SixDOF Thrust Producer Types¶
Definitions of thrust producer types (including turbine-driven jet engines like turbojets and turbofans, ramjets/scramjets, liquid-propellant rocket engines, and solid-propellant rocket motors) are performed outside within a six_dof_object_types block. These define ‘types’ of engines which can then be referenced from within a propulsion_data block within a rigid_body_vehicle_type or point_mass_vehicle_type block.
Because of differences in how flight controls are managed by RB6 and PM6, thrust producers also have slightly different inputs depending on whether their intended use is for RB6 or PM6 vehicles. A RB6 thrust producer must be defined within a rigid_body_engine_type block, and a PM6 thrust producer must be defined within a point_mass_engine_type block.
- rigid_body_engine_type <derived_type_name> <base_engine_name> … end_rigid_body_engine_type¶
Definitions for each type of engine are performed within the rigid_body_engine_type block. Since the definition is for a ‘type’ of engine and not an ‘instance’ of an engine, no installation position/attitude data is included. Typically, the fuel_feed is specified at the instance-level rather than at the type-level.
rigid_body_engine_type J79-GE-7 BASE_TYPE ... Jet- or rocket-specific commands ... // Thrust Offset Location thrust_offset ... // Reference Area When Inoperative inop_ref_area ... // Fuel Source for Engine fuel_feed ... // Thrust producer control handles throttle_setting_mil THROTTLE_MIL throttle_setting_ab THROTTLE_AB throttle_setting_reverser THRUST_REVERSER throttle_setting_yaw THRUST_VECTORING_YAW throttle_setting_pitch THRUST_VECTORING_PITCH end_rigid_body_engine_type- thrust_offset <length-value>¶
This is the location of the thrust relative to the engine’s reference point along the x-axis. A positive value is forward of the engine, negative is aft. This can have significant kinematic effects for rigid-body vehicles, but only affects visuals for point-mass systems.
- inop_ref_area <area-value>¶
This specifies aerodynamic CD-area product for the engine when it is inoperative. It is the drag coefficient multiplied by the reference area.
- fuel_feed <string>¶
This specifies the name of the fuel_tank from which the engine will draw fuel. This is typically specified for an engine instance rather than in the type definition.
- throttle_setting_mil <string>¶
This specifies the control_value defined in flight_controls that will be used to control the MIL (military) power throttle setting. This can be done in this block or in the propulsion_data of the rigid_body_vehicle_type.
- throttle_setting_ab <string>¶
This specifies the control_value defined in flight_controls that will be used to control the AB (afterburner) power throttle setting. This can be done in this block or in the propulsion_data of the rigid_body_vehicle_type.
- throttle_setting_reverser <string>¶
This specifies the control_value defined in flight_controls that will be used to control the thrust-reverser control setting. This can be done in this block or in the propulsion_data of the rigid_body_vehicle_type.
- throttle_setting_yaw <string>¶
This specifies the control_value defined in flight_controls that will be used to control the yaw thrust vectoring control setting. This can be done in this block or in the propulsion_data of the rigid_body_vehicle_type.
- throttle_setting_pitch <string>¶
This specifies the control_value defined in flight_controls that will be used to control the pitch thrust vectoring control setting. This can be done in this block or in the propulsion_data of the rigid_body_vehicle_type.
- point_mass_engine_type <derived_type_name> <base_engine_name> … end_point_mass_engine_type¶
Definitions for each type of engine are performed within the point_mass_engine_type block. Since the definition is for a ‘type’ of engine and not an ‘instance’ of an engine, no installation position/attitude data is included. Typically, the fuel_feed is specified at the instance-level rather than at the type-level.
point_mass_engine_type J79-GE-7 BASE_TYPE ... Jet- or rocket-specific commands ... // Thrust Offset Location thrust_offset ... // Reference Area When Inoperative inop_ref_area ... // Fuel Source for Engine fuel_feed ... end_point_mass_engine_type
Note the absence of throttle control handle information.
Engine types include:
Ramjet/Scramjet Engines (ramjet)
Liquid-Propellant Rocket Engines (liquid_propellant_rocket)
Solid-Propellant Rocket Motors (solid_propellant_rocket)
Each is detailed below.
Jet Engines (Turbojets and Turbofans)¶
- jet … end_jet¶
A jet block is intended to approximate engines incorporating a gas turbine, including turbojets and turbofans. The jet model leans heavily on input data, and so may also be suitable for aproximating propeller engines.
Since the definition is for a ‘type’ of engine and not an ‘instance’ of an engine, no installation position/attitude data is included. Typically, the fuel_feed is specified at the instance-level rather than at the type-level.
jet // Thrust Specific Fuel Consumption (TSFC) tsfc_idle_pph ... tsfc_mil_pph ... tsfc_ab_pph ... // Rated Thrust rated_thrust_idle ... rated_thrust_mil ... rated_thrust_ab ... // Idle Thrust Tables thrust_table_idle ... end_thrust_table_idle thrust_idle_mach_alt_table ... end_thrust_idle_mach_alt_table thrust_idle_alt_mach_table ... end_thrust_idle_alt_mach_table // Military (MIL) Thrust Tables thrust_table_mil ... end_thrust_table_mil thrust_mil_mach_alt_table ... end_thrust_mil_mach_alt_table thrust_mil_alt_mach_table ... end_thrust_mil_alt_mach_table // Afterburner (AB) Thrust Tables thrust_table_ab ... end_thrust_table_ab thrust_ab_mach_alt_table ... end_thrust_ab_mach_alt_table thrust_ab_alt_mach_table ... end_thrust_ab_alt_mach_table // Spin-Up Data spin_up_mil_per_sec ... spin_up_table_mil_per_sec ... end_spin_up_table_mil_per_sec spin_up_ab_per_sec ... spin_up_table_ab_per_sec ... end_spin_up_table_ab_per_sec // Spin-Down Data spin_down_mil_per_sec ... spin_down_table_mil_per_sec ... end_spin_down_table_mil_per_sec spin_down_ab_per_sec ... spin_down_table_ab_per_sec ... end_spin_down_table_ab_per_sec // Flag for smoking engines engine_smokes_above_power_setting ... end_jet- tsfc_idle_pph <real-value>¶
This specifies the thrust specific fuel consumption at idle in lbs-thrust/lbs-fuel/hr.
- tsfc_mil_pph <real-value>¶
This specifies the thrust specific fuel consumption at military power (full power without afterburner) in lbs-thrust/lbs-fuel/hr.
- tsfc_ab_pph <real-value>¶
This specifies the thrust specific fuel consumption using full afterburner in lbs-thrust/lbs-fuel/hr.
- rated_thrust_idle <force-value>¶
This specifies the thrust at idle. Since thrust varies with various conditions, this is a reference value.
- rated_thrust_mil <force-value>¶
This specifies the thrust at military power (full power without afterburner). Since thrust varies with various conditions, this is a reference value.
- rated_thrust_ab <force-value>¶
This specifies the thrust using full afterburner. Since thrust varies with various conditions, this is a reference value.
- thrust_table_idle¶
This is a simple table of idle thrust versus altitude. Note that is does not consider Mach-effects. The thrust_idle_mach_alt_table or thrust_idle_alt_mach_table are preferable, but if no Mach data is available, this table can be used.
thrust_table_idle # alt_ft thrust_lbs 0.0 10000.0 50000.0 2000.0 59000.0 100.0 60000.0 0.0 end_thrust_table_idle
- thrust_idle_mach_alt_table¶
This is an improved table over thrust_table_idle, since it includes Mach-effects. However, most users will prefer the format of the thrust_idle_alt_mach_table instead.
thrust_idle_mach_alt_table irregular_table independent_variable mach precision float independent_variable alt units ft dependent_variable precision float mach 0.0 alt 0.00 10000.0 30000.0 59000.0 60000.0 values 10000.0 8000.0 4000.0 100.0 0.0 ... mach 2.0 alt 0.00 10000.0 30000.0 59000.0 60000.0 values 10000.0 8000.0 4000.0 100.0 0.0 mach 3.0 alt 0.00 10000.0 30000.0 59000.0 60000.0 values 0.0 0.0 0.0 0.0 0.0 end_irregular_table end_thrust_idle_mach_alt_table
- thrust_idle_alt_mach_table¶
This is typically the best thrust table format – it includes Mach-effects and organizes its data in a preferred manner. The thrust_idle_mach_alt_table is an alternative format.
thrust_idle_alt_mach_table irregular_table independent_variable alt units ft independent_variable mach precision float dependent_variable precision float alt 0.0 mach 0.00 0.60 1.00 2.00 3.00 values 10000.0 10000.0 10000.0 10000.0 10000.0 ... alt 59000.0 mach 0.00 0.60 1.00 2.00 3.00 values 10000.0 10000.0 10000.0 10000.0 10000.0 alt 60000.0 mach 0.00 0.60 1.00 2.00 3.00 values 10000.0 10000.0 10000.0 10000.0 10000.0 end_irregular_table end_thrust_idle_alt_mach_table
- thrust_table_mil¶
This is a simple table of military (MIL) thrust versus altitude. Note that is does not consider Mach-effects. The thrust_mil_mach_alt_table or thrust_mil_alt_mach_table are preferable, but if no Mach data is available, this table can be used.
thrust_table_mil # alt_ft thrust_lbs 0.0 10000.0 50000.0 2000.0 59000.0 100.0 60000.0 0.0 end_thrust_table_mil
- thrust_mil_mach_alt_table¶
This is an improved table over thrust_table_mil, since it includes Mach-effects. However, most users will prefer the format of the thrust_mil_alt_mach_table instead.
thrust_mil_mach_alt_table irregular_table independent_variable mach precision float independent_variable alt units ft dependent_variable precision float mach 0.0 alt 0.00 10000.0 30000.0 59000.0 60000.0 values 10000.0 8000.0 4000.0 100.0 0.0 ... mach 2.0 alt 0.00 10000.0 30000.0 59000.0 60000.0 values 10000.0 8000.0 4000.0 100.0 0.0 mach 3.0 alt 0.00 10000.0 30000.0 59000.0 60000.0 values 0.0 0.0 0.0 0.0 0.0 end_irregular_table end_thrust_mil_mach_alt_table
- thrust_mil_alt_mach_table¶
This is typically the best thrust table format – it includes Mach-effects and organizes its data in a preferred manner. The thrust_mil_mach_alt_table is an alternative format.
thrust_mil_alt_mach_table irregular_table independent_variable alt units ft independent_variable mach precision float dependent_variable precision float alt 0.0 mach 0.00 0.60 1.00 2.00 3.00 values 10000.0 10000.0 10000.0 10000.0 10000.0 ... alt 59000.0 mach 0.00 0.60 1.00 2.00 3.00 values 10000.0 10000.0 10000.0 10000.0 10000.0 alt 60000.0 mach 0.00 0.60 1.00 2.00 3.00 values 10000.0 10000.0 10000.0 10000.0 10000.0 end_irregular_table end_thrust_mil_alt_mach_table
- thrust_table_ab¶
This is a simple table of afterburner (AB) thrust versus altitude. Note that is does not consider Mach-effects. The thrust_ab_mach_alt_table or thrust_ab_alt_mach_table are preferable, but if no Mach data is available, this table can be used.
thrust_table_ab # alt_ft thrust_lbs 0.0 10000.0 50000.0 2000.0 59000.0 100.0 60000.0 0.0 end_thrust_table_ab
- thrust_ab_mach_alt_table¶
This is an improved table over thrust_table_ab, since it includes Mach-effects. However, most users will prefer the format of the thrust_ab_alt_mach_table instead.
thrust_ab_mach_alt_table irregular_table independent_variable mach precision float independent_variable alt units ft dependent_variable precision float mach 0.0 alt 0.00 10000.0 30000.0 59000.0 60000.0 values 10000.0 8000.0 4000.0 100.0 0.0 ... mach 2.0 alt 0.00 10000.0 30000.0 59000.0 60000.0 values 10000.0 8000.0 4000.0 100.0 0.0 mach 3.0 alt 0.00 10000.0 30000.0 59000.0 60000.0 values 0.0 0.0 0.0 0.0 0.0 end_irregular_table end_thrust_ab_mach_alt_table
- thrust_ab_alt_mach_table¶
This is typically the best thrust table format – it includes Mach-effects and organizes its data in a preferred manner. The thrust_ab_mach_alt_table is an alternative format.
thrust_ab_alt_mach_table irregular_table independent_variable alt units ft independent_variable mach precision float dependent_variable precision float alt 0.0 mach 0.00 0.60 1.00 2.00 3.00 values 10000.0 10000.0 10000.0 10000.0 10000.0 ... alt 59000.0 mach 0.00 0.60 1.00 2.00 3.00 values 10000.0 10000.0 10000.0 10000.0 10000.0 alt 60000.0 mach 0.00 0.60 1.00 2.00 3.00 values 10000.0 10000.0 10000.0 10000.0 10000.0 end_irregular_table end_thrust_ab_alt_mach_table
- spin_up_mil_per_sec <real-value>¶
This defines how quickly the engine will “spool-up” as the power level is advanced. A value of 1.0 implies that the engine will spin-up from idle to MIL power in 1 second, while a value of 0.1 implies that it will take 10 seconds to spin-up from idle to MIL power.
- spin_up_table_mil_per_sec¶
This defines how quickly the engine will “spool-up” as the power level is advanced. Rather than a single value, this command uses a table that is a function of the throttle level (normalized), allowing a more realistic spin-up as a function of current power condition. A value of 1.0 implies that the engine will spin-up from idle to MIL power in 1 second, while a value of 0.1 implies that it will take 10 seconds to spin-up from idle to MIL power.
spin_up_table_mil_per_sec # throttle_level spin_up_per_sec 0.0 0.05 0.2 0.10 0.4 0.20 0.6 0.30 0.8 0.40 1.0 0.50 end_spin_up_table_mil_per_sec
- spin_up_ab_per_sec <real-value>¶
This defines how quickly the engine will “spool-up” as the power level is advanced. A value of 1.0 implies that the engine will spin-up from MIL to Full AB power in 1 second, while a value of 0.1 implies that it will take 10 seconds to spin-up from MIL to Full AB power.
- spin_up_table_ab_per_sec¶
This defines how quickly the engine will “spool-up” as the power level is advanced. Rather than a single value, this command uses a table that is a function of the throttle level (normalized), allowing a more realistic spin-up as a function of current power condition. A value of 1.0 implies that the engine will spin-up from MIL to Full AB power in 1 second, while a value of 0.1 implies that it will take 10 seconds to spin-up from MIL to Full AB power.
spin_up_table_ab_per_sec # throttle_level spin_up_per_sec 0.0 0.05 0.2 0.10 0.4 0.20 0.6 0.30 0.8 0.40 1.0 0.50 end_spin_up_table_ab_per_sec
- spin_down_mil_per_sec <real-value>¶
This defines how quickly the engine will “spool-down” as the power level is reduced. A value of 1.0 implies that the engine will spin-down from MIL power to idle in 1 second, while a value of 0.1 implies that it will take 10 seconds to spin-down from MIL power to idle.
- spin_down_table_mil_per_sec¶
This defines how quickly the engine will “spool-down” as the power level is reduced. Rather than a single value, this command uses a table that is a function of the throttle level (normalized), allowing a more realistic spin-down as a function of current power condition. A value of 1.0 implies that the engine will spin-down from MIL power to idle in 1 second, while a value of 0.1 implies that it will take 10 seconds to spin-down from MIL power to idle.
spin_down_table_mil_per_sec # throttle_level spin_down_per_sec 0.0 0.05 0.2 0.10 0.4 0.20 0.6 0.30 0.8 0.40 1.0 0.50 end_spin_down_table_mil_per_sec
- spin_down_ab_per_sec <real-value>¶
This defines how quickly the engine will “spool-down” as the power level is reduced. A value of 1.0 implies that the engine will spin-down from Full AB power to MIL power in 1 second, while a value of 0.1 implies that it will take 10 seconds to spin-down from Full AB power to MIL power.
- spin_down_table_ab_per_sec¶
This defines how quickly the engine will “spool-down” as the power level is reduced. Rather than a single value, this command uses a table that is a function of the throttle level (normalized), allowing a more realistic spin-down as a function of current power condition. A value of 1.0 implies that the engine will spin-down from Full AB power to MIL power in 1 second, while a value of 0.1 implies that it will take 10 seconds to spin-down from Full AB power to MIL power.
spin_down_table_ab_per_sec # throttle_level spin_down_per_sec 0.0 0.05 0.2 0.10 0.4 0.20 0.6 0.30 0.8 0.40 1.0 0.50 end_spin_down_table_ab_per_sec
- engine_smokes_above_power_setting <real-value>¶
This specifies the throttle level (MIL power) above which the engine will produce smoke. For example, a value of 0.8 will produce smoke when the throttle is above 80% power. If afterburner is selected, the smoke will cease. The default is a value of 1.0, which will not produce any smoke. This is useful for simulating engines that produce excessive smoke, such as old F-4 Phantoms and MiG-29s.
Return to SixDOF Thrust Producer Types, rigid_body_vehicle_type, point_mass_vehicle_type, or six_dof_object_types
Ramjet/Scramjet Engines¶
- ramjet … end_ramjet¶
Definitions for each type of ramjet engine are performed within the ramjet block.
ramjet // Thrust Specific Fuel Consumption (TSFC) tsfc_alt_mach_table ... end_tsfc_alt_mach_table // Thrust Table thrust_alt_mach_table ... end_thrust_alt_mach_table // Use afterburner appearance when operating afterburner_appearance_when_operating ... // Latch fuel injection control latch_fuel_injection ... // Use proportional throttle (rather than on/off throttle) use_proportional_throttle ... // Minimum thrust multiplier for proportional throttle minimum_proportional_thrust ... end_ramjet- tsfc_alt_mach_table¶
This specifies the thrust specific fuel consumption as a function of altitude and Mach in lbs-thrust/lbs-fuel/hr. Altitude units are feet.
tsfc_alt_mach_table irregular_table independent_variable alt units ft independent_variable mach precision float dependent_variable precision float alt 0.0 mach 1.90 2.00 2.50 2.6 values 1.96 1.96 1.96 1.96 ... alt 89000.0 mach 1.90 2.00 2.50 2.6 values 1.96 1.96 1.96 1.96 alt 90000.0 mach 1.90 2.00 2.50 2.6 values 1.96 1.96 1.96 1.96 end_irregular_table end_tsfc_alt_mach_table
- thrust_alt_mach_table¶
This specifies the thrust as a function of altitude and Mach in lbs. Altitude units are feet. Since the table will clamp rather than interpolate at the end values, it is important to ensure that data at the extreme points goes to zero values. Failure to do so could result in increasing thrust at high Mach, for example.
thrust_alt_mach_table_ irregular_table independent_variable alt units ft independent_variable mach precision float dependent_variable precision float alt 0.0 mach 1.90 2.00 2.50 2.6 values 0.0 10000.0 12000.0 0.0 ... alt 89000.0 mach 1.90 2.00 2.50 2.6 values 0.0 10000.0 12000.0 0.0 alt 90000.0 mach 1.90 2.00 2.50 2.6 values 0.0 0.0 0.0 0.0 end_irregular_table end_thrust_alt_mach_table_
- afterburner_appearance_when_operating <boolean-value>¶
This specifies whether or not an afterburner appearance should be used when the ramjet is operating. This only effects the appearance, it has no physical/kinematic effect. When true, and the ramjet is operating, it will have the same appearance of a jet engine using afterburner.
- latch_fuel_injection <boolean-value>¶
When true, the fuel injection will be latched (locked) into the on condition. This will keep the engine operating, regardless of throttle command, as long as fuel is available. When false, normal throttle control is used. The default value is false.
- use_proportional_throttle <boolean-value>¶
When true, a proportional throttle control will be used. When false, normal on/off throttle control is used. The default value is false.
- minimum_proportional_thrust <real-value>¶
This is the minimum thrust level that may be used for proportional throttle control. It is often 0.8, but must always be greater than zero. The default value is 0.0.
Return to SixDOF Thrust Producer Types, rigid_body_vehicle_type, point_mass_vehicle_type, or six_dof_object_types
Liquid-Propellant Rocket Engines¶
- liquid_propellant_rocket … end_liquid_propellant_rocket¶
Definitions for each type of liquid-propellant rocket engine are performed within the liquid_propellant_rocket block.
liquid_propellant_rocket // Max Thrust max_thrust_sealevel ... max_thrust_vacuum ... // Altitude Effects normalized_thrust_vs_alt ... end_normalized_thrust_vs_alt // Specific Impulse isp_vs_alt ... end_isp_vs_alt // Spin-up/Spin-Down normalized_spinup ... normalized_spindown ... // Smoke Trail Appearance When Burning creates_smoke_trail ... end_liquid_propellant_rocket- max_thrust_sealevel <force-value>¶
This specifies the maximum thrust that can be produced at sea level conditions. Either max_thrust_sealevel or max_thrust_vacuum should be specified, not both.
- max_thrust_vacuum <force-value>¶
This specifies the maximum thrust that can be produced at vacuum conditions. Either max_thrust_sealevel or max_thrust_vacuum should be specified, not both.
- normalized_thrust_vs_alt¶
This is a simple table of “normalized-thrust” versus altitude. Normalized thrust is a value that will be multiplied with a nominal isp-calculated thrust, typically computed using max_thrust_sealevel and isp_vs_alt. This allows altitude-effects on thrust production:
normalized_thrust_vs_alt #alt normalized_thrust 0.0 1.0 300000.0 1.0 end_normalized_thrust_vs_alt
- isp_vs_alt¶
This is a simple table of specific impulse (Isp) versus altitude:
isp_vs_alt #alt_feet Isp(sec) 0.0 285.0 100000.0 290.0 300000.0 295.0 end_isp_vs_alt
- normalized_spinup <real-value>¶
This specifies the spin-up rate in normalized-position/second. A value of 1.0 implies that the engine will spin-up from zero to full thrust in 1 second, while a value of 0.1 implies that it will take 10 seconds to spin-up from zero to full thrust.
- normalized_spindown <real-value>¶
This specifies the spin-down rate in normalized-position/second. A value of 1.0 implies that the engine will spin-down from full thrust to zero thrust in 1 second, while a value of 0.1 implies that it will take 10 seconds to spin-down from full thrust to zero thrust.
- creates_smoke_trail <boolean-value>¶
This determines whether or not the rocket will generate a smoke trail appearance. By default, liquid-propellant rockets do not produce a smoke trail, but solid-propellant rockets do produce a smoke trail.
Return to SixDOF Thrust Producer Types, rigid_body_vehicle_type, point_mass_vehicle_type, or six_dof_object_types
Solid-Propellant Rocket Motors¶
- solid_propellant_rocket … end_solid_propellant_rocket¶
Definitions for each type of solid-propellant rocket motor are performed within the solid_propellant_rocket block. Note that unlike jet engines, ramjets/scramjets, and liquid-propellant rocket engines, a solid-propellant rocket motor does not specify a fuel_feed, since it contains its own propellant properties.
solid_propellant_rocket // Thrust Parameters rated_thrust ... thrust_vs_time_sealevel ... end_thrust_vs_time_sealevel thrust_vs_time_vacuum ... end_thrust_vs_time_vacuum // Specific Impulse isp_vs_alt ... end_isp_vs_alt // Smoke Trail Appearance When Burning creates_smoke_trail ... end_solid_propellant_rocket- rated_thrust <force-value>¶
This specifies the “rated thrust” of the solid-propellant motor. Since thrust depends on a range of conditions, this is a reference number, often used to calculate percent thrust.
- thrust_vs_time_sealevel¶
This is a simple table of thrust in lbs as a function of time in seconds at sea level pressure conditions. Either thrust_vs_time_sealevel or thrust_vs_time_vacuum should be specified, but not both.
thrust_vs_time_sealevel #time thrust_lbs 0.0 0.0 0.1 2000.0 6.0 2000.0 6.5 200.0 end_thrust_vs_time_sealevel
- thrust_vs_time_vacuum¶
This is a simple table of thrust in lbs as a function of time in seconds at vacuum pressure conditions. Either thrust_vs_time_sealevel or thrust_vs_time_vacuum should be specified, but not both.
thrust_vs_time_vacuum #time thrust_lbs 0.0 0.0 0.1 2000.0 6.0 2000.0 6.5 200.0 end_thrust_vs_time_vacuum
- isp_vs_alt¶
This is a simple table of specific impulse (Isp) in seconds versus altitude in feet.
isp_vs_alt #alt_feet Isp(sec) 0.0 200.0 100000.0 200.0 300000.0 200.0 end_isp_vs_alt
- creates_smoke_trail <boolean-value>¶
This determines whether or not the rocket will generate a smoke trail appearance. By default, liquid-propellant rockets do not produce a smoke trail, but solid-propellant rockets do produce a smoke trail.
Updating Thrust Producer Definitions for AFSIM 2.9¶
In AFSIM 2.9, propellant mass and positioning were moved to the fuel_tank pattern.
- propellant_mass <mass-value>¶
This specified the propellant mass in the solid-propellant motor. The value here should be moved to the max_fuel_quantity and current_fuel_qty values of a fuel_tank created for the engine.
- propellant_rel_pos_x <length-value>¶
This specified the center of mass (in the x-direction of rocket-coordinates) of the propellant mass relative to the reference point of the rocket. To avoid changing the vehicle’s performance, the value here should be moved as-is to the cg_full_x and cg_empty_x values of a fuel_tank created for the engine. For more accuracy, this value may be added to the engine’s rel_pos_x value in migrating to cg_full_x and cg_empty_x.
- propellant_rel_pos_y <length-value>¶
This specified the center of mass (in the y-direction of rocket-coordinates) of the propellant mass relative to the reference point of the rocket. To avoid changing the vehicle’s performance, the value here should be moved as-is to the cg_full_y and cg_empty_y values of a fuel_tank created for the engine. For more accuracy, this value may be added to the engine’s rel_pos_y value in migrating to cg_full_y and cg_empty_y.
- propellant_rel_pos_z <length-value>¶
This specified the center of mass (in the z-direction of rocket-coordinates) of the propellant mass relative to the reference point of the rocket. To avoid changing the vehicle’s performance, the value here should be moved as-is to the cg_full_z and cg_empty_z values of a fuel_tank created for the engine. For more accuracy, this value may be added to the engine’s rel_pos_z value in migrating to cg_full_z and cg_empty_z.
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