So what would happen if.......

[Mag40]

.....a Saturn V had taken off due East from Florida?

I know the mechanism whereby an object in orbit goes around in a large circle......so I'm interested to understand how the rocket would be drawn into that large circle from what starts off as segmental orbit.

[ka9q]

I'm not sure I understand you. By taking off due east from Cape Canaveral, a rocket is following a great circle route. It doesn't maintain this due east orientation, however, any more than a ship or aircraft on a long voyage maintains a constant compass heading all the way to the destination even if it does follow a single great circle route.

[Count Zero]

.....a Saturn V had taken off due East from Florida?

It's S-II center engine would cut-off early and the CM would suffer an oxygen tank explosion.

http://history.nasa.gov/SP-4029/Apollo_18-21_Earth_Orbit_Data.htm

 

[Echnaton]

I'm not sure I understand you. By taking off due east from Cape Canaveral, a rocket is following a great circle route. It doesn't maintain this due east orientation, however, any more than a ship or aircraft on a long voyage maintains a constant compass heading all the way to the destination even if it does follow a single great circle route.

Are there any directions that that a rocket could not use to launch into orbit? No just the Saturn V, but any hypothetical rocket.

[smartcooky]

I'm not sure I understand you. By taking off due east from Cape Canaveral, a rocket is following a great circle route. It doesn't maintain this due east orientation, however, any more than a ship or aircraft on a long voyage maintains a constant compass heading all the way to the destination even if it does follow a single great circle route.

Are there any directions that that a rocket could not use to launch into orbit? No just the Saturn V, but any hypothetical rocket.

I was under the impression that most launches start off by pitching in an easterly direction because they are utilising the rotation speed of the earth. At the Cape, the rotational speed of the earth is about 1400 kph. Launching and pitching toward the west would be problematic as you would be working against the earth's rotation so you would need more fuel plus longer burns to achieve the same orbit (retrograde)

Of course, more fuel means more weight which in turn means more fuel. I would think the weight+fuel impact of needing to find an extra 2,800 kph* to achieve orbit would be significant, because that is around 10% of LEO speed.

* its 2800 kph because you need to make up the 1400 kph you lose by not going eastwards, plus an extra 1400 kph to make up for going against the earth's rotation.

[cjameshuff]

Are there any directions that that a rocket could not use to launch into orbit? No just the Saturn V, but any hypothetical rocket.

Roughly half of them, assuming you start from ground level. Possibly less depending on surrounding terrain.

[Mag40]

I'm not sure I understand you. By taking off due east from Cape Canaveral, a rocket is following a great circle route. It doesn't maintain this due east orientation, however, any more than a ship or aircraft on a long voyage maintains a constant compass heading all the way to the destination even if it does follow a single great circle route.

Florida is at 28 degrees latitude.....if a rocket flies due East and maintains(or at least tries to hold) that direction.....it is following a path 5 degrees North of the tropic of Cancer. That is not a great circle.

I'm just interested in the orbital mechanics that 'force' the craft into a large circle. Is it a greater gravitational force to its starboard side?

[Echnaton]

Are there any directions that that a rocket could not use to launch into orbit? No just the Saturn V, but any hypothetical rocket.

Roughly half of them, assuming you start from ground level. Possibly less depending on surrounding terrain.

Very funny but don't give up your day job just yet.  Orbital mechanics humor doesn't have a very large audience. 

[Echnaton]

I'm not sure I understand you. By taking off due east from Cape Canaveral, a rocket is following a great circle route. It doesn't maintain this due east orientation, however, any more than a ship or aircraft on a long voyage maintains a constant compass heading all the way to the destination even if it does follow a single great circle route.

Florida is at 28 degrees latitude.....if a rocket flies due East and maintains(or at least tries to hold) that direction.....it is following a path 5 degrees North of the tropic of Cancer. That is not a great circle.

I'm just interested in the orbital mechanics that 'force' the craft into a large circle. Is it a greater gravitational force to its starboard side?

Sorry, I didn't mean to jump in on your question.  It is one I have been wondering about too. 

[cjameshuff]

Florida is at 28 degrees latitude.....if a rocket flies due East and maintains(or at least tries to hold) that direction.....it is following a path 5 degrees North of the tropic of Cancer. That is not a great circle.

I'm just interested in the orbital mechanics that 'force' the craft into a large circle. Is it a greater gravitational force to its starboard side?

Gravitational force is toward the center of the planet, and objects orbit the center of the planet. No matter what direction you start out in, once in freefall, gravity will curve your trajectory around toward the center, resulting in a trajectory within the plane defined by the center of the planet and the initial direction. Every such plane intersects the surface on a great circle.

[ka9q]

Rockets can be launched into orbit in any direction, north, east, south or west, as long as you don't  care what or who it flies over. (This is true for more countries than you might think.)

However, you can't directly reach every orbit this way from every launch site. The lowest inclination (the angle the northbound orbit makes with the equator) that can be directly reached without an expensive dogleg or plane change is equal to the latitude of the launch site.

For example, Cape Canaveral is at 28.5N. Launching due east gives an orbit with a 28.5 degree inclination. Launching due northor south (correcting for Coriolis forces) will give a 90 degree inclination.

Since geostationary orbit has zero inclination, launch sites close to the equator have the advantage. Here you can't beat Sea Launch, which launches their rockets from a converted oil drilling platform that they put in the middle of the Pacific Ocean directly on the equator.

[ka9q]

You should also read up on the concept of a "great circle route". This applies to ships and airplanes as well as rockets.

[Chew]

Florida is at 28 degrees latitude.....if a rocket flies due East and maintains(or at least tries to hold) that direction.....

The guidance system will guide the rocket to follow a great circle path during launch. If you tried to keep it at 28 N until it reached orbital velocity it would be like conducting a constant plane change maneuver and plane changes require a lot of fuel. If you could keep it at 28 N and reach orbital velocity, as soon as the rocket shuts off it will then orbital around the center of mass of the Earth and follow the typical path you see in orbit diagrams.

[Noldi400]

Florida is at 28 degrees latitude.....if a rocket flies due East and maintains(or at least tries to hold) that direction.....

The guidance system will guide the rocket to follow a great circle path during launch. If you tried to keep it at 28 N until it reached orbital velocity it would be like conducting a constant plane change maneuver and plane changes require a lot of fuel. If you could keep it at 28 N and reach orbital velocity, as soon as the rocket shuts off it will then orbital around the center of mass of the Earth and follow the typical path you see in orbit diagrams.

Exactly. Mag40, remember the principle that (absent outside influences) an object in orbit always passes through the point of its last powered maneuver.

[Not Myself]

On any rocket built so far, you'd run out of juice relatively quickly . . .