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G.K.
Hopping Maniac
Hopping Maniac


Joined: 29 Aug 2012
Posts: 47
Location: UK

PostPosted: Mon Sep 24, 2012 5:27 pm
PostPost subject: Boom strike damage
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As I mentioned in another post, I had a boom strike last week on my HB CP3. This vapourised the horizontal fin, bent the horizontal axis bar, bent the boom and took a chunk out of the leading edge on one blade. I checked the main shaft and that seems OK.

I straightened the boom and the axis, cut a new fin from plastic and re balanced and tracked the blades. I fired up the heli and it flew OK with no noticable vibration. I couldn't say if it handled OK because I have no experience on which to draw.

I had a closer look yesterday as I wasn't convinced that I'd spotted all the damage.

The horizontal axis bar wasn't perfectly straight, when i put an allen key in one end and spun it the opposite blade holder wiggled up and down about a quarter of a millimetre, hardly visible......

I then checked the horizontal axis for play in the center hub and there was considerable play up/down and side to side. The bearings are no longer a good snug fit in the center hub....It looks like the bearing housings have been stretched on both sides, there's no cracks, just stretching.

I'm not sure if this was caused by the original boom strike, if it was caused by a slightly bent horizontal bar during subsequent flying or if it was originally a sloppy fit, which I doubt.

...any way new bits ordered from my supplier (very good job they do), cost £11.00, arriving tommorow. I've probably missed other damage. I'll not fly it anymore until it's sorted. I'll update if it handles any better (I think it probably will).
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tombo242
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Joined: 04 Nov 2008
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Location: Santo Estêvão, East Algarve, Portugal. Now 82, but still feels 22.

PostPosted: Mon Sep 24, 2012 5:37 pm
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Hi Gary,

These are good checks and there is no way that you should have attempted to fly the heli in that condition. Restraining the thought was an excellent move. If anything is not just as it should be the helis search for a crash (they really do seem to do that Evil or Very Mad little devils they are) is increased tenfold.

Tom.
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Burgess
Extreme 3D
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Joined: 27 Mar 2012
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Location: Wales

PostPosted: Mon Sep 24, 2012 7:46 pm
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Hi Gary,

During a boom strike, a lot of energy has to dissipate very quickly and what isn't absorbed via deformation and or disintegration of boom components and or main rotor blades, goes into deforming the feathering shaft, main shaft and blade holders. In doing so also impacts on the radial bearings in the blade holders and main shaft radial bearing too.

If you place a small ball bearing on a sheet on of steel and wack it with a 20oz hammer it will make an indentation in the steel. That's something like what happens in the radial bearings during a boom strike.

So, carefully inspect all those radial bearings, if any clicking or cogging is discernable then replace them, anything less than silk smooth replace.

If cogging is present in the blade holder bearings it effects pitch, if in the main bearings it will effect everything.


Burgess
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G.K.
Hopping Maniac
Hopping Maniac


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PostPosted: Mon Sep 24, 2012 9:41 pm
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I think the bearings themselves are OK although I'll double check. The plastic they sit in seems to have deformed.

I shan't be paying out for the CNC upgraded head parts yet but they will probably be a consideration for when and if I get the hang of this heli. Having said that I suppose the cheaper (weaker) easier to replace plastic head parts do have a sacrificial function, I wouldn't want to have to replace the main airframe for instance.
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Crashagain
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Joined: 17 Jan 2008
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Location: Redding, Northern Calif.

PostPosted: Tue Sep 25, 2012 11:59 am
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A metal head is a good upgrade, but I would recomend running the woodie blades on it while you are learning. the blades will absorb most of the energy in a crash and won't bend the metal bits in the head. It's when you run carbon fiber blades that you will sustain the most damage, since they will transfer the energy thru out the head in a crash.
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G.K.
Hopping Maniac
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PostPosted: Thu Sep 27, 2012 1:22 am
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That makes sense. I suppose minor damage is repairable in wooden ones, provided they're rebalanced......or is it worth it?

Now to demonstrate my complete ignorance of helicopter mechanics:
The new centre hub and horiz axis bar arrived so I took the head apart and discovered that the centre hub has no bearings in it, just rubber "O" rings. No wonder there was play in the axis. Clearly it's supposed to be like that, steering would be a little tricky without it, Doh. Ah well something learned.

Fitted the new horizontal bar and now the heli is flying again. It does hover better or at least it seems to. I shan't bother trying to straighten shafts again. unless they're perfect they ain't right.

Quick question. The controls seem very sensitive on the throttle, I've already removed the ratchet but the difference between a hover and rapid climb seems to be microscopic on the stick. Like wise the rudder trim when hovering, one click and slow spin left, next click and slow spin right.

Reading through other posts it would seem that a better TX would be the solution, something I can program. I'm not keen to go down that road yet.....any other (cheaper)solutions?
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Crashagain
Extreme 3D
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PostPosted: Thu Sep 27, 2012 4:03 am
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Sounds like you need to lower the pitch curve and that will stop the heli shooting upward.
For the tail you can lower the rudder endpoints and that will slow down the tail a bit.
Or you can add some expo.
If you are planning on sticking with the hobby for a bit, you really need to invest in a better radio.
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Crashagain
Extreme 3D
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PostPosted: Thu Sep 27, 2012 4:04 am
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Sounds like you need to lower the pitch curve and that will stop the heli shooting upward.
For the tail you can lower the rudder endpoints and that will slow down the tail a bit.
Or you can add some expo.
If you are planning on sticking with the hobby for a bit, you really need to invest in a better radio.
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G.K.
Hopping Maniac
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PostPosted: Thu Sep 27, 2012 9:17 pm
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Thanks for that crashagain,
The only way I can figure out how to adjust anything on this heli is by adjusting linkages or in the case of the rudder the gain or proportion.....is that what you were suggesting?


Sorry for the dumb questions, if you hadn't already guessed I'm a complete and utter newbie to this hobby.
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Crashagain
Extreme 3D
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Location: Redding, Northern Calif.

PostPosted: Thu Sep 27, 2012 10:49 pm
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Sounds like you can't really adjust anything.
Time to.start saving up for that radio..
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G.K.
Hopping Maniac
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PostPosted: Thu Sep 27, 2012 11:22 pm
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Oh well, maybe at Christmas. Laughing It was a cheap heli after all.
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Burgess
Extreme 3D
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Joined: 27 Mar 2012
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Location: Wales

PostPosted: Fri Sep 28, 2012 2:16 am
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Why not replace the Esky receiver with one of these Spektrum Compatible Receivers to your HB CP 3'Idea'

OrangeRx R610 Spektrum DSM2 6Ch 2.4Ghz Receiver (w/ Sat Port) they're only £3.71, and use your Spektrum DXi6 transmitter. 'Wink'

http://www.hobbyking.com/hobbyking/store/__11965__OrangeRx_R610_Spektrum_DSM2_6Ch_2_4Ghz_Receiver_w_Sat_Port_.html

And give your Esky TX and RX early retirement.

You can then set-up the Honey Bee CP3 to behave just as you desire. 'Razz'

If the mechanical set-up of the tail servo arm and linkage are as described in the manual.

Turn the Gain pot anti-clockwise towards the ‘-' that will soften the rudder response.

Throttle/Pitch response:

Check the position of the cyclic servo arms
Idle Up mode at mid-stick position
all three servo-arms at 90 degrees.

Pitch settings.
3D Mode Idle Up
Throttle stick pitch Degrees
0% - 7.0
50% 0.0
100% + 7.0

Normal mode
Throttle stick pitch Degrees
0% 0.0
50% + 3.5
100% + 7.0

Those are settings given in the User manual.
The 3.5 degrees at mid-stick indicates that the blades might well have a semi-symmetrical foil section.
Most all helicopters will lift-off at around 5 degrees positive pitch.
The blades therefore have a zero rig angle of attack of +1.5 degrees.

Now with the DXi 6 you can dial a throttle curve and all other settings that suit. 'Cool'

Well... its just a thought.


Burgess
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G.K.
Hopping Maniac
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PostPosted: Fri Sep 28, 2012 3:17 pm
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How on earth do they make these things so cheap Shocked

My Christmas list is getting longer Laughing

Thanks for that info Burgess, I 'll have a dig around for an old protractor, see if I can make a pitch gauge. Failing that I'll order one.

I checked the pitch by eye last night. Disconnected motors, with idle up at 50% throttle and it's definitely a few degrees in the negative. The wooden blades would appear to be symmetrical, they are not marked top or bottom and can go on either way..........I've adjusted the pitch by eye and am confident that it's closer to what it should be now. I'll do a more accurate adjustment when I get the gauge. I'll let you know if this improves my lift problem.
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Burgess
Extreme 3D
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PostPosted: Fri Sep 28, 2012 9:55 pm
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I use two pitch gauges it makes life that much easier when alining the paddles and when setting the pitch.

Have you seen this one at Hobbyking, simple adhoc would make it useable on heli blades, then pitch angle could be observed as the throttle is moved. Could always do a Blue Peter.

http://www.hobbyking.com/hobbyking/store/__24884__Control_Surface_Throw_Gauge.html


Burgess
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tombo242
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Location: Santo Estêvão, East Algarve, Portugal. Now 82, but still feels 22.

PostPosted: Sat Sep 29, 2012 1:07 am
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I use one of these, works fine for me and at $0.99 USD can you go wrong?

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9653

Tom.
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