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Step 4Main Wing
This MAIN WING is 87.25" long, 5.5" wide, 0.717" thick, which is approx 13% of chord.
The bolt holes to attach it to the UPRIGHTS are 48" apart.
The foil section is a very crude approximation of the NACA 63013 section. I left the trailing edge square, truncating the section, just to make the trailing edge stronger. The bottom of this foil is mostly flat, also due to laziness. There are lots of foil sections that would work. Try them all.
Scroll down to see the data for Trampofoil and Aquaskipper wings.
I made this wing from a fir board. It was a shelf I had on hand.
It was about the right size, straight grained and knotless.
I drew foil shapes on the ends of the board and shaped it with full-length passes with an electric planer. I made some mistakes so the shape wasn't quite what I had in mind, but because of the full-length passes the section is pretty uniform from end to end. Having made tapered foils such as rudders and centerboards before I was amazed how fast it is to make an un-tapered foil. Joy.
After the planer I smoothed it with a disk sander then hand sanded it.
Then I sprayed it with quick-drying auto-body primer, let it dry, wet-sanded, and repeated a couple of times til it seemed smooth enough and sufficiently sealed. Then I sprayed it with purple spraypaint, also from an autoparts store.
The primer is a lot more important than the paint that goes over it. The topcoat paint dries a lot slower than the primer. Don't use any primer that doesn't say "fast drying".
Having made various wood, epoxy, and fiberglass boat parts, I was thrilled with not having to wait for epoxy to cure. That fast-drying autobody stuff is a revelation for boatwork. Definitely good. Finishing the wing took less than an hour, including waiting. Joy.
After having subjected the wing to much exposure to water and mechanical trauma, I'm pleased that the surface is still good. Although the paint has worn off at the edges and is scratched a fair bit, The grain hasn't risen any and there are no visible cracks appearing. I'll definitely use autobody methods to finish wings in the future.
Malin Dixon writes:
"The Trampofoil wing is about 12 cm chord, and about 1.5 cm thickness. The section is
asymmetrical, and it is slightly concave on the underside, from about halfway to near the
trailing edge. The span is about 280 cm. It is extruded, with little end bits that only add
about 3cm to the span each. The wing is hollow, but there isn't much hole in the middle as
the wall thickness of the extrusion is about 0.5cm. The front wing is a solid extrusion."
The Aquaskipper rear wing has 91" span plus some little plastic winglet caps
that add 4" or so at each end. the caps fall off and it doesn't seem to make any difference.
Chord is 4.75" and the section is 12.8 % of chord thick(.608"). The section is similar
to a 63010 scaled up to that thickness, but it has a bit of hollow in the tail.
I haven't found that section in the foil library yet. The wing is a hollow aluminum extrusion with a web down the middle. The front factory wing is solid aluminum. It is 2' span, 2.42" chord, 12% thick.
Here's a flatbed scan of end views of the Aquaskipper Main and Canard wings.
Following that are some airfoil plots of other sections my designer pals like to use.
The bolt holes to attach it to the UPRIGHTS are 48" apart.
The foil section is a very crude approximation of the NACA 63013 section. I left the trailing edge square, truncating the section, just to make the trailing edge stronger. The bottom of this foil is mostly flat, also due to laziness. There are lots of foil sections that would work. Try them all.
Scroll down to see the data for Trampofoil and Aquaskipper wings.
I made this wing from a fir board. It was a shelf I had on hand.
It was about the right size, straight grained and knotless.
I drew foil shapes on the ends of the board and shaped it with full-length passes with an electric planer. I made some mistakes so the shape wasn't quite what I had in mind, but because of the full-length passes the section is pretty uniform from end to end. Having made tapered foils such as rudders and centerboards before I was amazed how fast it is to make an un-tapered foil. Joy.
After the planer I smoothed it with a disk sander then hand sanded it.
Then I sprayed it with quick-drying auto-body primer, let it dry, wet-sanded, and repeated a couple of times til it seemed smooth enough and sufficiently sealed. Then I sprayed it with purple spraypaint, also from an autoparts store.
The primer is a lot more important than the paint that goes over it. The topcoat paint dries a lot slower than the primer. Don't use any primer that doesn't say "fast drying".
Having made various wood, epoxy, and fiberglass boat parts, I was thrilled with not having to wait for epoxy to cure. That fast-drying autobody stuff is a revelation for boatwork. Definitely good. Finishing the wing took less than an hour, including waiting. Joy.
After having subjected the wing to much exposure to water and mechanical trauma, I'm pleased that the surface is still good. Although the paint has worn off at the edges and is scratched a fair bit, The grain hasn't risen any and there are no visible cracks appearing. I'll definitely use autobody methods to finish wings in the future.
Malin Dixon writes:
"The Trampofoil wing is about 12 cm chord, and about 1.5 cm thickness. The section is
asymmetrical, and it is slightly concave on the underside, from about halfway to near the
trailing edge. The span is about 280 cm. It is extruded, with little end bits that only add
about 3cm to the span each. The wing is hollow, but there isn't much hole in the middle as
the wall thickness of the extrusion is about 0.5cm. The front wing is a solid extrusion."
The Aquaskipper rear wing has 91" span plus some little plastic winglet caps
that add 4" or so at each end. the caps fall off and it doesn't seem to make any difference.
Chord is 4.75" and the section is 12.8 % of chord thick(.608"). The section is similar
to a 63010 scaled up to that thickness, but it has a bit of hollow in the tail.
I haven't found that section in the foil library yet. The wing is a hollow aluminum extrusion with a web down the middle. The front factory wing is solid aluminum. It is 2' span, 2.42" chord, 12% thick.
Here's a flatbed scan of end views of the Aquaskipper Main and Canard wings.
Following that are some airfoil plots of other sections my designer pals like to use.
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Aug 28, 2009. 10:46 AMkaiwilliams
says:
What made you chose one profile over another?
Reply
223
Sep 2, 2009. 3:01 PMTimAnderson (author)
says:
A section with no hollows in it is a lot easier to shape. If the trailing edge doesn't get too thin, it's less likely to break or cut you. There are other concerns like lift/drag ratio, stall speed, etc. which you can estimate with xfoil or other utilities. I didn't get too concerned with that. I just wanted something strong and easy to shape that was similar to foils on the commercial unit. It turned out to be good enough.
Reply
3
Jun 4, 2007. 10:04 AM
zmatt
says:
zmatt
says:
So did you basically just sand down the board to closely match the airfoil? I was thinking about building a hydrofoil boat powered by a 55lb thust trolling motor, do you think that would work at all?
Reply
223
Sep 2, 2009. 2:59 PMTimAnderson (author)
says:
yes it would work! Just make sure your wings are big enough to get to liftoff at a speed your motor can achieve
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