[silkstone]

Originally Posted by Dave

Is the larger model this one ?

That's the baby! Twister Bell 47. Good one to learn on because it's fairly stable. Only 'fairly', mind you.

[Rob Barron]

Is th\at the one they are currently selling on special offer in Maplins for £69? They have a 3-channel RC and are relatively easy to fly because of the counter-rotating blades?

I am seriously considering it so Silky, you reckon?

Cheers,
Rob

[Dave]

3 channels !!! the one I built had 8 .... no wonder I never flew it

[silkstone]

To have full control you need 4 channels:-

Throttle = up and down.
Pitch = tilts the nose up or down so it moves forwards or backwards.
Roll = tilts the helicopter to one side or the other, so it moves sideways left or right.
Yaw = turn left or right.

The three channel 'copters lack any roll control, which means the thing can drift sideways and you can't really hover.

A 4-channel helicopter has a 'swashplate' controling the rotors, like the real thing, which controls the pitch and roll. The 4-channel ones don't have a swashplate - they alter pitch by means of a tail rotor that is in the horizontal plane.

The most stable designs use twin contra-rotating rotors, so there's no need for a tail rotor (except in the 3-channel ones, for pitch control). Yaw is controlled by altering the relative speeds of the two rotors.

Alternatively you can have a 4-channel helicopter with a single main rotor and a tail rotor, like full-size ones, in which case yaw is controlled by the speed of the tail rotor. These tend to be a bit twitchier than the twin-rotor types, and more difficult to fly.

All the 3 and 4-channel models are 'fixed pitch' (FP). Lift is controlled simply by the motor speed, which works fine for models (though not on full-size helicopters).

You can go one (big) step forward and get collective pitch (CP) - 6-channel - in which the angle of attack of the rotor blades can be varied and lift is not directly linked to motor speed. The main appeal of CP is that you can do aerobatics - the helicopter can do loops and fly upside-down. However, it makes them even more difficult to fly, so CP is best avoid by novices like me. Dave - I haven't a clue what all the 8-channels were for unless it had machine guns.

So... Rob - I wouldn't go for the 3-channel Maplin one. Probably the best to learn on is something like the Twister Bell 47 (like mine) or the Esky Lama (very similar indeed). They are 4-channel with contra-rotating rotors, and are about as stable as you'll get. The only drawback is that the rotor span is around 350mm and the model weighs nearly 500g, so crashing into something/someone is a bad idea and ideally you need a large room. Something about the size of a jumbo jet hangar would be good.

The very small models such as the Walkera 5#6 or 4#3 are less likely to do damage but are more difficult to fly. Being so light they are easily blown around by the wash from their own rotors, so you need to be pretty nifty at flying them to prevent a crash.

If you're interested I bought my Twister Bell 47 from Midland Helicopters...

Midland Helicopters Ltd HeliKits_Electric

They also carry a wide range of spares, which you'll probably need.

Tomorrow I take delivery of a Walkera 4#3 which is a tiny single-rotor model and will be impossible (for me) to get the hang of, but I'm a glutton for punishment.

[Rob Barron]

Wow, thanks for all that info Silky, very useful and informative. I now have more to think about before I make up my mind but definitely sounds as though the 4-channel model would be better to learn with. I think I'll wait until summer so that I have a few calm days to get out and try it with. Not much chance of finding a large hall to fly in except my church.... my Pastor would love it but perhaps not during the sermon <g>

I'm now off to look at the site you have linked.

Cheers,
Rob

[Chris H]

All that technical stuff and an apple tree still won.

So is the poor machine airworthy again yet ?