F9C2 Sparrowhawk

Scotto

Elite member
The Sparrowhawk has the honor of being the only manned plane to be carried inside a zeppelin. (That I know of). The USS Akron and USS Macon zeppelins that carried them were among the biggest flying machines ever made. It is an absolutely fascinating history and marvel of engineering. There is a good history of them and much more here if you're interested.
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Anyway, I built this for buildruary, and it turned out pretty good so I've taken the time to make real plans. I'm planning on building another hopefully cleaner plane from these plans. I'm sure there will be things to change. One thing I know is missing is the main center section of the top wing spar. The first one works but wasn't very pretty. This is about 1/8 scale at 38 inch wingspan. The design is kind of a combination of a card paper Model and a baby blender with a lot of trial and error and a little help from the balsa plans on outerzone.
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Version 1
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Version 3
Resource page
 
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Scotto

Elite member
Yikes. I've been looking at this plan for a couple weeks and the day after I post them up I find some big problems.
OK almost a month later I think Ive got this mostly figured out.

20210330_231945.jpg If you print full size with free version adobe acrobat and click poster and cut marks, it gives you little X's in the corners. Then you can line up the edges and pin the x's and I just use a glue stick and almost no tape.
20210331_223848.jpg I'm trying something a little different here on the wingtips. Mixed results but I peeled the paper back part way and left it until the fold over was all done and then glued it back for some rigidity. I tried glue stick, hot glue, and spray glue. I think spray glue on the inside and hot around the edge worked best.
20210401_010729.jpg The spar is kinda laminated I guess you could say. I used 1/8 inch balsa on the front because its what I had. The gull in the top wings was the hardest part for me to get right, but its probly my favorite detail in the look of the plane.
20210401_014833.jpg 20210411_204415.jpg I forgot to glue in the servo on the right side before I folded it, but it wasn't a big deal. Its probly better than the other side. The TE is intentionally not supposed to touch the table because I read somewhere that the F9C had a Clark YH airfoil, which is basically only different from the Y because of the "relief" at the TE. It is suppose to help stability with being so short coupled and all.
20210401_024656.jpg Before glueing anything on the fuse I had to shave a little on the mounting parts of the top wing for it to sit level. Then I glued some pieces to lock the sides square. The top wing is supposed to have some positive incidence and the stab and lower wing is flat. I read somewhere that it makes the stall characteristics better. So that's built in to the mounting pieces with the tabs.
20210403_030008.jpg This part went pretty smooth. Just had to shave a little to get the tail pieces square. The front formers weren't glued yet. I glued the wingtips on first and then peeled and everything. After the bottom wing is all glued in the little tabs behind it are just in the way of the skin.
20210403_030144.jpg Then the top wing was ready to go on after double checking the tips both measuring the same from the table.
20210403_235230.jpg Would be scrap pieces tacked on just to have something to glue the skin to later.
20210404_005437.jpg This piece the paper is off the bottom and it has a little crease down the middle and on either side.
20210404_015356.jpg Ooooo ya. My favorite part. There could maybe stand to be a bit more paper. I would suggest glueing the front first lightly, then after its set do all but the very back. Then do the front and back hotter with more glue and pinch it to more of a taper. The paper on the inside doesn't need any glue really. The only place I tried to get it, it wrinkled.
20210407_225536.jpg It seemed a little weak to push with a screwdriver so I put a tiny piece of wood to help.
20210407_225624.jpg On version one I realized the battery and esc was getting pretty warm so I cut some vent holes in the front. It might be good to do the skewers first and make them longer than normal. Like 4-5 inches maybe. I also braced them up in the front with the little eyebrow wax sticks I stole from my wife.
 
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Scotto

Elite member
The skin is printed directly on 60# "cover" 8.5x11. I'm no Dwight Schrute, I just guessed by looking at the thickness in thousands. The test pieces I weighed were about 60% the weight of DTFB with one side paper peeled. So it has some benefits. Hopefully it takes paint well. Just cant grab the plane by the fuse like normal, but the skyhook will be sweet to carry it by.:cool:
20210411_204025.jpg Next I did the rear skin. It took a lot of trial and error but it eventually fit. Before I glued it I traced it, scanned it, and traced it digitally in inkscape. I left tabs to pull it snug till the glue sets and cut them off. Then I whittled the end of the fuse more rounded.
20210409_015544.jpg Ya I don't like this but Ill make the best of what I got here. Before cutting it out I rolled it against the table edge. To glue the slit it needs to be upside down. I pinched and marked it. I didn't tape the inside but it could help. Theyre mirrored so it doesnt matter except for the green lines for scale paint job.
20210410_024909.jpg The bottom with the tab to pull snug onto glue. The hole is to help getting the power pod installed.
20210411_204743.jpg Maker foam looks better for sure. Kinda forgot the control rods. Also forgot to put wooden donuts to beef up the swappable skewer hole. I got all my piano wire on Grainger BTW. Don't ever buy it coiled up in a roll to save a few bucks. It's practically impossible to straighten. o_O:cautious: Also kinda dangerous. But the rods are a pretty good value I guess, just not chromed, and you have to get your own z bend pliers.
20210410_235840.jpg My inaccuracy in bending and foam cutting had to be made up for in glue and a jig. The blocks are 4" tall. There is a skewer in the foam well of this in the middle of the wire. If that make any sense.
20210411_011045.jpg After it was centered up I reinforced it with the eyebrow wax sticks. There is a little square that goes in front of this bottom piece. 20210410_025428.jpg This is quart size paint stick. The wire will slide in sideways first. Then glue on the bottom piece with wires before glueing this main wire and stick. Actually I could have snuck the skin on to the wire and not had to slit it.
20210412_001958.jpg I'd love to take credit for this piece, but it all goes to Roman Vasilyev, der Kampfflieger, https://kampfflieger.ecwid.com .Leave some tabs to glue to and extra to fold back to glue to the "engine". I should have made the center hole bigger and not cut each sliver up so far. I changed it for the plans.
20210414_021313.jpg Same story with the wheel pants. All I did was cut an "A" style fold in it and peeled inside paper. Works really good especially for scaling up x6.
20210417_014650.jpg Version 1 looked a little too big so I shrunk it in inkscape. I wisk I would have painted the parts before glueing them together. The plan is to pin it with a few short sticks and a little velcro. Motor pod mount came out a little too high. Changed it in the plans hopefully for the better.
20210419_000555.jpg I kinda struggled with the fairing or whatever its called. In hindsight the back of it is too high, but my patience was running low.
20210419_020829.jpg I sliced this longways and speared it so it could slip over the big wire. Alot of glue hopefully they will hold the pants.
 
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Scotto

Elite member
Following this, looks nice.
Thanks. Sorry Ive been abusing the edit button, quietly updating my progress. I thought Id put the build all organized in one place. (I should just do that with my tools instead).
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Almost done. The wheels and pants arent attached. Needs the skyhook and control rods. Maybe a tailwheel. I keep finding things I dont like. The first engine/cowl was 5 3/4 and that looked too big. This one is 5 1/4 and looks too small. Something doesnt look right with the front former. And I got distracted by the center of the top wings and never checked the span- 1 1/2" too small. I also dont like the fairing or whatever on the bottom wing and looking at pictures of the real plane it barely has any at all. The next one will be better and go together alot faster too because of the plans. I will share the plans soon. Unless I start over with this 3 view I just found.:unsure::p
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