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Re: [PSUBS-MAILIST] Horsepower
Actually companys are now not puling that stunt. that was the norm in the 50-70's
*********** REPLY SEPARATOR ***********
On 1/27/00, at 7:38 PM, Marsee Skidmore wrote:
>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
>> >>>
>> >>
>> >>
>> >>
>>