Orlik PBJ-1H Mitchell

Discussion in 'Aircraft & Aviation' started by Bomarc, Jan 26, 2010.

  1. Bomarc

    Bomarc Member

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    Thanks guys. Always a pleasure when you two drop in.

    Yes Elliot, in his early days, Elvis was known to visit the local aircraft plants around Memphis to practice his dance moves with landing gear struts. Years later, Sylvester Stallone would use this same idea for his "Rocky" movie, only there Rocky would visit the local meat packing plant in Philly and practice his punching on sides of beef! True story! Look it up....;)

    If you're referring to this loop (red arrow):

    [​IMG]

    ....it's the hydraulic line that supplies the outer brake drum. It snakes through the hollow axle to the inboard brake drum (blue arrow). Then in a "tee" connection moves up the strut into the nacelle:

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    I don't know if you're aware of it or not, but FYI, the center circular portion (brake assembly) of the wheel is stationary and fixed to the axle/strut assembly. The outer rim (with all the spoke holes) is the only part that actually rotates. This was the standard U.S. bomber wheel rim design, and was used in varying sizes on all the types in service in WWII, from the B-29 down to the A-26 Invader.

    I haven't added the brake line as of yet until I figure out how I'm going to fabricate the strut, but the extended hollow tube on my main wheels is part of the "master plan". Now if I only know what that master plan was.....:confused:

    Incidentally, the second above picture was taken by Dr. William Wolf for his book "B-25 Mitchell: The Ultimate Look" (Schiffer Pub.). Highly recommended, and one of my primary ref's in this odyssey.

    Mike
  2. Bomarc

    Bomarc Member

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    So I took a small diversion from the landing gear to the make the radio compass loop antenna otherwise known as the “football”. This was the last part on this model that I would make using the dremel tool/card stack trick, and since I just finished spinning up the tires and had all the stuff handy, I could make this fast, right? Well, this little unassuming part took way longer than I thought, mostly because I had no clue as to the standard size of the thing. Thanks to Mark (shrike), who supplied me with the basic dimensions from the NASM inventory, I could spin this thing up. I used the wood dowel as shaft routine:

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    Below it is the kits “football”. I built it up to see if I could get a size, glad I didn’t go with that. I used a lot of supper-glue for this assembly, gluing two layers of mat board for the mount, then filing and sanding to shape, and coating with super-glue again:

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    Once the shape was there, cut if off and added a wire core to help mount it:

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    Mixed up a color to match the off white of the bombers belly (a very “cream” shade):

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    And how it will look in it’s final resting place, tacked there to see if my color was a match:

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    Another classic “10 minute job” that stretched into a long afternoon. But with that diversion out of the way, I can resume our regularly scheduled program, already in progress….

    Mike
  3. Bomarc

    Bomarc Member

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    Started on the main struts. I’m going pure scratch on these as the kits parts are too rudimentary, and I’ve already started down this path with the rims/tires. Rolled two “cores” with a wire inside for strength:

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    Coated them with superglue after the fact as I wanted to get a smooth surface for this next bit. To make the shiny metal oleo strut, I first super-glued a section of tooling foil on:

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    Then (lightly) chucked it up and smoothed it down using those sanding sticks from Sally’s Beauty Supply, bought on a tip from Mark ("shrike"):

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    Then another spin with rubbing compound, followed by polishing compound:

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    Nice and shiny like the original:

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    Here’s the stuff I used. I can’t remember where I ordered this, I think it was Widget’s Tool Supply:

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    Spring Break is here, so that means travelling:

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    Yep, the PBJ show is on the road again, and may be coming to a town near you!! Check local listings for dates and times…..

    Mike
  4. stonefort

    stonefort New Member

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    Amazingly well done!
  5. Bomarc

    Bomarc Member

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    Thanks Stonefort. Being that was your first post here on Zealot, I appreciate it even more.

    Made a little progress on the main struts here at the undisclosed location in Southern New Jersey. Alas, my dad's camera, plus the available light where I work make for some poor images. But the following should make do until I'm back at home base.

    Using a quick series of sketches I made up from photos as a guide, making the struts involves nothing more than rolling tubes on top of more tubes. As things were built up, I would coat the whole with superglue. While I hate working with the stuff, I'm finding it increasingly useful, particularly for hardening the paper and smoothing joints, then sanding to shape. This is most useful when making the "ears" that the torque links hinge on:

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    All the components fabricated:

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    Then assembled:

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    Some final tweaking and and alignment corrections, then I'll disassemble again and paint all with aluminum enamel. After final reassembly I'll trim to length when it's time to mount in the nacelles. I'll add the brake lines later (forgot to bring the solder wire with me on the road).

    Better pics later.....

    Mike
  6. stonefort

    stonefort New Member

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    Mike,

    I built plastic models for a number of years and enjoyed adding details, but being new to card modeling, I'm amazed at the level of detail you're able to add with this medium. I'm still trying to recover some of my previous skills, but am looking forward to trying some of your techniques on my next project. Thanks for passing on what you've learned over the years!

    Bob
  7. Bomarc

    Bomarc Member

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    Hi Bob

    I'm an old plastic model guy myself. I guess I still am, since I do have a few models in the "stash", but I like the card stuff more and more. More of a challenge, and does my scratch-builder's heart good.

    Back at the secret modeling lair, I was able to cleaned up and aligned the struts. Here’s (hopefully) some better views:

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    I added one last bit of detail since I had these handy:

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    These are laser cut hex nuts made by Bruce Clemens via his “Avantcard” website (http://avantcard.biz/paper_models). He makes all sorts of neat little detailing tidbits. I got wind of his stuff from Rick (“papastumpy” here on Zealot I believe). The upper torque links had a large hex nut on either end of the mounting shaft, and these little “nuts” fit the bill. After that, it was finally paint time:

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    I painted all with Model Master Aluminum (enamel) except for the 4 little sleeves for the torque links (just below the main barrels in the pic immediately above) which where MM Steel. The standard “compare and contrast”:

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    Close enough. The paint looks smoother in person, but I kept some areas of the superglue coating rough. Kind of gives the parts a cast steel look. Nose strut next….

    Mike
  8. Bomarc

    Bomarc Member

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    So work continues with the nose strut.

    Even though the nose strut is about half the size of a main strut, it has enough unique features to drag out assembly. The first unique hurdle was the bent fork. Rolled a tube using an appropriate size punch for a mandrel, then cut a series of wedge shaped slots where I needed to bend it 90 degree:

    [​IMG]

    This slot business is actually what Orlik would have you do for the kit part, only that part is solid, rolled around a wire core, and you were to bend the wire inside after making the slots. This part is hollow on the real deal, and you can see the open end on one side, so I used a tube instead. After bending, coated with super-glue, sanded, coated, sanded, etc. until it was a smooth pipe:

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    In the upper part of the last pic can be seen the core part strut parts which were done exactly as the mains, only smaller scale. Next was to make the square knuckle that the fork mounts through. Rolled a tube that fits over the fork (snugly) and glued it in between a “U” shaped box:

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    Filled the voids around and in between with more super-glue taking care not to get any inside the tube and sanded to shape:

    [​IMG]

    This was the point where I was going to make the fork straight and drilled a hole through the assembly so that the wire in the core piece lock everything together:

    [​IMG]
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    To the right can be seen work started on the wheel axle, which utilized a cut off section of the fork part, plus added bits.

    At this point, checking the refs I had, I realized there was a discrepancy in what was built at the factory and what was in the field. After some inquires to knowledgeable folks at PM.com, I decided to mount the fork at what was "field conditions", which added a castor to the fork, and the fork wasn't in line with the main strut. I pinned the fork in the same manner as the full size prototype and thereby eliminated the need to actually glue the fork in place. Clipped off the wire from the strut core, and drilled a hole through the block and fork, angle set for “castor”:

    [​IMG]

    After that I made the torque scissors from rolled tubes and card:

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    And that’s where I left it:

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    The hinge “ears” on the strut are two layers of card super-glued in place, then sanded to shape and only then were holes drilled. The wire hinges will be ground down to a more reasonable length later. Some final views:

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    Note the open end of the fork tube on the “8-Ball” side.

    Last bit is the big honking shimmy damper and its associated linkages and that will be about it.

    Mike
  9. -Jim G

    -Jim G Member

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  10. Bomarc

    Bomarc Member

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    Man of few words, eh Jim? :)

    Put together the anti shimmy device (damper) that’s at the front of the strut. In yet another variation of the “dremel trick”, I punched out a bunch of small discs, this time stacking them on a wire with CA glue:

    [​IMG]
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    The damper has a shaft protruding from either end, so using the wire was a natural. Since it’s so small, I turned this down at my workbench, vice going into the garage like I had to do for those (dust factory) wheels:

    [​IMG]

    Kept the wires long to have something to hold on to for the next part. To make the mounting brackets, punched a hole and glued an over-sized part in place:

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    Trimmed and sanded to near final shape:

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    Once that was done, glued another piece and did it all over again:

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    Then sanded both together to the final shape so they matched and voila:

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    Wires trimmed and mounted on the strut:

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    Next was the little cylinder on the side that links to the damper:

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    Then the linkages:

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    They’re not ninety degrees to one another yet, so some adjusting of holes will need to be done. The whole assembly thus far:

    [​IMG]

    Mike
  11. jgderuvo

    jgderuvo Member

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    Wow. You've got skills!
  12. Bomarc

    Bomarc Member

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    Thank you jg.

    The finished article:

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    Mike
  13. Bomarc

    Bomarc Member

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    Did a quick parts inventory. It’s down to this:

    [​IMG]

    Some doors and hatches, rocket rails, and the next push, the “lumps” on the sides of the fuselage (gun blisters). The blisters started off with some good old basic card modeling. Nothing fancy:

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    While that was drying, needed to do some demo on the “drydock”:

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    I mentioned before this jig would be useful past the fuselage surgery of last year, now I needed to modify it so that I can install the side guns and wings. For the clear parts I’m using 0.010 PETG. No elaborate vacu-forming here, just some gentle bending to get it to the right curvature:

    [​IMG]

    Printed out some extra ribs for patterns to make a top and bottom shelf in the interior green color. These wedge the “glass” up against the body of the blister, eliminating the need to actually glue the plastic in:

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    Just trim the excess, good to go. Next was making the boots for the guns, done the same way as the tail gun boot was made several pages ago:

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    The “boots” painted and ready to be cut and fitted in:

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    Even though PBJ’s were operating without side guns installed, there was still a gun mount, so I added some roll tubes to simulate this. The boots installed, with some Elmer’s around the edges to set them in for good:

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    Interior side:

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    Some touch-up paint, and on the fuselage they go:

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    There’s a pretty nice gap along most of the sides. I’ll cut strips of the appropriate color and fill that in later. A few more doo-dads on the fuselage, then I can attach the gun nose (remember that?), fix up the control surfaces and attach those, then maybe, attach the wings…..

    Mike
  14. Bomarc

    Bomarc Member

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    Moving right along, last few nights were spent on the two “lumps” on the sides, now it’s the four bumps. I hate these, and always look for ways around making them. I saw this technique on the Russian “Card Army” forum, and thought I’d give it a go. Re-printed a scrap of the fuselage part for a pattern:

    [​IMG]

    Cut that out and the part itself, and did a little pre-shaping:

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    Crammed that into the cutout (which I had to line with card because I cut the hole too big), then lined the inside with Aleene’s tacky glue:

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    Out it comes, and on it goes:

    [​IMG]
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    I wasn’t too impressed with the outcome of the first bump. It was OK, but I decided to go with plan “B”. Using the same methods to get started, I then coated the whole thing with CA glue, then sanded to shape, coated, sanded, etc., until I got a matched set:

    [​IMG]
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    Did the same thing with the last bump:

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    Painted and mounted:

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    That’s pretty much it for the ancillary things on the fuselage.

    Mike
  15. -Jim G

    -Jim G Member

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    AMAZING! I love following this thread!
  16. Elliott

    Elliott Senior Member

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    I tell ya', go away on vacation for a bit, and when ya' come back the thing's almost done! Love the side windows and bumps. I was half expecting you to fill the bumps with glue or Sculpy. The landing gear, and your method of making it, is awesome!!!

    One question - At the bottom of post 93 (yesterday) you refer to gaps along the sides. I don't see them. Am I looking in the wrong place?

    Keep driving on Mike. This is a real thing of beauty!!
  17. Bomarc

    Bomarc Member

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    This is what I'm talking about Elliot:

    [​IMG]

    Lot's of light leakage there. A strip of gray card will cure that....

    Next task was focused on attaching the nose:

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    I had to make a fixture (left), the function of which will become apparent in a moment. The nose had to be glued in two steps. First step, glue the top portion:

    [​IMG]
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    WOW, look at that gap! I knew the rear bulkhead of the nose was warped, so that’s where the fixture comes in. Second step, glue in the bottom:

    [​IMG]

    The fixture lets me clamp the compound shape of the nose without crushing it. The clamp is a “Berna” clamp, a set of which I’ve had for ages (they hit the plastic model scene about 15 years ago). I find they’re really useful for clamping paper models as they don’t exert a lot of pressure, just enough to hold things together. Micro-Mark doesn't carry them anymore, but here's someone that does.

    While the nose was drying, work started on the slab armor pieces. The plates actually go over the joint line of the nose, making the Orlik parts too short. Also they’re full of rivets, and the plates seem to have a more monolithic appearance:

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    Cut them out to the new, longer dimension, with a beveled edge, then added a little air vent thing(?) that shows up in all the photos on the Pilot’s side:

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    Didn’t add it to the other one for reasons I’ll relate in a moment. So the clamp comes off, and the plate goes on:

    [​IMG]

    I beginning to think that “H” model Mitchells didn’t have the slab armor on the starboard side as there was no co-pilot. I can't find a pic of confirming one way or another, but it’s a moot point; Orlik forced my hand by including it and marking the location on the fuselage:

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    It’s why I didn’t add the vent to this side, but I’m happy to slap this plate on if only not to see B16 anymore. Say goodbye to our little red friend:

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    And that’s how you do that. Some eye candy views:

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    I think it has the snub nose profile pretty much. The hood doesn’t quite sit right now that the bulkhead’s been straightened out, so some adjustment will be required.

    Why yes, yes I did try the wings on:

    [​IMG]

    Looks like we got Mitchell in here…..

    Mike
  18. racc00n

    racc00n Member

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    Gorgeous build. Lots of lessons for me in following along. Thanks!
    jon
  19. Falsemuzzle

    Falsemuzzle New Member

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    oh my...i don't think i can say any praise for this build that has not already been said. just amazing!
  20. Bomarc

    Bomarc Member

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    Been woefully behind on updates, sorry. As this epic gets closer to the finish line, I start to get a little too focused. Now that I have a pair of struts to build to, I wanted to make a more positive connection in the wheel well. In Orlik's world, it's just a hole and a post to mount what's essentially a fairly heavy paper pendulum:

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    Not going to happen. So I made some sockets based loosely on the real article:

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    Printed out scans of the bulkheads that made up the walls of the wheel wells so I can set the angle to insure the struts are perpendicular (in that plane, they actual tilt forward a tad in the other plane):

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    Then I realized that the Orlik set-up was based on their somewhat thinner gear leg, and the sockets added a bit of dimension. It meant I needed to tear out the posts and cut them down a bit. But that was a good thing; it allowed me to add the angle of the forward cant of the legs, and I could solidly CA glue the part to the socket:

    [​IMG]

    So in a single assembly, I could capture the angles in both axis. I didn’t need a fancy jig to set it in place, just a couple of gauges to check my work using a dummy strut:

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    CA glues sets everything in place:

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    Now that there a solid base to mount the struts, I can cut down the struts themselves. In the little cheat sheet I whipped up, I determined an average distance between the top of the tire to bottom of the nacelle, and marked that:

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    Added the depth of the socket as measured from the dummy strut:

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    I did this method with a saw and drill to cut off the excess:

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    But it really wasn't necessary, for even with the CA glue coating, I could slice through the paper rolls with a knife, which I still needed to do after fit and cut, fit and cut, etc. I ended up with a lot less strut than I anticipated:

    [​IMG]

    But it’s just enough:

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    There’s enough “slop” in the socket to give me one last chance to make adjustments come time to permanently mount these, but the majority of the angles are set in now. I’m going to use slow epoxy, and that should be enough. Also the socket assembly gives me the opportunity to add shims inside as required to get a level stance in the overall model.

    Flaps and ailerons next.

    Mike