Micro47G

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[edit] General overview

The concept of coaxial helicopters was first concieved in 1929 by a german engineer who planned to build a tethered, kite-like platform for aerial photography. this first concept was an autogiro rather than a self propelled aircraft.

Later - especially during WWII - more designs based on the concept where tested, mostly without any real application or even success.

The soviet/russian helicopter designer Kamov was the first who produced a fully controlled helicopter using the coaxial rotor design rather than a tail rotor.

[edit] The RC model

When the top rotor is attached by a one-axis pendulum hinge, the whole helicopter is inherently stable, making for a good model to start playing with RC helicopters. A well trimmed coax-heli like the Heim (Graupner) micro47G or Jamara Lama will recover into a horizontal hovering from almost any flight attitude, simply by leaving all controlls alone. However, the reaction to comands made by the pilot are very simmilar to those of a "normal" RC heli.

The Micro47G from the manufacturer Graupner is mechanically identical to the Blade CX/CX2 from E-Flite, but they come with different bodies, landing gears, battery holders and radio systems. There are currently three versions of the so called "Graupner Bell": the version of 2005 (v05, 4990) identical to the Blade CX , the version of 2006 (v06, 4991) identical to the Blade CX2 and the "Jet Ranger" which is also a v06, but with a different body and different battery measurements. The Graupner Models use 35 or 40 MHz FM transmitters, while the E-Flite counterparts come with 2,4 Ghz DSM technology - but other than the transmitters and receivers all spare and upgrade parts are interchangeable, and most modifications apply to both types of helicopters.

One of the main weaknesses of this model is the fixed rotor blade design, turning even the slightest collisions into cases for repair measures. Follow this link [1] to see how to modify the rotors so that the blades are able to fold in to reduce forces of impact thus reduce the chance of breaking blades.

(tbc...)