Shape should do. It’s not world beating, but it’s better than a lot. Try and slim the forward part down a bit.
If you have serious problems sourcing things, tell me what you need. I have a fair list of mail order sites in UK.
Angus
Perhaps rather than trying to slim down the forward part of the lead weight you could glue a small piece of wood, either balsa or some other wood and shape it to become the forward end of the bulb. Less hazard.
IanHB, onece more… this is becoming a fixation… what about waterproofing… is it just painted (with udercoating)? What do you think?
This solution sounds interesting, Graham would you be so kind and supply me with the necessary procedure so I can try it out… could you also quote some product names to be used… i.e. what’s this banana oil, do you get it from specialised outlets (DIY for example) what about tissue? Thanks a lot
nic
Lifted from instructions for one of my aircraft kits… and altered slightly to suit…
"For those new to tissue covering…
The fuselage (hull) is first given two coats of cellulose sanding sealer, sand gently between coats. Cellulose dope can be used but takes more coats to fill the grain and the greater shrinking power can curve the fuselage sides inwards, causing the aptly named ‘starved horse’ effect. Panels are cut from model covering tissue (light or medium weight) to fit the sides and bottom of the hull allowing an overlap of approx. 5mm (1/4"). These panels are then laid on the structure dry and more sanding sealer (slightly thinned) is brushed through the tissue to adhere it, sides first then bottom. The tissue will mould easily around gentle curves or can be snipped to go around compound curves. All will soon be dry and the overlaps and edges can be sanded flat with well worn fine sand paper. Apply two or three more coats of sanding sealer (sanding gently between each coat) to finish.
Either use coloured tissue or use plain white tissue and finish with a light coat of gloss enamel paint."
…
The tissue is sold in model shops for the purpose and has good wet strength… maybe ‘Modelspan’ or better still ‘Japanese tissue’. ‘Banana oil’ is a nonshrinking cellulose dope and is called that if they have it. Humbrol or Sig make cellulose dope and sanding sealer, or you may find Butyrate Dope and Sanding Sealer which is almost as good.
Apart from the sanding sealer these are model products, rarely found in a DIY store so you may have to go a different route. I have noticed that my balsa stem posts seal just as quickly as the ply panels (in my kits) using [FONT=Arial]‘Minwax Helmsman™ Spar Urethane’ brush on varnish… so if you can put up with not such a hard surface (as the dope/tissue will give) then that is a simpler route… 4 coats rubbed down between each one should work so long as your balsa is of a fairly hard (or medium) grade. Avoid buying soft or light balsa for this purpose.
Graham
[/FONT]
nic… I have started work on a new prototype boat for '07 called ‘Banshee’. I will be using the tissue/dope over balsa method to gain minimum weight and also to prove to myself whether dope can be used in conjunction with my foam core method… is the balsa enough protection for the foam!
So if all goes well I will be able to post some photos to give you an idea of it in action.
Further though… one way to avoid curved panels due to dope shrinkage is to coat both sides of each chine with dope at the same time.
Graham
Graham, Thanks for the detailed procedure for the application of the cellulose dope and tissue. I think it should be OK for the kids and should be able to handle it. As I argued earlier, saftey is a bit of an issue in this project. I am off to the Model Shop (which is one of the major model material outlet here in Malta) this afternoon to ‘hunt’ for the materials… hope to be successful so that I will start the procedure on the zerOne and see hw it goes.
Meanwhile, as Angus suggested, I am working on setting up a Blog with all necessary information about the project and hopefully it will be featured in the news section of the Footy Website!
On a simlar note, I have recieved a very interesting e-mail form an Italian teacher who must have read one of my posts. Salvatore informed me that he has been doing a similar project with his students for the past four years, and that he organises regattas quite often. I am still awaiting his reply to see which class of model boats they race. This is a great way to co-operate and increase awareness of this wonderful, some call it hobby, but I prefer to call is passion!!
nic
Cellulose Dope and tissue available!! will start waterproofing as soon as manage to go to the workshop… this week was hectic but will try to do something this weekend… (I am tuning and setting up the IOM for the nationals next month - but can’t get my mind off the project… have also designed the club logo!!
regards to all!!
Remember the warning about straight dope maybe shrinking the balsa too hard and causing the ‘starved horse’ syndrome. I remember an old free flighters remedy of adding glycerine to dope to stop the shrink action… I will try and find a source for that info.
You could thin the dope a good deal 50/50 with cellulose thinner (lacquer thinner in the uSA). That will help the dope to penetrate and may reduce some shrinkage on the initial coats.
Graham
Graham, thanks for the info… I came across this cellulose thinner too. I think that the best bet is to try it out on some access balsa i have… take some photos and upload them for your review!
regards
nic
During my ONLY free lesson today 
I started checking the Technology Education skills list. My main argument in the application form will be that building a Footy Class yacht will provide the opportunity to address most if not all skills as set by the education department.
IN OTHER WORDS: the more they match… the more the chance to get funding!!
These are the skills as set by our education Department:
[ul]
[li]Use mechanical components and construction kits.[/ul][INDENT]Servos application meet such demand.[/li]The kids will be supplied with footy kit.
[/INDENT][ul]
[li]Use secondary sources to help in their designing especially information technology.[/ul][INDENT]Students will be encouraged to use this forum or one especially designed for them to increase theor knoweldge and for trouble shooting.[/li][/INDENT][ul]
[li]Consider use and purpose when generating designs for their project.[/ul][INDENT]Study the anatomy of aa model boat, how sailing and sails work… obviously this will be done in a very ‘basic’ levels.[/li][/INDENT][ul]
[li]Develop clear ideas of what has to be done.[/ul][INDENT]The modelling of the yacht will be done as a group and every students will be asked to follow precise steps.[/li][/INDENT][ul]
[li]Plan how to proceed to make a product.[/ul][INDENT]Logistics of how to build the yacht will be discussed and an action plan devised by all the particpants.[/li][/INDENT][ul]
[li]Know that different materials have different properties and relate this to the way they may be used.[/ul][INDENT]Material Review mainly: balsa, carbon fibre, marine plywood. s/s rods, drafting paper, sheeting chord etc[/li][/INDENT][ul]
[li]Know that materials can be combined and mixed to create more useful properties.[/ul][INDENT]Cellulose Dope, cellulose thinner and tissue[/li][/INDENT][ul]
[li]Recognise that simple mechanisms can be used to produce different types of movement and structures.[/ul][INDENT]Servo geometry, sails movement and rudder control[/li]
[/INDENT]These are just my first thoughts… but I think that it should work out!
Any Comments?
At the risk of excommunication on my first posting on a r/c site, I would abandon the radio gear and build free sailing Footys instead.
Free sailing boats are cheaper easier and quicker to build. Its faster as well, mine are 200 gms against 600gms for my r/c boat, yet they can carry the same sail area.
Failing that, I would use a simple design which is easily built, to get everyone sailing with the minimum of hassle. At a later date you can upgrade the ballast bulb, rig, rudder etc and increase the performance.
For the hull, I would avoid Balsa wood as it takes a lot of finishing. I use 2mm Liteply or 0.8mm birch ply, depending on how much bending I need to do. Prime with Burgess Woodsealer, a water based resin and acrylic varnishes. Safer and quick drying.
I have not yet used Plasticard but as it needs no painting, it should be the best choice.
I use ‘gripaway fishing sinkers as ballast, not ideal but I have seen worse things on keels. You can fair it with ply discs on a nail, knocked in to nose, sand and apply filler. Fair the wire tail in rather than cutting it off.
For a lead flashing bulb see the free ’Wee Nip’ plans www.mmi.traplethouse.com
You can scale this bulb down in length and diameter to suit, but you can’t scale the thickness of the lead flashing, so a certain amount of fudging is required.
For r/c I use a single sail with a luff pocket. This is easy to make in polyester drawing film, stuck together with tape.
I do like simplicity for courses, our most basic course was for a group of six year old scouts. who built a 300mm foam boat and sailed in a two hour session, cost was 80 pence per boat.
I have sent the longer version by e-mail, If anyone is thinking of a course you are welcome to the latest version.
nicmifsud:
Came across this reference on another forum and thought it might be of use to you in planning your project:
http://pldaniels.com/flying/balsa/fiberglassing-model-aircraft-with-water-based-polyurethane.html
–Doug
Thanks Doug,
this system would be ideal…but there is a big BUT the article is about flying machines!!! what happens should this system be used in water??? being water based!!!
OOPS! The manufacturer’s data sheet says usable on (people-size) boats “above the waterline”. Sorry!
–Doug
If you consider the time that a Footy is actually likely to spend in the water in any one session, this may not be a problem.
I spray paint mine anyway. That should be ample protection for the time these spend in the water.
I’m using water-based Polyurethane ( called “Polycrylic”) http://www.minwax.com/products/protective/polycrylic.cfm
to coat all my Footies. I put on a coat or two to seal the balsa inside & out. I have not noticed much warpage of the 2mm balse sheets. And then a tack coat, to which I put on some very light (0.5 oz.) glass cloth. Followed by 2 or three more light coats on theoutside, sanding between.
With the IOM nationals next Saturday, I am very tight for time but this is how zerOne is looking at the moment… will start working on the keel and rudder soon…
Thanks for your comments re paints and materials…
nic
Looks good!