Is this an orbit or no? According to KSP.

[Zombie Jesus]

So I attempted to put a craft into kerbins orbit to complete the orbit kerbin task. My Pe is 50,625 and my Ae is 132,450.

I didn't get a completion on the task. The craft has orbited kerbin three times with no change in the Pe or Ae.

Is the game not counting this as an orbit because technically the Pe is inside the atmo's, even though theroretically you should be able to orbit at 10,000m (with an insane ammount of speed).

[HoloYolo]

Originally posted by ZombieJesus:

So I attempted to put a craft into kerbins orbit to complete the orbit kerbin task. My Pe is 50,625 and my Ae is 132,450.

I didn't get a completion on the task. The craft has orbited kerbin three times with no change in the Pe or Ae.

Is the game not counting this as an orbit because technically the Pe is inside the atmo's, even though theroretically you should be able to orbit at 10,000m (with an insane ammount of speed).

Pe needs to be 70km and btw you can't orbit at 10km it's waaaaaaaaaaaaaaaaaaaaaaaaay too low.

[Bamwich]

Probably. Just burn a little at your Apo and get your Peri above 70k.

[Zombie Jesus]

[/quote]Pe needs to be 70km and btw you can't orbit at 10km it's waaaaaaaaaaaaaaaaaaaaaaaaay too low. [/quote]

In theory it is possible (under the right conditions i.e. no mountians to get in the way, sleek enough to avoid too much drag, etc) that you could orbit at 10,000m, I'll have to source it for you later. Orbiting is just falling fast enough at the right angle to avoid a collision and make it past the object your orbiting.

Thanks though guys, i figured it was a game mechanic to not register it as an orbit. I'm out of fuel but I have a parachute, I'm wondering if I pop it coming out of my Pe if it'll create enough drag to eventually pull me out of orbit,

[lagrangewei]

the reason it is not an orbit is drag which means anything flying on that path would eventually slow down. and if you have "enough speed" you will only be shooting up your Ae, like a person throwing a ball into the sky, it would only fall. orbiting is not about speed, its about horizontal speed so you would be traveling in the wrong direction if you have enough speed but not enough Pe.

[dwringer]

Who doesn't love playing minimize-the-munar-orbit-altitude-above-ground-level game, though!

[Zombie Jesus]

Originally posted by lagrangewei:

the reason it is not an orbit is drag which means anything flying on that path would eventually slow down. and if you have "enough speed" you will only be shooting up your Ae, like a person throwing a ball into the sky, it would only fall. orbiting is not about speed, its about horizontal speed so you would be traveling in the wrong direction if you have enough speed but not enough Pe.

First your kinda right but not really.

Orbiting is exactly like throwing a ball up into the sky when the ball reaches the apex (the Ae for an orbit) it begins falling again towards the ground (or the object being orbited). The difference is the ball because it lacks tangential velocity is headed straight for the center of mass of the object where in an orbit the tangential velocity causes the "ball" to miss the object being orbited and head towards its Pe to repeat the process in the oposite direction.

You say its not an orbit because drag will slow the "ball" down and cause it to fall towards the center of mass of the object being orbited, this is not correct because you are forgeting that the object is "falling" at a great speed and as it approaches the Pe is it gaining more and more speed. Drag will reduce this speed but it is possible for the "ball" to overcome the drag (also drag could be reduced through aerodynamic designs) and maintain its orbit.

Again I stress it is Theory and not practical. The designs would be insanley costly, time consuming, and insanely hard to make it happen right, also it wouldn't serve any practical purpose, not even for reasearch as the speeds would be too great for most instruments to function properly or gather enough data.

But thats not what this post is about. I realize looking back that my topic subject line was misleading. I did not mean to ask if this fits the definition of an orbit, I know it does. I meant does the game KSP reconize it as an orbit or if the devs programed it to ignore any orbits below 70k, which we know now to be true.

As a summary an orbit can be achieved at any altitude if there is enough tangential velocity, including what is needed to overcome drag, again theorectialy(sp?) possible.

For any specific combination of height above the center of gravity and mass of the planet, there is one specific velocity (unaffected by the mass of the object, which is assumed to be very small relative to the Earth's mass) that produces a circular orbit.

[Zombie Jesus]

Originally posted by dwringer:

Who doesn't love playing minimize-the-munar-orbit-altitude-above-ground-level game, though!

I was able to make a manuever node off of one of my launches that would of had my Pe at ~1050m but I screwed up the burn, I only had seconds to aling the nose around 260 degrees by 80 degrees and conduct a 32 second burn, I couldnt get the nose to hold in the right spot and used up the fuel trying to manuever.

[Empiro]

By orbit, the game means stable orbit. While it's true that if you're just brushing the atmosphere at 50km, you have enough energy to escape the atmosphere, the fact is that you're losing energy every time you enter the atmosphere, and it won't take that many orbits before you lose so much that you'll fall back into Kerbin.

Keep your periapsis above 70km, and you'll never fall back down.

[lagrangewei]

Originally posted by ZombieJesus:

You say its not an orbit because drag will slow the "ball" down and cause it to fall towards the center of mass of the object being orbited, this is not correct because you are forgeting that the object is "falling" at a great speed and as it approaches the Pe is it gaining more and more speed. Drag will reduce this speed but it is possible for the "ball" to overcome the drag (also drag could be reduced through aerodynamic designs) and maintain its orbit. .

I did not forget. if you don't believe it then try it. the ball will hit terminal velocity thus BURNING UP all the excess speed. you cannot retain that speed. seriously you are arguing like perpetual motion machine is real when it is not. aerobraking is a well understood mechanic and if you don't wish to concede on that then prove it.

your theory is all mess up with little understanding of physic.

[Jim]

I agree with Empiro. Although it does not explicitly state it, when the game says an orbit is required, it really means a sustainable orbit (something that won't eventually collapse on itself).

[dwringer]

Originally posted by lagrangewei:

I did not forget. if you don't believe it then try it. the ball will hit terminal velocity thus BURNING UP all the excess speed. you cannot retain that speed. seriously you are arguing like perpetual motion machine is real when it is not. aerobraking is a well understood mechanic and if you don't wish to concede on that then prove it.

your theory is all mess up with little understanding of physic.

Haha, that was more my reaction but I couldn't fully understand his theory in the first place :P

[lagrangewei]

to answer what is really being ask. KSP does not predict trajectory change from atmospheric drag, this is why the trajectory only changes as the ship hit the atmosphere, the game is not coded to predict this and so you would be correct in assuming the game does not consider anything under 70km as an orbit.

[Fishezzz]

your PE must be above 70.000 m and the orbit needs to be circular

[Rene]

Originally posted by emiel.demeestere:

your PE must be above 70.000 m

Yes.

and the orbit needs to be circular

No such restriction applies.

Originally posted by ZombieJesus:

As a summary an orbit can be achieved at any altitude if there is enough tangential velocity, including what is needed to overcome drag, again theorectialy(sp?) possible.

Well orbit would (in the real world) mean that you can keep roughly the same orbital parameters (apoapsis and periapsis the main ones) without propulsion. If you're constantly boosting, well, you're flying, not orbiting.

[Bart-MasterZ]

Indeed the PE must be above 70.000 m for the game to list it as a stable orbit. In KSP you can however indefinitely keep orbiting as long as your PE is above 24.000 m and you are not controlling the vessel (i.e. it is not the active vessel, nor within 2.4 km of the active vessel).