A while ago somebody sent me a link to a really cool 70’s cigarette commercial featuring the Urupema. Somehow I forgot to include a link on my blog. Now corrected. Note: there is a brief shot of what seems to be the cockpit interior of the Urupema. Unfortunately that’s a fake, it’s actually a shot from the cockpit of a Blanik. Do turn on the sound for this video – it’s so seventies!

Link to the video on Facebook here

I regularly get contacted with questions or suggestions in relation to our builds. I was particularly happy by an email I got from Marvin S., who is planning to build a Urupema with his father-in-law and has done extensive research into this unique Brazilian glider. Marvin shared some really nice pictures that I hadn’t seen before, including one of the instrument panel (which we were unable to find for our build). Marvin kindly allowed me to share these pictures on my blog. I hope that they can be of use to other builders. Thanks!

I’m not usually one for great detail on my cockpits, but I wasn’t too happy about the orange cockpit seat and the square headrest of my Urupema. Also, some of the paint on the seatpan started to chip off. So I was very grateful when our building team colleague Richi offered me a beatifully made yellow seat inlay for my Urupema cockpit. Before sticking it onto the seatpan with hot glue, I also resprayed the seatpan, which now looks like new, and redid the headrest (now round). A great upgrade for an awesome plane methinks. 🙂

For the first time we got our four Urupema’s together! The regional model aircraft association (Modellflug NOS), organised an exhibition of scale model aircraft in the FLAB Aircraft Museum in nearby Dübendorf. Part of the exhibition had scale aircraft positioned next to their originals (very impressive!). In addition, the exhibition showed the results of the work of model aircraft builders during corona times. We were invited to show our four Urupemas. Quite a sight, and we’re proud of the positive feedback we had from visitors!

Georg has been busy fine-tuning the settings of his Urupema in Aerotow. The CG has been moved back quite a bit, and he has reduced the decalage back to around 0.8 degrees. The result is a much gentler plane, with excellent stalling behaviour, and an even wider speed envelope.

Last week Wednesday I got the first chance to fly my Urupema on one of our local slopes. Before heading out I applied the new settings to my plane. Wow, what a difference. Georg and I spent four hours non-stop airborne with our Urupemas. Even in light lift, the plane was a pleasure to fly. During the flight I swapped transmitters with my mate Richie, who was flying his JS3, just to see the difference between the planes and let him have a first taste of the Urupema (he’s about to finish his, nr. 4). They are definitely two very different planes, both much fun to fly. Of course the Urupema is not a thermalling junky like the JS3 (which just refuses to come down), but the Urupema still flies incredibly well even in light lift. After Richie landed his JS3 I handed him the controls to my Urupema again and asked him and Georg to do some formation flying, so I could do some filming (Richie is a much better pilot and I’m a much better cameraman :-). The result is below. Enjoy.

Today I maidened my Urupema on our club’s airfield, using the club’s catapult. I usually prefer to maiden planes in aerotow, much lower risk, but as thanks to Corona this is currently not possible. It was either catapult or wait. Since I plan to spend a week in Soaring Dreamland Hahnenmoos in a bit over a week, waiting was not an option.

The start went well, but the conditions were terribly turbulent, with massive downwinds and rare but strong upwinds. The landing was adventureous, with a terrible down and tailwind, and too much downrudder mixed into the crow programming, causing the plane to come in very fast on our small airstrip. Fortunately all went well, and the second flight went much better already, and Georg and I even managed to do some formation flying.

We’re still finetuning the settings on this lady, but she’s special. The speed envelope is amazing. You can circle in thermals at close to 40kmh, but she very quickly picks up speed. Without pushing it, Georg already had well over 260kmh. She needs a lot of rudder when circling in thermals, and really likes leaning into the curve. And it’s very hard to stall her, when circling in thermals you can pull the elevator like crazy. I’m only just getting to know her, but this is one special amazing plane. Happy.

This has been an amazing spring of contrasts. While Switzerland has been in a “soft” lock-down, we’ve been enjoying perfect weather and, most importantly, a highly unusual amount of so-called “Bise” days. Normally the prevailing wind is West. But the last few weeks we’ve mostly seen Northerly winds, the “Bise”. This means that it’s impossible to fly on our airfield (which was closed for a few weeks anyway), but also means time for slope soaring. I’ve spent many hours flying on our favourite slopes so far this spring. Pure bliss, although coming down from the mountain back into Corona reality was sometimes something of a shock. Below are some pictures, as well as a video that I did of the first slope testing of Georg’s Urupema. I’m still waiting for a normal westerly wind so I can maiden mine on our airfield – maybe the end of the coming week….

The final “small” things always take much more time than planned, but the Urupema is ready for its maiden flight! I still intend to add some red stripes and more decals. For that we will need access to the paint shop though, which is not easy due to the COVID-19 semi-Lockdown here in Switzerland. They will need to wait.

The plane weights around 7.2 kg (4.28m wingspan, scale 1:3.5). I can add quite a bit of ballast (up to a 800gr brass) in the ballast chambers built into the wings. Am curious to see how this one will fly. Unfortunately the maiden flight will have to wait a bit. I first intend to maiden my JS3, which has been sitting ready to maiden in the workshop since November last year. Then I want to wait for our building team colleague Georg to maiden his Urupema. Not only is he a master in getting the plane’s settings right, he also has access to an airfield where he can maiden his Urupema in aerotow (the safer option for a fully new own design plane), whereas I don’t (due to attendance restrictions for guests on most nearby airfields as a result from COVID-19).

I’m not very good in making nice cockpits. Although I admire colleagues that do perfect scale cockpits, I just can’t be bothered to take the time to do it myself and usually do a very rudimentary job. I’m too keen to get onto the next project or go flying :-). The Urupema cockpit was a bit of an issue, since we had no pictures whatsoever of what the original looks like. While Richie made a all of us very nice seat pans, we re-used the instrument panel from our Diana2, which looks to fit quite nicely. I also lack the skills to make a nice seat, so I usually just cut a piece of felt to size.

As our Urupema is built for higher speeds than usual, having a robust elevator is important. Usually we attach our elevators with plastic screws (allowing them to break with rough landings on the slope), but this time we attach it with a metal screw, but the front of the elevator is attached with a carbon rod (allowing it to break there if the elevator gets caught in a rough landing). The control horn is glass fiber. As the elevator hinge is on the topside of the elevator, the lower side doesn’t need an epoxy seal, I just use tape.

Earlier this week I also got the Urupema fuselage back from the paint shop. I spent quite a few hours sanding and polishing it to a shine. I first used 600 grain sanding paper, then 800, then 1500 and then a 3000 diamond polishing pad. After that I treated it with machine polish and shiner, using the polishing machine.

The paint shop and especially the polishing afterwards is always very unforgiving when it comes to small mistakes in the building. There are the inevitable spots where it’s not quite perfect, it’s obviously made by hand, but I’m satisfied. I’m particularly happy with the spray filler that I’ve used for the first time on the seam on the top of the fuselage and part of the wings. I was a bit nervous trying this out, hoping that it wouldn’t react with the final coat of paint. It came out well though. I couldn’t resist sticking a few of the decals on and putting the plane together for a photo session.

Now the hard work on finishing the wings starts. Next step is cutting out the control surfaces. No mistakes allowed there…

The filler/primer on the wings was sanded down again, to get a really smooth surface. Last week we also got the canopies, which we had produced by a friend, using our mould. I spent quite a bit of time fitting it to the canopy frame, before fixing it with epoxy resin. It looks quite good. I also fitted the towhook and bungee hook, as well as an extra bulkhead to hold the seat inlay. Today I prepared all the parts for spray painting (canopy is always a lot of work to prepare), as well as the tools to hold the parts during spraying and letting the paint harden out. Tomorrow I’ll bring all of it to Andi, the master painter in our building team. I hope he can get a slot in the paintshop over the weekend. I am very curious to see how it will come out…spray painting tends to be quite merciless in showing where you made mistakes……

The 49gr glass covering wings and elevator hardened out nicely, and I couldn’t help putting the plane together to see how it looks, now also with the landing gear :-).

Today I sanded the wings and elevator and cleaned them. After that I applied the primer/filler. First with a roller and then pulling it deep into the (few) pinholes using a spatula. I hate this part, as the primer stinks like hell. While it needs around 20deg C to harden out I cannot apply it outside, so I spent the morning in the workshop using a face mask. Now the primer can harden out over the weekend. On Monday it’s sanding time again….

Fitting the landing gear required fiddling a bit with the correct position of the two spants to ensure that the center of the wheel is 2cm behind leading edge of the wing. Then cutting the hole at the bottom of the fuselage to the right size so that the wheel fits through. The suspension is a couple of rings of inner bike tube, which we also use for our retract able gears. I always first provisionally fix the spants with a few dots of 5minute epoxy, and once everything is in the right place I fix it using 12hr epoxy.

Fitting the wheel casing is done with two 4mm screws. I first cut some plywood to size, fixed it in the right position on the fuselage with a few dots of 5min epoxy resin, then drilled the holes, removed the plywood from the fuselage and fixed it to the wheel casing. Using a syringe and some coloured 12hr epoxy resin I filled the small gap between the wheel casing and the fuselage to ensure a perfect fit.