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Homemade Computer Fan Helicopter?

Discussion in 'Robotics & Mechatronics' started by Krumlink, Sep 13, 2007.

  1. Krumlink

    Krumlink New Member

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    This is just an Idea I have been throwing around, but is it possible to create any form of lift from Brushless DC motors? If so, What should I use? I want to try this, this would be cool. I could add Helium Stability Modules for some assistance of lift, but that is it. If this works I will Make this a contest. This will be cool.
     
  2. dknguyen

    dknguyen Well-Known Member

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    THe fans don't put out enough thrust to lift their own weight (obviously) so that won't work. Better to use helium to lift everything and the fans to move it around.
     
  3. Sceadwian

    Sceadwian Banned

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    If you don't mind trying and burning out a few fans overvoltage them. This works best with brushed motors, never tried it on brushless but there has to be some allowance for higher voltages. You might be able to get short bursts of thrust enough to lift it briefly. Sounds like something fun to test with a variable power supply. Try increasing the voltage a half volt at a time every 2 or three minutes, and when the fans start burning out (or you smell smoke =>) run the fans at a slightly lower voltage than the failure point.
     
  4. dave

    Dave New Member

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  5. kchriste

    kchriste New Member Forum Supporter

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    For $20 you can go to WalMart and buy one of these:
    http://www.redflagdeals.com/forums/showthread.php?t=460124
    Hard to control, easy to break, but it's only $20 ;)
     
  6. Sceadwian

    Sceadwian Banned

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    Not nearly as much fun as trying to get a PC fan off the ground =)
     
  7. kchriste

    kchriste New Member Forum Supporter

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    Last edited: Sep 13, 2007
  8. Leftyretro

    Leftyretro New Member

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    RC hobbyist have been using brushless DC motors for years in electric helicopers of several sizes. Real limit is the weight/costs/duration for the batteries. It's not a cheap hobby but their are real high performance electric helos out there. A real challenge to learn to fly without direct mentor help.

    Lefty
     
  9. Hero999

    Hero999 Banned

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    I've managed to make a motor take off before.

    I used a carbon brushed motor and a cheap and nasty propeller I borrowed from school (we were using it to make elastic band driven aircraft). The motor flew about on the end of the wire for a few seconds before spiralling out of control and breaking the propeller on my bed post.

    The problem is a helicopter needs another propeller on the back to counter the turning force and the blades on the main thruster need to have a continuously adjustable cutting angle.
     
  10. HarveyH42

    HarveyH42 Banned

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    Couple of years ago, I was given a Blade CP helicopter for christmas, hard as hell to fly. On a good flight, I might keep it in the air for 20-30 seconds, and its very stressful. Two weeks ago, I bought a duel rotor Reflex helicopter cheap (factory reconditioned). Easy to get in the air and hover, but not much direction control (defective perhaps). Very stable in the air though, and tough too, crashed it dozens of times and no damage yet.

    I learned that it's best to get off the ground quickly. Wind from the rotor makes it tough to gain control, or even predict what direction it might take initially. Also, even a light breeze is a bad thing for small helicopters, maybe not so bad with more experience.

    If you have never flown a helicopter, it's not an easy thing to learn. Start cheap, you will crash and repair a lot. Definately consider the dual rotor designs, only had one relatively calm day with the Blade since playing with cheap Reflex, but it went a lot smooth getting it off the ground.
     
  11. ThermalRunaway

    ThermalRunaway New Member

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    The blades on a PC fan are not ideally suited to the application of creating lift, are they. What if he used the motor and assembly of a PC fan but cut off the blades and make some that are more fit for the purpose?

    I can't offer advice on how to engineer the blades though. You'll need to do some research on that.

    Brian
     
  12. Hank Fletcher

    Hank Fletcher New Member

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    I've already been down this road of modifying a PC fan for any purpose other than cooling, and I hate to be a downer, but it's a fruitless quest. PC fans just can't generate enough useful thrust, and have a poor power-to-mass design.

    It's excusable because they're not designed to provide thrust, but to slowly move a volume of air over your computer. If they were more powerful, it'd be like having a vacuum sucking all kinds of bits into your computer (which happens with dust over time anyways).

    Even lower thrust applications like a hovercraft or blimp are too much for a PC fan. The blimp might work, but for the hassle for what you would get out of it, you'd be better off going for a motor initially designed for the purpose.
    To give you an idea, a PC fan didn't even provide enough thrust to be used for my recorder robot, which requires extremely little thrust.

    I'd guess an analogy for thrust to electonics hobbyists would be that to voltage. It doesn't matter if the fan's moving a large volume of air (current), if the thrust (voltage) is low, when the air encounters any kind of resistance (resistance) the air flow (current) will fall to zero.

    It's a bummer, because there's obviously a surplus of computer fans all over the place. My advice is to get creative about using them for other cooling applications (i.e. mount one over your high-powered ICs).

    If I had to go MacGyver and build my own electronic helicopter, I'd probably start with the pre-made blades on those hand-driven propellers. They're simple, but hard to describe, so I hope you understand what I mean. We sometimes get them as stocking-stuffers at Christmas. It's just a wooden dowel (about a 1/4") with a propeller about 6" across on the end, and you put the dowel between your flat hands and move them quickly in opposite directions. That generates enough lift to send the toy on a five second spin around the room. You can probably pick them up at a dollar store - they'd be cheap props, anyway, so you'd be able to justify breaking a few during the course of experimenting. I'd wager a $2 DC motor, pulley and belt drive, the prop, and a small battery pack would be able to power themselves off the ground. Definitely would work well as a drive for a blimp.

    edit: Scratch the belt-drive. My parents recently brought up a load of my old Lego. I'd gear the DC motor to the propeller shaft using some of those parts. This is starting to sound like a good challenge - I just might give it a try...
     
    Last edited: Sep 14, 2007
  13. ThermalRunaway

    ThermalRunaway New Member

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    I'll disagree with you very slightly there Hank. I used a PC fan as part of a crude laser projector project. I cut it away from the assembly and removed the blades, but used the base of the fan to mount the rotating laser - and it worked a treat!

    I can see where you're coming from though, a PC fan probably doesn't generate enough power to give useful thrust, especially if you start trying to lift any kind of weight with it.

    Brian
     
  14. Hank Fletcher

    Hank Fletcher New Member

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    Okay, I'll give you that. I guess I was over-generalizing. Other than cooling, there might be a number of applications that a PC fan motor might be useful for spinning things, but not so much for thrust.
     
  15. 3v0

    3v0 Coop Build Coordinator Forum Supporter

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    A fan is most possibly a dead end but CD motors are not.

    google for "park flyer CD motor rewind"
     
  16. Krumlink

    Krumlink New Member

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    Ok i have been thinking of a design :)
    I made it in Paint :D
     

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