HeliRush RC Helicopter Forum

A few weeks ago, I had a dream of flying a RC Helicopter and I was totally hooked in when I woke up. So I've decided to build a RC Helicopter without a kit or trainers for my school research project. I have $100 in budget. My aim is to build an RC helicopter without using kits or trainers and keep it at the minimum cost. Currently, I have a rough idea of how helicopters fly and a faint idea of how to build one.

I'm learning to build a fixed pitch helicopter. This is my understanding so far. Please correct me and help me get the terms right.

The blades would be made from wood with the instructions from Wattflyer's guide (http://www.wattflyer.com/forums/showthread.php?t=13397). I have a 52x CD-ROM Drive at home, so I'm thinking of using one of the motors inside for the main rotor. As far as I can understand, the swashplates and the blades would work with each other like Picture 1. The tail rotor runs twice as fast as the main rotor to keep balance. The angles of the blades determine how the heli would tilt.

I have to build the blades by myself. I need formulae and calculations to get done then I can ask the tech teacher to help making one. I'm trying to decipher "WindMission - Basic Blade Design by Claus Nybroe"(http://www.windmission.dk/workshop/Basi ... nleft.html), work/find out the aspect ratio for blades due to the whole thing's weight. I'm not sure whether the Blade Element Theory would be good?

A 52x CD-ROM Drive can have 26000 RPM (from wiki). Would that provide enough lift for the heli to fly up? The final product would be somewhere in the range of 300-500g.

Servos cost quite a lot so I'm thinking of using motors with stoppers place underneath them so they don't move further. The illustration is Picture 2.

One more thing is that I'm new to Remote Controls.

Thank you for your help. Every advices from members and admins of HeliRush would absolutely worth more than a bag of cherries.

Picture 1

Picture 2

For 30% of your budget you can fly one of these;

http://www.brookstone.com/mini-remote-c ... DT|7917825

Probably you can draw an schematic around him. This is a good and simple design for you to learn from.

Look at the weights over the top blade, with that design the heli is constantly adjusting the pitch of the blade keeping the Heli always at level. Also with that design you dont need the tail rotor.

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That's a very nice helicopter. Cheap and Looks sharp. So the lower blades are always moving and no changing angles. Is there a motor attached to the weight over the top blade or the weight is connected to the green board? I mean, how does it constantly adjusting the pitch of the blade? One more to verify: would the 52x Drive provide enough lift for the heli?

Thank you!

I forgot to explain that in the mini-heli example are two motors, one motor for each blade and turning in oposite directions, that's why the heli dont need the tail rotor because one blade compensate the force of the other. You control the tail by changing RPM's in one of the main blades.

The weights on the upper blade creates a centrifugal force that actuates like an automatic leveling system, changing the pitch of that blade each time the body of the Heli experience changes in tilt. The lower blade does not change angles, it has a fixed pitch.

Very interesting topic and beside of being very simple to understand you can write a lot of books about that.

About the 52x Drive I dont know if it will provide enought lift for your heli. There are many numbers that you need to consider, weight and size of the heli by example.

Here a video of the McX;

http://www.youtube.com/watch?v=CILEwZWTIbM


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Helifreak


P.D. Excuse my english, is not my first language!

I want to clarify that I was saying about the lower blade pitch.

It has a fixed pitch but in the McX Heli this is where the controlling (cyclic) servos are attached to be able to move the Heli around.

I'm including a closer look of it;

Hmm... I realized that I have been wrong all the way. So coaxial is completely different to fixed pitch. The illustration in picture 1 is collective pitch. Now I have completely no idea what the swashplate is for. I need a flybar on top to stabalize the heli. So now I'm learning the Bell control system for the flybar for coaxial heli.

I have 2 main questions, say Coaxial is now the main choice:
- if the altitude of the helicopter is now changed by the speed of the rotor, what is the use of a swashplate?
- I have been reading about cyclic control for a couple of days but I can't find how the helicopter move forward. Can someone give me a brief, best with some illustrations just how it works please? Does it work with coaxial at all or does coaxial use completely different settings?

Thanks in advance.

Depending on the heli coaxial collective can be controlled by speeding up / slowing the blades, or the better ones use a swash just like a normal heli.

When the altitude is controlled by motor speed, the swash is used to control the cyclic (left/right, forward/backwards)

Thank you for replying admin. I'm finally sure what I'm doing now. I've made a plan and making a list of stuff to buy, at last.
There're still questions though. For members who own a rc coaxial and those who know, in a coaxial heli, are there 2 ESC, one for each rotor? or is there just one that controls both?

Right now, I'm planning to buy:
Exceed Alpha 300 brushless motors - 2 motors
12A Brushless ESC Volcano - not sure how many
I'm finding a transmitter and receiver that uses 36MHz frequency. I'm looking at the Futaba brand. It's looking promising. Please give me some opinions and recommendations on other brands you can think of.
After working out what components above to buy, I shall find a suitable battery.

And can you also help me with making a plan for the circuit board, the wires and connections between the 2 rotors, ESC, batteries, receiver, transmitter? Should there be anything I need to consider from the above information? Thank you.