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Joined: 7/3/2003 From: newton,
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Chic, the material the templates are made from is X-Ray film. It's going the way of the dinosaur, most hospitals are converting to digital films and the stuff is getting scarce. I get one of the techs in the radiology dept. at work to save the test films, they come out with the film clear and it makes great pattern material because you can trace through it and it is very durable. I don't have much left, not sure if I can get any more. On those templates, the large notch for the crutch should be left uncut until you get ready to actually glue the former in place, as the location may vary a bit from the plans. My kit was laser cut by Precision, and is well done, but the notches are a tad off from the plans. I think it better to match the former to the plans and mark the notch more precisely for a tighter fit. The #6 is probably okay, and the one I re-cut, #5, is the one to watch, as the former fits at an angle to the crutch, but the slot is cut square to the wood, which is probably what makes it a tad off.
I glued #3 to one of the fuse sides tonite, after laying the sides/crutch out on the plans and marking the locations of the other formers on the crutch. What I spoke about above, the notches for the formers being off, is really applicable to #3 and #5 more than the others, because they fit on the crutch at an angle. Since the formers have doublers along the edge that make them thicker, the notch must be trimmed at an angel that matches how the former fits. Since I learned this the hard way, my notches are a little big and I have a small gap around the crutch on them. When I glued #3 down, I also mixed a little epoxy and added some milled fiberglass to it to make a "putty" to fill those gaps. So-- the former is glued with epoxy at the crutch and bottom brace, but aliphatic along the sides of the former. The former is kept vertical to the fuse side by using a small carpenter square taped in place while the glue dries, and the former is weighted with whatever heavy items are around to make a tight bond.
One thing I did befor gluing up the former was to dry-fit the three cabin formers to see just how well, if at all, my modification to #5 worked. Keep in mind that this is just a mockup with the clamps holding things in place, but you can see that it really changes the wing root and rear of the cabin.
< Message edited by khodges -- 1/25/2008 5:05:30 AM >
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Club Saito #2, WACO Brotherhood #20. What other trouble can I get into?
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Joined: 10/14/2002 From: Alexandria, VA, Status: offline
Ken, those mods really look good and certainly a huge boost to the scale outline. I certainly don't see why there should be any structual integrity issues at all with the new changes. Keep it up. Chic
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Joined: 7/21/2003 From: atlanta,
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Ken, I just stumbled on this thread tonight. Terrific! I'm glad you're building the Bird Dog, my favorite plane. I've wanted one for years. I wish I had the time to build one for myself. Keep up the great work.
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Joined: 7/3/2003 From: newton,
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Rick, thanks for the interest. Keep checking in, make sure I'm doing it right. You know how it is when you know what you want to do, but just can't make it work, or it don't come out quite like you thought?. I started wondering today if that was going to be the case; had me a bit of aggravation this afternoon. I was fooling with the partial frame-up of the cabin trying to get an idea of how I wanted to proceed with putting in former #5, and I broke one of the crutches, right where I had scarf-jointed them. The wood broke, not the joint, but it is in a spot that will have some tension on it until I can get the cabin framed up completely and the glue dries. So...... I epoxied the crutch at the break, and laminated a piece of carbon fiber tape over the joint, and just in case, I duplicated the carbon fiber over the other scarf joint (picture 1)
The plans don't call for any, but I added doublers to #5 down the long sides and at the bottom, to strengthen it and give a bit more glue surface. When I dry-fit it, there is a LOT of pull from the sides, resisting how the former narrows the fuse. I decided to relieve the crutches between #4 and #5, so I made 3 kerf cuts on each one, just behind #4. Once the cabin is framed and dry, I'll put a bit of the carbon fiber over the kerfs for strength. (also pic #1)
I started the cabin frame-up by gluing #3 to one fuse side, making sure it was perpendicular to the side. Then I stood it upright and glued the other cabin side to #3, also making sure it was perpendicular and that the crutches were parallel. Then #4 went in after aligning it, squaring, etc and clamps were applied and I took a break and let the glue dry. After this is when I broke the crutch.
I also decided to epoxy #5 former, as there is alot of stress there. Got it all glued in and clamped (think I used enough clamps?), and then I also installed the top braces at each of the formers and clamped them down, too. I checked the squareness by measuring the diagonals from each corner made by a former. Between #4 and 5, it was off about 3/16", so I added a diagonal clamp to hold it square until the glue dries. It'll sit overnight, and I'll start again tomorrow.
< Message edited by khodges -- 1/26/2008 5:51:29 AM >
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Club Saito #2, WACO Brotherhood #20. What other trouble can I get into?
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Joined: 7/3/2003 From: newton,
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Didn't do as much as I wanted today. It was nice outside, so I went flying for about half the afternoon. Took my Bud Nosen Trainer, which looks kind of like a cross between a BirdDog and a C170. US-41, 96" wing, 22 pounds; it flies like I hope the L-19 will.
I attached formers #1 (firewall) and #2 (instrument panel). The firewall got epoxy, plus I cut a 1" square hardwood stick into two triangular pieces with my bandsaw, sanded one side to match the curve of the fuse sides, and epoxied them into place in the corners. This firewall ain't going anywhere . The inst. panel was aligned and glued and when the firewall was clamped tight it pulled the fuse in a bit and held the inst. panel tight.
While the front end was curing, I leveled the crutch and glued formers #6-10 in place, making sure they were vertical, or perpendicular to the crutch, and also perpendicular to the vertical centeline of the fuselage. I also marked the centerline of the fuse on top of the cabin formers, #3,4,&5, and layed a stick in the stringer notch on top of the rear formers. Then I sighted down the marks and down the stick to ensure that the fuse was aligned front to back. I had made a sort of jig to set the fuse in just so it would sit flat on the table and to support the rear ends of the crutches.
< Message edited by khodges -- 1/27/2008 4:07:51 AM >
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Club Saito #2, WACO Brotherhood #20. What other trouble can I get into?
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Joined: 7/3/2003 From: newton,
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Today, I got the landing gear plate in place, the tailwheel mount in place, and a couple of longerons and formers. It took all afternoon; I had to re-cut the landing gear plate because the one that came from Precision was not cut perfectly square and was 1/8" narrower than it should have been. It would have worked, but the fit wasn't as close as I wanted. I didn't have any 1/2" ply, so I glued up two pieces of 1/4". It doubled the layers, so maybe it will be more solid, not that anything else but the gear plate would survive in a crash anyway . I had to get creative with my clamps to hold it tight and pull the bottom of former #3 tight to the front of it. I epoxied this plate, but used aliphatic on the smaller triangular piece for the tailwheel mount. It, too, was undercut a tad, but less so and I used the one supplied by Precision. I'm proud of myself so far; I haven't used a single drop of Ca yet
I also glued the bottom main longeron to help stabilize the tail until I get the rest of the longerons in place. When I pressed it in place, I noticed it did not want to rest in the slot in #5, and if I forced it into position it gave the smooth transitional curve along the fuse bottom a slight dip. I checked my full-scale reference pictures and the natural curve the longeron wanted to make is the correct profile. To make it fit properly, I cut a piece to fit the bottom of former #5, revising its bottom curvature (note the line on the piece showing the original curvature, about 3/32" difference), and glued it to the base of the former, like a doubler. Now the longeron fits like it should, and the profile of the fuse stays like it should. I'm not sure why the former came out like it did, I cut the bottom exactly like the original (this is the former I modified earlier to make the cabin rear closer to scale.
To finish up tonite, I glued formers 3a and 3b to the bottom of the fuse at the landing gear plate. Looking at the space that will be covered over betwen the gear plate and the outer skin, between 3a and 3b, I might try utilizing the space for at least the Rx battery. A "trapdoor" on the underside there should be easily camoflaged, and give access to the battery pack; a small hole in the gear plate can be used to pass the wiring through. This is directly under the C/G, and would allow one less thing in the cockpit that needs hiding. Right now, I plan to put the elevator and rudder servos at the location shown on the plans, just forward of #5. This would put them behind the rear seat, so they won't interfere with scaling out the cabin interior.The Rx will also go back there I hope; I'm using 2.4GHz so I don't have to worry about antenna routing. The ignition battery and throttle servo hopefully will go in the engine compartment.
< Message edited by khodges -- 1/28/2008 2:05:35 AM >
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Club Saito #2, WACO Brotherhood #20. What other trouble can I get into?
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Ken, I did put a trap door sort of speak under the plan location for the elevator and rudder servos to give me direct access to them instead of going through the scaled out cockpit to get to them. Wish I had thought about using the area between the landing gear legs as another trap door. Would have been smart for access to batteries or something, again, to cut down on going into the cockpit area. Got a bit antcie and added the step and an open vent on each side of the cowl last night. Did not have alot of time to work. Will finally sand and glass the wings this week. Ken, your build is looking awful good and your being very smart about it. Chic
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Joined: 7/3/2003 From: newton,
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I hadn't really thought about getting to the servos, not a bad thought, so I'll probably look into that as well.I think that I can hide both by using the panel lines in that area to conceal the access panel edges, One other things I plan to do; the filler that fits over the landing gear, I will make as a removable plug. Invariably at some time the gear will need removal for repair. I did the same thing to another plane I had with similar gear mount, it worked well and was not very noticeable, and I wasn't trying to conceal it on that plane. I'm not sure if I'll get anything done today, will post pics if I do.
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Club Saito #2, WACO Brotherhood #20. What other trouble can I get into?
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Joined: 1/31/2008 From: , NJ, USA Status: offline
Hello All. Has anyone here built the l-19 by Bob Rich? Im currently having serious trouble with the fuselage formers. Nothing seems to fit. Please if anyone can help. Photos Info Whatever. Thanks. MJC0074@Yahoo.com
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All Forums >> RC Airplanes >> RC Warbirds and Warplanes >> RE: 25% Cessna L-19/0-1 Bird Dog build 
RE: 25% Cessna L-19/0-1 Bird Dog build - 
. The inst. panel was aligned and glued and when the firewall was clamped tight it pulled the fuse in a bit and held the inst. panel tight. 
. I had to get creative with my clamps to hold it tight and pull the bottom of former #3 tight to the front of it. I epoxied this plate, but used aliphatic on the smaller triangular piece for the tailwheel mount. It, too, was undercut a tad, but less so and I used the one supplied by Precision. I'm proud of myself so far; I haven't used a single drop of Ca yet 
