While trying to find a site that sells sails for my sailboat I ran across another toy called an RC Sail Car and decided I could probably build something similar.

Off to Lowes for some PVC pipe, some odds and ends and then to the LHS for a sail winch servo, a couple 4 1/2" wheels and a fultz steerable fork and other odds ands ends.

Sail will be made of ripstop nylon. Still have to mount the nosewheel servo, cut and rig the sail, but this part was done in one evenings work.

The design is setup to break down easily and fit into a sail bag. The rear wheels will break free in a collision and the mast is removeable as well.

These should be great fun to race! Attached files

 

Sail cut and rigged. Still trying to find the right size battery to fit into the PVC. I picked one up from the LHS yesterday but discovered the voltage (6V) is too much for the AR6300 receiver I used.

My only 4.8V battery is just a tad too wide to fit properly but I was able to wedge it in for a test run.

Of course, by the time I was ready to give it a run, the wind had died to 3kts and although it did with a gust, go about 10 feet, for the most part it just sat there begging for wind to fill the sail.

Rigging the sail was a bit of a challenge. I used a drum winch servo and ran the line back to a post, around the post and back to the drum to complete a loop that maintains tension on the line at all times so the line will not be able to drop off the drum.

I added a spacer 18" forward of the rear most post and then tied a line thru the spacer back to the rear of the PVC and attached it to the drum line and the other end to the boom on the sail.

Operating the drum moves the line 17" letting out the sail or pulling it in tight. At worst case, I could have 15" of line dragging on the ground if I were to let out the sail fully with no wind, but at least there is nothing for it to get tangled on and operating the drum winch will easily pull the line back in.

We have have wind out the whazoo lately and it would have been perfect had the sail car been ready yesterday, but now I guess I have to wait for the wind to return to see just how well it will work.

I need to find out whether or not I am going to need to add brakes.

Anyway, here are a couple of photos of the nearly complete PVC Sail Car. Attached files

 

Brakes are the one thing I wish I had installed on mine already. With my 1M main sail (no jib) RC land-yacht, and a nice gust of wind, it will jump to 30 mph within 3 feet. The only option without brakes it to turn upwind without gaining too much speed in the cross-wind tack, then dump speed as I'm coasting upwind, without running out of parking lot.
I need brakes, and so will you.

 

How cool! I had no idea anyone else here would have one of these. It has been a fun project. The rear wheels are designed to break away so adding brakes there is probably out of the question which leaves the front wheel as an option or maybe a drag stick.

I think a servo operated drag bar would be the easiest to implement. Not sure where I am going to find room for it since I didn't plan for it up front.

 

The winch servo rotates 3 and half full turns per full stick movement. It is connected to the throttle servo on your receiver so that it can remain at whatever setting you move the stick.

It takes a couple of seconds to make the full 3 and a half revolutions.

You have to be able to keep some tension on the line so that it does not fall off the spool, or you would have to put some kind of cover on it or maybe just something to rub against the drum to keep the line from coming off if you don't tension it.

You can adjust the end points on most transmitters to control the number of revolutions if you don't need the full range.

Here is a link to the servo... http://superdroidrobots.com/shop/item.asp?itemid=600
and a cheaper one... http://www.himodel.com/radios/GWS_S125_1_2T_Double_Ball_Bearing_Sail_Winch.html

 

Might be overkill for my needs. I discovered that a $3 TG9 servo will fit between the forks of the steering assembly.

I can probably cut out a servo extension from some bakelite material on the phlatprinter and rig it to pull against the side of the tire to slow it down.

Might even be room for 2 servos. Then I could put them on a Y harness and have the servos clamp the tire from both sides to effect a poor mans disk brake .

Just need to figure out how to mount them being as the servo mounting holes exactly match the width of the fork and there is no way to put the screws thru them to bolt them in place.

 

Why not emulate a bicycle caliper break with a single pull cable?

 

Excellent idea. I thought about that. In fact that is what led me to checking to see if a servo would fit between the forks on my steering piece.

It would a bit more complex I suppose as I would need to mount the servo in the fuse and run a cable to the mechanism which I would still have to figure out how to mount on the forks.

The servo mounted in between the forks with the arm scraping the tire seems to be the simplest way to accomplish it but I like the brake caliper idea.

Thanks for the suggestion.

It is cold and rainy here today. Kind of zaps my energy or desire to even go out to the shop so maybe I can work up something in SU to try.