The "Moins que Rien"
a 8,9 gramme (1/3 oz) Indoor R/C plane

The "Moins que Rien" is, as its "big brother" the "Deux fois Rien", an Indoor R/C electric monoplane, powered by a rechargeable Ni-Cd 50 mAh cell, and with a carbon structure covered by a 2 microns mylar film. It is controlled on 3 proportional channels (motor speed, elevator and rudder) by a standard PPM FM transmitter, with a single conversion receiver and a plug-in crystal (minimum channel spacing between to models: 10 kHz). all the electronic is home-made; the receiver and the ESC (and the propeller) have been designed by Jean-Marie Piednoir, the actuators and the DC/DC converter (and the gearbox) by Jean-Yves Martin.

Obviously, this is an unique prototype; among the 4 electronic units (Rx, ESC, converter and amplifiers for the actuators), only the receiver is made on a PCB.

First presentation in Achères on Feb., 6th, 2000.

The marvel is disclosed to an amazed public...

...and they just cannot believe it !

"F-LMQR, you are cleared for take-off, no wind."

2 minutes and 5 seconds later we had to celebrate !
The Champagne glass also has a Pied noir ("Black foot").

How to go from "Twice nothing" to "Less than nothing" ?

Hereafter is the recipe, to avoid you to have your eyes damaged by looking too close at the pictures on the screen:

The secret revealed at Sinsheim on March, 12th, 2000.

At 3.73 g, the 50 mAh Ni-Cd cell represents 37 % of the total weight for a 10 g plane. For sure, it is the first parameter to work on when trimming down the weight of the "Moins que Rien".
Starting from a standard 50 mAh Sanyo cell, Jean-Yves firstly removed the plastic sleeve and carefully machined the external case, getting a 2.85 g cell (the blue colour is just ink, to mislead the spies at the Achères meeting!). Later on, for the Sinsheim's exhibition, he totally removed the case and put the internal part into a plastic case he made himself. Impossible is not French!
And this is how the "2xRien" at 10.68 g became the "Moins que Rien" at 9.8 g and 8.91 g.

Note: Use described here is out of the scope of normal use of this battery and you may apply it to your own needs only if you solely take the responsibility. The author is not responsible in case of accident.

From left to right, the 3.73, 2.85 and 1.96 gramme cells, giving total weighs of 10.68, 9.8 and 8.91 grammes respectively.

Mass analysis:

Technical data:

  • Completed wing: 1.16 g
  • V-tail: 0.36 g
  • Sub-total for wing + control surf.: 1.52 g
  • Fuselage: 0.98 g
  • Gear + 2 wheels: 0.24 g
  • Sub-total for fuselage: 1.22 g
  • Motor and gearbox 1/22.8: 0.97 g
  • Prop. 150x100: 0.32 g
  • Sub-total for motorisation: 1.29 g
  • ESC special JMP: 0,2 g
  • Rx special JMP FM 41 MHz with quartz: 1.31 g
  • 2 servos (actuators): 0.66 g
  • Control links: 0.3 g
  • DC/DC converter: 0.45 g
  • 1 x 50 mAh battery: 1.96 g
  • Sub-total for radio: 4.88 g

Name:

Moins que Rien

Author:

J.Y. Martin

Type:

Monoplane

Wing span (mm):

540

Length (mm):

420

Wing area (dm2):

8.2

Mass (g):

8.9

Mass (oz)

0.31

Wing loading (g/dm2):

1.08

Wing loading (oz/sq.ft)

0.36

Motor:

4x12 mm coreless motor

Gearbox:

1/22,8

Propeller:

JMP 150x100 mm

Servos:

Actuators

Speed-controller:

JMP-France special

NiCd battery:

1x50 mAh

DC/DC converter

1.2 to 5 Volts

 

TOTAL: 8.91 g

 
  • Structure, receiver and servos: 5.01 g
  • Motorisation, speed controller and battery: 3.90 g

More data:

- The ESC is a 3 kHz type (JMP5 "light") and not, as on the "Magicien d'Oz", a 66 kHz HF type (JMP9 HF) which would have required 2 micro-controllers instead of one.
- The DC/DC converter deliver a 5 V regulated voltage for any input voltage between 0,9 and 1,3 V. Associated with the slow flight speed (4 km/h - 2.5 mph), this "high" voltage allows the use of high impedance actuators which can be then directly powered by the micro-controller outputs. This also provides an astonishing power for a so light motor setup ( 0,97 g). The static thrust is 5 grammes for a 180 mA current at full throttle (1800 rpm with the 150 mm propeller). The minimum take-off run is less than one meter.
- The power consumption is around 7 mA for the receiver, 3 mA for the ESC and 20 mA for each actuator at full deflection. At full throttle, the battery current is 1 A (with 1,2 V) and therefore, NiMH or Li-Ion cannot be used at the present time.
- An additional advantage of using a regulated voltage is that the motor speed does not decrease when the battery voltage goes down. "Touch and goes" are still possible until the last seconds. The converter inhibits the ESC when the battery voltage is under 0.9 V.

Et Voila, you know everything, almost everything...

Who is the "French Twisteuse Team" ?

The "French Twisteuse team" originally consists of 3 people: Gérard Jumelin, Jean-Yves Martin and Jean-Marie Piednoir. As for myself, Jean-Michel Quetin, I am acting as the Web promoter for the exploits of these three famous celebrities...
At the beginning, Jean-Marie Piednoir and Gerard Jumelin are both very fond of Horten wings. When Gerard decided to build an indoor Horten wing, Jean-Marie proposed a flexible wing without elevons. After many tentatives, the famous "Twisteuse" was born. Jean-Yves Martin, immediately fascinated by this model, built the third prototype. The "French Twisteuse Team" was born.
You know how the story went on. An extraordinary collaboration between these three specialists, certainly among the best ones in France, then gave birth to, among other things, the "Magicien d'Oz", the "Deux fois Rien" and the "Moins que Rien".

Voila, now you really know everything, really almost everything =:)

If you really want to know everything (tricks, building technics, etc...) please refer to issues #230 (June 2000) and #231 (July 2000) of the french RCM magazine (8 pages in colours with pictures but...in French).
You will find also some articles in Electric Flight International magazine (April, 2000) and Model Airplane News.

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