Aristo-Craft D17s Staggerwing
08-23-2016, 08:04 PM
#26
Thread Starter
Yeah, I had that happen in other circumstance. To clarify I meant that the tubes are sanded flush and you could build a plug that used a swept antenna as a gripping surface.
After considerable measuring, remeasuring, triple checking incidences and measuring again I got the lower wing saddles glued in and the wing plates glued in. I determined the geometric center line of the wing and referenced every thing to the centerline of the fuselage. I was rocking along until I snugged up all of the wing mounting bolts. I quickly saw that the lower wing was cattywampus. The starboard wing tip was about a quarter inch aft of the port wing tip. I got lucky though, I was able to sand about one sixteen of an inch off the front of the starboard wing saddle and every thing seems to have settled into place. I will have to adjust the bolt holes in the lower wing. I was going to dress the bolt holes with some sixtyfourth inch ply to keep the balsa from crushing so the tweaks wouldn't impact the structure anyway. With the wing mount plates in place I gave myself some room by trimming out the center of F4.
After a lot of trimming and sanding I got the saddles for the stabilizer glued in. The stab is just there for reference for the moment and isn't glued in yet. The kit provides these hard balsa blocks for either side of the rudder. I my substitute a couple of pieces of lighter balsa. This is mostly the work of yesterday and the day before. Today was spent helping my eldest with his plumbing although I did whip up a new break in stand to replace the one that didn't get packed when we moved.
Last edited by mgnostic; 08-23-2016 at 08:07 PM.
08-29-2016, 08:30 PM
#28
Thread Starter
I've got a new Thunder Tiger .40 on the test bed for break in. It was a door prize at the local fun fly. It started on the first bump from the starter and after running a couple of tanks through it it seems like it will be a good running engine. The only quibble I've had with the motor is that it seems to dribble oil between the front and back halves of the muffler. That may be a result of running break in fuel with a little added castor oil.
Back to the airplane I have started planking the fuselage. The planks aren't trimmed or sanded yet. The instructions are a little sketchy on where to plank and it isn't illustrated well on the plans. The instructions tell you to slice 1/2 and 1/4 inch strips with most of the strips being a quarter inch wide. The instructions do make a point that one should be careful not to plank over the lower wing mount. Hmmm, go figure. It also instructs that after the planking is done one is to cote all of the planking with cement. Super glue was available by the mid seventies when this kit was made but instructions assume the use of Ambroid or similar. I guess a nice skim coat of Ambroid would make a nice primer for a doped finish. I may add a little more planking on the starboard side just so that I can have something to use to simulate the cabin door. I have also taken out the upper part of F-5 between the upper wing mounts. The wing mounts do a good job of tying the fuselage sides together and removing the upper part of F-5 gives better access to the fuselage interior. By my next post I should have some pictures of the fin and rudder and a redesign of the interplane struts that will make them both prettier and stronger.
Back to the airplane I have started planking the fuselage. The planks aren't trimmed or sanded yet. The instructions are a little sketchy on where to plank and it isn't illustrated well on the plans. The instructions tell you to slice 1/2 and 1/4 inch strips with most of the strips being a quarter inch wide. The instructions do make a point that one should be careful not to plank over the lower wing mount. Hmmm, go figure. It also instructs that after the planking is done one is to cote all of the planking with cement. Super glue was available by the mid seventies when this kit was made but instructions assume the use of Ambroid or similar. I guess a nice skim coat of Ambroid would make a nice primer for a doped finish. I may add a little more planking on the starboard side just so that I can have something to use to simulate the cabin door. I have also taken out the upper part of F-5 between the upper wing mounts. The wing mounts do a good job of tying the fuselage sides together and removing the upper part of F-5 gives better access to the fuselage interior. By my next post I should have some pictures of the fin and rudder and a redesign of the interplane struts that will make them both prettier and stronger.
08-30-2016, 08:45 AM
#29
I've got a new Thunder Tiger .40 on the test bed for break in. It was a door prize at the local fun fly. It started on the first bump from the starter and after running a couple of tanks through it it seems like it will be a good running engine. The only quibble I've had with the motor is that it seems to dribble oil between the front and back halves of the muffler. That may be a result of running break in fuel with a little added castor oil.
Back to the airplane I have started planking the fuselage. The planks aren't trimmed or sanded yet. The instructions are a little sketchy on where to plank and it isn't illustrated well on the plans. The instructions tell you to slice 1/2 and 1/4 inch strips with most of the strips being a quarter inch wide. The instructions do make a point that one should be careful not to plank over the lower wing mount. Hmmm, go figure. It also instructs that after the planking is done one is to cote all of the planking with cement. Super glue was available by the mid seventies when this kit was made but instructions assume the use of Ambroid or similar. I guess a nice skim coat of Ambroid would make a nice primer for a doped finish. I may add a little more planking on the starboard side just so that I can have something to use to simulate the cabin door. I have also taken out the upper part of F-5 between the upper wing mounts. The wing mounts do a good job of tying the fuselage sides together and removing the upper part of F-5 gives better access to the fuselage interior. By my next post I should have some pictures of the fin and rudder and a redesign of the interplane struts that will make them both prettier and stronger.
Back to the airplane I have started planking the fuselage. The planks aren't trimmed or sanded yet. The instructions are a little sketchy on where to plank and it isn't illustrated well on the plans. The instructions tell you to slice 1/2 and 1/4 inch strips with most of the strips being a quarter inch wide. The instructions do make a point that one should be careful not to plank over the lower wing mount. Hmmm, go figure. It also instructs that after the planking is done one is to cote all of the planking with cement. Super glue was available by the mid seventies when this kit was made but instructions assume the use of Ambroid or similar. I guess a nice skim coat of Ambroid would make a nice primer for a doped finish. I may add a little more planking on the starboard side just so that I can have something to use to simulate the cabin door. I have also taken out the upper part of F-5 between the upper wing mounts. The wing mounts do a good job of tying the fuselage sides together and removing the upper part of F-5 gives better access to the fuselage interior. By my next post I should have some pictures of the fin and rudder and a redesign of the interplane struts that will make them both prettier and stronger.
Now on the comment of "I guess a nice skim coat of Ambroid would make a nice primer for a doped finish." I would test this on a scrap piece first, some glues seal the wood to the point nothing penetrates and the dope may not adhere well. I have never used Ambroid glue before but its better to error on the side of caution.
08-30-2016, 10:43 AM
#30
Thread Starter
On the new engine be very careful with any strike, tightening, or stress applied to the needle valve assembly. I have the .46 Pro and the threads holding it to the carb body are very shallow and easily stripped or damaged.
Now on the comment of "I guess a nice skim coat of Ambroid would make a nice primer for a doped finish." I would test this on a scrap piece first, some glues seal the wood to the point nothing penetrates and the dope may not adhere well. I have never used Ambroid glue before but its better to error on the side of caution.
Now on the comment of "I guess a nice skim coat of Ambroid would make a nice primer for a doped finish." I would test this on a scrap piece first, some glues seal the wood to the point nothing penetrates and the dope may not adhere well. I have never used Ambroid glue before but its better to error on the side of caution.
08-31-2016, 07:06 PM
#31
Thread Starter
Not too much to show today. I framed up the fin and rudder. Some of the fin parts were too long and required a little trimming and as you can see in the picture the rib notches in the rudder didn't quite line up.. Unfortunately sanding the planking doesn't make for an exciting picture.
09-06-2016, 07:22 PM
#33
Thread Starter
Working a bit on the interplane struts. The stock kit uses a small tab on the upper and lower rib with the strut made of three pieces. The pieces that simulate the fairings seem to just sort of float. As designed the struts just attach to the 1/16 inch ribs. The whole things seems pretty fragile and if the strut gets bumped you end up with a broken rib. I have incorporated the tab and fairing into one piece and made it so that it keys into the spars. With a bolt on wing any strike that has enough force to shift the wing is going to do pretty major damage anyway. I assembled the struts while the glue was setting up so that every thing was in alignment while the glue dried. I am going to put a 4-40 blind nut in each of the struts so that they can be assembles with just a couple of 4-40 screws.
09-07-2016, 08:13 AM
#35
Thread Starter
I think the idea for the struts came from a Sig Profile Ultimate Biplane that I built years ago.
09-07-2016, 11:08 AM
#37
Thread Starter
Funny you should say that. I have actually started on it but I guess I hadn't done it when I took any of the pictures.
09-14-2016, 08:14 PM
#39
Thread Starter
Just the one picture tonight. It shows two things.One is the aileron servo in the upper wing. It is a ball bearing mini servo. The torque may be a little on the tepid side but it only has to move the one relatively small aileron. Short of dropping some cash on thin wing servos this is about the only way to go with dual servos. I suppose since the wing is flat It would have been easy enough to do torque rods. I could also have gone with bell cranks and a tie rod. Since this isn't a precision aerobatic plane that would have been perfectly adequate but I had the servos and this installation was pretty straightforward. . The other thing of interest in this picture is a fabric aileron hinge. These may still be available but I haven't seen any in a decade so I made my own. The hinge is essentially two strips of iron on fabric that are sewn together. The fabric is ironed to the top and bottom surfaces of the parent surface and the control surface with the sewn hinge at a beveled point that defines the axis of the hinge. This produces a gap free hinge that is really very strong. If the hinge axis is at the upper surface of the control it is possible to iron what ever covering you are using right across the hinge, taking care to adhere the covering to the hinge line. I will post pictures once I get into covering the upper wing as it produces a neat gapless hinge. I would rate the end result at least as strong as CA hinges.
09-15-2016, 08:39 AM
#41
Thread Starter
I generally use CA hinges. The sewn hinge is nice where the hinge line is biased to one side or other of the surface. Mostly it was a case of I haven't used this technique in a while because I couldn't get the hinges and I wanted to see if I could make my own.
I will probably use CA or pinned hinges on the tail.
09-18-2016, 06:33 PM
#42
Thread Starter
I had to fix a mistake. F-11 is a small former that glues to the back of F-10 that forms the back wall of the cockpit. F-11 has the notches for the stringers and should sit proud of the top of F-10 by about 1/8th inch. I misread the plans and glued F-11 flush with the top of F-10. As a result there is a noticeable step from the trailing edge of the upper wing to the fuselage. To fix this I glued in a stip of stock across the top of F-11 and then added material to the tops of the stingers and then sanded to the appropriate outline. It looks like it will work out okay.
The directions and plans describe the fillets on the lower wing as "optional" but a Staggerwing just wouldn't look right without them. I think that "optional" must have been a code phrase that meant "it will look a lot better with fillets but we aren't going to tell you how to do it." Improvising fillets is kind of like making sausage. The results are tasty but the process isn't pretty.
I measured the width of the fairings as shown on the plans and cut out the rear bottoms from sheet stock. I measured the height and width of the former and used a spray paint can to set the curve. I covered the lower wing so that I could have it ready for this process. I made templates out of stiff paper to mock up the pieces of the fillet and then cut the lower part of fairing that overlaps the wing from 1/64th ply. Covering the wing with the backing from some covering allowed me to butt glue the bottom part of the fuselage in a way that conforms well to the wing.
Using more paper templates as a guide I cut the upper sections of the fillet from more 1/64th ply, forming it with an over lap that could be trimmed to match the lower section. I steamed some 1/16 balsa for the fillets but the 1/64 bends easily and lays flat against the fuse just like the real thing so I went with it. I faired the bottom sheeting into the stringers. There is still some filling and sanding to go but I am happy with the results.
09-19-2016, 02:42 PM
#44
Thread Starter
Thanks Flyer, I think I'm about to the 90% done, 90% to go stage.
09-21-2016, 09:09 PM
#45
Thread Starter
I went ahead and covered and hinged the tail surfaces so that I could start figuring out the pushrod and servo locations. Nothing like HD photography top show off all the little imperfections in your covering job. I also started working on the tail cone. The cone started off as a 1 and 1/4 inch thick block of wood. I have it carved generally to shape but adjustments will have to be made. Although I was careful not to trim off any length it still came up a little short. I'm going to have to add about 1/4 inch to the length and fill in some of the notch I made for the elevator crossbar. On a larger/more ambitious model one could probably hide the control arms for the rudder and elevator. The elevator uses CA hinges and the rudder uses Dave Brown hinges.
09-22-2016, 08:36 AM
#47
Thread Starter
The tail cone was a 1&1/4 inch thick block of wood that was sawn to profile. Pretty typical, I suppose for a kit of this era. I've built more modern planes that substituted a stack of 1/8th sections that were glued together. Probably a little lighter if one is careful with the glue.Once I get the shape where I want it I will probably hollow it out.
Last nights whittling scratch. An airplane just isn't complete without a little blood in it.
09-23-2016, 08:23 PM
#49
Thread Starter
A couple of views of the tail cone. A good thing that it was an attractive piece of wood because I spent quite a chunk of time trimming and sanding on it. Part of that was my fault for notching it before discovering that it lacked a quarter inch lining up with the trailing edge of the rudder. I did hollow it out somewhat before adding the sheet. I also had to put back material where I notched it. to get every thing to line up properly. The third picture shows the flowing lines of many of the stringers. The top, bottom and side keels hold the formers in location while the stringers are added and the instructions state with good reason that you should add stringers on alternating sides. The last two pictures show where I have glued in my servo rails. Nuthin' fancy, just a rudder, elevator and throttle servo. It can be seen where I have removed the center sections of the formers in the cockpit area. The wing mounts and servo rails maintain the structural integrity. In fact it is probably ever built.
For those of you who are interested in building your own Staggerwing, I went by LazerWorks to pick up some hobby supplies and the owner showed me his prototype for his laser cut version of the kit. I purchased my original kit from him after he was done scanning and measuring it. Although not yet complete it looks like a considerable improvement on the original kit. He has added locating tabs to many of the parts and resolved some of the engineering issues that I have noted in my build. His Kit will also have an included jig that is part of the building process for the fuselage that will help with the "building in the air issue. I didn't have my fuselage on hand to compare but I expect that his version will be noticeably lighter in weight due to the better selection of light ply and not relying on "Japanese Cedar". It is pretty cool that some of these long out of production kits, some of which came and went long before I got in to the hobby, are now available on a cut on demand basis.
09-24-2016, 11:05 AM
#50
I know what you mean! I do what I think is a great covering job but then look at a photo of it and just get depressed. I'm sure it looks great in the flesh.Your build is coming along great and she looks like she will be a real beauty. Always loved the staggerwing!