5 blade cnc head for 450 size helicopter

[scallybert]

The main difference between 3 and 5 blades is the offset of the swash. Where as a 3 blade only needs 45 degrees rotation of the swash, the 5 requires 90 degrees.

Are you sure on that ?

AIUI, the off-set on my 3-blade GAUI is 90 degrees (possibly about 95 on mine).

Here's the set-up manual http://www.gaui.com.tw/pdf/100_3Blades.pdf - which seems to say 90.

It's possible mine just flies wrong, and because I knew no better I thought that's how helicopters flew, and learnt to deal with it...

Mine has no electronic stabilisers, and I think it's quite easy to fly (indoors).

The video of the 5-blade looks like hard work, but it's not clear why.

Head speed seems to make a lot of difference. I think mine is relatively low - hence my lowered gearing.

[Aidi]

My appologies, its the 4 blade which is at 45 degrees not the 3 blade.

As for flying when it setup correctly and the blades are good then its not too bad. The biggest problem with 5 bladers is losing the authority on the tail. Its a case of getting the head speed right, and as you say, the lower the head speed the better

[Butuz]

Something thats always confused me with 3 and 5 blade heads - do you use normal blades? Surely you would have to use blades that are narrower? Otherwise your generating a massive amount of extra lift?

Do you guys cut your blades down or not?

Franky 3 and 5 blade heads look awesome When I do a scale Dragonus 450 its going to have at least a 3 blade head I dont care how hard it is to fly

Butuz

[machasm]

Something thats always confused me with 3 and 5 blade heads - do you use normal blades? Surely you would have to use blades that are narrower? Otherwise your generating a massive amount of extra lift?

Do you guys cut your blades down or not?

Franky 3 and 5 blade heads look awesome When I do a scale Dragonus 450 its going to have at least a 3 blade head I dont care how hard it is to fly

Butuz

The blades are left at the same length AFAIK it is just the headspeed which is reduced.
Adrian.

[Butuz]

Same length but same width also? It's the width I mean (not sure of the technical term).

Either way - if theyre just standard blades then the heli is creating over double the lift? Which would mean half the headspeed? So the bad stability that people talk about is not caused by the head / lack of flybar - it is too much blade area and too low headspeed?

Just trying to understand.

Butuz

[Aidi]

Blades are standard 325mm ones. Nothing special about them at all. As long as they are all balanaced against the heaviest of all 5 then no problems. Others do drop 10mm in length and fly the 315mm with good results.

As Adrian said, you have to lower the headspeed or you start to loose tail authority.

I think the correct term for blade width is its Chord

Rgds
Aidi

[scallybert]

Same length but same width also? It's the width I mean (not sure of the technical term).

GAUI EP100s 2 & 3 blade come with identical wooden blades.

Either way - if theyre just standard blades then the heli is creating over double the lift? Which would mean half the headspeed? So the bad stability that people talk about is not caused by the head / lack of flybar - it is too much blade area and too low headspeed?

EP100 3-blade probably has 2/3 headspeed of 2-blade.

It's kind of nice like that.

The lower head speed seems to make it less skittish (than if you drop pitch and increase head speed.)

As above, you could increase speed and decrease CP if you wanted.

I may have been lucky, but my EP100 3-B was my first ARTF, and pretty much my first non-co-ax heli, and it all worked out pretty well. I'm a bit surprised when people say multi-blades are hard.

However, I am only hovering. I think it will get a bit weird if you fly it, bank it, etc.

Maybe that and outdoors would make it much harder.

Multi-blades and gyro stabilisers sound really interesting. 5-blade EP100...

[Backrowslea]

The chord is an imaginary line from the leading edge to the trailing edge of the blade. the angle of attack is the angle subtended by the relative airflow and the chord line.

More blades will give you more lift and therfore the ability to carry more load (each blade will contribute equally) but it is harder to turn 5 blades at the same speed as 2 as you have more weight and more drag. Lower head speed means there is less torque so the tail still has authority, same head speed with more blades= more inertia more torque and an almost impossible job for the tail.....................If i remember rightly