Slope testing the Chocofly JS3

After Friday’s maiden flight in aerotow, I could test the new Chocofly JS3 Rapture on the slope today. The conditions were perfect for the JS3, very light lift, with great intermittent thermals. We had three JS3 on the slope, one scratch-built by Georg Staub, identical to my scratch-built, with around 6.3kg, one scratch-built by Richie Oberholzer, without FES, around 5.5 kg, and my Chocofly with JETEC E-70 with around 6.6kg. We were all flying the 18m/5.14m version (I only have this version for my Chocofly JS3, and always fly the longer wing version with my scratch-built).

The Chocofly version is virtually identical to our scratch-built JS3. The differences are of course that the wings are fully moulded, whereas our own are foam core with carbon/glass layup. The elevator of the Chocofly JS3 is approximately 1cm less deep, and the fuselage approximately 2cm thinner. In addition the wings have 3 rather than 4 control surfaces.

With the identical wing and elevator profile, the performance of both planes is however very similar. We did some formation flying in different camber settings. My JS3 and that of Georg performed equally well, with the Chocofly version giving the impression of being slightly more performant in thermals. With more robust wings, the upper end of the speed spectrum is of course also higher for the Chocofly version – I got to 230kmh in some of the low passes.

The JS3 (both my scratch-built and the Chocofly version) ist the best scale glider I have for flying in thermals. It picks up the least bit of lift and allows for slow, tight turns, very similar to a F5J glider. With the multiple dihedrals in the wings, it turns mostly on rudder and only needs minimal aileron. Even with massive camber settings it is hard to stall, and it announces a stall very nicely – nasty stalls are very rare. The nice things about the Chocofly version is that the 5.14m also allows for higher speed passes, and of course having a JETEC rather than FES makes the plane so much nicer to look at.

To note is that there is also a 4.28m version of the JS3. I have shorter outer wings for my scratch-built JS3, but, to my shame, have never flown it with these. I may however be tempted to order the shorter outer wings for the Chocofly version. With the shorter outer wings it should be quite the slope racer – although in the GPS version not as much as my Apline Edition Diana2 (with which I can do just anything). To be decided.

I’m still not done with determining center of gravity and longitudinal dihedral. I did move the CG somewhat backwards but have found that I still need quite a bit of uptrim on the elevator. I hope to get some test flights on one of our local airfields soon to sort this out. I also still need to sort out the battery issue. I’ve using 2 older 3S 3700 LiPos as a 6S setup, with 4mm plugs, which I’m not happy with. I’ll be measuring Ampere/Watt of the JETEC shortly to see what power flows, and will probably adjust plugs and battery. I’ll also replace my 2S LiPo that I use as a backup power source (next to the BEC). More on all that later.

Even with all this, the plane flies great already, it will only get better. I’m a big JS3 fan, together with the 1:3.5 Diana2 it’s my favourite plane.


A day at the races – EMB400 Urupema in awesome slope conditions

Finally, spring weather! And added to that a stiff northern breese (“Bise”), means time to head out to the slope. Yesterday’s conditions were almost scary – a stiff and gusty wind, and very turbulent conditions. We decided to take our Urupemas, which were built for precisely such conditions, although the turbulent conditions pushed them to their limits. The tall grass unfortunately meant that a catapult launch is difficult and a dangerous hand-start was necessary – fortunately this went ok, although two starts were close to going wrong (planes over 6kg on a slope without a drop and gusty winds is challenging). Below a short video of yesterday’s flying.


Slope season start!

As the snow starts to clear from nearby mountains and temperatures are slowly going up, we had a couple of days of great wind for our favourite slopes. Most nearby slopes are good to fly when we have a northern breeze (“Bise”). About a 10 minutes drive from where I live is the Pfannenstiel Hochwacht. It’s not the best of slopes, but a good place to head out to when the weather is too cold to make longer flights or when you just want to head out for an hour or so.

In mid-April we had three good consecutive days of Bise, but still very cold and cloudy weather, and most of my usual flying buddies didn’t feel like heading out in the freezing cold. I spent three lovely but freezing cold afternoons up on the Pfannenstiel with my Chocofly 2.8m Taranis and my Chocofly 2.2m Kobuz, accompanied by a few friends. The Kobuz is a lot of fun to fly, you notice it’s smaller size and the fact that it’s not a purpose designed aircraft – it’s “lively” and requires you to work the sticks :-). The Taranis is a completely different plane. It’s got a huge speed envelope, is pretty hard to stall and totally stable to fly even in the most turbulent and windy conditions. Lots of fun – including some high speed passes at over 310 kmh (without ballast in the lightest version of the plane!).

Last week the weather got a bit warmer and sunnier and with another few days of Bise we were able to head out to our favourite (private) slope in Toggenburg. We opened the slope season there with our Diana 2, the 4.28m version (both scratch-built and the Chocofly version of the same plane), and on the 2nd day we took out the 5m Diana2. My mate Richie also “slope-maidened” his brand-new EB29R – with an incredible 8.3m wingspan and only around 9kgs. I got some time on the sticks of the EB29R – an amazing thermaller. See the video I did on the first slope flight below.