What do you count as a stage?

[FishInferno]

So the other day, me and my friend got into a debate as to wether the space shuttle was 2 stage or 3 stage. He said 3 stage: the boosters, orbiter, and ET. I said 2 stage, boosters an orbiter. I normally don't count boosters as a stage, but since the space shuttle is different I do count them. I don't found the ET because it doesn't do anything, it is more a part of the "second" stage (orbiter) to me. But it got me thinking: What do you count as a stage? Do you count boosters and dropped tanks, or just the main stack?

In other words, wat is your definition I a stage? Not just in the shuttle, but in general?

Edited June 23, 2014 by FishInferno

[TheCanadianVendingMachine]

The Space Shuttle has 3 stages -

SRB Seperation

External Tank Seperation

Orbiter Seperation

So, that is what I consider as a stage

[FishInferno]

The reason I don't could the ET is that it doesn't have any engines or anything, it is just te fuel tanks for the second stage.

Orbiter separation? Waaah? We already had ET sep.

[Taki117]

I consider a stage any time I press the space bar. The Shuttle then is 3 stages.

Stage 1: SRB Sep

Stage 2: OMS ignition (It does ignite on liftoff)

Stage 3: ET Sep

[SkyRender]

Anything that gets dropped counts as a stage, including the final vehicle that returns to the planet ("stage 0" since it generally has no propulsion of its own). Technically a vehicle with multiple engine-firing phases that doesn't drop anything does have multiple stages, but practically speaking it does not since nothing ever gets dropped and what goes up into space is exactly what comes back from space.

[Jouni]

Every time you drop fuel tanks and/or engines, you get one more stage. By this definition, the Space Shuttle had three stages, but it could have reached orbit with just two stages.

[Sandworm]

Dropping anything counts is staging, just maybe not a full stage. A few rockets, such as the early Atlas boosters, dropped engines but not the tanks that fed them. This is sometimes called a "half stage". If dropping an engine is a half stage, then the shuttle dropping a tank would be the other half. So shuttle was a 2.5 stage rocket in that the engines were never dropped.

[Whackjob]

Stage 7- Throttle to full, decouple all seperatrons, activate all chutes

Stage 6- Detonate crew capsule

Stage 5- Detonate solid boosters

Stage 4- Detonate science package

Stage 3- Detonate liquid boosters

Stage 2- Detonate RCS storage

Stage 1- Detonate launch clamps

Stage 0- Bonus stage, detonate coffee pot in control tower

[cantab]

For me a "stage" implies that both engines and tanks are dropped. If you just drop tanks, they're drop tanks, though the dropping itself might be called a "staging event". If you just drop engines, well I guess that's the stage-and-a-half kind of stuff that's been mentioned.

So I suppose the Space Shuttle would be two stages: SRBs and Orbiter, with the orbiter dropping its drop tank just before circularising. (Though I don't think it was ever done, the Shuttle could have taken the ET into orbit if desired.)

[allmhuran]

The ambiguities of what counts as a stage have been well highlighted by all of the posts in this thread. I would probably say that any part (of number of parts separated at once) of the vehicle which is independent and has its own engine is a stage, so "drop tanks" are not stages (which is nice, otherwise a lot of jets would be classified as "multistage" vehicles), and the shuttle would be a 2 stage vehicle.

However, one could always take the more philosophical position that the ambiguity raised by contradictory yet useful definitions makes the concept of the "one-true-stage" kinda pointless, and instead use a functional definition: whatever you have put into a separate stage in your KSP staging list is a stage.

[Tortoise]

Anything that has a decoupler attached to it.

[Red Iron Crown]

Any time you jettison a part or parts, I consider that a stage. Igniting different engines without dropping anything? Not a stage, though it might be in the staging list in KSP.

Technically I consider an aircraft with drop tanks to be multistage, but that's a semantic thing. I generally don't think of aircraft in terms of stages.

[GoSlash27]

I'm with Taki. If I hit the space bar and something falls off, it's a stage.

[Moss]

I was under the impression that missions were divided into stages regardless of bits falling off the craft. A stage could in theory consist of the craft simple making an injection or insertion burn.

[Red Iron Crown]

I was under the impression that missions were divided into stages regardless of bits falling off the craft. A stage could in theory consist of the craft simple making an injection or insertion burn.

I don't think "stage" is the proper term for that, in rocketry and spaceflight "stage" has a more specific meaning than in general use.

[Moss]

That's what I meant. From looking at the Mars direct proposed profile, I recall that the bit where, by reeling the habitat out from the engine module on a cable, they create artificial gravity for the crew counted as a stage.

[Red Iron Crown]

I wouldn't consider it a stage if it's not discarding something. Reconfiguring the ship to create centrifugal "gravity" wouldn't count, to my mind. But maybe the Mars direct people think differently, or the description you read was written by a PR person rather than a rocket scientist.

[FishInferno]

I personally would not count that as a stage, because you are not simply discarding the engine module. You are still using it.

Ps. Thanks whoever moved this:) sorry it was in the wrong place:P

[WJDubs]

I say this: Stage 1, Ignition of engines, Stage 2, SRB decoupling, Stage 3, ET Decoupling.

Just my thought.

[R0cketC0der]

I consider the Space Shuttle a 2 stage vehicle:

First stage: ignition of boosters and main engines

Second stage: decoupling of the boosters

The external tank separation doesn't count as a stage to me because it only contains fuel and no engines and the OMS ignition doesn't count as a stage to me because they are on the same part of the vehicle as the main engines.

[FishInferno]

Isn't count engine ignition as a stage. I count stages as more of the object rather than the action. Like I count the boosters instead of booster seperation. I count the orbiter as a stage, the stage that makes it to orbit.

[Nuke]

my definition of a stage is whenever the configuration of the vehicle changes significantly. stage one you turn on the engines, stage two you drop some boosters, stage 3 you drop some tankage. all very significant changes to the configuration.

Edited June 23, 2014 by Nuke