Launchers Flashcards
1
Q
Important points to choosing a launcher: (8)
A
- Cost
- Reliability
- Max. Acceleration
- Max. Payload capability
- Orbit Parameters
- Politics
- Availability
- Vibration - Shock levels
2
Q
Comparison between liquid, solid and hybrid propellants:
A
3
Q
Why is it important to choose launchers in the very early stage of mission design?
A
It has a great impact on the mission, as it determines:
- Orbit we can launch
- Max Payload capability & Payload Volume
- Relevant orbital parameters such as:
- Altitude
- RAAN
- Inclination
4
Q
What are the losses in terms of dV that a launcher has and how to deal with them?
A
-
GRAVITATIONAL LOSSES:
1. Gravity retards the vehicle experienced by launchers as long as it is in the gravitational field of the earth. -
To reduce them:
- Increase Thrust (↑ accel)
- Fast pitching maneuvers (decrease pitch angle)
- DRAG LOSSES:
-
Aerodynamic drag forces acting on the vehicle depending on:
- Angle of Attack (α)
- Density (ρ)
- Shape & size of the vehicle
-
To reduce them:
- ↓ Accel
- Gravity Turn
5
Q
How do we benefit the most out of a launch?
A
By using the earth rotation on our side and launching eastwards
6
Q
What’s the difference between serial & parallel staging?
A
7
Q
What is the pork chop graph and why is it useful?
A
- A provide info on the conditions of the capture orbit when the S/C arrives including the ToD.
- Shows the solution of orbital mechanics by Lambert Theorem.
- Shows contour of equal characteristic energy C3.
- Determines when launch opportunities exist in function of the capabilities S/C
8
Q
Why do launcher pitch shortly after launch?
A
- Due to the orbit we need to achieve is parallel to earth surface and thus, reducing the dV of the maneuver. Vertical S/C to horizontal S/C position.
- Also reduces gravity losses
9
Q
What is the Dog Leg maneuver?
A
Converts potential to kinetic energy and it is used for orbit inclination changes.
