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Articles on fans

How fast would 4 fans need to spin to float an RC car?
I want to make a sort of floating car out of an RC car. The fans will be relative to the size of the wheels. How fast would they need to spin just to float it a few inches?Let's say that the car weighs approximately 2 lbs., the diameter of the wheels fans is maybe 1 1 1 2 inches. Maybe there is also a fan in the middle of the bottom of the car about 2 inch diameter. I'm not worried about thrusting the car, just lift for now. What you think? A problem would be the battery pack for the fans, but don't worry about it. Only give me the necessary calculations for now, but if you can do it also with the extra pound, that would help. Thanks

The order of magnitude for total attendance for a professional football team that averages 70,000 fans for eac?
The order of magnitude for total attendance for a professional football team that averages 70,000 fans for each of its 15 home games is help.. its so fluffy, im gonna die

I have cooling tower with two motors which runs 3 fans can one VFD will control these two motors?

Electric heating appliances and fans?
1. In selecting the wire size for a line cord, you should remember thatA. No. 16 is larger than No. 12.B. No. 14 carries more current than No. 18.C. No. 8 is smaller than No. 10.D. No. 4 carries less current than No. 6. 2. Which one of the following appliance parts gets the hardest service?A. SwitchB. ThermostatC. Heating elementD. Line cord 3. The color used for the hot side of house wiring isA. green.B. white.C. gray.D. black. 4. An AWG No. 16 line cord with type HPN insulation has an ampacity ofA. 12 amp.B. 13 amp.C. 15 amp.D. 17 amp. 5. To heat a room quickly, some electric room heaters are provided withA. a heavy metal case.B. a motor driven fan.C. a push button switch.D. an automatic thermostat. 6. If the current flowing through an electric heater increases from 6 to 12 amp while the voltage remains the same, the heat produced by the heater will beA. reduced one half.B. unchanged.C. two times the original heat.D. four times the original heat. 7. The wires used in a heating element are usually made ofA. copper.B. steel.C. aluminum.D. Nichrome. 8. Why does a thermostat blade bend when heated or cooled?A. It is made of two different materials.B. There is a difference in temperature between the blade ends.C. Different currents are applied to each end.D. Mechanical pressure is caused by the high resistance. 9. When you are checking an electric heating appliance, the first test made should be forA. excessive leakage.B. the normal voltage supply.C. an open circuit.D. low resistance. 10. Why should you NOT repair heating elements by soldering?A. Solder does not conduct electric current.B. Solder joints are mechanically too weak.C. Solder melts at the operating temperature of the heater.D. Soldered joints have too high a resistance. 11. What type of selector switch can be used to control the heat output of three elements connected in parallel?A. SPST switchB. DPST switchC. DPDT switchD. Shorting bar type switch 12. Thermostats used in electric irons differ from those in small room heaters in that they areA. smaller in size.B. operative at higher temperatures.C. connected directly to the appliance plug.D. mechanically more fragile. 13. How can you clean out the scales in an electric iron without taking the iron apart?A. By blowing out the holes with compressed airB. By scraping the tank and tubes with a drill bitC. By brushing the clogged tubes with a stiff wire brushD. By rinsing the tank and holes with a water diluted chemical 14. Bus bars are used in an electric iron asA. thermostat supports.B. heat adjusting resistors.C. connectors between the thermostat and the element.D. electrical terminals. 15. The water in a spray iron is prevented from returning to the tank by the action of aA. suction tube.B. check valve.C. water pump.D. pressure spring. 16. The heating element in an electric iron is in good working order if the resistance across the terminals of the element reads approximatelyA. 0 ohms.B. 15 ohms.C. 120 ohms.D. 1000 ohms. 17. Why does the heat of the heating element stop when the desired temperature in an electric iron is reached?A. The thermostat blade opens electrical contacts.B. The circuit through the element is closed.C. The switch bypasses the thermostat.D. The contacts on the blade touch. 18. Jumpering out the resistors in a resistance controlled three speed fan will cause the motor toA. run at highest speed.B. run at medium speed.C. run at lowest speed.D. stop immediately. 19. A fan equipped with a gearbox is capable ofA. running at three speeds.B. being tilted downward.C. oscillating from side to side.D. reversing the direction of the motor. 20. If the fan blades rattle while the fan is turning, you can stop the noise byA. oiling the blades.B. adjusting the blade angles and the blade tip position.C. tightening the motor end bells and motor mounts.D. cleaning the blade surfaces. 21. The recommended way to hold a loose hub on a fan is byA. riveting.B. soldering.C. welding.D. cementing. 22. Quiet operation of a fan depends mostly upon theA. weight of the blades.B. material of the blades.C. motor balance.D. balance of the blades. 23. The blades of small fans are made ofA. aluminum.B. steel.C. tin.D. copper. 24. A modern variable speed fan does NOT useA. a tapped inductor.B. a multiple winding motor.C. an electronic speed control.D. a dropping resistor. 25. An attic fan, or power ventilator, may have its power inadvertently tapped fromA. an upstairs bathroom.B. an attic lighting circuit.C. a basement service.D. an air conditioning circuit.

Two thirds of the game attendees were fans of the home team.If 600 people attended the game,how many were fans?

What is the procedure for flow measurement of centrifugal fans?
if any flow sensor like MAF or variband can able to measure it,

How are alluvial fans related to sedimentation?

Multiple pc fans stronger?
If multiple pc fans where lined up , would more pull push force be generated?Air flow in > >

Is it true that if you have a fan on for an extended period of time it will throw "hot air"?
I have often heard that people should turn off box ceiling fans slim fans off after certain amount of time because they will only throw out " hot air" . Is this true or what?