Forums > Land Yacht Sailing Construction

St 49 Wingboat

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Created by US772 1 month ago, 13 Oct 2018
US772
329 posts
13 Oct 2018 12:26PM
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I designed and built this winged dirt/iceboat about 10 years ago. I designed it under a box rule. About 7 of them were built in some form. In hindsight I wish I had made it a one design. I think it would of been more popular. The wings are interesting to design and build and fun to sail. They are also inexpensive because they are mostly made of plywood.

&index=19&list=FLKqJHJ2yH8UtL89rICpofSA&t=0s

US772
329 posts
13 Oct 2018 12:29PM
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US772
329 posts
13 Oct 2018 12:32PM
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US772
329 posts
13 Oct 2018 12:35PM
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US772
329 posts
13 Oct 2018 12:37PM
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The mainwing


US772
329 posts
13 Oct 2018 12:40PM
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The flap is a NACA 0015


Here is a wing with a tapered flap



US772
329 posts
13 Oct 2018 12:41PM
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The main wing tee or wing/mast step and mainwing control wheel



The fuselage covered in 1/4" plywood



angle bracket to connect the axle or runner plank to the fuselage





US772
329 posts
13 Oct 2018 12:45PM
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2 Angled brackets to connect flap index to flap



The mainwing sprocket





The flap pivot hinges that go in the middle. The square stock goes into the trailing edge of the main wing and the round rod goes into the flap



The angled receiver bracket make 2 each. The tee slides into these brackets





Flap control handle with spring loaded trigger to index into flap index. It holds the flap in place at various angles





The flap index. The drawing doesn't show but the index should have notches cut into it every 5 degrees to allow the flap to beheld in place at the those angles. Notches approximately 1/8" x 1/2"

US772
329 posts
13 Oct 2018 1:10PM
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US772
329 posts
13 Oct 2018 1:20PM
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US772
329 posts
13 Oct 2018 1:25PM
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US772
329 posts
13 Oct 2018 1:36PM
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US772
329 posts
13 Oct 2018 1:38PM
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&list=FLKqJHJ2yH8UtL89rICpofSA&index=19

US772
329 posts
13 Oct 2018 1:40PM
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US772
329 posts
13 Oct 2018 1:45PM
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Wing building series - 8 part series -

US772
329 posts
13 Oct 2018 1:56PM
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US772
329 posts
13 Oct 2018 2:00PM
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US772
329 posts
13 Oct 2018 2:02PM
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US772
329 posts
13 Oct 2018 2:02PM
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aus230
WA, 1618 posts
13 Oct 2018 8:23PM
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Thanks John, much applicated
Cheers
Vic

US772
329 posts
13 Oct 2018 10:03PM
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It is my pleasure Vic!

US772
329 posts
13 Oct 2018 10:45PM
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There are a few things about the design I would do if I were to make a one design. I like the wing profile with the tapered flap that is 16' tall or 192" tall. The axle could be around 12 ' wide and the wheel base for and aft about 14' long. I design the main wing to have a 20 % thick chord with the thick point at 40% back from the leading edge. The flap could be a NACA 0012. To locate the flaps pivot point on the trailing edge of the mainwing multiply the flap chord length by .095%. example 20.5625 x .095 = 1.95" . By locating the pivot point using that formula the flaps leeweard side lines up well with the mainwings leeward side when the flap is deflected at 20 degrees of angle. It also achieves a nice slot to.
Why slotted flaps work the best - aviation.stackexchange.com/questions/30960/how-does-the-slotted-flap-workhttps:

lachlan3556
VIC, 1058 posts
15 Oct 2018 9:58AM
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Great post! Thank you

aus230
WA, 1618 posts
16 Oct 2018 7:55AM
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Hi John , Is the rear axle a single strip of wood or is it laminated, I seem to remember from a post a few years ago that it was laminated with a curve built in.

US772
329 posts
17 Oct 2018 8:17AM
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Its 3 pieces of .75" x 10" with a curve laminated into it. I think if it was just for landsailing it could be flat.

lachlan3556
VIC, 1058 posts
2 Nov 2018 3:46PM
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Great topic US772. One question I have (among many...) is why do many of the US yachts use a wheel/chain/gear for wing/mast rotation adjustment and the Europeans use a spanner/rope system? Have you found advantages/disadvantages to either?

US772
329 posts
2 Nov 2018 1:55PM
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When you tack a soft sail into the wind it luffs. When you tack a solid wing into the wind it ossilates. It is searching for a direction to go. when ossilation happens it usually reults in the complete distruction of the yacht. You can't stop the ossilation! The chain and sprocket has no slack. A rope used as in conventional sheeting does have slack. Slack in control system = SUICIDE! Unless the wing is counter balanced. See Richard Jenkins Craft

US772
329 posts
2 Nov 2018 2:03PM
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Example mast limiter snaps because of slack. Wing mast osdilates game over. Sequence of events - going 78 mph on spar alone 1 boat hikes
2 let out mast limiter cable to stop hike
3 slack line starts instant wing ossilation
4 carnage


lachlan3556
VIC, 1058 posts
6 Nov 2018 2:52PM
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I remember watching that oscillation crash a few years ago, not great for the builder/pilot but very spectacular. Thanks for your insight on this topic.



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"St 49 Wingboat" started by US772