Other RC Parts & Components

Information about popular RC hobby parts and RC components.


Introduction To Spread Spectrum Technology

Spread spectrum technology represents the latest advancement in RC radio control systems. This article will show you how spread spectrum technology works, and introduce you to some of the technical terms which you may encounter.

Unlike conventional PPM (pulse position modulation) and PCM (pulse code modulation) radio systems which operate on distinct frequencies, spread spectrum radios broadcast over a large range of frequencies simultaneously. These frequencies are all members of the 2.4 Ghz band, which removes them from the frequencies often used by other communication devices. Because of this, spread spectrum radio systems are already immune to interference caused by non RC radio systems.

Spread Spectrum technology has another advantage though: there is no need for frequency control.
Spread spectrum radio systems broadcast over a multitude of radio frequencies, and the user is never aware of what they are. This works because:

  1. The transmitter is assigned a unique identification code when it is manufactured.
  2. The receiver is programmed to seek and lock to this same code.
  3. After the transmitter is powered on, it encodes the signals it sends with its identification code.
  4. The receiver scans for this code, and locks to the frequencies that the transmitter is operating on.

Each identification code is globally unique, meaning that no other radio system is using it. Because of this, the individual frequencies that the radio is operating on are irrelevant, so as a result an unlimited number of spread spectrum radios can operate simultaneously.

The most noticeable consequence of this technology is that spread spectrum radios are immune to radio interference. Spread spectrum radios also allow an extremely fast servo response time, because the entire encoding, decoding, and execution of radio commands happens in milliseconds.

Spread spectrum technology is becoming more prevelant in RC radio systems, and will shortly replace conventional FM radio systems entirely.

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Phone: 1-800-979-9794 / 306-955-9907
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How To Balance RC Model Airplane Propellers

You should always balance your RC model airplane propellers before using them. Running your RC model airplanes with properly balanced propellers will increase motor or engine lifespan, prevent fuel from foaming, and even extend the life of your electronic components. This article will show you how to balance your RC model airplane propellers using simple and inexpensive equipment.

The best way to balance your RC model airplane propellers is to use one of the many prebuilt balancers available. Blade balancers usually come in two varieties:

  1. finger prop balancers – sufficient for most modelers, you can get good results using a simple blade balancer for 5 to 10 dollars depending on the supplier. Great Hobbies has a balancer which works sufficiently well to balance most model airplane props.
  2. magnetic prop balancers – produce highly accurate results and are usually more expensive than finger balances.

Use the blade balancer by unscrewing the two metal rings and then placing your propeller in between them. Tighten the metal rings so that the prop doesn’t move and support the entire apparatus with one finger tip on each hand. The prop is balanced if it remains motionless. If it tips forward or backward then you will have to adjust it according to the following procedure:

  1. Mark the heavy side (which tips downwards) with a felt tip pen.
  2. Sand one side of the propellers heavy end with medium to fine grit sandpaper. Do not sand the propeller tip – this will cause a dynamic imbalance when the engine is running.
  3. After removing a very small amount of material from the heavy side of the propeller, test it again using your blade balancer.
  4. Repeat steps 2 and 3 until the propeller remains motionless while held in the blade balancer.

This procedure will balance your propeller accurately enough to eliminate the most severe vibration during flight. 3D aerobatics, racing, or other demanding flying requires propellers to be balanced more precisely. You can get a higher end magnetic balancer for 20 to 30 dollars. It’s usage is about the same as the finger balancer except that the propeller is held between two magnets.

Check your propeller’s balance using the above method and be sure to follow the manufacturers instructions when putting the propeller in the balancer.

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© Draganfly Innovations Inc.
Phone: 1-800-979-9794 / 306-955-9907
Email: info@rctoys.com
Web: www.rctoys.com
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How to Play RC Model Airplane Games

There are many fun games that you can play using RC model airplanes. This article shows you how to set up and play some of the most interesting ones.

Aerial Combat

You can simulate aerial combat with your RC model airplanes without excessive risk to your models. Here’s how:

  1. Find as many friends with RC model airplanes as possible.
  2. Divide the available RC model airplanes into teams
  3. Attach different colored streamers to each RC model airplanes tail, depending on which team that it’s on.
  4. Have all the RC planes take off at once
  5. The object of the game is to use your RC model airplanes propeller to cut the streamer off of our opponents.
  6. After a set amount of time all of the planes land and the length of their streamers are measured. The team with the most streamer remaining wins.

This game can be played with any number of RC model airplanes, but keep in mind that the risk of a collision increases with the number of RC model airplanes flying.

Flying the Limbo

This is one of the easiest games to play, but it’s also the most risky. To play,simply find a large football or soccer field and fly your models through the goal posts. Make sure that you are allowed to fly your models in the field that you’re using, and that there are no people in the field that could get hurt -should the airplane crash.You can also construct a makeshift goal post out of PVC pipe, found in most hardware stores. Cut the pipe to a decent length, and then friction fit it together using PVC fittings.

Bomb Dropping

RC pilots frequently modify their aircraft to carry and drop payloads. If you would like to add this ability to your RC model airplane, follow this procedure to construct a launching apparatus:

  1. Find a rectangle of balsa wood, at least as long and wide as the payload that you intend to carry on your RC model airplane.
  2. Horizontally mount a spare servo to the end of balsa wood. Make sure that the servo arm points upwards and rotates 90 degrees when activated.
  3. Stretch a rubber band over the two corners of the balsa rectangle opposite the servo, and then loop the rubber band over the servo horn.
  4. Mount the whole apparatus on your RC model airplanes fuselage, and connect the servo to your receiver.

After the servo moves, the rubber band slips off the horn. If you place your intended payload under the rubber band, you can drop it from your RC model airplane at the flick of a switch. Take a look at this picture, which shows one such design completed and loaded with plastic parachute toys.

You can make bombs to drop out of Styrofoam cups, rubber cement, and talcum powder. Here’s how:

  1. Place one Styrofoam cup on a flat work surface, and fill it with a few tablespoons of talcum powder. Take a small paint brush, and coat the Styrofoam cups rim with a small amount of rubber cement.
  2. Place another Styrofoam cup on top of the first, lining up the rims.
  3. Let the cups dry
  4. Take a hobby knife and cut a cross section into one of the cups.
  5. If you like, spray paint the bomb and add cardboard fins.

After the bomb hits the ground, the cross section that you cut into the nose will cause it to shatter, releasing the talcum powder it contains. When it works, this looks a lot like the cloud of smoke and debris that real bombs leave after exploding. After you drop the bomb, be sure to watch your airplane and not the resulting cloud of powder.We hope that you enjoy playing these games with your RC model airplane. Be safe,and have fun.

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Phone: 1-800-979-9794 / 306-955-9907
Email: info@rctoys.com
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How RC Jet Engines Work

Introduction

RC jet engines represent some of the most impressive technology that the RC industry has ever created. RC jets are always an amazing sight at the flying field, because they look and sound just like the real jets you find at airports and military airfields. In this article, we will take a look at how model jet engines work, and show you the differences from full scale jet engines.

Before you go out an buy a jet, be warned that RC jets are some of the most complicated, expensive, and difficult RC model airplanes available. You will need both many hours of flying experience and a huge budget to successfully own and fly an RC jet.

This article is about real jet engines which burn kerosene (or jet A1), not the electric ducted fan models frequently found in hobby stores. EDF jets are great models to fly, and some are capable of advanced aerobatics, but they are not to be confused with real RC jets using real jet engines.

How Full Scale Jet Engines Work

In order to understand how model jet engines work, it is helpful to examine the full scale engines used by airliners and other jet aircraft. A jet engine is a device which operates inside a fluid (in most cases air), and expels it at high speed achieving a propulsive effect. The mechanics of jet engines are best represented by Newton’s laws of motion, specifically: “For every action, there is an equal and opposite reaction.” This means that the reason jets go forward is because they expel air backwards, faster than it came in. This basic principle applies for all types of jet engines.

But how do we achieve the movement of air needed to propel an aircraft? We know from high school chemistry that the volume and the temperature of any gas are proportional. Because of this, when air is heated, the volume increases. If the air is held in a container (the combustion chamber of a jet engine), then the pressure will also increase. Releasing the heated gas will result in an exit speed greater than the speed at which the air entered, creating the backwards flow of air needed to travel forward.

Interestingly enough, rockets are considered to be a type of jet engine. The only difference between a rocket and a conventional jet engine is that the rocket operates in a vacuum, and thus needs to take both fuel and an oxidizing chemical with it. The discussion of rockets and other exotic jet engines is beyond the scope of this article, so we will limit our investigation to three of the most common designs. These jet engines are listed in order of complexity, and all were used in full scale aircraft at some point in time.

The Pulse Jet

The pulse jet is one of the simplest jet engines, consisting of little more than a pipe and a fuel source. Pulse jets were used by Germany during World War II to propel primitive cruise missiles (V1 flying bombs). A pulse jet works by igniting a fuel air mixture in high frequency bursts. A typical pulse jet cycle operates as follows:

  1. Air is allowed to enter the combustion chamber, and fuel is simultaneously added.
  2. The intake valve is closed.
  3. Ignition is triggered, resulting in an outward flow of air and low pressure inside the combustion chamber.
  4. The valve is opened, and new air rushes in due to the low pressure in the combustion chamber.

This cycle repeats during the entire operation of the engine.

Pulse jets are not very efficient, and are extremely loud. Because of this they are not often used in full scale aircraft, but hobbiests often build them due to their design simplicity and lack of moving parts. In some cases, pulse jets are built to small dimensions and used on RC model airplanes.

Turbojet Engines

More sophisticated jet engines use turbines to compress the air fuel mixture before igniting it. A turbine is a device which consists of sets of moving blades attached to an axle. If the turbine blades are spinning, they will move air through themselves and towards the back of the vehicle. This figure shows a moving turbine, spinning on an axle.

The operation of a turbojet is represented in this figure.

Unlike pulse jets, turbojets lack a repeating cycle (the engine operates continuously). There is a sequence of events that occurs during the engines operation though, so we list them here in chronological order.

  1. Air enters the turbine and becomes compressed.
  2. The compressed air is routed to the combustion chamber, where is is mixed with fuel.
  3. Ignition occurs, and the resulting hot air is allowed to exit the jet engine.
  4. Before leaving the engine, the hot air is forced through a gas turbine, which drives the compressor used in step 1.

Turbojets are far more efficient than pulse jets, because some of the energy produced by the combustion process is reused

Turbofan Engines

Even though turbojet engines are more efficient than pulse jets, they are not often used in subsonic aircraft because of the noise they produce. Turbojet engines are well suited to high speed operations, exceeding the speed of sound. They become less efficient at the subsonic speeds which airliners and other commercial jet aircraft operate at.

The turbofan design operates on exactly the same principle as the turbojet engine, but instead of routing all of the intake air through the combustion chamber a small amount is allowed to exit unburned. Instead of being mixed with fuel and burned, some of the cool air is mixed with the exhaust, reducing the exhaust speed and increasing fuel efficiency. This figure illustrates the operation of a turbofan jet engine:

How Model Jet Engines Work

RC Model airplane jet engines work in exactly the same way as the full scale ones discussed above, with the exception of the air compression. Instead of using an axial turbine compressor, RC jet engines use a centrifugal compressor. A centrifugal compressor propels air outwards after it enters the engine, causing it to hit the engine case and be compressed. Centrifugal compressors need fewer moving parts than axial turbine compressors, and are more efficient for small applications. Many small full scale jets use centrifugal compressors for the same reasons.

Here is a picture of a typical RC model airplane jet engine, mounted on top of an RC model airplane.

RC jet engines operate on kerosene, exactly the same fuel that full scale jet engines use. Ignition is achieved with a small glow plug, like those found on two and four stroke RC model airplane engines.

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Phone: 1-800-979-9794 / 306-955-9907
Email: info@rctoys.com
Web: www.rctoys.com
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APC RC Airplane Composite Propeller Motor Shaft Adapter Bushings Explained

All of the APC RC Airplane Propellers include a set of motor shaft adapter bushings, so that they can be used on a variety of different RC airplane motor shafts. It is important to use the correct adapter bushing so your propeller fits snugly on the motor shaft.

Which Motor Shaft Adapter Bushing Do I Use?

To determine which adapter you should use you have to know the shaft diameter the motor you’re using. For example, if your motor has a shaft diameter of 0.313in (7.95mm) then you need to use the APC adapter bushing with an inside diameter of 0.313in.

Inside Diameters of the Motor Shaft Adapter Bushings

Bushing 1 Bushing 2 Bushing 3 Bushing 4 Bushing 5
(mm) 3.25 4.01 5.00 6.02 7.95
(in) 0.128 0.158 0.197 0.237 0.313
(in) 16/125 79/500 197/1000 237/1000 313/1000

* All the APC adapter bushings have the same outside diameter.

Precision Motor Shaft Mounting Procedure

Precision Motor Mount Adaptation Procedures

  1. Each APC propeller’s hub may be precisely adapted to motor shaft diameters of 0.128in, 0.158in, 0.197in and 0.313in by using bushings 1 through 5.
  2. Remove the desired locating ring by twisting.
  3. Insert the ring with draft angle as shown.
  4. The propeller hubs may be adapted to other shaft diameters by reaming the non-precision 0.250in (1/4in, 6.35mm) hole to the size you need.

Never Drill a Propeller, Use a Reamer Instead

In the instructions that come with each propeller, APC tells customers to “drill to desired diameter”. Never drill a propeller. A drill will make an asymmetrical hole and ruin the propeller’s balance. A reamer will make a perfectly centered hole.

Where to Buy APC Electric RC Airplane Propellers

Draganfly Innovations Inc. has a huge selection of APC Electric RC Airplane Propellers. The three types are Slow Flyer, Wide Electric and Electric and range in size from 6 to 24in.
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© Draganfly Innovations Inc.
Phone: 1-800-979-9794 / 306-955-9907
Email: info@rctoys.com
Web: www.rctoys.com
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The Deans Ultra Plug Connector Pair

The Deans Ultra Plug connector pair is a pair of industry standard electrical connectors for your RC vehicles. These solder on connectors are ideal for use with batteries which do not come with connectors, or the other electrical system components of RC vehicles.

The Deans Ultra Connectors have a very low internal resistance as compared to their competitors (see this post on RCGroups.com). Experiments have shown this internal resistance to be only 91 micro ohms, as compared with 360 micro ohms for a generic brand.

Soldering the Deans Ultra Connector Pair to a battery is easy. Just follow these simple steps:

  1. Strip one wire from the battery. It is very important that only one wire is exposed at a time or you might risk a short circuit.
  2. Tin the exposed wire. First apply a small amount of soldering flux then heat the wire with your soldering iron. Let a small amount of solder flow through the strands of wire. You may need to file down the tinned wire after this step so that it will fit in the female connector.
  3. Tin the connector in the same way.
  4. Slide the included piece of heat shrink tubing over the wire you have just prepared.
  5. Solder the connector and wire together.
  6. Using a small butane lighter, shrink the heat shrink tubing over the finished connection.
  7. Repeat these steps for the other wire.

Use the Deans Ultra Plug Connector pair to connect the different electrical components of your RC model. You can order them in packs of two and four on our website.

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Phone: 1-800-979-9794 / 306-955-9907
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Introducing the New Sport BEC – Power All Your RC Model Radio Systems

The Sport BEC is a high capacity switch mode BEC (battery eliminator circuit) for RC models.

One of the main features of the Sport BEC is that it can provide two levels of voltage to your servos. A small switch on the side of the Sport BEC lets you choose either a 5 volt output, or 6 volts for greater servo responsiveness, speed, and torque. This is great for RC helicopters, which need the servos to operate as fast and crisply as possible.

The Sport BEC connects to your electric system between the ESC (electric speed controller) and the receiver, so that you don’t need to disable your ESCs BEC. Just plug the Sport BEC in and fly.

Many ESC BEC ratings are inaccurate, because the capacity of the BEC goes down as the pack voltage increases. This means that your servos might not be getting enough power if you use a high voltage battery. The Sport BEC eliminates this problem and is capable of an output voltage of 3.5 amps when using up to an 8 cell battery. This is enough current to power up to 8 standard servos or 6 digital servos.

The Sport BEC can power almost every kind of model aircraft servo, including digital, standard, and micro servos. If you are using the Sport BEC with micro servos, be sure to set the voltage to 5 volts, or consult the servo owners manual. Some micro servos can be damaged by 6 volt power.

The Sport BEC has been designed to minimize radio interference, but we recommend that you place it at least 2 inches away from the receiver and antenna.

Use the Sport BEC to power the radio system of your nitro conversion plane, robot, or other RC vehicle. It also makes a great replacement for the low current BECs built into most ESCs.

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© Draganfly Innovations Inc.
Phone: 1-800-979-9794 / 306-955-9907
Email: info@rctoys.com
Web: www.rctoys.com
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