To install click the Add extension button. That's it.

The source code for the WIKI 2 extension is being checked by specialists of the Mozilla Foundation, Google, and Apple. You could also do it yourself at any point in time.

4,5
Kelly Slayton
Congratulations on this excellent venture… what a great idea!
Alexander Grigorievskiy
I use WIKI 2 every day and almost forgot how the original Wikipedia looks like.
Live Statistics
English Articles
Improved in 24 Hours
Added in 24 Hours
Languages
Recent
Show all languages
What we do. Every page goes through several hundred of perfecting techniques; in live mode. Quite the same Wikipedia. Just better.
.
Leo
Newton
Brights
Milds

From Wikipedia, the free encyclopedia

In aerospace engineering, mass ratio is a measure of the efficiency of a rocket. It describes how much more massive the vehicle is with propellant than without; that is, the ratio of the rocket's wet mass (vehicle plus contents plus propellant) to its dry mass (vehicle plus contents). A more efficient rocket design requires less propellant to achieve a given goal, and would therefore have a lower mass ratio; however, for any given efficiency a higher mass ratio typically permits the vehicle to achieve higher delta-v.

The mass ratio is a useful quantity for back-of-the-envelope rocketry calculations: it is an easy number to derive from either or from rocket and propellant mass, and therefore serves as a handy bridge between the two. It is also a useful for getting an impression of the size of a rocket: while two rockets with mass fractions of, say, 92% and 95% may appear similar, the corresponding mass ratios of 12.5 and 20 clearly indicate that the latter system requires much more propellant.

Typical multistage rockets have mass ratios in the range from 8 to 20. The Space Shuttle, for example, has a mass ratio around 16.

YouTube Encyclopedic

  • 1/3
    Views:
    6 078
    5 201
    20 613
  • Chemistry Question: Calculating the mass ratio of a chemical compund
  • Mass Ratios
  • Formula From Atomic Masses & Mass Ratio

Transcription

Derivation

The definition arises naturally from Tsiolkovsky's rocket equation:

where

  • Δv is the desired change in the rocket's velocity
  • ve is the effective exhaust velocity (see specific impulse)
  • m0 is the initial mass (rocket plus contents plus propellant)
  • m1 is the final mass (rocket plus contents)

This equation can be rewritten in the following equivalent form:

The fraction on the left-hand side of this equation is the rocket's mass ratio by definition.

This equation indicates that a Δv of times the exhaust velocity requires a mass ratio of . For instance, for a vehicle to achieve a of 2.5 times its exhaust velocity would require a mass ratio of (approximately 12.2). One could say that a "velocity ratio" of requires a mass ratio of .

Sutton defines the mass ratio inversely as:[1]

In this case, the values for mass fraction are always less than 1.

See also

References

Zubrin, Robert (1999). Entering Space: Creating a Spacefaring Civilization. Tarcher/Putnam. ISBN 0-87477-975-8.

  1. ^ Rocket Propulsion Elements, 7th Edition by George P. Sutton, Oscar Biblarz
This page was last edited on 10 June 2020, at 22:28
Basis of this page is in Wikipedia. Text is available under the CC BY-SA 3.0 Unported License. Non-text media are available under their specified licenses. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc. WIKI 2 is an independent company and has no affiliation with Wikimedia Foundation.