Hi everyone
I am very impressed with the info on building the Lake Lefroy Mini Yacht. The biggest problem I have here in Yeppoon is finding the steel tube that is suitable for the frame. I am also designing a recumbent trike with all the whistles and bells and again, I have the problem of finding some suitable tubing. I saw a recumbent trike on the highway and instantly noticed (from 100 meters)``, that it was different. This trike had a square RHS frame as opposed to a round tublar frame. After lots of digging and searching, I found that square tube having the same perimeter and thickness as round tube, is 33% stiffer than the round tube. This is because there are two vertical webs to take the bending loads applied to the frame. The two horizontal surfaces (the top and bottom of the square RHS) are better equiped to take the forces that apply to these surfaces. This means that a much stiffer frame can be built from RHS and if extra stiffening is required for the bending stresses, then the usual round rod can be fitted and triangulated underneath the frame as needed. This will be the method that I will use to build my L/Sailer and it looks like it will be the Lake Lefroy Mini Yacht. Many thanks for the info shared on the post for this L/S.

Kody

Nice piece of research Kody. The square tube is ideal for the BACK AXLE assembly. as the loads are all vertical or horizontal, the main beam has all torsional loads ie twist. the square tubes fail miserably in this respect, hence the round tube . In a yacht this small it should be possible to use a glvanized steel pipe on the main beam. When we get to the building pat of the mini construction I intend to build 1 yacht in drill tube and another in Gal pipe and then compare the 2 yachtwhen sailing.
If the experiment works ( I think it will) then it opens a new age in Land yacht construction . Really cheap , fast yachts . With all the running off to Argentina, and now Gillies I havent been able to do much on the site , but after Easter I should be able to continue what I started, . The thread grows by me actually making the bit and THEN taking the photo and doing the talk .
One of the problems encountered was that the in last building session of 5 chassis the other participants were supposed to draw up CAD plans as part of the deal , but instead they all dissapeared with their yachts , never to be seen again.
Lesson learnt. I still have their sails

Hi guys
this is my first attempt to upload a CAD drawing. I dont think it will reproduce the way I am hoping. Can anyone help me to set a CAD drawing here that retains the original detail? The drawing is a preliminary drawing of the hub I will build.

Kody

Im interested Do you see yourself being able to make up lightweight hub sets to sell?

Hi guys
It's wonderful to get so much feed back from everyone, it is most appreciated. I initialy chose tapered roller bearings as they are cheap and can take enormous side loads. standard deep groove bearings dont handle heavy side (axial) loads for very long. They certainly are cheap and can be replaced easily (?) in the offending hub using a heavy knockometer.
The bearings I am using in the recumbent trike I am building are called "Angular Contact Bearings". These are a ball type of bearing designed to withstand huge axial loads as well as radial loads. I would concider this style of bearing to be the ultimate bearing of choice for a competition L/S able to run at speeds greater than 140kph. These bearings would need to be set in a special hub and lubricated with automatic transmission oil. Grease is not a suitable lubricant for high speeds. Tapered roller bearings lubricated with grease will never compete with a deep groove bearing if you're looking for high speed. I have no idea how much horse power is extracted from the wind with a sail but I assume it would not be very high. With a limited amount of power, the enemy is drag and grease in a bearing equates to high drag.
Now for the bad news, the cost of Angular Contact bearings would be around $70.00 for each wheel. I can make a lightweight housing using machine grade aluminium (am using it for my trike hubs) but the difficulty is mounting the hub within a steel wheel. I will have to check out the availabe steel wheels to then produce a method of attachment.
The machining grade aluminium is very strong but it does not bend neither can it be hammered to shape it. I dont know about its weldability but any welding would destroy the precision of the hub and its physical properties. I could produce a single hub for trying out (Lachlan) but I need to know all the info about your wheel/s and axles. An educated guess for material alone for the hub would be around $35.00. This might be more, depends on the method of attachment to the wheel.

Kody

Unless you build a yacht weighing 500kg I dont think youll need much more than a ball bearing. They roll better and you want to roll . the fastest sailing direction will be a broad reach, ie not a lot of side load.
Vindicator has the inside seals removed and sits in a shallow coating of light machine oil. 15" rim with Michelin X tyres will spin for about .5 mins after winding up by hand . Same bearings as used in 1993 Pacrims

landyacht said...

Unless you build a yacht weighing 500kg I dont think youll need much more than a ball bearing. They roll better and you want to roll . the fastest sailing direction will be a broad reach, ie not a lot of side load.
Vindicator has the inside seals removed and sits in a shallow coating of light machine oil. 15" rim with Michelin X tyres will spin for about .5 mins after winding up by hand . Same bearings as used in 1993 Pacrims

OK - Wheel spinning competition!! Only spinning them by hand I got 1 min 58 sec on my best wheel

I have the 8" metal wheels with $13 deep groove bearings (EE9-2RS-JAP) with the grease replaced with sewing machine oil. Inside seals have been removed and a metal sleeve welded in to hold them in place.

Can the experts provide some details on how to balance a wheel. Mine are in desperate need of this. After it stopped spinning it span backwards for another half a turn.

Yeah I think I might upgrade. Are the Fallshaws a reasonably consistant quality?

hills said...

OK - Wheel spinning competition!! Only spinning them by hand I got 1 min 58 sec on my best wheel

I have the 8" metal wheels with $13 deep groove bearings (EE9-2RS-JAP) with the grease replaced with sewing machine oil. Inside seals have been removed and a metal sleeve welded in to hold them in place.

Can the experts provide some details on how to balance a wheel. Mine are in desperate need of this. After it stopped spinning it span backwards for another half a turn.

I'm gald I did that rather silly test the other day as I have now balanced the wheel by Kody's instructions and it spun for 2 minutes 59 seconds today.

landyacht said...

Are the chinese gear really thin steel? if not then tell me more. the fallshaw wheels are really quite good.

Without a micrometre I'd say they're the same guage steel both in the dish and the tube that goes through the middle of the wheel. They don't look as high quality as the Fallshaw but they seem to spin truer as I said before. Mullins wheels sell them as part number 660-205 "INDUST WHL 8x2.5 Ball welded" BTW I just found a sticker stating they're made in Taiwan not China

Maybe I just got a bad Fallshaw. I'll get some bearings and a tyre and see if it looks any better complete.