cracker39

I decided to build a seaplane, even though I’m still learning to fly my trainer. I think I’d almost rather build them than fly them, but what good is building one if you don’t fly it. I call this a scratch build, although a friend gave me a 20 year old 60” wing from an Eagle trainer, so I’m repairing it and will recover it and use it. But, the rest will be built from my own plans I’ve made up. I took ideas from several other seaplanes, including the Seamaster, Sealane, and Pondmaster, so you’ll see some of each of them in my design. The plan images I’ve used so far don’t shot the wing floats, but it will have them.

I finally got my plans as complete as I could and printed out a full size set tiling the images onto 11”x17” and letter size paper as needed to splice them together. I decided to start building, even though I may not finish for a couple of months. That’s OK, because I’m still learning to fly my trainer. And, I may take a break as a friend is getting a seaplane from a friend of his and asked if I wanted to frame it up for him as he doesn’t have the time and I do.

I started a picture album (link is below) to store my pictures. The first shows my fuse side pieces (for one side) and my top view printout. I bought 6” wide sheets of lite ply and balsa (poor planning) and the overall dimensions of the fuse are 7 1/2” (from the bottom to the raised tail piece) so I had to piece the sides together. The balsa has one joint and the lite ply two joints so I could make sure the joints were in different locations for strength.

I stacked the joined balsa pieces between ply pieces and secured them with 1/2” brads outside the outlines. I used my band saw to cut out the outline and my bench sander to smooth the lines. After separating them, I marked the ply pieces with the former placement lines using the top view to locate them. Then, I made cutouts to lighten the ply pieces. After securing the two ply pieces together, I used a forstner bit to drill out the corners of the “holes” and a saber saw with a plywood blade to make the cutouts (Note that the area that supports the engine pod “pylon” has no cutout for more strength). That gave me a nice rounded corner look…not laser cut perfect, but then, this is a scratch build, not an ARF. The next step will be to glue the ply and balsa sheets together.

I bought a 2’ x 4’ ceiling tile to use as a “pin board”. I’ll cut 3/8” x 3/8” pieces of balsa from the block I bought and pin them to the overhead outline perpendicular to the sides to align the formers with perfect 90 degree angles to the sides. My next step is to make the pylon so I can fit the formers that hold it in place so there is no “play” in the slots where the pylon fits down into the fuse. BTW, the pylon will be removable if I need to take it off for any reason.

Here’s the link to my WEB site page with the pics.
http://www.thesquidget.com/seaplane.html

Check back in a few days to see what progress I’ve made.

cracker39

I've glued the ply and balsa side pieces and waiting for the glue to set. Then, I started assembling the engine pod "pylon". Tomorrow, I'll have pics of those two steps.

cracker39

Top and bottom side edge angles.

With the unique shape of the fuse, wider at the bottom than the top, there are angles to consider in order to give the top and bottom balsa a flat surface for glueing. I made a sanding block to do the job and the latest picture on the build site shows how to make it and the end results of using it. I needed balsa block for my nose piece, and the smallest size I could buy was way more than I needed, I used it for my sanding block as it’s easy to cut and accepts pins to hold the paper in place.

Once the sand paper is pinned in place, the larger flat side is placed on the side with the sandpaper on the edge as shown in diagram A of the pic. Sanding the balsa side was easy as the wood is soft. The Ply side is much harder. I took a chance and used my power random orbital sander on it’s lowest setting, holding it at the approximate angle to CAREFULLY sand the initial angle into the ply and balsa. Then, I used the block to fine sand to the exact angle. I used 100 grit sandpaper.

Figure A shows a diagram of the block dimensions. The small cutout (inner 90 degree angle) allows the sandpaper to extend past the edge of the side making sure that it is sanded flat. Figures B and C show the block without and with sandpaper attached. Figure D shows the resulting angles on the nose of one side. CAUTION. Make sure you cut the correct angles on the side. Ply side up, you are sanding the bottom edge. Balsa side up you sanding the top edge. When sanding the ply side, putting the pieces that you cut out back in place gives you a flat surface for the block to slide on.

Engine Support Pylon.

I used epoxy to glue up one side’s balsa and ply, and gorilla glue on the other. I used epoxy to glue the carbon fiber rods in place and gorilla glue to make the final assembly, although epoxy would have worked just as well.

In the picture, A shows the two halves after glueing the balsa spacers to the ply sides. B shows the same two pieces with the servo extension in place. C shows a closeup of the carbon fiber rod glued into the corner of the balsa/ply joint. D and E show the right and left sides of the completed pylon with the servo extension sticking out. It doesn’t really matter which side the extension exit at the bottom. The reason for the slot, rather than a hole like at the top, the connector must be directly under the bottom of the pylon to slip into the slot in the top of the fuse, then it can be pulled out of the slot to reach the receiver. It’s hard to see in the picture, but I sanded a 45 degree angle into the edges of the ply pieces on the front for aerodynamics.

http://www.thesquidget.com/seaplane.html

cracker39

That’s enough for one day. I posted these new pics on the build site.

Build jigs. I’m big on making jigs to help keep things straight (or curved if necessary). The pic SP8 on the build site shows one side on the overhead printout. I pinned two pieces of balsa on the board to hold the outside bottom edge of the side. I made an inside support “Tee” centered to rest the top edge against at the proper angle. This allows me to create the pylon formers to fit.

Engine Pod Pylon Formers. Pic SP9 shows the pylon formers with balsa pieces glued in to hold the pylon straight up. I glued a piece of lite ply to the bottom as additional support as the bottom of the fuse will be 1/8” balsa. The pieces that hold the pylon in place look heavy, but they are extremely light in weight. And, I cut “lightening” holes where I can. Pic SP9 shows the completed former set with the pylon in place. Later, a 3/8” hole will be drilled through the fuse and the pylon for the wing hold-down dowel to accept rubber bands. This dowel will pass through the solid rear half of the pylon, holding it in place. Simply removing the dowel will allow the pylon to be removed.

First Fuse Assembly Step. Pic SP11 shows the two sides being glued to the pylon formers. The piece of balsa resting on the tail end of the fuse is to eye-ball the level of the two side pieces at the rear. And with that done, I quit for the day.

http://www.thesquidget.com/seaplane.html

cracker39

It’s starting to look like an airplane rather than a jumble of pieces of wood. I didn’t plan on doing it quite this fast, but when you’re retired and it’s too hot out to do yard work, what else is there to do (don’t answer that).

Late last night I did a little more work on the formers, and today, I got them all cut and installed. I sill have to glue in some small pieces at the top and bottoms of the formers that are not perfectly flush with the sides. Those pieces are to provide a good flat surface for the top and bottom balsa to attach to.

Since I am using 1/8” balsa for the top and bottom skins, I made a keel piece for the front as I think that area will take some beating on landing. The keel should help it keep it’s shape and not flex too much. I won’t know if I’ll need a removable hatch in front of the “windshield” until I can check the CG. If it’s tail heavy I’ll put the battery in front with the hatch on top to get to it.

I guess I’m almost done for now as I don’t have the engine yet, or money in my hobby account to buy one right now. I could start on the engine pod (nacelle??) but I need the engine to finish it and to check the CG, so, I’ll probably put it to rest soon until I have the engine to work with. The engine I have is probably about the same weight as one I’ll buy, so I could get an idea of the CG using one of my existing engines taped in place in the pod.

http://www.thesquidget.com/seaplane.html

cracker39

Despite what I said in my last post, I started working with it again this morning. I’ve decided to go ahead and skin the bottom and leave just the top open to work with the control rods to the tail and a possible hatch on the front. To provide enough area for the glue to join the sheet to the frame, I added some light balsa pieces to formers so that there is plenty of wood to glue the cover to. Pic SP15 shows some of these areas.

I want to start on the engine pod, but haven’t made up my mind whether to use an 8 oz fuel tank that I have or get another 11 oz like in my other two planes. The smaller one should provide 8-10 minutes flying time, whereas the larger one gives me at least 15 minutes with the Alpha trainer. This plane will probably be heavier than the alpha and use more fuel to keep it flying.

http://www.thesquidget.com/seaplane.html

cracker39

End of the day. I got the bottom skin on today (see pic SP16 on the build site). It is all 1/8” balsa. The inside curve at the rear was a challenge for 1/8” thick balsa and 1/16” would have curved easier. But, to make the curve easier, I kerfed the balsa. Kerfing is cutting across the wood in the curve area, slicing about half way through, but careful not to cut too deep. This allows the wood to curve as the cuts open wider. However, this weakens the wood at that point, so after the piece was glued down securely, I ran CA into the cuts to make the wood more solid. I cut all of the pieces slightly oversize to glue on, then sanded the balsa’s edges flush with the sides and formers.

http://www.thesquidget.com/seaplane.html

fledermaus

I can see that even though you are new to RC you are definitely skilled at woodworking and drafting! Congrats on a nice project and for having the courage to experiment.

The only thing I wonder about is your engine pylon. Most of the pylon flying boats I've seen have used solid plywood for the pylon, and I am not confident that your 1/8 ply:1/4 balsa:1/8 ply structure will be rigid enough in torsion. You don't want your engine's thrust line wobbling about as you apply G-forces in turns etc.

cracker39

Good point about twisting. That's something I didn't think about. I can twist it a tiny bit with my hands, but it takes a lot of strength to do it. And, that's twisting the entire 12" length. However, the bottom 6" will be in a solid box in the fuse, and the top 3 inches will be in a solid box in the engine pod. That leaves only 3" exposed that can twist, so I don't think that will be a problem. I'll put a piece of lite ply around it at the top, under the balsa fairing piece to add to the rigidity.

Now, build news. I couldn’t wait for final assembly to see how it will look, so I mocked up the fuse with the wing and tail feathers (no cutouts yet in those). Now, for your opinions about the vertical stabilizer. Is there enough of it? It isn’t as high as I thought it would be, but it’s wide (front to back) and there’s plenty of rudder. New pics SPk17 and SP18 show front and rear quarter shots.

http://www.thesquidget.com/seaplane.html

sharpshooter223

maybe you should make it a little wider(extend the trailing end more towards the trailing end of the wing). maybe even give it a little curve just for added design.

cracker39

I didn't want to completely rebuild the vert stab, so I just made the part of the rudder in the water a little bigger. I cut out a lot of balsa and added some stringers to lighten the weight of the vertical and horizontal stabilizers, rudder, and elevator (and posted the pic on the website). The forstner bits don't cut balsa very well...they tear the edges somewhat, especially on the bottom, but with the covering, you won't see it

http://www.thesquidget.com/seaplane.html

cracker39

Today, I worked on the floats. I’m just guessing at the height for now as I don’t know how low the fuse will sit in the water. So, I’m not gluing in the support pylon yet as I may need to make a longer one. Other seaplanes I’ve seen place the wing float anywhere from mid-wing to the wing tip. I decided on about 60% of the distance from fuse to tip. The float is angled like most I’ve seen to just skim the water, not dig in.

Pic SP20 shows top and bottom views before putting on the top and bottom skins. SP21 shows the wing “socket” where the pylon is inserted and glued in place. I reinforced the rib that the socket is attached to. The socket it self is two 1/8” lite ply ribs with 1/4” balsa spacers. Notice the slots cut in the tops of the ply ribs. That is where I glued in a piece of lite ply as a seat for the top of the pylon (SP22). SP23 shows two views of the float “attached” to the wing. Pic SP24 shows the completed float.

http://www.thesquidget.com/seaplane.html

cracker39

For what it's worth, today I spent most of the day creating new web pages for my build on my personal web site. Why? As there are more and more photos added, those of you following the build have to scroll through all you've seen before to get to the new ones. The new site is my RC flying site. It has pictures and information other than the seaplane build, and the seaplane part will have separate pages for the different build phases. You can jump to the latest phase to view the new pictures without haveing to view all of the old ones again. When it's ready (two or theree days?), I'll post the new link and put a redirect link on the original site. The link to the new RC Flying page is;

http://web.tampabay.rr.com/wdsummers/********.html

Or, you can go directly to the new seaplane build project at:

http://web.tampabay.rr.com/wdsummers/seaplane.html

Be sure to change you bookmark if you have one.
__________________

cracker39

If anyone tried the new web pages and found problems, please let me know. I did find that the color scheme page was missing and the wing float page link to the color scheme page just went back to the float page and I fixed that as well. Any other problems can be reported to me...thanks.

cracker39

I finally covered something with the cub yellow ultracote...the wing floats. Now you can see one of the colors I'll be using. Here's the link to the float page.

http://web.tampabay.rr.com/wdsummers/floats.html

fledermaus

I see that you have kept things very simple, and you are using a flat bottom on both the fuselage and the wing floats. I think you may find problems during taxiing and take-off because the plane will "skate" sideways on the water in any degree of crosswind.

Floats and flying boats usually try to have a V-shaped bottom, to give some degree of lateral "bite". It helps the plane to track in a straight line as it moves across the water.

cracker39

I made a little more progress today. I made the wing fairing for the top of the fuse and installed it and the windscreen. I'm still leaving the front top open until I know if I need to make a front hatch or not.

I also covered the tail feathers with the Cub Yellow. After I've bought the dark blue, I'll put on the accent stripes. I guess I'll go ahead and cover the wing soon.

cracker39

Yep, the flat bottom may cause some problems, but trying to build a v-bottom seemed too complicated for me. In the middle of a big lake, I should have room to get it down into the wind.

I began work on the engine pod today. That's a tedious job, working in a small compartment, but I think it will turn out fine. So, a new page has been added to the ******** pages.

fledermaus

Actually, a V-bottom isn't difficult to make at all. You don't have to make it with a fancy curve, although that can be done without too much trouble. When I scratch-built my floats, I put in a V-shaped hull bottom just by making the centre keel deeper than the sides. Then, the hull bottom was made with flat balsa panels (grain across the long axis of the hull and wide enough to span from rib to rib), one on each side of the keel.

Getting it down into the wind isn't the issue, it's bringing it back after it touches down.

cracker39

I suppose that trial and error will tell me if the flat bottom is a bad mistake. I also suppose that if it is, I could cut out most of the front bottom panel and rebuild it as a vee bottom.

If you read this post earlier today, I've edited it. I finished the engine pod except for the four screws that will attach the top hatch to the pod and possibly adding some accent stripes to the sides. The pylon is permanently epoxied into the pod. It will be removable from the fuse if necessary. My plan at the moment is to drill the front wing hold-down dowel hole completely through the rear of the pylon and use the dowel to lock the pylon in place in the fuse. The engine pod page has more pics added.

http://web.tampabay.rr.com/wdsummers/pod.html

cracker39

WORST FEARS PUT TO REST!!!

Since the beginning of this project, I've been anxious about getting the CG right on this model, since I was guestimating the wing placement. Today, I used masking tape to attach the ailerons to the wings, then the wing to the fuse since I don't have the dowel holes drilled yet. I put the engine in the mount on the pod, and taped the muffler to it and put the pod in it's socket. Finally, I put the tail feathers in place, placed the top pieces of balsa where they will be attached and laid my goldenrod pieces on top of the fuse. I rigged up a CG balancer and tried it out. I was so relieved to find that my expectations were ON THE MARK...it was just slightly tail heavy as I thought it might be. With the battery in the front, just before the pod pylon, the CG was dead on using the CG marks I made (back 1/4 of the wing chord, 2 7/8", from the leading edge). this was without the tank inplace, but it's directly over the CG mark and would have made very little difference in the balance. So, I will have a removable hatch cover in front to access the battery and will probably have to use an extension to reach the receiver which will be behind the pylon so that the tail servo connectors can reach it.

cracker39

Sometimes I think that less is best. I put the red and blue accent stripes on my tail feathers yesterday, and I changed them to be narrower than pictured on my build site. And, I did change the lines on the side to join at the point of the nose.

Here are 3 pics. First, my original scheme, second, my new striping scheme, third, new side color design

cracker39

I'm nearing final assembly. I finished covering the wings and fuse top and sides and painted it's bottom section (pics posted). I'm attaching the ailerons and the elevator this afternoon. I can't attach the rudder until it is in place on the fuse. I got some epoxy in my aileron hinges (the nylon and pin type), but a drop of machine oil on the pins loosened them up. I'm using CA hinges on the elevator (6) and rudder (3).

I should have my Hitec Supreme IIS receiver by Saturday and can test and hook up the servos. While I was finishing up the covering on the fuse, I finally noticed that my two rolls of cub yellow didn't appear to be the same color at all. One roll looks more like bright yellow, although I'd swear that both were labeled cub yellow. As it is, only the tail feathers are in the darker (actual) cub yellow. The wing and fuse are both the same shade. It's an interesting color difference, but not a big deal as far as I'm concerned. (Yeah, RIGHT...I'm a perfectionist and this ruined my streak.)

I'm starting a final assembly web page which I'll put online in a day or two or whenever I have something to show.

cracker39

It looks like I might solo with the seaplane before I solo with my Alpha trainer. Today, I made 1 ½ successful landings. The first was textbook. Nice glide in and flared it just at the right time for a nice soft touchdown with no bounce. The 2nd was looking good, but I went a little too far and it tilted to the right and as I applied a little left aileron, it was on the ground without enough flare and the prop hit some grass and broke. That’s the 3rd one I’ve broken…two on bad landings and one from my crash. I’m going broke $2.49 at a time. After breaking the 3-blade prop, all I had to put on was a 2-blade 11-6 and it had more thrust and my trainer wanted to bank right hard. We had to apply full left trim to get it to go straight. Then, it also wanted to climb hard at ¾ throttle and we had to keep the revs down. It made me nervous and I said no more until I get a 3-blade prop back on it.

BUT, it’s given me enough confidence that I’m willing to try the seaplane this week after I get my late arriving receiver. After all, I’ll have the entire lake to land in, not having to line up on a specific approach to hit a runway. And, we have hardly any wind at this time of the year until after 10AM and I plan to be out by 7am to try it.

I’m still willing to try out the seaplane, but CAREFULLY until I know it is trimmed out properly. Than, I may try to get it in the air. I’ll do some taxiing at first, lifting off just enough to check aileron and elevator trim. After the bad experience with that today, I want to make sure it flies straight hands off before I lift off for good.

cracker39

No flying it soon. I finally got my order from Tower and they sent a single conversion crystal, not a dual that I needed and I'm sure I clicked on the crystals available for the Hitec receiver I ordered. I had to return it today for the correct one. My other JR crystals won't fit in the Hitec receiver. I just hate it when a company makes things specific to just their own products.