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This is kind of following on from the recent IMPBA Scale thread that I don't want to clutter up with off topic discussion.
The first unlimited I saw pictures of in a magazine was the Tide, it was love at first site. A few years ago an IC boater I know built one and made molds for epoxy glass parts, to cover his costs he wanted to sell a few, so I bought a wing and canopy set from him. About a year later my dad died and amongst his designs I came across a set of newton plans for the Tide.
I will soon have some time on my hands and would like to start building it, but my budget is tighter than ever so it won't get a huge motor or ESC.
I know of only 3 other FE 1:8 hydros in the UK, there is no racing class for them and I have never seen more than one at a time so I have no rules to run to.
Firstly are the Newton plans for a clockwise course or anti clockwise, I would like clockwise as all my other oval boats are clockwise and if I built it for anticlockwise it is only a matter of time before I forget and crash trying to go clockwise.
My MPBA insurance will cover me to 14s, but while 14s would be ideal, I already have a 120A 12s ESC, and I have lightweight 6s packs for my race boats, so it will be run on 12s. I like to run my ESCs with the peak amps at the rating not the constant amps for reliability, so I probably have around 60-70A, constant to play with (about 3KW). I know it is not much compared to even those limited to 1527s in the states, but my Naviga endurance racing background has taught me that I can go fast with little power as long as the weight is kept low. My 200w 500g, 500w 1kg, 1kw 2kg, and 2kw 4kg race boats go very well, so if I can get to come in at about 6kg (13.2lb) I am sure I will be very happy with the performance.
I think the power system will be TP 4060 455g, Turnigy K-force ESC 130g, 12s1p Redzone 4800, ETTI 4500, or zippy compact 4000 1120g, Ubec 25g, a 2.5mm wire drive with minimal stuffing tube stainless strut and a BeCu prop around 50mm 75g, an alloy set screw coupler 11g, 160mm rudder 120g, Hobbyking 20kg coreless servo 66g. Not made yet but probably along the lines of 60g water tubes, 50g water jacket, 20g safety loop, 20g alloy strut brackets, 15g servo linkage, 40g motor mount, that is a total of 2207g (4.9lb) for power system and running hardware. My glass parts (canopy, engine housing, wing, wing uprights, canard and saltwater snorkel) come to 813g, which brings the total up to 3020g (6.6lb). That leaves 2980g (6.6lb) for the hull, exhaust pipe, wing support struts, paint/decalwork and cockpit/driver (assuming I don't cop out and paint the windscreen on).
I have heard 17 and 18lb boats being described as heavy, and a 20lb boat as being uncompetitive within the rules, but I have no idea what is considered light for a modern 1:8th, how light is a light modern 1:8th? Do you think 13lb is feasible, given the weights above?
I don't really know what I am doing with a plywood boat, all the previous boats I have made bar one that was barely FE that I made as a kid have been balsa, WoF, Composite, someone else's kit (and I thought most of there kits were excessively heavy). I know I could get it down to weight making it from balsa, but I want a tough ding-proof skin which will have good aesthetics for some years to come on this one, unlike my raceboats that will be thrown away and replaced with a new design after a short while. I am sure I could carve a plug, make a mould and lay up a composite boat light enough too, but it would cost a bundle for a boat this size. If I use the materials suggested in the plans I think I would end up with a disappointing pig, if it would even get up on the plane.
I am trying to think of relatively cheap ways to build one using plywood methods ala the plan but lighter. How are those with lightweight 1:8th scales building theirs?
I have done carbon/balsa/carbon and glass/balsa/glass composites as transoms and motor mounts before so I will use those for the bulkheads, but while it is very strong for the weight it is not very dingproof unless a thick and heavy outer layer is put on which negates much of the weight advantage for a skin.
I don't know what to use for a skin, glass/balsa/1-64th, could be as strong as 1-16 but lighter and glass/balsa/carbon/glass equally so but would be a PITA to finish, a single layer of thinner ply would be by far the cheapest, and by far the easiest but also much weaker 1-32 being half the weight of the 1-16th ply suggested and less than half the strength, it may be OK with it being a lighter boat and having no IC vibrations, but maybe not, I have 1mm ply available here too, which is a little thicker (half way between 1-32 and 3-64). I also Have some Depron that I could substitute the balsa with, which would be cheaper, lighter and comes in bigger sheets, but I have never used it for this sort of thing and am not sure it will curve over bulkheads as well as wood will, so I am afraid of getting a starved horse look and the edges would have to bevel both ways for skin to skin contact as unlike balsa you cant stiffen the edges up by soaking epoxy in so the build would be much more difficult.
Has anyone used any of those methods before or have any opinions on them, or on the strengths of the thinner plys? Or have any recommendations for alternative skins?
Any thoughts on the strength difference, or weight difference between hollow 1/16 ply skin, and 1/32 ply skin over white foam flotation?
The first unlimited I saw pictures of in a magazine was the Tide, it was love at first site. A few years ago an IC boater I know built one and made molds for epoxy glass parts, to cover his costs he wanted to sell a few, so I bought a wing and canopy set from him. About a year later my dad died and amongst his designs I came across a set of newton plans for the Tide.
I will soon have some time on my hands and would like to start building it, but my budget is tighter than ever so it won't get a huge motor or ESC.
I know of only 3 other FE 1:8 hydros in the UK, there is no racing class for them and I have never seen more than one at a time so I have no rules to run to.
Firstly are the Newton plans for a clockwise course or anti clockwise, I would like clockwise as all my other oval boats are clockwise and if I built it for anticlockwise it is only a matter of time before I forget and crash trying to go clockwise.
My MPBA insurance will cover me to 14s, but while 14s would be ideal, I already have a 120A 12s ESC, and I have lightweight 6s packs for my race boats, so it will be run on 12s. I like to run my ESCs with the peak amps at the rating not the constant amps for reliability, so I probably have around 60-70A, constant to play with (about 3KW). I know it is not much compared to even those limited to 1527s in the states, but my Naviga endurance racing background has taught me that I can go fast with little power as long as the weight is kept low. My 200w 500g, 500w 1kg, 1kw 2kg, and 2kw 4kg race boats go very well, so if I can get to come in at about 6kg (13.2lb) I am sure I will be very happy with the performance.
I think the power system will be TP 4060 455g, Turnigy K-force ESC 130g, 12s1p Redzone 4800, ETTI 4500, or zippy compact 4000 1120g, Ubec 25g, a 2.5mm wire drive with minimal stuffing tube stainless strut and a BeCu prop around 50mm 75g, an alloy set screw coupler 11g, 160mm rudder 120g, Hobbyking 20kg coreless servo 66g. Not made yet but probably along the lines of 60g water tubes, 50g water jacket, 20g safety loop, 20g alloy strut brackets, 15g servo linkage, 40g motor mount, that is a total of 2207g (4.9lb) for power system and running hardware. My glass parts (canopy, engine housing, wing, wing uprights, canard and saltwater snorkel) come to 813g, which brings the total up to 3020g (6.6lb). That leaves 2980g (6.6lb) for the hull, exhaust pipe, wing support struts, paint/decalwork and cockpit/driver (assuming I don't cop out and paint the windscreen on).
I have heard 17 and 18lb boats being described as heavy, and a 20lb boat as being uncompetitive within the rules, but I have no idea what is considered light for a modern 1:8th, how light is a light modern 1:8th? Do you think 13lb is feasible, given the weights above?
I don't really know what I am doing with a plywood boat, all the previous boats I have made bar one that was barely FE that I made as a kid have been balsa, WoF, Composite, someone else's kit (and I thought most of there kits were excessively heavy). I know I could get it down to weight making it from balsa, but I want a tough ding-proof skin which will have good aesthetics for some years to come on this one, unlike my raceboats that will be thrown away and replaced with a new design after a short while. I am sure I could carve a plug, make a mould and lay up a composite boat light enough too, but it would cost a bundle for a boat this size. If I use the materials suggested in the plans I think I would end up with a disappointing pig, if it would even get up on the plane.
I am trying to think of relatively cheap ways to build one using plywood methods ala the plan but lighter. How are those with lightweight 1:8th scales building theirs?
I have done carbon/balsa/carbon and glass/balsa/glass composites as transoms and motor mounts before so I will use those for the bulkheads, but while it is very strong for the weight it is not very dingproof unless a thick and heavy outer layer is put on which negates much of the weight advantage for a skin.
I don't know what to use for a skin, glass/balsa/1-64th, could be as strong as 1-16 but lighter and glass/balsa/carbon/glass equally so but would be a PITA to finish, a single layer of thinner ply would be by far the cheapest, and by far the easiest but also much weaker 1-32 being half the weight of the 1-16th ply suggested and less than half the strength, it may be OK with it being a lighter boat and having no IC vibrations, but maybe not, I have 1mm ply available here too, which is a little thicker (half way between 1-32 and 3-64). I also Have some Depron that I could substitute the balsa with, which would be cheaper, lighter and comes in bigger sheets, but I have never used it for this sort of thing and am not sure it will curve over bulkheads as well as wood will, so I am afraid of getting a starved horse look and the edges would have to bevel both ways for skin to skin contact as unlike balsa you cant stiffen the edges up by soaking epoxy in so the build would be much more difficult.
Has anyone used any of those methods before or have any opinions on them, or on the strengths of the thinner plys? Or have any recommendations for alternative skins?
Any thoughts on the strength difference, or weight difference between hollow 1/16 ply skin, and 1/32 ply skin over white foam flotation?
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