Acabion: very aerodynamic two-seat concept

[RobertSmalls]

In 2006, a Swiss engineer built an enclosed, streamlined, 2+2 wheeled motorcycle with Cd=0.19 and CdA=0.10m^2 (1 ft^2). That's 1/20th the drag area of the Honda Insight, and the best I've ever seen for a two-seater.



Unfortunately, it was not initially concieved as a green or remotely affordable vehicle. It was fitted with a 350HP motorcycle engine for enormous acceleration and the hope of 300mph trans-continental travel. It was supposed to cost half a million Euro. As far as I can tell, that variant never got past the prototype stage.

More recently, its designer has proposed an electric version with a better coefficient of drag and a 300mi range on 15KWh of batteries. The proposed price is still astronomical.

I'd like to see a $20k version, made of steel and fiberglass instead of aluminium and carbon fiber, and with a modest small engine instead of a tuned superbike engine. Such a vehicle should be capable of at least 170mpg at 65mph with 3.5HP, or 70mpg at 120mph with 15HP.

I doubt the Acabion itself will ever be available, but it goes to show you: you can package two people and a powertrain in a streamliner with a CdA of 0.10m^2. That is, if you're willing to give up crash safety, and stability on snow and ice.

[thatguitarguy]

Getting across any continent at 300 MPH on any roadway is ridiculously pie in the sky. I'd say even on a railroad it would be difficult to achieve. And any mishap at that speed in that vehicle would almost surely end in instantaneous death.

Half a million for a motorcycle is pretty pie in the sky anyway. You can buy a pretty fast airplane for that kind of spare change.

I would like to see test results. Those outriggers would never be able to withstand those speeds, so they are obviously retractable for low speed stability, but the entire vehicle looks like it is only designed for straightline speed and not high speed maneuvering.

[Bicycle Bob]

This is an example of a Dalnik, of which the Pereaves Ecomobile from Switzerland is the most successful current example, perhaps superceded now by the Monotracer. I'm sure someone will look it up. However, there is apparently no public evidence of the Acabion being more than a show bike. It may not have a viable steering geometry for lifting those outriggers, according to a friend of mine working on his own version.

[Rokeby]

While I can't find a picture to prove it, I'd bet money that the body is,
or at least is made from a mold taken from, a sailplane. That short stub
high in the rear is I believe where the tail boom would have been.

Here's some pix to support my view:





More pix and other sailplane related stuff to make you drool.

[3-Wheeler]

You know Robert, I have been thinking about converting my present Honda 500 into something like the Gurney Alligator, then adding a third wheel off to one side. This has been on my mind since the Spring of 2007, when the gas first got to $3.50 per gallon.

The object here is two-fold...

1) Provide a motorcycle platform with unparalleled slipperyness for maximum fuel mileage.
2) Provide a third wheel for those days when sidewinds would make you think twice about riding a streamliner with only two wheels.

I may just do something like this after updating the Insight further.

Jim.

[RobertSmalls]

The Acabion certainly does appear to be Suzuki Hayabusa parts grafted onto a sailplane fuselage, being hawked by a charlatan. Still, his Cd*A figure seems about right based on the photos: 0.19*5ft².

The Peraves EcoMobile has been superceded by the Monotracer. Most of the info on either vehicle is in German, including

this 8 minute documentary

. Neither vehicle exceeds the fuel economy of the Honda Insight, and both are absurdly overpowered, with >100HP in a <0.5ton vehicle.

So it looks like, as always, if you want the ultimate efficiency, you have to do it yourself: 214 mpg with DIY aerodynamic fairings on a Honda 125cc motorbike | Hypermiling, Fuel Economy, and EcoModding News - EcoModder.com

I believe a motorized version of this streamlined HPV (my CdA estimate: < 0.67ft²!) would provide better fuel economy than anything else you could build.

[Cd]

The guy has a fairly new video ( all CGI ) of this concept.

Interesting !

https://www.youtube.com/watch?v=ReZ53qOcqfA

[freebeard]

Years ago Popular Mechanics ran a story about a guy on the East Coast (USA) that took a Vespa motor scooter, cut through the floorboard and stretched it 4 feet. It had a rudimentary torpedo body and he claimed 100mph top speed and 100mpg otherwise. I may still have the page buried somewhere, but it's a simple concept.

I understand that there is a problem with 'sit-in' two-wheelers in that you can't throw you body weight from side to side so you have to steer left to turn right; sort of like drifting.

[aerohead]

The students at the University of California at Davis scratch-built their salplane-esque 'Shamu'.They claimed Cd 0.15.

James Bede's Litestar motorcycle-based rig is Cd 0.18 'clean.'

Alex Tremulis was thinking Cd 0.11 for his X200

His X100 was Cd 0.20

Cambridge University really went after the body/wheel integration with the CUER and came in at Cd 0.10.

[cRiPpLe_rOoStEr]

Originally Posted by freebeard

Years ago Popular Mechanics ran a story about a guy on the East Coast (USA) that took a Vespa motor scooter, cut through the floorboard and stretched it 4 feet. It had a rudimentary torpedo body and he claimed 100mph top speed and 100mpg otherwise. I may still have the page buried somewhere, but it's a simple concept.

Ford presented a vehicle conceptually similar to that in early 80's, the Ghia Cockpit. BTW I have been considering to do something like that, but using the engine of a Honda Biz 125.