Will this be orbital or sub-orbital?

[ryan]

Hey guys can you imagine the rocket that will be able to do it, its hard enough for a rocket or shuttle to get into orbit, but to get out the atmosphere and the earths gravity in one shoot. The rocket will be like 5 saturn V. Play a practical joke on your friend and tell him or her to stand there and then you run away and the rocket lifts off. You come back and your friends not there he or her got blown away and crashed into the VAB.

 

[tomek]

Assuming you manage to run away...

I think that if you go straight up, you do carry with you the velocity of the Earth's rotation.(The reason most spacecraft launch east) If you assume that this velocity is about 465.11m/s I think that you can get into an orbit of about 146M x 200km if you go DIRECTLY up from the equator with 0 inclination.
NOTE: Keep in mind that before and after apogee you will appear to be moving west because you are moving slower than the Earth's rotation. You will stay in one spot above the Earth at apogee because you are moving at the same rate as the Earth rotates.

If you launch vertically you won't be moving at apogee at the same rate as Earth rotates. Your velocity at apogee is minimal, whereas linear velocity needed to maintain the same angular velocity actually increases with distance. You'll be moving west from the moment you lift off.

 

[ryan]

Hey guys is this even possiple in the real life, ive done it in orbiter but i havnt seen it done before with NASA or someone else.

 

[Quick_Nick]

Hey guys is this even possiple in the real life, ive done it in orbiter but i havnt seen it done before with NASA or someone else.

Well, there's really no practical use and it uses loads of fuel. And if your flight ends up really suborbital you'll have a terrible reentry. You might get a shallow reentry if you went high enough with my plan, but tomek seems to disagree with the possibility of it. However, if you broke the rule of only burning vertically, you could change your suborbit to an orbit or to a shallow reentry by burning laterally for a short time at apogee.

 

[Urwumpe]

Well, my concept of inserting into a Orbit with periapsis altitude around 20 km works out, but it has the same disadvantage - it is very ineffective - even a fractional orbit with a dogleg maneuver is more effective.

But well, it is a cool training for reentering from interplanetary trajectories. If you can reenter after such a 24h orbit, you can reenter when coming back from mars.

 

[tomek]

You might get a shallow reentry if you went high enough with my plan, but tomek seems to disagree with the possibility of it.

I actually disagreed with your statement about not moving with respect to Earth surface at apoapsis. Though now that I think about it seems possible too if Ap is at the right altitude. I don't know what I was thinking. I probably need to get some good sleep, then post, not the other way around.

As for shallow orbit thing... You do indeed get few hundred m/s from Earth rotation at start. If you still had same few hundred meters at the apoapsis, you would probably get a shallow reentry. However, I tend to think that most of that velocity will be canceled by gravity as you rise, because as you shift, direction of "down" changes, and more and more of that horizontal velocity becomes a component of vertical velocity.

I'm not sure I can explain it easily, but here's an intuitive reasoning - the point where you finished your last burn is always part of you current orbit. And in our case, that point is somewhere near the surface, right below us. Whereas to get a shallow reentry, you'd need your periapsis on the opposite side of the planet. It's simply impossible to have a low periapsis, high apoapsis, and low-altitude point right below apoapsis all at the same time. Such orbit would look something like a circle with a spike, not an ellipse. So yeah, you'd need to burn at periapsis at least a few m/s to get a shallow reentry.

 

[Quick_Nick]

I think I see what you mean about the low-altitude point at the end of the burn. I'll try to figure out some of this tomorrow. But I think you misunderstood what I was talking about when I mentioned a shallow reentry. I meant it as a regular reentry from orbit, assuming that my plan will get you into an orbit of many megameters by a few hundred kilometers. I just meant that you'd wait for apogee, as usual, and burn retrograde, as usual, to lower your perigee into the Earth's atmosphere, as usual . When I mentioned a violent reentry, that was assuming that you don't get a high enough apogee or my plan simply doesn't work and you fall straight back towards Earth from high altitude, which may result in directly impacting the atmosphere at 10+km/s.(suborbit from the start) And my statements were just statements. I wasn't trying to describe my plan, I was just giving points about what could be major downsides to using a plan of vertical flight to high altitude.
EDIT: Can someone just make an addon that makes a vessel maintain exactly 90° pitch? It would be really helpful.

 

[Mission_CDR]

I didnt read all of the replies so I do not know if this has been said.

Technicaly evrything is in orbit or sub-orbit, when you jump you travel in an eliptical path just like an orbit until the ground stops you. There is no real difference between orbit and sub-orbit, except for the fact that an orbits path will never touch the ground, so I would not consider that picture an illustration of an orbit.

 

[Quick_Nick]

True. The only other thing I can think of besides an orbit or suborbit is an escape trajectory, and even after escaping a body you'll be in the orbit of a larger body(Earth->Sun->Center of galaxy, etc.). Nothing else really exists when talking about a single body.

 

[Lunar Pilot]

Reentry

You all realize what happens if you hit the atmosphere fast enough with a DG? Right? I've done it with Jupiter once, I upped the time a bit to make it more dramatic, and the next thing I know, I'm speeding out of the atmosphere at twice the speed of light.

 

[mjessick]

A two body orbit that goes straight up then falls straight back down I've seen called a "degenerate conic". (It is the other case besides a parabola that has an eccentricity of 1). This is one of those trick questions you can tease graduate students with

 

[Andy44]

So, then, I suppose that if you built the proverbial tunnel through the center of the Earth and jumped in, hoping to grab the rim at the other side, you'd...what? Bang into the tunnel wall after falling for several minutes due to the Earth's rotation? This would be the extension of mjessick's degenerate conic, but unless you can stop the world from turning, you'd never really get to play with it properly.

 

[Urwumpe]

You all realize what happens if you hit the atmosphere fast enough with a DG? Right? I've done it with Jupiter once, I upped the time a bit to make it more dramatic, and the next thing I know, I'm speeding out of the atmosphere at twice the speed of light.

You should make sure that Jupiter HAS an atmosphere.

The default Jupiter in Orbiter does not have an atmosphere.

 

[cr1]

Does a 85000 second orbit like you described have an apogee inside Earth's SOI?
Sorry if the answer is obvious, but I haven't really been outside Earth orbit until now.

 

[Urwumpe]

Does a 85000 second orbit like you described have an apogee inside Earth's SOI?

Yes, easily. It has a slightly lower semi-major axis as geostationary satellites (These have 86400 seconds orbit period), so it can maximal be less than twice as far away from Earth as geostationary satellites. Or about 75000 km,

I did now not do exact calculations, as the rough estimate was enough for answering the question.

 

[Lunar_Lander]

I once made a similar trajectory with the Project HARP addon. Pointed the gun straight up, set 600 m/s muzzle velocitity and fired the three stages of the Martlet 4 right one after another, still at 90° pitch.

I reached up to 7000 km altitude with that. Flight time was about 60 minutes and then a very rapid and short re-entry with unbelievable loads (I hit the atmosphere with like -7 km/s). I proposed that as a new method for a near-Earth probe (search for "Project Fire Rain" here in the forums).