Non-welder looking for help and advice.

[Luke]

Only trouble would be 'weather helm' - the kite pulling you sideways.

Though, that could be used to your advantage. It is, afterall, how windsurfers steer.

The key would be to put the rider in exactly the right place, leaning forward would cause you to 'round up' -steer to windward, leaning back would cause you to 'bear off' - steer downwind.

It'd be a novel solution if it worked

 

[Luke]

Adding to the above, the steering of the rear wheel could be locked with a 'normally closed' brake - holding its position whilst you don't want to change course.

Activating either front fiddle brake would release the rear angle-holding-brake, allowing you to change direction.

 

[wheelchair andy]

Is the rider not strapped into the buggy, by a safety harness, Andy? Or... let me re-phrase the question several ways;;

Is it likely that the rider will have to release themselves from the buggy, during a ride, in order to abort?
Are you also saying that; if the rider was pulled out of the buggy, the kite would then drag the buggy (and rider) because of the proposed steering cables?

Most riders dont strap themselves into the buggy itself but wear a harness similar to the girl in the photo. But I WILL be strapping myself into the buggy and have the kite secured to the buggy rather than myself. Without leg muscles to help me, it would be near impossible to fight against the pull of the kite around my waist.

It's very likely that at some point the rider (me) will have to release from the kite to avoid something painful. In this case the control bar would have to be detached and released from the buggy (via the chicken loop). If there are steering cables connecting the control bar to the buggy there is the possibility that the bar wont be able to be released properly and therefore not completely loose power.

This, along with the possibility of getting tangled in cables, the complexity of the design and not even knowing if it's really going to work has me thinking that it might be better to go for the central steering lever.

Andy, can we just confirm the limits of your movement? eg Arms 100%, waist x%, legs x%?

The reason I ask is I wonder how much stomach/waist movement you have, as it may have a bearing on other possible solutions.

There is another arm-only solution that occurred to me, which is to rig the bar (above) to a forward/reverse joystick. Or for that matter a left/right joystick. With the left/right joystick you would have two ranges of movement - one to steer by swinging left, right, the other to control the kite, pulling in, left/right. Only rigging this up would prove whether you could control the swing of the kart steerage, against the force of the kite. The geometry to balance the forces might be interesting, if at all possible.

I smashed by lumbar spine at a pretty low level so have complete upper body control, but absolutely nothing in my legs at all.

That being said, controls requiring me to lean or apply pressure from my waist and trunk aren't really viable. Like I said, without the muscle groups in my legs to help, I can balance but fighting against a force isn't too successful.

New idea.

Turn the buggy round. the front wheel becomes a rear trundle wheel - leave it to it's own devices.

Fiddle brakes on each of the front wheels would give you steering ability, and would require much less force, as you're only dealing with actuating a calliper.

It still remains to be seen if you can squeeze levers whilst hanging on to the bar. At least with this scenerio you are within the realms that bike brakes were designed for

That's a pretty cool idea. Not sure if it's workable though for kiting, without being able to quickly steer wheels into a skid there's the possibility of the buggy tipping over. Also because the center of gravity is towards the rear of the buggy, having two wheels at the back provides more friction to stop the buggy being pulled sidewards by the kite. For paragliding, the reverse trike design doesn't work at all as on launch and landing I'll spend some time on the back wheels and having just one might lead to extra gravel rash.

 

[andypocock]

There's some good brainstorming going on here boys.

I think we have to be looking at the rod and lever idea or twin pushbike brake levers for steering. I like the twist grip in principle but you'd never get the force required [try holding the headstock tube of a pushbike and steering by twisting it - no chance. Likewise try stopping a bike by gripping the rim hand - again no hope but easy as wink with a brake lever]

I'm not convinced that steering with the brake levers on the bar is going to be so tough. Remember that with one lever pulling one way and the other pulling the other way you are really only balancing one against the other. Straight ahead should be both levers about half way and, ignoring the kite for a minute, caster keeping you straight ahead. To go right you increase the pressure on the right grip and let out the left.

I can't see that the steering forces involved will be that horrendous. We are looking at a pretty much bald tyre on a low grip surface with a kite trying to pull it off the ground.

Andy

 

[wheelchair andy]

I've been chatting about the possibilities with some people on a kiting forum and being able to release the control bar is a huge safety priority, so I think that kills the idea of placing levers on the bar.

One thing that did come up was having the push pull lever in the center but instead of it having a locking and release device like the railway switch, having the lever return to center by springs when ever I let go of it. Seems like a nice and simple solution, as long as it's able to keep the direction I want rather than being pulled off course by the kite.
It's also been suggested that any buggy design built have a roll cage fitted in case I cant release the bar quickly enough, as I'll be strapped in and likely bounce around on my head otherwise!

 

[andypocock]

Sprung loaded lever is good so long as you can manage the kite with one hand. You'll soon find out

I think the cables could be sorted even with the need to dump the wing in emergencies but why make things more complicated than you need to.

I'd get a standard buggy fitted up with a lever asap as a proof of concept. If it works out then comission your all purpose super lightweight flying / kiting buggy

Andy

 

[wheelchair andy]

OK, I just bought myself a buggy to experiment on!

Anyone interested in helping out and doing some welding?

I dont have a clue where to go from here, where exactly do I buy bits of steel from? What type/size etc should I get?

 

[jugs]

This all sounds like an idea that might fly

Where are you

 

[wheelchair andy]

I'm outside Edinburgh, going down to Leeds to pick up the buggy in a couple days!

 

[andypocock]

I'm not going to be any good to you Andy as I'm on the south coast but plenty of welding goes on north of Watford. I think that is how they keep warm.

Andy

 

[madkayaker]

I'm in Carlisle and it does help to keep warm but since Ive got a stick its hard to keep the rods dry! Cant be much help either I'm afraid but if you want light on it to indicate mirror maneuver I'm your man! (providing its 230V)

 

[jugs]

Sorry, but I'm in Anglesey, my nearest big city is Dublin
But we get a lot of hot gas & some flashing from north of Hadrians wall.

 

[knoba]

I think I may not have represented the last twist grip idea very clearly; so... here's, another one of my, crappy drawings (don't laugh! ...it took me an hour on the lappy to do this... ) ) for some better clarity;

View attachment Diagram1.bmp

Red = twist grips (each 180* rotation ...say!)
Blue - Casing (attached to loaded kite wires)
Black = take off shaft (with quick release interface)

*Only black & red bevel gears mesh.

It is only a simple diagram!

Having got that out of the way; sometimes it helps to forget it all, for a bit, and then come back fresh on it (I use this method a lot).

I'm also happy that the cables' ideas have been thoroughly explored. Discovery of design constraints has (I agree) lead to the lever idea as being the most simple & viable.

I'm not completely convinced about the force required to turn the steering wheel under differing loads. It would be good to know just how much force is required, or even, a way to quantify it.

I thought the best thing I could do, to help, at this point is reconstruct the design brief including all the constraints that have, thus far, been stated & discovered;

• Rider will be strapped into buggy.
• The kite is also secured to the buggy.
• The kite control bar would have to be detachable from rider & buggy.
• Buggy design must have a roll cage fitted (without fouling kite wires or control bar movement.).
• The chassis must be extended to support rider's legs.
• Total weight of buggy at around 15kg.
• Converted to use for paragliding (removable front end? Interchangeable wheels?).
• Buggy movement can be extremely energetic (anywhere from 3 to 0 wheels in contact, jerking, tipping over, jack knifing etc. Quantify G forces?).
• Lockable steering, but, easily releases when rider grabs the lever.
• Steering capable of full lock turns v.quickly.
• The lever design should not present a safety issue (hard, pointy, sticky out thing) NO Jugs! ...not now!
• Suitably rated for expedition across the sahara in March (heated materials in desert - hot metal - just how hot will it get? Any other considerations here?).
• The available wheel lock required, from L/H to R/H, has been established (90 degrees).

There are some questions above still to be answered. How much of a kite buggying purist are you Andy? Considering all the design constraints it may be worth totally re-designing the concept vehicle.

This may all be moot, as; you've already bought a buggy Andy. However some of the questions above are still relevant to you; particularly the hot desert sun on metal. Reinforced fibre glass or carbon fibre would be good options.

paul33 made a generous offer to help. He would be a good person to talk to.

I also thought that it would be a great opportunity for an engineering graduate to take up as part of his / her studies / thesis. Or maybe even you, using it, to get an engineering / design qualification, Andy!

Go for it!

 

[wheelchair andy]

I'm picking up the buggy on sunday hopefully. Still not sure what modifications to make, or how to get them done. So many things to take into account!

Made some progress with getting info on other wheelchair users kite buggying, as far as I can find out there's only one buggy thats been made for hand control:

http://www.mobiusonline.co.uk/kiteschool/disability.html

I got in touch with the guys who made it for some info and told them of my plans, just got this in reply:

Steering: We initially tried to have a joystick, as in your design, but the force to turn it when the buggy was stopped or moving slowly was a bit excessive so we bought a second hand 'teleflex' cable steering system (the type used in boats) and fitted a rubber boot from an auto parts store to stop sand getting into the cable. This worked flawlessly, and you could add one of those sweet chrome knobs that bus drivers and truckers love so you can spin the wheel with one hand. I'm sure a joystick as in your drawing coul work if the leverage is enough, but a small round wheel compared to a large metal stick seemed a bit safer on reflection.
Locking the steering sounds a bit scary to me, these things can pick up a hell of a lot of speed, as I'm sure you're aware, and the ability to quickly edge upwind is kindof your only good brake to slow down, same with the straightening spring thing - it was actually quite useful with the wheel, you could turn the wheel so the wheels were pointed one way and then move the kite with both hands to tease the buggy around until it was facing the right direction and then straighten the wheel before you got a huge power dive in.

Kite control: Having used the buggy with the steering wheel, I quite happily flew unhooked with my hand in the middle of the bar and we also used velcro ankle straps to hold wind/kitesurf harness spreader bars onto the frame of the buggy, so you could hook the bar in when you got tired. You can actually carve the kite up and down quite well with it hooked into one of these loops adn you can shift them forward or backward to affect how gusts hit the buggy (ie make it head up or bear away from the wind).

Frame: The three wheeled buggies are pretty stable, but we (the instructors) have flipped them on quite a few occasions, as this would be difficult to recover from, we decided that for this buggy we needed a more stable wheelbase that would be as close to flip-proof as possible. We cut off the front bearing on the three wheel frame and welded a stainless crossbar and supports onto it. Then we added pivots so the wheels could turn parallel (as in a car) and a tie-rod between the wheels. This was easily done using bolts, threaded rod etc. In my opinion, the four wheel buggy with a steering wheel was way more fun than the regular three wheeler (would you drive a reliant?!) although Timo was dissapointed as he couldn't show off to tourists with his 'two wheel' trick as on the three wheelers. Honestly, this thing was crazy, I spun it out at least 720 degrees and it didn't flip. Was like being allowed to have a go-kart on the beach!

As for building from scratch, we were pretty successful in using an existing buggy, in fact we didn't modify the back at all, apart from the harness hooks which were velcroed on. All we needed was an extra wheel and some work done on the front bar, I think we modified it in a day or so.

 

[knoba]

What a great find Andy! Happy days.

 

[wheelchair andy]

Stop Press!

I just got this link from a thread I started on a kiting forum:

http://www.viper-parakart.com/ (Click on the "Mano Masa" text link).

This is almost exactly what I've had in mind the whole time. I'd been thinking about a single central lever, but the side levers may well be better, and safer. They come with the danger of tangling the control lines when I fly the kite low though, so maybe the levers could be shortened.

Obviously this will mean less leverage to steer the wheel (a problem that the makers of the four wheel buggy I posted about before mentioned when they experimented with a lever), is there any way to add a mechanical advantage into the system to increase the power from a shortened lever?

 

[knoba]

On the www.mobiusonline.co.uk link; (you've v. likely already thought of this, but, I'll mention it anyway) It may be worth booking a lesson, or two, and taking lots of photos of the buggy itself, talk to the staff, and possibly interview the featured rider Heidi Thomas on possible design impacts and considerations etc... In the video clip; her bum seems awfully close to the ground (not such a problem on a flat surface, but, desert terrain...?). Also; a good chance to check out the beaches, Peranporth seems like an ideal spot as it is a beautifully long, flat, wide, sandy beach without too many off shore cliff formations. They sell organic ice creams there too which are rather nice (all in the name of research of course ). A great prototyping spot is worth getting to know. I take my transit van there, for surfing breaks, for weeks at a time.

Their current design for the buggy seems easy enough to guess, but, some pictures and feedback would all be to the good. It goes without saying that their buggy is going to be fairly heavy.

As for the Mano Mossa it too looks quite heavy and I would have thought that (as they've taken it to production) the leverage ratios and the effort required to steer the buggy has been optimised to give the best balance of control. Looking at their work (on some of the other pictures) is quite impressive and I wouldn't be surprised if their lever set-up was totally adjustable.

the side levers may well be better, and safer. They come with the danger of tangling the control lines when I fly the kite low though, so maybe the levers could be shortened.

They don't seem to think so. It must be well used and trialled.

I still think you're best bet is an interview with Heidi. Experience is going to account for a lot here. Keep looking for alternatives, show your research to her, and ask for opinions on them.

What you are doing is fairly standard procedure (and quite a bit of fun to be had) when developing any new idea. I must say though; I'm very impressed with the thoroughness of your research. Well done chap!

 

[wheelchair andy]

I've asked for some more detailed pics of the mobius set-up to get an idea of the mechanics and workings, they're down in cornwall and I'm up in edinburgh so I'm not going to be able to physically meet up with them until well into the new year unfortunately.

I'm trying to find out more about the teleflex cable systems, I'm begining to think that I may be able to marry the two systems together. Having the side levers as in the picture above, but instead of solid bars turning the wheel having the teleflex cables connected. If this means less power is needed on the lever to turn the wheel it might be the solution, I'd really like to have those levers a little bit shorter if possible.

 

[knoba]

Could you email Heidi and send her some of the designs? She would be an enormous advantage / asset to your research!

I'd have thought you would be able to shorten the levers without a noticeable impact, since, you have a much greater upper body strength than most.

 

[andypocock]

Hi Andy

I've used the teleflex steering on many boats over the years and I'm sure it could be used here (it has been!) but there is no way you will ever have a dual purpose buggy. The weight of the system, brackets and steering wheel will see to that.

It would be interesting to know why the other guys went for twin levers. Is it just so that you had the option of steering from eith side or did they feel it was a two hand job?

You certainly have more chance of building this design down to a weight.

Andy