British company White Motorcycle Concepts (WMC) says its WMC250EV should be capable of more than 250 mph (402 km/h) thanks to a massive 69 percent reduction in drag — from being designed around a giant hole:
Going super fast ends up being much more about aerodynamics than horsepower; the air becomes a ferocious adversary as you move past two or three times highway speed. Motorcycles are aerodynamically ugly without big, streamlined fairings, chiefly because of the big, funny-shaped human on the back.
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WMC has tested this bike, Rob included, at the Horiba MIRA facility near Hinckley, and says the concept reduces drag by an enormous 69 percent compared against “the world leading motorcycle,” with a drag coefficient of just 0.118. That’s absolutely nuts. Even the mighty SSC Tuatara, currently the world’s fastest production car at 282.9 mph (455.3 km/h), can only manage a drag coefficient of 0.279.
In order to run that big hole through the middle, WMC has had to jam all the guts of the bike into the space under the tunnel. That’s not just the electric drivetrain and battery packs, either; the tunnel cuts right through where your steering head and forks would normally be.
So the design uses a double-swingarm suspension system. The rear wheel is chain-driven by a pair of 30 kW electric motors integrated into the swingarm, according to Top Gear.
The front wheel is hub-steered using a hydraulic system that completely replaces the mechanical linkages you’ll normally find between the handlebars and front axle on a hub-steered bike.
A number of years back some genius in NASCAR ran his exhaust pipes directly out the rear, using the exhaust volume to partially fill the low-pressure area immediately behind the car, reducing vacuum-induced drag. Other racers complained because 1) they hadn’t thought of it, and 2) the hot exhaust caused their cars to overheat when they drafted the genius. NASCAR immediately banned it, which is why every car in NASCAR must have the exhaust exit in front of the right rear wheel.
Engineers put no small amount of effort into making NASCAR race cars more aerodynamically “pure,” preventing as much air as possible from getting under the car (air dams) and making the underside as smooth as possible.
I’m sure NASCAR has (or would immediately make) rules against it, but I’ve wondered why no one has tried a “center tunnel” through the car to exhaust radiator cooling air into the vacuum behind the car instead of “dumping” it under the car at the firewall. I’d think that, plus engine exhaust, to fill the partial vacuum there (and eliminate some of the air under the car) would be worth several miles per hour.
I wonder if anyone here knows why the tunnel is better? I’m assuming the same cross section or frontal area. If you put a tunnel in then…why less air friction by a large amount? Could it be related to vortex rings? Vortex rings lower drag and a tube could be one way to form them.
A idea. If it “is” vortexes, could you not cover the body with a lot of vortex creating rings, think golf ball covered with dimples but vortex rings in place of dimples. Open the front up and channel air around the body and exit in the vortex rings all over the body.
They have something similar for RV’s and trucks, called Airtab Fuel Savers, vortex generators. I read reviews on these and found high positive feedback.
I’ve looked a lot of places and all the tunnel effects I have seen on race cars deal with creating down force. None of them say anything about reducing drag. I don’t understand how this works “IF” the frontal area is the same hole or not.
Blank Space,
Might work. Basebleed artillery rounds work on that principle
“Basebleed artillery rounds work on that principle.”
I don’t believe you are correct about this. Gerald Bull, I believe, invented this or at the least had a great deal to do with it. He sold a bunch of artillery to South Africa based on this. Of course the Jews killed him when he started working wit Saddam. I read a book about him,”Bull’s Eye: The Assassination and Life of Supergun Inventor Gerald Bull”.
Base bleed leaks hot exhaust gases from a small reservoir full of some sort of fuel.
https://en.wikipedia.org/wiki/Base_bleed
This motorcycle best as I can tell is just a hole. Now if they are pushing the exhaust through it then I understand completely. It’s called “air augmentation” and is used in some rockets but they say not a word about this.
I just happened to remember that the P-51 mustang had a system where the heat from the radiator added a LOT of power by heating incoming air on a duct and releasing it[Meredith effect]. Quote,”…So this meant that while (compared to a standard radiator) the Mustang radiator had a radiator drag reduction at high level speed of 90%…North American calculated that the Mustang’s radiator was worth 200bhp to it…”
https://www.quora.com/Was-the-P-51s-cooling-system-designed-to-take-advantage-of-the-Meredith-effect-and-produce-jet-thrust-or-was-it-just-by-accident?share=1
Maybe this is it. They are running the engine heat and radiator through the duct. 200bhp for the plane is a whopping big figure. Maybe they are ding the same with the motorcycle.
The idea is to reduce the partial vacuum behind the vehicle, either by a hole through the middle, or leaching gas into it.
Alistair says, “The idea is to reduce the partial vacuum behind the vehicle, either by a hole through the middle, or leaching gas into it.”
I fully get the “pushing gas” behind it part. In this case I assume if they ARE pushing gas it is heat from the engine and exhaust. That part I fully understand how it works. What I don’t get is if they are NOT pushing gas and just have a hole then why is the wind resistance drastically less? Assuming the cross sectional area is the same then why would a hollow cylinder give less wind resistance than a round object like a solid bullet.
While I was writing this I happened to remember this weapon.
Ring Airfoil Grenades
https://www.angelfire.com/art/enchanter/RAG.html
These supposedly went farther, straighter and were more lethal. They do not answer the question if the cross sectional area is the same. They say it has less drag because of the hole but, so what, if there’s less cross sectional area then having a hole or not means nothing.