Intro to multi-blade

[Cuppa]

Balance balance, balance, yep and i wiegh each blade on didgi scales too ialso check the whole head on the shaft in a balencer. tracking can be tricky, tho i have a cunning plan to get multi bliade heads track'd spot on all blades first time!, use a section of ali tube (ring) to the diamiter of the flats of your blade grips (top flats) face off on end off the ring on a good lathe, mid stick drop on the ring faced side to contact blade grips and you can see which blade would need to be adjusted if you get my drift, works a treat

[maderdog_1024]

i have tested my 3 blade setup tracking and went on the assumption that the blade grips being level at mid stick was zero deg pitch. it seems to work well.

[Cuppa]

You can also do the same trick with a pice of A4 folded lengthwise and made into a ring making sure the folded edge is paralell this works too here's a go at puttin some picks of my AH64

[Gaza07]

Very nice looking heli almost makes me want a scale one

[pchristy]

To get the initial pitch settings on my Agusta, I found a piece of carbon tube (old tail boom support!) which was a perfect "press fit" between the beanie dome and the flat top of the head.

This gave me a reference at 90 degrees to the main shaft, against which I could use a standard pitch gauge.

It got me pretty close, as on test flying, I had one blade one turn adrift!

Regarding electronic stabilisers, these are probably more necessary with rigid heads than with articulated ones. With a 2-blader, the more rigid you make the head, the better the aerobatic performance, but the more nervous the hovering. This is why F3C pilots pay so much attention to the dampers, as the machine has to be good at both - not an easy compromise to achieve!

The same basic rule applies to multi-blade heads, but with the added proviso that without a flybar, they are generally less "stable" (not quite the right word, but the nearest I can get to describing it!). Multi-blade heads can feel less responsive initially due to their higher inertia, but this is slightly different from stability!

My Agusta feels slightly ponderous on the cyclics in the hover (less noticeable when flying around) but does have a tendency to want to wander about. You work a lot harder in the hover than with a fly-bar model, if you want to keep it in one spot!

With electronics, it ought to be quite easy to tune these tendencies out.

But I build these things 'coz I enjoy FLYING them! I don't want some piece of electronics flying it for me!!!

[RotaryOne]

All round thanks for that, Pete; very helpful and informative, but was particularly interested in this bit.

But I build these things 'coz I enjoy FLYING them! I don't want some piece of electronics flying it for me!!!

Regards

Nigel

[Cuppa]

I must say that a fbl system will not fly the heli for you it is still most nessersary to wiggle the sticks a bit lol unless you perhaps run a heli comand system? anything that would make the heli feel more stable and therefor more enjoyable to fly is an A+ in my book

[RotaryOne]

I must say that a fbl system will not fly the heli for you it is still most nessersary to wiggle the sticks a bit lol unless you perhaps run a heli comand system? anything that would make the heli feel more stable and therefor more enjoyable to fly is an A+ in my book

Undertand that, Cuppa. I am still in the learning curve on this one, as you might gather. However, my impression is there appear to be two basic schools of thought on this subject.

From my perspective as you might gather I was particularly taken by this, copied from response 7 of this thread,

'copterdoctor gives an excellent demo of 5 blade head on T-Rex 600 with MD500 body and without a stabilisation system

http://www.youtube.com/v/unxsvFAM4C8

FROM the thread :
http://www.scalerchelis.com/phpBB2/viewtopic.php?f=7&t=10968 '

and also Pete Christie's comments in the immediately preceeding responses. Then we are into flapping hinges, semi-articulated heads, fully articulated heads and rigid heads. And then there is the Coriolis Effect. Much of this appears to relate more to larger (scale) helicopters than smaller ones, but it is fascinating never-the-less. Follow that with the already mentioned gyroscopic precession and Hooke's Joint Effect -I think I suffer from the latter when I get up in the mornings - and you wonder where it will end. But it does make this whole thing about helicopters and why they even stay in the air so very absorbing.

But back to the thread. I hope I will be able to make some reasonable progress without stabilisation systems given copterdoctor's achievement and comments as well as those of P.C. But time will, inevitably, tell. You will gather that what I am trying to do at the moment is find as much information as possible beforehand.

Thanks for your input, Cuppa

Nigel

[macca221]

I ve done some checking with some freinds and have found that they have had problems with three blade heads but since they have changed to scale blades that i sent them that i got from smartmodels hk there vibrations have decreased dramaticly i am currently flying a 5 blade head with these blades and have had no problems once the tracking of the blades was sorted so the key is obviously to use the correct blades and vibrations are a thing of the past as a matter of interest the blades were $11 us delivered for the five i am using that included delivery and have a years guarantee if you can brake them send them a photo and they replace them free of charge

[RotaryOne]

Thanks, macca221.

That is very helpful indeed.

You've dealt very well with the vibration but what about the stability, given that multi-blades don't have a Bell-Hiller stabilisation system?

Have you done any video clips which can be put on YouTube?

Regards

Nigel

[dannyhough]

Hi all

I'm pretty new to this forum so i hope nobody thinks i'm commenting out of turn.
Have been messing sround with helis a couple of years now and built and flown a couple of 450 scalers with multiblade heads, 4 and 5 blades, rigid and articulated and have flown with and without E stab.

I have to say that although both the rigid and floating head were flyable without and electronic aids (the floating head more so) neither were overly enjoyable to handle.
I fly both P&B and scale and the difference in flight characteristics between the the P&B (flybared) and the scale helis without stabilisation was night and day and flying the 2 back to back isn't somthing i'd want to try again.

If scale were all i flew then i think i would try to relearn flying with the multiblade heads without electronic assistance but as i want to continue with both the FBL controllers were the only way to go and i love flying the scale helis (well heli for now) and it's so relaxing with the 3G helping out where needed.

Guess what i'm saying is that the choice between using Estab and not comes down to what you want from your flying! If you like a challenge, increased heart rate, adrenaline OD and white knuckles (maybe a slight exageration ) then fly without a system and if you want to relax and have it easy fly with.

[RotaryOne]

Thanks, Dan. That is a very useful input.
Regards
Nigel

[Cuppa]

Can anyone help? i'm getting my knickers in a twist with this
5 blade set up on my 600e HIND its so nearly ready to fly.
i just need to know if i understand the set up correctly?
anyone got any good photos of one set up? so i can see
how its supposed to look, think i've confuzed i self 'phazing' doh!
are the link rods (blade grips) supposed to lean into rotation or
back, or infact should be straight parallel to main shaft
any help would be xelent

[dannyhough]

Can you post a picture of the head as there are many variations?

[Cuppa]

not the best photos