3.4.14 · D3Rocket Flight Mechanics

Worked examples — Pitch program — open-loop pitch-over

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This page is a case-by-case drill for the gravity-turn pitch program from the parent note. We take the one master law and push it into every corner: every angle regime, the two degenerate endpoints ( straight up, horizontal), the sign of the turn rate, a real launch word-problem, and an exam-style twist.

The single tool we lean on the whole way:


The scenario matrix

Every situation this topic can throw at you falls into one of these cells. The worked examples below are each tagged with the cell they cover.

Cell What makes it special Example
A. Near-vertical () , so — barely turns Ex 1
B. Mid-turn () large — fastest turning Ex 2
C. Near-horizontal () , but huge — turn slows again Ex 3
D. Speed dependence (fix , vary ) — the inverse law Ex 4
E. Degenerate: exactly vertical () — the "stuck" case, why a kick is needed Ex 5
F. Degenerate: exactly horizontal () maximum ; check burnout instant Ex 6
G. Real-world word problem convert units, find turn over a time window Ex 7
H. Exam twist: sign / integration eliminate time, , over-vs-under-kick Ex 8
Figure — Pitch program — open-loop pitch-over

The figure above plots across the whole turn. Notice the two ends (vertical and horizontal) are where the raw turning force is smallest and largest respectively — but the actual turn rate also divides by , which is why the real turning bunches up early (cell A→B) when is still small.


Worked examples

Ex 1 — Cell A: near-vertical, high speed

Ex 2 — Cell B: mid-turn, fastest bending

Ex 3 — Cell C: near-horizontal, very fast

Ex 4 — Cell D: the inverse-speed law

Ex 5 — Cell E: the degenerate vertical case

Ex 6 — Cell F: the degenerate horizontal case

Ex 7 — Cell G: real-world word problem

Ex 8 — Cell H: exam twist, eliminate time & judge the kick


Recall Which cell is the "stuck" one, and why?

Cell E, exactly ::: makes , so a perfectly vertical rocket never turns — the pitch kick must break this symmetry.

Recall Why does the fastest

turn rate NOT happen at horizontal (where is biggest)? Because ::: by the time is small, is huge, and the large speed in the denominator overwhelms the maximal .

See also: Gravity turn trajectory · Angle of attack and dynamic pressure (max-Q) · Thrust-to-weight ratio · Gravity loss and steering loss · Tsiolkovsky rocket equation · Closed-loop ascent guidance (PEG / IGM) · Attitude control and thrust vectoring (gimbal).