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Logo 700xx › Heli exploded Logo 700!
04-26-2009 07:36 AM  9 years agoPost 121
helicraze

rrElite Veteran

Victoria - Australia

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So if it rolls slower then it would have less force regardless of blade size?

I am trying to get understanding of what affects what.

I will be looking at excell KASAMA srimok head (90 size) next week, the head will sit higher. Just need to check flybar and ball link sizes etc.

We can eliminate ball link or head block breaking, did you see the pic of main shaft bent? That can't be explained aside from blade being thrown first.

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04-27-2009 05:59 AM  9 years agoPost 122
aaronredbaron

rrApprentice

Champaign, IL, USA

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When you apply a cyclic input, that force is transmitted through the headblock to move the helicopter. The faster the headspeed, and the more aggressive the cyclic input, the stronger that force is. More headspeed and more aggressive cyclic will put a larger load on the head, and even if the disk loading is the same, you are exerting much more force on the head block with cyclic inputs than the shorter blades.

For safety's sake, I would like to see you go with a metal headblock on your stretch. It makes me cringe to see you had it blow up once already and you seem to be going down the same road again. Please keep in mind you are risking anyone around every time you fly it. Maybe nothing will happen. Maybe it will stay in one piece with the reduced headspeed and lighter blades... but why risk it???

two kids? how'd that happen? time to zip'm up!!!

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04-27-2009 06:10 AM  9 years agoPost 123
helicraze

rrElite Veteran

Victoria - Australia

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Thanks, If you read through you will see there was a few issues that increased likely hood of grip failing.

A broken hub cannot explain a bent hardened main shaft that was from imbalance and slamming sideways into the ground.
Anyone bent one of these main shafts?

Now i have dropped the RPM/cyclic/collective pitch to less than that of VBAR strech 700's users so i think its safe. 2050RPM/7deg/12deg
It rolls slower than when i had it in 600 form.
Blades are now 3 grams lighter each, longer shank bolts (have not bent), 1MM spacer each side of root, and above setting changes.

Come on is this the first heli to explode?
READ THE MANUAL, its says do not go above 2000RPM for logo 600, now put your hands up if you run under 2000RPM on 600MM rotors?
What would you all say if it exploded and i was running 600's?

I thank you all for your input. Everytime you fly with any helicopter there is a risk.
I am looking at the full metal KASAMA Srimrok head for 90 size heli.
But think i will just go with VBAR, just waiting on stock and some cash.

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04-27-2009 06:35 AM  9 years agoPost 124
aaronredbaron

rrApprentice

Champaign, IL, USA

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.... good luck, be safe....

two kids? how'd that happen? time to zip'm up!!!

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04-27-2009 07:45 AM  9 years agoPost 125
OICU812

rrMaster

Edson, Alberta, Canada

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craze there has not been once case I have ever seen fwiw with a 600 head exploding with 600mm blades. As you know and as it has been discussed there is a big difference on G force pull between a 600 and 690 blade. Don't ask me why but it never occured to me that you were running the stock plastic head, I know I read your thread about it lots prior, just never sank in as I have not ran a flybar 600 for so long it seems.

...Once upon a time there were Nitros, flybars and frequency pins...

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04-27-2009 10:07 AM  9 years agoPost 126
helicraze

rrElite Veteran

Victoria - Australia

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I know, but i cannot understand what the VBAR head will achieve, would a head block breaking first bend the main shaft like a banana?
The VBAR head has plastic grips too, just alu hub.

I am planning on getting something to replace it.

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04-27-2009 10:13 AM  9 years agoPost 127
OICU812

rrMaster

Edson, Alberta, Canada

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I have never bent a shaft ever in flight, ever 100% truth. I have snapped after a crash but that was the older thinner walled one, the new ones I do not know they are so beefy I would only imagine they would be almost the last thing to snap..

...Once upon a time there were Nitros, flybars and frequency pins...

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04-27-2009 10:46 AM  9 years agoPost 128
OICU812

rrMaster

Edson, Alberta, Canada

My Posts: All  Forum  Topic

I guess my last entry would be this.

Vstabi head utilizes (3) instead of (2) dampers on each side, the chamber body of the Vstabi head being deeper obvioulsy. Thus any side forces induced from large load ie: blades etc would be taken up mostly by the dampers, point one. Point two of course being the hub is metal itself, these forces will not really introduce any flex at all on the hub itself, again to the dampers and being that this is 25%+ on each side of the spindle load there is no really i'll effect. This is best guess based on what I know and have in front of me with both heads. I have no conern at all with my Vstabi heads and 690s. In comparison my Mikado plastic grips are harder to squeeze together then some metal 600 align grips I have here before me to be honest, the Mik grips to me are super strong, I just don't suspect them ever or worry about it to be honest. I know this has been a frustrating thing for you, I feel bad it never clicked into me myself when you were doing the build, I just would never run the plastic head with such large blades myself though no. SOrry for your loss and I hope this is now a good road for you here on out.

...Once upon a time there were Nitros, flybars and frequency pins...

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