Chapter 6 : Maneuvering in Space

Question 1

What is a Hohmann transfer?

Answer 1

The most efficient way to transfer from one orbit to another. It uses an elliptical transfer orbit tangent to the initial and final orbits

Question 2

What are the three limitations to the Hohmann transfer?

Answer 2

1. orbits are in the same plane (co-planar)
2. major axis (line of appsides) are aligned (coapsidal)
3. the change in velocities are tangent and instantaneous to the initial and final orbits

Question 3

How do you calculate a Hohmann transfer?

Answer 3

1. find semi major axis or transfer orbit
2. calculate the energies for each orbit (3 energies)
3. calculate the velocities for each orbit (4 velocities)
4. calculate the delta velocities (3 velocities)
5. calculate the period and or TOF

Question 4

What is a simple plane change?

Answer 4

change in plane that is the same size, but different inclination

Question 5

How to you calculate the velocity for a simple plane change?

Answer 5

set up a triangle, ∆V=2Vosin(θ/2)

Question 6

In a simple plane transfer, what is velocity dependent on?

Answer 6

Initial velocity and

angle its turning to

Question 7

How do you change only the inclination of a plane?

Answer 7

change the velocity at the ascending and descending nodes

Question 8

What is a combined plane transfer?

Answer 8

change to a different size and inclination

Question 9

How do you calculate a combined plane transfer?

Answer 9

set up an initial triangle like a simple plane transfer, and create a second, adjacent triangle with same height, hypotenuse ∆Vcombo, and leg ∆Vincrease.
there is a specific equation for the ∆Vcombo (that is what you are solving for)

Question 10

What does rendezvous mean?

Answer 10

meeting at the same place at the same time.

Question 11

What are the two types of rendezvous?

Answer 11

co planer and

co-orbital

Question 12

What are the steps to determining a co-planer rendezvous?

Answer 12

1. calculate the lead angle, alpha α
2. calculate the final phase angle, φ
3. determine the wait time

Question 13

What is a co-orbital rendezvous?

Answer 13

the target and the interceptor are on the same orbit

Question 14

What is a phasing orbit?

Answer 14

an orbit that the interceptor waits in until the target is in a certain spot

Question 15

How does the interceptor catch up to the target?

Answer 15

Slows down! Slower velocity will put the interceptor into a smaller orbit, smaller orbit means smaller period so the interceptor will catch up to the target

Question 16

How do you calculate a co-orbit rendezvous?

Answer 16

1. calculate the φ travel (angle target needs to travel)
2. calculate the TOF
3. calculate the semi-major axis of the phase orbit
4. calculate the velocities (like a transfer orbit) where the first ∆v puts the interceptor into the phasing orbit and the second ∆v returns the the interceptor to the original orbit.