I can't argue with the logic of building the wings separately and then attaching to the fuselage. 707s were done this way and they may still be building that way. On Jan 31, 2014 1:22 AM, "Mike T" <mctaglieri at gmail.com> wrote:
> I'm still trying to decide whether to build a KR-2 or a Thatcher CX4, a > recent single-seat aluminum LSA design. These two designs aren't as far > apart as they seem, because a KR-2 can also be LSA compliant. It already > makes the LSA stall speed if you keep it light, and I could use a smaller > VW engine (or just adjust the throttle so the carb doesn't open all the > way) to get it down to the LSA top speed someday. I think the LSA law > would le me fly the plane fast for now, then slow it down to make it LSA > compliant if I ever get sick of getting medicals. By contrast, he CX4's top > speed is 135 mph and the VNE is 155, so it's not even as fast as the > fastest LSAs. > > But whatever plane I build, I want to build it in the living room of my > house. As I mentioned here before, I have woodworking and metalworking > machines in the basement, but that doesn't leave room for the plane down > there. Also I have a garage, but it has no heat and limited electricity, > and sometimes it's wet. So for much of the year I'd be unable to work > there, or I'd have to come home from work and fire up a heater for hours to > warm the garage. But with the plane in the living room, it would be warm, > dry, and staring me in the face whenever I came in the door, so I'd have an > incentive to keep working on it every day. > > But there's a problem doing this with a KR: The center spar is so long I'd > never be able to get it out again after the spar was installed, so I'd have > to move it to the garage after the boat stage. The spar is so long is to > allow for flaps and wing tanks, which I don't want, but trying to change > the design of the spar and wings would be way too complicated. > > So I was all set to give up on the KR2 (and I even bought plans for the > CX4) when I saw this article in the KR Newsletter of October, 1984 (#112, > p. 3). This is a guy who built his wings entirely off the plane. He was > doing it to make a better wing (and I think he's right). But doing this > would also solve my problem of getting the plane out the door when it's > done. And it would make it easier to build the wings exactly alike by > clamping the center spar to the worktable and building both wings at once. > (And of course you could flip the spar upside down easily, so you could > foam, glass, and finish both sides easily). Here's the guy's article, > between the dotted lines. > > ----------------------------------- > Here's a controversial one! I am building my wings *out* of the fuselage, > on a separate table, in a jig. I believe I will get a guaranteed true > wing, with the correct washout. This again steals from model-building > techniques. To be able to do this at all requires a way to remove the wing > from the fuselage, and to reassemble it to the fuselage after construction. > You can't obviously, *slide* the wing back into the fuselage spar slots. > > Here's what I'm doing. I completely installed the center spars in the > fuselage *except* that they *aren't glued.* Turning the fuselage onto its > top, I cut a slot through the bottom of the fuselage so the spars can be > lifted out, rather than slid out through the sides. When the wing is > finished, I'll just drop it back into the spar slot. I'll replace the > lower longerons, which had to be cut to replace the spar slot, by gluing a > new 5/8 square sub-longeron alongside the one I cut, with a healthy > overlap, scarf, and plenty of reinforcing glass cloth. > > Once the wing is separated in this manner, I can mount the spars on a work > table and be sure they are jigged perfectly into the correct dihedral, > washout, etc. > > This technique was worked out by my good friend Charlie North, who is a > licensed A & P, and who feels the end result will be a stronger, more > accurate finished product. I'll keep you posted on its success. > > Bill Thomas > 9 Pine Acres Drive > Canton, CT 06019 > -------------------------------------- > > Me again. So what do people think of this idea, and do you know if anyone > else has ever done it? Adding longeron and plywood reinforcements after > replacing the spar would add some weight to the plane, but I don't think it > would very much. > > Unfortunately Bill Thomas didn't keep his promise and never wrote anything > else about how this worked out. He later had an ad in the Newsletter for > some unused parts, and years later on KRnet he parted out a KR200 he said > he finished in 1989. He said this was because he was buying an RV and > didn't want the liability of selling the KR, but it sounded as though he > flew it a couple of hundred hours and there was nothing wrong with it. > > I'd be interested in hearing people's opinions about this idea, especially > the opinions of any A&Ps here. (Also, of course, if Bill Thomas or the A&P > who designed this setup 30 years ago are here, I'd like to hear from you, > but that seems pretty unlikely at this point). > > Mike Taglieri > _______________________________________________ > Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. > To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org > please see other KRnet info at http://www.krnet.org/info.html > see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change > options >
