After much thought and consideration I have decided to give Frog's Leg's 1 (FL1) to my dad to compete and started building Frog's Leg's 2 (FL2).

FL2 is being designed and tested alongside FL1.

An interesting habit of FL1 was a slight sway (not uncontrollable) when approaching higher speeds 55kph+

I believe this high speed sway may be caused because due to one or a combination of the following factors:
-Too little weight on the front wheel.
-CoG too high
-Wheelbase too short
-Chassis/Axles to flexible (possibly because I am only using 30x30x2mm RHS)
-Pilot too heavy.

I suspect the wheelbase is too short.
Current measurements are:
-Width: 1660mm
-Length: 1570mm

Compare this to a LLM
-Width:1510mm
-Length: 1640mm

To make FL2 I will keep the chassis materials the same and I will only change the axle sweep from 20 Degrees to 30 Degrees. By doing this it should reduce the width by 130mm and increase the length by 130mm.

This will also affect the balance point by moving it back and hopefully allowing more weight on the front wheel.

FL1 Specs
Mast Rake: 12 Degrees
Steering Angle: 50 Degrees
Front Wheel Weight: 10kg
Mast Tube: 400mm
Spine: Diamond Drill Rod 1000mm
Axle Sweep: 20 Degree
Axle Length: 800mm
Axle Material: 30x30x2mm Gal. RHS

Hopefully dad will spend some time on FL1 because at the moment looks like one of these


When I'm finished FL2 would look like one of these.


Ben.

Great to get into the good books with your Dad !!!!!
Will he still be around for Lefroy at the end of September meet? I hope so.

My last 2 mini's are now 1705mm long, axle centre to axle centre.
Width is 1571mm to the outside of both the rims at the axle height. The 1 degree of rear wheel camber, would add a bit more to the overall width.

The rear 30mm x30mm x 2mm RHS (which is only 500mm long on mine and sticks out of the chassis by 400mm, plus the 20mm shafting.) was flexing too much with larger sails, so that's why I added a 280mm long, 25mm x 25mm x 1.6mm internal stiffener. It starts 60mm from the inboard end of the axle.

It made a huge difference.
I noticed this, as my 3 degree camber axle didn't have a stiffener and when I had one of each (3 degrees and 1 degree) fitted for testing at the same time, it really showed up how much flex there was.
It was the forward to rear flex that was the problem.

Following Lyndon's yacht with a timber axle, it really stores the energy well and cant flex fore-aft, so is a great design.

I know for certain you are much lighter that myself, but at around 700mm, it is a fair bit longer lever on your "Frogs legs".

FL2 Building Schedule
1. Back End
2. Mast and Spine
3. Front end
4. Steering
5. Seat
6. Rigging
7. Sailmaking

Complete a few tasks over the last couple of days. Up to the front end tomorrow.

Quick measurement of the width is 1630mm. I will need to trim the rear axles as the 6degree cambered axle stubs add at least 80mm to the overall width.

Here are some pictures of progress so far.


















Hopefully working on the front end tomorrow.

Ben.

Great job there Ben, comp is getting stronger

Did some work on my front end today.

I spoke to Dad today and he said he may be building an 'all timber' yacht so I will have to set up FL1 for my mum.





Hopefully finish off the front end tomorrow and start work on the steering system.

Ben.

So this "all timber yacht", is it just going to be a "partial timber yacht" or really an "all timber yacht",wood wheels, wood axles, plywood sail, wooden lever downhaul system, you know, an "all timber yacht" because I reckon an "all timber yacht" would be real cool

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Test pilot 1 said..
So this "all timber yacht", is it just going to be a "partial timber yacht" or really an "all timber yacht",wood wheels, wood axles, plywood sail, wooden lever downhaul system, you know, an "all timber yacht" because I reckon an "all timber yacht" would be real cool

Cool if your a termite.

Hey Ben, buy one of these off fleabay.
You will wonder how the hell you did without it.

I've had mine for 3 years now and everyone who has borrowed it, now has there own. At least 6 so far.

The numbers invert as they pass 90 degrees and more importantly it can be calibrated by tapping the button to reset zero. So if your steering is say 25 degrees tap calibrate and then it will read the angle on your next component. It reads accurately to 1/10 of a degree and even gives you the up and down bar graph at the sides to show you which way to move to get ZERO.

Also it's really good as you can chock the rear frame to anywhere and calibrate it to ZERO and then just set your mast step to 90 degrees and tack it with the welder, done. Axle camber is a breeze to. The magnets are really strong!!!
Because you can calibrate it, most components can now be done on the bench to save my old back.



http://www.ebay.com.au/itm/Digital-Bevel-Box-Inclinometer-Angle-Gauge-Meter-Protractor-360-Magnets-Base-/271005671796?pt=LH_DefaultDomain_15&hash=item3f19326174

I'm sold chook. I will have to buy one and add to my toolbox. Looks a bit high tech. All previous yachts were built with my low tech primary school protractor. Very third-world fabrication technology.

Ben.

Sometimes "Bumblings" have them too, but wan't their pound of flesh.
Atoms might be worth a go though. They do take a while in the post from over seas.


The apps on the smart phones are not too bad either. google "spirit level" and there are heaps. Try and get a digital with tenths of a degree and keep the sparks away from your screen. I didn't while checking mine against my meter.

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Chook2 said..
Sometimes "Bumblings" have them too, but wan't their pound of flesh.
Atoms might be worth a go though. They do take a while in the post from over seas.

I'll check out ATOM. I love ATOM its my favourite shop. I spend more time (and money ) in there than the supermarket.

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BenBoulder said..
All previous yachts were built with my low tech primary school protractor. Very third-world fabrication technology.

Ben.

somehow, my sons school protractors managed to get lots of bits of welding slag melted into them.

took a bit of explaining to his maths teacher at the parent teacher interview...


stephen

Nice build!
It's great to see the different ways to attach the axles of these crafts.

Regarding the sway at speed, reminds me of the well worn steering/suspension parts of a high mileage old car I had. Could it be attributed to "dead zone" freeplay in the front steering? Would it go away if you charted a sailing path with a slight curve to keep one side always preloaded? Just a thought...

Chook sold me! I'll have to add one of those digital protractors to my toolbox too.

Thanks JunkSmith,

I will investigate the steering components for free play and see if it helps FL1 high speed sway.

It was weird feeling when FL1 started to sway. I have only experienced it once before on Barrys' y-frame mini last year at Lake Lefroy. Only happened when approaching higher speeds.





Ben.

Completed front end today. Steering will have to wait until next break.

Rear axles need trimming 50mm each.









I'm a long way off finishing but I should be well on track next time.

Ben.

Love the dunny with central heating, even Bazza should be impressed.

What are the square bushes you use in the steering head pivot Ben?

Bushing is black irrigation pipe that was in the garden fits the 12mm bolt. There are 3 layers. Central core then shimmed with 2 other pieces split the fit tight in the 25x25x2.5 RHS.

High tech? No. Its what I found and it seemed to work on FL1.

Until I find a better solution the black poly will do.

I wonder if the poly is walking around and this is causing the movement. Although you mentioned Barry's yacht did it as well.

Wonder if you drilled the 1/2" holes first, then cut up a nylon cutting board and fabbed up the bushes by stacking them up, it would be less play???

Even bonding them into the RHS with araldite to take up any imperfections of the edges.

I'm loving the pictorial sequence of your construction. Keep them coming Ben.

Got a small fleet together for a sail today. less than impressive winds so got an opportunity for a few happy snaps.

Put my class 5 sail on Frog's Leg's one and tested the skinny front end from Frog's Leg's 2.

Both performed pretty good but will need to spend some time tweaking the sail adjustments.

Building has been a bit slack as trying to organise the regatta next month, learning to cut and sew sails, promoting landsailing and selling blokarts.







Ben.

Nice little fleet there guys, is that the claypan

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aus230 said..
Nice little fleet there guys, is that the claypan

Yes Vic, that was the claypan. Dads' black poly and fabric tape sail perform surprisingly well. It had plenty of bottom end grunt. When the rest were waiting for wind he was rolling. not bad for a $7 sail.

I can't beat 7 bucks ( can anyone???), but how about 7sqm? Size matters, when wind is low...




If 'm getting to weld some day, i'd like to do something "Legs-like"...
Thanks for all the pictures!!!

Don't worry JoeHanson I will post the plans for Frog's Leg's one and two so you can have a go building one.

Yes. Lots of Pictures. A picture says a thousand words.

Ben.

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BenBoulder said..
Bushing is black irrigation pipe that was in the garden fits the 12mm bolt. There are 3 layers. Central core then shimmed with 2 other pieces split the fit tight in the 25x25x2.5 RHS.

High tech? No. Its what I found and it seemed to work on FL1.

Until I find a better solution the black poly will do.

Select to expand quote

Chook2 said..
I wonder if the poly is walking around and this is causing the movement. Although you mentioned Barry's yacht did it as well.

Wonder if you drilled the 1/2" holes first, then cut up a nylon cutting board and fabbed up the bushes by stacking them up, it would be less play???

Even bonding them into the RHS with araldite to take up any imperfections of the edges.

I'm loving the pictorial sequence of your construction. Keep them coming Ben.

Hi guys new to forum, about steering head bushes, I have used a nylon cutting board to make bushes. Haven't tried them yet but they feel good when assembled

Pulled FL1 out of the yard and started inspecting measurements and for wear and tear.

Fits the 5.6m rule but maxed out.

Made new steering bushes for the bigwheel fron end.

Found a bent axle. The 30x30x2mm axle bent where it goes into the axle receiver. I don't know when it bent as I didn't lift wheels and slam the yacht down. The material is probably over spanned. I will have make them shorter or add internal 25x25x2mm rhs stiffners.

Just hold the axle in the vice between two bits of wood and lever it straight, with another bit of tube that slips over it. It is surprisingly easy to do.

Then just add your stiffener. I centre punch the stiffener, once all four sides each end, from the inside out 5mm in from the ends (while holding over some wood to make four EXTERNAL dimples each end). This makes 8 dimples on the outside of your stiffener to locate it. Give it a real crack to get some nice deformation happening.

Drive the stiffeners in with another bit of 25x 25 x1.6 to where you want it. The centre pops hold it in position without having to weld it.