Entering orbit

[Varsi]

So when Leopard/Argo comes to a planet it has engines on and nose forward. And then somehow it gets in orbit by shutting off engines? Or course the same applies to every approach they make in space.

This probably troubles me the most while playing Battletech.

 

[mjbroekman]

Um. That's because you don't want your main engines firing if you want to stay in orbit. You want gravity to do that with the occasional assist from manuevering thrusters. Same with approaches to the jumpship. You don't want your main engines firing for that, you want small thrusters to make the delicate changes to let you connect to the other ship without crashing into it.

The main engines are really used only for getting up to (or slowing down to) a particular speed. Once you are at the desired speed, you can shut off the engines and coast.

With respect to the 'nose forward' part, yeah... the Leopard / Argo should really turn around and fire the engines to slow down to orbital velocity considering the fact that they've been "accelerating" towards the planet (or ship) the whole time...or have they? maybe they've decelerated too much, flip the ship so it's facing the target object and accelerate a little bit with the engines before the "orbital insertion / docking" animation that we see...

Either way, if that's what troubles you most when playing BattleTech, you've got a pretty worry-free game going on

 

[AncientRaig]

Any orbit-establishing burn would happen long before the "orbital entry" cutscene plays. The cutscene is likely showing final adjustments to achieve a stable orbit, and as an easy way to indicate that you are arriving.

 

[Lunatic Pathos]

Everything being relative, for the orbit entry shots, I suppose it is possible that the Argo is actually doing a retrograde burn for orbital insertion but we're viewing it from a camera in a very fast hyperbolic orbit passing the Argo up as it slows...

Really until actual manned flights entering orbit from interplanetary space is photographed and broadcast fairly regularly, the public consciousness just isn't going to understand what's happening if they showed it "correctly" for planet orbit insertion. You could probably show docking correctly though.

 

[TunaSammich]

Any orbit-establishing burn would happen long before the "orbital entry" cutscene plays. The cutscene is likely showing final adjustments to achieve a stable orbit, and as an easy way to indicate that you are arriving.

I like this explanation. I suspect the real reason is because it would be visually jarring to watch the Argo fly "backwards" if you're a filthy casual who doesn't understand orbital mechanics.

 

[Varsi]

Everything being relative, for the orbit entry shots, I suppose it is possible that the Argo is actually doing a retrograde burn for orbital insertion but we're viewing it from a camera in a very fast hyperbolic orbit passing the Argo up as it slows...

Really until actual manned flights entering orbit from interplanetary space is photographed and broadcast fairly regularly, the public consciousness just isn't going to understand what's happening if they showed it "correctly" for planet orbit insertion. You could probably show docking correctly though.

Would be about time we start showing it correctly tho. It's not like spaceX rockets come back to landing pad nose first and just stop engines before landing softly.

 

[mjbroekman]

Would be about time we start showing it correctly tho. It's not like spaceX rockets come back to landing pad nose first and just stop engines before landing softly.

Absolutely, but SpaceX rockets landing on Earth are having to counteract gravity in order to stop. Rockets in space do not need to slow down to 0 kph. If they did, gravity would take over and slam them into the planet.

In order to stay in orbit (such as the Argo approaching a planet), they need to accelerate to orbital velocity. Around Earth, you need around 7.8 kilometers per second in order to maintain low earth orbit. If you're not travelling at that speed, you need to burn your main (orbital) engines to get there and once you have reached that speed you use maneuvering thrusters to make minute changes to your orientation in orbit.

In order to "come to a stop" in relation to other object in space, such as a satellite or JumpShip, you need to match velocities. Again, this is the purpose of main (orbital) engines, not thrusters. Thrusters would be used for nudging the ships to the point that a mechanical system can catch them and pull them together. In space, you almost never want to actually bump into another ship because the chance of damage is too great. You almost always want to come to rest relative to each other and then one of the ships "reaches" out (like with the robotic arm on the Space Shuttle or ISS) and grabs the other ship to pull it in with even more delicacy than thrusters could achieve.

In short, when landing, yes... you fire engines to come to stop if you aren't aerodynamically able to slow down (such as the Space Shuttle, which came in for landings WITHOUT using its engines and simply bled off speed with aerodynamic braking). When in space, you let momentum carry you to your destination...engines are simply for changing your speed, not for actually pushing you all the way there.

If anything can be quibbled about in the animations it is:
1. That the Argo / Leopard show their engines firing while travelling to / from the JumpShip.

Beyond that, you can hand-wave that the "match (orbital) velocity" burns happen in the transition from where we are "travelling to" the destination and actually docking / orbiting.

 

[Varsi]

Absolutely, but SpaceX rockets landing on Earth are having to counteract gravity in order to stop. Rockets in space do not need to slow down to 0 kph. If they did, gravity would take over and slam them into the planet.

In order to stay in orbit (such as the Argo approaching a planet), they need to accelerate to orbital velocity. Around Earth, you need around 7.8 kilometers per second in order to maintain low earth orbit. If you're not travelling at that speed, you need to burn your main (orbital) engines to get there and once you have reached that speed you use maneuvering thrusters to make minute changes to your orientation in orbit.

In order to "come to a stop" in relation to other object in space, such as a satellite or JumpShip, you need to match velocities. Again, this is the purpose of main (orbital) engines, not thrusters. Thrusters would be used for nudging the ships to the point that a mechanical system can catch them and pull them together. In space, you almost never want to actually bump into another ship because the chance of damage is too great. You almost always want to come to rest relative to each other and then one of the ships "reaches" out (like with the robotic arm on the Space Shuttle or ISS) and grabs the other ship to pull it in with even more delicacy than thrusters could achieve.

In short, when landing, yes... you fire engines to come to stop if you aren't aerodynamically able to slow down (such as the Space Shuttle, which came in for landings WITHOUT using its engines and simply bled off speed with aerodynamic braking). When in space, you let momentum carry you to your destination...engines are simply for changing your speed, not for actually pushing you all the way there.

If anything can be quibbled about in the animations it is:
1. That the Argo / Leopard show their engines firing while travelling to / from the JumpShip.

Beyond that, you can hand-wave that the "match (orbital) velocity" burns happen in the transition from where we are "travelling to" the destination and actually docking / orbiting.

You may want to reconsider the the orbit part. Sure if you are falling from orbit you'll need to accelerate to stay in orbit but when you are coming in at interplanetary speeds you will definitely need to slow down or you'll just fly by the planet.

The matching speed with a jumpship part is correct but again you would be coming from some direction and you would need to slow down in relation to the jumpship to match speed with it.

Kerbal Space Program, while simplified, teaches a lot about orbital mechanics. Childer of a Dead Earth was another one with fun maneuvers to intercept targets.

Edit:
And adding to that "When in space, you let momentum carry you to your destination...engines are simply for changing your speed, not for actually pushing you all the way there.". In Battletech the ships do the same thing they do in The Expanse books/series. They maintain constant acceleration (1g for comfort) the whole way. Half the trip is accelerating and then the ship is flipped around and decelerate to not fly past the target.

 

[mjbroekman]

You may want to reconsider the the orbit part. Sure if you are falling from orbit you'll need to accelerate to stay in orbit but when you are coming in at interplanetary speeds you will definitely need to slow down or you'll just fly by the planet.

The matching speed with a jumpship part is correct but again you would be coming from some direction and you would need to slow down in relation to the jumpship to match speed with it.

Kerbal Space Program, while simplified, teaches a lot about orbital mechanics. Childer of a Dead Earth was another one with fun maneuvers to intercept targets.

Absolutely. You definitely need to counter your forward velocity went entering orbit or matching relative speeds. However, to say that it's unrealistic for them to cut main engines on entering orbit or on jumpship approach is equally incorrect. "Interplanetary speeds" is anything sufficient to get out of our current gravity well. When leaving from a standstill (jumpship), that is a relatively small velocity. There is no need to be under constant acceleration for the entire journey. It's a waste of fuel and incredibly inefficient. So, if anything, I'm a little bugged by the "travel" screen showing the engines firing when moving from planet to jumpship and back. Maybe I'm misunderstanding the intensity, but "bothered" to me implies something immersion-breaking...which I don't find it to be.

But to each their own. Would it be nice to have the art/animation to show the flip? Yes. Is it necessary? Nah.

 

[Varsi]

Absolutely. You definitely need to counter your forward velocity went entering orbit or matching relative speeds. However, to say that it's unrealistic for them to cut main engines on entering orbit or on jumpship approach is equally incorrect. "Interplanetary speeds" is anything sufficient to get out of our current gravity well. When leaving from a standstill (jumpship), that is a relatively small velocity. There is no need to be under constant acceleration for the entire journey. It's a waste of fuel and incredibly inefficient. So, if anything, I'm a little bugged by the "travel" screen showing the engines firing when moving from planet to jumpship and back. Maybe I'm misunderstanding the intensity, but "bothered" to me implies something immersion-breaking...which I don't find it to be.

But to each their own. Would it be nice to have the art/animation to show the flip? Yes. Is it necessary? Nah.

Well yeah. They obviously need to shut the engines once in preferred orbit or after matching speed with the target. From the animations it just seems they slow down by shutting the engines.

The constant acceleration is used to cut the travel time from months to a week or two. Not feasible with chemical rockets obviously but here our ship works with magic (fusion reactor and some stuff to accelerate a lot for thrust?) so it's not an issue.
And yea, this is definitely a small thing. Fortunately I haven't been affected by any of the real issues people are having and just get the slow down after very long sessions so I actually need to look for issues.

 

[Kellcat]

I think the complaint wasn’t that they shut down their engines, but that they’re facing the wrong direction when they’re firing their engines. After hundreds of hours of Kerbal Space Program, it continues to be pretty jarring to me, too.

 

[tobias.mb]

Well, technically the Argo could be on an intercept course, where it lets the planet "catch up" from behind, so to speek.
In this case it would be necessary to fire the engines once the planet has passed, to keep up with it and enter a stable orbit.

 

[Max_Killjoy]

What's happening is that the people doing the video are thinking about airplanes and ships in a friction environment, and not thinking about how things work in space.

"Shut engines off = stopping".

Ugh.