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drones

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  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

#538069 — drones

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

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#538074

Dne 08/12/2015 v 22:29 RichD napsal(a):
> I notice, with these new toy drones, they all use quad 
> rotor design.  Why?
> 
> I never studied aerodynamics, but I'm willing to learn - 
> 

I would say the 1 or 3 of rotors
needs extra rotor to deal with the torsion,
and the 2 rotors in the opposite rotation
does not lead to good enough stability
and control.

4 rotors can deal well with both,
and is easy to manoeuvre to all directions
by the tilting of the whole platform.


-- 
Poutnik ( the Czech word for a wanderer )

Knowledge makes great men humble, but small men arrogant.

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#538079

Poutnik <poutnik4nntp@gmail.com> wrote:
> Dne 08/12/2015 v 22:29 RichD napsal(a):
>> I notice, with these new toy drones, they all use quad 
>> rotor design.  Why?
>> 
>> I never studied aerodynamics, but I'm willing to learn - 
>> 
> 
> I would say the 1 or 3 of rotors
> needs extra rotor to deal with the torsion,
> and the 2 rotors in the opposite rotation
> does not lead to good enough stability
> and control.
> 
> 4 rotors can deal well with both,
> and is easy to manoeuvre to all directions
> by the tilting of the whole platform.

You can only tilt the whole platform by applying a force to it.

You can do that either by tilting the individual rotors, or by varying
power to the individual rotors, which is what is usually done.

You have to have power control, so that is 4 servos.

If you want to tilt the rotors, that is 2 servos per rotor for a total
of 8 more servos.

 

-- 
Jim Pennino

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#538075

On Tuesday, December 8, 2015 at 4:29:51 PM UTC-5, RichD 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

From an engineering perspective, an equilateral triangular design
would be lighter, cheaper, and just as functional as the quad
design. So why quad rather than 3?

If one rotor fails out of the available four, there's minimal chance
of recovery. Possibly none. Albeit possible, it's highly unlikely
given a weight load of one's favorite peeping tom, steerable HDTV
realtime connected to youTube, camera. What else are they carrying?!
C'mon. Did you see that bathing naked teen blonde beauty over there?!
So, basically, no real advantage over the triangular design.

So put on your business and climate change polluting hat(s). Four
rotors are more weight, mass, and cost more money. More money, more
profit. More profit, less hunger, housing, and lots more women. TMI?

Fwiw, I worked in a Conceptual Design Group (CDG) of future aerospace
technologies as a GN&CS (==ACS) engineer. Once. If you can't do the
acronyms, stay away from all kinds of NASA. Their MACHO, their
WIMPS. Take my advice with a grain of YMMV salt Salt SALT.

-- Mahipal "IPMM... NASA NSA QED iSTFU DREAM PRESS ON on On..."

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#538077

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.


-- 
Jim Pennino

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#538089

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!

"Professor" Sam Wormley will now explain the physics of why this is true.

Math "explains" everything in the universe!


-- 

       ___           ___           ___            ___
      /\  \         /\  \         /\__\          /\  \
     /::\  \       /::\  \       /::|  |         \:\  \
    /:/\:\  \     /:/\:\  \     /:|:|  |     ___ /::\__\
   /::\~\:\__\   /::\~\:\  \   /:/|:|  |__  /\  /:/\/__/
  /:/\:\ \:|__| /:/\:\ \:\__\ /:/ |:| /\__\ \:\/:/  /
  \:\~\:\/:/  / \:\~\:\ \/__/ \/__|:|/:/  /  \::/  /
   \:\ \::/  /   \:\ \:\__\       |:/:/  /    \/__/
    \:\/:/  /     \:\ \/__/       |::/  /
     \::/__/       \:\__\         /:/  /
      ~~            \/__/         \/__/

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#538103

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.

Two rotors in tandem solve the torque problem but get mechanically complex.

Two rotors in line also solve the torque problem but this also gets
mechanically complex needing full tilt control for both rotors.

Three rotors require trigonometric calculations for rotor control.

Four rotors is simplest of all, only reqiring rotor power control.

Anything above four starts complicating calculations for rotor control.

> "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!
 
 

-- 
Jim Pennino

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#538147

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! :-)

> 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.

> Two rotors in line also solve the torque problem but this also gets
> mechanically complex needing full tilt control for both rotors.

Yes.

> 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.

> 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!

> Anything above four starts complicating calculations for rotor
> control.

I think the $20 controller does up to 8 rotors.

>> "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!
>
>
>


-- 

       ___           ___           ___            ___
      /\  \         /\  \         /\__\          /\  \
     /::\  \       /::\  \       /::|  |         \:\  \
    /:/\:\  \     /:/\:\  \     /:|:|  |     ___ /::\__\
   /::\~\:\__\   /::\~\:\  \   /:/|:|  |__  /\  /:/\/__/
  /:/\:\ \:|__| /:/\:\ \:\__\ /:/ |:| /\__\ \:\/:/  /
  \:\~\:\/:/  / \:\~\:\ \/__/ \/__|:|/:/  /  \::/  /
   \:\ \::/  /   \:\ \:\__\       |:/:/  /    \/__/
    \:\/:/  /     \:\ \/__/       |::/  /
     \::/__/       \:\__\         /:/  /
      ~~            \/__/         \/__/

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#538165

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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#538137

On 12/8/15 3:29 PM, RichD wrote:
> I notice, with these new toy drones, they all use quad
> rotor design.  Why?


   Review | Quadcopter
> https://en.wikipedia.org/wiki/Quadcopter

> Quadcopters generally use two pairs of identical fixed pitched
> propellers; two clockwise (CW) and two counter-clockwise (CCW). These
> use independent variation of the speed of each rotor to achieve
> control. By changing the speed of each rotor it is possible to
> specifically generate a desired total thrust; to locate for the
> centre of thrust both laterally and longitudinally; and to create a
> desired total torque, or turning force.

> https://en.wikipedia.org/wiki/Quadcopter#Flight_dynamics

> Each rotor produces both a thrust and torque about its center of
> rotation, as well as a drag force opposite to the vehicle's direction
> of flight. If all rotors are spinning at the same angular velocity,
> with rotors one and three rotating clockwise and rotors two and four
> counterclockwise, the net aerodynamic torque, and hence the angular
> acceleration about the yaw axis, is exactly zero, which implies that
> the yaw stabilizing rotor of conventional helicopters is not needed.
> Yaw is induced by mismatching the balance in aerodynamic torques
> (i.e., by offsetting the cumulative thrust commands between the
> counter-rotating blade pairs).




-- 

sci.physics is an unmoderated newsgroup dedicated
to the discussion of physics, news from the physics
community, and physics-related social issues.

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#538150

On 12/08/2015 10:44 PM, Sam Wormley wrote:
> On 12/8/15 3:29 PM, RichD wrote:
>> I notice, with these new toy drones, they all use quad
>> rotor design.  Why?
>
>
>    Review | Quadcopter
>> https://en.wikipedia.org/wiki/Quadcopter
>
>> Quadcopters generally use two pairs of identical fixed pitched
>> propellers; two clockwise (CW) and two counter-clockwise (CCW). These
>> use independent variation of the speed of each rotor to achieve
>> control. By changing the speed of each rotor it is possible to
>> specifically generate a desired total thrust; to locate for the
>> centre of thrust both laterally and longitudinally; and to create a
>> desired total torque, or turning force.
>
>> https://en.wikipedia.org/wiki/Quadcopter#Flight_dynamics
>
>> Each rotor produces both a thrust and torque about its center of
>> rotation, as well as a drag force opposite to the vehicle's direction
>> of flight. If all rotors are spinning at the same angular velocity,
>> with rotors one and three rotating clockwise and rotors two and four
>> counterclockwise, the net aerodynamic torque, and hence the angular
>> acceleration about the yaw axis, is exactly zero, which implies that
>> the yaw stabilizing rotor of conventional helicopters is not needed.
>> Yaw is induced by mismatching the balance in aerodynamic torques
>> (i.e., by offsetting the cumulative thrust commands between the
>> counter-rotating blade pairs).

You know Sam, this group is for discussion not cut and paste from 
wilkipedia. Say, did you send them your donation yet? Propaganda and 
censorship takes money, you know!

It is interesting the way a quad or even better an octocopter can be 
made to rotate and steer in the plane normal to it's central axis (yaw) 
while maintaining constant lift simply through motor controls.

I've decided I need a drone to look at my roof in the spring to see if 
any tiles have been pulled out by the ice. I've been using binoculars to 
do that, but a drone would be so much cooler.



-- 

       ___           ___           ___            ___
      /\  \         /\  \         /\__\          /\  \
     /::\  \       /::\  \       /::|  |         \:\  \
    /:/\:\  \     /:/\:\  \     /:|:|  |     ___ /::\__\
   /::\~\:\__\   /::\~\:\  \   /:/|:|  |__  /\  /:/\/__/
  /:/\:\ \:|__| /:/\:\ \:\__\ /:/ |:| /\__\ \:\/:/  /
  \:\~\:\/:/  / \:\~\:\ \/__/ \/__|:|/:/  /  \::/  /
   \:\ \::/  /   \:\ \:\__\       |:/:/  /    \/__/
    \:\/:/  /     \:\ \/__/       |::/  /
     \::/__/       \:\__\         /:/  /
      ~~            \/__/         \/__/

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