What is payload?

[KerikBalm]

No it's not in fact.

Mass of payload: Mp = 50 t.

Mass of rocket (mass of lifter): Ml = 50 t.

Whole mass: M = Mp + Ml = 100 t.

50 t / 100 t = .5 = 50%

Except what he said would have been:

Mass of payload: Mp = 50 t.

Mass of Lifter: Ml = 50 t.

50/50 = 100% -> which is the wrong way to calculate it. You did calculate it the right way.

I guess that means your math/engineering skills are better than your English skills

Payload fraction of 100% means you have no lifter and still get your payload in orbit, possibly with Hyperedit.

Exactly, which is why you divide payload mass by total mass, not payload mass by non-payload mass like he said.

[OhioBob]

No it's not in fact.

Mass of payload: Mp = 50 t.

Mass of rocket (mass of lifter): Ml = 50 t.

Whole mass: M = Mp + Ml = 100 t.

50 t / 100 t = .5 = 50%

Payload fraction of 100% means you have no lifter and still get your payload in orbit, possibly with Hyperedit.

Champ was replying to this:

The weight of the payload, divided by the weight of the non-payload part of the rocket, is your payload fraction.

If a 50ton rocket can somehow put a 50ton payload into orbit, then that rocket has a payload fraction of 50%.

According to that definition, the payload fraction is

50 t / 50 t = 1 = 100%

But that is incorrect. We divide by the total mass including payload,

50 t / 100 t = .5 = 50%

Edited September 15, 2015 by OhioBob

[Champ]

That's what i said : total mass = 100t, payload mass = 50t => payload fraction = 50/100= 50%.

If you try with MailletC's defintion, (payload mass divided by non-payload mass), you get 50/50=100%

Edit : Ninja'd. Twice !

[vixr]

When the hammer is dropped, the outcome is a bullet...everything else is delivery vehicle.

[nothingSpecial]

Except what he said would have been:

Mass of payload: Mp = 50 t.

Mass of Lifter: Ml = 50 t.

50/50 = 100% -> which is the wrong way to calculate it. You did calculate it the right way.

I guess that means your math/engineering skills are better than your English skills

Exactly, which is why you divide payload mass by total mass, not payload mass by non-payload mass like he said.

Champ was replying to this:

According to that definition, the payload fraction is

50 t / 50 t = 1 = 100%

But that is incorrect. We divide by the total mass including payload,

50 t / 100 t = .5 = 50%

That's what i said : total mass = 100t, payload mass = 50t => payload fraction = 50/100= 50%.

If you try with MailletC's defintion, (payload mass divided by non-payload mass), you get 50/50=100%

Edit : Ninja'd. Twice !

Oh I see now that he used "non payload", sorry.

[cicatrix]

A sandalone term 'payload' is meaningless. It is always connected with the vehicle. Generally, it is the maximum mass a vehicle is capable of delivering to (put here your destination).

So, when it comes to rockets, the payload fraction is the wet full mass M1 of the whole craft (including the payload) standing still on the launchpad and the final maximum possible mass of the same craft in the orbit (LKO, KSO, etc) - M2. M2/M1 *IS* the payload fraction.

[Guest]

Grey area. The payload could be the structure of the 'payload' stage, not counting the fuel it contained on the pad.

Most certainly is a grey area. For instance, I consider the Shuttle part of the STS to be "payload" since it arrives in orbit. Unfortunately that means that the Shuttle was basically dead weight, but it does put the STS into the "heavy lifter" category since total mass in orbit was around 100 tons. Energia/Buran has a much better defined distinction between payload and lifter.

[moogoob]

Fun thread. Payload is relative. My transfer stage + interplanetary probe are my launcher's payload, and the probe is the transfer stage's payload. Makes sense, no?

[nothingSpecial]

Fun thread. Payload is relative. My transfer stage + interplanetary probe are my launcher's payload, and the probe is the transfer stage's payload. Makes sense, no?

Of course, until you face sentences like "rockets usually have around 20% payload fraction and spaceplanes usually have 30% or more" and wonder what exactly is considered to be payload in such different launch designs.

[Guest]

Of course, until you face sentences like "rockets usually have around 20% payload fraction and spaceplanes usually have 30% or more" and wonder what exactly is considered to be payload in such different launch designs.

On Earth LEO is considered to be between 160km and 2000km so I'd say Kerbin's "LKO" is roughly 75km to 500km, maybe? Payload to LEO/LKO is the mass fraction in a stable orbit with periapsis/apoapsis between those values. The "gold standard" for Kerbin, IMO, is the mass fraction in a stable orbit with an apoapsis and periapsis above 75km.

[mhoram]

Of course, until you face sentences like "rockets usually have around 20% payload fraction and spaceplanes usually have 30% or more" and wonder what exactly is considered to be payload in such different launch designs.

It is just the same with TWR, which usually is taken in the meaning "TWR at Kerbins sealevel".

Usually the wording "payload fraction" is used in context of "payload fraction from the launchpad/runway to Low Kerbin Orbit".

[Guest]

Weight of the payload divided by the weight of the whole craft.

Your definition, applied to your exemple, gives a payload fraction of 100%.

Complain about me mistyping something why don't you. The example I gave is correct, even if the definition was not.

[nothingSpecial]

On Earth LEO is considered to be between 160km and 2000km so I'd say Kerbin's "LKO" is roughly 75km to 500km, maybe? Payload to LEO/LKO is the mass fraction in a stable orbit with periapsis/apoapsis between those values. The "gold standard" for Kerbin, IMO, is the mass fraction in a stable orbit with an apoapsis and periapsis above 75km.

Well, thanks for reference.

By the way, to be honest, after 1.0.4 I usually find myself having hard time circularizing anywhere lower than 80km and generally aim for 105 km

- - - Updated - - -

It is just the same with TWR, which usually is taken in the meaning "TWR at Kerbins sealevel".

Usually the wording "payload fraction" is used in context of "payload fraction from the launchpad/runway to Low Kerbin Orbit".

It still striked to me as non-obvious, especially when taking into account crew. asparagus-assisting orbital core or spaceplanes that are used not only for delievering payload to LKO and returning back.

[Guest]

By the way, to be honest, after 1.0.4 I usually find myself having hard time circularizing anywhere lower than 80km and generally aim for 105 km

Your gravity turn is too steep, tilt over earlier. in 1.0.4 I start my turn at around 75m/s and follow the prograde marker. This works for a launch TWR of around 1.3~1.4 and an upper stage TWR of at least 0.8.

[TimePeriod]

I only see the final component into LKO as the payload.

[nothingSpecial]

Your gravity turn is too steep, tilt over earlier. in 1.0.4 I start my turn at around 75m/s and follow the prograde marker. This works for a launch TWR of around 1.3~1.4 and an upper stage TWR of at least 0.8.

I suppose that's the question of TWR and control surface in my case. I tend to overshoot (hardly get TWR less than 1.8 at start) and usually have basic fins at the first stage, and rarely can make my AoA higher than 5 degrees without consequences. But bigger fins just don't look good...

[Guest]

I suppose that's the question of TWR and control surface in my case. I tend to overshoot (hardly get TWR less than 1.8 at start) and usually have basic fins at the first stage, and rarely can make my AoA higher than 5 degrees without consequences. But bigger fins just don't look good...

Off-topic, but once you hit the third atmosphere band you have much more freedom in how you adjust your turn; you can probably go for a nearly horizontal burn if the launch TWR is that high, since the lower stage launch is so steep. I call that a "pop-up" style launch and it works pretty well with high-TWR SRM lifters with anemic upper stages (also had a lot of success with that sort of launch using my Angara 5 replica, would probably work well with a Saturn V as well).

[Laie]

"Payload" is one of those terms that mean exactly what the speaker has in mind. As Starhawk said, the lander is the payload of the transfer stage, the transfer stage is the payload of the lifter, and so on. Given that most missions have a russian doll aspect, it's usually not difficult to figure out the given payload in a particular context.

Of course, until you face sentences like "rockets usually have around 20% payload fraction and spaceplanes usually have 30% or more" and wonder what exactly is considered to be payload in such different launch designs.

In that case, I always assume "payload to LKO".

I suppose that's the question of TWR and control surface in my case. I tend to overshoot (hardly get TWR less than 1.8 at start) and usually have basic fins at the first stage, and rarely can make my AoA higher than 5 degrees without consequences. But bigger fins just don't look good...

Such things can be very efficient, but you need to fly a very shallow ascent. I've seen that approach and tried it myself in the context of one of the more recent challenges. Stock Payload Fraction perhaps? Starting TWR=2 and tipping the vessel 5-10° in VAB, I could get into orbit at very little dV and with minimal command input. The aerodynamic effects looked scary, though.

[J.Random]

Pft. Easy. Payload is what you're paying for. Literally. If it's a LEO payload, it should reach LEO without using (or not having) its own propulsion means. Spaceplane is not a payload, unless it sits as a deadweight on a rocket. Saturn-V third stage (which was also a TLI stage) was not technically part of LEO payload, because it had to do a burn to reach its designated LEO. Breeze-M may be at least partially covered by payload fairings, but it isn't payload, either for LEO or GTO/GSO. If you're paying for transfer to GTO but intend to stay on GSO, the mass you've paid for includes your own propulsion system, and it's part of the GTO payload.

[mikegarrison]

Payload is the load that pays for the mission. Very simple, except for when it's complicated.

It's most clear in a commercial application. In an airline, for instance, payload is the passengers, their luggage, and any revenue cargo. The airplane, the flight crew, etc. are not payload.

But with something like Apollo 11 the whole purpose of the mission was to land some people on the moon. The astronauts were payload, really. (Well, maybe not Collins.)

And payload can depend on whether you are planning the whole mission or just working on the launch. If you are a launch engineer, the "payload" of a shuttle launch was the orbiter and everything in it. But if you were the mission planner, the "payload" was only whatever was in the cargo bay. And if you were a satcom company, the "payload" was just the part of the satellite that handled the communications. Everything else (the shuttle, the crew, the upper stage that boosted the satellite to its final orbit, and even the parts of the satellite intended for stationkeeping and the like) were not "payload".

[panzer1b]

Payload = missiles + bombs.

What else would you want to actually bring with you anyways, aside from the occasional tank or armored car.

[RocketBlam]

"Payload" by itself has actually little meaning. "Payload to low Kerbin orbit" may be more explicit.

This.

Think about the term itself. When Spacex puts something into orbit, they pay them to put a load into orbit.

The term itself is a bit meaningless in Kerbal though.

[Hasegawa]

Payload is the load that pays for the mission. Very simple, except for when it's complicated.

It's most clear in a commercial application. In an airline, for instance, payload is the passengers, their luggage, and any revenue cargo. The airplane, the flight crew, etc. are not payload.

But with something like Apollo 11 the whole purpose of the mission was to land some people on the moon. The astronauts were payload, really. (Well, maybe not Collins.)

And payload can depend on whether you are planning the whole mission or just working on the launch. If you are a launch engineer, the "payload" of a shuttle launch was the orbiter and everything in it. But if you were the mission planner, the "payload" was only whatever was in the cargo bay. And if you were a satcom company, the "payload" was just the part of the satellite that handled the communications. Everything else (the shuttle, the crew, the upper stage that boosted the satellite to its final orbit, and even the parts of the satellite intended for stationkeeping and the like) were not "payload".

In a way, the samples they picked up were/became part of the payload, especially on the later Apollo missions. Because that was part of the reason the missions were paid for and launched.

Fun thread. Payload is relative. My transfer stage + interplanetary probe are my launcher's payload, and the probe is the transfer stage's payload. Makes sense, no?

And that's why I'd go one further than this and list the scientific instruments (or relay antennas) as the payload of the probe.

[magnemoe]

Payload is the load that pays for the mission. Very simple, except for when it's complicated.

It's most clear in a commercial application. In an airline, for instance, payload is the passengers, their luggage, and any revenue cargo. The airplane, the flight crew, etc. are not payload.

But with something like Apollo 11 the whole purpose of the mission was to land some people on the moon. The astronauts were payload, really. (Well, maybe not Collins.)

And payload can depend on whether you are planning the whole mission or just working on the launch. If you are a launch engineer, the "payload" of a shuttle launch was the orbiter and everything in it. But if you were the mission planner, the "payload" was only whatever was in the cargo bay. And if you were a satcom company, the "payload" was just the part of the satellite that handled the communications. Everything else (the shuttle, the crew, the upper stage that boosted the satellite to its final orbit, and even the parts of the satellite intended for stationkeeping and the like) were not "payload".

This, payload is also dependent on target, an rocket like Falcon 9 has lower payload capacity to GTO than GEO, Payload to ISS is lower than GEO as it also need a spaceship who can intercept and dock with ISS.

Now the Moon landing did not have payload in the conversational sense. Same as your science missions in KSP.

It also show another issue, all the moon missions used the Saturn 5 3rd stage to both finish getting into orbit and for the moon intercept burn.

This is also common practice in KSP, using an disposable launcher its smart to do the last 3-500 m/s with with the deep space engine, guess its also common for other deep space missions who enter LEO before burning to target.

[percyPrune]

Now the Moon landing did not have payload

"Our mission... is to land a man on the moon and return him safely to Earth..." (JFK)

Sounds like a good payload definition. Mind you, If the moon landings were really about science, then the only worthwhile payload was Jack Schmitt

(Sorry. Just been reading "A Man on the Moon" by Andrew Chaikin)

Meanwhile, back OT... fascinating thread!