test_vehicle_drag Namespace Reference

Functions
float	_built_length (cfg)
float	_smooth_friction_floor (cfg, float mach)
	shipped_flight ()
	test_drag_is_above_the_smooth_friction_floor (shipped_flight)
	test_thrusting_removes_the_nozzle_exit_from_the_base (shipped_flight)
	test_drag_grows_with_the_vehicle (shipped_flight)
	test_rougher_skin_more_drag (shipped_flight)
	test_flown_length_is_the_hand_stack (shipped_flight)
	test_full_burn_apogee_is_below_the_constant_cd_answer (shipped_flight)
	test_user_table_is_flown_as_given ()
	test_a_table_needs_its_pair_and_its_source ()
	test_turbulent_cf_against_prandtl_schlichting ()
	test_rough_cf_is_reynolds_independent ()
	test_isa_against_fluids ()
	test_nose_wave_drag_at_fineness_three_is_stoneys_table ()
	test_haack_wetted_area_against_a_hand_trapezoid ()

Variables
	rocketpy = pytest.importorskip("rocketpy")

Detailed Description

Drag of the flown vehicle (FLT-2).

The flight sim flew Cd 0.45 at every Mach, motor on and off, whatever the length, fins or finish.
The shipped vehicle is 7.76 m long on a 0.157 m body, 226 wetted areas per reference area: fully
turbulent skin friction alone exceeds 0.45. The build-up is Barrowman's as the OpenRocket technical
documentation (Niskanen 2013) gives it, on the geometry the sim assembles.

Independent sources here: Prandtl-Schlichting's smooth flat plate 0.455 / (log10 Re)^2.58, hand
geometry of the stack and the fins, the base-drag formula (Niskanen eq. 3.94 / sec. 3.4.5), the
1976 standard atmosphere from `fluids`, Stoney's fineness-3 table, and a hand trapezoid.

Function Documentation

_built_length()

float test_vehicle_drag._built_length ( cfg )

protected

Tail to nose tip as the sim stacks it, by hand: highest tank top + avionics length.

Definition at line 24 of file test_vehicle_drag.py.

References max.

Referenced by _smooth_friction_floor(), and test_flown_length_is_the_hand_stack().

_smooth_friction_floor()

float test_vehicle_drag._smooth_friction_floor ( cfg, float mach )

protected

0.12 base + smooth turbulent plate friction on the wetted area, Prandtl-Schlichting.

Definition at line 34 of file test_vehicle_drag.py.

References _built_length().

Referenced by test_drag_is_above_the_smooth_friction_floor().

shipped_flight()

test_vehicle_drag.shipped_flight

(

)

Definition at line 48 of file test_vehicle_drag.py.

References fly().

test_a_table_needs_its_pair_and_its_source()

test_vehicle_drag.test_a_table_needs_its_pair_and_its_source

(

)

Definition at line 114 of file test_vehicle_drag.py.

test_drag_grows_with_the_vehicle()

test_vehicle_drag.test_drag_grows_with_the_vehicle

(

shipped_flight

)

Definition at line 72 of file test_vehicle_drag.py.

References fly().

test_drag_is_above_the_smooth_friction_floor()

test_vehicle_drag.test_drag_is_above_the_smooth_friction_floor

(

shipped_flight

)

Definition at line 53 of file test_vehicle_drag.py.

References _smooth_friction_floor().

test_flown_length_is_the_hand_stack()

test_vehicle_drag.test_flown_length_is_the_hand_stack

(

shipped_flight

)

Definition at line 87 of file test_vehicle_drag.py.

References _built_length().

test_full_burn_apogee_is_below_the_constant_cd_answer()

test_vehicle_drag.test_full_burn_apogee_is_below_the_constant_cd_answer

(

shipped_flight

)

Most favourable plausible build-up (smooth, the 6.43 m length) gives 3803 m AGL by an
independent 1-DOF (audit); Cd 0.45 gave 4033 m.

Definition at line 96 of file test_vehicle_drag.py.

test_haack_wetted_area_against_a_hand_trapezoid()

test_vehicle_drag.test_haack_wetted_area_against_a_hand_trapezoid

(

)

Definition at line 166 of file test_vehicle_drag.py.

References max.

test_isa_against_fluids()

test_vehicle_drag.test_isa_against_fluids

(

)

Definition at line 146 of file test_vehicle_drag.py.

test_nose_wave_drag_at_fineness_three_is_stoneys_table()

test_vehicle_drag.test_nose_wave_drag_at_fineness_three_is_stoneys_table

(

)

(B.9) scales Stoney's fineness-3 curve by log4(fN + 1), which is 1 at fN = 3.

Definition at line 157 of file test_vehicle_drag.py.

test_rough_cf_is_reynolds_independent()

test_vehicle_drag.test_rough_cf_is_reynolds_independent

(

)

(3.80): 0.032 (Rs/L)^0.2 above the critical Re, whatever Re.

Definition at line 136 of file test_vehicle_drag.py.

test_rougher_skin_more_drag()

test_vehicle_drag.test_rougher_skin_more_drag

(

shipped_flight

)

Definition at line 79 of file test_vehicle_drag.py.

References fly().

test_thrusting_removes_the_nozzle_exit_from_the_base()

test_vehicle_drag.test_thrusting_removes_the_nozzle_exit_from_the_base

(

shipped_flight

)

Cd_off - Cd_on = (0.12 + 0.13 M^2) A_exit / A_ref, nothing else changes with the motor.

Definition at line 60 of file test_vehicle_drag.py.

test_turbulent_cf_against_prandtl_schlichting()

test_vehicle_drag.test_turbulent_cf_against_prandtl_schlichting

(

)

Definition at line 129 of file test_vehicle_drag.py.

test_user_table_is_flown_as_given()

test_vehicle_drag.test_user_table_is_flown_as_given

(

)

Definition at line 102 of file test_vehicle_drag.py.

References fly().

Variable Documentation

rocketpy

test_vehicle_drag.rocketpy = pytest.importorskip("rocketpy")

Definition at line 21 of file test_vehicle_drag.py.