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.

Helicopters: Blade Tracking

Hi folks.

Over the last several months I have entered the world of R/C helicopters, and what a ride it has been. I have received much guidance and have learned a lot. I want to share as much of this info with others who are just starting out in this hobby to shorten their learning journeys, and hopefully to prevent a crash or two.

One person who has been most helpful is Lood Birk from Ermelo Radio Flyers. He has most graciously sent me several articles that he has written, as well as given me permission to publish them on our blog. A big thank you to Lood. This is the first of those articles.

I encourage you to engage by posting replies to this article - things you agree with, things you would do differently, internet articles you can recommend, links to videos - whatever improves our state of knowledge. Let's hear from you.

Lastly, as all information on this site, this information is provided as is, and you use it at your own risk.

Happy flights,


Blade Tracking

I wish that I had a Rand for every time I have helped a new chopper pilot set up his heli and ask the question “have you checked your tracking”. Every time I get goggled at as if I am the monster from Mars. Well, today I aim to explain to those new guys what is blade tracking, why it is important and how do you fix it.

One thing that you new guys have to understand is that a heli works on balance. If something is longer, short, heavier, lighter or set differently the chopper will begin to become unstable and/or develop an extreme vibration. It is for this reason that blade tracking is important.

So, what is blade tracking? Well, quite simply blade tracking is when the blades are moving in a circular motion and the second blade tracks the first on the same level and plane. Almost like walking in a narrow foot path where you have to follow the person right in front of you in the same path.

So, why is it so important for the blades to track perfectly? As you at this stage will know, the helicopter flies by changing the pitch on the main rotor blades. This changing of the pitch on the main blades causes the blades to start generating lift. This lift causes the chopper to lift into the air. As I said earlier, the chopper is a device that works on balance. In the event that the tracking should be out, blade A’s pitch will be more than blade B’s pitch. This causes blade A to generate more lift than blade B. Because lift causes drag you in effect make blade A’s aerodynamic “weight” more. So now you have the situation where blade A and blade B aerodynamically “weighs” different. What you have done now is unbalanced the main rotor blade and the result is vibration. For those who don’t know. Vibration is BAD for a chopper. Bad vibration can destroy a chopper. I also have seen where bad tracking has made the chopper almost impossible to fly.

So, how do you recognise bad tracking? WORD OF WARNING HERE!! RC helicopter blades are dangerous. Always bear in mind that a blade could break or splinter and hurt you, badly. Ask a friend to help you hold the chopper while you stand back to look at the blade from the side. Spinning blades can appear invisible so be careful not to come to close.

If you spin up the rotor and you see the same as in picture A, your tracking is correct and you can go and fly. On the other hand, if you see what is in picture B, setting will be necessary on the rotor head to correct the tracking.

Most choppers uses the same Bell Hiller control system and should therefore be almost the same to set up.

Firstly what you need to do is get blade tracking stickers (normally supplied with the blades) and paste them about two to three centimetres from the blade tip. This is for you to be able to see which blade is which.

Next, you spin up the chopper, view the rotating disk from the side and see if you can distinguish which colour blade runs high and which blade runs low. OK, now you know which one runs low and which one runs high. Normally you would set the link between the Bell Control Arm and the Blade Grip. On some choppers you set it by changing the length of the link between the Bell Control Arm and the Swash Plate. Your helicopter manual will tell you which one to set.

To set the tracking, set the top running blade’s link to so that the pitch decrease. Use half turns if unsure. On the bottom running blade, set the link to increase the pitch of the blade. Try and keep the amount of turns the same on both the A and B blade’s links. Spin up the rotor and check you tracking. Continue this until your tracking looks like picture A.

So, now you know what tracking is.

Monday, August 1, 2011



Hi Guys


We had quite an interesting wind blowing yesterday. One minute it blew down the runway then it was a cross wind then from the other side. No problem though for fighter command of DDRF. Had a few planes fall out the sky. This gravity thing can be a nuisance at times. I counted (subject to audit from Mark Erasmus) 24 pilots who came through and enjoyed the flying. There was at least the same amount of spectators. Well done guys


We want to wish Roy Starr all the best for his operation that he will be having this week. I trust everything will go well.


This week one of our prospective members managed to get Afrisam to fix the entrance making access to the field so much easier. Thanks guys all assistance with the club is greatly appreciated. But please could I ask that if anyone wants to have something built or done – even if they can arrange it for free or at their cost – to please involve the committee. We would not want things being built and changed and there is no co ordination of how it can get done. Its important that things get don't in an organised manor.


I am told the runway should be scraped this week in which case the irrigation system will follow shortly before the grass is laid. So interesting times. We still have about R20K owed to the club. Please guys we are going to incur some large costs so those who get a statement in the next day or so please make an effort to pay.


Enjoy the pics.


See you all Sunday



Pics- Schalk Burger- DDRF 31July2011

> Hi all.
> Some pics of the birds that fly with wings going faster than their
> fuselages.
> Enjoy.
> Schalk