Astro GR 3

Over expanded

Patm > Pexit

Under expanded

Patm < Pexit

Ideally epanded

Patm = Pexit

Liquid rocket advantage

can throttle, can stop/restart, high Isp

Liquid rocket disadvantage

complex propellant management (liquids are hard to manage in space)

Solid rocket advantage

simple, high thrust to weight ratio (F/W)

Solid rocket disadvantage

can’t restart/stop, can’t throttle

Hybrid rocket advantage

simpler than liquid, safer than solid, can throttle, can stop/restart

Hybrid rocket disadvantage

modest Isp

Isp (specific impulse)

measure of rocket’s efficiency in terms of propellant mass

chemical propulsion (required for launch)

F/W > 1 (150-455 Isp)

nuclear propulsion

political concerns limit use (800-1000 Isp)

electrical propulsion (used only in space)

very low thrust but very efficient (1000-10000 Isp)

2 Advantages of Staging

more total deltaV for same-sized launch vehicle, optimize nozzles for the area it operates in

2 Disadvantages of Staging

increased cost, increased complexity

2 attitude sensors

gyroscope, earth sensor

2 actuators

dampers, thrusters

Is smaller or greater D better for ADCS?

smaller D

Gain

ratio of energy it transmits in its primary direction to the energy that would be available from an omnidirectional source (gain for omnidirectional = 1, directional > 1)

Power

in Watts

Bandwidth

range of frequencies receiver is listening for

Range for worst case

Rmax

Range best case

R = h

three main sources of electrical power

solar, chemical, nuclear

solar (EPS)

only good up to Mars

chemical (EPS)

(ie: battery, fuel cell) primary batteries are only source of power

nuclear

must use past Mars

Depth of discharge (DoD)

% of total stored energy that is removed from battery during discharge period

Heat input in the sun

Solar Input, Albedo, Earth Shine

Heat Input in eclipse

Earth Shine

three methods of heat transfer

radiation, convection, conduction

what method of heat transfer do we use in space and why

radiation because the vacuum makes it the only option

what is fundamental frequency

lowest natural frequency where resonance can occur

resonance

vibrations that increase in amplitude

ideal relationship between f,fund and f,max

f,fund > f,max