Today we maidened the first of our three Diana4 – the one built by Georg. He finished it just last week (having started the build at the end of last year – very fast, as usual). His Diana4 came out at 6.4kg, 7.1kg with ballast.
As always with a brand new plane, it needed a bit of finetuning. Georg started off with the CG of our Diana2 (which has the same wing profile), but that turned out to be too far back. Also mixing in down elevator with the butterfly needed a few tries. Once he got the settings in the right range the plane just didn’t want to come down anymore. There is still some more fine-tuning to do, but it’s a wonderful glider that will surely see much “airtime”.
Sometimes things don’t go quite as planned, even if you’ve done it plenty of times. Installing the motor bulkhead of the Diana4 was a pain. The carbon bulkhead was just a bit too big for the fuselage, and I was sloppy in making the first cut on the nose. I ended up having to remove the bulkhead (fortunately only fixed with a few dots of 5min epoxy) and sanding it down by mounting it on the drill and rotating it on a bit of 120 grain sandpaper. Even the second try wasn’t quite as good as I wanted it to be, but with a few corrections on the fuselage it will come out fine once the fuselage is painted.
In-between I produced two covers of the instrument panel. The first one in the mould that was spray painted, the second one using thickened epoxy as the “basis”. Making these small parts in the mould are good for using left over bits of glass. Two layers of 160gr, or a layer of 50gr, one of 100gr and one of 160gr are more than enough for a robust cover.
The full-size Diana 4 is not yet ready and we don’t have any pictures of what the instrument panel will look like. So I’ve had to make something up. Below is the result. It’s actually almost identical to that of our JS3. The only thing I changed is the logo at the top of the VNE chart. Click on the link below to get a printable PDF file – if that’s of use to anybody.
The first of our three Diana 4, the one that Georg Staub is building, is nearing completion. It came back from the paint shop almost two weeks ago and Georg is now in the process of finishing the wings. It should be in the air in another month or so. So time for me to finish the decals. The decals I’ll be cutting are inspired by the Diana 2 logo, as well as the layout of the Diana 3 and the plans of the Diana 4 available on the internet. As there is no full scale Diana 4 as of yet, that’s all we have to work with for now. Linked through below is a full scale PDF of the decals, made by me, in case anybody else is interested and wishes to use them.
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.
After building the two sides of the stabilisers in vacuum I used a balsa/carbon sandwich to build the tips and curves into the stabilisers. A lot of sanding to get it into shape, but the results look good. Both the Diana 4 and Ventus 2c stabilisers are not ready to cover (with 49gr glass).
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 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.
Today I “closed” the horizontal stabiliser of the Diana4 (underside), having built the other side earlier this week. It’s now sitting in vacuum until late tonight. Below the plan and some pictures of the bits that went into it.
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.
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.
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).
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.
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.
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.
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 Monett 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) .
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