R/C Naval Combat

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Originally posted by crzyhawk

I just talked to Mikey, and he said the spirit of the rule was to keep people from trying to "beat the rules" so to speak and crank up their thrust to enable better turning. So, we've never really tested that part of the rule, and if it's a problem is something that's
I'm wasting a lot of amp hours on my batteries right now. It's time to start looking at efficiency so I can run the same batteries for longer periods of time.

Your going to find that even running that slow you wil run into major effiencey iisues. The displacement of the model and the water density will still draw the same demands on the motors. Hence smaller motors will have a greater demand and this will rob smaller battereis and the motors of power.

Less thrust from the props at slower speeds will greatly affect your model's ability to turn. The lighter models sit not as deep in the water so drag is not as great anything above 10lbs is going to have performance issues. The BG style compensates for the drop off in turning by having Rotating guns to offset that issue. The issue here is the guns are fixed but your running these models at BG speeds.

PE in fast gun that I just completed weighs 18lbs, runs dead on 28 secs on direct drive using a pair of BC's 380 motors, wired in pararelle.The props are BC's smallest 4 blade 25 pitch. I find the 25 pitch works well in slowing down the model but still allow plenty of thrust over the rudder via it single tandem or dual to allow maneuverability . The props are near scale size but they make up for it by having direct power applied which provides the power to push the weight of the model through the water without overcompensating and causing the model to exceed it's speed. In turn the motors are not overworking becasue the props still have a good bite but less resistance than a standard prop that most guys use. I can still maximize battery power to provide plenty for a large pump that the larger ships use and still have a very long duration for combat.

Using ESCS to slow your ships down in this format presents another issue.. they will still waster power. Slowing down the motor the esc has to get rid of the excess pwr. Not the most effiecient system particulary at these lower speeds. Reduced voltage means less power.

You can see there are a lot of compromises to get these ships down to these speeds. Unfortuatly anything greater than 10lbs will begin to have efficency issues. The environment the models operate under is not a scaled down environment. If the models were operating to a scale density of the water it would be like running the ships in a liquid medium such as gasoline to create the scale speed and hydrodymamically flow around the hull. That said though the equivilant now is akin to running through liquid JELLO.

The Treaty format slow speeds may work for the much smaller lighter ships were the smaller motors will not be overtaxed moving the lighter displacent with less hull resistance and less resistance from a smaller prop through the water. It will take a sometime of trial and error to find the right combo of power,motor,pitch, prop size, battery weight, battery power and amperage to make a effiecient treaty model without exceeding the speed forward. Using drag props, escss ect will affect effiecncy however may be necessary. Try the scale props with direct power and flatter pitch. Even with a esc the smaller prop will turn over faster than a larger one.May be able to give you speed and performance at these lower speeds.

If the treaty ships are runiing BG speeds the BG guys will have info on their drive trains and power supplies that should help with the new treaty ships. Will save a lot of time and work to get these ships up and running.

Anybody have a completed large Treaty Ship like a NC or Sodak completed? How does it perform? Any info will help.

[:)]

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