Recent content by JonasS

I have been working on something similar...replacing the engine in an ultralight with an AC motor. So I have been looking at flight physics a lot. I have found plenty of help on remote control sites, since many RC planes use electric motors. There is a commonly used formula by Bob Boucher...

Okay, a slight change to what I posted above: What this is telling me is that pushing the motor in this way does not drain the voltage source faster. Going from 60Hz to 120Hz will not drain the battery pack any faster. However, going from 60Hz to 30Hz will not save you any power, since the...

Okay, I have been digging up everything I can find online about this, and while nobody here was a huge help it turns out that averagesupernova was the one who was sort of correct. It is true that when you use AC motors the ratio between voltage and frequency should be kept at a constant...

Trust me, I have read just about everything there is to read about AC motors recently, and I have a very good understanding about how they work. Problem is, Super seems to be right. I have just found several articles that talk about keeping the voltage/frequency ratio constant as the...

My question isn't about the fan. My question isn't about gear ratios. My question is about AC motors, and I still do not understand what voltage and current have to do with anything if the speed of the motor is based solely on the frequency of the AC power. Let's see if I can make the...

Power = Torque x rpm I agree that I am just not getting something. Doesn't the speed at which the fan turns dependent on the speed of the rotor...which is dependent on the AC frequency? Power just determines how quickly the fan will accelerate, right? :confused: Okay, here is a real...

Well let us say it is the same load...a fan...for both instances. If the load, which I assume means the torque needed to spin the fan, stays the same at both 60Hz and 120Hz then how can it drain more power?

Hello all. I have a question about AC motors that has been driving me crazy. I understand how variable frequency drives work, by adjusting the power frequency and thus changing the rpm of the motor based on the equation: rpm = 120 x f / p where f = frequency (Hz) and p = number of motor...

Okay, just a little confused... I know that the buoyant force is F=dgv but I am confused as to why I would not use the air inside the cup when calculating volume. Let's say I use plastic wrap to seal the mouth of the cup, and perform the same experiment. Wouldn't you then use the air...

I was looking for information on calculating buoyancy of an upside-down cup in a bathtub... If I place a plastic cup upside-down in a bathtub and press down, the water goes up into the cup a certain distance depending on the force I press down. Does this mean that the pressure of the air in...

Arg, of course I meant orbital velocity. Darn sausage fingers won't do what I tell em. ;) Well, my numbers finally make a little sense. At the point where the shuttle reaches "orbital" velocity of 8046.67m/s it is at an altitude of 109.26km and has moved downrange from the launch point...

Yea, I really love this stuff. But my confusion continues. Regardless of any other data, the simple fact is that the space shuttle reaches a speed of 8046.67m/s in 510s...with an initial velocity imparted to it by the Earth's spin of 408.89m/s. To me, that means an average acceleration of...

Some more data Looks like I also left out the 1472km/h acceleration imparted by the Earth's rotation. I'll have to factor that in and recompute. Also, I have been trying to figure out the actual distance traveled by the shuttle during launch. I used altitude as "s" in my previous...

1. I know, the calculations for t=120 and t=510 would be average accelerations. 2. Ah, forgot about that. That makes the 15.78m/s2 number seem better. 3. I'm not talking about orbit here, only launch/ascent to "edge of space" at ~100km.

Hello all. I am doing some research on the space shuttle for a class project, and I am having some problems with my data. I was hoping someone could show me the error of my ways. I got all of my data from this site: http://spaceflight1.nasa.gov/shuttle/reference/basics It says that 2...