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Apr 11, 2016, 12:51 PM
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Build Log

PZ FW-190A Rebuild and Flap Installation


Several weeks ago, I screwed up and let my FW slip behind a scope of trees when turning onto final. I tried to straighten my wings and climb out. Unfortunately, I was too low and too slow, and she augered in, destroying the wings. The fuse, motor, and all electronics survived. So, I bought a replacement wing. I had intended to install split flaps on the FW, and figured that this was the perfect time to do it. There has been quite a bit of interest in Flap mods in the PZ FW-190A forum; so, I thought I'd do a build log. I'm a day into the build, but should have enough photos to fully document what I have done.

For those interested, here's the link to the Crash Investigation Report that I filed in the FW-190A Forum (Post 5214): https://www.rcgroups.com/forums/show...92862&page=348

I've also posted a couple crash scene photos.

The wing is really wrecked much worse than it appears in the photos. There's a possibility that I could put it back together, and I've saved all of the pieces (except the left aileron, which was not recovered); but, for now I've decided to go with a new wing.
Last edited by Oxotnik; Apr 11, 2016 at 03:09 PM.
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Apr 11, 2016, 01:37 PM
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I purchased my replacement PZ wing from MotionRC. The wing came painted. Not included were servos and control horns and linkages, gear, and the fuel tank release mechanism. The plastic wheel well was included, which made me happy (I was afraid that it may not be included). The photo from MotionRC shows control arms and linkages, but they were not included.

On my original FW, the plastic wheel wells and the wing attachment piece were bonded onto painted foam, and were easily broken. With a little tugging, theses pieces on this kit seem to be bonded better! Hallelujah!
Last edited by Oxotnik; Apr 11, 2016 at 01:59 PM.
Apr 11, 2016, 02:15 PM
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Since I had a broken wing, I decided to practice on it. I'm glad that I did, because after cutting the servo well, I discovered that the servo wires would have to jump the wing spar. So, on my 'real' wing, I'll put the servos on the same side of the spar as the aile and gear servos.

There is a panel line for the forward edge of the flap, but no line marking its end, nearest the fuselage. I decided to make the edge at the start of the curve where the wing molds into the fuselage.

I decided to use a blade from a utility knife, unused of course, for cutting the foam. The flap is about 1.5" wide; so, about 3/4 of the blade would be needed to cut the foam for the flap.

I had intended to cut an even 1/8" off the bottom surface, but ended up going about 1/4" deep on the leading edge side. On the trails by edge, I cut ~1/8". With the supports, each flap is about 3/16" thick; so, the inner surface will have to beveled to be flush with the wing's TE.
Last edited by Oxotnik; Apr 11, 2016 at 02:40 PM.
Apr 11, 2016, 02:27 PM
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The flaps are cut from 1/16" aircraft-grade plywood, and I reenforced them with 1/8" balsa stringers. I used wood glue to bond the stringer supports to the PW. I used a T square to draw straight and perpendicular lines, and I cut the PW with a band saw. After cutting, I sanded the flaps' edges and surfaces with a band sander.

For each flap, I cut 2 stringers to run the length of the leading and trailing edges, and I cut 5 stringers to run front to back.
Last edited by Oxotnik; Apr 11, 2016 at 03:12 PM.
Apr 11, 2016, 03:06 PM
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Two steps forward, one step back...

After gluing the supports onto the flap, I noticed that one of the flaps had taken on a slight twist. When I had fit-checked the twisted flap on the wing, I decided that the twist was too much (almost an 1/8" difference, from one end to the other). I'm going to make a new one. Kurt Tank would never approve of this shoddy workmanship.
Apr 11, 2016, 03:13 PM
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Great engineering work and installation Oxotnik. When it comes to our hobby, precision must be maintained throughout the process. Interesting material you chose. The flaps installed on my FW 190, aluminium was used.
Apr 11, 2016, 03:22 PM
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Hmmm, I never considered aluminum. I debated between 1/8" and 1/16" plywood. I obviously chose the 1/16". With the supports, I believe that the flaps should be stiff enough <fingers crossed>.
Apr 11, 2016, 04:01 PM
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I'm in full agreement with you. The landing flaps will work as designed and be stiff once installed. Plus will be a bit less weight too.
Apr 11, 2016, 07:52 PM
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Plywood? Aluminum? Hi tech, hey? I used depron from WalMart chicken packets. Giggle!
Apr 11, 2016, 07:57 PM
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Retracts...


Same as with my previous wing, the retracts won't retract properly. The right wheel hangs up on the wheel wheel housing. Using the trusty #2 Xacto, I carved out an arc (~1/4" at its widest), all of the way to the base. Dabbed on a bit of polycrylic to seal the exposed foam, then covered that with Model Master 2036 (RLM76), which is a near perfect match for the licht blau belly of the FW.
Apr 11, 2016, 08:07 PM
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Quote:
Originally Posted by StangBanger
Plywood? Aluminum? Hi tech, hey? I used depron from WalMart chicken packets. Giggle!
LOL, Stang! We have chickens in our backyard. They're terrified of my planes, especially the quiet soaring planes that look like hawks. Maybe if they smelled the chicken, they'd think that the plane was one of their own... Not that any chicken can soar by any means.

I'd considered using foam... for about 2 seconds. Unfortunately my foam-shaping skills (even with a hot-wire cutter) suck... at best. I have the skills for plywood though. 😎
Apr 12, 2016, 08:31 AM
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I used plastruct styrene sheet, about 1.5mm thick, with two carbon fiber rods laterally for stiffness. I thunk I'll add foam ribs to make it lok more realistic. I hinge taped the whole length both inside and out to secure it. I'll post pics tonight when I get home.
Apr 12, 2016, 06:41 PM
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As I'm putting my FW back together, I'm starting to think about how I'm going to cover up the wire runs under the wing. I didn't want to buy the wing tape from PZ. Is there a type of tape that anyone recommends that'll stick well to foam (painted foam at that) and can be painted RLM76 light blue? Maybe a vinyl tape or something, like that used to make vinyl decals? Thoughts, recommendations?
Apr 12, 2016, 06:50 PM
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I use vinyl electrical tape a lot. It lays down easily, takes curves and angles and sticks nicely. Seal it over with WBPU and paint to match.
Apr 12, 2016, 08:14 PM
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Wbpu?


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