Holverson Swinger RG – resurrection of a nostalgic classic

Discussion in 'Rocket Boosted Gliders' started by Rktman, Jan 18, 2019.

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  1. Jan 18, 2019 #1

    Rktman

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    Eric Noguchi

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    Rick Needham's Swinger pic.jpg

    I’ve wanted to build the Holverson Swinger RG ever since I laid eyes on it. Although the Hot Turkey was one of the first (if not THE first) swing wing glider that used a single pivot hinge for both wings, the Swinger was the first (circa 1999) to my knowledge that combined both a single hinge and an innovative piston and control rod mechanism to keep both wings locked back in a folded position during launch.

    Yup I was hooked. While the Swinger is anything but a quick easy build, I couldn’t resist having something that is just so cool and absolutely out of the ordinary (pretty sexy looking as well IMHO). So the extra time and care I intend to take will be worth it.

    (The image above is a frame capture from Rick Needham's Swinger video).
     
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  2. Jan 18, 2019 #2

    K'Tesh

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    Looking to building one myself. Keep us posted.
     
  3. Jan 18, 2019 #3

    jmuck78

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    +1. I have a built version of the Holverson Swing Wing and it is (or was) gorgeous. I have had to replace the small body tube / nose portion several times because the piston movement seems to destroy it. I probably didn't build it correctly, so I have always wanted to build another.
     
  4. Jan 19, 2019 #4

    Crawf56

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    Are there kits and/or plans available?
     
  5. Jan 19, 2019 #5

    kuririn

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    Plans are at YORP under Holverson Designs. Picked up an almost ready to fly version from eBay about a week ago. Foam construction, the nose cone broke off while I was trying to trim it for flight. Might replace it with a balsa one. Will try for a launch this weekend. Cheers.
    IMG_20190118_200127.jpg IMG_20190118_200607.jpg
     
  6. Jan 19, 2019 #6

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    Eric Noguchi

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    Since there are a lot of fiddly bits and complex shapes that would be difficult for an X-acto to slice out accurately, my birthday present to myself was to have it laser cut. This one time I thought it was justified because components have to be meticulously aligned and pieces need to fit together precisely for things to work. (The wings weren’t lasered—more on that later).


    laser cut parts.jpg


    I figured this wouldn’t be a fast build because I also had to figure out where to get all the tiny hinge mechanism bits and pieces like the miniature bolt, washer and locknut and other assorted doodads like the balsa piston and control rod.

    I decided to build for strength and sturdiness instead of flight duration, so to do it right I had to get my hands on some good C-grain hard balsa for the fuselage and other components and medium density C-grain for things like the wings and rudders and reinforcement pieces. Since it’s rare to find anything like that at the hobby shops in my area I had to source it from SIG and SpecializedBalsa.

    I also opted for a thicker-walled “tough tube” for the engine pod since I know how much of a beating it’ll get from the ejection charge and sliding piston. One encouraging thing was that it took twice the effort and twice as long to slice off a piece for the motor pod.

    IMG_2250.JPG
     
  7. Jan 19, 2019 #7

    Rktman

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    Eric Noguchi

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    You can download the plans here: https://www.oldrocketplans.com/hdi/hdi2004/hdi2004.htm

    If you're thinking of getting it laser cut I can send you the Illustrator files I used, or I can export eps files which they also take.
     
  8. Jan 20, 2019 #8

    Rktman

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    Eric Noguchi

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    The well thought out plans/templates are comprehensive enough to include a dihedral jig for the V-tail. This really simplifies sanding in the dihedral angle and locking it in accurately while the tail’s two glued-together root edges dry.
    stab jig.JPG

    To contain costs I didn’t get the wings laser cut (it would’ve doubled the cost). I went old school and created a paper template to transfer the outline to the balsa, then used a hobby knife to slice things out.
    I cut outside the lines where there were going to be small, tight angles and radii. Glad I did because chips broke off along the grain lines, especially around the circular wing hinge area where I was afraid they would. I used emery boards to file the curves down to their final shape.
    paper template.JPG
    IMG_2243.JPG
    IMG_2247.JPG
    Unfortunately I didn’t have time to get more done. I had to put aside the airfoiling of the flight surfaces till tomorrow. It’ll take some time anyway since I’ll be shaping it in with sandpaper instead of using my razor plane to speed things up. Since the V-tail is only 3/32” balsa and the wings 1/8”, I know from sad experience how easy it is to mess things up with just a single stroke of the plane with relatively thin balsa. I decided to take my time and be careful with this build. I’m in no hurry, my club has hardly had a chance to launch due to the sucky weather the past 12 months and it looks like more of the same for the next few weeks. Oh well, more time to do leisurely builds this Winter.
     
    Last edited: Jan 20, 2019
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  9. Jan 22, 2019 #9

    Doug Holverson

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    Here are the laser cutter patterns for the Swinger and others. They're in R 2013 dxf format.
     

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  10. Jan 25, 2019 #10

    Rktman

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    Eric Noguchi

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    Finished up sanding in the dihedral and gluing the V-Tail together. The included jig made it a breeze and ensured an accurate fit.
    V-tail.JPG

    Spent the rest of the morning sanding in the symmetrical airfoils per the instructions. Although I suppose I could have as easily carved in the more widely used Clark Y shape, I felt there might be a reason to stick to the instructions, for example IIRC a lot of the construction directions for the Edmonds line of gliders cautioned NOT to airfoil the flight surfaces because it caused problems if you did. I decided to err on the side of caution and go with the Swinger instructions.
    wing airfoil.JPG

    To strengthen the wings and add color I decided to tissue them as well as the V-tail and rudder. Doping them is the worst part because of the horrendous fumes. Had to work in the garage so even 2 coats is going to take a good part of the day because the freezing temps makes things slow to dry.
    doping.JPG
     
    Last edited: Jan 25, 2019
  11. Jan 26, 2019 #11

    Rktman

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    Eric Noguchi

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    The next part of the build was the most worrisome: making sure all the parts of the fuselage were perfectly aligned in relation to each other once glued. The forward end has a core and two doublers that go on either side, and the tail boom has to be exactly 1/8” away from the doublers (this will form the space that the swing wing “axle” will pass through. It’s a clever way to avoid having to drill a hole through the fuselage while ensuring it’s at perfectly the correct angle. Even a little bit of deviation on the X or Y axis from manually drilling could throw off the alignment of the wings and mess up where it passes through the wing support disc. (The screen grab below might make things a little clearer how it all goes together).
    fuse layout.jpg

    I marked the left side doubler 1/8” away from the core piece (this is where the forward end of the tail boom will go).
    fuse assy-1.JPG

    Using a piece of 1/8” scrap, the tail boom is butted up against it and glued in place with CA.
    fuse assy-2.JPG

    The scrap is immediately removed, leaving a perfectly aligned 1/8” channel for the “axle” bolt to pass through. The right side doubler is then glued over the core to complete the "axle" channel.
    fuse assy-3.JPG

    Here you can see the tail boom in place, and the incidence angle (decalage) it forms for the V-tail “stab”. That’s one of the reasons why it was critical to get things absolutely aligned.
    tail incidence.JPG
     
  12. Jan 31, 2019 #12

    Rktman

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    Eric Noguchi

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    Glued in the support disc that the wings pivot on.

    The reason for the channel created earlier might be clearer now that it’s in place. The “axle” bolt will pass through from the bottom and up through the hole in the disc’s center, then through both wings.


    IMG_2280.JPG
     
  13. Jan 31, 2019 #13

    Rktman

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    Eric Noguchi

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    Spent some time carefully sanding the fuse to round off edges for streamlining. The “pylon” area forms the tunnel for the control rod and also serves to exhaust the ejection charge from the bottom vent hole.
    IMG_2327.JPG
     
  14. Jan 31, 2019 #14

    Rktman

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    Eric Noguchi

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    Finally finished tissuing all the flight surfaces as well. They’ll get a final coat of thinned dope, along with the fuselage to strengthen and moisture proof it.
    tissuing done.JPG
     
  15. Jan 31, 2019 #15

    Rktman

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    Eric Noguchi

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    Took me over an hour to freehand cut out the top and bottom exhaust ports from the denser, harder “tough tube” I decided to use for the motor pod. I inserted a spent engine to support the tube from the inside since I had to use extra pressure to cut through the thicker material. Had to go slowly to avoid having the blade slip and slice through someplace it shouldn’t. Miraculously I didn’t accidentally remove any finger parts or body tube outside of where I needed to cut. Came out with fairly clean edges too.

    This is the top port.
    top exhaust port.JPG


    And the bottom exhaust port and slot for the control rod.
    bottom exhaust port.JPG
     
  16. Feb 1, 2019 #16

    Crawf56

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    Great work. :cool:
     
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  17. Feb 2, 2019 #17

    Rktman

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    Eric Noguchi

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    Next order of business is manually drilling a hole for the hinge “axle” through the pivot point of the wing. A 1/8” launch lug will be pushed through the hole as a sleeve to protect the balsa from the bolt threads.

    While not noted in the instructions, the OD of the launch lug is actually 3/16” and this is the bit size that needs to be used. I slowly nibbled my way through both taped-together wings, being careful not to use too much pressure and split the balsa.
    IMG_2364.JPG

    Next came the hole for the 1/8” dowel that the elastic will be looped around. (This was a bit faster and easier since I could use a pin vise to speed things up).
    IMG_2376.JPG

    A small 1/8”L x 1/4” square of spruce is used as reinforcement in this notched area. This is where the control rod will sit, locking the wings back into their folded launch position. I had to substitute basswood since spruce is rarer than hen’s teeth around here (didn’t feel like paying $38 shipping for one skinny little 1/8” square spruce stick online). I soaked it in Minwax Wood Hardener overnight so it’s now really hard and should stand up well to the wear and tear.
    IMG_2380.JPG

    With the wings overlapped, the control rod will sit between the two notched areas to keep both wings locked back in launch position.
    IMG_2404.JPG

    The next step is to install the launch lug “sleeves” in the pivot hole. It fits nice and snug in its new 3/16” dia. home.
    IMG_2409.JPG

    Locked it in place with a drop of CA, and a single edge razor blade was used to carefully trim off anything that protruded above the surface of the wing.
    IMG_2416.JPG
     
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  18. Feb 2, 2019 #18

    Rktman

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    Eric Noguchi

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    The last item is to glue in the 1/8” dia. X 3/8”L dowel that the rubber band will be looped around.
    NOTE: decide which wing will be the one on top. The instructions don’t mention it but the top wing will have the dowel installed on its top surface while the lower wing will need to have the dowel installed on its bottom surface, or you won’t be able to fold the wings closed.
    IMG_2425.JPG

    The blue area is where I didn’t put in any airfoiling at all because I reasoned it’s the hinge area and should be flat so both wing surfaces could slide as easily as possible across each other. It also allows them to sit as flush as possible against each other when folded to minimize drag and turbulence and any possible flutter.

    I also wanted to leave as much thickness as possible on the leading edge root where the red arrow is pointing because this is the spot that will slam up against the fuselage once the wings are allowed to swing forward. Considering also soaking that edge with CA to further strengthen it.
    IMG_2427.JPG
     
  19. Feb 3, 2019 #19

    Rktman

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    Eric Noguchi

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    Since the wings are done for now it’s time for the V-tail to get attached. Did my best to square up the fuse and get it as level as possible. The table (or floor?) is a little off, so I just made sure the bubble level was off the same amount. Here’s where the dihedral jig proves its usefulness once again.
    IMG_2350.JPG
     
  20. Feb 3, 2019 #20

    Rktman

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    Eric Noguchi

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    Bending the control rod was not quite as easy as I thought it would be. Getting it to be exactly the shape shown in the instructions with the bends on the same plane turned out to be problematic.
    wire bending diag.jpg


    I resorted to fabricating a simple jig after the first couple of tries left bends that were too far apart or not far enough apart or not parallel when viewed straight on.
    wire jig.JPG

    Next up is assembling the heart of the piston wing-anchoring and deployment mechanism.
    I’m guessing this might not be as easy as I think, as the balsa piston will be between the engine block (blue ring) and piston stop (green ring and ply disk) and shoving them in from the bottom and the top respectively will create a glue “dam” ahead of where they’re situated (and be in the path of the piston, which may interfere with its full range of movement). Removing the glue is going to be…well, a challenge since the piston will be in the way and I’ll pretty much be working by braille through the small vent openings.
    Piston mechanism layout.JPG

    There’s an engine hook (not shown in the previous pic) that also gets installed after the engine block. To simplify things and deal with the buildup of glue on the piston side where it would be hard to clean up, I decided to reverse the order of things. I dry fit the engine hook then temporarily removed it so that the bent tab thingy wasn’t hanging down inside the tube interfering with things, smeared glue 2.75” up inside from the aft end, replaced the engine hook, then shoved the engine block down from the forward end (instead of up from the aft end) until it bottomed out against the hook tab. Most of the excess glue glopped up on the opposite side from the piston, where I could easily reach it and clean it up from the aft end.
    A mylar anchor ring neatly finished up the hook installation.
    IMG_2428.JPG

    Installing the bulkhead (piston stop) comes next, and here’s where the instructions get confusing. They specify that the bulkhead should be 0.75” from the forward end of the tube, but that’s way beyond where the control rod would hit the forward edge of both the top and bottom vent holes (I’ll try to remember to snap a pic once the engine pod is assembled. It’ll make much more sense then).
    Anyway I put the balsa piston into the tube and slid it forward until the hole for the control rod hit the forward edge of the vent hole, and determined that the bulkhead should actually be 1 1/8” from the front of the engine tube instead.

    Cleaning out the piled up glue with a damp Q-tip had to be done quickly before it set. Luckily I have an LED headlamp that’s attached to a headband and with the bright light I could pretty much see where to guide the swab. Patient seems to have survived; this part of the operation went much smoother and easier than I thought it would.
    IMG_2431.JPG

    The assembled motor pod with piston installed. At ejection, the piston is forced forward and pulls the control rod out from between the wing notches, releasing them from their folded position to swing out to glide position.
    IMG_2436.JPG
     
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  21. Feb 3, 2019 #21

    Rktman

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    Eric Noguchi

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    While the glue was curing I sanded a flat spot on the bottom of the V-tail to give the rudder more surface area for the glue to grab on to.
    IMG_2441.JPG


    Rudder’s done except for fillets.
    Lots of little things to still take care of but things will start to come together faster now that the major things have been taken care of.
    View attachment 2447
     

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    Last edited: Feb 3, 2019
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  22. Feb 4, 2019 #22

    Massrokit

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    Nice clean assembly
     
  23. Feb 4, 2019 #23

    Rktman

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    Eric Noguchi

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    Thanks, appreciate that!
     
  24. Feb 4, 2019 #24

    Rktman

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    Eric Noguchi

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    Motor pod attached and being filleted. Getting closer to wrapping things up.
    IMG_2450.JPG


    Fuselage reinforcement stringers glued in place and trueness adjusted by eyeball calibration.
    IMG_2462.JPG

    Pretty much all that remains is installing the pivot hinge and wings, and final wing position adjustments for boost and deployed modes. Knock wood but this build has been going far smoother and more trouble-free than usual.
     
  25. Feb 4, 2019 #25

    Massrokit

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    Are you going to use the wire nut? I believe the ease of moving the piston, safety and the additional weight of it in pod area.
     
  26. Feb 5, 2019 #26

    Crawf56

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    Make it happen, cap'n. ;)
     
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  27. Feb 5, 2019 #27

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    Eric Noguchi

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    Couldn't find a similar size or color so I got a smaller grey version (actually 25 since no one sells singles). Might paint it orange to match the original.
     
  28. Feb 5, 2019 #28

    Rktman

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    Eric Noguchi

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    Roger that! Anxious to get to a park for some trimming and to see how it glides.
     
  29. Feb 5, 2019 #29

    Rktman

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    Eric Noguchi

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    Temporarily installing the pivot hinge “axle” bolt so I can test fit the wings.
    IMG_2467.JPG
     
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  30. Feb 5, 2019 #30

    Rktman

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    Eric Noguchi

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    …Aaaand I think I jinxed myself with that comment about things being so trouble-free. Judging by the trial fit I just did, the control rod won’t fit between those basswood inserts from post #17.

    Not sure what happened, my template matches the plans exactly and I even took the precaution of drilling out the marked hinge and dowel holes on the template and hardening them with CA so I could use them to guide my drill bit when I started to make the holes. There was a tiny bit of drift, not more than a millimeter at most but those basswood reinforcers are a whole 6.4mm wide and I’ll have to remove virtually all of it.

    My takeaway from this is a tip to anyone doing a Swinger build: don’t install those hardwood reinforcers until you get to this step where you have to fine tune the launch and glide positions of the wings. Had I done that, I could have used some thin CA-hardened 1/64” or 1/32” ply instead.

    Because it looks like I’ll have to take most—if not all—of it out, the build may be delayed for

    the better part of a day or more as I try to remove those hardwood pieces with a file. Faster with a dremel…much longer if I screw things up with the dremel. We’ll see.
    IMG_2471.JPG
     

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