Posted on 06/04/2012 6:03:18 PM PDT by BenLurkin
/johnny
Haven’t seen that sales number in a long time, what’s the special? :-)
The X-37B Orbital Test Vehicle sits on the runway at Vandenberg Air Force Base, Calif., Dec. 3, 2010, during post-landing operations. Personnel in self-contained atmospheric protective ensemble suits are conducting initial checks on the vehicle and ensuring the area is safe. The X-37B launched April 22 from Cape Canaveral, Fla., allowing teams to conduct on-orbit experiments for more than 220 days during this first mission.
For a circular orbit, the required speed is : v = sqrt(mu/r)
where mu is the gravitational parameter and r is the orbital radius. mu = GM, where G is the universal constant of gravitation, M is the mass of the central body (technically it should be M+m, but we assume m small relative to M).
so if v = 17000 mph, then r is 1.0820655*re (re = radius of Earth, I solved this using canonical earth units, it’s easier). This means the orbit is 324.98 miles up, which is very reasonable (I believe the space station is 230 miles).
Atmospheric drag is a drag.
I limited my calculations to 1.08(something) because I'm just a cook, and 6 decimal place accuracy seems come-uppish for a cook. 2 decimal places seemed appropriate. I'm glad to see my decimals were probably correct for the problem. At least within an order of magnitude, and having a relationship to reality that didn't have us orbiting in rock or near the moon.
/johnny
Yeah, no problem on the decimals, I just reported what matlab spat back. I just wanted to verify your work since I didn’t particularly like the method I saw being used (using surface gravity). Not sure if that was yours or dr’s (have to go back and look).
I’ve worked on the ISS program actually. I know all about the headaches they go through positioning solar arrays and reboosting the station. Fun times :)
My formulas are all from very, very old books. Think steam engine old.
/johnny
(1/2)mv^2 is an energy equation. Force is equivalent to mass multiplied by acceleration, not mass multiplied by speed squared.
Lol, no problem, orbital mechanics hasn’t changed much in decades anyway. When I took it (and when I taught it this past spring) I used a book from 1971: Fundamentals of Astrodynamics. It’s an excellent book for basic orbital. And since so much of the 2-body problem is geometry, it’s easy for anyone to understand.... well anyone who knows geometry.
Oh, brother! Now I’m getting blamed for this one!
LOL!
Which hydrazine? Monomethyl or UDMH?
The H202 is probably closer to 95% if they want the optimum fuel to oxidizer ratio and propellant Isp.
Probably MMH, it has ha higher specific impulse.
The Hydrazine family is always taking the wrap for something!
LOL!
The Hydrazine family is always taking the rap for something!
LOL!
Yes it is. Either their speed data is wrong or it was a powered orbit, not just standard freefall orbit
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