Full Frontal

Discussion in 'Recumbent bicycles' started by Erich Hartman, Jun 27, 2003.

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  1. Rolf and I were in the photo studio shooting pictures for the Volae manual and discussing a thread
    I'd read on this message board about recumbent frontal area in relation to DF bikes. (Cutting out
    all the discussion to keep the story short) we eventually ended up taking a series of shots of him
    on a Volae and in various positions on a nice upright racing bike. We've been circulating this photo
    around the Hostel Shoppe for a while, but we've had such a reaction from everyone we've shared it
    with, that I thought it might be time to show it to the rest of the world. While it's definately not
    a technically perfect study, it is a pretty visually-compelling illustration of the incredible
    frontal area advantage that performance recumbents enjoy over performance uprights.

    http://www.hostelshoppe.com/images/tech/df_vs_volae.jpg

    NOTE: While this wasn't intended to be public and is by no means a scientific study, we were careful
    to leave the camera and bikes in the same relative position throughout the photos. I cleaned
    up the images (removed the trainer and background) and merged them into one. Also, note that
    he doesn't actually have aero bars in the last DF photo - we simulated the position by having
    him rest his forearms on the handlebars.

    Have Fun,

    Erich Hartman http://www.hostelshoppe.com
     
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  2. Tony

    Tony Guest

    Now that's cool, Eric. Thanks for the link!

    Regards,

    Tony
     
  3. I am disappointed I thought this was going to have tits in it. Oh well live and learn. "Tony"
    <[email protected]> wrote in message news:[email protected]...
    > Now that's cool, Eric. Thanks for the link!
    >
    > Regards,
    >
    >
    > Tony
     
  4. Tom Blum

    Tom Blum Guest

    Thank You!! Thank You!!

    Just the kind of data I've been looking for.

    Great job.

    Tom
     
  5. Nice photo work. This graphically shows what Vision's wind tunnel tests showed. (
    http://www.visionrecumbents.com/Images/WindTunnel.pdf ) A DF rider in an aero position has equal
    wind resistance to a Vision Sabre SWB recumbent. The recumbent rider looses some with legs spread
    and shoulders wide where the DF rider can tuck his elbows and shoulders and bring his legs
    in. Of course, the legs being full frontal on the DF brings things back to equal again. There are
    some losses on the bent with interrupted air currents between the legs and body also. The one
    advantage from an aerodynamic point on the bent is that it is easy to stay in that position,
    whereas on the DF, it becomes uncomfortable after a number of miles in that position. The
    advantage of a DF in hilly terrain, where there are long steep climbs, is that the rider can
    change positions to apply more efficient power and the aerodynamics are of no consequence at
    speeds below ~14mph.

    --
    Gene O _ \ _/\,%) (*)--(*)

    [email protected] http://home.att.net/~gene8

    "Erich Hartman" <[email protected]> wrote in message
    news:[email protected]...
    > Rolf and I were in the photo studio shooting pictures for the Volae manual and discussing a thread
    > I'd read on this message board about recumbent frontal area in relation to DF bikes. (Cutting out
    > all the discussion to keep the story short) we eventually ended up taking a series of shots of him
    > on a Volae and in various positions on a nice upright racing bike. We've been circulating this
    > photo around the Hostel Shoppe for a while, but we've had such a reaction from everyone we've
    > shared it with, that I thought it might be time to show it to the rest of the world. While it's
    > definately not a technically perfect study, it is a pretty visually-compelling illustration of the
    > incredible frontal area advantage that performance recumbents enjoy over performance uprights.
    >
    > http://www.hostelshoppe.com/images/tech/df_vs_volae.jpg
    >
    > NOTE: While this wasn't intended to be public and is by no means a scientific study, we were
    > careful to leave the camera and bikes in the same relative position throughout the photos. I
    > cleaned up the images (removed the trainer and background) and merged them into one. Also,
    > note that he doesn't actually have aero bars in the last DF photo - we simulated the
    > position by having him rest his forearms on the handlebars.
    >
    > Have Fun,
    >
    > Erich Hartman http://www.hostelshoppe.com
     
  6. Don

    Don Guest

    Interesting pictures. Thank you for posting them.

    One thing to note is that in the two DF pictures on the right the rider could not ride in that
    position for very long before they would hit a tree, parked car, or find a ditch. In other words
    they can not see where they are going. The pictures actually slightly exaggerate the DF aero benefit
    of aero bars or a low position. If riders raise their head to see, they lose some of the aero
    advantage shown in the picture. Also raising the head can be painful after a while. I know I can not
    ride in that position for very long. The recumbent style in the picture may actually have more aero
    advantage over the DFs than it appears.
     
  7. Seppo Sarlos

    Seppo Sarlos Guest

    Thanks for Erich Hartman to show the pictures
    http://www.hostelshoppe.com/images/tech/df_vs_volae.jpg

    I am trying to assemble my dream recumbent, which would have as small drag as possible without
    extensive fairing. In that purpose I was sitting on my prototype in front of a mirror and trying to
    outline correctly the cross sectional areas in different alternatives. A camera in my hand directed
    to the the mirror was intended to document the result.

    But after a while I started wondering why my shoes were so large compared to my head.

    I was positioned only about 2 metres from the mirror, and therefore everything nearer the mirror
    looked considerably larger than things farther away. I could not 'draw' the profile correctly e.g.
    to the surface of the mirror.

    You might notice the same effect by looking Erich's pictures, the width of the helmets of the two
    riders at the right. Quite different number of pixels. Tthe helmet of the rider nr 4 from the left
    (nr 2 from the right) is 57 pixels wide and the same helmet in the rider nr 5 from the left is 46
    pixels wide, the difference 11 pixels is 100*11/46 =24 percent.

    The effect of the camera distance can be minimized by going very far away from the rider and using a
    zoom lens.

    In practice the errors average out somewhat, but for serious developement work this effect should be
    considered. To strengthen our belief in the supremacy of recumbents vs DF these images work
    wonderfully. Mäy be too wonderfully.

    ?

    At first glance a human being looks at the face or head of the other human being. In the image the
    head of the DF rider looks huge and the head of the recumbent rider very tiny. :) We want to believe
    the cross sectional area of the recumbent bike and rider is tiny, so we are happy to see this :).
    The miracle is seen again. Our belief is stronger. Amen.

    Do not consider this as a deconstructive criticism of the work. I do not suspect the honesty of the
    authors, of course.There were adequate remarks of the effect in the posting. I am grateful for the
    steps they have done and the publication of the results, we are going to the same direction. I say
    this to emphasize how easy it is to see what one wants to see. Strengthen one's old beliefs. But to
    make scientific and technical progress we must be careful about hard facts all the time.

    Erich's images are actually very useful to provoke thoughts about recumbent developement.

    One sees that the recumbent rider could drastically diminish the cross sectional area of his (upper)
    body by being more horizontal. In my quick and dirty prototype (the web page will be there soon,
    perhaps within a week) I have the possibility to adjust the angle of the backrest during riding from
    almost vertical to fully horizontal (in vertical position the seat is low so that my feet can reach
    the ground, horizontal position is about 25 cm higher) . The effect of drag can be measured and also
    felt. When coasting downhill (without pedalling) the rider can keep the legs straight and together
    like a diver jumping legs first into water,just before hitting the water surface ('diving throught
    the air legs first'). The suit can be aerodynamic (think of the suits of ski jumpers, who fly at the
    speed of 100 km/h).

    The cross sectional area with legs straight might be half of the currently 'good' recumbent
    constructions without fairing , and thus the air resistance or air drag perhaps also half. Diving in
    the air without cumbersome fairing, perhaps with small wings, aerofoils here and there, all parts of
    bike and rider (!) made as aerodynamic as possible. Like waterdrops, like aeroplanes. Fly low. (wild
    idea: add some lift to minimize rolling resistance also if necessary?. Or vice versa). Birds,
    dolphins...

    But sigh, those legs. Any ideas to eliminate their drag or utilize it?

    In any case, pedals/shoes should be optimized like a water drop. If the speed is in the calm air
    e.g. 36 km/h (10 m/s) and pedalling rate 60 /min, the length of the pedal arm about 175 mm, then the
    air flow towards the shoes is about 9-11 m/s from the approximate front direction in all positions
    of the pedal.

    One could experiment with different aerodynamic forms in the handlebars (if they exist) , frame
    tubes, seat, pedals,helmets, legs,hands, etc eg. using some suitable foam. Ideas about materials?

    Any of these ideas can be freely used even commercially. I develope these as a hobby, as ' computer
    freeware' or 'careware' (careware? http://www.arachnoid.com/careware/index.html )

    "Erich Hartman" <[email protected]> kirjoitti viestissä
    news:[email protected]...
    > Rolf and I were in the photo studio shooting pictures for the Volae manual and discussing a thread
    > I'd read on this message board about recumbent frontal area in relation to DF bikes. (Cutting out
    > all the discussion to keep the story short) we eventually ended up taking a series of shots of him
    > on a Volae and in various positions on a nice upright racing bike. We've been circulating this
    > photo around the Hostel Shoppe for a while, but we've had such a reaction from everyone we've
    > shared it with, that I thought it might be time to show it to the rest of the world. While it's
    > definately not a technically perfect study, it is a pretty visually-compelling illustration of the
    > incredible frontal area advantage that performance recumbents enjoy over performance uprights.
    >
    > http://www.hostelshoppe.com/images/tech/df_vs_volae.jpg
    >
    > NOTE: While this wasn't intended to be public and is by no means a scientific study, we were
    > careful to leave the camera and bikes in the same relative position throughout the photos. I
    > cleaned up the images (removed the trainer and background) and merged them into one. Also,
    > note that he doesn't actually have aero bars in the last DF photo - we simulated the
    > position by having him rest his forearms on the handlebars.
    >
    > Have Fun,
    >
    > Erich Hartman http://www.hostelshoppe.com
     
  8. Edward Wong

    Edward Wong Guest

    [email protected] (Don) wrote in message news:<[email protected]>...
    > Interesting pictures. Thank you for posting them.
    >
    > One thing to note is that in the two DF pictures on the right the rider could not ride in that
    > position for very long before they would hit a tree, parked car, or find a ditch. In other words
    > they can not see where they are going. The pictures actually slightly exaggerate the DF aero
    > benefit of aero bars or a low position. If riders raise their head to see, they lose some of the
    > aero advantage shown in the picture. Also raising the head can be painful after a while. I know I
    > can not ride in that position for very long. The recumbent style in the picture may actually have
    > more aero advantage over the DFs than it appears.

    There's an older guy in our bike club who has had several accidents because of riding with his head
    hanging downward. One time he actually rear ended a fellow rider who was OFF to the side of the road
    drinking water. This older guy wound up doing an "Arty Johnson" and breaking his hip. Another time,
    he "took out" his wife while he was making a turn. He wasn't looking where she was and they both
    took a tumble. She wound up with some nasty road rash and a cast on her forarm. I bet she wasn't
    happy about this. What's so amusing is that you can see a pained expression on his face whenever
    he's on a road bike and yet one of his most frequent riding buddies is a BikeE RX owner who looks so
    comfortable in sharp contrast to him. This older guy "just doesn't get it":)

    Edward Wong Orlando, FL
     
  9. Rod Dabe

    Rod Dabe Guest

    Seppo wrote

    > At first glance a human being looks at the face or head of the other human
    being. <

    That's not what my wife tells me. <EG>

    Rod
     
  10. Dan Schaper

    Dan Schaper Guest

    Reminds me of those "stages of man" drawings in the evolutionary biology textbooks which start with
    the monkey on the left and end with homosapiens on the right. :)

    dan
     
  11. Jac

    Jac Guest

    Dear Mr. Hostelshoppe: Please send info. on time lapse between photos. Your Recumbent diet idea is
    fabulous. Congratulations. Where can I buy one of these fabulous calorie burning machines?
    Sincerely,
    Dr. Atkins
     
  12. Seth Jayson

    Seth Jayson Guest

    What Seppo's referring to is, of course, perspectival diminution. He's right to note that the effect
    of exaggerating the frontmost portion of the photograph can be minimized by utilizing a longer lens.

    In order to illustrate things more accurately, one would only need include a couple of yardsticks in
    the photographs. One even with the handlebars (say, on the left) and another even with the 'bent
    rider's face. that way, you could see the effect of the diminution due to the perspective/lens used
    to make the images, and you could even do a quick calculation of the frontal area.

    sj
     
  13. John Foltz

    John Foltz Guest

    Good pics, Erich. They show the reduced frontal area of the rider, but what I noticed was the large
    amount of dirty air underneath the rider.

    I'd like to see some more pics, showing various popular configurations. You show an upright and a
    highracer, how about an EasyRacer, a 'standard' SWB, and a lowracer? Maybe even a trike?
     
  14. John Foltz

    John Foltz Guest

    [email protected] (JAC) wrote in message news:<[email protected]>...
    > ... Where can I buy one of these fabulous calorie burning machines? Sincerely,
    > Dr. Atkins
    >

    (Sent posthumously.)
     
  15. Seppo Sarlos

    Seppo Sarlos Guest

    Are you sure your wife is talking about human beings, not male engineers?

    :)

    [email protected] (Rod Dabe) wrote in message
    news:<[email protected]>...
    > Seppo wrote
    >
    > > At first glance a human being looks at the face or head of the other human
    > being. <
    >
    >
    > That's not what my wife tells me. <EG>
    >
    > Rod
     
  16. Hi Seth,

    Yes, I noticed the perceptual "shrinking head" effect too... :) Of course, you never know, this
    could be proof that your head _does_ automatically get bigger when you sit on an upright!

    If it helps anyone, we kept the front wheel in the same spot, with the camera approximately 12 feet
    from the axle and maybe 3 feet off the ground on a tripod(guesstimates). If we have a chance to do
    anything like this again, I'll definately be a little more scientific about it.

    Thanks for all the great comments! -Erich

    [email protected] (Seth Jayson) wrote in message
    news:<[email protected]>...
    > What Seppo's referring to is, of course, perspectival diminution. He's right to note that the
    > effect of exaggerating the frontmost portion of the photograph can be minimized by utilizing a
    > longer lens.
    >
    > In order to illustrate things more accurately, one would only need include a couple of yardsticks
    > in the photographs. One even with the handlebars (say, on the left) and another even with the
    > 'bent rider's face. that way, you could see the effect of the diminution due to the
    > perspective/lens used to make the images, and you could even do a quick calculation of the
    > frontal area.
    >
    > sj
     
  17. Seth Jayson

    Seth Jayson Guest

    > If we have a chance to do anything like this again, I'll definately be a little more scientific
    > about it.

    You're pretty close already. Twelve feet away is a lot better than, say, 6 feet. As you get further
    and further away, the difference between perceived sizes of the head on the df and head on the 'bent
    will diminish. So, if you really wanted, dropping back 30 feet or so and shooting with a longer lens
    would do it.

    Actually, I don't think there's much need to get too worried. The perceived size difference for the
    faces isn't that bad. And the feet on the bent look large. I think that most people notice that
    less, however, because our eyes are drawn towards faces--it's just a human response.

    Still, a yardstick in the same plane as the front of bike and the faces would let you "fix" any
    further pictures, if you wanted, by letting you use photoshop to select, say, the chest and face in
    the 'bent, and scale it up (using the two sticks as a guide.)

    This would give you an image more akin to a proper technical drawing in elevation, where, of course,
    there'd be no perspective.

    sj (who spent far too much time in grad school studying perspective...)
     
  18. Mitch

    Mitch Guest

    Good stuff Erich. Reminds me of the RCN review of the Aero where they had a comparison of the
    Aero and the Challenge Distance (I think). I'd like to see the same type of comparison (as done
    in RCN) between an Aero and a Baron. I think this really shows the "hole" each bike punches
    through the wind.
     
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