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 mobisu 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.

Monday, November 10, 2014

2 new color schemes for the Vagabond

2 new color schemes for the Vagabond from Hacker Model. The honeycomb is very popular now ;) !

VV Stinger

While the Stinger 2 is about to be released soon, here are pictures about the kit of the Stinger. This one is not belonging to me, but stayed at home for few days before to be delivered to his happy owner.

Col de Faisses

Some pictures taken at col de Faisses the 1st of november. My F3F planes stayed in the car and I flew only my Weasel Black Edition. Other planes were mostly powered as the conditions were very light. Still a nice and cool afternoon with a super light for pictures.

2 weeks before, I had another session there where I could meet some pilots from Lyon area. Conditions were much better.

Aerial pictures: Castle of Bon Repos

While some stupid people are flying with drones over french nuclear power plants, there are many better things to do with a quadricopter like photographying the Castle of Bon Repos near Grenoble. The Quad is aTBS discovery and the cam is the GoPro3 black edition in timelapse mode. From the 580 pictures taken, I selected only 33 to create this photo album.

Zepsus Magnetic BEC

Zepsus just released a new product called "Magnetic BEC", which combines a magnetic Switch and a 5-6V linear voltage regulator. It allows to power a F3x glider equiped with Low Voltage servos from a 2S Life/Lipo/LiIon battery. It is available in 2 versions: 14A for F3x plane and 5A for HLG gliders. Given the excellent quality of Zepsus products (I have 5 Zepsus magnetic switches in my F3F planes), there is no doubt that this new Magnetic BEC will be a best seller !

More info at

Wednesday, November 5, 2014

Rotmilan Midi Assembly

Note: you can read the first part here: kit overview

The rotmilan doesn't reserve any real surpise during the assembly. There are however some particular points to to take care so I will develop. On the fuselage, the most delicate operation is the wire routing from the front of the fuselage to the green plug print location. Because of the bassat tube already in place, there is very little remaininf space on each side to route the 4 wires. They must be under the ballast tube, then go on the side to reach the wing plug hole. Here is the technic I used. I prepared the servo wires, around 45 cm long (the standard 30cm servo wires is too short). then using a thin piano wire (0.8mm) or a thin plastic sleeve, I passed it from the joiner location to the fron of the fuselage, then taped the wire extremity to it, and pull carefully until the wire exits. You need to do it 4 times (2 on each side), given that the second wire has even less space since the firt one is in place. Doing like this, it is not painful, but still requires some patience. The plug holes doesn't have recess to block the plug in place. I created it by gluing a 1mm plywood piece going from one plug print to the other, top and bottom. Once done, yuou can exit the wires, sloder them on the green plug, protect the soldering with hot gun glue and glue them in place with rapid epoxy.
On the rear side of the fuselage,

I used MPjet brass threaded coupler. There were with a 1.3mm, so I drilled to 1.5mm. The linkage provided has a layer of teflon that you need to remove first. The core of the linkage is fiberglass. I glued the coupler on it with some rapid epoxy, and crimped twice (at 90°) to secure it totally. To finish I glued the metal clevise on it to suppress any slop. The rear end of the linkage being done, I connect them to the tailplanes. I neede to sand the inner side of the fuselage to gain some space and allow the clevise to move freely. I also cut the recess that receive the end cap, and milled the end cap to allow the elevator horns to move. The result is very clean, simple and nice. No slope, free moving nice fit and junction of the parts together. This is obviously well designed and moulded.

Let's continue with the elevator servos. The tray is designed to receive 12mm servos like the MKS 6125e or equivalent. The hole is at the right size to not damage the wire when inserting the servos in its location. Here again, I used brass MPjet coupler after cutting the linkage at the right length. I then installed plastic MPjet (with metal axis) on them to have a tight mounting without any slop.

We can then start the wing servos installation. I used 2 MKS 6125 mini at the ailerons, and 2 MKS 6125 glider at the flap. As I said in the overview, the LDS is factory installed on the control surface, and is removable which is clearly a plus for any maintenance, or for the installation. for this a tool is provided. This is a long brass rod with a threated hole at one extremity. The LDS axis hae also a threated end. From the root of the wing, it is easy to screw the axis, then pull to extract it or push to install it. This is really well designed !

The linkages are epoxy board arms, the short ones being for the ailerons, and the long arms for the flaps.
On the servos side, after putting 2 extra layers of 93g/dm2 carbon fabric to avoid any deformation of the skin once the servo is installed, I sanded the surface, glued in place the wood servo frame. Make the operation carefully as the likage, LDS, servo head is mounted tighly and that any deviation will create friction or blocking point, so the servos will not work properly and the return to the neutral position won't be accurate. There are 2 servo head types: one with the hole at 5mm from the center which is for the ailerons, and one at 6mm which is for the flaps.

Once in place, I added a S-BEC in front of each servo as I use 2S LiIon battery, so high voltage. The wire extension done, I glue the green plug in the wing with the wing mounted and connected to the fuselage, and using some PVA release agent everywhere it is needed, in addition to some thin tape to protect the fuselage or the root of the wing. The flat servos covers are finally cut a the right dimension (there is a thin line to indicate where to cut) and taped in place.

Let's finish with the battery installation, and balance lead melting. As I said, the battery is a 2S LiIOn 18650 cell format, providing 2900 mAh. Once in place, the receiver takes place on top, with some plastic sleeve to guide the antennas. I needed 150g of lead to do the balance for a CoG at 106mm.

Finished component weight are the following:

  •     Left wing: 692gr
  •     Right Wing: 690gr
  •     Fuselage: 742gr
  •     Wing Joiner: 88g
  •     Left tail+ joiner: 40g
  •     Right tail + joiner: 42g

    Total 2294gr