So when surfing the web looking for outrigger plans, I came across this boat--the Cobra. Link is
http://www.john-tom.com/RCPowerBoats/RCPowerBoat.html (scroll down to see it).
Given my model airplane background, I couldn't resist, so away I went. I must say boats do seem to build faster than aircraft.
Anyway, it was designed as a catamaran but without a step in the hulls. Overall size is 35" long plus a couple of inches for the rudder and 15" wide at the widest point. It was designed for engines, so rpms would be limited to the 10-12K range, depending on the engine. Seemed like a good candidate for an electric to me, as I can use a high Kv outrunner on 5 or 6S with a small diameter high pitch prop--which should really make it move.
Given the beam, I felt it looked more like a hydro than a cat, so proceeded to make it more like one. I added a step, 1.5 inches in front of the CG, and also put a mini-sponson in the back, a la a rigger. I felt this should make the boat get up and go (pun intended). Given I am adding in what I expect will be more power via an outrunner, I decided to rename it to "Super Cobra"
Besides, if it doesn't run well, I can always convert the hull back to the original no-step cat design--but I don't think I will have to.
However, as I am not really a boat guy, I do have a couple of questions for input.
As shown in the picture, the boat has an air rudder that extends into the water. Should I maintain this, or maybe just go with a water rudder only (King of Shaves style rudder, maybe? or something else?) I think I at least want to keep the original if only for the looks, but if there is info that says otherwise, I do want to hear it.
The other picture shows a center mounted turn fin. Again, should I keep this? And since I expect performance to be jazzed up a bit over the original, should it be deeper? Plans show a fin that extends 1 3/8" below the hull. Again, my lack of FE experience shows, as I don't have a clue about turn fin size and depth.
Appreciate any input and opinions--and when I get it on the water, will be sure to mount a GPS and get a speed. Thanks…Pete M
http://www.john-tom.com/RCPowerBoats/RCPowerBoat.html (scroll down to see it).
Given my model airplane background, I couldn't resist, so away I went. I must say boats do seem to build faster than aircraft.
Anyway, it was designed as a catamaran but without a step in the hulls. Overall size is 35" long plus a couple of inches for the rudder and 15" wide at the widest point. It was designed for engines, so rpms would be limited to the 10-12K range, depending on the engine. Seemed like a good candidate for an electric to me, as I can use a high Kv outrunner on 5 or 6S with a small diameter high pitch prop--which should really make it move.
Given the beam, I felt it looked more like a hydro than a cat, so proceeded to make it more like one. I added a step, 1.5 inches in front of the CG, and also put a mini-sponson in the back, a la a rigger. I felt this should make the boat get up and go (pun intended). Given I am adding in what I expect will be more power via an outrunner, I decided to rename it to "Super Cobra"
Besides, if it doesn't run well, I can always convert the hull back to the original no-step cat design--but I don't think I will have to.However, as I am not really a boat guy, I do have a couple of questions for input.
As shown in the picture, the boat has an air rudder that extends into the water. Should I maintain this, or maybe just go with a water rudder only (King of Shaves style rudder, maybe? or something else?) I think I at least want to keep the original if only for the looks, but if there is info that says otherwise, I do want to hear it.
The other picture shows a center mounted turn fin. Again, should I keep this? And since I expect performance to be jazzed up a bit over the original, should it be deeper? Plans show a fin that extends 1 3/8" below the hull. Again, my lack of FE experience shows, as I don't have a clue about turn fin size and depth.
Appreciate any input and opinions--and when I get it on the water, will be sure to mount a GPS and get a speed. Thanks…Pete M
Anyway, have the rudder servo installation done and rails/velcro for the battery packs. I assembled it all to find out where I will need to put the packs to meet the CG, and also cut the top to allow access to same area. The front section that has the motor will be glued down, the last two thirds will be the hatch. Only assembly I have left to do is the centerline turn fin, and I have to add a couple of air intake scoops to the cowl (the exhaust tubes are functional and will be the air exit points). As noted, I am not going to install an air rudder, want to see how the standard water rudder will work, if it won't turn well I can always put it in later--it won't be hard to do.
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