Scale boat questions
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BullDogRacing
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Gaday Brian
Mate to put thing in to prospective my
OPS used 16 oz around Penrith race conditions
CMB moded by Aaron used 20oz
Mac in my t4 ive been told to pack 22oz min - 24oz .
Now days all my new deals have 2 x 12oz tanks
Steering servo 5955 tg Hitec
Brad
Mate to put thing in to prospective my
OPS used 16 oz around Penrith race conditions
CMB moded by Aaron used 20oz
Mac in my t4 ive been told to pack 22oz min - 24oz .
Now days all my new deals have 2 x 12oz tanks
Steering servo 5955 tg Hitec
Brad
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Hydro Junkie
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Fuel requirements are normally dictated by the fuel nitro content, how rich you run, boat weight and set up. Brad also brings up a good point about different engines and/or engine/pipe combos using different amounts of fuel as well. Since most run 50% or higher fuel, 20 ounces is NORMALLY a safe minimum to start from. That being said, I've seen boats running 16 to 18 ounce totals that the driver waits until the last minute to launch to keep weight down as well as boats that do require the 24 ounces Brad recommends so it's kind of a hit or miss deal. My recommendation would be to run the boat as you would in an actual heat, putting yourself on the clock, and see how much fuel you use running an extra two laps, adjusting your fuel load appropriately so you won't have a lot left in the tanks but you're not down to fumes either.
As for servos, look for metal gears and no less than 90 oz-in of torque. This is a case where more is better as you're not going to hurt a heavier duty servo by underloading it but a lighter servo may not last long if it's overloaded.
As for servos, look for metal gears and no less than 90 oz-in of torque. This is a case where more is better as you're not going to hurt a heavier duty servo by underloading it but a lighter servo may not last long if it's overloaded.
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glenng
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Bryan, I've always shoved the motor as far forward as I could and build the rear of the boat as light as I could and always end up with the balance point 1/2 to 3/4 inches behind the sponson transoms. I've heard the Picco motors were not as fuel thirsty as the CMB's but what if you decide to use a CMB in the future??? As for steering servos I liked the Airtronics 200 Oz. std. size Analog servos but they have been obsolete for a while- seems everyone is going to digital.
Dasboatman
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Hey Bryan,
I would suggest that you plan for 24 oz. of fuel. Logic: It's easier to short fuel if you're concerned about weight then find a place for the 3 ounces you find yourself short. My first Scale boat had an OPS 60 stock carb - 12 ounces was plenty. I later put an OPS 80 slide carb on the engine and had to cut into the hull for a 16 oz. tank. Run 16 oz. tank in my Oberto with PICCO EXR silver head in it. CMB Green heads are thirsty beasts. My Buddy is carrying 20 oz. of fuel - can launch early and has fuel left at end of run. The first one I built for a green head had tanks for 22 oz. I thought I'd learn from past experience and get 2 oz. ahead of the trend.
Engine placement will vary hull to hull. I would suggest you mount your engine in the motor mount then decide what tanks you'll use and where you want them. Figure out what size radio box you need and position everything in a mocked up 'rough' container. This will pretty much determine where everything will be positioned in the hull. I think you'll find that you run out of room for expansion in a Scale hull very quickly. "Proper Prior Planning Prevents Piss Poor Performance" - - the 7 Ps Theorem always applies.
Servos: I personally prefer Airtronics servos for rudder, I use only Futaba for everything else. I have had issues with Hitec over the years. I had three 1/4 scale servos fail during consecutive test sessions, while trying to get a Classic Thunderboat ready for the 2010 NAMBA Nats. I put a Futaba S5301 in and haven't had any more problems. Side note - - the HITEC servos did not float when I threw them toward the middle of the lake. CHEERS !!! Bob
I would suggest that you plan for 24 oz. of fuel. Logic: It's easier to short fuel if you're concerned about weight then find a place for the 3 ounces you find yourself short. My first Scale boat had an OPS 60 stock carb - 12 ounces was plenty. I later put an OPS 80 slide carb on the engine and had to cut into the hull for a 16 oz. tank. Run 16 oz. tank in my Oberto with PICCO EXR silver head in it. CMB Green heads are thirsty beasts. My Buddy is carrying 20 oz. of fuel - can launch early and has fuel left at end of run. The first one I built for a green head had tanks for 22 oz. I thought I'd learn from past experience and get 2 oz. ahead of the trend.
Engine placement will vary hull to hull. I would suggest you mount your engine in the motor mount then decide what tanks you'll use and where you want them. Figure out what size radio box you need and position everything in a mocked up 'rough' container. This will pretty much determine where everything will be positioned in the hull. I think you'll find that you run out of room for expansion in a Scale hull very quickly. "Proper Prior Planning Prevents Piss Poor Performance" - - the 7 Ps Theorem always applies.
Servos: I personally prefer Airtronics servos for rudder, I use only Futaba for everything else. I have had issues with Hitec over the years. I had three 1/4 scale servos fail during consecutive test sessions, while trying to get a Classic Thunderboat ready for the 2010 NAMBA Nats. I put a Futaba S5301 in and haven't had any more problems. Side note - - the HITEC servos did not float when I threw them toward the middle of the lake. CHEERS !!! Bob
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Unless you are really running too rich a16 oz. main and 2 oz. sump should be plenty even if you get a penalty. This assumes of course you are not running wide open during the mill.
Most 1/8th scale boats work well with about 1 1/2 lbs of prop weight as a starting point. Block up the back of the sponsons and install a prop and put it on a fairly accurate scale. Install the motor in the mount with the isolators, header, pipe, muffler, coupler w/hose clamps, completed radio box with battery, pushrods, tanks (plumbed with tubing and stoppers) rudder, turnfin bracket, turnfin, cowling and wings, fake engine and any hatches, stuffing box materials, cable with ferrule, strut stub shaft, collar, drive dog and usually at least 10 oz. of lead on the left sponson. You can pile all that inside the boat. Basically everything the completed boat will have. Start moving the motor forward and back until you get to around the 1 & 1/2 lbs. of prop weight. When you lift the boat from under the deck webbing at the back of the sponson transoms the boat should have about 3-5 degree up angle at the bow. You will be really close at that point assuming the boat doesn't have outrageous angle of attack on the running surfaces, a really radically steep break in the bottom or weigh as much as the real boat. Boats that do have high angle of attack running surfaces or steep breaks that cause the boat to trap too much air and you will probably have to shift more weight forward so it doesn't end up being a kite.
You can also block up the prop, one running surface and check the side to side weight.
Most 1/8th scale boats work well with about 1 1/2 lbs of prop weight as a starting point. Block up the back of the sponsons and install a prop and put it on a fairly accurate scale. Install the motor in the mount with the isolators, header, pipe, muffler, coupler w/hose clamps, completed radio box with battery, pushrods, tanks (plumbed with tubing and stoppers) rudder, turnfin bracket, turnfin, cowling and wings, fake engine and any hatches, stuffing box materials, cable with ferrule, strut stub shaft, collar, drive dog and usually at least 10 oz. of lead on the left sponson. You can pile all that inside the boat. Basically everything the completed boat will have. Start moving the motor forward and back until you get to around the 1 & 1/2 lbs. of prop weight. When you lift the boat from under the deck webbing at the back of the sponson transoms the boat should have about 3-5 degree up angle at the bow. You will be really close at that point assuming the boat doesn't have outrageous angle of attack on the running surfaces, a really radically steep break in the bottom or weigh as much as the real boat. Boats that do have high angle of attack running surfaces or steep breaks that cause the boat to trap too much air and you will probably have to shift more weight forward so it doesn't end up being a kite.
You can also block up the prop, one running surface and check the side to side weight.
D
Douglas P Shepherd
Guest
I sure could not make it on 18oz of fuel. I must run very thristy Green heads. I need a min of 22 oz and that does not leave me with ANY to put back in the bottle . So I would put 24 oz's capacity of fuel and not look back.
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Yeeeupp, Picco 67exr your good at 18 oz., CMB 67 Greenhead, build for 24, that extra lap you do is going to need it..................
SayMikey
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Mike Runs RCU and NWS they dont race 6 laps except for the final........My boat needs 18 min make it 22 and use it for ballast moving the tank where you need it... Most of the time its right up next to the motor mount
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