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[Sean Mirrsen]

It's really much less player-time-intensive to use bi-elliptic transfers than waiting for windows for true Hohmann transfers.

A true Hohmann transfer requires that you use a very specific point in your orbit to arrive at the target, and use it at a very specific time to actually arrive at your target. Whereas with a bi-elliptic transfer, if you are significantly in front of, or behind, the target you want, you can tune the time you take to arrive at the target by simply extending or contracting the apoapsis of your bi-elliptic transfer's midpoint.

[Facekillz058]

I'm pretty sure that it's going to be impossible for me to get anymore science without Struts and Fuel Lines, D:

[Girlinhat]

What'll you do for power?

I'll admit this part slipped my mind on this first try...for now just hoping the Mechjeb unit uses little power.

Lining up the boosters properly is also going to be a pain.

Um....MECHJEB. I'm pretty sure it has autodocking.

Mechjeb does not do any alignment when docking. Default values will have it slamming vehicle against vehicle. Things will bounce around a bit. It'll dock but it's a wild ride and things will be askew.

Dunno what version of Mechjeb you're using, but when I tried it ran extremely well for auto-docking.  Just use [ and ] to swap to the docking target and 'face away from target' (assuming docking port is on backside of rocket) and then swap to the ship moving in to dock, and select the port and run it.

[mainiac]

How do I figure out what altitude to make my gravity turns at during launch to LKO?  I have the impression that a small craft should do it around 6 km while a larger one should do it later but haven't found any information on how much later.

[BigD145]

What'll you do for power?

I'll admit this part slipped my mind on this first try...for now just hoping the Mechjeb unit uses little power.

Lining up the boosters properly is also going to be a pain.

Um....MECHJEB. I'm pretty sure it has autodocking.

Mechjeb does not do any alignment when docking. Default values will have it slamming vehicle against vehicle. Things will bounce around a bit. It'll dock but it's a wild ride and things will be askew.

Dunno what version of Mechjeb you're using, but when I tried it ran extremely well for auto-docking.  Just use [ and ] to swap to the docking target and 'face away from target' (assuming docking port is on backside of rocket) and then swap to the ship moving in to dock, and select the port and run it.

I am using the latest version. Crafts will dock but mechjeb doesn't care about final alignment when docked.

[miauw62]

IIRC, Mechjeb should list the phase angles somewhere.

[Siquo]

It's really much less player-time-intensive to use bi-elliptic transfers than waiting for windows for true Hohmann transfers.

A true Hohmann transfer requires that you use a very specific point in your orbit to arrive at the target, and use it at a very specific time to actually arrive at your target. Whereas with a bi-elliptic transfer, if you are significantly in front of, or behind, the target you want, you can tune the time you take to arrive at the target by simply extending or contracting the apoapsis of your bi-elliptic transfer's midpoint.

That is actually not a bad idea... I might try that move some time. But the time-compression means that player-time wise it's not that much of an improvement. Using a Hohmann transfer one ideally only needs two burn-moments, where bi-elliptic needs 3, and getting your craft in a specific location in orbit is just a manner of pressing fast-forward a few times.

[ank]

That's just an orbital transfer.  A Homman Transfer is going to a specific orbit at a specific time to intercept another body.  It's an exercise in timing and very mathy to get right, but somewhat possible to eyeball it when you've been playing a few... weeks...

Nope, orbital transfer = Hohman transfer

Wikipedia:
"In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits of different altitudes, in the same plane."

[Sean Mirrsen]

It's really much less player-time-intensive to use bi-elliptic transfers than waiting for windows for true Hohmann transfers.

A true Hohmann transfer requires that you use a very specific point in your orbit to arrive at the target, and use it at a very specific time to actually arrive at your target. Whereas with a bi-elliptic transfer, if you are significantly in front of, or behind, the target you want, you can tune the time you take to arrive at the target by simply extending or contracting the apoapsis of your bi-elliptic transfer's midpoint.

That is actually not a bad idea... I might try that move some time. But the time-compression means that player-time wise it's not that much of an improvement. Using a Hohmann transfer one ideally only needs two burn-moments, where bi-elliptic needs 3, and getting your craft in a specific location in orbit is just a manner of pressing fast-forward a few times.

True, assuming you're in interplanetary space or high enough above something that you can timewarp with impunity. But if you want to start at a specific time, for instance to maximize gain from the Oberth effect or something, it might be useful. A neat little trick to know, in any case. ^_^

[Girlinhat]

That's just an orbital transfer.  A Homman Transfer is going to a specific orbit at a specific time to intercept another body.  It's an exercise in timing and very mathy to get right, but somewhat possible to eyeball it when you've been playing a few... weeks...

Nope, orbital transfer = Hohman transfer

Wikipedia:
"In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits of different altitudes, in the same plane."

What would NOT be a Homman then?

[Sean Mirrsen]

An orbital transfer to an orbit with a different anything, except peri/apoapsis. A Hohmann transfer is two "straight ahead" burns. No midcourse corrections, no inclination change, no eccentricity change.

[sluissa]

Except that outside of a game with nice clean math, that never happens.

[ank]

That's just an orbital transfer.  A Homman Transfer is going to a specific orbit at a specific time to intercept another body.  It's an exercise in timing and very mathy to get right, but somewhat possible to eyeball it when you've been playing a few... weeks...

Nope, orbital transfer = Hohman transfer

Wikipedia:
"In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits of different altitudes, in the same plane."

What would NOT be a Homman then?

Like the direct transfer method where you basically just burn towards your target, then burn retrograde halfway, also known as Stupid Transfer... I can't recall the actual name, but someone brought it up in this thread months ago, it's from a sci-fi novel where their ship basically had infinite weightless fuel... so yeah...

Also as Sean said.

Hohmann transfers are the true bread and butter of space travel.

Also, this is not aimed at you, but I've seen a lot of people spelling it Homman, but it's Hohmann.
(I know I misspelled it Hohman before)

[BigD145]

Oh. Newer mechjeb. The pod is back. Now you can be watched. It's also capable of reaching almost 20000 m up on Kerbin all by itself. Top tier experimental research.

[Krevsin]

That's just an orbital transfer.  A Homman Transfer is going to a specific orbit at a specific time to intercept another body.  It's an exercise in timing and very mathy to get right, but somewhat possible to eyeball it when you've been playing a few... weeks...

Nope, orbital transfer = Hohman transfer

Wikipedia:
"In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits of different altitudes, in the same plane."

What would NOT be a Homman then?

Like the direct transfer method where you basically just burn towards your target, then burn retrograde halfway, also known as Stupid Transfer... I can't recall the actual name, but someone brought it up in this thread months ago, it's from a sci-fi novel where their ship basically had infinite weightless fuel... so yeah...

It's not all that stupid an idea. I think it's called a "Brachistochrone trajectory".

Also, it's not that the fuel is crazy light, it's that the engine is incredibly efficient at burning it, with the Isp in tens of thousands and can generate quite a lot of power.

It's an entirely plausible concept and incredibly viable in various midfuture hard sci-fi settings (like most of Heinlein's work), it's just that right now we cannot create anything as incredibly efficient as such an engine, so we rely on good ol' Hohmann, our lord and saviour of Orbital Mechanics, to get anywhere..


Although, there is ONE way with which we could achieve such a trajectory with current technology. Or something very much like one.