Ah, right. I see what Captain Kittredge and Michael are talking about.
The rating given to a combustion engine is it's maximum peak horse
power (it's a marketing thing to sell more cars). When using a car,
you don't get peak power all the time, just for short bursts, most
of the time you're using a 1/2 to 1/3 of the power. Also, you can't
go above this rating without modifying the engine (adding turbo
chargers, and other engine mods).
The rating given to electric motors is normally it's continous
duty power output - i.e. what it should be used for most of the
time. But, the electric motor is capable of a lot more peak
power output, say around x2 to x3 (depends on the motor, some
are less than x2) for short periods of time.
I read this on a website for converting cars to electric.
Ian.
On Fri, 23 Sep 2005 08:41:02 -0400
"Dan H."wrote:
> Why you'll find a difference when using electric rather then internal
> combustion is; with internal combustion you get your peek power at the top
> of it's, rather pointy, power curve, near it's highest RPMs. Electric
> motors, have a more constant power curve until they are really bogged down.
> Even then, they don't stop trying or stall. That is, they just keep trying
> harder, until they blow a fuse or fry themselves. An electric motors can
> take a short burst of exceeding it's rating but only until the added heat it
> generates destroys it.
>
> Some motors are rated for constant duty and some are rated with duty cycles.
>
> You can't get something for nothing. Brian is correct.
> > Horsepower is the same no matter what source it is coming from.
> >
> > 1 HP = 746 watts
> This is in a perfect world. In reality, you don't get all 1 HP of power to
> use, since each way of converting the 746 watts of energy to motion has it's
> inefficiencies, causing a power loss.
>
> Dan H.
>
> ----- Original Message -----
> From: "Brian Cox"
> To:
> Sent: Friday, September 23, 2005 12:35 AM
> Subject: Re: [PSUBS-MAILIST] Hp vs hp
>
>
> > Horsepower is the same no matter what source it is coming from.
> >
> > 1 HP = 746 watts
> >
> > Brian
> > ----- Original Message -----
> > From: "Michael Holt"
> > To: "Personal Submersibles List"
> > Sent: Thursday, September 22, 2005 8:07 PM
> > Subject: [PSUBS-MAILIST] Hp vs hp
> >
> >
> >> Did we ever resolve the question about the difference between horsepower
> >> produced by
> >> steam engines, etc., and horsepower produced by electric motors? On
> >> Captain Kittredge's
> >> video, I recall that he said that HP for electric was twice (or half?)
> >> the output of HP from
> >> any other source.
> >>
> >> What triggered this question was the Amfibidiver site. It had a link to
> >> a hovercraft site.
> >> Thesmallest hovercraft is supposed to have either a 3-7 HP gasoline
> >> engine or a 1-2 HP
> >> electric motor.
> >>
> >>
> >>
> >> Mike
> >>
> >>
> >>
> >>
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