To introduce a moment of whimsy into this dour and serious conversation, my ‘Phinn-ichthy’ masses out at a feather-weight 2.13 KILOgrams, when taken down to a reasonable waterline. This is bare hull, no rig, no electrics.
It may, and I stress ‘may’, give some data upon the effectiveness of an ultra large rig and a hull that does not bounce over the waves.
Rod,
Thats a lot of boat, and all the weight inside the hull!
Just about meets Firstfooty’s weed free “schooner” requirement, too. How is she going and what type of rig?
andrew
I can see that I shall have to actually do some work on my Phinn over Xmas while your water is frozen if I am to have the first Phinn-type footy on the water.
Interesting that your technique for sealing the hull joint is essentially the same as mine. I used a slurry of microballoons and Burgess wood sealer. The latter, if you don’t know it, is a water based resin. Paint it onto wood and it capilliaries into the fibres before the water dries out and the resin goes off. It increases the strength and toughness of balsa structures no end for negligible weight increase.
Mix it as a slurry with suitable fillers and it makes a very penetrating, very adhesive mix. It takes a while to go off of course but it reaches into all the little cracks in the seams. One day I shall attempt a hard chine design entirely glued up and painted with it.
Russell
For Historyman:
Some photos of current status, showing dimensions, profile and balance point. The CLR is about 1 inch behind amidships. Beam is 4 inches. I intend to have a rather large sail area on a tall carbon tube mast. The batteries will be down on top of the lead, while the electronics will be mounted in pink foam blocks about an inch below deck level, held in place by their own pressure on the sides.
If she needs to be smaller, I can cut out the deck and replace with narrower, and retrieve all my lead shot as it is merely jammed in place with more pink foam.
Proof in the pudding! Oh, for nice soft water!
Rod
Thanks for the piccies. Yours is even more of a goliath than the original Phin. I discover I have been inadvertently spelling it with two n’s, making it look as though it has an Irish connotation. Paint it green and call it Cathleen-na Houlihan?
Russell
Happy New Year, everyone,
especially builders of radical footys and historians
Good news, while talking with somebody about something technical I was reminded of the peristaltic principle, and realised that this has the potential to re-instate my elegant aft rudder on the ZBF.
It really needs a hydraulic drive to operate the rudder as both servo and rudder are 12 inches under water.
By the way have you all seen these?
http://www.firgelli.com/ - they would be seriously neat on the rig of a macrig?
How is the derby US1M footy progressing?
andrew
What idiot is building a radical historian now?
Happy New Year
Why does my head snap up at the mention of idiot?
At least a radical historian would know, not necessarily the way forward, but what happened previously on that track:)
If it fits in the box its a footy!
I was tempted to title this:
“Look on my works ye mighty and despair”
till I remembered what happened to the first person to utter them.
ZBF progresses to the point where she can be seen in all her glory, he said modestly.
The Buoyancy compensator exists in my head, but nowhe else at the moment - I will carve a small one to begin with - the BC is intended to merely touch the surface but resist heeling and nosediving - I am sure that there is a hydrofoil shape which can do this, but I can’t yet envisage it.
For photo reasons ZBF has stolen the rig off Lightfoot - I will make a very low aspect macRig for trials - probably one skewer high.
Control drives exist, too, in my mind, and I have selected the concentric tubes for them. Batteries have been rearranged to lie 2 +2 on the floor of the hull with the lead ballast - since I need space near the Vertical hull extension to connect linkages.
more as it hapens
andrew
Andrewh
I had assumed you were having us on, as the saying goes, but your design seems to be a possible.
I would assume you could use regular servos driving vertical shafts up the ‘stem’ to the surface. The ‘stem’ would need to have capacity only for the off-on switch wires, two shafts and the antenna. The steering and sail arms would be in the surface module, which would need only to provide floatation and anti-diving capability.
Ingenious! I had assumed only I was quite so nuts.
Just loads of ‘assumptions’!!!
Rod
Razor 08 CAN
I’m very nearly certain that it will flop (literally) because of a fundametal misunderstanding of how stability works - but it has a grain of logic running through it that says ‘or am I wrong?’
Keep us posted.
My own inclination is that it still needs the lateral resistance of a fin. If I were making it I would have the most fin on the bottom and almost no fin on the top.
I would let the buoyancy compensator rotate to find it’s own best position or give it perfect radial symmetry. (Turn it on a lathe)
And of course, I would put a rigid wing on it!
But that’s me.
This is a very interesting idea. It has me really wondering.
Edit: I understand Angus’ objection. The righting moment normally comes from weight hanging on a rigid arm below something floating on the surface. Here you have the weight but nothing for it to hang from.
I would also think in terms of a full length tab on the trailing edge of the fin (which you don’t have, or haven’t shown yet) that works in opposition to the rudder. Say 20 percent of rudder deflection but in the opposite direction. It could still be worked by one servo. Maybe the tab only has to be at the bottom of the fin.
This is radical enough to be difficult to imagine.
Pete
EVERYTHING hangs on the “very nearly” doesn’t it?
I am a great believer in many of the axioms of Robert Heinlein - one of which is:
“listen carefully to experts - they will tell you why it can’t be done
then do it”
ZBF as she now exists is sort of a conceptual mark lV. Originally the stability was to be provided by a trained cephalopod (called Darcy - I thought that classical traning in pirouettes would be useful, given my driving skills).
For trivial reasons she was suppplanted by the dirigible sail - hydrogen-filled and large enough to provide significant lift - which was to provide the roll stability - see sketch attached.
The lifting sail is still in the frame, but for reasons of “shooting the engineer and cutting metal” the Mklll dispensed with these stability aids, This is the craft I sketched previously and really required hydraulic rudder operation and a gryo to provide dynamic roll stability using differential rudder segments. There was to be a small, conical BC to mollify Archimedes.
All this purity (and radicalism) has been shelved in favour of the doable, but horrid buoyancy compensator and forward vertical hull extension or, as Rod puts it “stem”.
This WILL work - and I hope to drag the footy community (kicking and screaming, naturally) into the century of the Fruitbat.
Rod - thanks for the compliment, praps the radical strapline should be:
“Footy box may contain nuts”
I like the differential rudder, but I think you can’t control it properly with one servo. It still needs lateral resistance because the rear location of the rudder vs sail will cause it to want to run downwind no matter how you deflect the rudder.
Hmm…
I would have half the rudder above the hull and half below, with differential deflection and normal rudder control, and a large “shark fin” projecting up. A rudder needs something to work against. Sharks and atomic submarines both have fins projecting up that the control surfaces work against.
The sail on a modern submarine also causes it to bank on the turns, which is good considering how fast they go.
I am turning into quite a blabber mouth. I hope you don’t mind too much.
BTW. I think Heinlein was a genius. I grew up reading his stuff, and learning from it.
Pete
Pete
I didnt expect to control the differential rudder with a single servo - a gyro was going to do the roll control and mix with rudder control from the radio - we are only allowed two function channels from the r/c but can use owt else not forbidden.
Thanks for your thoughts - I will ponder them. I fear you may well be right about the lateral resistance, but don’t want you to be!
Gyros are great. I have a very light airplane with a video camera in it, and adding a gyro helped the video considerably.
I was thinking of a heading hold gyro to hold the course on a normal footy, but not having sailed on yet I don’t know if I would really need one.
In case you are not familiar with them there are two types, rate, which is inexpensive and just tries to compensate for gusts, and a more expensive type called a heading hold gyro, used mainly in helicopters. It tries to calculate how much of a turn is deliberate and how much is cause by various disturbances. It then tries to restore the heli to the heading that it “thinks” is what you have steered. If you don’t add yaw input at all a heading hold gyro will compensate for disturbances by returning to it’s initial heading. The rate type will fight changes but not return to a heading once disturbed.
I am about two hours late today, so I am off to work for my first lateness of the new year. I should just take the day off, but at least it will be a shorter than normal day.
Pete
If the underwater ‘HULL’ has zero buoyancy, then its ‘weight’ would be zero and the righting moment would also be zero. It would lie at any angle in the water unless the ‘bouyancy compensator’ actually has full bouyancy of its own and the ZBH has negative bouyancy. In effect, it would behave as an extremely light Footy with a very small weight of keel bulb, and would be very easily heeled. All the advantages of this ‘light weight’ would be lost, however, as the whole boat would still have mass to resist acceleration.
Or am I making an error here?
rod,
Thanks for your thoughts, which are likely to have much truth in them and they would carry the day in a pure discussion.
But some idiot has made one, and in the fullness of time we will see if there is any benefit in (even a part) of the concept
<<All the advantages of this ‘light weight’ would be lost, however, as the whole boat would still have mass to resist acceleration.>>
The mass is as you say still there, and will resist acceleration, true:)
The whole conceptual basis of this footy, however is
A) to eliminate the displacement wave-forming limitation on the footy (by eliminating the displacement element)
B) to stimulate off the wall thought/trials/boggle factor among the Phooty phreaks worldwide
Little matters 
like total lack of “stability” (in the conventional sense) and possible absence of side area giving the rudder no purchase as well as control of buoyancy must be considered as interesting, true but regrettable losses in the cause of purity.
The BC will regulate not only static buoyancy but is also intended to apply a dynamic righting moment to give a sorta stability by virtue of its shape.
Side area can be provided in the blink of an eye by sheathing the VHE (or stem) with something flat.
Maybe I will just increase Darcy’s training regime but
As a Scot was hoping to build ZBF for less than a squid
Sorry!
Andrewh
I have often contemplated the possibility if making a mast-keel unit, which would be free to pivot from side-to-side in a vertical plane, while leaving the hull in an optimal orientation for floating, movement through the water, and wave-penetration. The keel could be merely tubular with a ballast bulb (suitably faired) while the hydrodynamic forces to resist sideways movement was provided by a fin or fins attached to the hull. The fins would remain oriented vertically, as would the rudder.
This would not be compatible with your ZBF concept, except insofar as the ballast weight in the bulb could consist of electronics and batteries. Unfortunately, that would violate the definition “within the hull”.
Andrewh
Something like this.