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

## Question 5:

The two-stage version of the Saturn V was used for placing heavy payloads into low earth orbit. It had the following characteristics:

 Parameter Stage 1 Stage 2 Stage gross mass, kg 2,286,000 542,000 Stage propellant mass, kg 2,151,000 487,700 Specific impulse (sec) 285 421
The payload to low earth orbit was 118,000 kg.

Feeling cheated that no one ever built a Nova launch vehicle, you decide to resurrect the Saturn V and add four space shuttle solid rocket boosters to the first stage as strap-ons. A single SRB has a gross mass of 589,700 kg, an empty mass of 86,180 kg, and an Isp of 269 sec.

For both ENAE 483 and ENAE 788D:

a) Find the delta-V achieved with the nominal 118,000 kg payload assuming the four SRBs are Stage 0, and the Saturn V first stage ignites at SRB burnout.

b) With the same assumption as (a), find the payload deliverable to low earth orbit (delta-V=9200 m/sec)

c) You notice that the thrust of four SRBs is not as large as the mass of the complete launch vehicle, so (a) is not an overly effective approach. Repeat (a) assuming the four SRBs burn in parallel with the Saturn stage 1. Assume both SRB and Stage 1 have constant propellant flow rates. The SRBs burn for 124 seconds; stage 1 burns for 161 seconds.

d) You wake up one morning, slap yourself on the forehead and say "Dohhh!!!" because you suddenly realize that it will take a bajillion dollars to restart the Saturn V production line. The key question now is, what are you going to do with all those SRBs you've already paid for? While taking a shower, the answer comes to you: modular launch vehicles! You decide to arrange 8 SRBs as a four-stage modular vehicle: 4 SRBs in the first stage, 2 in the second, and 1 each in the third and fourth stages. What delta-V can you achieve with a 10,000 kg payload?

For ENAE 788D only:

e) How much payload can (c) carry to low earth orbit?