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Here's a better shot of the underside of the hatch, with the side rails shaved down. Also, a pix of the fairleads installation, ready for some repair/fixing up (not my proudest achievement).
Today has been a linkage & soldering day. The elevator link from the servo to the jackshaft goes along the right side of the fuselage and has more kinks than a dog's hind leg. The rudder arm on the servo is cut in a boomerang shape, to eliminate any major differential at this point. Wherever motion is translated from radial to linear, or visa versa, there is the possibility of introducing differential and I don't want it here. I soldered some little washers onto some 2-56 machine bolts which screw into Great Plains clevises for the pull-pull Kevlar cables. This is used on both the rudder servo and the elevator jackshaft, and should give plenty of adjustability. The rudder cables go through two Proctor pulleys on each side to keep things moving smoothly. With the hatch on, the links are just visible on each side but it is pretty good for my pilot and interior. The IP will need some cutaway at its edges but not much.
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I did a few things on the fuselage bottom today. The wing roots are a sandwich of ply and balsa. I don't know if these get glued on or not. I also did the little balsa plate just aft of the landing gear block, which completes the fuselage structure in that area.
Then it was on to the tailskid/tailwheel area which is like building a ship (a small one) in a bottle. The idea was to create a little plate that 'floats' on the rudder cables without any physical connection to the structure other than the kevlar itself. The plate has two little inboard holes for z-bends in .015" music wire that go to little mini-ez connectors on the tailwheel arm. All in all it seems like it will work although I will have to enlarge the slots in the bottom rudder plate to allow for the necessary movement. The tailwheel should rotate about 60 percent of what the rudder does with this particular linkage.
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quote:
ORIGINAL: allanflowers The wing roots are a sandwich of ply and balsa. I don't know if these get glued on or not. I also did the little balsa plate just aft of the landing gear block, which completes the fuselage structure in that area.
If it's like the Snipe, there is a ply "root" that is glued to the fuse sides to provide a solid contact surface (as opposed to the underlying balsa fuse wall. Note that the fuse wing tubes should be flush with the outside of this ply root. On the the wings themselves, the first couple of ribs are sandwiches of ply and balsa (ply on the inboard side). These are the ribs that support the wing tube.
**Allan, actually, I just looked closely at your photo again, and I think you've made a mistake there. The ply "partial rib" is glued directly to the fuse wall balsa and provides some protection to this area when putting on (and taking off) the wings. This ply riblet only extends as far back as the rear wing tube. It looks like you have accidentally used the first ply/balsa sandwiched first wing rib. And on those sandwiched ribs, the ply goes on the "inside."
< Message edited by abufletcher -- 1/28/2008 4:22:26 AM >
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I believe the Pup is different than the Snipe in this area. Both the plans and online manual photos show full length root rib pieces on the fuselage. In any case, it looks like it would complicate covering but I might glue it on after covering. I have been checking both the English and German online manuals because, although I can't read the German, sometimes it has additional photos. Here is the manual photo of this.
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Allan, hmmm...I'm concerned here, but you might be right that the Pup kit is different in this respect. Here's the German text that accompanies the photo you posted:
"Die Flügelwurzel aus 1,5mm Sperrholz und 4mm Balsa können jetzt laminiert werden und mittels der 3mm Federdrahtsteckungen versuchsweise angebracht werden."
I would translate this as follows: The wing root from 1.5mm ply and 4mm balsa can now be laminated and by means of the 3mm (music wires?) TENTATIVELY/PROVISIONALLY fitted.
This is somewhat ambiguous since it's unclear whether the "wing root" refers to part of the wing or a part on the fuselage. The key word here is "versuchsweise" which is literally "attempt-wise" and to me (and I could be wrong) means something like to fit in order to "check the fit." Maybe something like "provisionally fitted." So maybe this photo shows the actual root rib ON THE WING provisionally (and temporarly) mounted in place. But then I see this laminated "fuse-wing-root" in the photo on the landing gear as well.
I really wonder though what purpose this 4mm balsa would serve. That would mean the 4mm balsa rib would be next to the 4mm balsa fuse side which seems like an awful lot of easily compressible balsa in a key area. Maybe it is just some sort of spacer for some other purpose.
Best to ask Chris.
< Message edited by abufletcher -- 1/28/2008 6:00:38 AM >
This is just a scale feature. The full size had a wing root attached to the fuselage so I thought it would be nice to do it the same way. There's no need to glue it to the fuselage and it isn't part of the wing either. Mine was glass covered and painted.
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It could of course be glued to the fuselage, but it's not necessary. It's held quite adequately by the two 3mm piano wires wing dowels. Also, you'll have one hell of a hard time applying your covering around it. Another option would be to cover the fuselage first and then glue it to your covering, but again, it's just not necessary. I glass covered it's edges because I wanted a nice smooth surface to paint. It was treated the same way I treat all glass covered surfaces, with primer added and sanded down until I have that nice smooth surface. CT
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Thanks for the info on that, Chris. Today I installed the little .8mm plywood pieces that finishe the fuselage just above the wing. I decided to go a little extra and make flush the pieces (actually almost flush but not quite), which involved scarfing the rear of them to paper thickness and notching the formers a bit. Also I like to seal off any gaps using little balsa strips between the formers. Next was detailing the main underside hatch area with corner blocks and flanges, again to better seal off that area. The hatch is ply.
< Message edited by allanflowers -- 1/28/2008 10:46:06 PM >
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I built up the Sullivan 10oz. flex tank and fitted it into the plane (a three tube system (fill, vent, and carb feed). This was virtually the only tank I could find with this capacity that didn't push this tight fuselage package beyond reason, in terms of its dimensions. I have used other Sullivan tanks in the past, as well as Hayes, Dubro and a few others too. Frankly they all are crap. There isn't a worse task in building a model airplane than putting the tank together. I have yet to feel good about one upon finishing it. The little brass tubes kink or break when you try to form them and that plug thingy is a %$#& nightmare. It is a miracle that any of them work at all. I think the engineering that goes into them is criminal and the expectation that an average modeler can put them together defies all logic. They are basically giving you raw materials to mash together, not an engineered precision product. Sorry about my rant but model plane tanks are the work of the devil. It's enough to make you go electric. The installation in this model is critical because the length of the tank pushes the tubes pretty far into the engine area. There is no room to spare before running into the carburetor. Hooking up the hoses will be a big frustrating challenge too.
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Well for one thing your'e using a tank larger than required, for another thing there are several devices to aid in bending the tubing, and for a third thing Hayes tanks are so far from being crap that they are the cream that rises to the top of the available crop
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RE: CD Scaledesigns Pup build - 
