 30 feet up when I hit throttle hold. It must have fell from 100 feet. I like to fly high

I'd rather be flying
06-17-2008 01:28 AM
 
 
tchavei
rrProfessor
Location: Portugal

Update

I just spoke to a fellow pilot (which is involved with JR for some years now) about this and he mentioned that many times (he included) would first insert the set screw and only then tight down the tail case with the bottom screw. This usually proved to be a big mistake because it will give you the false impression that everything is tight when its not. He sais that one should follow the manual exactly because it recommends lining up and tightening down the tail case with the bottom screw and only after everything is square and tight one should insert the stopper to assure that the tail case won't suddently rotate during flight. The set screw gives you a few extra minutes if the tail case starts slipping and trying to rotate but doesn't substitute the main bottom screw.


I'm checking my tail as we speak.

Tony


--------------------
"Perfection and patience usually walk side by side..."
06-17-2008 01:32 AM
HOMEPAGE  
 
 
dhc8guru
Senior Heliman
Location: Texas

[/quote]I'm a bit baffled by the throttle servo. it is stripped and the rod is bent almost 90 degrees? The tail servo is also stripped[quote]

I was gonna ask you how that happened to the throttle rod when I looked at the picture.
I have had servo's strip that were no where near the impact point, I believe its due opposing forces: servo traveling in the opposite direction of when the impact force hits, shearing the gears.

If I am understanding what happened to your Vibe, seems to me that you had something in the tail gear box lock up . Maybe that is why the mainblades may have stopped and the screw shredded the boom.
06-17-2008 08:57 PM
 
 
Zaneman007
Key Veteran
Location: Texas - USA

self imposed damage

It looks like I installed one of the tail gear base plates, backwards. This may have allowed the bearing to slide out and the tail shaft to shift, eat the gears, trash the tail slider, locking up the tail...yada, yada, yada.

I'd rather be flying
06-18-2008 03:05 AM
 
 
tadawson
Key Veteran
Location: Lewisville, TX

I hate it when that happens . . . . my condolences!

- Tim

The more I touch electrics, the more I grow to hate them . . . .
06-18-2008 05:22 AM
 
 
tchavei
rrProfessor
Location: Portugal

Oh my God!

You can see in the first pic that the plate is on backwards. I didn't realized it until you mentioned it. Man what a bugger

I still find it hard to believe that the tail managed to stop the main blades though. The tail output gear (the one that connects to the lower 80T main gear should have stripped immediately freeing the whole system.

Anyway, my condolences

Don't forget to replace the tail output gear shaft, crown gears and the tail output shaft in the tail case even if some of it appears to be good. A crash is horrible but a double crash is heart tearing (don't ask me how I know)

Good luck

Tony


--------------------
"Perfection and patience usually walk side by side..."
06-18-2008 11:11 AM
HOMEPAGE  
 
 
jpla010
Senior Heliman
Location: Auckland, New Zealand

Definitely a sudden stop in the tail would have stripped gears but maybe it was a more gradual increase in friction before it finally locked up. A guy in my club was flying inverted wacking up some grass bushes with his 600N when too much got caught up in the tail and the thing bogged heavily. You could count the main blades as he rolled the heli over. By some miracle he saved it although the pitch slider had almost fully melted through from the friction.

Unlucky with your heli man, but its good you figured out what went wrong so it wont happen again!!

Jonathon
06-18-2008 12:30 PM
 
 
BarracudaHockey
rrMaster
Location: Orange Park FL

Zane, my respect for fessing up, there's quite a few people that would shrug their shoulders and blame the kit, even if they knew dam right well they caused the issue.


AMA 77227
http://www.jaxrc.com
06-18-2008 01:42 PM
 
 
tchavei
rrProfessor
Location: Portugal

jpla010: I suppose that could in fact happen if the lock was progressive. I'm just glad he found out what it was. There is nothing worse than crashing and not finding the problem.

Tony


--------------------
"Perfection and patience usually walk side by side..."
06-18-2008 01:55 PM
HOMEPAGE  
 
 
Zaneman007
Key Veteran
Location: Texas - USA

Lesson learned the hard way

I'm just glad I found the problem. I hate crashing not knowing what happened.

That was an expensive mistake, though. The heli landed on the front right side. With little to no head speed. I know realize just how much of the impact the spinning blades, absorb. The main frames, left and right, are trashed, the base plate is busted, and the top right servo case(DS1015) is totaled. Although, I haven't inspected it the main shaft appears to spin, straight and smooth. This could be a first

The parts count on this kit is high. It is taken longer than I thought to disassemble and inspect, thoroughly.

I'd rather be flying
06-19-2008 06:12 PM
 
 
tchavei
rrProfessor
Location: Portugal

lol

I'm sorry, I had to laugh when I saw your post. Would you believe me that I've railed it in twice hard (once so hard the radix blades broke in 7 places and foam was all over the field) and I've yet to break any of the frames? On the other hand, if I sneeze harder than usual, I'll bend the mainshaft for sure. On my first crash I bent the mainshaft 52 degrees and the second time I railed it in, it was like 28 degrees from strait. I guess each one has is own method of digging into mother earth too

Tony


--------------------
"Perfection and patience usually walk side by side..."
06-19-2008 07:15 PM
HOMEPAGE  
 
 
Zaneman007
Key Veteran
Location: Texas - USA

Terminal velocity

Well, the main shaft and the feather shaft are straight.

Upon inspection, I have to say the cause of the crash was the bearing popping out of the base plate which I installed backwards. This allowed the tail shaft to become skewed, chew on the crown gear, and not allow the tail blade to move to its full limits. The 9254 did strip the gears trying. This appeared to have put pressure on the torque tube causing the tail case to partially dislodge itself (speculation). All of this added friction, causing the main blades to rapidly lose head speed the second I, bonehead, hit throttle hold. This resulted in a total loss of control, and the ability to auto. This allowed the heli to Free Friggen FALL to the ground at 31 feet per second squared, with a terminal velocity when it hit of.......

All guesses welcome.

I'd rather be flying
06-20-2008 01:49 AM
 
 
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JR Heli Vibe - Airskipper - Sylphide - Venture > Vibe 50 tail exploded,(Build QC)
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