The 'daydreamers' thread...post your craziest designs and concepts here

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Twodeaddogs

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there was one proposal to fly a steel cable up to space, held up there by a low earth orbit station and then have supplies sent up along the cable by a kind of high speed cable car. the snag was that the cable would be blown allover the place by the earth's weather so it didnt work.
 

Tiger Tim

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there was one proposal to fly a steel cable up to space, held up there by a low earth orbit station and then have supplies sent up along the cable by a kind of high speed cable car.
Been a while since I thought too hard about space stuff but orbital velocities being what they are wouldn’t the top end of the space elevator need to be just a little above geostationary orbit? The “above” I think would be necessary to account for the weight of the cable.

Or do I have that backwards?
 

rbarnes

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Still dreaming on this... if you did a single boom under the rear prop you should be able maintain the original Zenith control layout and be able to set it up as a trike or a tail dragger ... hmmm

TWINSTOL750_2td.jpg
 

PMD

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Thread subject is both designs AND concepts, so can I throw another idea/question into the ring?

I am one of those "maximize the radius of gyration" crazies. I built commercial airboats that used gunwhales made from 0.040" 5052 formed to make a straight vertical inner wall, a 7" walkway on top and vertical freeboard with appropriate (calculated) angle at the waterline. I made a giant jig and poured these full of PU foam to make them into structural beams with permanent flotation (the foam being one big and very light shear web). We did some testing and could put TONS of load in bending into the shallow dimension (easy as there was one on each side to press against). Encourage by that, I made some experimental prop blades with Al skin and foam core and you could support each end and stand a 220 lb. me mid span - again against the thinnest dimension.

Ever since, I have had dreams of building an airplane wing that was a true monocoque. Imagine if you could about a 14' wing with taper (40" root, 30" tip for 72 sq. ft. for two wings) and washout that attached DC-3 like to a flange at the inboard end. As much laminar flow as possible (worked fine in AA-1 with NO washout). Burried inside of the wing would be an aluminum pocket into which a fuel tank bladder was installed from the inboard end. Glue a few ribs in place, but mostly count on an 0.050 or 0.063 2024 skin to be THE structural member - kind of Ted Smith/Aerostar like but without all of those damned countersunk rivets to set. Minix wingtips, of course, screwed into place but with extreme fairing of screw holes (removeable filler??). As with Bede/American/Grumman torque tubes for aileron and flap actuation, but some geometry to let the flaps have a blown gap when deployed.

Once again, the lessons I learned (the hard way) would be applied. Prepping the surface to get good bond between aluminum and urethan EXTREMELY important. Also, using PU that is quite flexible/soft. With all of the surface area involved, you don't need much actual strength to have an effective shear web, but if the foam is rigid, it will eventually fracture from impact and maybe even the simple act of dimension change from thermal range.
 
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jedi

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Can you keep the foam from inflating the wing like a big balloon?

Might need a mold to keep the wing profile against the expanding foam. Comments?

I am picturing the science experiments where the foam rises out of the cup with a considerable overflow.

Powerfin props have a core under carbon fiber but they are made in a mold and have a different material/process for the core.
 

PMD

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Can you keep the foam from inflating the wing like a big balloon?

Might need a mold to keep the wing profile against the expanding foam. Comments?

I am picturing the science experiments where the foam rises out of the cup with a considerable overflow.

Powerfin props have a core under carbon fiber but they are made in a mold and have a different material/process for the core.
Yes, you do indeed need a mold (actually 2, since even with symmetrical airfoil cross section I would want washout to be incorporated from manufacture) but spraying foam progressively and getting a rapid rise and great bond is done regularly in the building products industry (see "MIP"= Metal Insulating Panels as used for structural building envelopes and refrigeration plants). When I made boats it was a matter if mix liquid and pour - that needed a lot more time to rise and was done in one big pour per beam but still worked quite well.

Thanks for the Powerfin reference. Like what they have to say.
 
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