# ENAE 483/788D Principles of Space Systems Design Fall, 2002

## Question 4:

The Titan II launch vehicle was used to place the Gemini spacecraft into low earth orbit. The two stages of the Titan II had the following characteristics:

 Parameter Stage 1 Stage 2 Stage gross mass, kg 117,900 28,900 Stage propellant mass, kg 111,200 26,500 Specific impulse (sec) 296 316
The mass of the Gemini spacecraft was 3500 kg.

For both ENAE 483 and ENAE 788D:

a) Find the value of inert mass fraction (delta) for each stage.

b) Find the delta-V for each stage

c) I would like an extra 100 kg of payload. How much inert mass would you have to elimiate from the first stage to add this much payload?

d) How much extra propellant would you have to add to the second stage to gain an extra 100 kg of payload?

e) You would like to use the Titan II to inject a payload into a high elliptical earth orbit, such that the total launch delta-V is 10,500 m/sec. How much payload can the Titan II carry to this orbit?

For ENAE 788D only:

f) You would like to send a Gemini spacecraft on a circumlunar trip using Titan rocket technology. You need to reach a total delta-V of 12,500 m/sec for a successful translunar injection. Your idea is to duplicate the Titan first stage and use multiple copies as strap-on boosters. Assume the strap-on boosters are a "Stage 0" where all strap-ons fire in parallel at lift-off, and the previous first stage ignites when the boosters burn out. Further assume that the strap-on versions are identical to the first stage, except with an extra 500 kg of inert mass to account for an aerodynamic fairing. How many strap-on boosters will you need to ensure that the Gemini spacecraft is safely injected on an orbit to the moon?