Diabolo Down :(

[helinutz]

Out having a great time yesterday with the heli's. Flying the Diabolo and was practicing nose down wall stops when all of a sudden bang and it piled in quite hard.
Pretty certain the culprit is this :-
http://www.minicopter.de/catalog/pro...roducts_id=109
Has anyone had it shatter before, or was I just unlucky.
you can just make out in the picture where it went (you can still see the bolt where it goes through the shaft)
Have also included a pic of what shattered (well the bits I could find)
Stock picture of part for reference
Pretty gutted as its the first crash this machine has ever had. Took out canopy, boom, most of the shafts and a pair of brand new VTX blades
Only saving grace is that the main mechanics and side frames survived reasonably well

[helinutz]

Disassembled and here it is out of the machine

[corrosionate]

Wow. If something were to break in a wall maneuver, I wouldn't have guessed it would be that. I guess I'll try to inspect mine from time to time. I'd be curious to hear if anyone else has broken that piece in a similar manner. I would have expected a stripped gear before that. Bummer man.


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[smsodhi]

It's possible if the bolt was over tightened it may cause this under extreme pressure.

[helinutz]

Its been flying with no issues (and no maintenance on that part) for 2 years.
I suppose theres a possibility the bolt had come a bit undone and the sudden power requirement caused a "jerk" on the shaft that lead to the centre hub shattering.
Don't think I will ever know, but all parts ordered and on their way from Germany, so shouldn't be too long before its back in the air.

[Luvmyhelis]

Yep, lost my own tri 800 a few summers back when mine failed. My bolt was still intact on the shaft and not too tight. I posted up pics in that thread. But the search engine only allows us to go back 4 pages now, or I would have linked it for ya.

[jiminator]

LMH,
If you want all the posts back go to the bottom of the page.There are two drop down menus Sorted By and From The. If you click on From The it gives you the option of Beginning. Click on that and click "Show Threads" you will get all the history back.

[Luvmyhelis]

Ahh,, thanks, search engine was still kinda sketchy. Took awhile. But found it, post 1287.
https://www.helifreak.com/showthread...ub#post6442264

[helinutz]

Well its no longer "Down"
All rebuilt and picked up a couple of canopies from Fusuno. (2nd one works out much cheaper as postage is greatly reduced)
Really impressed with both canopies. They are slightly thiner and lighter, but holes for front and rear mounts are pre drilled and spot on.
Went with the Green Snake, which is one of their standard designs, and also went for a custom "Logo" look alike.
All my other Heli's are Logo's and have that style canopy, and I thought it would be nice to have a matching set, plus I find visibility and orientation on the orange and yellow really good.
Test fly on Wednesday, but hoping no drama's.
Have decided to go back to 750 blades with a slower head speed as well.

[Freeskiken]

Looks really nice !! Good luck.

[helinutz]

Down again 😡
Test ran with no blades, all ok.
Fitted 750 NHP blades, left the canopy off (thank goodness) and popped it into the hover.
All seemed ok, then tried a pirouette, and that's where it all went pear shaped.
Tail dropped and it backed into the ground snapping the new boom, shattering the blades and nicely bending the 3 new shafts I had just fitted.
Even had the forethought to hit rescue, but it didn't make the slightest bit of difference.
Post Mortem results - one of the servo horns had rounded out the splines.
My fault totally as didn't pick it up from the last crash as on the bench the horn bolt had just enough tightness to not notice it, but obviously, with the load of the blades on it, it just slipped on the servo splines.
Pretty pi55ed with myself, but at least it's not major.
Now the question is, do I stretch it to an 800 given I need a new boom,belt and pushrod?
Havnt got anymore 750 blades in stock so I either go back to 710's or buy some bigger blades and have a low headspeed model.
Any thoughts?

[im4711]

Sorry to hear about your mishap. Sometimes I am not happy either when I notice that I missed something

However -> I would simply rebuild and run 710 - 720 mm main blades on it. I run my Diabolo L with 713 mm blades and I am very happy down to about 900 rpm.

[Raptorapture]

Originally Posted by helinutz

Down again ��
Test ran with no blades, all ok.
Fitted 750 NHP blades, left the canopy off (thank goodness) and popped it into the hover.
All seemed ok, then tried a pirouette, and that's where it all went pear shaped.
Tail dropped and it backed into the ground snapping the new boom, shattering the blades and nicely bending the 3 new shafts I had just fitted.
Even had the forethought to hit rescue, but it didn't make the slightest bit of difference.
Post Mortem results - one of the servo horns had rounded out the splines.
My fault totally as didn't pick it up from the last crash as on the bench the horn bolt had just enough tightness to not notice it, but obviously, with the load of the blades on it, it just slipped on the servo splines.
Pretty pi55ed with myself, but at least it's not major.
Now the question is, do I stretch it to an 800 given I need a new boom,belt and pushrod?
Havnt got anymore 750 blades in stock so I either go back to 710's or buy some bigger blades and have a low headspeed model.
Any thoughts?

I've had this happen a few times to me. You'd think I'd learn after the first time. The reality is it can be quite difficult to diagnose the cause once it has happened if the damage is enough. It's a cause and effect thing as it is more likely to be the result of a crash as opposed to the cause.

I find the material of the servo arms have a higher chance of this happening vs harder or more brittle material. There is a tradeoff of course of stripping servo gears vs future slippage in flight after an incident. I now have a regular activity of testing servo arm rigidity whenever on the bench with servos powered whether after a crash or not.

[aziz76]

Man, sorry to hear that. I have made that mistake also.

[trillian]

Oh that's just hideous! I can't imagine how much that must totally bite the big one.

I think I have a pair of those NHP Diabolo blades. I think they're something like 746mm if memory serves.

I'll have to double-check but I'm pretty sure I have them. I bought a pair when Midlands had them and I stretched a Trex gasser but I only flew a couple flights with them so they're still like new.

[Luvmyhelis]

Oh dude, that sucks. I actually downsized my own 8 into a 700 this last season? I like how much more nimble it flies. But the 800 tri was really cool and just a superb heli all around. Depends on what you are after?

[Freeskiken]

Sorry to hear.....

[helinutz]

Originally Posted by Luvmyhelis

Oh dude, that sucks. I actually downsized my own 8 into a 700 this last season? I like how much more nimble it flies. But the 800 tri was really cool and just a superb heli all around. Depends on what you are after?

Had a logo 800 that I liked, but found the disk loading too high for my liking, so was hoping this would be more suitable. Got a logo 700 for "nimble" ��

[Luvmyhelis]

Originally Posted by helinutz

Had a logo 800 that I liked, but found the disk loading too high for my liking, so was hoping this would be more suitable. Got a logo 700 for "nimble" ��

You will find the gearing much better on the Diabolo vs the Logo. Been at the field playing with the new Logo 7, and the gearing is shutting down the Koz 120 esc, (on 12s) so we just installed a new Yge 160 and taking it to 14s to get around the gearing issue. We know it is the gearing ratio as it wasn't doing it in the Synergy 7 with identical equipment, we benched that heli due to rear tt stripping issues. We instantly lost half a minute (3 min now) in flight times with the new Logo vs the S7 (3:30) as it was having to work harder doing the same routine. Great flying heli though, no complaints on quality, but it is tough on the gov. My own 700 tri is running the large Koz motor on 14s and it is just a beast.

[TroyA]

Hey Helinutz,
Is it possible that the slit which was introduced into the hub to help clamp the shaft has subsequently weakened it a bit? Just throwing out my thoughts around a possible cause of the failure.