Scales for a flying glider fleet

[ReynoldsSlumber]

My main interest these days is in scale model airplanes that are flyable as indoor gliders and that are representative enough to be display models. In thinking ahead to the models that I might like to build over the next several years, I'm trying to balance these factors:

• Have a common scale, so that models can be compared to each other.
• Have the models be big enough to be built accurately enough to look close to the real thing while in the air.
• Build the models big enough to be made light enough per their wing areas such that they glide slower.
• Keep the models small enough for good structural integrity and crash resistance.
• Make the models small enough that the fleet doesn't overwhelm my living space.

To decide what scales to use, I listed the prototypes that I'd most like to model and made a table of their wingspans at various scales. See the attached image. The fewest number of scale classes I could figure on was three:

• 1/72 for fighters/general aviation aircraft: This was a tough one, and I'm still wavering over downsizing to 1/87 given how big the A-10 and Rutan Voyager are looking, but if I did then the littler planes would get pretty darn small.
• 1/120 for medium bombers/reconnaissance planes: The SR-71 drove this category.
• 1/200 for heavy bombers/transport aircraft: The XB-70, my favorite of the bunch, drove this category. Dunno whether I'd actually go through with that monster An-225, haha.

I'm interested in your thoughts on these scale choices, based upon your experiences!

I appreciate how fun Ojimak models are and the work that went into making them easier to build and flyable, but I'm really looking for contoured rather than faceted surfaces. Has anyone had luck with converting static models to be flyable as paper gliders? I'm thinking that what it takes will include:

• Make the wings be just the layers of paper glued together (no volume inside), with some camber, for a better low-Reynolds number airfoil.
• Carry the wing structure through the fuselage.
• Beef up the nose internally, for nose weight and for crash resistance.
• Any propellers would be removable, for display only, not for flight.
• Cruise configuration, so no landing gear.
• Omit certain minor details, for less weight and drag.

The nose weight will be especially tricky to get right, since it takes knowing in advance how much paper and glue need to go up front to properly locate the CG. There may be no avoiding having to build a second model every time... or maybe it's possible to trim it with the nose stuck on temporarily before gluing it on permanently.

Has anyone else done this kind of thing before? The closest I've run across so far are a few of the Ojimak models that are contoured, like their 1/230 scale Concorde, and some old books like Michael Johnson's Paper Planes No. 1 and No. 2. Also, consider this an open invitation to join the journey and make your own scale model gliders!

If you can recommend any models with roughly the described size and degree of accuracy that could be candidates for glider conversion, I'm all ears! So far I'm looking at Scissors & Planes models, of course, as well as some others. A few of the prototype planes I'm interested in are pretty obscure.

By the way, I'm debating adding a nose hook to each plane for potential park flying with a light rubber band launcher, like Ojimak does, but between the hit on accuracy and the likelihood of water damage from grass, doubt I'll do it.

I'm also considering making the models easier to hold for launch, whether that's with a tab on the belly like with some Ojimak models, an extra ventral fin like with "4D Paper Airplane," or something out of clear plastic sheet. Again, for accuracy's sake, I'd rather not; it's just that some designs and sizes are awkward to hold for launching and/or could be crushed with even a gentle grip. That was my experience with a couple (very nice!) PaperAircrafts.com faceted flying models.

[mbauer]

welcome to the site!

Really like your user name!

I've had luck with flying cardstock models.

Using cardstock the model will be heavy. Found that the larger sizes fly better. I use symmetrical airfoils to give the wing strength and also an actual airfoil. Using symmetrical the ribs are are the same top and bottom, makes it easy to form the wings.

Tested: catapult rubber band launch models, hand free throw gliders, rubber band power wind up models, stomp rockets and jet-powered versions.

Completed a prototype pulsejet powered model, that one day will be converted into a flying R/C model.

One of my designs is in the download section section, it is designed to fly. Not exactly scale but close enough to see what it is modeled after:


https://www.papermodelers.com/forum/...&downloadid=71

Instructions are near the bottom of this page:
https://www.papermodelers.com/forum/...yid=21&page=18

The Jet-Power versions used an internal air bladder to supply the "Jet" power. Surgical tubing sealed at one end and a small plastic bead in the other end for a thrust nozzle/fill port. Used cans of keyboard computer cleaning air to fill the surgical tubing up like a balloon.

The second link in my signature is a thread on the flying models I did many years ago. The third link is to my project page with different stuff I experimented with.

Mike

[mbauer]

Originally Posted by ReynoldsSlumber

My main interest these days is in scale model airplanes that are flyable as indoor gliders and that are representative enough to be display models. In thinking ahead to the models that I might like to build over the next several years, I'm trying to balance these factors:

• Have a common scale, so that models can be compared to each other.
• Have the models be big enough to be built accurately enough to look close to the real thing while in the air.
• Build the models big enough to be made light enough per their wing areas such that they glide slower.
• Keep the models small enough for good structural integrity and crash resistance.
• Make the models small enough that the fleet doesn't overwhelm my living space.

To decide what scales to use, I listed the prototypes that I'd most like to model and made a table of their wingspans at various scales. See the attached image. The fewest number of scale classes I could figure on was three:

• 1/72 for fighters/general aviation aircraft: This was a tough one, and I'm still wavering over downsizing to 1/87 given how big the A-10 and Rutan Voyager are looking, but if I did then the littler planes would get pretty darn small.
• 1/120 for medium bombers/reconnaissance planes: The SR-71 drove this category.
• 1/200 for heavy bombers/transport aircraft: The XB-70, my favorite of the bunch, drove this category. Dunno whether I'd actually go through with that monster An-225, haha.

I'm interested in your thoughts on these scale choices, based upon your experiences!

I appreciate how fun Ojimak models are and the work that went into making them easier to build and flyable, but I'm really looking for contoured rather than faceted surfaces. Has anyone had luck with converting static models to be flyable as paper gliders? I'm thinking that what it takes will include:

• Make the wings be just the layers of paper glued together (no volume inside), with some camber, for a better low-Reynolds number airfoil.
• Carry the wing structure through the fuselage.
• Beef up the nose internally, for nose weight and for crash resistance.
• Any propellers would be removable, for display only, not for flight.
• Cruise configuration, so no landing gear.
• Omit certain minor details, for less weight and drag.

The nose weight will be especially tricky to get right, since it takes knowing in advance how much paper and glue need to go up front to properly locate the CG. There may be no avoiding having to build a second model every time... or maybe it's possible to trim it with the nose stuck on temporarily before gluing it on permanently.

Has anyone else done this kind of thing before? The closest I've run across so far are a few of the Ojimak models that are contoured, like their 1/230 scale Concorde, and some old books like Michael Johnson's Paper Planes No. 1 and No. 2. Also, consider this an open invitation to join the journey and make your own scale model gliders!

If you can recommend any models with roughly the described size and degree of accuracy that could be candidates for glider conversion, I'm all ears! So far I'm looking at Scissors & Planes models, of course, as well as some others. A few of the prototype planes I'm interested in are pretty obscure.

By the way, I'm debating adding a nose hook to each plane for potential park flying with a light rubber band launcher, like Ojimak does, but between the hit on accuracy and the likelihood of water damage from grass, doubt I'll do it.

I'm also considering making the models easier to hold for launch, whether that's with a tab on the belly like with some Ojimak models, an extra ventral fin like with "4D Paper Airplane," or something out of clear plastic sheet. Again, for accuracy's sake, I'd rather not; it's just that some designs and sizes are awkward to hold for launching and/or could be crushed with even a gentle grip. That was my experience with a couple (very nice!) PaperAircrafts.com faceted flying models.

Using paper, weight is a big challenge. Lots of compromises will need done to finalize your designs. Less glue joints= less weight model. Glue joints add lots of weight, design with fewest you can.

Angle of Incidence is needed for these heavy models to fly: about 1.5 degree works for most

Lots of different ways to lose weight.

Wishing you luck with your designs.

Mike

[mbauer]

Originally Posted by ReynoldsSlumber

My main interest these days is in scale model airplanes that are flyable as indoor gliders and that are representative enough to be display models.
I'm interested in your thoughts on these scale choices, based upon your experiences!

The nose weight will be especially tricky to get right, since it takes knowing in advance how much paper and glue need to go up front to properly locate the CG. There may be no avoiding having to build a second model every time... or maybe it's possible to trim it with the nose stuck on temporarily before gluing it on permanently.

Has anyone else done this kind of thing before? ![/B]

Attaching a PDF file to help find the CG of the model. My designs always have a CG mark on the fuselage to show where to balance.2023 Plot CG Taper Wing.pdf

This CG design works for the initial locate, sometimes testing finds a better location. 9out of 10 times the CG location is usually perfect.

Hope this helps, questions?
Mike

[mbauer]

Should have added that modeling clay is a good way to add weight to the nose as needed. Watch for the oily kind that can soak in and destroy a model looks.

Lots of things have been used to properly balance a model for flight. One model of the X-1 used a dime up front to balance, it flew perfect. From a book of flying cardstock models. The pages were the models.

Book Name: Great American Airplanes to color, cut out & fly

Mike

[ReynoldsSlumber]

Mike, thanks kindly for sharing your advice, extensive experiences, and design materials! Nice CG locator there. Also impressed that you found a good non-combustion-based propulsion method. Those models look great in the air!

Looking at your other exploits, I'm also interested in rockets—made quite a few Estes kits and scratchbuilds once up on a time. Lately made a wee little 1/96 scale papercraft LTV Scout; might do a bigger one, as well as a Delta IV Heavy and a Titan IIIE.

[mbauer]

You're going to like the Rocket download section!

At the sizes you build, it will be very interesting to see the answer you have for flight! Looking forward!
STOMP Rockets are awesome if you want some flying power.

Weather here has been bad. Can count the sunny days since 1st of May on one hand. Started taking 10-day screenshots of weather to show how bad it is.

Have several Estes Power Rockets to fly if ground has a chance to dry and wind isn't blowing over 10kts.

New way of launching is at a weld shop for final welding and the hydrotest to 225lbs; allowing a 160PSI working launch pressure. 150lbs will be max due to regulator design.

It cost over $1000 to get some rocket engines to Alaska. Not many engines arrived for that money...

For a fraction was able to buy the parts and pay for everything: new way of launching rockets on the cheap. (Main parts are expensive: no shipping, you can buy locally)

Mike

[Draco]

About the sizes, I'll say just choose a maximun and minimun width, and go scaling between them. For example, your minimun width was... 8 cm. And the maximun width was... 30. Then 1/72 goes perfect from the Bachem Ba 349 Natter
to the VFW Fokker 614. Then 1/200 goes from B-26 Marauder to the Boeing 747-100. And then 1/250 from Boeing 787-8 to any other one in existence.
Of course you can choose any other limit and any other scales, but that's the idea

[ReynoldsSlumber]

Thanks Draco. Yeah, I'm also trying to factor in aspects other than strictly wingspan, like the length of supersonic planes as well as the bulk of some more complicated planes. For example, the Learjet could be a wide variety of sizes and still make a good glider, whereas something like the XB-70 only really works in a narrow size range, outside of which it gets too small to get enough shaping in there to make it look good or too big to be practical. Hence why the table of scales vs. wingspans is kind of choppy.

[papermate]

Thanks for sharing this very interesting subject, Mike.
A dumb question- how to read your cg locator diagram? Is there just one wing there?