Scales for a flying glider fleet

[mbauer]

Originally Posted by ReynoldsSlumber

And the 1/200 Western Pacific Simpsons 737-300 is done! It glides rather nicely, slower than the Skyhawk at ~15 ft/s and with a shallower glideslope. The higher aspect ratio wings certainly help. It's still heavier than I'd like, though at this small of a scale, it's well nigh impossible to rectify the scale speed of ~2000 mph (!), so I'm satisfied with it.

As anticipated, the wing-body fairing put up a fight in trying to get all the edges to close up while also aligning to the graphics on the fuselage. It's gonna bug me a bit that it ended up 1/32" forward of where it should be on the body; so it goes! I did trim off the trailing edge that had overlap graphics for Homer's collar, 'cuz that just wasn't matching up. Good news is that, though the finished fairing is easy to deform, it springs right back, it's sufficiently stiff at this small of a size, and I didn't have to drastically modify the wing surfaces to carry through the fuselage for structure. Again the flexibility is actually nice for crash resistance—which I've already put to the test a couple times, with no damage.

This is the smallest wing chord that seems practical to make to fly well with decent scale model aesthetics. Going back to the original post on this thread, the 1/200 scale is a consequence of putting the 737 in the same category as the widebodies in this series. I'm a little concerned about how skinny the XB-70's fuselage will be at this scale but will give it a go at some point later. The alternative would've been to make the widebodies huge at 1/160 or else make an intermediate fourth scale category for the narrowbodies and bombers, which I'm trying to avoid. If it still ends up too small, perhaps I could make revisit some of the planes in this category at 1/180 instead of making the jump to the more standard 1/160. In any case, this model resolves my worry that accurate scale papercraft gliders can't be reliably made to fly well. It is indeed feasible!

Speaking of scale, on this prototype, it's funny how they had to draw Marge smaller than the other characters just to fit her hair, even though she's on the vertical tail.

Great to read it flies well! Like the construction photos, great detail on how you make them.

Weight is the real issue with paper, it is rather heavy when compared to other materials. Read somewhere for model making it is like scale sheet metal for the strength and weight.

Great to see how you're doing what you set out to accomplish! Looking forward to the next project.

Mike

[yankeekilo]

A long time ago, I put together a Vickers Viscount in 1.100. I left it at the school, and one of the instructors took it and threw it to fly, and amazingly, it did! I like your thread a lot, and I think that as long as aerodynamics weight, balance, and CG are correct, paper models will always fly.

[ReynoldsSlumber]

Good point on the sheet metal comparison, sounds about right on a strength-to-weight basis. Guess I need to go "thinner gauge." Or come up with "honeycomb panels," as in the foam sandwich that we were talking about before. Speaking of honeycomb panels, I've actually been looking for a source of honeycomb core cardboard (instead of corrugated), which is apparently common in Europe, though I haven't found anything thinner than like 1/4". Plus, to make something contoured, the honeycomb core would need to be separate and then assembled to the face sheets. Tricky!

Have you run across Flite Test's Master Series? To make those kits, they found a designer who adapted sheet metal forming techniques to foam core board. They don't sell plans of Master Series kits, unfortunately for my downscaling desires—they only sell foam board kits.

Thanks especially for the encouragement, Mike and everyone. Who says we had to outgrow show & tell? Too fun.

[ReynoldsSlumber]

Lucky that the Viscount has those loooong engines and big ol' schnoz, such that the balance was right without added nose weight!

[yankeekilo]

Originally Posted by ReynoldsSlumber

Lucky that the Viscount has those loooong engines and big ol' schnoz, such that the balance was right without added nose weight!

yes!! that was a lucky, unintentional flight

[ReynoldsSlumber]

Fleet scale plan revised again. Decided I could downsize the Rutan Voyager from 1/72 to 1/120 and attempt the resultant 5/16" (8mm) wing chord. Will likely go for a one-layer arc airfoil on that one, rather than fuss over a minuscule hollow airfoil section that wouldn't take kindly to a tip strike. Also may make the Beech Starship at 1/120, since the model I picked might not be quite fancy enough for 1/72 looks... though maybe it would be if I modify the sharp wing leading edge instep to be curved. Added the Edgley Optica, P.180 Avanti, and Rutan Boomerang (that's a lotta Rutan) to the wish list at 1/72, as well as the MiG-25 that Bruno just previewed for Scissors & Planes at 1/120. Moved the Dash 8 from 1/200 up to 1/120 based upon my recent experience with a Saab 340 static model at 1/160. (Apologies again about the "potato-vision" image—for some reason I still haven't figured out how to post images larger than 640 x 480.)


For the ones for which I haven't found the right downloadable plans, I'm putting out the call on the Design Requests forum! Any takers? VVA-14, SM-64, a fancier YF-23, the aforementioned Rutan Voyager (if the Murph's Models one can't be resurrected)...

[ReynoldsSlumber]

A not-quite-so-serious one this time, a bit of a departure from the series: a 1/72 "sport scale" F4U Corsair kit build, from Andrew Dewar's High-Performance Paper Airplanes set. The set, which is mostly sport gliders, can be found at some bookstores and toy shops in the USA as well as online of course.

When I first got the set, I wasn't sure how well I'd do at the Corsair, but that was before I had the experience of making the other planes in this thread. The Corsair builds kind of heavy, given the three-layer wing, though as it's meant for outdoor flying, it works well. I used Aleene's Tacky Glue, spread with a flat brush, and had no trouble with paper warping. Given the inevitable slight mismatch between the top and bottom printing and the stamped cuts, when I matched up the graphics on the bottom of the wing, the lower layer leading edge ended up forward a little. Meanwhile the elevator slot was a tad too wide, I wasn't a fan of the edge-to-edge paper butt joint under the tail, and I think the nose cowling got stuck in place before I had it on fully, as the nose ended up looking a bit long. Minor gripes aside, the shape is nice, certainly representative of a Corsair, and the fuselage is one continuous piece.


When it comes to flying, the elevator trim is touchy. I wonder whether the sharp lip on the cowling is destabilizing, or perhaps due to my glue usage the plane is a little tail-heavy. That said, I managed to trim it into a gentle left turn, perfect for launching with a right spiral that transitions to left—very satisfying. For hand launching, adding a belly tab would be nice; instead I made do with gripping the rubber band launcher hook.

I also tried out my indoor glider Concorde and F7F Tigercat outdoors. They didn't fare that well against fast throws nor against mere gentle breezes. They fly too slowly, and the paper is too thin to fully withstand launch and hard landing forces. Confirms that lightweight paper airplanes should stay indoors!

[mbauer]

Looks like some of those will be fun to fly.

Cover 65#or 90# Index cardstock for my Rockets/smaller aircraft.

Heavier than bond or text paper, but gives them a "toughness" for hard landings.

Mike

[ReynoldsSlumber]

Another revision to the fleet scale wish list here, and this time it's legible! (As it finally dawned on me that .jpg files [below 5 MB] get to keep their resolution, whereas .jpeg or .png get automatically shrunk.) The gray text lines are models that were "for practice." The columns of unused scales are omitted in this view; the intended scale wingspan for each model is in bold. Already-completed models are noted at right. I've got a ways to go—fun!

I moved the TSR-2 from 1/72 scale down to 1/120, to keep the length manageable and to make it the same scale as its recon plane buddies. It does mean that its wingspan will be one of the smallest on the chart at 3 3/4", yikes. Kept the Beech Starship at 1/72 after all.

Added the pterosaur Quetzalcoatlus northropi, in two scales. It'll be quite the trick to approximate such an organic shape. From what I've read, it'll take some forward wing sweep to balance out the long neck and big head. I'm not aware that any plans exist, never mind for a glider version. (Canon Creative Park does have a nice static pteranodon plan.)

Added the "what ifs" of three versions of the Aerion AS2 supersonic business jet plus the McDonnell Douglas/Boeing blended wing-body, 1990s 450 passenger version. Not that I've run across plans for those either.

Any pointers to good candidate model plans to fill the blanks, on the unlikely chance they exist, are highly appreciated! That would be the SM-64, VVA-14, and B-1B, in addition to the above.

Currently I'm making a few static models as gifts, and a couple of them overlap with this plan, so they'll be good practice for later making glider versions.

[ReynoldsSlumber]

See my separate 337 and OV-10 thread—I've posted the pictures and construction details there. Here I'll address some things it's bringing to mind relevant to the whole series of scale indoor gliders.

• Paper weight: Earlier I had been using artist's sketch paper of various thicknesses. It's easy to find them for cheap at art stores, in tear-off pads of reasonable sheet counts. Seems like they're slightly thicker than smooth paper of the same weight, and therefore they're stiffer, a serious advantage for flying models. Also they seem to hold up to glue better. But I realized that the textured surface was causing mottled inkjet print quality, so I'd have to switch to smooth text/cover paper.
  On the 337 I used 40# cover paper (~100 gsm). I thought it could be a happy medium between the 65# cover (176 gsm) (see Mike's recs on this thread) and 24# bond/60# text (89 gsm). It turns out that 40# cover is too thin, at least for fuselage sections. Even a moderate layer of glue and a bit of time is enough to soften it, and then it's like pushing a rope to get it to fit onto the next fuselage segment. Shark teeth tabs turn into wet noodles. Likewise the paper softens rapidly as you flex and work it into shape and position. Blech.
  So the hunt is still on for the right paper, whether that's 32# bond/80# text (118 gsm) (as Mike was looking at) or perhaps that for the rear fuselage and say 40# bond/100# text (148 gsm) for the front fuselage... if something like that is reasonably available.
  Sure would be nice to find a paper that's "fluffier," i.e. thicker but lighter! And still with a smooth surface? Tall order.
• Glue application methods: I've been trying out Aleene's Tacky Glue in a syringe with a tapered tip, with the idea that I could lay down just the right amount of glue and not have to spread it with a toothpick or finger before sticking the parts together. Could work; needs more practice. Could be nice to find a squeeze bottle with a small diameter tapered tip, so that it would be easier to control the pressure on the glue. Though maybe the tip would get air in it and dry out with glue still there, not sure.
  I did try out using a brush for covering a larger area, worked OK. I should try that for tabs etc. too. Seems like it would be very controllable but a bit messy, wasteful of glue, and more effort.
• Spine: The 337's fuselage ended up rock solid, too strong really, and therefore a little heavy with all of the glue I slopped over the spine's tabs. I think I need to make the spine with thicker paper and few glue tab attachment points, just at the nose, wing, finger grip, and maybe a couple more touch-off points on the fuselage skin. Trust in the monocoque structure!
• Foam rubber nose: The 337's front spinner, made out of 2mm thick children's craft foam, is holding up well so far, even to direct hits on furniture. Think I'll keep trying this method on the noses of upcoming builds.
• Finger grip: At 0.0035" (0.09mm) it's just a little too flexy. I need to find a slightly thicker clear plastic, not so thick that it'll crack when I fold over the attachment tabs.
• Outdoor gliders: Per several people's encouragement toward building stronger, I could see doing a series of outdoor planes, using 65# cover paper and building heavier for faster flight against breezes. It would be pretty darn cool! It would mean building bigger as well I think, a step or two up in scale for each of the categories I laid out earlier. Rather than wingspans in the 4-10" range as I'm doing for indoors, it would mean wingspans in the 5-12" range. And rather than a finger grip, it would definitely call for a rubber band launcher hook.