Diana 4 and Ventus 2c: tail sections

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Earlier this week I picked up the rudder for the Diana 4. Fellow builder Georg built three of these for us, using the mould he made for the JS3 rudder. As usual it’s very nicely done and extremely light.

The tail sections of both the Diana 4 and the Ventus 2c are now as good as ready (of course the horizontal stabilisers and the Ventus rudder still need covering and painting):

  • 45 degree angle reinforcement to avoid torsion in the vertical stabiliser (3mm balsa, covered with 49gr glass on both sides);
  • vertical reinforcement to close the vertical stabiliser before the rudder
  • rudders fitted and brass tubes (pull-pull system with kevlar wire) fitted
  • elevator servo installed, including wiring

The pictures of the (transparent) tail section of the Ventus show best what’s where. We always prepare a sheet of 3mm balsa wood with 49gr glass on one side (glass applied in a 45 degree angle). The balsa wood reinforcements are then glued in with thickened epoxy resin and 49gr glass (also in a 45 degree angle). With the Ventus I also applied two thin carbon rovings – that’s because I felt like it and had it lying around, but it isn’t really needed ;-). Together, the two reinforcements give enough stability/torsional stiffness to the vertical stabiliser.

Ventus 2c: installing the motor bulkhead

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The Ventus 2c will get a powerful inrunner motor. This allows for a lighter motor with lots of power to enable easy handstarts on the slope. Urs Leodolter at Leomotion.com as usual helped me pick a really nice setup. With 6kg pull it should allow the Ventus to go near-vertical.

Installing the bulkhead was done using the usual technique. Once put into place using a few dots of 5min epoxy I fixed it permanently using 12hr epoxy and two small carbon rovings. See the more elaborate description, linked through under the “how to” section.

The usual 43mm RFM scale spinner – which we use for almost all our builds – is again a good fit – even with a difficult fuselage shape to build a motor into.

Ventus 2c and Diana 4 – fuselage servos

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It’s often the small things that take up a lot of time. I spent quite a few hours building the frames/setup for the servos in the fuselages of the Ventus 2c and the Diana 4, as well as the bulkheads for the landing gear and the towhook of the Diana 4.

The picture below shows:

  • The two units for the rudders. I will use the usual kevlar wire pull-pull system, using a small pulley that was designed and built within our club ages ago.
  • The servo frames for the elevator servos. These are built into the vertical stabiliser and then connected to elevator using a carbon rod with 2.5mm (Ventus) or 3mm (Diana 4) threaded metal rods glued into the ends.
  • The bulkhead for the towhook servo and the towhook entrance.
  • The landing gear with bulkhead and servo setup.

Diana 4: installing the landing gear

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The Diana 4 will get a retractable landing gear. We’re running low on the stock of landing gear made by our club ages ago and only have a smaller version left. It requires an 89mm wheel rather than the 103mm wheel we used for the JS3 (which uses the same fuselage as the Diana 4). It still looks nice enough though, and the difference will be hardly noticeable. To install the gear I cut out the doors from the fuselage using my dremel with a 0.8mm milling bit. To give the doors a bit of extra stiffness I covered them with a layer of carbon fibre (before cutting them out of the fuselage). The doors are then attached to the hinges, made of steel wires through a brass tube. The landing gear is attached to 4m plywood.

(Most of) the electronics

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Yesterday we got most of the electronics for our Diana4, as well as parts for my Ventus 2c and two other gliders that members of our building team are currently working on (a scale 1:3.5 SB-14 and another Moswey III). The parts were supplied by Leomotion, as usual.

For the Diana and my Ventus 2C we will be using:
Chocomotion 10/10 on the brake and camber flaps
Chocomotion 8/6 on the ailerons
For all wing servos we are using the Chocomotion servo frames and aluminium levers (10/7/5mm).
MKS HV6130H on elevator
Chocomotion 12/9.5 on Rudder

In addition, we will use for the Diana4:
Chocomotion 12/9.5 for towhook
Chocomotion 180/30 for retractable landing gear

All Diana4 will get a FES motor: a Dualsky XM5060EA3-14, with a Freudenthaler Scale Spinner (43/6/0degr – mit Versatz) and a GM 18×10 Scale Prop and a Castle 100 Light ESC.

I’ll also put a FES onto my Ventus 2c, but will still need to determine which motor setup.

We’ve used all components before and have flown hundreds of hours with them – this is our preferred setup.

Urupema – cigarette commercial

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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

Ventus 2c: Stabiliser and Rudder

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Rudder and stabiliser are both built around a foam core. As this plane is supposed to be “super light”, I used 1mm balsa rather than the usual 0.8mm obechi wood. I also used 49gr glass fiber (45 degrees) rather than carbon inserts, as well as a thin (7mm) glass fiber strip at the trailing edge of the rudder and stabiliser. The stabiliser will not have a separate spar, but the carbon tube that also marks the hinge for the elevator will give enough stiffness to the stabiliser. In the middle of the stabiliser is a piece of plywood (with a hole for the screw to fix the stabiliser to the rudder), fixed with two bits of kevlar (top and bottom) to keep it in place.

Last week I built the upper side of the stabiliser and one side of the rudder for the Ventus 2c. Today I finished the lower side, which is now curing in the vacuum bag. I’m using my new small KNF vacuum pump, which seems to be holding up quite well. To avoid having to walk over to the workshop regularly to check all is ok, I installed a cheap webcam in my workshop to guard the vacuum pressure, and put a timer on the plug so that the vacuum automatically switches off at midnight – all so that I can have an easy and worry-free evening :-). Unbagging is tomorrow and then I’ll get to work on the stabiliser of the Diana 4.

Diana 4: landing gear and seat

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For the Diana 4 we will be using a landing gear that is slightly smaller than the one we used for the JS3 – it’s a bit shorter and we’re using a 89mm rather than a 104mm wheel. The reason is that we’ve been using landing gears that were developed within our club and produced externally well over two decades ago. We’re now on the last of our stock and only have just enough smaller ones left for the three Diana 4 that we’re building.

Using a small milling tool made by a club colleague I cut out the landing gear doors and did a dry fit of the gear and the frames to hold the gear and the towhook (made out of 4mm plywood).

Last week I also produced the seat of the Diana 4, using a mould that we made for the JS3. After waxing the mould I covered it with thickened and coloured epoxy resin. Let it settle for a few hours and then put on two layers of 160gr glass. Unfortunately I didn’t have time to let the thickened epoxy rest long enough before adding the glass, so there are quite a few airpockets in the seat. I filled most of them today with some excess epoxy with micro-balloons. I’ll spray it with filler and then gray paint later, so the pockets will not be visible.

Diana 4: 2nd fuselage

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Two days ago we built the 2nd Diana4 fuselage (mine). Today we released it from the form. It’s the best one we built so far. When we built the first one a few weeks ago we used a new resin for the first time(Hexion EP-Harz L285 LF and Hexion-Härter LH 285 (LF1), both from Suter Kunststoffe AG), one that has a much shorter processing time (50 minutes). The advantage is that the when layering the glass, the first layers are more stable and less likely to shift as you’re building up the layers. The disadvantage is that you really need to mix only small quantities of epoxy (we mix 100+40gr) and must time the mixing right. We quickly learned this when building the first fuselage. For the second fuselage we got it right from the start. The result is a fuselage that has much fewer airpockets (haven’t found any so far) and one that’s also quite a bit lighter (1288 instead of 1428gr).

Diana 4: first fuselage in the mould and first assembly

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After our building team colleague and master painter Andi painted the JS3/Diana4 moulds last week, today Georg and I built the first fuselage. It’s always a bit harder to build the first one after a break of almost a year, and are using a new epoxy resin and a different size 160gr glass, which also takes a bit of getting used to. Include setting up the workshop, other preparations, waiting before joining the two mould halves and cleaning up afterwards we almost spent the whole day working.

While we were waiting for the epoxy to cure a bit before joining the two halves of the mould, excitement got the better of us and we put the wing and elevator shells that Georg finished over the weekend on the fuselage of his scratch-built JS3 (the same fuselage we are using for the Diana 4). The result looks great.

Joining the fuselage halves went very well. We will release the first Diana4 fuselage from its mould on Wednesday afternoon.

Chocofly JS3: Short outer wings

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In-between work on the Ventus 2C and Diana4 I installed the servos and IDS system in the new short outer wings for my Chocofly JS3. It’s now “ready to race” :-). Installing the servos is significantly easier since Chocofly started including the gaps for the servo rods and servo links in the wing moulds. It’s still a fiddly process to get the IDS installation right, but it came out very well. I like the colour of my new winglets and thought I’d go for the “Rapture” decals in grey this time.

Diana4 and Ventus 2C: Wing joiners and ballast tubes

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In-between other tasks I’ve been preparing the sleeves for the wing joiners and the ballast tubes for the 4.5m Ventus 2C and the 5.14m Diana 4. I’ve also given my new vacuum pump a test run and have done most preparations to build the elevator and rudder for the Ventus 2C.

The sleeves for the wing joiners are done as usual: first liberally apply Teflon bike lubricant to the wing joiner and wrap it 1.5 times with a thin plastic bag. Then pull over a kevlar tube and wrap it with kevlar rovings. Then tightly wrap the whole thing with tear-off fabric, put a weight at the end and hang it out to allow the epoxy to cure. We always leave the sleeve on the wing joiner while building the wings and only pull out the wing joiner once the wing shell is done.

 

 

Urupema – new pictures and a first cockpit picture

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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!

New Project: Diana 4, scale 1:3.5 (5.14m)

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In 2016 the company Avionic purchased the rights to produce the manned version of the Diana2 glider – the 1:3.5 and 1:3 scale versions of which are among my favourite gliders. The Diana 3, production of which started in 2017 wasn’t really interesting to build – essentially a Diana2 with a fuselage to accomodate bigger pilots. But the first drawings of the Diana4, released in early summer this year, really got our interest. As you can see on the picture below, the fuselage is almost identical to that of the JS3. The wings are essentially the Diana2 wings, extended to an 18m version on the inside.

The decision to build this plane in scale 1:3.5 was taken quite fast. We have moulds for the JS3 fuselage, which we can use to do the fuselage of the Diana4. Georg also rapidly did a new version of the plans of the Diana2 wings, extending them and adjusting the root to the JS3 fuselage. He also designed the elevator, based on that of “our” JS3 and Diana2.

Georg will be progressing rapidly on his build over the next few months, and his glider should be flying in early spring – well before the maiden flight of the manned version, scheduled for June 2023.

So far we’ve finished cutting the foam for the wings and elevators and I’ve built the wing joiners. We hope to build the first fuselage early next week.

This will be an awesome plane. It’s a combination of our two favourite gliders, the JS3 and the Diana2. The dynamics of the Diana2 wings in combination with higher wings and a shorter fuselage than the Diana2 will make it an ideal slope and thermals gliders. Looking forward to this one.

More blog posts on this to follow, categorised under the Diana 4 tag.

 

New Projects for Winter 2022-2023

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I’ve been doing some preparatory work for new projects over the last few months already – in between other tasks – but I now finally have time to start getting into building mode. An I have a luxury problem: too many exciting project opportunities! Work has started on the following new scratch builds:

  • A scale 1:4 Ventus 2C (4.5m): A few years ago I went to pick up a DG1000 fuselage that I purchased from a retiring pilot. In his workshop there was this really pretty fuselage, which he agreed to sell to me for a few Francs. When I showed the fuselage to colleagues on the club they got all excited: it’s a fuselage that was built by a colleague in our club almost 20 years ago, from moulds and plans that are still around. In fact there are also still a few built planes around. This summer my mate Georg did a full revision on his and stripped out the landing gear, with the result that he got a really wonderful and surprisingly performant 4.5m glider weighing less than 5kg. The plane fills a “gap” in my collection of gliders, in the sense that it’s easy to hand-start on days with little wind. I’ve decided to give this build priority for this winter. I’ve built the wing joiner, have the rudder and elevator parts ready to build. Together with Georg we also cut the foam for the wings.
  • A scale 1:3.5 Diana 4 (5.14m): this one will be 2nd in my priority list, and I’ll be building part of it alongside the Ventus. More on that in a next post.
  • A scale 1:3 Diana 2 (5m): The 5m Diana2 was the first Diana2 model built in our club and as far as I’m aware anywhere. It was a huge success within our club, but was quickly overshadowed by the smaller 4.28m, of which the Chocofly version has become famous as one of the best slope gliders around. I’ve been wanting to build the 5m version for ever. We still need to build a fuselage for myself and for Andi. I’ve yet to decide if I will fit it with my Baudis 5m Diana2 wings, or whether I’ll build my own set of wings. I built a wing joiner last week, but the rest of the plane will be for next winter.
  • A scale 1:3.5 Monnett Monerai (3.43m): My mate Richi has been planning to do a model of this US 12m kit glider for a while. It’s something very special. It’s also an easy build. Richi has done the plug for the fuselage pod (it’s a pod and boom glider) and is having the boom produced by colleagues in a professional glider manufacturer. I’ve produced the wing joiners for Richi and myself. I’ll work on this one on and off, depending on how other projects progress.

There may be one or two further surprises that I’ll report on as they appear :-)(I’m expecting something from the Ukraine, but the delivery of that is uncertain for understandable reasons) .

Chocofly JS3: new winglets and short outer wings!

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It’s been a while since I last updated my blog – keeping busy with other things! Now that winter has fully arrived and I have a bit more time on my hands again it’s time to post a few updates.

The first exciting news is that I received new winglets and short outer wings for my Chocofly JS3! I lost my winglets on the slope at the end of August (see two posts back), and the new ones got stuck in Chocofly’s delivery chain. I finally got to pick my new winglets up with Dani yesterday and fitted them to my long outer wings this morning. I also decided to go for the rapture logo in grey instead of white (looks better in real life than on the picture…). I’ll be building the servos into the short outer wings over the next week or so, in parallel to my other projects. My Chocofly JS3 is now ready to fly again. I’m particularly looking forward to finally maiden the version with the FES fuselage on our club’s airfield – will be an awesome thermaller :-).

Chocofly JS3: FES Fuselage

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I’ve been mostly flying my Chocofly JS3 on the slope. For my club’s airfield I have my scratch-built JS3, which is lighter and has more wing-flexibility (allowing for awesome thermalling). But I’ve very much grown to like the Chocofly JS3 and am keen to give this one a go at our club’s airfield as well. Unfortunately, our club doesn’t allow the use of impellers or noisy motors – it’s in a very quiet and sensitive area. To enable me to fly the Chocofly JS3 at my favourite airfield I thus ordered a 2nd fuselage a (long) while ago.

The 2nd fuselage arrived a few weeks ago. It’s in the usual excellent quality. Initially I considered installing a landing gear, but in the end decided against it. The reason is that I’d like an even lighter version of the JS3 for situations where lift is very bad, especially in early spring or late autumn. My Chocofly JETEC JS3 weighs around 6.8kg, my scratch-built one around 6.6kg, the Chocofly FES Edition will hopefully end up under 6kg.

The fuselage didn’t need much work to finish. I installed the FES with my usual method. I used the outrunner and ESC combination that I’ve been using for just about every build in the last few years, a Dualsky XM5060EA-14SE with a Castle Lite 100 ESC. On recommendation of Dani (Chocofly) I went for an 18×10 GM scale Propeller and the usual Freudenthaler 43mm scale spinner. The result looks really good. The fuselage is now ready for its maiden flight – once I receive a new set of winglets (see previous post)….

Chocofly JS3: losing the winglets :-(

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We’ve had some really good slope conditions over the past few weeks and I’ve been mostly flying my Chocofly JS3. I just love this glider. It’s my favourite choice if the winds are weaker or, as often happens in summer, when you can expect sudden gaps in lift. The JS3 will allow you to battle through low-lift episodes much better than most of my other gliders.

The many hours on the slope however also showed that the JS3 does have an upper limit in terms of speed. I own an early production version of the lighter GPS edition. I prefer this version as the lower weight and somewhat more flexible wings give it better thermalling properties. But it’s not made for vertical drops, tight loopings and ultra-high speed passes – I own other planes that are (including my other favourite, the Chocofly Diana2!).

The slope conditions were at times however just too good not to test the JS3’s limits. We’ve done multiple high-speed passes at well over 260kmh, but noticed that the winglets were starting to get a bit “noisy”. Ever since I lost the winglets of my scratch-built JS3 in Autumn last year I’ve been keen not to push my JS3s too far. But due to a stupid combination of unfortunate circumstances (of which I am to blame) I ended up in a steep dive with a brief loss of signal. The speed of the dive (260kmh) and the sharp recovery turn out of the dive were a bit too much for my JS3. Upon landing, I noticed that I lost my winglets. I always attach them with a strip of tape over the top and nose of the wing, but they were literally “torn out” of the outer wing, damaging a few cm of the underside of the outer wing. Fixing this is not a big issue and a new set of winglets has been ordered, but I promised myself and my JS3 that I will behave in the future….really!