by the way, why arent sattelites injected directly to geosynchronous orbits?? why do they must first go to LEO and then use a transfer orbit???
thks!!! and about the first question?? would be possible???
My question is how is that accomplished with a solid fueled upper stage, for example, a Castor 30.
1) Does it (or would it) ever make sense to launch an orbit-bound rocket at an acute angle with respect to the ground?
I think they may have meant that the orbits get bulges at 75 and 225? Or, it may be that the Geoid is low there because the seafloor is higher density than land, and so has a larger effective gravity...
In fact, there are two “bulges” along the Equator at approximately 75° and 225° East longitude. These gravity “troughs” pull satellites in geostationary orbit east or west towards whichever is closest, giving the satellite an apparent east or west drift.
Quote from: Nascent Ascent on 01/11/2009 09:53 pm1) Does it (or would it) ever make sense to launch an orbit-bound rocket at an acute angle with respect to the ground?Japan's M-V was launched that way, from a launch rail (see photo). I believe that NASA's Scout may have also been launched tilted slightly from vertical. Pegasus, of course, is nearly horizontal when dropped. - Ed Kyle
You know the rocket equations that say how much of a SSTO would have to be fuel to achieve orbit at Earth? (I think it is about 80%) Anyway, I was just wondering what percentage of a SSTO taking off from Mars would have to be fuel.Thanks in advance
From my (very rough) calcullations, for LOX / LH2 (isp 460 sec.) it would be about 54.5%. Perhaps more realistic isp 448 sec. gives you about 55.4%. But if you'd like to use liquid methane (isp at ~380 sec.) instead of LH2, your percentage rises to 61.5%. Note that these figures don't take into account the atmosferic drag, trajectory shaping, etc.
Quote from: Heg on 01/28/2009 02:19 pmFrom my (very rough) calcullations, for LOX / LH2 (isp 460 sec.) it would be about 54.5%. Perhaps more realistic isp 448 sec. gives you about 55.4%. But if you'd like to use liquid methane (isp at ~380 sec.) instead of LH2, your percentage rises to 61.5%. Note that these figures don't take into account the atmosferic drag, trajectory shaping, etc.A more fun number would be what is the mass fraction required for SSTER (Single Stage To Earth Return)
Some materials and electronics are sensitive to helium too.
Quote from: Antares on 02/21/2009 06:03 pmSome materials and electronics are sensitive to helium too.Sensitive to helium in what sense? It's supposed to be an inert gas. Diffusion problems?