dlg – Fly Sherlock Air

Flying the Libelle DLG on a slope

Ever since I received my Libelle, I’ve only been flying discus-launch on flat land in calm wind, but last night I saw the forecast for today was for a nice 10km/hr westerly wind and clear sunny skies. I had a hunt around on Google maps and finally found a west-facing slope. It’s a big hillside with a series of switchbacks and jumps carved into it as part of a downhill BMX race course, in Dunedin, New Zealand.

And indeed, when I got there a 10-20km/hr wind was blowing almost directly up the slope to me. I gave the Libelle a lazy javelin toss and wow! It zoomed straight up into the air. Suddenly, compared to flat-land, I had almost infinite power available. I even managed an aileron roll, although it seemed to hesitate forever at the halfway point. I quickly learned the importance of always making your turn into the wind instead of back towards the slope, as it wipes off a ton of airspeed/altitude if you do it the wrong way. Luckily not enough to make me crash.

Eventually I managed to lose enough altitude that I had to land it, about halfway down the slope. Unfortunately the slope is lined with 2 metre tall toetoe bushes, so visibility was extremely limited and I couldn’t see the landing spot. I had to hunt through gorse bushes in order to find it again. Once I got within 10 metres of it I was able to waggle the ailerons and immediately hear the servos whirring further down the bank. Nice gentle landing in grass:

I gave the control surfaces a quick check and then it was back in the air!

Unfortunately, 15 minutes after that first sunny photo was taken, a dark raincloud started rolling up the valley and it started to rain on me. I was going to brave it out, but my lift started dropping. I couldn’t manage to land it somewhere nice where I could guarantee I wasn’t going to get gouged by gorse again, so I decided to land it on that playing field you can see way the heck at the bottom of the hillside. (maybe 125m vertical).

Wow, depth perception is difficult at that distance! I set flaperons for landing, and I was like “Okayyyy…. touchdown! No? Tttt…….ouchdown! No?? What?”. Finally I made a perfect landing (pretty much by chance). It’s the tiny white speck you can see on the field through the rain:

Unfortunately the field turned out to be composed of 95% moss, it was basically a sodden swamp. My shoes have seen better days. Can’t wait to go back!

Libelle back in the air!

So, I previously wrecked my Libelle pretty hard, tearing both the wings and the nose cone in half. I’ve now repaired both of those using Gorilla Glue, which worked excellently. The glue foams up, so there is still some excess here and there that I haven’t sanded off yet.

I’m happy to say that it’s now back in the air!

I’ve been flying it until the battery runs flat for the past three days, and having a blast. My discus technique is slowly improving, though I’m still doing poorly compared to those I see on YouTube. I might take a video one day and get your guys’ suggestions. I haven’t found a thermal at my flying field yet, I might start hunting further abroad.

I’m now running proper flaperon mixes on my Taranis to give me Thermal and Landing modes according to the deflections specified in the excellent included manual, so my landings can now be much more gentle.

I noticed that since I re-glued the wings, their angle is offset compared to the tailplane, which obviously is not a good thing. One of the plastic mounts snapped in half when the wing did, so there’s not as much holding them in alignment any more. For the moment, I’m just going with the flow and flying counter-clockwise circuits to match the craft’s bias.

I managed to lose the carbon fibre launch peg, so I replaced it with a section of cheap paintbrush handle, which happened to be tapered so I could find a precise fit from halfway down the brush :).

RIP my Libelle DLG

RIP my Libelle discus-launched glider:

Memories of happier times:

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As to how that happened, it was due to repeated stupidity on my part. One day I had a crash where the battery popped out of its hot glue mount. I decided to just stuff it back in and continue flying, since “it’ll only take high shock during crashes and I don’t mind having to put it back in after a crash”.

You probably already see the problem with that: it’ll also experience high forces during takeoff. And sure enough, 5 or so flights later when I launched it, the Libelle went in one direction and the battery went in another. It doesn’t fly so well with no control and no nose weight, so after doing some wicked acrobatics it crashed into the ground nose-first, snapping the skid plate clean in half. But that’s not the end of the story.

I had re-glued the skid plate, glued the battery down nice and good, and got another 20 flights out of it before one aileron servo stripped a gear (not sure why, as I thought that the ailerons were the least molested of my control surfaces, unlike say the rudder). But that was okay because I was able to limit the range of travel of that servo (to about -50% to +50%) to avoid the stripped area. That was fine for a while, but a later crash killed the other aileron servo.

So this morning a box of new servos arrived from Dreamflight, and I replaced both stripped aileron servos. I got about 5 beautiful flights out of it before a slight crash caused the nose to snap off along the line it was already broken on. Now you’d think that this time I would have learned about G-forces from the battery incident, but no. I didn’t want to have to go home to fix it properly, so I just taped that nose cone back on. And exactly what you think would happen happened: The nose came off on takeoff, left me with an uncontrollable fall, and the wings and nose tore apart when it crashed.