Today started project 'Frog's Leg's' French inspired mini-promo.

Building conditions were extremely hot and humid. Reminds me when I lived in Bangkok. No not because I had beautiful women around my place today.

Inspiration came from Seagulls' mini-promo and Airtracks' Nano skoot. Seagull hasn't said yes or no to plan's but Airtrack said a definite NO they won't sell me plans. As if I am I going to buy a yacht made in France and pay for postage to Australia. So I decided to have a go myself just by looking and pictures and using my apprentice yacht building skills.






Day 1 build:

-Made rear axle 600x35x35x2Wall cut @ 70degree to give 20 degree axle sweep. Same as Promo Class 5. it took about 50minutes to complete and weighs 1kg.




-Chassis Spine selection: Had a range of LTK60 Inner tubes and BQ core tube. Weighed these to find out which had the least mass. I chose the used BQ core tube as it had the least mass 2.22kg/m and cut to 1300mm.





-To support the rear axles I cut some 50x20x2 and tack welded into place.



Before the welding comments come this was after 6 beers and severe dehydration but nothing the grinder can't fix.

I am jealous of you builders that have shed to complete your builds. It usually takes 40min to set up/pack up tools .

Here are some pictures of Benny's Yacht Facility.









Ben Boulder.

Nice free plan wall-less shed

yes wayne, to let the heat out and the thieves in.

Happy New Year !....... Ben....wel-done

Nice plan Ben.
I would build in a bit more ground clearance though. Those axials flex a bit and the tires loose a bit of height when you hop in. I would add another 50mm there.

Build Day 2:

Today was a wash out. I completed my FLRA and deemed to unsafe to operate power tools under these conditions.







Thanks Clem. I will raise the ground clearance to 100mm and check it once it's rigged and I'm in it or I feel like I'm operating a scraper.




Today was my academic day where I started planning the front end/steering for the yacht.

There are several design variations for the mini promo.








I have decided to make the steering similar to the one with the silver seat but was unsure how this yacht would steer as I have only had experience sailing a LLM with layover/roll steering so I decided to compare the trail of both.






TRAIL=[Tire Radius x Tangent (Rake Angle)] - [Offset/Cosine(rake angle)]

Layover Roll Steering

Trail = [200 x (Tan60)] - [150/(Cos60)]
Trail = 346.41-300
Trail = 46.41mm

Silver Seat Cable Steering

Trail= [200x (tan30)] - [70/(cos30)]
Trail= 115.47-80.82
Trail= 34.65mm

My figures could be incorrect because I had drawn over printed pictures and measured.

I hope the rain stops only got 5 days left until I'm back to work.

Ben.

Bonjour and happy new year.
Sorry to hear that the French did not gave any plans...
May be this can help?

Select to expand quote

frogy said..

Bonjour and happy new year.
Sorry to hear that the French did not gave any plans...
May be this can help?

I wonder if my daughter the costume designer would be able to work with this diagram
I shouldnt worry about the plan thing. seagull do put up plans like the quebec when they become a historical thing.
so many images of minis on the web now . most of what Ive seen seems to be adaptations of present and past designs from other yachts.
I suggested 150mm clearance . in case walyungup has got rougher

What is the theory of the trail on the steering diagram?

I am interested as well as my understanding is that due to the side thrust land yacht steering
Should be neutral as to lead and trail

I'm just going of my experience of motor tricycles.

Too little trail=no feedback but easier to steer but poor high speed stability (Like a Moto GP Sports Bike)

Too much trail= tendency for the wheel to overcorrect itself all the time and difficult to corner. (Like a drag bike)

So what is the perfect trail for my Land yacht? It depends on a number of factors:
-weight on front tire
-tire width
-rake angle

e.g. On motorcycle trikes

100mm or more trail= good high speed stability but heavier steering and low speed steering wobble.

>76mm =very light steering but poor high speed handling.

At the moment this is still pretty new to me. I guess when I am up to making the front end I will test it. If it doesn't work I'll get out the grinder and the welder and try again. There is no magic number just what I like the feel of.

Ben.

You don't want any trail on a landyacht Ben. On a wheel driven vehicle the driving force is in the same line as the wheels. The driving force on a landyacht is the sail which has a lot of side force acting on the wheels.
Set the pivot pointing to the center of the patch of tyre touching the ground.
The angle of pivot is not that important. More vertical = less lay over. Less vertical = more lay over. 45 degrees would be a good compromise.

Thanks Clem, I really have NFI

This is only my 2nd year as an apprentice land yacht designer, builder and pilot.

Today finished welding rear axle supports, started designing and cutting rear axles current design is to make rear axles out of 30x30x2 x800 gal. This should give a width around 1800mm.

Decided to go wider rather than longer.

I borrowed the 5.6m rope to get me thinking.

Off to Class 5 building @ 10:00am today.


Ben.

Be prepared for a long Apprenticeship Ben, none of the 4 or 5 year terms are offered in Landyacht design or builds. I suggest closing off the end of the main circular spine where it branches into the axle stubs. The open pipe is subject to a lot of crushing at that point and salty dirt would love living in there. Hava good year....wok

plan for the front end from popeyethewelder.com the kite buggy man.



Ben.

Select to expand quote

BenBoulder said..

plan for the front end from popeyethewelder.com the kite buggy man.



Ben.

If you put a mast step behind this KITE BUGGY front end you will spend your days fighting it as it will be trying bear off? the wind all the time.
you want that pin angle on the contact point

Finally got a chance to do some building today.

Today's job list


Made some rear axle hangers with 10mm plate. Use 20mm drill bit and cheapie power drill. You know your drill is working hard when you need to wear two pairs of gloves to hang onto it.










Tested the mini with the official LLLSC 5.6m rope it fits to the maximum limit. I plan to reduce the rear wheel track as it is current 1800mm and doesn't fit comfortably in the back of my ute. The reduced track should give me more room to play with the front end.







The front end is giving me a headache. I am tossing up running the fallshaw(big foot) front end or my skinny 16" BMX wheel.
Here is a picture with the BMX wheel. The geometry looks wrong I must have made a bad drawing or calculation somewhere.
I have only tack welded the swan neck onto the mast tube as I pre-empted possible error on my part.
I think I might do what Vic (AUS230) suggested early by making my seat, rigging my yacht and weighing the front end.




With out plans and cutting list land yacht building takes a lot of time when your only available resource is pictures.







Once you get it right draw it. I probably could have build a couple of LLM in the time it's taken me to build one of these 'Super Minis'.


Ben.

Hi Ben, I've been away for 3 weeks without computer access. (Kite buggying in Yeppoon QLD)

On my LLMinis I have 10mm of trail for hard salt at Lake Lefroy, 40mm of trail for the softer gypsum, on Pink Lake, and Greg has 80mm of trail for the soft beaches here. The 80mm is because the wheel is sinking in and running uphill all the time, which reduces the true trail measurement. These measurements are with Fallshaw wheels.

These amounts give us just a slight touch of into wind on a broad reach, with our feet off the steering pedals.

Don't worry, I too have gone through a lot of cerial packets drawing out the geometry for both kite buggys and yachts to get them to behave. The mast rake and sail size alters all the parameters as well to a certain extent.
Mine are set up for larger sails as I'm a fat prick!!!!

After several weeks in hibernation project "Frogs Leg's" is back on track.

Redesigned front end that is similar to Seagull Mini Promo and Airtrack Nano Skoot.

New foot steering arrangment.

"Goolies Basher" removed. However may come back.

Started making some templates for the seat.

Current chassis weight is about 30kg with 10kg under the front wheel.

Still heaps of work to go but heaps of fun.

Ben.

This is very impressive Ben
Total respect

Agree, great job. Steering looks correct. Glad you got rid of that "nut cruncher". It looked more like a harpoon to me.
Foot peddle pivot bolt could be in a short tube welded to front of peddle, (bit like you have done the front fork to the piviot) to stop it sagging to one side. Nice welding!

NICE WORK!!!!

Looking great Ben.

Lots of good ideas there.

On the front wheel I make the horizontal piece across the steering pivot 6mm longer than needed (on the side that welds to the arm going down to the front axle).

This then angles it in slightly, to pick up the axle and gives the tyre a bit more side wall clearance in our muddy conditions.

Same thought as Clemco. Welding is improving out of sight. Awesome mate.

Excellent work Ben. Comp is heating up I think

Started mocking up a seat for my yacht. At the moment the seat is only a prototype just so I can test how my yacht sails.

If it works I will pretty it up later.

Seat made from 150x17mm fence palings and cheapish 7mm plywood screwed together with plaster board screws.

Seat is only tied on with rope at the moment. Once I am happy with the final design I will work on the aesthetics, permanent mounting and making from better material (marine ply, stainless steel screws etc.).

Timber is more forgiving than fibreglass and steel. You can cut holes, screw it, nail it or add more pieces. (e.g. I wanted to extend my head rest.)

Well I am back to work this week so 'Frog's Leg's' will have to wait another 7 days.

Ben.

excellent work there Ben. I also noticed the improved welding
glad to see you are keeping the game alive whilst im on sabatical.
i just need to keep drawing on my white board then check on seabreeze a week later to see how the idea is getting along

you do realize that a mini seat can go in front of the mast . that rule only applies to class 5

Looking good Ben
Paul are you trying to confuse me, does that word mean what I think it is.


Like your job but are exhausted, feeling like you're going nowhere, stuck in a routine, and need to re-energize? You may need a sabbatical

Get back building that will fix things

Today's progress hopped along slowly.

Seat has changed to have chassis inside. This should clean up airflow once I make my final seat. Finalising a nose design is still giving me headache.

Made new boom 1850mm from old RDM windsurfer tip. I had a few spare tips and some alum, I found this piece had the least flex plus it weighs next to nothing.

Finished rigging the centre sheeting. Used new rachet block and old blocks from a Hobie 14.

Seat belt from a Mercedes was also added.

I still have lots of work to go until finished but hopefully will be able to go for a test sail soon to test how it performs in its current set-up.

I will test its performance against my production blokart. If I can beat a production blokart good if not bad.

I am looking forward to my sailmaking short-course with Landyacht in 2 weeks.

Ben.

Frog's Legs Flies

Today assembled some training pilots to put Frog's Legs through its testing.

Winds were NW about 15-20knts with 25knt gusts. (face anemometer reading ).

Test venue was the claypan.

Training pilot Darrel aka 'The Joker' piloted the 'Bat Yacht' and posted a top speed of 45kph. Not bad for his first ever sail.

Training pilot Mick was in the Blokart with speeds in the low 50km/h.

I was piloting Frogs Leg's and was pushing low 60km/h speeds with a peak of 63km/h.

Frog's Legs perfomed better than I expected. Was rigged with a 490Mistral 1 piece Alum mast with 4.0mWild Winds Recut Sail.

The yacht displayed a few qwerks but after figuring out how to sail it 3 wheel drift at the bottom mark were pretty fun as well as 360's I call "Frog in a Blender"

Overall was really happy with how it performed in its current configuration. There are lots of little jobs to do until I am finished but they will have to wait for another 7 days.

Ben.

Green with envy that looks more like a near 540 mate.
looks like you are getting the edge of the cold front that moved through here this morning, bloody hammered down. Bit of a light show to go with it.
Seeing everyone else is moving mast steps forward with good results has inspired me to pull the mini out of the trailer and have a crack at keeping up with the Joneses.
Might wait for the end of the worlds though to see what the verdict is from some of the other builders and how their yachts went, if at all.

Moving the mast forward had definitely helped the yacht point better.

Ben.

Select to expand quote

said..
Looking good Ben
Paul are you trying to confuse me, does that word mean what I think it is.


Like your job but are exhausted, feeling like you're going nowhere, stuck in a routine, and need to re-energize? You may need a sabbatical

Get back building that will fix things

yes vic i decided thta id have a break from 2 designs each year. now if i have an idea i put it on the white board and let the boys see it . as a rest Ive just played with bikes. this years tally is a recumbent bike ,a tandem race/touring bike4 cycle speedway bikes(fell off one of them , 2 junior race bikes,a track bike( took 1 afternoon),
charlottes road bike is a real cracker, got it off gumtree with funds from selling landyachts.
my race bike is an old ally 9 speed banger, but last sunday in my first race back from the fall I won the handicap race by 5seconds!!!!!!!! kind of impressed myself