A kerosene-fueled X-33 as a single stage to orbit vehicle.
in [Physics]
|
Prev: JSH:Twin primes probability correlation
Next: SpaceX says Falcon 9 rocket test fire is a success
From: hcobb on 7 Apr 2010 11:47 On Apr 7, 7:05 am, "J. Clarke" <jclarke.use...(a)cox.net> wrote: > If I understand his notion correctly he's going to put some kind of big > armor plate on his orbiter and then shoot BBs or whatever into the armor > plate to provide acceleration. That part is no crazier than GA Orion. > The problem is getting the BBs to the necessary velocity and aimed with > sufficient accuracy, and his "slingshot around the Earth a half dozen > times to flip the planes of their orbits" sounds on the face of it to be > nuts. > > But if you're going to do it that way why bother with the "Virgin > Galactic style shot", why not use the BBs for the entire flight? > > Engineering questions--(1) how do you accelerate and aim the BBs, (2) > how much armor plate do you need. The BBs are NOT in orbit around the Earth. They're in orbit around the Sun, in Earth's orbit, only backwards. Earth going around the Sun at 30 km/s PLUS BB going the other way around the Sun at 30 km/s EQUALS 60 km/s. The initial boost to get the BBs out of Earth's gravity comes from another such launch. (Since they are hundreds of times more energetic than any chemical fuel you only need a tiny fraction of the mass of each launch to keep up the swarm.) The energy to flip the BB orbits around comes from the Earth's orbit around the Sun. (But it's a very very tiny little fraction.) The guidance for the BBs is that each of them is a tiny little solar sail. -HJC
From: Keith Willshaw on 7 Apr 2010 12:06 "hcobb" <henry.cobb(a)gmail.com> wrote in message news:3ce6440c-7377-43d8-849e-c8cf00b62562(a)n34g2000yqb.googlegroups.com... > On Apr 7, 7:05 am, "J. Clarke" <jclarke.use...(a)cox.net> wrote: >> If I understand his notion correctly he's going to put some kind of big >> armor plate on his orbiter and then shoot BBs or whatever into the armor >> plate to provide acceleration. That part is no crazier than GA Orion. >> The problem is getting the BBs to the necessary velocity and aimed with >> sufficient accuracy, and his "slingshot around the Earth a half dozen >> times to flip the planes of their orbits" sounds on the face of it to be >> nuts. >> >> But if you're going to do it that way why bother with the "Virgin >> Galactic style shot", why not use the BBs for the entire flight? >> >> Engineering questions--(1) how do you accelerate and aim the BBs, (2) >> how much armor plate do you need. > > The BBs are NOT in orbit around the Earth. > > They're in orbit around the Sun, in Earth's orbit, only backwards. > > Earth going around the Sun at 30 km/s PLUS BB going the other way > around the Sun at 30 km/s EQUALS 60 km/s. > But of course at the very best you only get one launch window a year in practise of course given the complexities of the earth/moon orbital path what will happen is a wide miss. > The initial boost to get the BBs out of Earth's gravity comes from > another such launch. (Since they are hundreds of times more energetic > than any chemical fuel you only need a tiny fraction of the mass of > each launch to keep up the swarm.) > But you need a greater energy expenditure to accelerate the pellets to the higher velocity required to leave earth orbit and take up a solar orbit. The principle of the conservation of energy applies. KE = 1/2 m*v*v > The energy to flip the BB orbits around comes from the Earth's orbit > around the Sun. (But it's a very very tiny little fraction.) > This is of course utter nonsense. Gravitational slingshots using the sun itself are not possible because the Sun is at rest relative to the Solar System as a whole and of course you are launching from earth so you cant use it either. Now you could slingshot off Venus but then the resultant trajectory would miss the earth completely. > The guidance for the BBs is that each of them is a tiny little solar > sail. The Solar wind and light pressure stream outward from the sun, your BB's will miss. Keith
From: J. Clarke on 7 Apr 2010 14:54 On 4/7/2010 12:06 PM, Keith Willshaw wrote: > > > "hcobb" <henry.cobb(a)gmail.com> wrote in message > news:3ce6440c-7377-43d8-849e-c8cf00b62562(a)n34g2000yqb.googlegroups.com... >> On Apr 7, 7:05 am, "J. Clarke" <jclarke.use...(a)cox.net> wrote: >>> If I understand his notion correctly he's going to put some kind of big >>> armor plate on his orbiter and then shoot BBs or whatever into the armor >>> plate to provide acceleration. That part is no crazier than GA Orion. >>> The problem is getting the BBs to the necessary velocity and aimed with >>> sufficient accuracy, and his "slingshot around the Earth a half dozen >>> times to flip the planes of their orbits" sounds on the face of it to be >>> nuts. >>> >>> But if you're going to do it that way why bother with the "Virgin >>> Galactic style shot", why not use the BBs for the entire flight? >>> >>> Engineering questions--(1) how do you accelerate and aim the BBs, (2) >>> how much armor plate do you need. >> >> The BBs are NOT in orbit around the Earth. >> >> They're in orbit around the Sun, in Earth's orbit, only backwards. >> >> Earth going around the Sun at 30 km/s PLUS BB going the other way >> around the Sun at 30 km/s EQUALS 60 km/s. >> > > > But of course at the very best you only get one launch window a year > in practise of course given the complexities of the earth/moon orbital > path what will happen is a wide miss. In any case the problem remains, you have to accelerate and aim the BBs and if you're going to put them in a solar orbit how effing many gigatons of them are you going to need in order to have enough of them impact your vehicle to do any good? And if they have that kind of density then what are they going to do to everything else in orbit? The BBs per se are a reasonable notion possibly worth exploring. But having them in solar orbit for whatever reason is just plain crazy. >> The initial boost to get the BBs out of Earth's gravity comes from >> another such launch. (Since they are hundreds of times more energetic >> than any chemical fuel you only need a tiny fraction of the mass of >> each launch to keep up the swarm.) >> > > But you need a greater energy expenditure to accelerate the pellets > to the higher velocity required to leave earth orbit and take up a solar > orbit. > The principle of the conservation of energy applies. KE = 1/2 m*v*v And you have to launch vast quantities of them or aim them with unimaginable precision to have them where they need to be when you need them to be there. >> The energy to flip the BB orbits around comes from the Earth's orbit >> around the Sun. (But it's a very very tiny little fraction.) >> > > This is of course utter nonsense. Gravitational slingshots using the sun > itself are not possible because the Sun is at rest relative to the Solar > System as a whole and of course you are launching from earth so > you cant use it either. Now you could slingshot off Venus but then > the resultant trajectory would miss the earth completely. > > > >> The guidance for the BBs is that each of them is a tiny little solar >> sail. > > The Solar wind and light pressure stream outward from the sun, your > BB's will miss. > > Keith
From: Greg D. Moore (Strider) on 8 Apr 2010 12:23 Robert Clark wrote: > On Apr 7, 12:42 am, hcobb <henry.c...(a)gmail.com> wrote: >> The fix is to get your air launched rocket into space, but not into >> orbit. >> >> It's a Virgin Galactic style shot that just clears the atmosphere at >> roughly zero velocity. >> >> Then bring in stream of tiny impactors at 60 km/s to power an >> ablative rocket and off you go. >> >> At 60 km/s these impactors have 400 times the energy their mass in >> TNT would provide so this is far more energetic than any chemical >> rocket could manage. >> >> Where do you get the 60 km/s? Simply launch the micro-impactors clear >> of the Earth and have them slingshot around the Earth a half dozen >> times to flip the planes of their orbits around until they're >> counterorbital with respect to the Earth and you double Earth's >> roughly 30 km/s orbital speed for the impact. >> >> -HJC > > Please don't give anyone any ideas about hypersonic bb's in orbit > counter rotating to manned craft and satellites. > > Bob Clark Wow, you know your idea must be really out there when Robert pooh-poohs it. -- Greg Moore Ask me about lily, an RPI based CMC.
From: Greg D. Moore (Strider) on 8 Apr 2010 12:25
hcobb wrote: > > They're in orbit around the Sun, in Earth's orbit, only backwards. > > Earth going around the Sun at 30 km/s PLUS BB going the other way > around the Sun at 30 km/s EQUALS 60 km/s. > > The initial boost to get the BBs out of Earth's gravity comes from > another such launch. (Since they are hundreds of times more energetic > than any chemical fuel you only need a tiny fraction of the mass of > each launch to keep up the swarm.) > > The energy to flip the BB orbits around comes from the Earth's orbit > around the Sun. (But it's a very very tiny little fraction.) > > The guidance for the BBs is that each of them is a tiny little solar > sail. > > -HJC Wait, let me get this straight. You're converting the potential energy of the BBs into kinetic energy at the armor plate? And how do the BBs get all this potential energy in the first place? -- Greg Moore Ask me about lily, an RPI based CMC. |