What is Delta v: Definition and 15 Discussions

Delta-v (more known as "change in velocity"), symbolized as ∆v and pronounced delta-vee, as used in spacecraft flight dynamics, is a measure of the impulse per unit of spacecraft mass that is needed to perform a maneuver such as launching from or landing on a planet or moon, or an in-space orbital maneuver. It is a scalar that has the units of speed. As used in this context, it is not the same as the physical change in velocity of the vehicle.
As a simple example, take a conventional rocket-propelled spacecraft which achieves thrust by burning fuel. The spacecraft's delta-v is the change in velocity that spacecraft can achieve by burning its entire fuel load.
Delta-v is produced by reaction engines, such as rocket engines, and is proportional to the thrust per unit mass and the burn time. It is used to determine the mass of propellant required for the given maneuver through the Tsiolkovsky rocket equation.
For multiple maneuvers, delta-v sums linearly.
For interplanetary missions, delta-v is often plotted on a porkchop plot, which displays the required mission delta-v as a function of launch date.

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  1. R

    Delta V Calculator: Launch in an Atmosphere & Orbit Dimensions

    So I am making a Delta V calculator. Here it is: https://www.desmos.com/calculator/hib7psndtb Anyone know how to figure out a rocket's Delta V if it launches from in an atmosphere? Also, if I messed up on anything (in the Delta V calculator or isp calculator), please let me know so I could...
  2. T

    B Orbit circularisation/insertion spreadsheet

    I am trying to create a spreadsheet that will calculate: The minimum delta-v required to circularise the orbit of a projectile that has been fired horizontally from the Earths surface at a given velocity. Completely ignoring atmospheric drag. See the attached spreadsheet. The steps are...
  3. Oannes

    Finding Increse in Volume Given Temp, Vol Expansion....

    Homework Statement I am supposed to find the increase in volume, or more specifically how much mercury will rise inside of a thermometer, given the following values. The volume expansion is 1.8 * 10-4/C(degree Celcius). The temperature increase from 30 to 70 degrees F (already converted the...
  4. T

    How fast to shoot a bullet for it to hit the moon?

    Ignoring the fact that the atmospheric friction would probably disintegrate it. I know that to achieve LEO takes around 10km/s delta v. But only 2km/s of that is to overcome the drag and gravity. So you could shoot at 2km/s, get to LEO altitude then it falls back down because it is not at...
  5. G

    Relationship between characteristic energy and delta-v

    Firstly, apologies if this is in the wrong thread. I'm currently writing a presentation on the physics of getting a spacecraft from Earth to Mars in the near future. In my research I've come up against Porkchop plots which seem to plot contours of equal characteristic energy so you can find...
  6. starchaser2020

    Calculating Delta V for Orbit Change

    A satellite changes its orbit inclined 66° at 260.0 km altitude to a polar orbit at the same altitude. What Delta V was required? ... I am stuck. do I figure it out using: DeltaV1 = |V_transfer at orbit 1 - V_orbit 1| and DeltaV2 = |V_transfer at orbit 2 - V_orbit 2| or is there another...
  7. B

    How Is Delta V Loss Calculated for Spacecraft?

    How do you calculate how much delta v is lost from gravity and atmospheric drag? I've been looking for days but I can't find anything that actually tells me how it's calculated. For example it takes 1.5 km/s - 2 km/s extra delta v for a low Earth orbit because of drag loss, how was that number...
  8. M

    Delta v and change in velocity

    If the velocity of the object of 5 kg changed from 5 m/s to 4 m/s. Then is the change in kinetic energy -22.5 J or +22.5J. doesn't change mean final velocity minus initial velocity?
  9. A

    I want to calculate the delta V

    I want to calculate the delta V needed to move objects around in a 1-d gravitational field. The relevant equations as far as I can see are the Tsiolkovsky equation, \Delta V = v_{ex} \ln\left(\frac{m_0}{m_1}\right) and the equation for calculating escape velocity. v_e = \sqrt{\frac{2GM}{r}}...
  10. U

    What is the difference between Δv/Δt and dv/dt in calculus?

    I know delta means change , but I don't what the difference between Δv/Δt vs dv/dt is ? I am at the noob end of calculus so trying to grasp how to interpret things like dv/dt or what what dv would mean if it were standing alone. TIA
  11. A

    Delta V as a Function of Altitude

    Greetings everyone! I have a question on how the delta-V required to reach different orbits is determined. I refer to lift-off delta-V. I'm curious to find the relationship between altitude and delta V required to get to the height. From what I have found out, the lift-off delta v to a...
  12. T

    RC Circuit ; why RC=(VT/2 delta V)

    Homework Statement I need to prove that RC=(VT/2 delta V) Select the circle components of Charging and discharging of a capacitor Measure the resistance of resistor with a multimeter When you run a different frequency the cycle time change run different frequency that T<<tao, T=tao...
  13. M

    Finding Delta V of a Rocket: An Overview

    I am doing an assignment about launching a rocket and at the moment I am looking for the delta V of the rocket. I have done a few researches and i found a method of finding the energy of the rocket and find the delta vee of it , but then i found this article and I am not sure if it is delta vee...
  14. O

    Impulsive delta v hyperbolic and elliptical orbit

    Homework Statement On July 1, 2004, the Cassini spacecraft approached Saturn with hyperbolic excess velocity 5.5 km/s to swing by the planet at the closest approach distance rp = 80,680 km. Compute the impulsive ΔV required for a maneuver performed at the closest approach to Saturn to...
  15. D

    Help me im in WAS and i need to know Delta V. .

    help me please I am in WAS and i need to know Delta V. please please please. ok i am curently in WAS(wa arowspace scolars) I am a bad speller but i could care less also I am new hear. i know what the formula for delta v is but i do not understand it. i am interested in learning but please putin...