Just had an interesting read in ESPN magazine on human powered vehicles. The land class record holders are, of course, recumbent bicycles with ridiculously low drag. I was a little stunned at how far they have come since I last saw some of these in 1990.
The current record is 81 MPH! (200m trap, running start).
The current 1 hour record is 53.5 MPH.
Taking it from where I remember this, a fit human racer can sprint at about 2 HP and sustain about 1 for any length of time. The numbers above work perfectly for .9 HP=53.5 MPH and 2.1 HP for 81 MPH.
Anyone for 200 MPH on 13 HP?!!!!!!!!! The current record holder is a small guy riding a vehicle where they clearly traded off some wetted area for his small size. This reduced the total surface area. They seem to be running about 70% laminar flow on the vehicle sides and have stuck the canopy at the far back to reduce wetted area vs. having a longer laminar run like their nearest competitor.
The obvious advantages of these designs vs. common LSR are IN ORDER:
1. Absolute minimum separation: No blunt rear ends, minimal wheel openings, fairings in front and behind the tires.
2. Ground clearance: "ground effects" may sound sexy, but they are high drag. If we need downforce, we should use a low drag wing, high up in clean air like Teague did.
3. Absolute minimum wetted area: They are SHORT! Shorter means more aggressive pressure recovery, the first trade-off.
4. Significant percentage of laminar flow: Up to 60% of the record holder's wetted area is in laminar flow with favorable pressure gradients and no joints, hatches, vents, or other BS to trip the layer to turbulent.
Sites to check out are:
www.ihpva.organd pictures of the best of the best:
http://www.speedbikebgl.de/eng/sbc2004e.htmlAnd the open motorcycle guys could use some of these tail section ideas:
http://www.speedbikebgl.de/eng/galeriee.htmA lurker on this site who's a race HPV builder contacted me on the side, I think there's still some speed to be had in these things...