Heres a cropped version of your diagram, I didn't change a thing in the design just deleted the space in Paint.



The design looks good to me. Not that i know much about LY design but from what I can see it looks good. I definately support the unconventional aspects

May i ask how dedicated suspension, like the mentioned leaf system, would be incorporated?

EDIT: if you want to replace your image i'll delete the one in my post just to neaten up the thread.

To crop the image

- I simply dragged a box around the desired item ('box' icon is at the top left of the tools menu in my version).
-cut it out (ctrl+X)
-opened a new canvas and set the canvas size to 5 by 5 (exact size is not important)
-paste the previously cut image there and say 'yes' to the prompt asking to increase canvas size.
-save the image as a JPEG, GIF, or other format you like and your done.

Hope that helps you out. As for the suspension notes Im always very interested to hear about developments. I see the use of car wheels is limiting my crafts performance to a degree (I guess) via the mass increase. I haven't looked seriously at suspension as the mechanisms required for it are heavier than the car wheels because Im limited to working with steel, or too complex/expensive/experimental/etc.

I'll be keeping an eye out here waiting for more on this build. How close do you think you are the some metal morphing?

Here is another variation for front suspension (Bill Finch Design).
A long length of bungee cord wrapped around the main spine and front end.

Hey all.

Do you think the problem landyacht highlighted could be solved by mounting the seat on a cussioned mount, say a rubber object that soaks up some of the bumps? It works for cars.

I must say the front suspension looks impressively elegant, i like the use of curves. One problem though may be the keeping of wheel allignment as the suspension is worked under spring bias, as in a corner. A very stiff axle/spring union may help reduce this, I dont know. Someone else may have an idea too.

The rear suspension is elegant also although i see a (potential?) problem. As pressure is applied to the rig it will be loading the leeward (?? the downwind side) spring much more than the windward spring leading to an unlevel ride, not that this should cause too much of a practical problem if the pilot doesn't mind.
More of a problem is the suspension rates under load. I'll try to explain with an example. Here goes .
As a landyacht sails and turns through 360 degrees to the wind at various times we have to assume the rear springs have the same properties. The windward spring we will say is sprung so that its wheel is working with optimum suspension characteristics. This however means the leeward spring will most likely be fully compressed (my brain judgement/guestimation) as it is under pressure from the rig.

Just for interests sake I was thinking of using a similar system (though more like a swing arm setup using coil springs i.e. motorbike shocks) and attach the mast stays to an appropriate point of the swing arm. The springs are sprung so that suspension is provided to the leeward wheel under rig load (i.e. sailing with rig pressure on the leeward wheel), there is no tension on the stay under these conditions (there maybe but thats explained later). The windward wheel also has correct suspension character because the overload is cancelled out by the tension force provided by the stay (which is proportional to the pressure applied by the rig). There may also be spring loaded stays to provide more proportionate suspension activity, to the leeward wheel in particular.

Have I lost everyone? I'll try to get a pic up to show graphically what I mean in case my post is as clear as mud.

Evening all,

Kody, you posed the question of drilling through steel spring material.

I am assuming you mean the difficulty drilling posed by the nature of the steel when using standard HSS drill bits?

A "Cobalt" drill bit run normally or a little slower with coolant/oil will very nicely drill holes in spring steel, bisalloy and other similar products, that have been or are hardened or have work hardening properties (stainless steel, bisalloy etc. etc.)

Many years ago in the town where I live (and before I was born or was very young) a fellow had a LY, the entire rear beam of which was a single very large leaf spring. This craft was apparently huge, around 20 feet long or more, and width in proportion.
I believe Gizmo knows of this craft and its owner.

Lachie, as you, I have toyed with the idea of a suspension LY because of rough paddock ground. Systems I have drawn are based around what you may find on an open wheeler race car, pushrod bellcrank. Damper unit laying down and longitudinal, another with damper laying down parallel to rear T axle, a thing similar to Kody's using mounted leaf at each end and a design using torsion bars (ala Chrysler, Valiant)

Somewhere on the net there is a grainy photo of a bloke in a LY with rear suspension, where the (coil over) spring damper units are mounted at an angle around 45 degrees.

I have completed an amount of research re coil over units, availability, cost, what/not to use etc. If you go down this path I may be able to save you some time with info later on.

My drawings have not been committed to CAD, they are all pencil and paper (beer coaster) at present

sorry if its a bit simple
KISS

Yeah, this is great!! With this shared knowledge and experience I can see Australia being the world leader in landyacht technology in the not too distant future. Keep up the great work!!

My only concern with the rear leaf springs in Kody's design is I think you'd need something to stop them from twisting under load due to the flex in the spring, thus causing the alignment of your rear wheels to go out.

As Tommy Cooper used to say,
"Just like that"

landyacht said...

with the axles coming out from under your head you will feel evry bump you go over, thats one of the reasons we started to sweep the axles forward. Check the cl 5 specs in the articles section regards suspension

Hi Paul,
You have lost me completely with the above comment. You replied that you swept the axles forward. Do you mean that you swept the axles backward?

I am leaning heavily towards the forward sweep axle style. It offers great benefits in easier construction. Checking over the design rules, a tubular stay can be added from the wheel to the near the mast. Tube seems to be a legitimate form of stay but not a cable. I still remember the Vampire jet that severed a girls legs dragging a steel cable at low level along the beach at Sale. Big diference though between 400 knots and 60 kph but the potential is still there. I saw where two people have been hit by a S/Y and one was killed.

It's very interesting to develop suspension and many super idears have been submitted. It's wonderful to see so much knowledge being shared. However, the biggest drawback with the idear, no matter how well designed, is the extra weight. Suspension is great when running in a paddock (or grass airstrip ) but not in an important race or any sponsered event (IMO). Every extra gram mass sucks out the available energy to accellerate etc, something about physics.

Kody

Kody said...
I saw where two people have been hit by a S/Y and one was killed.

Far out, where did this happen?

Possibly, suspension systems would be most suited to hybrid LY or larger classes with more sail area/wings when "racing". Unless using anything but very exotic materials, a Class V (min 50kg, 5.5m sail) or similar performance craft, when raced in class, would possibly be uncompetitive with the increased mass. The class rules also regulate material type used in construction.

By hybrid I mean, say a Class V chassis with suspension and slightly larger sail (overcome inc. mass) for paddock or non racing.

It goes with out saying, there will always be a weight penalty when adding systems for comfort and/or performance. As Paul stated the trick is design with maximum strength and minimal weight.

Lachie, another thing I drew up was a system akin to the early Mini, that being basically, a rubber ball/solid sphere into a cone.

hills said...

Yeah, this is great!! With this shared knowledge and experience I can see Australia being the world leader in landyacht technology in the not too distant future. Keep up the great work!!

Not meaning to burst your bubble of enthusiasm there Hillsy but I think the yanks have been at this game a bit longer than us and have come up with some sexy s**t.

The photo is of one of the Sirocco models. Go to "www.windline.net" and click around to see more sexiness. Cheers Cisco.

No secrets Lachie,

might just be a bit wordy if no one is going to use directly.

In a nutshell, MTB units too expensive, if use cheap versions, are exactly that, cheap, damper does not work only spring. Pit and other mini bike units in same vein.

Motor cycle units available from (new) $160/pair, 285mm eye/eye. Also available at wreckers. Adjust for bump and rebound in damper, adjust spring stiffness (wind nut up/down). "Industrial Springs" (SA) will supply replacement springs at VERY reasonable cost. Depending on terrain, craft and crew weight, you may find you need an 600lb, 1000lb or 1500lb spring etc.. Will make spring to your specs. That is, poundage, rate (single, variable), length etc. etc.

Mass of m/cycle units is only a few kilos/pair. As you construct mostly with steel and for rough terrain (strength) this may not be too restrictive.

Hey Cisco, that image of the Scirocco is better than the grainy one I mentioned. How heavy would that craft be? How much sail area? And with your super size me 125+ kilo Yank on board, you possibly could not run that thing anywhere but on hard made surfaces.

Kody you may be a big fellow here, but stateside you are an average man.

You've both got that right. On the Sirocco site the specs of that machine were well over 50 kg.
It is definitely a different breed from the Aussie class 5 greyhound.

A bit like comparing a Chevvy Belle Aire to an FX Holden.

cisco said...
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When I look at this suspension combined with the MC style front forks my sense of sailing tells me that when the suspension leans heavily to leeward the front end wouldnt track straight and would want to pull to windward. perhaps this is why they only go 70.