Wednesday, December 3, 2014

RC Pilot, december issue

My review (in French) of the Vagabond from Hacker Model has been published in the december issue of RC-Pilot (

RC Soaring Digest, december issue

I forgot to relay the information that the december issue of RC Soaring Digest is available. It is very large with many articles and includes my report about the F3F worldchampionship in Donovaly and the review of the Vagabond from Hacker Model.

You can download this issue here:

Tuesday, December 2, 2014

Video: Fly in Iceland

Filmed with a quadricopter (TBS discovery pro) by Thibaud Ringenbach, who is also a F3F pilot. Behind this 5:40s, they are  41 flights corresponding to 7 hours in the air, "only" 85Gb of data and 4 month of editing.

The result is this hauntingly beautiful video !

Sunday, November 30, 2014

A world premiere ?

Thierry Monnot 3D printed the fuselage master of his new VTPR plane called the Minilimande. After many hours of printing, and a cost of 40 euros of material, Thierry obtained this multipart fuselage.

The approach is very innovative, for a super result. The rest of the work remains usual with sanding, gelcoat before to obtain a final master to be moulded.

You can find more pictures and information on his blog: The Breizh Maker

Thursday, November 27, 2014

Flying the Rotmilan Midi

Read also:
Part 1: Kit overview
Part 2: Assembly

After testing many many F3F sailplanes over the last 20 years, I can say that I can split them in 2 main families: the "Slippy" and the "Grippy". The Slippy includes planes having a fast natural speed, even with low ballast. The grippy are  planes providing lots of lift in the turn and that can carry lots of ballast, and most of the time need a minimum weight to fly fast. The Rotmilan is part of the Slippy family, that is to say using a section which is more naturaly fast.

In small condition, the Rotmilan is fine but cannot do tight turns with low lift. It starts to breath in medium condition and is an easy and well mannered plane. In stonger condition, it doesn't need too much ballast, and can manage the crossed wind good.  The Rotmilan is also doing excellent bank and yank turns, very aggressively, where some other place doesn't like it. Energy management turns or half roll half loop turn are also possible. The turn technique will of course give different result depending of the slope, the edge, the wind speed, etc ...

In medium to strong condition, as soon as it reach it's flight regime, the Rotmilan retains its energy very well, and can bank and yank hardly with an excellent exit speed. HN sections are know to be optimized without the extensive use of flap to change the camber. Therefore the amount of snapflap must be low otherwise the plane slow down in turn. I found a good compromise with a CoG at 106mm.

Compared to his larger brother the standard Rotmilan, the Rotmilan Midi is more agile and can be flown more aggressively. I also found that it turns better with a bit more grip, thanks to the equivalent tail for a shorter wingspan and shorter fuselage.

My Settings
  • CoG: 106 mm from the leading edge
  • Elevator: 6 mm Up / 6mm Down
  • Rudder: 10 mm Up / 10 mm Down
  • Ailerons (measured at the intersection between flaps and ailerons)
- Ailerons: 30 mm Up / 15mm Down
        - Flaps: 15 mm Up / 5mm Down
  • Snapflaps(measured at the intersection between flaps and ailerons)
- Ailerons: 6mm Down
        - Flaps: Aligned
  • Camber -  thermal position (measured at root)
- Flaps: 5 mm Down
- Ailerons: aligned
  •    Camber - speed position (measured at root)
        - Flaps: 1mm Up
- Ailerons: aligned
  • Butterfly  (measured at the intersection between flaps and ailerons)
- Ailerons: 10 mm Up
        - Flaps: 40mm Down
- Elevator compensation: 4mm down

To conclude, The Rotmilan Midi bring some improvements compared to the standard version, mainly agility at the ailerons and a bit more grip in turn. It remains a very affordable and still competitive F3F plane, with a superb moulding quality.

Hereafter are 2 videos I did in October and November:

Sunday, November 23, 2014

Breaking news: New DS world record at 813 km/h !!!

The 800 km/h barrier has been broken by Bruce Tebo flying his Kinetic 130 at Weldon (California) the 22th of November. After a first flight at 503 mph, Bruce improved it with 505 mph (813 km/h). For information, he doesn't use any gyro in his plane.

Saturday, November 22, 2014

Fresh air and some snow !

This afternoon, I went to col de Faisses again despite some snow falls the previous days. The ride to the top was a bit difficult because of the snow, even with a 4 wheels drive, certainly because of the summer tires. Temperature was cool, about 8 degrees, and conditions smooth, with around 6 to 8 m/s. I was alone adn had the entire slope for me :) !

I used the mobius action cam in photo mode, and timelapse to take to onboard picture with the cam attached at the wing tip. I also did some video with the mobius and also the GoPro on the ground.

Friday, November 21, 2014

Zepsus Magnetic BEC

Life, Lipo or more recent Li Ion receiver batteries are usually in 2S so deliver high voltage. However some servos released few years ago have not been designed to support high voltage and can at least reduce their lifetime when used with high voltage, or even can burn. Zepsus, well know for the magnetic switch that became very popular all around the world and equiping lots of F3X glider, recently released a new magnetic switch that includes a voltage regulator.

This Magnetic BEC features an impressive 14A max output current, operates with a 3 volts to 10 volts input voltage, is configurable to deliver 5, 5.5 or 6V output. It is compatible with all chemistry, from a 5S NiMh or NiCd to the more and more used 2S LiPo, LiFe, LiIon. The big advantage of the Lixx chemistry is that they can deliver higher current corresponding to the very demanding modern servos. The voltage regulation is linear, so what I would call RF friendly (ultra low RF noise) at the opposite of the usual U-BEC that can create problem with the receiver depending of the installation. 

Zepsus magnetic BEC is deliver in a small plastic bag with a small magnet and 2 stickers to install on the fuselage to indicate where to apply the magnet to switch on and off the magnetic BEC. It has a dimension of 59 x 26 x 5mm, and has a radiator face to dissipate the heat if needed.

The quality of the Zepsus Magnetic BEC is really nice with silicone JR type extension on the receiver side (2 times 0.5mm2 section). It has 2 connectors to provide some redundancy, but first to allow higher current. On the battery side, it is also large silicone wires (1 mm2 section). I installed a JST connector (crimped) to be compatible with the batteries I uses. On one side you have a jumper allowing to select the output voltage you want. When ON, a bright green LED allow to see the state of the switch. It is so bright that you can possibly see it through the nose cone. A small magnet is provided, but I recommend to use a bigger and stronger magnet like the Jeti magnet. It eases operation greatly from my point of view.

So if you have gliders with LV servos but you still want to migrate to HV batteries that provide higher capacity, low self discharge, higher max current, this Magnetic BEC is definitively the way to go. For small plane there is an smaller version of the magnetic switch delivering 5A, and with a single connection the receiver. I have 4 or 5 Zepsus switches in my competition planes that I uses for several years and I'm very statisfied by the quality and reliability of them. It is so convenient to close and tape the nosecone at the beginning of the day and switch on and off easily with the magnet that I couldn't return to a mechanical switch ! I definitively recommend Zepsus switches and this new magnetic BEC as Zepsus's owner (jesper Christensen) is also a F3F pilot and competitor so he knows what he is talking about !

Magnetic BEC Specifications

  • Input voltage range: 3~10V
  • Designed for 2s Lipo/Liion/LiFe or 5s NiMH/NiCD batteries
  • Output voltage choice: 5,0V/5,5V/6,0V
  • Output current continuously: 14A
  • Output current burst: >30A
  • Ultra low stand-by current: 6µA (micro-ampere)
  • Max power loss continuously: 8 Watt
  • Max power loss burst: >40 Watt
  • Ultra low dropout voltage: 63mV@8A
  • Connectors: JR-type “Double connector to receiver”
  • Wire: high-quality 1mm2 and 2×0.5mm2
  • Weight including cables: 14.5grams
  • Length including cables: 19cm
  • Dimensions including heat shrink: 59 x 26 x 5mm
  • Operational temperature range: -40C to +125C

Wednesday, November 12, 2014

[Movie] Interstellar

Seen on RCgroups:

The opening sequence of the movie INTERSTELLAR with an indian drone flying alone over the fields was done using a 33% scale Predatorish miniature, 5.5 meters wingspan, weight from 10kg, powered by  a Neu propulsion sytems. The group of south california soaring modelers composed of Larry Jolly, Ben Clerx, James Turner, Dennis Brandt, Dean McCoy, Chris Jolly, and Anya Ellis all pitched in, and helped get things done in time..

For information, Larry also participated to the movie Armagedon, and plenty of other nice project in Hollywood !

The full story can be read here

Interstellar is a super movie from Christopher Nolan, with a nice story (A group of explorers use a newly discovered wormhole to surpass the limitations on human space travel and conquer an interstellar endeavor.), excellent actors, superb visual effects. It lasts almost 3 hours, but the time passes very quickly. I really recommend it !

Tuesday, November 11, 2014

3D printed radio installation

Today, I could see a very nice radio installation in a Electro Alpina 4001. All the different part have been 3D printed. The servo tray use an inner honeycomb structure. the propulsion battery support can move to change the center of gravity. The orange box host the receiver and the power switch. I have no picture, but the servos covers were also 3D printed. All parts uses PLA material and are made on a printer having a volume of 20cm x 20cm by 15cm for the height. The result is very neat and clean as you can see on the pictures.