Daily Archives: November 10, 2014


Counterweight made from fishing lead sinkers

C.O.G (Center of Gravity) location is one of the most crucial parameter provided by the model’s manufacturer. The proper C.O.G location enables easy and stable flight. However, some pilot prefer different C.O.G location; deviating from the factory setting in order to obtain unique flight characteristics. They can be nose heavy or tail heavy. In most cases, battery mount location is adjusted to obtain the desired C.O.G.

There are some cases where the desired C.O.G is failed to be achieved, for example when using a much larger and heavier battery or smaller and lighter battery. This might also occur when using FPV models without mounting any FPV gears (just for flying the model). Additional weights called counterweights are used to solve this issue. There are many ways to find additional weight to be used as a counterweight (coins, stones, etc). Solid lead sinkers for casting/fishing are another option.

Fishing lead sinkers

They come in a variety of sizes and weights. You might directly use and load them to your model, or you might want to merge a couple of them into a single shape.

Firstly, the required weight is to be measured or you could try loading some of the lead sinkers to the model until the desired C.O.G location is achieved.

weights

Secondly, construct the mold / die using wooden materials to a desired shape. Cover the internal part of the mold / die with thin aluminium sheet.

Mold

                                      Alu sheet

Finally, the lead sinkers are to be heated until they reach melting point and formed into liquid state. Immediately pour in the liquid lead to the mold / die.

 

Notes : Consult a professional for heating and melting process as the gas fumes from lead is extremely hazardous to human health.

Counterweight

                                Weight loss

“Don’t confuse symmetry with balance.”   ― Tom Robbins, Even Cowgirls Get the Blues


Radio Receiver Antenna Replacement

This is a short tips on radio Rx antenna replacement; in this case FUTABA 2.4 Ghz receiver. Crashes from major to minor ones might cause unexpected damage to your model’s parts. They can be either the model’s airframe or the electronics. One of the examples is the radio receiver or Rx unit which is one of the largest value in your investment.

 

When the model crashed, the Rx unit experienced a considerable huge amount of sudden pull or push force. The mounting Velcro / mounting double-sided tapes might be out of place; pulling the antennas along. The mistake comes when the antenna was secured on the airframe too tightly; the pull or push is sufficient enough to separate the antenna from the Rx unit.

Separated antenna

If we take a closer look at the receiver’s antenna, it requires more than a regular technique to solder the antenna coaxial cable back its header plug to restore the Rx unit back to factory performance.

Coaxial antenna

Therefore, it is much easier and safer to replace the antenna with the replacement parts. In this case, FUTABA provides the antenna replacement parts. The antenna replacement parts come with the header plug, which enable plug-and-play replacement procedure. However, they does not comes with the rubber bobbin ( black rubber ring ); you’ll have to use the originally provided bobbin from the Rx unit.

Antenna replacement parts

Notes : Before disassembling the Rx unit , if your item carries a warranty, opening and attempting your own repair, other than springs and ratchets, will void whatever warranty you have.

Futaba Rx unit

 

 

 

 

The replacement parts can be purchased from your local Great Planes authorized hobby store. Or you may contact directly to Futaba Service Center.

http://www.futaba-rc.com/techsupport/service-center.html

 

Strips of paper on tapes allow the antenna to be fastened in place, but easily remove if the receiver is accidentally displaced from its mounting location during a crash. This will prevent any unexpected antenna damage from a sudden pull or push.

Strips of paper on tapes

      Antenna placement

” Every new beginning comes from some other beginning’s end.” – Seneca