RCtoys.com has been selling the MASH rescue helicopter by E-flite for a few months now, and it’s turned out to be a great little scale helicopter for indoor flight. The MASH helicopter looks great in the air and handles better than most co-axial RC helicopters out there. It’s also got a fair bit of weight, making it great for flying outdoors in low winds. The MASH helicopter is so easy to fly that it’s perfect for anyone who’s new to RC, but sometimes we make mistakes and the helicopter can require repair.

If you’ve crashed your MASH helicopter and need new rotor blades, grips, or even a new flybar then you’re grounded until new parts arrive. Enter the crash kit – a carefully chosen assortment of the most commonly needed replacement parts, all in one convenient and discounted package. If you keep one of these on hand, you won’t have to stop flying and wait for new parts in the mail again. The MASH helicopter was designed to be user-serviceable just like larger fuel and electric helis. If you’ve got a broken part, then it’s almost certain that it can be replaced without anything more complicated then a screwdriver. This guide will walk you through replacing the most common parts:

Replacing Main Rotor Blades

The main rotor blades can become cracked in a severe crash and pieces can break off. While it’s completely possible to fix small cracks and dings with some medium CA glue and accelerator, this can negatively affect blade balance and make the helicopter vibrate. It’s easier and faster to replace the old blade so here’s how to do it:

1. Get a small Phillips head screwdriver and unscrew the single aluminum screw at the root of the damaged blade. The blade will now be free, and you can remove and dispose of it. Damaged blades can be sharp, so be careful not to cut yourself.
2. All the top rotor blades come with a white warning label on their upper surface. Choose from the upper and lower rotor blades as needed so that the rotors look like this when viewed from the front. As viewed from the front, the right top rotor blade should curve upwards and the bottom right rotor blade should curve downwards. This picture shows the correct blade orientation.
3. Install the replacement blade and tighten the screw just enough so that the blade swings freely when you tilt the helicopter, but is secure enough that it won’t fly off. This has to be done by feel – it’s not critical that the screw is perfectly adjusted, but the blade should feel secure and move freely.
4. Repeat this for any other rotor blades that need replaced. It’s helpful to install them one at a time to keep track of the orientation.

Replacing the Blade Grips

The blade grips / holders are black clevis like objects which clamp down on the root of each blade and hold it to the main shaft. If one of these becomes damaged, use this procedure to replace it:

1. Remove the both of the rotor blades that the blade grips are holding by following the instructions above.
2. Lay the helicopter on its side and observe the two screws that hold the blade grips together and on the main shaft. This picture shows one screw removed, viewed from the bottom of the helicopter.
3. Unscrew the blade grips and keep the screws in a safe place where they can’t roll away.
4. Replace the broken blade grip and install the screws.

Replacing Ball Linkages:

Ball linkages connect the RC helicopter’s servos to the swashplate and flybar. It’s fairly unlikely that these will get broken in a crash, but if they do, here’s how to replace them:

1. Snap off the damaged ball link using your fingers or a screwdriver.
2. Find the replacement link that matches the one you took off and press it on to the spherical plastic nubs where the broken link connected. This picture shows a partially disconnected ball linkage on the flybar:

What makes the MASH helicopter unique is its ability to be completely disassembled and user serviceable. You don’t usually find this on helicopters in the 100 to 200 dollar price range, which are usually meant to be flown and then discarded when they break. Want to learn more about the MASH helicopter, or get one to fly around your living room? RCtoys sells them at a great price. If you just want the crashkit, RCtoys.com has that as well.

The swashplate isn’t included in the crashkit, because it rarely breaks.  If you need a replacement swashplate, you can get one online for a low cost.

The helicopter became a prominent military asset during the Korean conflict of the early 1950s. The United States Army started using helicopters for medical evacuation in order to increase the survival rate of critically wounded soldiers. Helicopters were used in conjunction with forward mobile army surgical hospitals (MASH units).

When many people think of helicopters being used for medical evacuation in Korea the Bell H13 Sioux (designated the Bell-47 by the US Army) is the one that most comes to mind. Most people know this helicopter as the MASH helicopter because of its important role in the TV series MASH. EF has come out with an amazing flying replica of this famous MASH helicopter.

Included with the EF MASH Rescue Chopper

The EF MASH Rescue Chopper includes everything you need to fly, right out of the box. This is what is included:

• 2.4 GHz 4 Channel Transmitter
• RTF MASH Rescue Chopper
• 7.4v 800 mAh LiPo Battery for the Helicopter
• Two 7.6 gram Micro Servos
• 3 in 1 2.4GHz receiver

Main Features of the EF MASH Rescue Chopper Indoor RTF RC Electric Helicopter

The EF MASH Rescue Chopper is easy and fun to fly while still maintaining the stand off scale looks of the helicopters used in the TV series MASH. The dual rotors (co-axial) make this micro electric helicopter easy to fly and perfect for the beginner RC helicopter pilot. Experienced helicopter pilots can work on there skills to make the flight look as realistic as possible.

It is very quick to get the EF MASH Rescue Chopper ready to fly. All you will need is a screw driver and 8 AA batteries. The MASH Rescue Chopper Indoor RC electric helicopter does require a small amount of assembly. Before you begin the assembly start charging the LiPo battery. This way you will be flying the helicopter in no time.

This mini indoor electric helicopter has a coaxial rotor design which provides great stability, and eliminates the need for a separate tail rotor to control torque induced yaw (rotation around the main rotor axis). Coaxial RC electric helicopters are great for flying indoors, because they are both stable and offer precision control.

A 3.7 volt LiPo battery powers the EF MASH Rescue Chopper for a flight time of eight to ten minutes. The battery is charged in the controlled and takes about 30 minutes to charge. To get maximum enjoyment out of your helicopter it is a good idea to buy a spare battery for it. This way you can be charging a battery while flying and cut down your down time.

If you do happen to have a mishap and crash the MASH Rescue Chopper you will be amazed at how incredibly resilient it is. However things do and can break, but not to worry as a full line of inexpensive replacement parts are also offered for this helicopter.

In summary if you want to try some basic scale electric RC Helicopter flying you should look into buying the EF MASH Rescue Helicopter.

Lithium Polymer batteries are currently considered the best electric power source available for use in electric rc helicopter kits. The reason for this is that lithium battery packs are significantly lighter than NiMH or NiCD packs, and have higher capacity for the same size. Over the last five years they have worked their way into the hobby market, and in addition to being used in electric rc helicopter kits they are also common in rc boats, cars, and airplanes. Their low weight and high capacity make them ideal for long flight times, while also providing more power.

Understanding Lithium Polymer Battery Specifications:

Lithium Batteries are also know as LiPo, Li-Po, LiPoly, and Li-Poly. What do all the lithium battery specifications mean? The values that are the most important are:

• Pack voltage (depends on cell count; each cell is 3.7 V)
• Capacity (mAh)
• “C” rating (describes the rate at which power can be drawn from the battery)

Lipo Battery Cell Voltage

The nominal voltage of each cell in the pack is 3.7V, but this can go down to 3.3V during discharge, and up to 4.2V when fully charged. A battery pack is composed of two or more cells put together in series for increased voltage, or in parallel for increased capacity. A 2 pack with 2 cells in series would be rated at 7.4V (2x 3.7V).

The battery pack configuration is denoted by the number of cells in series and the number of cells in parallel. A 3s2p pack would have three cells in series, and 2 cells in parallel, using a total of 6 (3×2) cells. A 4000mAh 3s2p pack would have a capacity of 4000mAh (2 x 2000mAh), and a voltage of 11.1V (3 x 3.7V). It would internally consist of six 3.7V 2000mAh lithium polymer cells. The cells would be doubled up (the 2p part of 3s2p) to get 4000mAh, and there would be three in series (the 3s part of 3s2p) to get 11.1V (3 x 3.7V).

The “C” Rating

The “C” rating describes how quickly a battery can be discharged. A 2000mAh LiPo battery with a “C” rating of 1C continuous would mean it should not be discharged any faster than 2000mA or 2A, which would take one hour. A 2000mAh pack rated for 12C continuous would be able to discharge at 12 times its capacity (12 x 2000mA = 24000mA or 24A) at which rate it would discharge in 1/12th of an hour. Using a pack with a higher C rating than you require will leave some room for safety, and extend the life of your battery.

Continuous Current:
If you know how much continuous current will be drawn and the capacity of the pack you want to use, you can easily determine what C rating you require. If you are drawing 5A from a 1320mAh pack, simply take the current and divide by the capacity: 5A = 5000mA, 5000mA / 1320mAh = 3.8C.

Burst Current:
LiPo batteries are also given a C rating in terms of burst, which is how quickly the battery is able to discharge for a short time. A burst rating of 20C would mean a 2000mAh battery could supply 20 x 2000mA = 40000mA or 40A for a few seconds.

Selecting the Best LiPo Battery for Your RC Helicopter

To select a battery for your rc helicopter, you first need to know what voltage you require and how much current you will be drawing continuously.

• If the motor in your rc helicopter is rated to work with 11.1V, you would need a 3 cell battery.
• If you need to draw 20A, and you would like your rc helicopter to have a 10 minute (1/6th of an hour = 6C) flight, you would need a battery with 20A / 6 = 3.3A = 3300mAh.
• This means you would need to put a 3s 3300mAh battery with a C rating of 6 or higher in your rc helicopter.
• Thunder Power RC has a LiPo battery for almost any electric RC helicopter.

Always Remember These LiPo Safety Instructions

• Remove the battery pack from your rc helicopter before charging.
• Only use chargers designed to work properly with lithium polymer batteries.
• Always place your LiPo on a fire-proof surface while charging or use a LipoSack.
• Never leave your battery unattended while it is charging.
• Never charge a lithium battery if it is below 3.0V per cell.
• Never charge a lithium battery that is puffed up, or damaged in any way.

Your electric RC helicopter power system is a combination of battery, speed controller, and the motor that drives your gearbox and rotor blades.

The battery supplies the power. RC helicopters have used Nickel Cadmium (NiCd) packs, Nickel Metal Hydride (NiMH) packs, and the newer, lighter, and more powerful Lithium Polymer (LiPo or LiPoly) battery packs. All of these are rechargeable and can be used over and over.

The electronic speed controller (ESC) is the component that interprets the control signal coming out of you radio receiver (RX) and passes battery power to the motor to make it run at the speed you want. Speed controls are available for brushed motors with two motor wires, or for newer brushless motors with three motor wires.

The motor is the final component that converts the electric power to mechanical power. Brushed motors are less expensive, but less powerful. High performance helicopters tend to use newer brushless motors.

An example of a compatible RC helicopter electric power system is:

• LiPoly Battery: Thunder Power Pro Lite 3s1320
• Brushless ESC: Castle Creations Phoenix 45
  
• Brushless Motor: Hacker A20-6XL RC Helicopter Motor