Re: Horsepower

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Re: Horsepower

Geopilot
Thanks.
So I can hang a pound weight off some of these motor axels off a roof
and see how fast it can raise it by winding the string around the axle
to get an idea of the power of the toy motors.

On Sun, 23 Dec 2007 9:07 pm, Ronald Anderson wrote:

> Dear Sir,
>
> The subject you need to look up is dynamometer. This is a device that
> measure rotational power. 1 hp = 550 ft/lb/sec is the definition or 1
> hp = 33000 ft/lbs/min
>
> HP is essentially the amount of work done within a period of time. The
> same work done in ever shorter amounts of time equals ever greater HP
> being expressed in that short period of time.
>
> When HP is measured via rotation the calculation is  HP = (RPM x Tq )/
> 5252
>
> Tq is Torque in lbs./foot or said literally the number of lbs force at
> one foot from center rotation.
>
> Thus to measure hp you need to be able to measure force (Torque) and
> RPM to calculate HP. 
>
> Sincerely,
>
> Ron Anderson
>
> Black Sheep Technology
>
> www.bsio.us [http://www.bsio.us]
>
> www.black-sheep.us [http://www.black-sheep.us]
>
> --------------------
>
> Looking for last minute shopping deals? Find them fast with Yahoo!
> Search.
> [http://us.rd.yahoo.com/evt=51734/*http://tools.search.yahoo.com/newsearch/category.php?category=shopping]


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Re: Horsepower

Geopilot
Thanks.
So I can hang a pound weight off some of these motor axels off a roof
and see how fast it can raise it by winding the string around the axle
to get an idea of the power of the toy motors.

On Sun, 23 Dec 2007 9:07 pm, Ronald Anderson wrote:

> Dear Sir,
>
> The subject you need to look up is dynamometer. This is a device that
> measure rotational power. 1 hp = 550 ft/lb/sec is the definition or 1
> hp = 33000 ft/lbs/min
>
> HP is essentially the amount of work done within a period of time. The
> same work done in ever shorter amounts of time equals ever greater HP
> being expressed in that short period of time.
>
> When HP is measured via rotation the calculation is  HP = (RPM x Tq )/
> 5252
>
> Tq is Torque in lbs./foot or said literally the number of lbs force at
> one foot from center rotation.
>
> Thus to measure hp you need to be able to measure force (Torque) and
> RPM to calculate HP. 
>
> Sincerely,
>
> Ron Anderson
>
> Black Sheep Technology
>
> www.bsio.us [http://www.bsio.us]
>
> www.black-sheep.us [http://www.black-sheep.us]
>
> --------------------
>
> Looking for last minute shopping deals? Find them fast with Yahoo!
> Search.
> [http://us.rd.yahoo.com/evt=51734/*http://tools.search.yahoo.com/newsearch/category.php?category=shopping]



www.GlobalBoiling.com for daily images about hurricanes, globalwarming
and the melting poles.

www.ElectricQuakes.com daily solar and earthquake images.

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Re: Horsepower

Morgan LaMoore
In reply to this post by Geopilot
On Dec 24, 2007 1:26 AM, GWMobile <[hidden email]> wrote:
> Thanks.
> So I can hang a pound weight off some of these motor axels off a roof
> and see how fast it can raise it by winding the string around the axle
> to get an idea of the power of the toy motors.

Yeah; here's a formula for you:

HP=0.00182*W*h/t

where w is the weight you're lifting (in pounds)
h is the height you're lifting it (in feet)
t is the time it takes to lift (in seconds)

The factor 0.00182 converts from ft-pounds/s to HP.

Note that this formula assumes it's traveling at constant velocity, so
you should start the measurement about half-way up. Also, note that
the factor of 0.0018 means that you'll need a pretty big weight to
measure decent motors.

Also, because most motors are better at higher RPMs, you'll probably
need to use some gearing or a very small radius so the motor puts out
low torque at high RPMs.

Finally, watch out for safety. If your motor is too powerful for the
weights you use, it could send them flying. (I've done this before,
but only with a relatively weak motor and 2.5 lb weights. Also, I
wasn't trying to measure the power; I was trying to control torque.)

You'll get much better results with a dynamometer, but for a home
experiment, a weight test is much easier.

-Morgan LaMoore

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Re: Horsepower

Jeff Shanab
In reply to this post by Geopilot
And use a wide spool witha couter bearing so the string winding diameter
doesn't change too much. :-)

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