Interesting Aerodynamic Cars (Mike Vetter's ETV, also Avion)

[sendler]

Originally Posted by jjackstone

photo of the Eta

Is the pointy nose really faster than an air foil nose in 90 mph air? Because there is a big draw back in handling side winds when there is that much overhang ahead of the front wheel. And it looks like the shape at the back narrows into a J form too quickly to maintain attachment. Is there a rule as to why the body had to be so short behind the rear wheel?
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Speed-bikes
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It looks like it would actually have lower drag in reverse.
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Aerovelo
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[kach22i]

Originally Posted by jjackstone

Here's a link to their site. Aerovelo

Cool, thanks.

I can now see the flat screen inside which must allow for a view ahead.

Kind of miss the fin and maple leaf though.

EDIT: Found this............
http://www.bloomberg.com/news/articl...highway-speeds


EDIT-2: Various competitors......................differing approaches.

https://jnyyz.wordpress.com/2015/09/page/4/

[jjackstone]

Originally Posted by sendler

Is the pointy nose really faster than an air foil nose in 90 mph air? Because there is a big draw back in handling side winds when there is that much overhang ahead of the front wheel. And it looks like the shape at the back narrows into a J form too quickly to maintain attachment. Is there a rule as to why the body had to be so short behind the rear wheel?
.
Speed-bikes
.
It looks like it would actually have lower drag in reverse.
.
Aerovelo
.

In these bikes, the widest spot is usually where the rider's shoulders are which is normally near the rear of the bike. So as I understand it, the front end of the bike is designed to provide laminar airflow as far back as possible and the short rear end is to minimize skin friction and help with pressure recovery. As you noticed the shape doesn't match the standard teardrop shape template so often used on this site. All I know is the results. These guys added over 3 mph to a record that had been increasing by maybe a half mile per hour every couple years for about a decade. The speeds are attained on less than 1 horsepower for the most part. There are a few very strong riders that can put out more power than that for a short time period.

The bikes aren't particularly stable and a good wind can easily send someone off into a ditch. But they are made for one thing... that's going fast in a straight line. Normally no one will ride if the wind is much more than 8 to 10 miles per hour. Too dangerous.

JJ

[jjackstone]

This is one of my favorite bikes and rider. Damjan actually rides the thing backwards lying on his back. He uses a mirror looking out a small hatch in the top of the bike to see to steer. His top speed is "only" 80 mph.



JJ

[freebeard]

Interesting aerodynamic bikes...


https://4.bp.blogspot.com/-6Xj8LA1RA...0/monster9.jpg

[Frank Lee]

The idea behind having max width more rearward than "our teardrops" is to achieve more true laminar flow over a greater percentage of the form.

[sendler]

Originally Posted by jjackstone

This is one of my favorite bikes

The EiviE is way more aero but needed a bigger rider.
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I'm surprised that none of these human powered machine teams ever seem to hire a pro level sprinter or track racer which are able put out more than 2hp for 30 seconds at the end of a grueling 150 mile race.
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[gafhj]

Originally Posted by sendler

The EiviE is way more aero but needed a bigger rider.
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I'm surprised that none of these human powered machine teams ever seem to hire a pro level sprinter or track racer which are able put out more than 2hp for 30 seconds at the end of a grueling 150 mile race.
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Graeme Obree and Jason Queally had tried and failed badly.
Obree had quite amateurish bike. He wanted to win by using prone position which failed.
Queally insisted on spacious interior, so he could produce all his power which killed his drag area.
And Todd is actually better for the task than most pros - because he's a pro trained for top power for 30 seconds w/out a 150 mile race before.

Added:
http://www.recumbents.com/wisil/fastest_list.asp
Queally is a 3 hp engine, yet made 103 km/h. That's 26 below the record at the time.
Obree made 91.

[Grant-53]

The shape is similar to the fuselage of high performance sailplanes.

[aerohead]

Originally Posted by sendler

Is the pointy nose really faster than an air foil nose in 90 mph air? Because there is a big draw back in handling side winds when there is that much overhang ahead of the front wheel. And it looks like the shape at the back narrows into a J form too quickly to maintain attachment. Is there a rule as to why the body had to be so short behind the rear wheel?
.
Speed-bikes
.
It looks like it would actually have lower drag in reverse.
.
Aerovelo
.

I agree with all the members who've already mentioned laminar boundary layer bodies.
The Delft team told me that this was the premise for their designs.
Keeping the max cross-section aft held the forebody in a favorable pressure gradient for laminar boundary layer (low skin friction),The turbulent boundary layer transition was held far back on the body,and so much kinetic energy was available in the TBL due to the forebody,that more aggressive curvature in the rear (reduced wetted area ) could maintain attached flow.
This is all predicated upon 'calm' conditions.Once the wind comes up,the body in immersed within Earth's turbulent boundary layer,and the ambient air turbulence kills the laminar boundary layer,especially in a crosswind which contaminates it,forcing an immediate TBL transition.
Keeping the envelope as small as possible (length) helps because it directly affects Reynolds number,of which LBL is directly related.