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Nov 27, 2020, 05:12 PM
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D-Rock's Avatar
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Build Log

Park-flyer "Fun Scale" FW-190 at 27”


Stick and tissue designs have been a focus of mine for several years. Starting way back in 2007, my first design into this style was a 30” I-16 Rata. I then moved up into the 60” range and all the way up to 80” with my Me-109 (and then back down to 60” for several others). But with a nice open park near me, I wanted to get back to the smaller size. I had drawn the parts for a Comet Speed-Matic Fw-190 free flight model that has a wingspan of 18”; and it did build quickly. The benefit of this sized model is that I didn’t need to go out to the garage to build, but it could be done on a card table while I watched TV. After quickly framing the model up, I was able to reacquaint myself to covering in light weight tissue again. With the success of the free flight model, thoughts turned to going a little bigger for park flying RC. The enlarging of the design required quite a bit of redesign- both to provide for the RC, but also some corrections and changes to strengthen the design. In the end, I would describe the model as a “Comet inspired” version of a Fw-190- spanning 27”.

Lightweight was always a focus for the model, so I am using some lightweight “standard” equipment- in that the rec, power unit, and servos use the conventional connectors and is not the sub-micro linear types. The servos are 4.3 grams (4 used) and the motor is 18 grams with a 7 amp esc. But enough with the prologue, lets get to gluing balsa!

I like to start with the tail feathers first. The primary wood used in the model is 3/32” balsa- both in strips and stringers. The horizontal only has 2 pre-cut parts, the rest is 3/32” cut to shape. The elevators are built solid with the horizontal and then cut free. A 1/32” diameter piano wire “U” will connect them together. The vertical is similar with the rudder cut free after the construction.

The fuse is built in halves with a keel- just like a Comet or Guillow’s model. The left-hand formers were added and then the 3/32” square stringers. An additional former was added for the rear of the wing. I also used this to help add the wing fillet for later. The firewall is from 1/8” lite ply- lightweight yet strong enough for the small motor. Once the left half of the fuse was complete, it was unpinned from the board and the other half added. The model features a “built-up” canopy and stringers are used to create the shape. The upper most stringer (either side of the keel” I used Windex to allow me to add a slight bend/curve to match the canopy shape. The hatch formers and rails were added- these were then sanded to blended to match the fuse contour before being cut free. Magnets will hold this in place later. Work on the wing will be next.

D-Rock
Last edited by D-Rock; Nov 27, 2020 at 05:22 PM.
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Nov 27, 2020, 08:41 PM
Big gov never Works
St. Martin's Avatar
Cool, Derek! I wonder if the 3/4"scale Guillows canopy would fit?

Fuzz
Nov 28, 2020, 07:28 AM
Wanted for breaking Ohm's Law
Dennis Sumner's Avatar
D,

I’m going to follow along after my ME-109 build. Small models are a lot of fun to build and fly!

Denny
Latest blog entry: RC Throw Gauge
Nov 28, 2020, 09:26 AM
Still the "Pro"-crastinator...
Steve85's Avatar
I always enjoy your builds, and there's something carefree about small models. Looks like a great start.

Steve
Nov 28, 2020, 03:16 PM
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D-Rock's Avatar
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Thanks guys, these smaller projects go together pretty quickly and are also very economical. Work on the wing was next. The leading edge is from 1/4” balsa cut to height and the trailing edge is 3/32” x .3”. An additional update was to use a more “RC” friendly airfoil. The original had a very sharp leading edge- very similar to that on the Guillow’s models. With the lessons learned from my RC Guillow’s P-40, I updated the 190’s to be more rounded- more of a Clark-Y type. Stringers were added from 3/32” sqr. balsa. The spar that the aileron hinges into is 3/32” sqr. top and bottom- once the aileron was cut free the space between these two stringers was filled with scrap balsa. Part of the ribs behind the spar were cut free to allow for the 3/32” balsa sheet aileron leading edge. I used a pin as a spacer between the spar and the aileron leading edge to allow for the hinge. Each panel was built separately. Once they were removed from the board, I used masking tape to protect the ribs while I contoured the leading edge. This was initially done with my small plane, and then finalized with a sanding block.

I had initially planned on using torque rods with a 9-gram servo in one for the root bays but decided on using separate servos for each aileron. The ones I chose are 4.3 grams each, so it really didn’t cost me any noticeable weight increase. Rib W4 was notched out and a 1/16” plate was added under the servo. Since replacing/removing the servo would be major surgery once the model was finished, I chose not to mount with screws and just glued them in place. Prior to doing this I tested them to make sure they were working properly and “centered” with the horn to be 90 degrees with the bottom of the wing. Then with the power off, I gently turned the horn to be flush with the wing to allow for covering. The ailerons were hinged with 1/2” x 1/4” “CA hinges”- I have a sheet that I cut to size.

D-Rock
Nov 30, 2020, 11:50 PM
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Work continued on the wings. I added 1/16” balsa in-fill just inside of W2- this will allow a greater surface for wing mounting. With one panel elevated, I glued the two together using Titebond wood glue. I also created the mounts for the elevator and rudder servos (both 4.3 grams)- these are mounted to the front of F5. The hatch was cut free and scrap 1/16” balsa- cross grained- was glued on top of the side longeron between F3 and F5. This will be the rec and battery mounting plate.

I also decided that I wanted to be able to “display” the model on her feet, so I worked on some plug-in gear. The main gear was made from square brass tube, some round tube, and some 1/16” piano wire. The large square tube is .14 in outer dimension and the smaller is .11- this will slide into the larger tube. There is a short section of round tube the slides over the wire strut and then this is slid into the smaller square tube. I cemented this all together with JB Weld, adding a small retainer washer. The large square tube was blocked in with scrap onto a flat sheet of 1/16” and this was glued to the forward stringers. The strut assembly slides into the larger tube and is good for static purposes. I used Guillow’s 1.75” plastic wheels and an extra EZ connector bottom to retain them. The tail wheel area was blocked in with sheet and piano wire was wrapped around the balsa tail wheel parts. This plugs into the balsa block and tension keeps it in place.

D-Rock
Dec 01, 2020, 03:24 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Veey good D Rock. I built the Al Lidberg TA152H from his kit. It sounds as if your 190 is about the same scale (1/15th?). It flew really well but much better when I trimmed the wings back to "C" span. A really great model. Will you be kitting this one?
Dec 01, 2020, 09:59 AM
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AntiArf's Avatar
Looks good Derek. I see someone who knows how to mount aileron servos in small models. (my method) I can count the failures so far (zero) so I haven't found the need for heavy ply plates and removable access covers.
Dec 03, 2020, 09:24 PM
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Thanks guys, I do plan to offer this one once the design is finalized. The next sub-project for the model was the spinner. I decided to try and make one from balsa and this would slip over the “coned” prop nut. Using multiple layered circles with the centers cut out to fit over the prop nut, I glued them together like a layer cake. I then used a lit ply back-plate and mounted it in the spindle of a cut off wheel (with the cutoff wheel removed). This was then tack-glued to the back of the spinner “stack”. I placed it in a drill and mounted the drill in a vise. With the rotation moving “down” (to reduce risk of kick-back) I held a sanding block to the spinning assembly to smooth it all out. Overall, I think it turned out pretty good. I plan on gluing it directly to the coned nut with perhaps canopy glue.

Its at this point before covering that I like to place the model all together to see how she looks. Here are a few shots of her in the bones. Next will be the covering and I have a few fun things planned on how to do that.

D-Rock
Dec 04, 2020, 03:25 AM
Big gov never Works
St. Martin's Avatar
You have captured the look, Derek! It's nice to see scale airplanes, and not hiding the beauty of a model plane.

Fuzz
Dec 05, 2020, 08:33 PM
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Printed covering


Covering the model was the next main step. On my Guillow’s inspired P-40, I had initially tried my hand at printing directly onto the tissue. This worked pretty well and I thought I’d do some further testing on the 190 so that I would be better prepared when I cover the Nate. There are some good how-tos out there but the best I found was on Paul Bradley’s site: http://www.parmodels.com/home.html -look under “techniques and references”. Based on the information he provided here is how I did the covering.

Design: I needed to decide on which paint scheme I wanted to do, and since the we have two schnauzers, I thought it would be fun to do “Old Shap” flown by Josef Heinzeller which featured a schnauzer on the nose. I then used brown masking paper to make templates for the covering. Since the model would need to be covered in sections (fuse used 4-5 itself), each of these needed to be created in CAD from the paper patterns. I do my CAD in 2-D but if you design in 3-D there is probably a tool you can use to “flatten” each section to give you the correct shape. One I had the templates in CAD, I added the panel lines and the overall camo scheme. Each CAD program is a little different, but I use TurboCAD. I found the order of layers is important. I actually needed to add the color first to the template and then overlay any additional lines for alignment or for panels. Each of the sections was laid out onto a legal “sheet” for printing.

Printing and sealing: All of the research I found said to use ink-jet printers and that is what I did as well. My printer is a cheap HP color printer that can print up to 14” legal sheets. You need to attach the tissue (I used light weight silk span- same type that comes with Guillow’s models- white in color) to a blank sheet of paper. To do this I used spray adhesive- but you need just a very light- and I mean light- coat onto the paper sheet. I then placed the tissue over the top and pressed out any wrinkles with my hands and then cut tissue to the same size as the paper- with the exception of a 1/4” overhang at the top- this was to make it easier to pull the tissue off later. Its best to do a practice print so you know which is the top of the sheet and how close the boarders are (even when set to border-less) to the sheet edge. I only have the one sheet loaded in the printer and print each page one at a time. I did not have any jamming issues when using this the spray technique. I tried taping the tissue on and this did not work for me. Once the sheet has printed, give it a couple of minutes for the ink to dry. You next need to seal the ink so it has less of a chance to run or smear when applying. For this I used Krylon K01303007 Acrylic Spray Paint Crystal Clear in 11-Ounce Aerosol- you can get this at most craft and hardware stores. I applied several light misting coats- don’t let it get too thick or wet. Let this dry and then you are ready for application.

Application: I found that when removing the tissue from the paper, the best technique it to pull it back over itself in a steady pull. This can make the tissue “curl” and you can gently pull it over a corner to help straighten it out. I used a glue stick on the “outside” frames of the section I was covering. I did the vertical first. Try and pull any wrinkles out during this stage, the glued stick does allow for some movement and adjustments. Once satisfied I then sealed the edges with thinned EZ dope. I let this dry for an hour or so. I then shrank the tissue using a very fine mist of water. I actually sprayed “up” at the part to avoid any large water droplets hitting. I then aided drying by using a heat gun gently over the part. Once this was complete, I then sprayed the section/part with the Krylon with several more coats, a little heavier each time. This was the final “sealing” coat and eliminated the need to coat the whole surface with EZ dope to seal it.

The fuse was covered once the tail and hatch were done. The bottom was first applied. From the picture you can see small location marks that really helped with alignment. Then the rear side sections of the fuse were applied. On the first panel half, overhang on the top and bottom is not a concern, but you need to be accurate with your “trim” of the second half to be sure it stops at the edge of the keel. The forward sections were then added. You can see from the pics these were a “T” shape and were the full height of each side. If I were to do it over again I would have made top and bottom pieces for this area.

The wings were pretty straight forward with one exception- I covered the wings with the ailerons in place. This allowed me to “build-in” washout when adding the top covering. I used a pin to hold them in place while attaching the bottom covering. Then the pin was removed, and the top covering was added. I had shimmed the rear outer rib up with a 3/32” scrap so the washout was held when applying the top covering and not just when it was shrunk. This worked really well and then the tissue was cut freeing the ailerons. The excess tissue was then glued to the aileron leading edge. I had printed separate sections for the aileron leading edge but these were not needed.

The wing was then glued to the fuse and a small section of balsa was added to finish the front wing saddle and this was also then covered. The pilot is a profile picture glued to some scrap balsa and the armor plate was made from cardstock. The front of the cowl was done the same way with printed tissue from paper templates.

D-Rock
Dec 05, 2020, 08:48 PM
Or current resident
glewis's Avatar
Wow! I'm impressed with your results using HP inks. Looks great and I love the traditional model airplane look.
I tried that technique on Bradley's website and couldn't shrink printed tissue without the ink bleeding. Once I added enough clear to prevent bleeding it wouldn't shrink. You seem to have found the perfect balance.
Dec 05, 2020, 11:18 PM
Paul Kohlmann
Longhorne's Avatar
Agreed! That looks super light.

Now I'm tempted to do another tissue job.

Koh
Dec 06, 2020, 12:23 AM
Big gov never Works
St. Martin's Avatar
That looks great, Derek!
Dec 06, 2020, 09:34 AM
Still the "Pro"-crastinator...
Steve85's Avatar
Very nice. I covered an old Guillow's Rumpler using the same technique and it turned out quite well. Sadly, my inkjet printer died and now I have a laser...

Steve


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