Difference between revisions of "Cheat sheet"

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Kerbal Space Program rocket scientist's '''cheat sheet''': Delta-v maps, equations and more for your reference so you can get from here to there and back again.
 
Kerbal Space Program rocket scientist's '''cheat sheet''': Delta-v maps, equations and more for your reference so you can get from here to there and back again.
  
== Mathematics ==
+
= Mathematics =
=== Delta-v (Δv) ===
+
== Thrust to weight ratio (TWR) ==
==== Basic calculation ====
+
{{See also|Terminology#TWR|Terminology}}
 +
This is Newton's Second Law. If the ratio is less than 1 the craft will not lift off the ground.
 +
 
 +
<math>\text{TWR} = \frac{F}{m \cdot g}</math>
 +
 
 +
== Combined specific impulse (I<sub>sp</sub>) ==
 +
If the I<sub>sp</sub> is the same for all engines in a stage, then the I<sub>sp</sub> is equal to a single engine. If the I<sub>sp</sub> is different for engines in a single stage, then use the following equation:
 +
 
 +
<math>I_{sp} = \frac{(F_1 + F_2 + \dots)}{\frac{F_1}{I_{sp1}} + \frac{F_2}{I_{sp2}} + \dots}</math>
 +
 
 +
== Delta-v (&Delta;v) ==
 +
===&Delta;v Basic calculation ===
 
{{See also|Tutorial:Advanced Rocket Design}}
 
{{See also|Tutorial:Advanced Rocket Design}}
 
Basic calculation of a rocket's &Delta;v. Use the atmospheric and vacuum thrust values for atmospheric and vacuum &Delta;v, respectively.
 
Basic calculation of a rocket's &Delta;v. Use the atmospheric and vacuum thrust values for atmospheric and vacuum &Delta;v, respectively.
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<math>\Delta{v} = ln\left(\frac{M_{start}}{M_{end}}\right) \cdot I_{sp} \cdot 9.81 \frac{m}{s^2}</math>
 
<math>\Delta{v} = ln\left(\frac{M_{start}}{M_{end}}\right) \cdot I_{sp} \cdot 9.81 \frac{m}{s^2}</math>
  
==== Transitional (true) &Delta;v ====
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=== Transitional (true) &Delta;v of a Stage that Crosses from Atmosphere to Vacuum ===
 
{| class="wikitable" style="float:left;margin:0.5em;"
 
{| class="wikitable" style="float:left;margin:0.5em;"
 
! Body !! &Delta;v<sub>out</sub>
 
! Body !! &Delta;v<sub>out</sub>
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| other bodies' || data missing
 
| other bodies' || data missing
 
|}
 
|}
Calculation of a rocket's &Delta;v, taking an atmosphere into account. &Delta;v<sub>out</sub> is the amount of &Delta;v required to leave a body's atmosphere, ''not'' reach orbit. This equation is useful to figure out the actual &Delta;v of a stage that ''transitions'' from atmosphere to vacuum.
+
Calculation of a rocket stage's &Delta;v, taking into account transitioning from atmosphere to vacuum. &Delta;v<sub>out</sub> is the amount of &Delta;v required to leave a body's atmosphere, ''not'' reach orbit. This equation is useful to figure out the actual &Delta;v of a stage that ''transitions'' from atmosphere to vacuum.
  
 
<math>\Delta{v}_T = \frac{\Delta{v}_{atm} - \Delta{v}_{out} \frac{m}{s^2}}{\Delta{v}_{atm}} \cdot \Delta{v}_{vac} + \Delta{v}_{out} \frac{m}{s^2}</math>
 
<math>\Delta{v}_T = \frac{\Delta{v}_{atm} - \Delta{v}_{out} \frac{m}{s^2}}{\Delta{v}_{atm}} \cdot \Delta{v}_{vac} + \Delta{v}_{out} \frac{m}{s^2}</math>
 
{{clear|left}}
 
{{clear|left}}
  
==== Maps ====
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=== Maps ===
[[File:KerbinDeltaVMap.png|thumb|&Delta;v to all bodies in the [[Kerbol System]]]]
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[[File:KerbinDeltaVMap.png|&Delta;v to all bodies in the [[Kerbol System]]]]
 
Various fan-made maps showing the &Delta;v required to travel to a certain body.
 
Various fan-made maps showing the &Delta;v required to travel to a certain body.
  
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* http://ubuntuone.com/1kD39BCoV38WP1QeG6MtO6
 
* http://ubuntuone.com/1kD39BCoV38WP1QeG6MtO6
  
=== Thrust to weight ratio (TWR) ===
+
= Math Examples =
{{See also|Terminology#TWR|Terminology}}
 
This is Newton's Second Law. If the ratio is less than 1 the craft will not lift off the ground.
 
 
 
<math>\text{TWR} = \frac{F}{m \cdot g}</math>
 
 
 
=== Combined specific impulse (I<sub>sp</sub>) ===
 
If the I<sub>sp</sub> is the same for all engines in a stage, then the I<sub>sp</sub> is equal to a single engine. If the I<sub>sp</sub> is different for engines in a single stage, then use the following equation:
 
  
<math>I_{sp} = \frac{(F_1 + F_2 + \dots)}{\frac{F_1}{I_{sp1}} + \frac{F_2}{I_{sp2}} + \dots}</math>
+
==TWR==
 +
draft
 +
==(I<sub>sp</sub>)==
 +
draft
 +
==(&Delta;v)==
 +
draft
  
== See also ==
+
= See also =
 
Links to collections of reference material.
 
Links to collections of reference material.
 
* [[Tutorials]]
 
* [[Tutorials]]
 
* [[Terminology]]
 
* [[Terminology]]
 
* [[thread:28352|The Drawing Board: A library of tutorials and other useful information]]
 
* [[thread:28352|The Drawing Board: A library of tutorials and other useful information]]

Revision as of 17:52, 3 July 2013

Kerbal Space Program rocket scientist's cheat sheet: Delta-v maps, equations and more for your reference so you can get from here to there and back again.

Mathematics

Thrust to weight ratio (TWR)

→ See also: Terminology

This is Newton's Second Law. If the ratio is less than 1 the craft will not lift off the ground.

Combined specific impulse (Isp)

If the Isp is the same for all engines in a stage, then the Isp is equal to a single engine. If the Isp is different for engines in a single stage, then use the following equation:

Delta-v (Δv)

Δv Basic calculation

→ See also: Tutorial:Advanced Rocket Design

Basic calculation of a rocket's Δv. Use the atmospheric and vacuum thrust values for atmospheric and vacuum Δv, respectively.

Transitional (true) Δv of a Stage that Crosses from Atmosphere to Vacuum

Body Δvout
Kerbin 1000 m/s2
other bodies' data missing

Calculation of a rocket stage's Δv, taking into account transitioning from atmosphere to vacuum. Δvout is the amount of Δv required to leave a body's atmosphere, not reach orbit. This equation is useful to figure out the actual Δv of a stage that transitions from atmosphere to vacuum.

Maps

Δv to all bodies in the Kerbol System Various fan-made maps showing the Δv required to travel to a certain body.

Total Δv values

Δv change values

Δv nomogram

Math Examples

TWR

draft

(Isp)

draft

(Δv)

draft

See also

Links to collections of reference material.