ASW-20: Maiden flight

We’re currently going through an unusually long period with northerly winds (“Bise”). This is great for slope soaring (all our favourite slopes are north-facing), but flying at our club’s airfield is not recommended. Our airfield is on the leeside of the mountain along lake Zürich. In the morning the flying is ok(-ish), but around noon usually the Bise starts pushing its way over the mountain, causing very turbulent conditions with evil downwinds. Flying is really hard then, no fun, and the risk of seriously damaging the plane is significant. Before the bise pushes through, conditions are also challenging, with often gusty and changing winds, often also from the South or South-West, which means landing with tailwinds. Sometimes we also have amazing thermals for a short while just before the Bise pushes through and makes flying impossible.

Nonetheless I decided to take the ASW-20 out to our club’s airfield for its maiden flight. At our airfield I can safely start the glider using the bungee and landing is way easier than on the slope – especially without having any recommended butterfly settings. I was hoping that going out early enough would allow me to get enough flights in to get the basic settings of the glider in order, so that I can then safely take it to the slope and to our club’s annual outing to Hahnenmoos starting on 17 June. After a thorough double-checking of all functions the first start went very well. No trimming was needed, the ASW-20 flies like on rails. Over five flights and landings I fine-tuned the down-elevator mix for the butterfly function, reduced the throw on the ailerons and mixed in a bit of down elevator for the motor function so that it goes up nice and straight with medium positive camber. Landings were tricky – the first landing went into the tall grass, due to a stiff tailwind and too much down-elevator mixed into the butterfly braking. After that was corrected landings were better, but challenging with increasing and very gusty tailwinds.

The plane is what I expected it to be. It is incredibly responsive to rudder and ailerons, needing very little thrown on both. It has a wide speed spectrum, from very slow with lots of camber, to nice and fast with negative camber – even with its low weight. All characteristics which are great for a plane to use on the slope.

I now hope to be fly it on the slope in the next few days.


ASW-20: Ready for maiden flight

The ASW-20 is ready for its maiden flight. As I got the plane with all servos and IDS installed, the work wasn’t that much, but still took me a day and a half. Especially installing the FES was a bit more work than planned. I took the recommended setup, which, unusual for me, requires the bulkhead to be placed all the way at the front of the fuselage (usually I have a few mm at the front to also insert a carbon roving there). Positioning the bulkhead also wasn’t easy, as the nose of the ASW is all but round and I didn’t manage to get the fuselage as perfectly round as usual. Also the 3-4 degrees downward angle of the motor actually looks very much up and the 40mm Spinner isn’t quite as nice as the 42mm Spinner I usually get. But it still looks more than fine.

There were also a few mishaps with the wiring. The pre-installed wiring for the elevator and rudder servos had a shortcut between the signal wire of both the elevator and the rudder, so that they couldn’t be operated independently. I redid all the wiring for the elevator and rudder. Also one of the wing servos wasn’t working, but fortunately just turned out to be plugged in wrongly in the wing – which was easy to resolve.

I did some decals based on a Swiss ASW-20 I found on the web – I may do something different if I find something nicer.

The plane is now 4.76kg, well below the planned weight of 5-5-5kg. Together with the powerful 6S leomotion outrunner setup that should make for very easy handstarts.

Here are the specs of the ASW-20:

– Wing Servos KST x10 and X08plus (ailerons)
– Elevator and Rudder Futaba 3174
– LeoFES L4632-340
– Freudenthaler Scale-CFK-Spinner 40/6.0mm/+0® mit Versatz
– LeoFES L46xx Spant 38mm aus CFK (probably a 40mm would have been better)
– Leomotion Carbon Propeller 18.0 x 13.0 Scale (8m m) – weiss
– ESC Castle Light 100

I’ll fly it with 2x 3S 3300mAh LiPos and a 2S 450mAh backup LiPo running over a Scorpion Powerguard. I also use two Futaba R7008SB receivers in an S.BUS Setup over a Dualsky S.Hub Duo. I’ve set the center of gravity at 85mm as recommended, but with space to move it further back.

New Project: ASW-20 (Mächler)

My new ASW-20 ist there!

One of the other pilots we frequently encounter on our favourite slope is Christoph Mächler. Many of the building techniques we use for our self-built planes originate from him. For the past year he’s been flying a really cool (and fast!) ASW-20 that impressed me very much. The plane is built for him in the Ukraine, using old fuselage moulds he bought a while ago, using new wing profiles and layout that he designed himself. The building techniques are still very similar to ours – the wings are foam core, but with plenty of carbon, glassed and spray painted. Unlike our builds, the rudder is a very light balsa ribs with oracover. The wing joiner is full carbon.

I’ve always like the design of the ASW-20 and am also always on the lookout for good slope planes that are performant but also light enough to hand-start on the slope. Last summer he offered to have one built for me. The plane arrived last week. The build quality is excellent – better than my self-built planes. It’s a bit heavier than how we would build it on account of having way more carbon in the wings, but that’s a good think as I want to use this plane as a slope racer.

Wingspan is 3.8-4.1m (different wingtips). Flying weight should be around 5-5.5kg. The plane came with KST servos and IDS (RDS for the rudder) fully installed. All I need to do is install the FES and bungee hook, finish the electronics, program my transmitter and it should be good to go. I hope to maiden this before we head off to our annual club flying week in Hahnenmoos on 17 June.