NOTE: Some of my files got corrupted. They will be posted as soon as I can recover/recreate them. Photo's too.
This is a working land yacht powered by a rigid wing sail. It is controllable by either 2 RC servo's or by free sailing.
The goal of this project is to create a working demonstration for students to print out and explore the physics of airfoils. This uses a NACA0018 Airfoil as the wing sail. It is printed in 5 parts, glued together, and placed on the removable mast. One of the wheel sections has a GoPro mount attached for video recording.
The free sail version is designed to have two students on either side of a parking lot. One sets the sails and lets it go. The other student then catches the yacht and sends it back.
The RC version is fully controllable, full steering and 320 degree wing control.
The Wing Sail is 100% 3d printed in 5 parts, A more efficient method would be to print a frame and then laminate the airfoil with a skin, but I wanted to keep construction to a minimum.
The servo version will require, servos, a battery, a Receiver and a Transmitter. Both versions will require wheels, some nuts and bolts, 1" PVC pipe, CF mast, and line. I recommend 50lb (or higher) braided fishing line. The wheels are 72mm Rollerblade wheels, from amazon. I could have printed wheels, but they wouldn't be as smooth or durable.
Check the Instructions for assembly details. This was printed on a 200mm cubed volume printer. I apologize for the Metric/Imperial mix I have here, but it's sometimes difficult in the US to stay metric.
- Add a club footed Jib sail to help power the yacht
- Add a windvane sensor attached to an arduino. Since a NACA airfoil has a particular AOA it prefers, the arduino would automatically adjust the wing angle to match the apparent wind.
3- 1/4" 2.25" Bolts (for the axles)
6 washers for the bolts
3 Lock nuts
14 M4x30 bolts
20 M4 washers
14 M4 nuts
50lb Braided Line
1" (35mm OD) PVC pipe (2 8" sections, 1 16" section)
ABS/PVC glue, or PLA/PVC glue.
.210" 40" CF tube (http://www.amazon.com/gp/product/B000BRLLAA?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00)
2 .040" 40" CF rod (http://www.amazon.com/gp/product/B000BRF84U?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00) (Other material can be used here)
2 Turnigy TGY-4409MD Servos (https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=24578 If you open the page and let it sit for a while, they'll offer a lower price)
Other RC components are up to you, as they are proprietary to your system.
Print Out: (No supports are needed, airfoils need the minimum infill you can get away with, the rest 15% or so):
2 Side wheel sections, There are two files, one with and one without a gopro mount. They are pretty much identical otherwise.
1 Hull section.
1 Hull Tail section.
1 Naca18 TOP section
1 Naca18 Bottom section
3 Naca18 middle Sections
Free sail will only require the one piece front wheel section.
RC parts to print:
Front wheel section A & B. These are bolted together to make it steerable.
4 Top PushRodPlates
4 Bottom PushRodPlates
Steering swing arm
Sail Swing arm.
I had to apply Acetone ABS slurry to my prints to strengthen them Just mix scrap ABS and Acetone in a jar until starts to thicken a little bit, then apply it in thin coats. If your prints are holding together well enough (my mediocre printer doesn't like big prints), then you'll be ok.
After applying Slurry/Glue to the ends of the middle wing sections, press them gently together till it holds. You can insert the CF mast to help align the parts if needed, just don't glue it in. Do the same to the top and the bottom, gluing them to the appropriate end of the wing.
Glue the shorter PVC sections into side holes in the Hull. Then glue the side wheel sections to those tubes. Try to maintain alignment of the wheel sections. Prop it up onto something if you have to.
Glue the longer PVC section to the front. Glue in the PVC section of the Front wheel to that. Again, maintain alignment.
Bolt the Wheels into the Appropriate sections.
Bolt (and glue if you deem necessary) the tail to the Hull.
The Free Sailing version is almost ready to go now, check below for sailing instructions.
Mount the servos into the Hull. Run the cord through the opening, then slide the servo in. It's a tight fit, but they make it. Use the screws that came with the servo to bolt it in.
The 2 sided swing arm that comes with the servo has a bump on the top of it. Sand that off, the top surface needs to be flat. (My printer is not precise enough to print a swing arm that attaches directly to the servo). Drill out the first hole in so that an M4 bolt will fit through. Bolt the printed Sail Arm to the sanded one.
Do the same for the Steering swing arm.
Bolt the two parts of the Front wheel assembly together. The wheel should be able to turn side to side easily.
Note for the RC: It's best to attach the sail to the throttle control channel, and the steering to the Aileron channel.
Turn on the steering servo, and let it rest in the middle/neutral position. Place 2 bolts into 2 of the bottom steering plates, each. Place each of those on either side of the steering arm. Place the .040" CF rod on each plate close to the center hole, but not covering it, and then tightly bolt the top plate on, so that the CF rod will not move. Then place a bolt through the steering plate hole, and bolt that. The plate should be able rotate, and the Rod not budge in the plate.
Either hang the Chassis on a wall, with the front straight down, or rig it so the front wheel is pulled straight out from the chassis in the neutral/straight position. Using the top/bottom plates, bolt the other end of the CF rods in place, try to eliminate as much play in the steering as you can here. The closer the rods are to the 'axle', the better the steering will be.
Mount the Sail swing arm to the servo. In the full up position on the stick, the arm should be as close to the tail as possible. In the full down position, it should be as far away as possible. The total travel should be as close to a straight line pointing to the tail as you can get.
Slide the Mast up into the wing, and then place it into the Mast Hole in the Hull.
On the Wing, tie the line to the loop on the bottom of the wing. A Bowline should do fine, but any appropriate knot will work. The line should hang freely and not bind on the sail.
Run the line through the loop in the tail.
FREE SAIL: Set the angle of the sail by pulling in or letting out the line. Tie off the line to the cleats on the Hull.
Aim the yacht where you want it to go, set the sail so it's about 15 degrees off the wind direction, and let it go. Off it goes!
Run the line from the tail trough the end loop in the swing arm. run it back around the tail loop. Either tie a binding slip knot (two half hitches), or use the bowsie to adjust the line. The wing's tail should sit about 15 degrees off the center line of the yacht when the servo is pulled in tight, so you'll need to use the bowsie to adjust the line tension.
In BOTH models, leave enough line so the wing can rotate almost all the way around, it's design to travel about 160 degrees in each direction, beyond that, it won't be able to translate the lift into forward motion.