Maiden flights are nerve-wrecking. Always. We usually do them in aerotow, which is the safest option (during the tow it’s unlikely that something will happen and after release you have enough height (time) to correct something that’s wrong). As I did not put a towhook into the Ventus, the next-best option is to launch it using our bungee.

Before the maiden flight we always get a colleague to double check programming and settings – which more often than not finds a smaller or even bigger “issue”. The Ventus decided to “release” the propeller and spinner during the standard “full throttle test” – even though I checked and tightened it while preparing the plane in the morning. No other issues turned up during the check, so after reaffixing the prop and passing the “full throttle test” it was time to launch it.

The moment of truth is right after the plane releases from the bungee. This is when all the hours of work either turn into a success or – when you’re very unlucky – catastrophic failure. The Ventus was a great success. It flew off like it already had dozens of launches behind it. No trim needed, just perfect. Even better was that after a short burst of motor to get to 100m above ground (where usually the thermals on our airfield start) it flew straight into a thermal and started rapidly gaining altitude. My flying buddies, impressed with the launch, half-jokingly told me how cool it would be to have a one-hour first flight.

Their “prediction” was way off. After a full two-hour first flight, with a grand total of 25 seconds motor time, the pilot’s batteries were empty. I also wanted to make a number of minor changes in the programming (reduce elevator throw and add a bit of down elevator with the throttle) and check these in a second flight. The second flight also lasted a full hour and was ended only by my need to head back home.

The Ventus 2c is a really nice all-rounder. The handling very much feels like the JS3 – although of course not quite at the same level. The weight of 4.66kg is also just right. A floater, easy to hand-start and perfect for those light winter, spring and autums conditions.

The final bits (finishing wiring, determining the Center of Gravity, installing all the bits in the right place and programming the transmitter) are always a lot of work. But now it’s done and the Ventus is ready to maiden. I’m very happy with the final weight: 4.65kg, nicely under the 5kg target I set myself. With a 4.5m wingspan I expect it to be a real floater and easy to make hand starts.

I’ll be pretty busy with other things in the next week, but hope to maiden it as soon as possible. 🙂

While waiting for the silicon hinges to cure I started preparing the wiring for the wings. I also finished most of the work on the fuselage, installing the rudder and elevator as well as the bungee hook. Using my trusty Silhouette Cameo3 I cut the decals, pushing the Cameo at it’s limit on the tiny letters that will come under the canopy. In a burst of inspiration I also finished the seat pan for the cockpit.

Cutting the wing control surfaces out of perfectly finished wings takes some convincing, but especially a clear mind and a steady hand. It’s a job I only do when I feel that the time is right and I’m ready for it. But even with all the precautions I usually do make one or more small mistakes, but fortunately so far never bad enough to ruin the wings.

After carefully measuring out the location of the cuts and checking the small holes in the wings that I made during building (to help locate the right place for cutting out the control surfaces) I finally felt that it was time to have a go at cutting. To cut the wings I use an old Dremel that has a brass add-on to help guide it and ensure a straight cut. I cut it along an aluminium profile that I attach to the wing in the right place using double sided tape. On the top of the wing I use a 2mm milling bit, on the bottom (where the hinge comes) a 1mm milling bit.

Once the control surfaces are cut out and cleaned from excess foam I sand back and then glass the upper protruding bit on the side of the wing (50gr glass cloth with epoxy resin). This is to ensure that the seal (which I will make later) will slide nicely and tightly under the wing. I also cut out all the openings for the servos and servo levers. Then I attach the control surfaces to the wing using good quality wax tape (not TESA, but one bought at a professional paint supply shop) and set the hinge using silicon, applied with a syringe. It’s then reinforced with bits of ebechi on double sided tape to ensure that all the control surfaces are in the right place while the silicon is curing. The silicon hinges take approximately three to four days to fully cure.

This morning Andi delivered my Ventus 2c back from the paintshop, where he painted it yesterday. It looks awesome, once again an excellent job.

From experience I know that still 30-40% of the work needs to be done – mostly “small” and less visible jobs: polishing, cutting out control surfaces, setting hinges and seals and installing all servos and electronics. Hope to maiden it this year still.

I’ve not had the chance to keep updating the blog, so here’s an effort to catch up. Three weeks ago I finished the preparations to enable the Ventus 2c to be sent off to the paint shop. It’s been painted with filler and sanded again. Also the fuselage got a thin coat of filler on the seam (not visible on the pictures below). Unfortunately the paint shop has been very busy and I’m still waiting for a slot. I’m hoping to have it back in the next few weeks.

Canopies are nicest with a white band around them. Painting this is always a bit tricky. Some of my mates paint it by hand. I like to spray paint it. This is a bit more work, but in my view gives a slightly better result. I first sand the edge of the canopy that I intend to paint. Then comes the most important part: covering the bits that should not get paint on them. I first apply good wax/painters masking tape around the edge. This must be good quality tape – cheaper tapes (including the commonly available TESA) often result in the paint getting under (or through) the tape and ruining the canopy. Make sure this is well pressed onto the canopy. Then comes the job of covering all the rest. One small hole anywhere in the covering and the canopy is ruined – spray painting will always find this hole. So don’t save on tape and make sure all is carefully covered. After that I first apply a few coats of primer to make sure that any remaining small gaps on the edge are filled. Allow this to harden out and, if necessary, slightly sand to remove any uneven parts. I then use a standard car paint to spray paint the edge. Important is not to wait too long with removing the tape – I usually wait until the paint is ok to touch but hasn’t fully hardened out. Waiting longer may result in chipped edges (one of the reasons I paint the canopy myself at home, and not with the rest of the plane in the paintshop).

Before having the wings and tailplane spray painted, they first need a coat of primer to ensure an even surface and fill the structure of the glass covering and any pinholes in the glass covering. This is a terribly messy and smelly job, best done in a well-ventilated area on a not too cold/not too warm day. Not one of my favourite bits. I apply the primer using a metal “Japan Spachtel” (Japan or Surface spatula) and a paint brush. Note that this primer is extremely agressive and will dissolve plastic containers as well as normal paint rollers. I also use a good mask while applying it.

Cutting the canopy to size and glueing it onto the frame is one of those jobs that’s tricky and easy to get wrong. Worst of all is that any mistakes are very visible afterwards – a badly fitted canopy can really ruin a glider. No wonder I’ve never met anybody who actually likes doing this. Same here. I always wait for a day that “feels right”. I first check that the canopy frame is sanded to size (approx 1mm back from the outside of the fuselage – depending on the thickness of the canopy). Then I make the first rough cut of the canopy, place it over the frame (mounted onto the glider) and mark where I should cut it. Important is to make sure you mark the center at the front and rear of the canopy, to make sure that it’s always in the same place. The first “rough” cut I do using my Tamiya canopy scissors. Then it’s time for the (very rough) permagrit and 80grain sanding paper. Fit, sand, repeat (very often). I usually takes me 2-3 hours to get it right. Just be extremely careful with the sanding – one slip over the canopy and it’s ruined….

Once I have a fit that I’m satisfied with it’s time to glue the canopy to the frame. I do this using epoxy resin thickened with aerosil and micro-balloons. First I make sure that the fuselage is nicely waxed and protected with tape. Then I use a syringe to add glue all over the frame. Then comes the tricky part: carefully place the canopy over the frame and center the front and rear markings. Then I use wax tape to glue the frame in place. In areas where the frame is standing out I use leftover ebechi wood (vertical grain) with double-sided tape to make sure that the canopy is level with the fuselage. Now it’s time to let the resin cure and see how well I did this time.There will always be places where there was too much or too little epoxy, and I’ll need to make some small corrections after the first epoxy is cured.

The Ventus wing has multiple dihedrals. The first two were built into the wing as part of cutting the wing’s foam core. The last two (6 and 15 degrees) were too much for the thickness of the foam and must be added after the wing is completed. As it only concerns the outer two wing segments, there is no need for complicated spars or internal reinforcements. I simply separated the last two segments with a saw, sanded them back to get the right angle, removed some of the foam on both sides of the cut and re-attached the two segments using epoxy resin thickened with cotton flakes and aerosil. I did this in two steps, to make sure that I got the right and identical dihedrals on both wings. After letting the epoxy cure I will put a thin strip of 49gr glass fiber (45 degree fibers) over the seams, both on top and underneath the wings. That should be strong enough for this glider.

It’s always satisfying to see the wings of a new build for the first time “in full”. I spent two mornings with help of my flying buddy EP to close both wings – the first time I am doing this in my own workshop. I was a bit nervous about how accurate my calculations for the thickness of the main spar were (if you get it wrong then the carbon roving “overflow” from the cutouts, which is a pain to correct afterwards) – but they proved about right. I’m also not unhappy with the weight of the wings: 588 and 594gr. I’ll be able to reduce the slight difference in weight when sanding down the ebechi. The wings are around 40gr heavier than the ones built in my club twenty years ago (they came out at around 450gr). The reason for that is that all inserts in the wing are carbon rather than a combination of kevlar, glass and carbon in the earlier builds. The biggest difference is that I significantly beefed up the amount of carbon rovings in the main spar – the wing is nice and stiff – perfect for the slope  :-).

While searching the net for good pictures or examples of Ventus 2c instrument panels I was surprised by how little I found. Fortunately there was a nice drawing of an instrument panel among the papers from the first builds of the Ventus in our club 20 years ago. As this may be useful for others as well I’m posting it below. I’ve also found a good enough picture of an panel “in action” and used that to pick the instruments. I know the compass isn’t really in the right place….

After leaving the “raw” cockpit frame to cure for a few days it was ready to be sanded into shape (our epoxy cures in 12 hours, but it’s easier to sand if you leave it a few days). With a lot of material needing to be removed, this is a messy job, but the result is ok.

I also used a glass fiber plate that I made with two layers of 100gr glass to shape the cover of the instrument panel. The plywood panel is based on a drawing of the original cockpit panel. After potisioning this with 5 minute epoxy, I cut the individual glass segments. These I also glued in place with a few dots of 5minute epoxy and then added two layers of glass with epoxy resin on the inside.

My mate Georg gave me a really old seatpan from his stock that fits well with the fuselage.

The result isn’t totally “scale”, but good enough for me.