So I've been hard at work designing a buggy and I think it's time the design got some scrutiny from Buggyers. let me know what you think.

http://www.youtube.com/watch?v=DIYOrT_vJXA&feature=youtu...

I'd be particularly interested to hear what people thought would be appropriate for the material for the frame. I really don't have any idea where to start as far as pipe diameter and wall thickness and without that I can't calculate how much the thing is going to weigh.

Thanks,

Skye

Looks like a fantastic project! With the roll bar behind your head, I'd guess you'd have to make sure you can't be half pulled out of the buggy and then smacked in the back of the head by the bar. Or if you did you go A over T, which bit is going to impact the sand first....

I'd love to build one of these myself (although I think I'd have to acquire some serious new skills....) so please keep us posted on this project.

This looks pretty compact side to side. Maybe its not. Get as wide a stance as you can as when you are heading down the beach there is a lot of side pull on the buggy. The typical buggy's triangular stance if fairly stable. you've moved it to where the base of the triangle is the pull point which will want to bring it over easier. i just know most of the time when i have an OBE its out one side or another.

This looks like a great build to work with. I agree with Mike about moving the front axle out further. Every thing will still work about the same but it will put your weight further from the down wind tires. Also if you can find those axle studs in 20mm it will be easier to get rims and bearings. Though 3/4" is what Van at VTT was using so you can contact him about finding the right bearings.
This is a great idea and I commend you on this. It's a good idea to post more here as you advance so you can get input from more nut cases like us!!
Best of luck with the project.
Dave.

Cool SW model! I dont know much about buggies, but why make it go sideways?

As stated by the fine gentlemen above moving the wheels farther out in the direction your eyes are facing (as opposed to the way your ears are facing) , will improve the "outrigger" stability. Also saucer shaped skid plates or big caster wheels mounted beyond the main wheels to function like "anti tippers" may be useful. A little bit of wheely action is fun and exciting but faceplanting a heavy buggy with bar and lines trying to slice and dice your face ( because thats where they're going to be) is something worth a little extra effort to avoid. Got to say , you put together the coolest presentaion of an idea that ever hit the forum!

Right on Skye!
You should be an engineer! Even Julie's impressed!

Anyone else have any thoughts? More the better.
How bout from some of the guys that make their own buggies?

I'ved send a link of this thread to KC04 he build is own crab.

I built a replica of Crab Buggy proto # 5 and I hope going October at Wildwood

You did a nice job on the buggy Georges. Takes a few rides to get used to the steering, it was fun.

Thanks everybody for the input. I will make a video explaining changes I made asap. @filco is that a shock on the rear wheel? Do you think I should put one on?

i'm from italy.

This is my second crab buggy homemade.

here the history of the building

http://www.foilforum.it/covo-smanettoni/blog-del-crab-t4671....

ciao pat

here a little video of my first crab buggy
http://www.youtube.com/watch?v=kbZLWuTdQ9Y

this is the second seat for my kids

http://www.foilforum.it/covo-smanettoni/sidecar-porta-pupi-p...

Ive got another video about the buggy! I had to move it to a different thread though to do a poll. Here is the new thread...


http://www.powerkiteforum.com/viewthread.php?tid=26773#pid25...

sorry for my google translator english :-).

I think there are 2 things wrong in your project.

1) shock absorber built so it does not work, the wheel tilts and does not go back. I tried.

So instead it works very well:

http://www.foilforum.it/covo-smanettoni/lenticolari-sospensi... (see the 2nd photo)

It's a parallelogram suspension.


2) why build the wheels upwind ? could tip over down wind.
With the wheels down wind, instead, it works very well.
A little video:
http://www.youtube.com/watch?v=cfimGWY4B6E

riderpat,

We ended up ditching the shock version for a few reasons the main one being that the pull of the kite would tend to unload the shock absorber and make the buggy feel like it was pitching forward. It is also probably unnecessary as I will be using the buggy at a dry lake bed or on a flat beach most the time. Also it just makes it more complicated. I think if you were going to do suspension it would almost be better to go with less travel to minimize the pitching forward effect but still have a little absorbance from bumps. I did look at your parallelogram suspension drawing. If I did do another one with a shock I would probably do something like that.

The main reason I had the wheels behind the steering knuckle is so that the wheels always tend to straighten out or go to zero if the steering is let go. I wanted to be like a bicycle where if you take your hands off it tends to go straight and not be floppy. I actually copied the geometry from some plans that I found on the Internet. The other reason I am partial to the bar being forward is because it makes it really convenient for transporting. we will basically roll this thing up to the back bumper on my van, then lift the rear of it up to the rear windows and all the wheels will go off the ground.
I do plan on experimenting more with flipping the wheels to the other side though and I will probably do that if the steering can be as stable as this way. How well does the steering on your buggy work? If you take your feet off of the footplate while traveling does the buggy tend to go straight or turn radically? The steering is very important to me.

The buggy flipping is much less a concern than it used to be I think the plan now is to bring the center lines down to the frame in front of the center of gravity (around the knees) and not through the bar so if the kite pulls it tends to drag the buggy as opposed to flip it.

This is an animation I did to help generate support for the project,check it out:

http://www.youtube.com/watch?v=qQdfIBgNj28

Great project you've got going on, The videos are great and a learning experience as well.

So here I sit thinking about the designs and I started thinking outside the box so to speak and I asked myself, Self... why do crab buggies have to steer with the front side 2 wheels?????

It looks like a lot of linkage and mechanicals to make both wheels to steer.
Why not just steer the rear wheel? Simple? Looks that way to me. After all we steer regular buggies with one wheel!

You could use shocks on each wheel on the front side and possibly get a better ride, reduce the mechanicals of 2 wheels steering and lower the over all weight.

Just a thought or two about one.

Absolutely on the learning experience. I can tell inventor is going to come in handy for so many things. Steering with the rear wheel and having the front two fixed wouldn't work, the front wheels would just stay going straight and the rear would just lose traction and skid rather than turn the buggy.

If anybody wants to follow the project, I will be posting here: http://thespidercrabblog.blogspot.com/

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Have you talked to the French guy who made a few really nice crab buggies a while back? He was using them onthe beach in Morrocco. He's super helpful and I could dig out his email if you need it.