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Maximum power output for a human for short periods?

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01 / Original postMaximum power output for a human for short periods?Robert Clark · 15 Nov 2007 02 / This pagePosts 1–6Page 1 of 1 · chronological order 03 / Latest replyPost #6monk · 6 Dec 2007

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Triathlon
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15 November 2007
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Robert Clark
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  1. Original post
    Robert Clark
    Archived post
    #1

    I'm interested in producing human powered vehicles. I copied below a
    proposed method for generating 1800 watts of human generated power for
    a period of say 1 minute. Some references suggest you might only be
    able to get up to say 1,000 watts for over a minute. They say
    cyclists might be able to get up to 2,000 watts but only for short
    bursts. But I need this over a minute or so for my purposes.
    Have their been weightlifting instances where the lifter uses both
    the upper and lower body and is able to get high reps at a total
    lifted weight of over 3 times their body weight?
    Also, I might need the power generation to be continuous in both the
    positive and negative directions. Then could a lifter pull back with
    as much force when reversing a leg press as when he extended his legs?
    And could he pull back with his arms when reversing a bench press with
    as much force as when he extended his arms?

    Bob Clark

    =============================================================
    Newsgroups: sci.astro, sci.physics, sci.space.policy, sci.engr.mech
    From: Robert Clark <[email hidden]>
    Date: Tue, 13 Nov 2007 13:42:05 -0800
    Local: Tues, Nov 13 2007 4:42 pm
    Subject: Re: Proposal for hovering flight.

    On Nov 11, 2:36 pm, "CWatters" <[email hidden]>

    Quoted message said:

    news:[email hidden]...

    Quoted message said:

    It's interesting to take a look at how man powered flight has been
    achieved - bear in mind that racing cyclists can only put out about a third
    of a horsepower continuously...

    Quoted message said:

    http://en.wikipedia.org/wiki/Man-powered_flight

    Quoted message said:

    I believe the prize for a man powered helicopter is still unclaimed although
    some have managed to get off the ground on less than one horsepower!>http://www.humanpoweredhelicopters.org

    ....
    Thanks for those links on human powered flight. I found this link
    that suggested top cyclists could generate 500 watts continuously and
    900 watts peak (though perhaps with some chemical augmentation ;-) )

    Olympic Human Powered Flight
    Human Powered Flight Undergoes Renaissance With Olympic Competition.
    "//humans can produce about 100 watts continuously, with peaks of 400
    watts or more// That may be so on average, but for a trained cyclist
    those stats are quite low. I'm at 300 watts continuous / over 900
    peak
    with moderate training. Lance Armstrong somehow manages 500
    continuous. It's probably safe to say Olympic cyclists can maintain
    at
    least 400 watts."
    http://www.halfbakery.com/idea/Olympic_20Human_20Powered_20Flight

    The prize discussed on the human powered helicopters site only
    requires that the craft hover at 3 meters under human power only for
    one minute.
    A fit male probably could do leg presses of twice his body weight
    for
    several reps and bench presses of his weight for several reps. These
    would only have to be done for 60 seconds.
    To see these are reasonable capabilities note that in climbing
    stairs
    we're actually supporting our weight most of the time on one leg.
    We're using both legs only for the short time when we're switching
    from one leg to the other. So just climbing stairs we're doing the
    equivalent of supporting twice our body weight. A normal fit person
    climbing stairs certainly could go up one stair in one second, with
    the stairs being about 8 inches, 20 centimeters high. Then a good
    athlete could do the equivalent of 100 centimeters, one meter, per
    second up the stairs if only for one minute.
    For the bench press, a normal fit male could do several reps of
    push-
    ups, which is supporting your weight with your arm and chest muscles,
    once each second. The distance would be about 2 feet. Then a good
    athlete should be able to raise his weight in a bench press 1 meter
    once per second for several reps for a minute.
    Note for both of these I'm assuming that both the positive and
    negative directions count as a single repetition, not a full cycle,
    as
    in normal exercising. This corresponds to how this would be useful
    for our scenario since both the positive and negative directions
    could
    be used for driving the craft.
    However, there is a question of whether both the upper and lower
    body
    could be used at this intensity at the same time. I think for the top
    athletes this could be possible at least for one minute. Then we may
    suppose a top athlete raising and lowering 3 times his weight 1 meter
    once per second, that is, a full up-down cycle taking 2 seconds, for
    60 seconds.
    For a small 60 kg athlete, this would be 180 kg raised 1 meter per
    second or 1800 N over 1 m per second, or 1800 watts. For the weight
    of the person of 60 kg, this is a weight to power ratio of 33 to 1. I
    will assume that the canopies and the shell holding the craft can be
    made quite light, and will take simply the total weight to be 60 kg.
    Remember now that the weight to power ratio is 100/v. So v is 3 m/s,
    for the speed at which the canopies are brought down. Then plug this
    into the equation for the drag produced to see how large the canopy
    has to be raised 60 kg. We need to produce 600 N of force. This
    requires a canopy diameter of about 6.6 meters.

    Bob Clark
    ==============================================================

    Report
  2. Robert Clark
    Archived post
    #2

    On Nov 16, 12:25 am, Paul Cassel <[email hidden]>

    Quoted message said:
    Robert Clark said:

    I'm interested in producinghuman poweredvehicles. I copied below a
    proposed method for generating 1800wattsof human generated power for
    a period of say 1 minute. Some references suggest you might only be
    able to get up to say 1,000wattsfor over a minute. They say
    cyclists might be able to get up to 2,000wattsbut only for short
    bursts. But I need this over a minute or so for my purposes.
    Have their been weightlifting instances where the lifter uses both
    the upper and lower body and is able to get high reps at a total
    lifted weight of over 3 times their body weight?
    Also, I might need the power generation to be continuous in both the
    positive and negative directions. Then could a lifter pull back with
    as much force when reversing a leg press as when he extended his legs?
    And could he pull back with his arms when reversing a bench press with
    as much force as when he extended his arms?

    I doubt a human can produce a kw for even very short periods and surely
    not a minute much less 1.8kw. What you can try is to have your human
    operating at a lower output for a time but store some of that energy in,
    say, a flywheel and then harness the flywheel's kinetic energy when you
    need 1 minute of 1.8 kw.

    Try asking at a bicycle group such as rec.bicycles.tech. Many of the
    guys there are quite familiar with human energy output capacities. A
    typical civilian thinks he's working hard at 150watts.

    -paul

    Producing 1800 watts for a few seconds should be within the range of
    the best power lifters and perhaps for up to a minute. Remember 1 watt
    means applying a force of 1 newton through a distance of 1 meter in 1
    second. So if you lifted 1 kg, that's 9.8 newtons of force, about 10
    newtons, for 1 meter in 1 second, that would be 10 watts. So lifting
    180 kg, 1 meter high in 1 second would be 1800 watts.
    The best power lifters can do squats of several times their body
    weight for 1 rep. Let's say the power lifter weighed 100 kg, about 220
    lbs. He might be able to do 3 times his weight for a single rep. That
    would be 300 kg. But remember he's actually raising his own weight as
    well. So he's actually lifting 4 times his weight, 400 kg for this one
    rep. For a male of average height, he might be raising this over a
    distance of 1 meter.
    So doing 1800 watts of power for one minute would be like giving this
    power lifter a weight of only 60 kg (for a total weight of 180 kg) and
    doing squats with this light weight for the high number of reps of 1
    per second over one minute. I think this would be possible for a
    weight so much lighter than their usual 1 rep maximum weight.

    Bob Clark

    Report
  3. sycochkn
    Archived post
    #3

    "Paul Cassel" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:
    Robert Clark said:

    I'm interested in producing human powered vehicles. I copied below a
    proposed method for generating 1800 watts of human generated power for
    a period of say 1 minute. Some references suggest you might only be
    able to get up to say 1,000 watts for over a minute. They say
    cyclists might be able to get up to 2,000 watts but only for short
    bursts. But I need this over a minute or so for my purposes.
    Have their been weightlifting instances where the lifter uses both
    the upper and lower body and is able to get high reps at a total
    lifted weight of over 3 times their body weight?
    Also, I might need the power generation to be continuous in both the
    positive and negative directions. Then could a lifter pull back with
    as much force when reversing a leg press as when he extended his legs?
    And could he pull back with his arms when reversing a bench press with
    as much force as when he extended his arms?


    I doubt a human can produce a kw for even very short periods and surely
    not a minute much less 1.8kw. What you can try is to have your human
    operating at a lower output for a time but store some of that energy in,
    say, a flywheel and then harness the flywheel's kinetic energy when you
    need 1 minute of 1.8 kw.

    Try asking at a bicycle group such as rec.bicycles.tech. Many of the guys
    there are quite familiar with human energy output capacities. A typical
    civilian thinks he's working hard at 150 watts.

    -paul

    A human is good for about 1 hp for 12 seconds. Max continous is probably
    around 1/2 hp.

    Bob

    Report
  4. Paul Cassel
    Archived post
    #4
    Robert Clark said:

    I'm interested in producing human powered vehicles. I copied below a
    proposed method for generating 1800 watts of human generated power for
    a period of say 1 minute. Some references suggest you might only be
    able to get up to say 1,000 watts for over a minute. They say
    cyclists might be able to get up to 2,000 watts but only for short
    bursts. But I need this over a minute or so for my purposes.
    Have their been weightlifting instances where the lifter uses both
    the upper and lower body and is able to get high reps at a total
    lifted weight of over 3 times their body weight?
    Also, I might need the power generation to be continuous in both the
    positive and negative directions. Then could a lifter pull back with
    as much force when reversing a leg press as when he extended his legs?
    And could he pull back with his arms when reversing a bench press with
    as much force as when he extended his arms?


    I doubt a human can produce a kw for even very short periods and surely
    not a minute much less 1.8kw. What you can try is to have your human
    operating at a lower output for a time but store some of that energy in,
    say, a flywheel and then harness the flywheel's kinetic energy when you
    need 1 minute of 1.8 kw.

    Try asking at a bicycle group such as rec.bicycles.tech. Many of the
    guys there are quite familiar with human energy output capacities. A
    typical civilian thinks he's working hard at 150 watts.

    -paul

    Report
  5. Email address hidden
    Archived post
    #5
    Robert Clark said:

    On Nov 16, 12:25 am, Paul Cassel <[email hidden]>

    Quoted message said:
    Robert Clark said:

    I'm interested in producinghuman poweredvehicles. I copied below a
    proposed method for generating 1800wattsof human generated power for
    a period of say 1 minute. Some references suggest you might only be
    able to get up to say 1,000wattsfor over a minute. They say
    cyclists might be able to get up to 2,000wattsbut only for short
    bursts. But I need this over a minute or so for my purposes.
    Have their been weightlifting instances where the lifter uses both
    the upper and lower body and is able to get high reps at a total
    lifted weight of over 3 times their body weight?
    Also, I might need the power generation to be continuous in both the
    positive and negative directions. Then could a lifter pull back with
    as much force when reversing a leg press as when he extended his legs?
    And could he pull back with his arms when reversing a bench press with
    as much force as when he extended his arms?

    Quoted message said:

    I doubt a human can produce a kw for even very short periods and surely
    not a minute much less 1.8kw. What you can try is to have your human
    operating at a lower output for a time but store some of that energy in,
    say, a flywheel and then harness the flywheel's kinetic energy when you
    need 1 minute of 1.8 kw.

    Quoted message said:

    Try asking at a bicycle group such as rec.bicycles.tech. Many of the
    guys there are quite familiar with human energy output capacities. A
    typical civilian thinks he's working hard at 150watts.

    Quoted message said:

    -paul

    Producing 1800 watts for a few seconds should be within the range of
    the best power lifters and perhaps for up to a minute. Remember 1 watt
    means applying a force of 1 newton through a distance of 1 meter in 1
    second. So if you lifted 1 kg, that's 9.8 newtons of force, about 10
    newtons, for 1 meter in 1 second, that would be 10 watts. So lifting
    180 kg, 1 meter high in 1 second would be 1800 watts.
    The best power lifters can do squats of several times their body
    weight for 1 rep. Let's say the power lifter weighed 100 kg, about 220
    lbs. He might be able to do 3 times his weight for a single rep. That
    would be 300 kg. But remember he's actually raising his own weight as
    well. So he's actually lifting 4 times his weight, 400 kg for this one
    rep. For a male of average height, he might be raising this over a
    distance of 1 meter.
    So doing 1800 watts of power for one minute would be like giving this
    power lifter a weight of only 60 kg (for a total weight of 180 kg) and
    doing squats with this light weight for the high number of reps of 1
    per second over one minute. I think this would be possible for a
    weight so much lighter than their usual 1 rep maximum weight.

    Bob Clark

    The information you want is mostly here: http://www.velocitynation.com/article.aspx?ID=108&CID=56
    Besides power, weight, or rather lack of it, is important if you are
    considering flight.
    "Marty Nothstien weighted 220 pounds or 100 kilos in the 1996
    Olympics, it takes a lot of power to get that much weight up to 45+
    MPH but with maximum power at over 2200 watts at peak his engine was
    more than big enough. That's well above great road sprinters who are
    comparatively small like Cipollini (1900 watt max) or Pettachi
    (reported 1700 watts). Conversely Chris Boardman was able to produce
    over 440 watts for an hour to break the hour record but his top power
    in a sprint was only 1000 watts, not enough to win a cat 5 sprint at
    Floyd Bennett Field. "

    Report
  6. monk
    Archived post
    #6

    On Wed, 14 Nov 2007 16:17:41 -0800, Robert Clark

    Quoted message said:


    Quoted message said:

    I believe the prize for a man powered helicopter is still unclaimed although
    some have managed to get off the ground on less than one horsepower!>http://www.humanpoweredhelicopters.org

    Quoted message said:


    The prize discussed on the human powered helicopters site only
    requires that the craft hover at 3 meters under human power only for
    one minute.

    Don't forget that you have to get up to 3 meters first then stay there
    for a minute. Also getting up to that height will require considerably
    more energy than hovering there.

    Report

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