100 MPH (160 km/hr) on 1-hp/746 Watts

[kennybobby]

It takes 2.5 to 3 hp to go 100mph at sea level for a 180 to 200lb, .0005 crr, .10 to .11 cd, 3.5 to 4 sf vehicle.

Going up to 4500 ft drops the air density such that they were able to reach 83mph with the ~1hp (800 watts).

[jamesqf]

Originally Posted by RedDevil

Hey, I did not make that up myself.
Please check the facts at Human Power Team Delft & Amsterdam. There is a wealth of information about the whole event there.

I didn't think you did. Nor do I see a lot of facts about aerodynamics & human physiology at that link. Unless they hid it well, it's just the story of how they built the machine, and what they did at the competition.

I'd also suspect that as this team hails from the Netherlands, they might have a distorted view of what actually is high altitude, and little first-hand experience.

[RedDevil]

From that link:

Each year the cycling teams are given the opportunity to achieve record speeds along a straight section of road in Battle Mountain, Nevada. It’s a fantastic stretch of straight asphalt that’s almost 10 km long. The cyclists have eight kilometres to accelerate and their speed is measured during the last 200 metres.

We Dutch do know what mountains are (incidentally, one of my hobbies when I was single was mountain hiking) there are a lot of fine mountains just within a few hours beyond the borders.

The team went to Battle Mountain because the event is held there. What else can they do?

The inside of the VeloX:
Notice the front wheel is between the riders legs! Not much steering there, won't do U turns.

[jamesqf]

[QUOTE=RedDevil;396230]From that link:

Each year the cycling teams are given the opportunity to achieve record speeds along a straight section of road in Battle Mountain, Nevada. It’s a fantastic stretch of straight asphalt that’s almost 10 km long. The cyclists have eight kilometres to accelerate and their speed is measured during the last 200 metres.

So where in that does it say anything about the location being selected for altitude? I don't see it. All I see is a quote that confirms what I said earlier: the event is held there because there's this long straight & level stretch of road, which has very little traffic so the authorities will allow it to be closed to traffic for the competition.

And far from being chosen because of the elevation, it's actually about as low as any place within several hundred miles.

We Dutch do know what mountains are...

Quite likely you do know what mountains are (though note this event is not held in the mountains, but in a broad valley). All I have said is that if they honestly believe that running the same machine/pedaler combination at sea level will let them get higher speeds, they are sadly misinformed.

[RedDevil]

Originally Posted by jamesqf

So where in that does it say anything about the location being selected for altitude? I don't see it. All I see is a quote that confirms what I said earlier: the event is held there because there's this long straight & level stretch of road, which has very little traffic so the authorities will allow it to be closed to traffic for the competition... ...

Soon after the event, there was a lot of info about it - in Dutch. International media were slow to pick it up and went less deep itto the story (in general, I did not read the entire Internet).

So, does height matter? Was the location chosen for height?

Well, they did try to set the record at sea level. And failed miserably.
See Ligfiets.net | Snelweg dicht voor fietsrecord

In the Dutch province Friesland (Fryslân) an 8 kilometer of highway had been closed to allow for the record attempt. Due to high winds they only achieved 78 km/h, less than 50 mph. But though they expected to go faster than 100 km/h, they did not believe they would break the record there because:

... In de woestijn in Nevada kunnen fietsers sneller, omdat daar minder wind staat en de hoogte beter is.

Yup, Nevada is higher, and that's better.

Another amazing detail; this link not only describes the height of about 1500 meter above sea level as ideal, it also explains the way the pedals in the Velox2 moved around the crankshaft in a flat ellipsoid motion so the rider needed less space for his legs while pedaling, and the body could be kept lower.


This years Velox3 had a normal crankset again as the aerodynamic gain of the ellipsoid system was offset by the added friction and vulnerability.
See http://www.hptdelft.nl/nl/index.php?...d=39&Itemid=50. Sorry, Dutch again; the English page (replace /nl/ with /en/ in the link) is a bit of a stub.

The record attempt at Battle Mountain had almost failed because of the wind. Only on the last day were they able to set te record, despite the still strong wind. And of course the fix against the deforming body shell.
I bet if they try again next year with the Velox4 having a body shell that is properly stabilized and luck with the weather they can go even faster, much faster maybe.

[aerohead]

[QUOTE=jamesqf;396279]

Originally Posted by RedDevil

From that link:


So where in that does it say anything about the location being selected for altitude? I don't see it. All I see is a quote that confirms what I said earlier: the event is held there because there's this long straight & level stretch of road, which has very little traffic so the authorities will allow it to be closed to traffic for the competition.

And far from being chosen because of the elevation, it's actually about as low as any place within several hundred miles.



Quite likely you do know what mountains are (though note this event is not held in the mountains, but in a broad valley). All I have said is that if they honestly believe that running the same machine/pedaler combination at sea level will let them get higher speeds, they are sadly misinformed.

The Human Powered Vehicle Association may be the place to look for the reasoning behind the Battle Mountain site and what sea level would be like.

[aerohead]

Originally Posted by kennybobby

It takes 2.5 to 3 hp to go 100mph at sea level for a 180 to 200lb, .0005 crr, .10 to .11 cd, 3.5 to 4 sf vehicle.

Going up to 4500 ft drops the air density such that they were able to reach 83mph with the ~1hp (800 watts).

I used your rolling force coefficient,4-sq-ft,and Cd 0.105,rho = 0.0020944, and got a road load horsepower of 1.7085 @ 83 mph.
I've not heard of athletes able to produce more than 2-hp momentarily at sea level.
At sea level it looks like you'd need in the neighborhood of 3.132 hp for 100 mph.
Looks kinda doubtful doesn't it?

[Grant-53]

The website recumbents.com is the primary site info on HPV racing and technical articles.

[sendler]

I like the eivie bikes.
.
Eivie III | Eivie
.
.
.
.

.
.