Can someone explain to me the concept of DeltaV?

[Bearsh]

Title asks it all, I never knew much about dV Only that it is the amount of needed effort.

I've tried to understand it, But I'm not good at math AT ALL. So can someone try to explain it basically a newbs or dummy's way lol...

Because I've tried to calculate it and understand it and... It's just No and Void.

Edited April 26, 2014 by Bearsh

[Taki117]

so dV is the ammount of change in velocity your rocket has. if you want to perform a maneuver (such as moving to a higher orbit) you need to change your velocity by a certain ammount (the dV needed to perform the maneuver) how you do this is by expending fuel and using the stored energy to give your ship a push in the appropriate direction.

to figure out how much dV your ship has you use the rocket equation, (link not handy on phone) to calculate how much you can change your velocity by expending a certain percentage of your ships mass as fuel. (mass and weight are NOT the same thing)

[Claw]

Oh boy. This is a favorite topic on the forums.

It's basically a measure of how much you can do with your craft. Orbital mechanics is a lot of vector math, and delta V is a way to measure your ability to move the vector around.

The amount of dV a craft has basically depends on it's mass, the engine's fuel mileage (ISP), and how much fuel you have. A heavier ship, poor ISP, or less fuel, you will have less dV.

It is sort of like comparing a truck. If you have more gas in the tank, or a more efficient motor, you can go further. If you a hauling a boat behind the truck, you can't go quite as far.

Edited April 26, 2014 by Claw

[Bearsh]

so dV is the ammount of change in velocity your rocket has. if you want to perform a maneuver (such as moving to a higher orbit) you need to change your velocity by a certain ammount (the dV needed to perform the maneuver) how you do this is by expending fuel and using the stored energy to give your ship a push in the appropriate direction.

to figure out how much dV your ship has you use the rocket equation, (link not handy on phone) to calculate how much you can change your velocity by expending a certain percentage of your ships mass as fuel. (mass and weight are NOT the same thing)

Alright, So now I know why everytime I was finding my node to circularize an orbit I was always falling back down while turning my rocket.........................

So I need a longer orbit so I have enough time to setup a node so I can setup and find it and not worry about falling back down.

Yay my munar rocket isn't a failure!

(I always needed help with mechjeb) So thanks that helped me understand one of the problems and a lot about dV.

[Redshift OTF]

DeltaV is acceleration or change of speed. In space you are usually in some kind of orbit going at speed. To change you orbit you need to change your speed, either accelerate or de-accelerate and the amount and number of times you can do this is your total DeltaV. To change your speed you need thrust and fuel so these are what give you your total DeltaV.

[Taki117]

Alright, So now I know why everytime I was finding my node to circularize an orbit I was always falling back down while turning my rocket.........................

So I need a longer orbit so I have enough time to setup a node so I can setup and find it and not worry about falling back down.

Yay my munar rocket isn't a failure!

(I always needed help with mechjeb) So thanks that helped me understand one of the problems and a lot about dV.

Generally speaking if you are circularizing your orbit then your node is going to be slightly lower than your prograde marker (Assuming your navball is in orbit mode) meaning that you should always pitch towards the brown part of your navball once you get out of the atmosphere. if you are using MechJeb open up the maneuver planner, and have it create a node and then execute that node. You want to pay attention to which way Mechjeb Pitches your craft.

[GoatRider]

Disregarding friction and gravity, if you start out at 0 m/s, and you apply 1000 m/s delta-V in a straight line, you'll be going 1000 m/s. That's what it IS. The above comments tell you how to calculate it, and how to use it. Personally, I just use MechJeb.

[CaptainKipard]

DeltaV is acceleration...

No. Acceleration and Delta-V have different units of measurement.

[xcorps]

No. Acceleration and Delta-V have different units of measurement.

It took me a while to wrap my head around that concept.

[Redshift OTF]

No. Acceleration and Delta-V have different units of measurement.

Yes, you are correct, but it made my example easier to understand. Acceleration is m/s^2 right?

[Nedal]

yea, meters per second per second

or how many m/s you accelterate persecond.. Or you can use units of G

on earth/kerbin 1g =9.8m/s/s if you are in space and you accelerate at 1g or 9.8m/s/s for one minute or 60 seconds then 60x9.8 your deltaV would have been 588m/s

to find what G you can accerlate at you need to know your thrust to weight ratio TWR, a TWR of 1 means you can accerlate at 1g if you're on earth/kerbin surface that exactly counters gravity (but you'll burn some fuel and so your twr will increase). and so on and so forth.

Edited April 27, 2014 by Nedal

[CaptainKipard]

DV is total change in velocity, m/s

Acceleration is change in velocity per unit of time, m/s^2

g

G

Don't confuse those two.

G is the gravitational constant.

g is the acceleration due to gravity.

[Osprey]

Yes, you are correct, but it made my example easier to understand. Acceleration is m/s^2 right?

Yes.

Delta-V = Change in velocity in meters/seconds (v/t)

Acceleration = Rate of change of velocity in meters/seconds/seconds (v/t/t)

[Rickenbacker]

And just to make it very, very simple: If your rocket can increase its velocity by 100m/s before running out of fuel, it has 100m/s DeltaV. And so on. This measurement is not in the stock game, you'll need Kerbal Engineer or MechJeb to see it when building, and you'll need around 4500m/s DeltaV to get into orbit around Kerbin.

[dandrestor]

Yes.

Delta-V = Change in velocity in meters/seconds (v/t)

Acceleration = Rate of change of velocity in meters/seconds/seconds (v/t/t)

Or, considering the orbital energy, acceleration is somehow equivalent to the concept of orbital power, if there is such a thing. Does this make any sense to somebody more physics-savvy?

Dan

[LethalDose]

Or, considering the orbital energy, acceleration is somehow equivalent to the concept of orbital power, if there is such a thing. Does this make any sense to somebody more physics-savvy?

Dan

Specific orbital energy is a substantially more abstract concept than dV, and we really don't need it here. I'm not familiar with anyone that uses or discusses "orbital power".

Acceleration in terms of orbital maneuvers is associated with TWR. It's basically how quickly the vessel can spend it's dV. Higher TWR/Acceleration means shorter burns to achieve the same dV, but it has little to no directimpact on the vessels dV.