Road to Space

[Awesomesauce1337]

If one was to build a road that leads all the way up to the altitude of a geostationary orbit, drive up it and jump off would you be in orbit or not?

[kerbiloid]

Totally depends on the final velocity which is totally arbitrary.

[Superfluous J]

I actually did this, in the only environment in which I know it can be done: Astroneer. I fell back to the planet.

Therefore I can guarantee you will fall back to the planet if you try this...

...in Astroneer.

Regarding trying it in reality, and ignoring the impossibility of doing so, then yes if the road is connected to the surface of the Earth and therefore rotates with the Earth, at geostationary altitudes you'll be moving at orbital velocity.

[kerbiloid]

1 minute ago, Superfluous J said:

Regarding trying it in reality, and ignoring the impossibility of doing so, then yes if the road is connected to the surface of the Earth and therefore rotates with the Earth, at geostationary altitudes you'll be moving at orbital velocity.

All roads are attached to the Earth surface, but you move faster or slower than the Earth rotation speed even by car.

Depends on throttle.

[Gargamel]

Moved to S&S. 

[KSK]

Yes. 

This is basically a space elevator. Swap in 'road' for 'cable' in the following description from Wikipedia.

"The horizontal speed, i.e. due to orbital rotation, of each part of the cable increases with altitude, proportional to distance from the center of the Earth, reaching low orbital speed at a point approximately 66 percent of the height between the surface and geostationary orbit, or a height of about 23,400 km. A payload released at this point would go into a highly eccentric elliptical orbit, staying just barely clear from atmospheric reentry, with the periapsis at the same altitude as LEO and the apoapsis at the release height. With increasing release height the orbit would become less eccentric as both periapsis and apoapsis increase, becoming circular at geostationary level. When the payload has reached GEO, the horizontal speed is exactly the speed of a circular orbit at that level, so that if released, it would remain adjacent to that point on the cable. The payload can also continue climbing further up the cable beyond GEO, allowing it to obtain higher speed at jettison. If released from 100,000 km, the payload would have enough speed to reach the asteroid belt."

[kerbiloid]

That's when you are adjusting the speed.

But you don't have to.

[Hannu2]

9 hours ago, Awesomesauce1337 said:

If one was to build a road that leads all the way up to the altitude of a geostationary orbit, drive up it and jump off would you be in orbit or not?

If structure was solid you would be in geostationary orbit.  If structure was higher,  centrifugal force would throw your car (and loose surface material) off from road.  It is same idea than space elevator.

There was a mod in KSP which had celestial body with higher centrifugal force than surface gravity at equator. It is impossible to stay on such place without continuous force or fixing to surface.

[DDE]

7 hours ago, Hannu2 said:

There was a mod in KSP which had celestial body with higher centrifugal force than surface gravity at equator. It is impossible to stay on such place without continuous force or fixing to surface.

It's likely such conditions are achieved on smaller moons or fast-spinning dwarf planets.

[Superfluous J]

16 hours ago, kerbiloid said:

All roads are attached to the Earth surface, but you move faster or slower than the Earth rotation speed even by car.

Depends on throttle.

True. If you can get your car going a good fraction of geostationary orbital speed (3km/s) then sure you may be able to fall back to Earth or reach escape velocity.

I mean we're a civilization able to build a road into space. We probably have pretty good cars.

[kerbiloid]

6 hours ago, Superfluous J said:

We probably have pretty good cars.

And maglev trains.

In vacuum they can reach airplane speed, and maybe even 3 km/s.
(Comparable to the artillery shell speed, but artillery shells aren't suspended, they rub against the barrel.)

[Superfluous J]

39 minutes ago, kerbiloid said:

And maglev trains.

Well the original thought experiment posited driving a car on a road, so I think we need to stick to those.

Unless you define a "car" in such a way to include maglev trains. And a "road" in such a way to include maglev rails.

I mean it worked for tacos and sandwiches...

Edited July 15, 2022 by Superfluous J

[KSK]

1 hour ago, Superfluous J said:

Well the original thought experiment posited driving a car on a road, so I think we need to stick to those.

Unless you define a "car" in such a way to include maglev trains. And a "road" in such a way to include maglev rails.

I mean it worked for tacos and sandwiches...

Trains have restaurant cars, so I'm cool with this.

[kerbiloid]

1 hour ago, Superfluous J said:

a car

I counted boxcars.

[Shpaget]

4 hours ago, KSK said:

Trains have restaurant cars, so I'm cool with this.

A proposal, if I may. Cars with restaurant trains. 

Flexibility of a car to not be restricted to a rail network, but all the luxuries and comfort of a train. Plus, since it's a restaurant train, and not a car, it's necessarily bigger, and bigger is better.

[linuxgurugamer]

Just now, Shpaget said:

A proposal, if I may. Cars with restaurant trains. 

Flexibility of a car to not be restricted to a rail network, but all the luxuries and comfort of a train. Plus, since it's a restaurant train, and not a car, it's necessarily bigger, and bigger is better.

Ever hear of roadtrains?  https://en.wikipedia.org/wiki/Road_train

Problem is power.  Even with the huge engines that trains have, they can only climb very low grades.  Cars are, on the other hand, grossly overpowered for their main function of moving people/things from point A to point B, some of that overpower is used to be able to go up and down hills without too much difficulty

[kerbiloid]

Individual cars move along the roads, not across them.

So, inidividual railroad cars are just a question of necessity.

https://en.wikipedia.org/wiki/Draisine

https://en.wikipedia.org/wiki/Railcar

 

The same with maglev.

[monophonic]

2 hours ago, linuxgurugamer said:

Ever hear of roadtrains?  https://en.wikipedia.org/wiki/Road_train

Problem is power.  Even with the huge engines that trains have, they can only climb very low grades.  Cars are, on the other hand, grossly overpowered for their main function of moving people/things from point A to point B, some of that overpower is used to be able to go up and down hills without too much difficulty

I'll see your road train and raise you a rack railway:

The problem is not power, it is friction. Even the stickiest rubber tires will slip on steep enough a gradient. With more power you'll just burn through them quicker. The answer is a rack and pinion. Friction is not an issue when the force is transmitted from tooth to tooth, against rather than across their surfaces.

[kerbiloid]

1 hour ago, monophonic said:

The problem is not power, it is friction.

That's why maglev.

[linuxgurugamer]

2 hours ago, monophonic said:

I'll see your road train and raise you a rack railway:

The problem is not power, it is friction. Even the stickiest rubber tires will slip on steep enough a gradient. With more power you'll just burn through them quicker. The answer is a rack and pinion. Friction is not an issue when the force is transmitted from tooth to tooth, against rather than across their surfaces.

Actually both.  You are correct re friction, but gradients that steep are only used in rare instances.   So it's still based on power.  The higher the gradient, the more power needed to move the same amount of load