Thread: Using Motocalc
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Old 05-10-2014, 08:28 AM   #1
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Default Using Motocalc

So I was playing around with Motocalc, came to around 17oz for empty weight of the P47. I don't have a scale that can measure it properly, but I took the max of what the plane likely would be (24 oz) and subtracted the weight of the battery, motor and esc. No specs on area of wing, but it is somewhere around 300sq in I gather (the Mini Switch is around 170, and the the P47 has a larger span and clearly a larger area distance from the leading to trailing edge. Putting it at 250 changes results very little. I found the specs for the motor, an RCtimer 2830/11 1000kV, including resistance, weight. I also found the specs for the battery, although under cell weight, I gather the program asks for individual cell, so I divided the weight by 3 for the battery. The results that I got were stall speed until 18mph, level flight at clopt=0.53 25mph (whatever that means), 29mph level flight at Cl=0.4 and a max airspeed of 44mph. Now, my specs are obviously not accurate completely. I know how to find the wing area, but it isn't that far off. As for weight, that may make a difference, but I'm thinking of the answer to my question: Does the front end of the P47 really suck the plane back that much, or am I running much too heavy (not sure what it would be other than 2 retracts, and a bit of extra sheeting on the wings). These results are a 10x6 prop. All going up to a 10x8 prop does is increase the top speed to 53mph, would this have helped me quite a bit you think? I would have achieved the 10x6 max airspeed at 75% throttle according to this. Now here is what I am confused about, an 11x8 prop has nothing different than a 10x8 prop...what does that mean? I really want to get down to figuring this prop stuff out, I am tired of crashing because of screw ups on my part of installing the wrong props. My own flying mistakes, that is fine, but not mistakes before I fly.
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