Aircraft fabric covering: Great for boat tails etc:

[Logic]

Coroplast over a steel tube frame seems to be the 'go to' method of building Boat Tails etc here.

There's a lighter, easier method:
Light Aircraft and gliders/sailplanes use a similar underlying frame, but this is then covered with an aircraft fabric that is pulled so tight that it does not crease or flap in the wind.
It's Pulled that tight first by ironing the fabric which shrinks it, then by 'doping' the fabric which pulls it even tighter and makes it airtight.
Its then spray painted much as one would normally paint a car.

This would make for a lighter, neater, more professional looking, boat tail etc.
No steps and bolt heads etc means more aero too.

ie: You build your frame out of tubing of some sort:
steel, aluminum, glass/carbon fiber, balsa wood, recycled fishing rods, bamboo or whatever.
Then stretch aircraft fabric over it using this tried and tested method.

Here are a couple of links on the process to get you started:

https://www.youtube.com/playlist?lis...8E69E46A3F6FC2

https://www.google.com/search?client...&bih=906&dpr=1

With my background in building gliders etc I don't know why I didn't think to mention it sooner!

[Piotrsko]

Don't forget every three inches or so large pieces are "rib stitched" to a backing structure so they dont oil can in the open areas between structures. However that is dependent on air speed which here isn't fast enough for maximum stitching. Also you can collapse the structure after shrinking if it isn't strong enough.

[Logic]

Some pics of fabric coverings


https://twoscenarios.typepad.com/.a/...0abb970b-450wi

https://www.euroga.org/system/1/user...t_22.13.29.png

https://www.youtube.com/watch?v=tDILJ7ZlzAw

[freebeard]

With my background in building gliders etc I don't know why I didn't think to mention it sooner!

Does the doping and paint rigidify the surface or does it remain in tension?

[Piotrsko]

Originally Posted by freebeard

Does the doping and paint rigidify the surface or does it remain in tension?

Both. Dopes continue to shrink some after drying until it looses plasticity in the sun and cracks, the modern synthetic finishes don't shrink as much but last longer. You can apply decorative coatings, films or decals that aren't structural. Any paint thickens the surfaces and makes it slightly more rigid than bare. Rigid is a benefit, not a requirement. Common to see warped surfaces after a while of sun exposure. Still cant walk on a fabric surface without ruining it.

You don't want floppy fabric, suspect drumming from looseness is kinda fatal.

[freebeard]

Sounds like a boat tail would need to be a closed manifold rather than having an open [front] end, else a substantial bulkhead.

[Logic]

Originally Posted by freebeard

Does the doping and paint rigidify the surface or does it remain in tension?

erm... It does to a certain extent freebeard, but yes; it remains in tension.
I do recall paint cracks (not the fabric) if someone pressed on a 'panel' hard enough, but nowadays that can be avoided completely by adding a plasticizer/plasticiser to std (2K) car paint.

[aerohead]

Originally Posted by freebeard

Does the doping and paint rigidify the surface or does it remain in tension?

The doping provides additional 'shrinking' to Dacron cloth, plus the 'rigidification' as it were.
Aluminum base - coat ( UV protection ) and color top
-coats alter the 'look', plus also add some additional fraction of stiffness.
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Anyone who can access the annual Fly-In at Oshkosh, Wisconsin, for a modest fee, join the Experimental Aircraft Association ( EAA ) on-site, which avails you to cheap on-site camping, and free fabric-covered aircraft workshops conducted by Alexander Sport Air, plus composites, welding, etc.. You'll also get a 'free', one-year subscription to the EAA magazine.
You'll also have access to free WICK's and Aircraft Spruce & Supply catalogs, which provide DIY materials perfect for aero-modding.

[aerohead]

Originally Posted by freebeard

Sounds like a boat tail would need to be a closed manifold rather than having an open [front] end, else a substantial bulkhead.

Yes, the tail needs to integrate to the host body in an airtight seal, otherwise pressure recovery is adulterated by the 'bleeding.'

[Logic]

Here's a nice write-up on on different fabric types etc:
https://www.kitplanes.com/which-fabr...-going-to-use/

Most interesting is Oratex:
"...Oratex is based on a woven polyester fabric, but unlike other aircraft fabric systems the weave filler, UV protection, and color coats are added at the factory..."
https://www.kitplanes.com/oratex-aircraft-fabric/

ie: Just pick your color, stick it on and heat-shrink it tight and done!
(I have no experience with this new stuff)