Rough 1/2 scale model of my Part 103 folding wing airplane project to check the operation of the system and test its solidity.
I first check that the folded wing passes well above the tail. We see that it passes widely, thanks to the inclination of the axis of the rotation pivot (see previous articles), we can even enlarge the vertical tail.
I then move on to the wing load test to check the strength of the fasteners.
The full-size aircraft would have a maximum total weight of 240kg, at 1/2 scale it must therefore weigh 8 times less, or 30kg. So I put the model on its back and loaded the wings to 6g or 180kg. As it didn’t break I went up to 226 kg or 7.5g and left the load for more than 3 hours. There were therefore 113 kg on each wing, (60 bricks of 1.6 kg + the 17 kg wing/ board = 113 kg) distributed all along the 25% of the chord (see photo). The right wing was held by 6mm rod ends and the left one by 5mm rod ends
1: Strut attachment to the fuselage:
2: Strut attachment to the wing with a 5mm rod end:
3: Attachment of the wing to the fuselage with a 5mm rod end. This is the attachment that serves as a pivot for the wing:
Results after dismantling:
No attachment is deformed, no rod end is twisted.
The rod ends after dismantling:
The rod ends are standard models from ISB INDUSTRIES supporting a static load of 470kg for the 5mm and approximately 600kg for the 6mm.
The 5mm and 6mm rod ends that attach the struts to the wings move perfectly, with no friction, BUT the 5mm rod end which attaches the wing to the fuselage and acts as a pivot is slightly stiff, so it seems it is too weak for this load. For the 6mm rod end used on the other side the stiffening is hardly noticeable, let’s not forget that it has been overloaded, so it should be suitable for a model of this size.
For the real plane I suppose that it would therefore be necessary to use rod ends supporting a static load of 600×8= 4800kg for the 2 pivots and smaller ones for the struts. Such rod ends are 16 to 25mm size and weigh between 190 g and more than 500 g depending on the quality.