Showing posts from 2017

RC Soaring Digest December issue

December issue of RC soaring Digest is available with plenty of interresting articles. Just follow the link below !

RCSD December issue.

Large Scale Glider meeting of St Jean en Royans

Mid october, I stopped few minutes at the GRP meeting of Saint Jean en Royans. Lots of very nice sailplanes, tow planes. Weather was perfect with plenty of thermals, with vultures, no wind. The airfield of Saint Jean en Royans is superb for this type of meeting. Below my photo album. 
Video of my Excel 4004 I built in September and flown few time. More to come.

[Essai] Weasel TREK de Dream-Flight, l'aile volante ultime ?

Introduction  Après une très longue attente suite à l'arrêt soudain de la fabrication de la Weasel EVO, essayée dans ces colonnes en 2009, la version revisitée est arrivée finalement début 2016. J'étais très excité d'essayer cette nouvelle Weasel TREK car j'avais vraiment craqué sur la première version. J'ai d'abord eu la Weasel EVO, puis plus récemment une Weasel Black Édition, ce qui me permettra de comparer. Et puis si les améliorations sont du même niveau que pour l'Alula TREK, alors cela promet ! C'est parti pour un essai de cette nouvelle  aile "Made in Californie" ! Aperçu du Kit  La Weasel TREK arrive dans un joli carton rectangulaire qui s'avère bien plus pratique pour ranger et transporter l'aile. La forme de la Weasel ne change pas beaucoup et reste certes moins élégante que l'Alula, plus massive, certaines mauvaises langues diront une esthétique de fer à repasser, mais si vous vous arrêtez là, alors vous passez à côté …

Digitech Angle & Throw Meter

I continue my migration to digital tools !  I just received my Angle &Throw meter from digitech in Netherland, and designed by Daniel Maiorano. This device allows to mesure angle and travel in mm, as you can enter the chord of the surface, very smart !  It comes without user manual or mount. After thinking a bit, I finally just double taped a epoxy plate behind the case, and which stay on it, then I paper tape it. the case is 3D printed, and it features a small OLED screen, very crisp and with excellent contrast.
The use is very intuitive. First you fix it on the surface, then you power on with a 4.8 to 14V battery. Before to start calibration, you need to set the chord, by clicking on the +  or -. When ready you click on the "F" button, there is a 3 seconds countdown before to enter calibration and set the Zero position.  You can start measuring ! Overall, this is a nice device that allow to replicate settings with precision, I just regret that the chord has to be re-e…

Flying session in fresh air !

Some fresh air and a nice flying session near Grenoble. No F3F as the slope was not suitable for it, but few nice aerobatics and overall relaxing flights in a beautiful scenery.

The photo album can be seen here


Small visit to a local aeromodelling field where club members were doing towing in this nice and cool afternoon with a temperature around 13°. The opportunity to see nice flying machines up to 8 meters.

The photo album can be seen here: Photo Album

[Hints and Tips] Wiper dents and missing parts repair

I found this epoxy sealant from UHU at Lidl for a very low price and it appears to be perfect to repair damages of wipers on the wings.

It looks like gray modeling clay. You mix it during few seconds before to apply it. then it cures in 10 minutes. It can be drilled, sanded, painted. Really convenient and with a very good result.
Approved :) !

[HOW TO] Calculate the CoG from the weight

Given the number of questions I still receive :) , I see that the concept of measuring the CoG location by measuring the weight at the leading edge and X mm behind is not fully understood, so let's explain again with a real case, my Stribog CoG:

2 kitchen scales measure the weight of the plane, separated in my case by 293 mm. The first scale measure the weight at the vertical of the leading edge, the second one 293mm behind, so behind the trailing edge.
The sum of the 2 weight measured give the weight of the model. Now we apply the formula of a barycenter of a barrel that says: a x p = b x p'.

In other words, the if I measure p and p' , and also that I know the distance a+b (293mm in my case), so that b = 293 - a, I can easily calculate the CoG location.
So now, let's do it for real. My Stribog is placed on the device: I measure 1475gr at the leading edge, and 834gr at 293mm of the leadging edge. After entering the formula in Excel, it gives me a CoG located at 105.83…

CoG Machine

I finally found the time last week-end to assemble my CoG Machine, made from 2 kitchen scales, some aluminium and 3D printed parts. The 2 scales are glued on a wood place using some cartridge sealant. Prior to that, I did a trapdoor below to access the batteries. The 3D printed support is also sealed on the scale plates so everything is fixed together.

Just as a reminder, as lots of people asked me how it works, just look at the drawing ont he right and extrapolate to obtain the formula giving the location of the CoG from the leading edge, knowing waht the scale measure at the vertical of the leading edge and what the second scale measure X cm behind.
The advantage of this method compared to the usual CG balance is the repeatability of the measure.

I know that, since my first post on Facebook, some CoG machines are in construction here and there ;) ! This is good to know !

Some very interresting new products from

Image has been the first company to introduce on the market servo frames years ago, covering almost all model of wings servo, but not only.
It is nice to see that they are following the LDS trend and adapting their products to customer needs.  Here are few new products I received from Florian:

- MKS HV6130 servo IDS frame: The pocket includes a new specialized frame for the recent and great servo HV6130 from MKS. The frame features an external counter bearing, and 2 fixing position. I noticed that this frame can host the HBL6625mini or the DS6125mini. The frame is provided with a set of 4 servo head, with different axis distance covering the various needs (ailerons, flaps, etc ...). Then a very interresting set of plastic arms with different length from 48mm to 81mm so you can solve easily any installation whatever the position of the servo from the control surface. The material used for the control arms includes carbon (Carbon fiber reinforced polymer), so are very rigid.
- …

First flight of 2017 !

I finally exited from hibernation and had did my first flight of 2017. Past weeks were very cold with no wind so it was nearly impossible to fly. This time, on a slope near my home place, I had good weather, some south wind and 10°.

I flew my Stribog with 900gr of ballast. After 3 months without touching gimbal sticks, I'm happy to see that I still know how to pilot. Finally it is like bike, once learned you never forget :) ! This afternoon, I though also I could see the "death star" , but it was only the moon ;)

[HOW TO] Hinge repair

Before the 2017 season starts, my prefer neon orange Shinto which survived to col de Tende radio issue, and which allowed me to reach the 3rd place at the last world championship needed some maintenance and attention as the wing that has been repaired (partially delaminated, hine partially cut) showed again some degradation on the hinge during the last league contest at the point I needed in urgence before my last flight to apply some tape to secure the flap and avoid more damages of the flap wiper.
I used the same technic that I will explain now. First, I apply some thin transparent tape to well align the flap with the wing with no slop. Second, I disconnect the lds head to get more rotation and free movement. I protect the 2 side (wing and wiper) with some paper tape.
I use sikaflex 11 FC which is a mono component advanced polyurethane, elastomeric sealant/adhesive, exist in different colors. This time I choose black as the Shinto underside color is also black. (http://…

Essai du Vagabond XL de Hacker Model

Vagabond XL de  Hacker Model Plus grand … mais plus performant ? Texte : Pierre Rondel, Photo : Joël Marin et Pierre Rondel
Un an après la sortie et le succès du Vagabond, un planeur de VTPR en EPP,  Hacker Model a décidé de sortir une version revisitée et plus grande baptisée XL, avec une envergure de 2m au lieu de 1.50 m. Quand j’ai vu l’annonce, je me suis d’abord posé la question de l’intérêt d’une telle augmentation d’envergure et si le Vagabond n’allait pas perdre en agilité. C’est ce que je vous propose de découvrir dans cet essai. En quoi est-il diffèrent ? Outre l’envergure,  la longueur de fuselage est identique. Si l’on dispose côte à côte les 2 fuselages, on s’aperçoit que le fuselage du XL est plus haut et offre plus de surface latérale. La dérive est aussi plus grande. Le servo de profondeur a été déplacé à l’arrière, juste à quelques centimètres du stab. C’est une petite déception car les premières photos et description laissaient entrevoir l’utilisation d…