A friend of mine visited on the weekend to get an opportunity for his son and himself to practice some R/C aircraft piloting. Needless to say, the prospect of having some interested folks around spurred me into getting the Joyrider into tip-top shape… and it gave me the opportunity to try and fulfil one of those wishes left over, as mentioned in my post about taking stock. That is: banner towing.
After drafting a first version of the nose, there’s work to do on the fuselage. So this week, it’s going to be a lot of frames to draw.
Since the Maiden Flight during Summer last year, the Joyrider has spent about one and a half hours in the air, while spending up to eight hours in the workshop and the rest of the time on shelf. It has been a rough ride, with many setbacks. However there’s a happy ending. Today, I’d like to take stock of what happened since the first flight tests.
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.
After the first Center-of-Gravity tests my expectations have been thoroughly adjusted. I have to admit, at the beginning of this project I didn’t waste a thought on a possible failure. Meanwhile, the Maiden flight has become some sort of obstacle to me.
During the last weeks I’ve tried to accomodate weather, family and interested friends while taking patience and easing my doubts. That piled up too high: now or never!
A short remark: My wife thankfully took some video footage. However my PC has quit service, so I can’t postprocess. I will hand in the videos as soon as a new PC is at hand. Meanwhile, some still images will have to do.
Finishing the covering was another milestone for me and I was very confident that the maiden flight would turn out just fine.
Then the first complete assembly came along and with it some new challenges. Namely undercarriage and center of gravity.