T-Rex 600 Losses it Blades

[Video_Feed]

Ooops - well it could have been much worse if they had departed higher or at the wrong angle...

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Added by: Stuart
Tags: T-Rex 600 Losses it Blades
Date: 2011-06-19





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[pgkevet]

..headspeed was a bit outside any design specs?

[robbo45]

i cant belive how fast the blade came out ,they could really hurt if they hit you .as you said lucky it was not higher or doing you fast backward flight

[ROCKET RONNIE]

i had the same thing with my 450, blades hit the side of my van, i was right next to it. s--- myself, em must put lock tight on both sides

[Kwickkwack]

i cant belive how fast the blade came out ,they could really hurt if they hit you

I think that is an understatement, the word death springs to mind

[moyesboy]

I started to discuss this here but now I did a better calculation.
I take the best m4 bolt - UTS 10699.4N (this takes into account the thread, uses the core diameter loaded in tension)
Apply a safety factor of 2 (which is the last I would accept in a life and death situation).
w(speed)=sqrt(F/mr) in rad/sec - a 600D (not the heaviest blade) is 0.125kg at a rad of 0.29m (flybarless blades are heavier!)
=384 rad/sec or 3670 rpm.
That is for a light 3D blade - not a heavier flybarless blade.
Force increases with the square of the speed, but linearly with mass.
If you get to 5000rpm with a 600D, then there is no safety margin and the blades are definitely coming off no matter how perfect the bolt and feathering spindle are!

These calcs are purely the straight pull, and don't take into account the flexing on top of that due to manoevres!

Some of these 12s electric setups sound a lot faster than my 2150 rpm on my nitro - so maybe they are approaching 3000 rpm?

What may be much more important is you should only tighten that m4 screw to about 3 foot/lb, or 4 Nm or you may already weaken the bolt. Don't overtighten the bolt, you must rely on the loctite.
On no account swap that bolt for a stainless steel one whuch will be weaker!

[Lynx.1677]

Wow. That would literally got through a person. Ouch.

[Planehazza]

Ouch! Wonder if the blades were still usable?

[horsham rc]

crazy thats like a flyin samauri sword

[robbo45]

how far do the blade travel when they come off, i only see a 450 and that surprise me how far they went

[acwman]

Had the same thing happen to me on my logo 500. same as on the vid, the spindle bold just snapped at the same place.

It was just an almight 'Bang' and the heli just dropped out the sky. Spent half an hour looking for the blades in the long grasses. Eventually found both of them. One was one side of the field, and the other was on the other, several hundred feet apart.

Only damage was the skids, and the canopy had a few scuffs on it. The blades, blade grips etc were all fine..