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Re: drones

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benj <none@gmail.com> wrote:
> On 12/08/2015 06:48 PM, jimp@specsol.spam.sux.com wrote:
>> benj <none@gmail.com> wrote:
>>> On 12/08/2015 05:02 PM, jimp@specsol.spam.sux.com wrote:
>>>> RichD <r_delaney2001@yahoo.com> wrote:
>>>>> I notice, with these new toy drones, they all use quad rotor
>>>>> design.  Why?
>>>>>
>>>>> I never studied aerodynamics, but I'm willing to learn -
>>>>>
>>>>> -- Rich
>>>>
>>>> Getting stability is simpler, i.e. it doesn't require
>>>> trigometric calculations that 3 rotors would.
>>>>
>>>
>>> It's simple math called a "series". One rotor doesn't work. two is
>>> better, three is better still, four is even better and eight is
>>> best of all!
>>
>> One rotor works; you just need power and tilt control for the rotor
>> and something like  a tail rotor to counter main rotor torque.
> 
> Um, have you been taking lessons from Glazier again?  In my math book a 
> lifting rotor and a tail rotor adds up to... er... wait for it... two 
> rotors! :-)

Note "something like  a tail rotor".

 
>> Two rotors in tandem solve the torque problem but get mechanically
>> complex.
> 
> Yeah, a friend of mine has a toy copter with counter rotating (two) 
> rotors. Works. But as far as I can tell you have to be 6 years old or 
> younger to actually fly it without crashing.

Apparently it takes a death wish to fly a real one; note that such
fell out of favor long ago.
 
>> Two rotors in line also solve the torque problem but this also gets
>> mechanically complex needing full tilt control for both rotors.
> 
> Yes.

But in a real one gives one a great view of the world passing by
look over the ramp of a CH-47.


>> Three rotors require trigonometric calculations for rotor control.
> 
> Um, have you noticed that 32 bit computers the size of postage stamps 
> are available for a couple of bucks these days. Even scarier is they all 
> seem to come from China. For about $20 you can get a control for any 
> number of rotors. All math done for you. You've been working with the 
> military pricing schedule for too long.

The business is cutthroat; the cheapest implementation wins. Summing
analog error signals is cheaper than A/D, math, D/A.

>> Four rotors is simplest of all, only reqiring rotor power control.
> 
> Yeah, my friend has one of those too! Doesn't have the GPS or barometric 
> stabilizer, but while easier than the two rotor job to fly it still 
> takes a bit of skill!

Trivial to stabilize with cheap gyros.

>> Anything above four starts complicating calculations for rotor
>> control.
> 
> I think the $20 controller does up to 8 rotors.

Again, the market is cutthroat; need to have something beyond just
8 rotors for marketing.

>>> "Professor" Sam Wormley will now explain the physics of why this is
>>> true.
>>
>> A paper airplane designed by the above would likely explode...
>>
>>> Math "explains" everything in the universe!

Been playing with the idea of building one, but with fossil fuel
motors for range and endurance, thought I prefer things with wings.


-- 
Jim Pennino

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Thread

drones RichD <r_delaney2001@yahoo.com> - 2015-12-08 13:29 -0800
  Re: drones Poutnik <poutnik4nntp@gmail.com> - 2015-12-08 22:56 +0100
    Re: drones jimp@specsol.spam.sux.com - 2015-12-08 22:16 +0000
  Re: drones Mahipal <mahipal7638@gmail.com> - 2015-12-08 14:02 -0800
  Re: drones jimp@specsol.spam.sux.com - 2015-12-08 22:02 +0000
    Re: drones benj <none@gmail.com> - 2015-12-08 17:49 -0500
      Re: drones jimp@specsol.spam.sux.com - 2015-12-08 23:48 +0000
        Re: drones benj <none@gmail.com> - 2015-12-08 23:08 -0500
          Re: drones jimp@specsol.spam.sux.com - 2015-12-09 06:16 +0000
  Re: drones Sam Wormley <swormley1@gmail.com> - 2015-12-08 21:44 -0600
    Re: drones benj <none@gmail.com> - 2015-12-08 23:22 -0500

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