How High?

Terminal velocity is dependant on the surface area and drag coefficient of the object. Missiles and airplanes are 'aerodynamic' so their drag is lower...human skydivers fall much faster when in a dive position compared to a spread position, that is to say, their terminal velocity is higher when in a dive position compared to a spread position. If a roller coaster train were made extremely aerodynamic, it would have a higher terminal velocity than Magnum's train. If the train traveled in a vacuum, there would be no Terminal Velocity.

You can't pass out from speed...I fly on commercial airliners regularly and I've never passed out because we were going 400mph.

I lived at 11,000ft for awhile and never did I need oxygen or any other assisted breathing. We're in good shape up till about 17,000 feet, depending on your physical condition.

Just to clear up some of the above altitude misconceptions, here are some facts (as this is my area of expertise):

Skydivers typically jump from an average altitude of between 9,000 and 14,000 feet AGL (above ground level), depending on the plane and how nice the owners are. For skydiving operations, FAA regulations mandate supplementary oxygen for special exits above 15,000 feet MSL (mean sea level), though it is recommended for extended flights above 10,000 feet. One can get a bit woozy while up there for a while!

As for the 120-mph terminal velocity myth that refuses to die, Chris and Seth above got the basics right; elucidating further, a skydiver on his/her belly can typically average between 100-130 mph depending on size/weight/other factors, while a person in a straight headdown position (think a badminton birdie) can go 150 mph and much faster. My fastest speed (many skydivers have a small device which measures it) is 240 mph -- and I'm still typing this response today!

In short, given sufficient pull-out radii to diminish g-forces, the human body can withstand likely any roller coaster we could possibly throw at it (well, maybe not a togo, or a vekoma, or ... but I digress). For lack of knowledge I won't comment on height restrictions, but I'm fairly confident in saying that cost and return on investment will be the limiting factor on coaster height. Unless breaking records is a marketable priority, why build higher if the public will be satisfied with something at -blank- height anyways?

Of course, if you really want to go higher, there's always a plane to jump out of :)

-Skydivin' Jeff

Fact of the matter is Griffing Airport may close in the near future.