RC models with BL motors G15

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By Stefan Gasparin, Martin Hauk

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A model controlled by a small radio system must be light as well - it is necessary for the area load of the model to be low and for the model to be able to fly in an adequate speed. At this point it is perhaps necessary to clarify that we are speaking about models with a span not exceeding 500 mm, because the opinions on what is small vary - as we all know very well - quite essentially. Some people like to misuse such attributes as mini and micro.
The interest in small and light RC models is rising and the development of their components always brings new and interesting possibilities.

A small model features a small bearing area and its weight with equipment must be small as well. Hence, the drive of the model, battery and RC equipment must be special, must feature a low weight. While designing such a model, it is therefore necessary to base the procedure on the weight of the equipment which is available to us. The structure of the actual model must be as light as possible too. After clarification of the model weight presupposed it is possible to design a model featuring a low area load.

I met Martin Hauk of Karviná on the Internet. Martin was searching for a technology of construction of the aerobatic models featuring the least possible weight on a long-term basis, and he has achieved interesting results. Both of us considered what could be possible, and we decided for construction of a less demanding model with less special equipment at first - and in a short time the Hawk Moth model was ready for flying. The technology of construction of his models is clear from the figures.

In this article we would like to inform our readers about what we have achieved with two small and light hall aerobatic models - Hawk Moth and Baby Bee. Their basic data and their equipment can be found out from the table.

  Baby Bee
Hawk Moth
Gasparin motor G10 Micro
G15 5W Wasp
MicroInvent regulator MBC3
MicroInvent propeller MCF4027S
MicroInvent receiver MINOR Flat
SmartServo TOKI RC-1 3 servos
RC-1 3 servos
MicroInvent battery Li-Pol 85P 85 mAh 15C
Li-Pol 170P 170 mAh 15C
Equipment weight  
Weight without equipment  
Weight of accessories  
Complete model weight  
Static thrust of the drive 25 - 27 g, acc. to battery voltage
45 - 50 g, acc. to battery voltage
Flight time 5 minutes
5 minutes
Span 410 mm - monoplane
500 mm - biplane
Bearing area 4,5 dm2
10 dm2
Area load 3,7 g/dm2
3,05 g/dm2

Immediately after the flying-in of the Hawk Moth model, Martin summed up his impressions: "When I am flying with this model, I can feel that I have never controlled anything so slow or even sluggish. It is excellent, one must simply see it, it cannot be described and on a video image it does not create a genuine impression either. I think people will like it very much."
This encouraged us and we started to prepare a project of a smaller model with lighter equipment (Baby Bee). This project was facilitated thanks to the new alternating electrical motor "Gasparin G10 Micro" with an external diameter of 10 mm and new servos "TOKI RC-1" with a weight of 1 g only.
Toki, a leading Japanese firm, introduced on the market small and light servos featuring a weight of one gram only, under the name "SmartServo RC-1", on the autumn last year. The servo is fully useable for controlling small RC models with a weight not exceeding 50 g, designed for hobby flying.

The aim of our work was to verify the usability of the RC-1 servos for the controlling of small and light hall aerobatic models. After the flying-in, Martin was fascinated by the model and he stated only: "It's the insect!" Some video clips from flying with these models can be seen on the Internet. In one of the clips it is for example possible to see how Baby Bee is penetrating, with a hanging motion, through the structure serving for the attachment of the basketball basket board.

Both the above mentioned models were presented, with the interest of viewers, at the international hall contest "CZ Indoor Fest 2008" in Prague. We hope that the figures attached and the table of basic data of the models can bring interesting information about what is possible in this area to all who may be interested in.

RC models with BL motors G15