Thursday, August 4, 2011

Helicopters: Starting Out

Getting in those helis

By Lood Birk

Ermelo Radio Flyers

Ok, firstly a bit of a confession. When I started out, I did all the wrong things and so I write this article for you new guys out there.

You have seen them in the hobby shop. You have seen them at the field. You have seen them fly and now you want one. You want a heli right now!

Whoa there cowboy! I need you to sit down take a deep breath an listen to what I have to say. Even though helis are one of the most rewarding RC aircraft to fly, it needs to be approached with caution and respect else, it will be a nasty shock to you bank account and not to mention your ego.

Firstly, a word of warning. No RC plane is a toy. Especially so with choppers. I call them flying saws and with good reason. So my advise is that whatever you decide to do after this article, seek advice from a RC flying club or a well established hobby shop.

Let us start at the beginning. There are basically four categories of choppers you get on the market today. They are as follow.

1.Toy choppers

2. Coaxial choppers

3. Fixed Pitch choppers

4. Variable pitch choppers

I am going to explain these four categories for you and then I am going to explain how it all fits together and what I suggest you do.

Toy Choppers

Oooo, do I have a bee in my bonnet about those. Why you may ask. Well the problem with toy choppers is that they generally do not fly well. They look on the outside like a proper coaxial chopper, but the are not. Coaxial, what is that? Coaxial simply means that the chopper has two counter rotating main rotor blades. The counter rotating main blades eliminates the need for a tail rotor and generally are very stable. That in itself is not the real problem. Most of these cheap toys that you normally buy on the flea markets have control layouts on the transmitters that teaches you, the beginner, all the wrong control movements. The reason for that is mainly that these little choppers do not have a swash plate of sorts and reacts totally different than a chopper with a swash plate would. A big difference is that the chopper does not have any forward/backward and let/right motion controls. Further more, you do not get spares for them. Well, you just don’t and when you start to learn the art of missing the ground with your chopper, you will need to be able to buy spares. These little choppers are only designed to fly indoors and any breeze will yield them uncontrollable.

Having said all that, these little choppers are good for just having fun and because they are small are suited for children as the chances of an injury are almost null. Below is a picture of a typical RC to heli. Notice that it has no swash plate. This is the reason for the small little rotor on the tail. It has no side to side movement capabilities and forward and backward motion is controlled by the small horizontal tail rotor.

Coaxial coppers

Ever heard of the Llama? Well, this is where many a fine heli pilot started his career. The first coaxial chopper was a replica of a real chopper called the Llama and soon all coaxial choppers was called Llamas as a description to being a coaxial chopper. So what is the difference between the toy and coaxial chopper and this on? The big difference is that it has a swash plate. Now what is so big about the fact that it has a swash plate? Well, the fact that it has a swash plate means that you can give directional input on your main rotor blade. In short this means that the chopper has left, right, forward and backward control caused by the main rotor. This is pretty much the same as what you would find on the variable and fixed pitch choppers and thus the perfect chopper to start off with. To top it all off, there is a separate control for the rudder (tail) of the copper as well. Same as with the bigger choppers. As you can see, the coaxial, or Llama, chopper teaches you all the control inputs a professional chopper would. More on that later. This little chopper can be flown outside when there is no wind.

As an added bonus, if you select the right chopper, spares will be abundant and cheap. Exactly what you need to get started. Below is a picture of a typical Coaxial or Llama chopper. Notice the swash plate on the main rotor shaft. Also nitice that unlike the toy chopper, it has no rotor on the tail.

Fixed Pitch Choppers

A while back, this was the only option to move towards when starting to fly. Thinking back even further, it was the ONLY option when you wanted to learn how to fly. The fixed pitch chopper precedes even the Llamas.

These little choppers had a tail rotor, like a normal chopper, that was normally driven by it’s own electric motor situated on the tail. The big thing about this chopper was that it had a swash plate, but the main rotor blade’s pitch was fixed. So it could do side to side and forward/backward movements as well as you had control over the tail. So how did it climb and descend? Simply by changing the speed of the main rotor. Later models even had rudimentary gyros that could hold the tail for you. When the variable pitch choppers became affordable and flyable, the fixed pitch choppers pretty much disappeared off the market. Lately though people like E-Flite and Nine Eagles has brought them back on the market as micro helis. These chopper can be flown outside when there is no wind. Below, an example of a fixed pitch heli. Notice the fact that it has a swash plate and a vertical tail rotor.

Variable Pitch Helicopters

This is more than likely the choppers you will see lying outside at the club. They range from small, like the HK-250 till quite large like the JR Voyager, which has a rotor diameter of almost 2m. These choppers also has a swash plate, but the difference is that the rotor speed now is set to be as constant as possible (normally around 2000RPM) and the rate of accent and descend is controlled by changing the pitch of the main rotor blades. This is done by sliding the swash plate up or down the main shaft. The swash plate in turn is connected to the main rotor blades. The tail rotors on these shoppers are normally driven from the main engine via a belt or a drive shaft. The always have a decent gyro to control the tail for you and do not come with 4-in-1 controllers like the Llama or the fixed pitch choppers. Depending on the size of the chopper, it is mostly flown outside and the bigger choppers can be flown in quite a brisk wind. Below an example of a variable pitch chopper.

Now I know that by this time you might be asking me why are you telling me this. This article is supposed to be about how to go about starting on RC helis. Well This information is quite relevant. You need to know the differences between the helis so that in the explanation that follows you will know what I am talking about.

Now. When you start flying choppers, you need something that is stable, forgiving, easy to fly and cheap to fix. For this the Llama is the best option. To try and explain to you the difference between flying the coaxial heli and a variable pitch heli I am going to draw on an example given to me when I was starting out.

Take a round bowl and place a ball bearing into the bowl, like the picture below shows.

Now shake the bowl and let the baring move around. If you stop shaking the bowl, the bearing will return to the centre of the bowl. This is what the Llama does. It has built in stabilization that will return the chopper to a standard hover if you center the controls. For a beginner that is exactly what you will need.

Now let’s see what happens if we turn the bowl around and balance the ball bearing on top of the bowl, like so.

As you can imagine, to balance the ball bearing on the top of the bowl is going to require some practice and skill. Even though it is a bit exaggerated, it is pretty much the way it is with variable pitch choppers. Don’t be frightened now. Flying variable pitch choppers is doable for everybody. But the correct steps needs to be taken.

Another thing that should be on your wish list is a proper simulator. There are various simulators that is downloadable for free off the Internet, but I would suggest rather look at a professional one that has the proper physics programmed into the simulator as well as have the option to be upgraded and download new aircraft. A simulator, along with your Llama and/or your variable pitch chopper will have you zooming thought the air in no time.

When you stand in the hobby shop to buy your chopper, try and buy one that is a well known make. One that you know that you will be able to get support on and whose spares are affordable. I have seen many new flyers make that mistake. They buy the first and best heli and then sit with the baked potatoes.

So to sum it all up in one paragraph.

Start at the bottom with a stable heli like a Llama. Stay away from the RC toys. Get a chopper that has ample of support and has spares readily available. Use a simulator along with your chopper and most of all, have fun.

Happy landings.


Schalk Burger said...
This comment has been removed by the author.
Schalk Burger said...

For another opinion on the different types of helis out there, and on how to start, begin here:

August 4, 2011 6:08 PM