Y frame Ski Mini

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Clemco
Clemco
430 posts
430 posts
29 Oct 2010 11:30am
It's about time I got back into building mode again. Almost got all the parts I need. This one will be to the new FISLY mini rules.


I will be going for lightness to make it airline luggage frendly. 25kg all up is the goal.

Just need to get some of those nice light plastic wheels. Hope to weld something up this weekend.
Gizmo
Gizmo
SA
2865 posts
SA, 2865 posts
29 Oct 2010 5:52pm
Most of the yachts you seem to build are "Y" frame, What is the reason you choose this style of construction rather than a straight axle yacht? ["T" Frame ]
And what are the positives and negatives you see of the "Y" Frame.

[Just asking a question that newcomers to the sport might be thinking]
landyacht
landyacht
WA
5921 posts
WA, 5921 posts
29 Oct 2010 5:25pm
you notice the difference when sailing over really rough ground, the Y frame tends to float But of course you have to now tune the chassis to the pilot a lot more.
Remember hiko found clemcos Y frame almost unsailable as it was tuned to clemcos weight. if you build too flexible it could slow you down , too stiff and the yacht might tend to suddenly trip over itself . Y frames on minis are really science by experimentation. Kind of landsailing cutting edge art We havent even started trialing any OTT chassis's yet.
On a smooth surface , like lefroy a Y frame might not give you an advantage, then again it might................
note the high degree of mights, maybe's and possibly's in this post
Clemco
Clemco
430 posts
430 posts
29 Oct 2010 6:03pm
Y the Y frame? It's all about balance. Once you loose your balance when sailing a landyacht you automatically slow down to regain control. With the Y frame all the forces are spread evenly over the triangle of the footprint. It also gives the yacht longer legs which can store the power of the wind as they flex in the gusts and release it in the lulls. The only reason the skinny axle minis were hard to sail in a straight line was because the legs were flexing forward and aft as well as up and down. That is what I hope to correct with this build.
Hiko
Hiko
1229 posts
1229 posts
29 Oct 2010 6:31pm
Clem can correct me if I am wrong here but there was two skinny y frame chassis
built A very skinny one and a just plain skinny one
I never got to sail the very skinny one Clem can comment on that
The skinny one I found not too bad downwind but a real handful upwind scary even
It wasnt helped by the stiff steering which made for jerky oversteering by me
anyway
Clem I think managed it OK but he is a lot lighter
Clemco
Clemco
430 posts
430 posts
30 Oct 2010 5:10am
Yes, there were two test runs with the skinny, I will call them legs. The first ones were 31mm fibreglass tubes with a timber dowel epoxy glued inside. They were very flexable. I liked the way it heeled over but the flexing was also 3 dimensional which made the yacht start swaying back and forth in the horizontal plane. I ended up spinning out after only sailing a 100meters or so. The second legs tested in the same frame were plain galv steel water pipe. Slightly larger 33mm od. They were the ones Hiko sailed. They suffered the same problem but nowhere near like the fibreglass ones. What I am aiming for with this new one is to get the heel effect without any forward and aft flexing.
Clemco
Clemco
430 posts
430 posts
30 Oct 2010 5:52pm


Here's my simple welding jig for the Y frame channels.

The main spine neatly fitted into the channels ready for welding tomorrow.
Nikrum
Nikrum
TAS
1972 posts
TAS, 1972 posts
30 Oct 2010 9:36pm
I just love it When you Boffins talk dirty

This is what I like to hear and see experimentation and Thinking outside the box. Good stuff lads
Funny A couple of days back I was talking about to an acquaintance about the SR71 Blackbird and later got to thinking a cross bread Blackbird and Land Yacht. Hmm
It wouldn't really be about competing just fun and aesthetics. just cool fun.
Anyway playing with design and materials available is really good stuff and as much as I don't like admitting it Aussies can be Innovative.

I want to hear more dirty talk [}:)]
Ron
Clemco
Clemco
430 posts
430 posts
31 Oct 2010 2:25pm


Got the main frame almost welded up today. Those skis do have a nice spring to them.
Hiko
Hiko
1229 posts
1229 posts
31 Oct 2010 3:19pm
Do you think clem that the angled frame /ski junction point may introduce a twisting effect as the skis flex ?
Clemco
Clemco
430 posts
430 posts
31 Oct 2010 6:50pm
How can it? as it is on the under side of the ski. I will have large washers on the nuts when it is finished.
Hiko
Hiko
1229 posts
1229 posts
1 Nov 2010 3:40am
Yes you are right my frame is the other way up Wasnt thinking straight there
Note to myself :engage brain before fingers
Clemco
Clemco
430 posts
430 posts
30 Nov 2010 7:02pm



Fitted the seat and bolted on some wheels to test the spring. Only droped ablit 50-75 mm when I bonced on it. It should sit level once I put on the 400 x 8 wheels. I think I might flip the frame over. It will be easer to keep clean.
Test pilot 1
Test pilot 1
WA
1430 posts
WA, 1430 posts
30 Nov 2010 11:15pm
Hiko said...

Yes you are right my frame is the other way up Wasnt thinking straight there
Note to myself :engage brain before fingers


Hiko I think you are still correct. With the axle on the back of the ski there will be a twist imparted and cause a slight toe in/ toe out effect that is not dependant on the shape of the frame ends.
Clemco
Clemco
430 posts
430 posts
1 Dec 2010 7:45am
Test pilot 1 said...

Hiko said...

Yes you are right my frame is the other way up Wasnt thinking straight there
Note to myself :engage brain before fingers


Hiko I think you are still correct. With the axle on the back of the ski there will be a twist imparted and cause a slight toe in/ toe out effect that is not dependant on the shape of the frame ends.



Yes you guys could be right. That is what I hope to find out, so I can position the stub axle to counteract the effect. I find if you take things to extremes it is easier to see what is going on.
cisco
cisco
QLD
12365 posts
QLD, 12365 posts
1 Dec 2010 12:04pm
Clemco said...

How can it? as it is on the under side of the ski. I will have large washers on the nuts when it is finished.


Just wondering whether a plate over the two bolts either side would be better.

Admittedly a little more weight but it would certainly back up the strength of the skis.

Sandwich plateing the stub axles to the end of the skis seems a good idea to me as well.

Clemco
Clemco
430 posts
430 posts
2 Dec 2010 7:20pm
The other end of the ski could make a good second leaf to spread the load.
I might need that.

Clemco
Clemco
430 posts
430 posts
19 Jan 2011 3:07pm



Finally got some wheels for the little critter. Went with the NZ made ones just to be loyal. Also was lucky enough to find some 400x8 Cheng Shin smoothys which fitted perfectly. Scarce as hens teeth I am told. They will be good on the beach but not sure how they will last on the salt. I am trying to fit it all into a nice airline package 25kg max so I can get over to WA later this year. So far all looking good. The wheels weighed 2.9kg each with bearings and spacers. Still a bit of welding to do on the mast post and fit the folding deck-chair type seat.
cisco
cisco
QLD
12365 posts
QLD, 12365 posts
20 Jan 2011 1:37am
That is looking like a really compact package there Clemco.

Keep in mind that it not necessary or recommended to have the tyres inflated during air freighting.

They could explode and you could be arrested.
landyacht
landyacht
WA
5921 posts
WA, 5921 posts
21 Jan 2011 8:36pm
silly suggestion, If you leave those awful smoothie things at home and just bring some rims then fit some ribbed tyres here at $17 aus tyre and tube. that would very likely get your weight down. . ( and give me a chance)
grlynch
grlynch
QLD
208 posts
QLD, 208 posts
28 Jan 2011 8:38pm
landyacht said...

silly suggestion, If you leave those awful smoothie things at home and just bring some rims then fit some ribbed tyres here at $17 aus tyre and tube. that would very likely get your weight down. . ( and give me a chance)


Hey paul, Just a quickie, Where are you guys getting tyres and tubes from? I'm just looking for the best deal?
Thanks
Nikrum
Nikrum
TAS
1972 posts
TAS, 1972 posts
28 Jan 2011 11:53pm
Yeah! And do they have a Web or email address.
Are they better than those $25 Chinese Crap?
Ron
cisco
cisco
QLD
12365 posts
QLD, 12365 posts
29 Jan 2011 9:14am
grlynch said...
Hey paul, Just a quickie, Where are you guys getting tyres and tubes from? I'm just looking for the best deal?
Thanks


One place it seems best not to get them is tyre retailers. They generally charge more for the tyres we use than car tyres.

A place where you might get a good deal is your local ride-on mower shop.

sn
sn
WA
2775 posts
sn sn
WA, 2775 posts
29 Jan 2011 7:29am
The last set of 8 x 4 ribbed tyres I bought came from Mullins wheels (as recommended by Paul)

I think they have distribution agencies in each state.

They were $16.00 for each ribbed tyre and tube ($64.00 for 4 tyres and tubes) but might have changed price since then.

Just make sure the tubes are the correct size- 2 of the tubes that came with the tyres were 8" x 3" while the other 2 were 8" x 4"

Ring them first so you can take correct cash.
landyacht
landyacht
WA
5921 posts
WA, 5921 posts
30 Jan 2011 8:48pm
yep , Mullins Wheels. you dont want the road ribbed, just the 4ply light duty ribbed
Clemco
Clemco
430 posts
430 posts
18 Mar 2011 7:08pm


Got some wheels on at last.

I know, I have probably made it over complicated. It is to give me lots of adjustments to fine tune, then I make the simple one.

Testing the flex.
Clemco
Clemco
430 posts
430 posts
25 Mar 2011 11:39am


To set up the wheel alignment I strapped straight edges to the rear wheels set horizontal, then bounced on the frame to see if it would toe in or out. And guess what, TP1 you were right, it did toe in, but only slightly. I guess I will have to get it finished and test it on the beach to see how that effects performance. Then make the changes to correct it if needed.
Test pilot 1
Test pilot 1
WA
1430 posts
WA, 1430 posts
25 Mar 2011 4:57pm
I'm right!


I'm right!


Again, again



I'm right!
[}:)]
Clemco
Clemco
430 posts
430 posts
25 Mar 2011 7:05pm
Well partly TP1....... I also tried it with the stubs in front of the end of the ski axles, ( as in the last photo) and it still toed in but only half as much. 10mm each side. I guess I'll just have to sail it before I can make any sense of that.
Clemco
Clemco
430 posts
430 posts
14 Apr 2011 7:43am


Mast post welded off. Foot pedal and steering linkages attached. Now just have figure out how to attach the sling seat from the last model. Good wind forecast for Saturday so I am aiming to finish it off by Friday night!
landyacht
landyacht
WA
5921 posts
WA, 5921 posts
14 Apr 2011 9:04pm
Clemco said...


. Now just have figure out how to attach the sling seat from the last model.

I would be having the same problem , If I was working on a new yacht , which im not, so its not a problem[}:)]

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