Mike Painter said:
I'm not sure why 183 feet per second makes more sense than 227 feet per second.
Because of the curvature radius on Interstate highways. At 125 mph you can take most of the curves under most conditions. At 155 mph when the centrifugal force is over 50% greater you can't. Also, there are few tires rated for 155 mph but plenty rated for 130 mph.
Note that I also said 125 mph would be for very lightly traveled highways under ideal conditions. For most Interstate highway driving, I'd say 100 to 110 mph about the limit of reasonable and prudent.
It takes thousands of pounds of force to tear the door off a hinge or free it from the "nadir pin"
I don't know about that. My cousin ran into an open car door on his
bicycle at about 45 mph and tore the door right off. Surprisingly, all he got from the crash was a little road rash. He wasn't wearing a helmet, either. I don't know what kind of car he hit. Might have been an econobox.
offroadcmpr said:
There are plenty of motorcycles that can hit 130 mph in a quarter mile, so a in a mile it might be possible to hit 155.
turbodog said:
As far as acceleration. You're kidding right? These bikes will do 0-60 mph in 2 seconds or under. 155 doesn't take much longer to reach.
OK guys. Let's have a couple of physics lessons. First of all, no matter how much power a vehicle has (or more accurately torque which in turn translates into tractive effort), you're ultimately limited by the tire adhesion. On dry pavement with sticky tires figure an adhesion coefficient of 1, which translates to a maximum possible acceleration rate of about 22 mph/sec. That means 0 to 60 mph in 2.7 seconds
at best, and probably about 3 under real world conditions. Assuming a constant acceleration rate, you would use up about 132 feet of that quarter mile getting to 60 mph. Assuming that you have enough power to hold the same acceleration rate (20 mph/sec) you'll hit the end of the quarter mile at 190 mph except that you run into two problems. First off, to hold an acceleration rate of 20 mph/sec at 190 mph you would need 922 HP per ton of mass. Let's say the bike plus rider weighs 600 pounds. You would need 277 HP. I don't think I've heard of a street motorcycle with even 200 HP. Second, these figures are only relevant with no drag. As we all know, bikes aren't particularly aerodynamic. Between tire and air drag you're probably already using about 60 HP just overcoming drag at 100 mph. That's 60 less HP you have to accelerate with. Going with these real world examples, and even assuming a ridiculous overpowered (for a motorcycle) 200 HP and 600 pounds, by the time the bike hits 100 mph it can't hold the 20 mph acceleration rate any more. You end up with 0-100 mph in 5 seconds and 367 feet. Taking this further, at 120 mph your acceleration rate drops to about 12 mph/sec and at 140 mph it's down to ~5 mph/sec. At 150 mph you'll be lucky to do 2 mph/sec. Aerodynamics can improve the high-end figures somewhat, but the point remains that sooner or later the acceleration rate dies off, and this happens at the top end when you're moving rapidly, so it takes a long distance to eek out those last 20 or 30 mph. In fact, I suspect that most likely 155 mph is the absolute top end of that bike, and it reaches that speed mostly due to some attempt at streamlining (previous example assumed a brick). Therefore, you probably have only 100 HP, so figure rough acceleration rates as follows: 0 to 60 mph-20 mph/sec, 100 mph-10 mph/sec, 120 mph-5 mph/sec, 140 mph-2 mph/sec, 150 mph-1 mph/sec. This gives you a rough distance of about 3400 feet and about 21 seconds to hit 150 mph, and another ~2200 feet to hit 155 mph. In other words, better than a mile and over 30 seconds elapsed time.
How do you expect control your bike at that speed? Especially when everyone else is going third of your speed.
That's the point. Even if the bike could hit 155 mph in 1/4 of a mile you're bound to run into something long before then on a road with intersections and traffic. That's why I don't find this scenario believable. It seems manufactured by someone with a big axe to grind. What's the point? Don't go 155 on roads with intersections? Even an idiot knows that. Or maybe a message to motorcycle manufacturers to not make bikes which can reach such dangerous speeds so quickly? Perhaps, but why not just come out and say it? Fact is people wouldn't be going dangerous speeds as often if they drove vehicles which simply couldn't reach those speeds as quickly. Physics is why. If your vehicle can only hit 30 mph before the next red light gets you you won't be doing 60 mph playing the red light grand prix. Maybe not as exciting, but I fail to see why the general public should have vehicles available to them which offer near race-track performance without requiring the requisite training and discipline. And don't even get me started on all those dumb car commercials showing people driving like idiots, along with an almost microscopic disclaimer ("This commercial done on a closed course by a professional driver. Follow your local traffic laws") to cover the car company's behind.
