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

1. Jan 7, 2008

### davo

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

ok i am curently in WAS(wa arowspace scolars) im a bad speller but i could care less also im 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 into layman's terms. also hear is the Question. De-orbit maneuvers are usually done to lower the perigee of the orbit to 60 miles (or less). The Orbiter is captured and re-enters as it passes into the atmosphere at this altitude.

There is a change of 1 mile for every 2 feet per second (fps) change in velocity when you are below a 500-mile altitude above the Earth.

Determine the change in velocity (delta-V) that the Shuttle will need to make if it is at an altitude of 220 miles above the Earth at apogee and 210 miles above the Earth at perigee, and needs to drop the perigee to an altitude of 60 miles.

2. Jan 7, 2008

### Kurdt

Staff Emeritus
Delta v in this context is simply the change in the velocity of the shuttle. That is the original velocity minus the final velocity.

3. Jan 7, 2008

### davo

ok so then (if i understand u) from what the question stated (for its speed) every time its decreasing a mile its travaling 2fps below a 500 mile altitude above the Earth? So then really their asking me: when is the shuttle going to reach a perigee of 60 miles and how meny mile's/fps? I will try and wok it out and see what i get.

4. Jan 7, 2008

### Kurdt

Staff Emeritus
So for every mile in altitude lost the velocity changes by 2fps. So if the altitude decreases by x miles then the change in velocity is 2x fps.

5. Jan 7, 2008

### davo

thank u so much man i will try it out and if u could tell me if it is right i would apreciate it. i should have it done soon.

6. Jan 7, 2008

### davo

ok so i came up with:it needs to travel 792,000ft to reach the 60 mile marker, and decreases 150 miles. am i right? sorry it took 4 ever i seam to compliate things and think of them in a bigger perportion even though they really arnt.

7. Jan 8, 2008

### Kurdt

Staff Emeritus
If it decreases by 150 miles then the change in speed is going to be 300 fps. fps = feet per second.

8. Jan 8, 2008

### seycyrus

What are your future plans? Perhaps you need to reevaluate the importance you put on proper communication skills.

I for one had a hard time getting past the incorrect spelling and grammar in your question.

9. Jan 8, 2008

### davo

ok thank you. You made it seem a hell of a lot easyer then what it looked like.