Here are a couple of pix. It is held together with masking tape and some thin CA, which ran a bit here and there. I will probably use some strips of .7 oz glass to strengthen and seal the seams. It needs some internal structure to help it hold shape. I’ve got a piece of balsa scrap doing the job now.
Pete
Edit: It’s morning, and I’ve had my coffee so I can babble about the hull a bit.
This is my first attempt at a design. I think I first heard of Footys on Jan 1, and I think I designed this hull on Thursday, though I probably started on Wednesday.
It is 1/64th ply except the transom. It is made in the style of a Razor but I went for a shape with the beam well forward to keep the bows from getting pushed under on a run. Never having seen a footy at all, let alone watched one sailing the vision of plowing the bows under on a run comes from what I know about cat rigged boats in general.
Not everything came out exactly as I wanted, but I am making templates each step of the way, so the second boat will go a lot faster than the first (in terms of construction) and will be a more accurate implementation of what I intend.
Never having built one of these I have a lot of questions but I do have enough background at modeling (airplanes) to find my own way through the basics.
I would have been done with the hull much sooner, but my boss hates the smell of CA and for some odd reason expects me to do certain non-hobby related things during working hours. He can’t keep me from thinking about what I want though!
I’ve got much more experience than you since I heard about Footy’s way back in mid December. Be sure to take any of my advice with a grain of salt. That said, Brett’s MacRig is a stroke of genius for a guy like me with no clue. I’m having a great time playing with my first boat (depron Razor) and trying some large high aspect rigs to see what happens. I’m still just using the original mast foot and boom even with wild variations in sail size. The wire is a stainless steel bicylce spoke. The flex absorbs any abuse I throw at it and still allows the boat to keep it’s bow from submerging, though it does come close on occasion. Keep up the good work.
Thanks Brent. I already raided your Razor thread for ideas and early on someone directed me to the Mcrig, which is wonderfully logical. I have bicycle spokes (in fact, whole bicycles, but it’s easier to just use a spoke out of the package) and a few sizes of carbon fiber rod and some tubing. I ordered some more stuff from Hobby Lobby including metric brass tubing with a 2.1 mm inner diameter.
I got a rough idea of the size of the rig from your thread, so that is where I will start.
I just got home with two servos from a bunch in my flying buddy’s house. I am going to try an HS 85 for the sail and an HS 55 for the rudder. I think I would like something stronger for the rudder, but this will do for now.
The rudder servo has a relatively easy life - especially if you give the rudder some hydrodynamic balance - make the pivot about 25 to 35% back from the LE.
If you hang it from the transom - give it a bit of balance below the hull
I feel that a HS55 is fine - a concept I am working on will use a couple of 3.5 gm parkflier servos for rudder and rig
I can see moving a balanced rudder with anything, but I am really curious about controlling the rig with a tiny servo. I have a few Blue Arrow servos around and they fly my pico Tiger Moth just fine, but the only way I can see to control a rig with a tiny servo would be to use it to control an anti servo tab on a rigid wing sail.
Hey… I think I’ll try that! Actually, L. Francis Herreschoff wrote about rigid wing sails in the thirties or so and there is a bit about the idea his “The Common Sense of Yacht Design” which I have around here someplace.
Edit: I think what I wanted to say is servo controlled trim tab. An anti servo tab is used to give feel to all flying stabilizers. (Probably could do the same job on a balanced rudder.)
If you see my previous post and replace the woard Water with Air, and hydrodynamic with areodynamic - the same applies.
The MacRig effectively puts the pivot close to the aerodynamic centre of the rig, so the forces to change it are small and (relatively) well balanced. There has been discussion of the front/back attachment advantages but (I think) the lesson was that we a want a small amount of imbalance so that at least the rig will always proceed to a known position - not go overcentre the other way.
Also we can control a Macrig with small movements of the sheet - both mine are using a straight pull from above-deck servos and short arms
I’ve started to do it but run out of time - but …
People keep wailing about what torque do I need from my servo. The question is meaningless. The relevant number is probably something like the ratio of applied force (from sail) to applied force power (from servo).
I get the distinct impression that nobody in this discusion has any problem in understanding that the detailed geomety of the sheeting system has a huge effect on this. If someone has the time and the fairly simple geometric expertise to produce a very basic simulator on a spreadsheet of different geometries, it would be a huge benefit to a lot of people.
Worth a try, but there are limits to balance also.
The Wright brothers believed that the pilot should be in control of the airplane and on the first flyer they made (the one at Kittyhawk) they used balanced control surfaces. The elevator was too sensitive and if you read accounts of the other flights that day they eventually damaged the airplane because of the overly sensitive elevator.
We won’t know until you try it, but right now the HS 85 looks good to me.
Best of luck when you try it. For myself, now that I remembered the rigid wing sail maybe I should give that a try. Set up McRig style there is no reason why it shouldn’t work well. This is a development class after all!
Maybe this post belongs in the Radical Footy thread.
Be sure to take any of my advice with a grain of salt. That said, Brett’s MacRig is a stroke of genius for a guy like me with no clue. I’m having a great time playing with my first boat (depron Razor) and trying some large high aspect rigs to see what happens. I’m still just using the original mast foot and boom even with wild variations in sail size. The wire is a stainless steel bicylce spoke. The flex absorbs any abuse I throw at it and still allows the boat to keep it’s bow from submerging, though it does come close on occasion. Keep up the good work.