[Date Prev][Date Next]
[Chronological]
[Thread]
[Top]
Re: [PSUBS-MAILIST] Horsepower
One other goofy detail about ratings. Internal combustion engines are rated
on a dynamometer with almost none of the parasitic loads. None of those
pesky accessories like a water pump, fuel pump or radiator fan. - Joe
----- Original Message -----
From: Greg Teiber <wolfe19@megsinet.net>
To: <personal_submersibles@psubs.org>
Sent: Thursday, January 27, 2000 12:53 AM
Subject: Re: [PSUBS-MAILIST] Horsepower
> electric motor's have maximum torque at 0rpm. GAs motors have maximum
torque somewhere pretty high, anywhere from 1000rpm in the Jag XJ motors, to
7000rpm in the honda S2000 :) problem is, Horesepower IS Horsepower. a
60hp motor will do more work than a 20hp one. NO MATTER WHAT. That 20hp is
driveable because it has such huge torque. Plain and simple. Drivers like
torque. Then again, so do propellers. And what are we trying to turn :)
Electric motors are ideal for out situation.
>
> *********** REPLY SEPARATOR ***********
>
> On 1/27/00, at 12:26 AM, D. Blake wrote:
>
> >Yeah, and that peaky power-curve is why internal combustion engines need
a
> >transmission and clutch. Both of which suck enormous amounts of
available
> >horsepower and energy through friction. The electric motor develops
torque
> >the instant you apply power, and maintains a more or less linear power
curve
> >throughout the RPM range. No need to rev the motor to obtain power, and
no
> >need to waste energy by idling.
> >Pull your front tires up against the curb. See if that 60hp internal
> >combustion engine will push you over the top without a few revs of the
motor
> >and dumping the clutch. Do the same with a 20hp series-wound DC motor
with
> >direct-drive to the rearend, and you will go immediatly over the top.
> >The stuff I have read says it's not uncommon to go zero to sixty and more
> >without ever having to shift gears. That is how linear the power-curve
is
> >with electric motors.
> >Big Dave
> >-----Original Message-----
> >From: Marsee Skidmore <heyred@email.msn.com>
> >To: personal_submersibles@psubs.org <personal_submersibles@psubs.org>
> >Date: Wednesday, January 26, 2000 11:28 PM
> >Subject: Re: [PSUBS-MAILIST] Horsepower
> >
> >
> >>The difference is in how the ratings are done. Electric motors have a
> >fairly
> >>linear power curve (hp vs. rpm), and are derated for continuous duty. In
> >>other words, the rated horsepower of an electric motor is on the low end
of
> >>the output curve, just to be conservative. Internal combustion engines
have
> >>a very peaky power curve, and are rated by the peak output.
Conservative,
> >>conshmervative, let's sell cars! Race car drivers like to run at the
peak
> >of
> >>the power curve, but those of us who pay for their own gas and overhauls
> >>operate a little bit further down on the curve. Three to one sounds
about
> >>right. A 60 hp Volkswagen runs just fine with a 20 hp electric motor. -
Joe
> >>----- Original Message -----
> >>From: <SeaLordOne@aol.com>
> >>To: <personal_submersibles@psubs.org>
> >>Sent: Wednesday, January 26, 2000 5:59 PM
> >>Subject: [PSUBS-MAILIST] Horsepower
> >>
> >>
> >>> Teammates,
> >>>
> >>> Please help me with this one. According to an article in BOAT/U.S.
> >>Magazine
> >>> (January 2000, pages 24-25), electric motors somehow provide three
times
> >>the
> >>> performance of internal combustion engines. How can this be?
Horsepower
> >>is
> >>> horsepower is horsepower, isn't it?
> >>>
> >>> The article (Electric Boats Charging Back) is about coverting gasoline
or
> >>> diesel boats into electric ones. The author (Ryck Lydecker) says: "He
> >>> calculates that to replace internal combustion engines, particularly
in
> >>> sailboats, the power ratio is about three-to-one. That is, a 3-hp
> >>electric
> >>> motor is adequate to replace a 9-hp outboard." I thought a 3-hp
diesel =
> >>a
> >>> 3-hp gasoline = a 3-hp electric = a 3-hp anything. Yes? No? Please
> >help
> >>me
> >>> out here. Does this guy know something I don't?
> >>>
> >>> Thanks,
> >>>
> >>> Doug
> >>>
> >>
> >>
> >>
>