Space Elevator

Tim Ward wrote:

Stall speed at extreme altitude would not the benign 180 knots, but
something appreciably higher (can you help me out with the high
altitude
747 data - actual stall speed at FL 450?).

I actually want to fly the 747 pretty fast. If its speed at 45000 feet
is
fast enough so that the spacecraft's airspeed at 100000 feet is at the
spacecraft's best rate of climb speed, then the turning maneuver isn't
required.

pacflyer gave a 1g speed range for the 747 at 45,000 ft and 580,000 lb of
208 kt to 251 kt. I'm assuming those numbers are in KCAS. If so, that
works out to 444 KTAS to 524 KTAS under standard day conditions.

At 100,000 ft, those same true airspeed values work out to 56 KCAS to 68
KCAS. The equivalent airspeed, which is what the wing sees, is a bit
lower at 52 KEAS to 61 KEAS. That means the orbiter needs to have a very,
very low wing loading, which doesn't seem compatible with a re-entry. And
it has to support the weight of the tether too. I'm not sure this idea
will work, unless we can get a much faster tow aircraft.

--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/
e-mail: khorton02(_at_)rogers(_dot_)com

Ahh... at last someone who did what I was too lazy to do... the numbers.
I knew the indicated airspeed at 100,000 feet would be low.

If I can ask a favor, what is the equivalent airspeed at Mach 1 at 100,000
feet, standard atmosphere?

And hey, I've already figured on dropping 20 km of tether, what's a wing
between friends?

Tim Ward

I'm not usually intentionally mean to newbies (well, unless they talk
like tort lawyers wanting a cheap helicopter. And that was more for fun
than meanness).

And I'm not being mean now, Tim. Even if it sounds like it...

The only lazy part here is being too lazy to learn the basic subject
matter before pontificating about it.

The _correct_ question would have been, "What the heck does equivalent
airspeed mean, why is it important, and how do I calculate it?"

I had intended to come back to this discussion and ask if you already
knew that your orbiter was a swing wing design.

But Kevin beat me to it. (From the 3 point line - nothin but net!)


Richard Lamb

"Math - It's not just for sissies any more"