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Landshark
An anonymous reader writes "This has got to be, or will be when they actually make one, the coolest amphibious vehicle around. It's a cross between a motorcycle and a jet ski, and it seats three. It can travel at 200 mph on land and 50 mph on water. Just what you need to get you from point A to point B."
A boat is designed to be a wing. You want the least amount of boat in the water that you possibly can, so you construct it to lift up and out the faster you go. But on land, you want the vehicle to press down onto the ground, the opposite direction as in the water.
Like the space shuttle, this "landshark" sounds like it was engineered for coolness and not from genuine requirements.
Reading that last line on Landshark's homepage, I can only think of the next round of Darwin awards and wonder if should inform Mr. Baker of his nomination. ;)
Here's the google cache if you need it
Actually, the current land speed record holder is a three-wheeled gas turbine powered vehicle. Two wheels up front and a pair of co-linear wheels in the rear.. They had some stability issues at the prototype stage, but the car that they ultimated ran worked fine..
I'd rtfa but the bugger's slashdotted.
.29 Cd vehicle, with a TON of aero work can do this pretty calmly. Take that exact same envelope to 195 or so and it's aerodynamics are no longer adequate to task, it's gets pretty hairy handling. (and takes 575 hp...more than the neon because it punches a bigger hole in the air, and there are differences in driveline efficency and gearing)
;)
be that as it may, it's _extremely_ difficult to make a vechicle do 200mph sustained. You can do it one of two ways:
a)Serious Cubic Horsepower
b)Serious Aerodynamic design
If you choose 'a' above, be prepared to generate 600+ hp, also be prepared to protect your occupant when the vehicle loses directonal stability.
If you choose 'b' above, you may be able to get along with significantly less hp (400-500), but be prepared to spend cubic dollars renting a wind tunnel, or hardware/software to perform a lot of number crunching.
Remember, HP goes up with the _cube_ of speed change. If your car does 150mph with a 215hp motor (Turbo Neon, this month's Road n track) and you want it to go 1.33 times faster, it'll take 1.33^3*215hp or 505hp to make 200 mph...
An additional datapoint: My vette has done 168mph with 350 crank hp (automatic, nevada, coupla thousand feet above sealevel, so figure some hp loss there.) So a
You go ahead, I'll watch from a safe distance.
"Draco dormiens nunquam titillandus."
I doubt top speed will be 50. I've owned Jet Skis, and one thing you learn about is cavitation, and something call the Scoop Grate.
Basically, the stock setup that came with my KW-650SX goes barely 40Mph. But it was because at 40Mph, not enough water is going through the impeller. So, with the simple addition of an after market scoop grate, I added about 3Mph (All it did was lower the scoop about 1/4 an inch. I got another 2Mph out of a stainless steel prop, and anouth 2Mph out of a new ride plain.
Pulling in water as it passes alog the side of a wheel just won't work.
It's a really cool design though to have the wheels sucking in water to pump out, but he really needs to redesign. Basically, you need to scoop the water in.
Also, since it's a fairly heavy thing, it can actually go faster on water that 50Mph because of the added stability. My stand-up jet-ski weighs about 260lbs and at 46Mpg its a not a pleasure cruise, but on a heavier 550lbs waverunner it is a pleasure to cruise at even 50Mph.
Rethink the water intake to something more direct and it'll go more like 75-95 on water. Horseopower isn't the issue, fluid dynamics is.
Three wheeled recreational all-terrain-vehicles (ATV's) were very popular in the 1980's, until people got tired of broken arms and collar bones from when they rolled in sharp turns. Almost all of the ATV's sold today are four wheelers.
Think outside the... Hey, where'd the friggin' box go?