Hi everybody, hope the warmer weather is treating you all ok.
Been thinking about my next landyacht project and come to the conclusion it would be logical to make another FISLY mini. With all the great builds out there I am thinking of reeeaallly stretching my skills and building a Y frame mini 
. My question though is this; what size and section steel is appropriate for the axles?
Looking at most of the Y frame minis around I see that they have larger dia, round tube, and it has me wondering whether people have found problems using RHS. I know I should just bite the bullet and go with my gut...but the time I have to spend in the shed is so limited I don't want to use it building a lemon 
Any discussion appreciated 
Interesting that you are considering building a y frame mini Lachlan
Can I ask what your reasons are? Other than they look cool or I havent done one of these yet sorts of reason which are valid enough I suppose
Funny, I've been thinking the same thing. But I reakon it's because they look cool. The gut feeling however is that it will likely end up heavier than a standard tee. Although seeing Paul's results from the weekend, it might not be the case!
Ah, the reason:
A swept axle design would produce a shorter seat/capsule which will fit in a Toyota Yaris hatchback (although the axle sweep angle could be relatively small (~20 degrees) to achieve this, my gut therefore told me 30mm axles should be ok). This assuming I keep my "bull-nose" seat designs that I like, which I want to.
I just thought I'd throw the question out there in case I attempted using a more conventional/larger angle sweep (eg: 45 degrees) for the axles.
I don't have a preference re. the looks of T vs. Y frames, each have their atributes 
If your sticking with the 30mm square then probably dont sweep them more than 45.
yes we have been using bigger, usually higher tensile tubes, but you could try experimenting with some of the narrower Galtubes ,of the same typesas the fencepost mini spine tubes.
SOS come in at a whopping 39kg!!!!!!!
^^^^ They appear to be good for spin outs, two wheel stunting and being French and cool, but there was no speed footage.
Correct me if I am wrong, but wind powered speed is what most of us here are looking for, n'est pas?
Another French Y frame miniyacht - Less angle than the Sailkart and aluminium axle tubes
Thanks for the info/ideas. The french designs look, how do I say this politely, complicated (which is more a reflection on me than anything else). The sailkart has too high CofG, and pilot sits too far forward, plus those flexi axles don't look like steel 
. <45 degrees sounds good, thanks for the info. Will take a look at the gal-tube sizes next time I'm at the steel depot.
my suggestion would be to build the seat then Y it under the knees as shown with Paul's seat and my seat, keeping the bottom of the seat level with the bottom of the spine
In the first French video, the black wheels were the cheapie Chinese ones I spotted in the garden centre a while back. Looks like they are working quite well...
. <45 degrees sounds good, thanks for the info. Will take a look at the gal-tube sizes next time I'm at the steel depot.
. <45 degrees sounds good, thanks for the info. Will take a look at the gal-tube sizes next time I'm at the steel depot.
Yes, that is right, They work well and depending overall load they might need a solid core turned up out of timber/lumber to fit internally to take out a little flex. They do seem quite hardy and help with the comfort of the ride. I think it is advisable to a piece of broken mast inside at the Chassis mounting end to protect against crushing when they are clamped in place.
Ron
no worries just give us a call. I find most people that contact me are mainly concerned about seat construction, you've probably had a few contact you by now (please encourage them)
One of the things I've noticed is some people having built a mini are ready to try something larger that has plans but maybe not as large as a class 5 or a class 5 that isn't a OTT . with this in mind a interesting design challenge might be a fixed class that would have the advantages of interstate racing knowing that your yacht would be equal and it is up to the pilot to win (like a laser or hobie 16 in water based sailing) I'd suggest Y frame with nasa mini class 2 dimensions(that way a windsurfer mast can be used and steering adds that extra dimension to construction) and no I havn't forgotten the Blokart- people in this part of the forum I feel are into building and sailing/racing a yacht they have built so this discounts the blokart. The club 88 comes close but is a class 5 with the associated costs and I believe a under slung Y would have more appeal, the same going for the promo. I seem to recall someone asking about class 5's recently (maybe Lachlan)like I did a couple of years ago and found it hard going getting the relevant information
Ian
Just a quick question for the ones with a mechanical mind, With a square tube inserted into another square tube (like a LLMini rear axle) is there any advantage or disadvantage to have either a horizontal of vertical hole for the locking / positioning pin?
There would be the ability to do either, and the hole would be at least 100+mm from the end of support tube section.
Only thing I can think of is if it is vertical and inserted from the top, there is less chance of it coming out when sailing.
Any differences in strength would have to be minimal.
all my square tube chassis ended up having a double sided Pop out fitting to hold it that was horizontal, then a rear fitted locking bolt that held the axle firmly in alignment. the stainless pop out is a riley product that was a perfect fit. i will do photos tommorow
Thanks grlynch for the info.... and I assume the more in the horizontal centre the better, as this would be a "neutral" point.
Next question to the 'Y' yacht builders what is size and materials being used for the rear axles... Carbon Fibre round tube, snow ski's steel round tube [size?] any others?
Any thoughts on 45 x 45 x 1.6mm or 40 x 40 x 1.6mm Square Galv tube for 'Y' rear axles?
keep in mind when the axles get bent it always bend up AND back. the problem is a shock load when you slam down off 2 wheels.
forget 1.6 mm wall for this exercise, go up to 2mm.
do they make a 40x40 or a 45x45,somebody needs to make sure. I suspect it jumps up to 50mm
I think there is a round steel galpipe around 40mm(galtube plus by steelmark?)
Ive used 40mmx3mm T6 ally before, but it became hard to get, and tends to fail regularly with a good bash
One of my local Steel supply places had the "Orrcon Steel" range in stock.
Yesterday I had in my hands on 20mm inside 25mm inside 30mm inside 35mm inside 40mm inside 45mm inside 50mm Square Galv tube. The tube thickness was 1.6mm and they all fitted SO nice, 2mm just doesn't work with the telescoping sections as the slightest inperfection in the tube just jambs things up.
There is a 40x40 in a range of thicknesses, (good refernce here with prices earlybirdsteel.com.au/rhs/rhs-square-painted)
I an imagine there is quite a bit of horizontal force when the yacht comes down at speed, but i can't imagine this would be much compared to the vertical force, and you have to put a hole in at least one direction.
All being said theory is theory, real experience would normally take precedence.
