Based on the design variations, I’m moving on to the actual planning and start to blueprint the nose. If possible, it is supposed to give the aircraft a semiscale appearance and that means I basically have to start from scratch.
In order to create parts repetitively and precisely, the blueprinting is going to be computer-assisted. In theory I could draw on paper, scan the diagrams and print them. However, I would lack the 3D preview and applying adjustments is going to be much more time-consuming.
In order to build the Thermy 4 I will need building boards, which are in widespread use with model aircraft builders. They serve two purposes: First they are supposed to provide an absolutely even surface because most workbenches sag over time, which means one can’t build really straight wings or fuselages on top of them. It’s easy to check it out at home, simply put a spirit level on top of the workbench and look for the gap in the middle, which one almost always will find. Second, building boards facilitate storing subassemblies while one is continuing to work at other parts. And since my workbench is frequently needed for other purposes than the current project, one doesn’t want it to be cluttered with, say, a clamped half of a fuselage.
As already mentioned at the start of the construction report, I’d cast an intermediary eye on the Lentus Thermik by Multiplex. I especially like its semi-scale appearance, that gives it a similar look as modern soaring planes. Most notably the bulbous nose and the T-shaped tailplane are spectacular and provide a great silhouette during flight.
Since I’ve braced up and actually want to build the Thermy 4, I want to begin with getting clear about one thing: What do I actually want?
The question isn’t quite as trivial as one might think. I’m planning big on this airplane. That is, I want to incorporate as many features and wishes as possible because I hope to keep this bird flying for the rest of my life. So today is about the demands that I’ve got for this model.
In March 2019 I happened onto an issue of the FMT, which included the first part of the diagrams for the Thermy 4. Right away, I knew: That’s what I’ve been looking for!
The model incorporates everything what I’ve wished for: great wingspan (4 metres), take-off weight below 5 kilograms so it’s legal to fly outside of model aerodromes, flaps and an electric motor, enough space for own, further ideas.
Now, after two years of wavering and brooding, it’s finally on. With this new construction report I will try and document my attempt to build my own, larger sailplane.
By constructing the steps the flatcar has gained some character, but of course this can only be the beginning. The next topic is to build the stake pockets. I’ve already constructed stake pockets for my porter’s tender and gained some valueable experience. I’ll profit from it while moving on.
By mounting the queenposts the waggon’s substructre is now ready for the turnbuckles. The prototype is used to adjust the trusses’ tension in order to avoid the waggon’s floor to sag. I decided to go for a scratch-build again, since the cast pieces are currently very hard to come by and on top of that they would have been the weakest link in my current construction. However, as a matter of fact it’s very time-consuming to build them manually.