Postby MalcolmDouglasPorter » November 14th, 2014, 9:17 am
Hi Denis, thanks for your support. This thread is for me to keep a record of this project, to learn stuff, and maybe others can learn from my mistakes? I do understand a little about geometry and the physics of aircraft, but not enough, so I need to pick brains from time to time. I am not up to speed with the new generations of adhesives; this has all changed since my previous forays into model aircraft.
On that point about adhesives, thank you John for your suggestions above. I will be sure to buy all the required types of sticky stuff that will doubtless be needed.
With regard to “the gaps”, we must get this into perspective! The errors I refer to above are all cross halving joints; therefore each joint will have four edges that will stick together. Should there be an error in cutting one of these joints, then the maximum error can only be one of the four edges with a small gap. I will deal with this (if this occurs) by gluing in a sliver of wood into the gap. My contention is that this will actually be a stronger joint for this remedy. All main fuselage frames on this model will have seven of these cross halving joints, the “C” section frames will have eight, plus two extra ¼ inch stress bars which in fact runs from B4 through the six “C” frames and the two “D” frames, nine frames all of which are ply, the rest of the frames will be balsa. The stress bars will be braced with ply gussets longitudinally. The main stress area will be between C2, C3 and C4 (as mentioned earlier ^) with the ¼ inch stress bars, should provide all the strength required between the wings and the fixed landing gear. These areas are where there can be no errors and gaps etc. The wing attachment box will be constructed from 1/8 ply at the sides, ¼ ply top and bottom, and will be finger jointed. This must be absolutely accurate, and if I make any errors, I will need to remake the parts and not try to remedy them. This box is fitted between frames C2 and C3 and is at the balance point of the aircraft. There may seem to be insufficient longerons, but I am going to skin this with balsa, probably 3/32”, creating a monocoque structure, coated in resin and woven glass, it should be as strong as steel?
There are possible issues with the engine nacelles at the moment, I need to have another look at this arrangement and maybe design some improvements to the stressed areas. Other than this, I have no real worries. I am going to visit Richard Hughes in the next couple of weeks to discuss my wing design and look for any improvements that may be necessary, but I am reasonably happy with the design so far.
In the meantime, there is the AGM. Perhaps we can say hello?