Self-Assessment Quiz: Launch Vehicles

Twenty questions to check your grasp of launch-vehicle families, performance, launch-site geometry, windows, the countdown, and vehicle selection. Answer each before opening the key. Aim for 16 or more. Use Earth's equatorial rotation speed $0.465\ \text{km/s}$ and $\cos i = \cos\phi\sin\beta$ where needed.

Question 1

A "launch vehicle" is best described as:

A) the satellite or probe that is the point of the mission B) the rocket that carries a payload from the ground to orbit or escape C) the upper stage only D) the ground-support equipment at the pad

Question 2

For most vehicles, payload to GTO compared with payload to LEO is:

A) about the same B) roughly 2–3 times smaller C) roughly 2–3 times larger D) exactly half

Question 3

The main reason GTO payload is smaller than LEO payload is that reaching GTO requires the vehicle to supply:

A) a larger fairing B) more delta-v, which the rocket equation pays for in payload C) a higher launch azimuth D) solid rocket boosters

Question 4

Which propellant combination is used by Starship, Vulcan's first stage, and New Glenn?

A) kerolox B) hydrolox C) methalox D) hypergolic

Question 5

The free eastward velocity a due-east launch gains from Earth's rotation at latitude $\phi$ is:

A) $0.465\ \text{km/s}$ at every latitude B) $0.465\sin\phi\ \text{km/s}$ C) $0.465\cos\phi\ \text{km/s}$ D) zero except at the poles

Question 6

The minimum orbital inclination reachable by a direct launch from a site at latitude $\phi$ is:

A) $0^\circ$ B) $90^\circ - \phi$ C) $\phi$ D) $2\phi$

Question 7

To launch from Cape Canaveral ($\phi = 28.5^\circ$) into a higher-inclination orbit such as the ISS's $51.6^\circ$, you launch:

A) due east B) due west C) on a more northerly (or southerly) azimuth than due east D) straight up

Question 8

Recovering a Falcon 9 first stage instead of expending it:

A) increases LEO payload B) leaves LEO payload unchanged C) decreases LEO payload (from ~22.8 t to ~17 t) D) is impossible

Question 9

Cost per kilogram to orbit is described in the chapter as:

A) a fixed, precise property of each rocket B) the softest and most abused number in rocketry C) identical for LEO and GTO D) always lower for expendable vehicles

Question 10

A launch that must rendezvous with the ISS has an instantaneous (or near-instantaneous) window because it must match the target's:

A) inclination only B) altitude only C) both orbital plane and phase along the orbit D) launch azimuth only

Question 11

Over the minutes of an ascent, a target orbital plane is approximately:

A) rotating with the Earth B) fixed in inertial space, with the launch site rotating under it C) changing inclination rapidly D) undefined

Question 12

A "built-in hold" in a countdown is:

A) an unplanned emergency stop (a scrub) B) a planned pause where the clock stops so teams can catch up or time the window C) the moment of engine ignition D) a weather violation

Question 13

In a GO/NO-GO poll, a single station calling "NO-GO":

A) is overruled by majority vote B) is ignored during terminal count C) stops the count D) only delays fueling

Question 14

Solid rocket boosters are ignited last (at T-0, after the liquid engines) because:

A) they are less powerful B) they cannot be shut down once lit, so everything else is confirmed first C) they need the liquid exhaust to ignite D) they are cheaper

Question 15

Which is a hard gate (pass/fail) in launch-vehicle selection, rather than a soft preference?

A) price B) schedule C) payload mass-to-orbit with margin D) operator reputation

Question 16 (True/False, justify)

"A vehicle that can lift ten of my satellites by mass can always launch all ten at once." True or false? Justify in one sentence.

Question 17 (True/False, justify)

"Because Kourou is near the equator, a satellite launched from there to GEO needs less of its own propellant than one launched from Cape Canaveral." True or false? Explain briefly.

Question 18 (Short answer)

In one or two sentences, explain why reusability shifts the weights in the vehicle-selection trade toward price and cadence and away from minimum-mass spacecraft design.

Question 19 (Short answer)

A site is at latitude $\phi = 34^\circ$. Give (a) the minimum inclination it can reach directly and (b) whether it can reach a $28^\circ$-inclined orbit without a plane change.

Question 20 (Short answer)

Compute the eastward rotation credit at Baikonur ($\phi = 45.9^\circ$), showing $0.465\cos\phi$, and say in one sentence why it is smaller than the credit at the Cape.

Answer Key

Q Ans Note
1 B The launch vehicle carries the payload; the payload is the spacecraft that is the mission's point.
2 B GTO capacity is ~2–3× smaller than LEO because the vehicle must supply ~2.4 km/s more delta-v.
3 B Extra delta-v converts would-be payload into propellant via $m_0/m_f = e^{\Delta v/v_e}$.
4 C Methalox (methane + LOX) — the reuse-friendly newcomer chosen by Starship, Vulcan, New Glenn.
5 C $v_{\text{rot}} = 0.465\cos\phi$; full credit at the equator, zero at the poles.
6 C Due east gives $\cos i = \cos\phi$, so $i = \phi$; you cannot go below your latitude directly.
7 C A more northerly/southerly azimuth raises inclination above the site's minimum $\phi$.
8 C Landing propellant is payload not lifted, so recovered payload drops (~22.8 t → ~17 t).
9 B It depends on orbit, fill fraction, and price-vs-cost — never a single clean number.
10 C Rendezvous requires matching plane and phase, collapsing the window to an instant.
11 B The plane is inertially fixed over the ascent; the rotating site swings into it ≤ twice/day.
12 B A planned pause (clock stopped) to synchronize the team and hit the window; a scrub is unplanned.
13 C Unanimity rule: any NO-GO halts the count. No one is overruled or pressured.
14 B Solids cannot be throttled or shut off, so they are the point of no return, lit last.
15 C Mass-to-orbit (with margin) is a pass/fail gate; price, schedule, and reputation are soft rankings.
16 False It may be volume-limited: the satellites must also fit in the fairing, which can bind before mass does.
17 True Kourou's low latitude means a smaller launch inclination, so a smaller (cheaper) plane change to reach equatorial GEO.
18 — Cheap, frequent launch makes launch mass affordable, so shaving grams matters less than lowering build cost and time; a heavier, simpler, mass-produced satellite can win.
19 — (a) $34^\circ$; (b) no — $28^\circ < 34^\circ$, so it needs a plane change.
20 — $0.465\cos 45.9^\circ = 0.465 \times 0.696 = 0.324\ \text{km/s}$; smaller because Baikonur is farther from the equator (larger $\phi$, smaller $\cos\phi$) than the Cape.

Topics to review by question

Questions Topic Section
1, 4 Launch-vehicle families & propellants §30.1
2, 3, 8, 9 Performance: payload, GTO vs LEO, reuse, cost §30.2
5, 6, 7, 17, 19, 20 Launch-site latitude & azimuth §30.3
10, 11 Launch windows §30.4
12, 13, 14 Countdown & GO/NO-GO §30.5
15, 16, 18 Choosing a launch vehicle §30.6

Target score: 16 / 20. If you missed several in §30.3, redo the worked example there by hand — the azimuth-inclination relation and the GEO plane-change penalty are the chapter's load-bearing calculations.