# How much rocket fuel is burned in the first mile/kilometer?

• vjk2
In summary, single-stage rockets that reach low Earth orbit require a large amount of fuel, with an estimated 88.4% of the initial total mass being propellant. The concept of single-stage-to-orbit launch vehicles has not yet been successfully achieved, and most satellites are delivered using multi-stage launch vehicles. Factors such as engine efficiency and acceleration play a significant role in the performance and efficiency of rocket launches.
vjk2
Take a typical single-stage rocket that reaches low Earth orbit (that's around 2000 km).

How much fuel is burnt just to get the thing a foot off the ground? Or a kilometer or a mile? 10%?

vjk2 said:
Take a typical single-stage rocket that reaches low Earth orbit (that's around 2000 km).

How much fuel is burnt just to get the thing a foot off the ground? Or a kilometer or a mile? 10%?
According to this site - http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Single-stage-to-orbit.html - "No Earth-launched SSTO launch vehicles have ever been constructed." Even the Space Shuttle uses booster rockets to lift the external tank with the shuttle. Most satellites are delivered with mutltistage launch vehicles.

To put things into perspective - http://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html

http://www.braeunig.us/space/propel.htm

Oops.

Okay, repurpose the question. For the space shuttle and Saturn rockets, how much fuel is needed to get off the ground? A km/mile?

HOw much is saved by ejecting spent stages?

You can calculate it yourself:
http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation
A hypothetical example from the wiki page:

Assume an exhaust velocity of 4.5 km/s and a \Delta v of 9.7 km/s (Earth to LEO).

Single stage to orbit rocket: 1-e^{-9.7/4.5} = 0.884, therefore 88.4% of the initial total mass has to be propellant. The remaining 11.6% is for the engines, the tank, and the payload. In the case of a space shuttle, it would also include the orbiter.

Single stage launchers to orbit have not been done. Performance would suffice easily since several decades ago, but an SSTO wouldn't be very efficient. Additionally, it would need an engine that throttles much stronger than they presently do, so the acceleration remains bearable at the end, adn preferably that is efficient in the atmosphere and in vacuum - but if using two engines with different thrust, why throw them away both at the end instead of successively?

So SSTO makes sense mainly if the launcher is reusable - and this can be done easily with two stages.

Also, most launchers want to go to GTO or GSO, not LEO, and then a single stage is much harder.

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Quite a bit performance is lost at the beginning. This would improve if accelerating stronger, BUT
- A stronger engine with the same nozzle diameter is less efficient
- An engine as strong that lifts more propellant delivers more payload for nearly the same cost.

As a result, launchers lift-off at 1+0.3G to sometimes 1+0.6G, though Saturn V had only 1+0.17G.

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If starting at 1+0.3G as is common, the first km is reached after 26s, it costs 336m/s performance while the launcher has only 77m/s there, so the weak acceleration wastes 259m/s performance in the first km - over some 9500m/s performance to reach low orbit.

Atmospheric drag is very small on medium or big launchers. This would enable a stronger acceleration as well, but faster through the air means a stronger stress on the launcher.

When evaluating the gravity losses on a launcher, one should not compare the performance with the orbital speed! The altitude needs some performance as well, with an ideal Hohmann transfer to circular 400km consuming about 1000m/s over the orbital speed.

Neither are the estimated 259m/s what launch from an aeroplane or mountain would bring.

Put together, an idealized launch scenario would save less than 1000m/s performance or just 1/3 of the start mass - which tells why most launchers are desperately classical. Earbreathing would bring more only if used at an important fraction of the 9500m/s, which is not even considered presently.

## 1. How is the amount of rocket fuel burned in the first mile/kilometer calculated?

The amount of rocket fuel burned in the first mile/kilometer is calculated by multiplying the specific impulse (a measure of rocket engine efficiency) by the rocket's total mass (including fuel) and dividing it by the acceleration of gravity.

## 2. What is the average amount of rocket fuel burned in the first mile/kilometer?

The average amount of rocket fuel burned in the first mile/kilometer varies depending on the type of rocket and its payload, but it typically ranges from 3,000 to 6,000 pounds of fuel per second.

## 3. How does the weight of the payload affect the amount of rocket fuel burned in the first mile/kilometer?

The weight of the payload does not directly affect the amount of rocket fuel burned in the first mile/kilometer, but it does impact the overall amount of fuel needed for the entire journey. A heavier payload requires more fuel to lift off the ground and reach the first mile/kilometer mark.

## 4. Is the amount of rocket fuel burned in the first mile/kilometer the same for all rockets?

No, the amount of rocket fuel burned in the first mile/kilometer can vary greatly depending on the type of rocket, its size, and the distance it needs to travel. Rockets designed for short distances will burn less fuel in the first mile/kilometer than those designed for longer distances.

## 5. How does the speed of the rocket affect the amount of fuel burned in the first mile/kilometer?

The speed of the rocket does not directly affect the amount of fuel burned in the first mile/kilometer. However, a faster rocket will generally reach the first mile/kilometer mark sooner and therefore burn the fuel more quickly than a slower rocket.

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