Engineering Model Documentation

Simulation Parameters

Input Units

— Determines the expected units of user inputs.

Output Units

— Determines the units of the output data.

Atmospheric Parameters Input Type

— Determines whether air properties come from the Standard Atmosphere at a given altitude or are entered directly.

Altitude*

— Altitude used to look up air properties from the Standard Atmosphere table.

Air Density*

— Air density.

• *Input visibility depends on selection for another input.

Propulsion System Parameters

Motor

— Selects the motor to analyze.

Propeller

— Selects the propeller to analyze.

Propulsion Data

Thrust

— Thrust produced by the propulsion system.

Current

— Current drawn by the propulsion system.

RPM

— Rotational speed of the propeller.

Motor Efficiency

— Efficiency of only the motor when attached to the propeller.

Propeller Efficiency

— Efficiency of only the propeller.

Total Efficiency

— Efficiency of the entire propulsion system.

• The file's first column is whichever variable was swept — airspeed at a fixed voltage, or voltage at a fixed airspeed.
• Rows outside the operating range are left out: a voltage outside the range the data covers, or an airspeed above the highest the data reaches at that voltage. The API applies the same cutoff.

Simulation Parameters

Input Units

— Determines the expected units of user inputs.

Output Units

— Determines the units of the output data.

Parasite Drag

— Determines whether to include user inputs for modeling parasite drag.

Airspeed

— Airspeed to evaluate the model at. Determines Reynolds number.

Atmospheric Parameters Input Type

— Determines whether air properties come from the Standard Atmosphere at a given altitude or are entered directly. Options are STD ATM and Custom.

Altitude*

— Altitude used to look up air properties from the Standard Atmosphere table.

Air Density*

— Air density.

Dynamic Viscosity*

— Dynamic viscosity of the air.

• *Input visibility depends on selection for another input.

Wing Parameters

Airfoil Input Format

— Determines whether airfoil geometry is selected from Aerodule’s catalog or uploaded via the user.

Airfoil

— Upload airfoil coordinates as a .dat or .txt file. The data should be in Selig format. You can find airfoil geometry at http://airfoiltools.com/ or https://m-selig.ae.illinois.edu/ads/coord_database.html

Wingspan

— Tip-to-tip span of the wing.

Root Chord

— Chord length at the wing root.

Tip Chord

— Chord length at the wing tip.

Wing Area

— Planform area of the wing.

Taper Ratio

— Ratio of tip chord to root chord length of the wing.

Aspect Ratio

— Equal to the wingspan squared divided by the planform area.

Sweep Reference

— The chordwise point that the wing sweep angle is measured from.

Sweep

— Wing sweep angle from the selected reference point.

Dihedral

— The upward angle of the surface from the horizontal when viewed from the front.

Tip Twist

— The difference in wing incidence from tip chord to root chord. Negative values create washout.

Wingtip Device Type

— Determines the wingtip geometry. Options are none, endplate, or winglet.

Height*

— Vertical length of the wingtip device.

Endplate Chord*

— Horizontal length of the endplate.

Winglet Sweep Reference*

— The chordwise point that the winglet sweep angle is measured from.

Winglet Sweep*

— Sweep angle of the winglet.

Winglet Taper Ratio*

— Ratio of winglet tip chord to root chord.

• *Input visibility depends on selection for another input.

Parasite Drag Analysis

Surface Roughness

— Characteristic roughness height of the wing and wingtip device surface.

CRUD Factor

— Parasitic drag multiplier used to account for miscellaneous drag not modeled.

Interference Factor*

— Parasite drag multiplier accounting for interference drag at the junctions with wingtip devices.

• Only with Parasite Drag included.
• *Input visibility depends on selection for another input.

Wing Geometry

Wing Area

— Planform area of the wing.

MAC

— Mean aerodynamic chord. The chord for a rectangular planform wing that would mirror the surface’s aerodynamic properties.

Aspect Ratio

— Equal to the wingspan squared divided by the planform area.

Taper Ratio

— Ratio of tip chord to root chord length of the wing.

• The rest of this file echoes the planform and airfoil that were entered, so it can be read back into the aircraft model.

Wing Aerodynamics

AOA

— Angle of attack.

CL

— Lift coefficient.

CD

— Drag coefficient.

CDi

— Induced drag coefficient.

CD0

— Parasitic drag coefficient.

CD_form

— Form drag coefficient. Accounts for pressure drag only.

CD_f

— Friction drag coefficient.

dCL/dα

— Lift-curve slope. The derivative representing the change in lift coefficient with respect to AOA.

CMm0

— Zero-lift pitching moment.

dCMl/dβ

— The derivative representing the change in rolling moment with respect to sideslip angle.

dCMn/dβ

— The derivative representing the change in yawing moment with respect to sideslip angle.

dCY/dβ

— The derivative representing the change in sideforce with respect to sideslip angle.

Root LE to AC

— Longitudinal location of the AC with respect to the root LE.

Not in an Output File

L/D

— Lift-to-drag ratio.

a_stall

— Stall AOA.

Simulation Parameters

Input Units

— Determines the expected units of user inputs.

Output Units

— Determines the units of the output data.

Fuselage**

— Determines whether to include user inputs for modeling fuselage effects on aircraft drag and stability.

Propwash & Propeller Effects

— Determines whether to include user inputs for propwash and propeller effects on tail effectiveness and aircraft stability.

Miscellaneous Drag

— Determines whether to include user inputs for modeling the effects of miscellaneous drag sources on aircraft drag and stability.

Parasite Drag

— Determines whether to include user inputs for modeling parasite drag.

Airspeed

— Airspeed to evaluate the model at. Determines Reynolds number.

Maximum Trim AOA

— Determines whether the model models the aircraft up to wing stall AOA, or a custom value. Options are Wing Stall AOA and Below Wing Stall AOA.

Custom Maximum Trim AOA*

— Sets the maximum AOA that the model will attempt to model aircraft trim up to. If this value is above the wing stall AOA, then it will default to the wing stall AOA.

Increase Tail Area to Allow Aircraft to Trim to Maximum AOA

— When selected, the model will increase the horizontal tail area so that the aircraft has enough tail authority to trim to the set maximum AOA. This is done only as a last resort, when the elevator/ruddervator has reached maximum deflection. In the case of a V-tail or A-tail, the total tail area will be increased and the tail angle modified such that yaw authority/stability is unchanged.

Atmospheric Parameters Input Type

— Determines whether air properties come from the Standard Atmosphere at a given altitude or are entered directly. Options are STD ATM and Custom.

Altitude*

— Altitude used to look up air properties from the Standard Atmosphere table.

Air Density*

— Air density.

Dynamic Viscosity*

— Dynamic viscosity of the air.

• *Input visibility depends on selection for another input.
• **Fuselage drag will not be modeled unless parasite drag is also modeled.

Wing Parameters

Aerodynamic Modeling Process

— Determines whether wing aerodynamic performance values are simulated by the model or uploaded into the model. Options are Simulate Wing Aerodynamics and Input Wing Aerodynamics.

Geometry Input Type

— Determines whether wing geometry is manually input or uploaded from an Aerodule wing geometry file. Options are Manual Entry and From File.

Wing Geometry File*

— Upload an Aerodule wing geometry type file to populate wing geometry.

Airfoil Input Format*

— Determines whether airfoil geometry is selected from Aerodule’s catalog or uploaded via the user.

Airfoil*

— Upload airfoil coordinates as a .dat or .txt file. The data should be in Selig format. You can find airfoil geometry at http://airfoiltools.com/ or https://m-selig.ae.illinois.edu/ads/coord_database.html

Wingspan*

— Tip-to-tip span of the wing.

Root Chord*

— Chord length at the wing root.

Tip Chord*

— Chord length at the wing tip.

Wing Area*

— Planform area of the wing.

Taper Ratio*

— Ratio of tip chord to root chord length of the wing.

Aspect Ratio*

— Equal to the wingspan squared divided by the planform area.

Sweep Reference*

— The chordwise point that the wing sweep angle is measured from.

Sweep*

— Wing sweep angle from the selected reference point.

Dihedral*

— The upward angle of the surface from the horizontal when viewed from the front.

Tip Twist*

— The difference in wing incidence from tip chord to root chord. Negative values create washout.

Wingtip Device Type*

— Determines the wingtip geometry. Options are none, endplate, or winglet.

Height*

— Vertical length of the wingtip device.

Endplate Chord*

— Horizontal length of the endplate.

Winglet Sweep Reference*

— The chordwise point that the winglet sweep angle is measured from.

Winglet Sweep*

— Sweep angle of the winglet.

Winglet Taper Ratio*

— Ratio of winglet tip chord to root chord.

Surface Roughness*

— Characteristic roughness height of the wing and wingtip device surface.

Aerodynamics Input Type*

— Determines whether wing aerodynamic properties are manually input or uploaded from an Aerodule wing aerodynamics file. Options are Manual Entry and From File.

Wing Aerodynamics File*

— Upload an Aerodule wing aerodynamics type file to populate wing aerodynamics.

Wing Polar Data*

— An excel file or .txt (Tab Delimited) file with the lift and drag coefficients of the surface over an AOA range. FORMATTING INSTRUCTIONS: Each row should represent data at a unique AOA, ordered from low AOA at the top to high AOA at the bottom. The first column should be AOA, the second column CL, and the third column CD. The fourth and fifth columns are optional and can be CDi and CD0 respectively. If included, they will be used to apply the user input interference and CRUD factor to the surface’s parasitic drag values. If both columns are not completely filled out, they will be ignored.

Root LE to AC*

— Longitudinal location of the AC with respect to the root LE.

CMm0*

— Pitching moment coefficient at zero lift.

dCMl/dβ*

— Change in wing rolling moment coefficient with respect to sideslip. Also defined as the wing lateral static stability derivative.

dCY/dβ*

— Change in side force coefficient with respect to sideslip.

CRUD Factor*

— Parasitic drag multiplier used to account for miscellaneous drag not modeled.

Interference Factor*

— Parasite drag multiplier accounting for interference drag at the junctions with any wingtip devices and the fuselage.

CG to Wing AC

— Longitudinal location of the wing AC with respect to the aircraft CG.

Wing AC Z from CG

— Vertical location of the wing AC with respect to the aircraft CG.

Incidence

— AOA that the wing is mounted with respect to the aircraft.

• *Input visibility depends on selection for another input.

Tail Parameters

Tail Configuration

— Determines the modeled tail configuration. Options are Conventional / Cruciform, T-tail, V-tail, A-tail, U-tail, Inverted U-tail, and H-tail.

(HT | VT | Tail) Aerodynamic Modeling Process

— Determines whether tail aerodynamic performance values are simulated by the model or uploaded into the model. This option is presented for the HT and VT or Tail when applicable. Options are Simulate Tail Aerodynamics and Input Tail Aerodynamics.

(HT | VT | Tail) Airfoil Input Format*

— Determines whether airfoil geometry is selected from Aerodule’s catalog or uploaded via the user.

(HT | VT | Tail) Airfoil*

— Upload airfoil coordinates as a .dat or .txt file. The data should be in Selig format. You can find airfoil geometry at http://airfoiltools.com/ or https://m-selig.ae.illinois.edu/ads/coord_database.html This option is presented for the HT and VT or Tail when applicable.

Taper Ratio

— Ratio of tip chord to root chord length of the tail.

Aspect Ratio

— Equal to the tail span squared divided by the planform area.

Sweep Reference

— The chordwise point that the tail sweep angle is measured from.

Sweep

— Tail sweep angle from the selected reference point.

Tail Arm*

— Longitudinal location of the tail AC with respect to the aircraft CG.

(HT | VT | Tail) Sizing Method*

— Method used to determine the planform area of the tail. Options are Static Stability Coefficient, Volume Coefficient, and Area.

Longitudinal Static Stability Coefficient*

— The static stability coefficient that the tail is sized to achieve.

HT Volume Coefficient*

— The tail volume coefficient that the tail is sized to achieve.

HT Area*

— The planform tail area.

Root Z from CG*

— Vertical location of the tail root chord with respect to the aircraft CG.

(HT | Tail) Incidence

— AOA that the tail is mounted with respect to the aircraft.

CD0*

— Drag coefficient of the VT when aligned with the flow. Also defined as the VT parasitic drag coefficient.

Spanwise MAC Location*

— The spanwise distance from the root chord to the MAC.

Root LE to AC*

— Longitudinal location of the AC with respect to the root LE.

(HT | Tail) Polar Data*

— An excel file or .txt (Tab Delimited) file with the lift and drag coefficients of the surface over an AOA range. FORMATTING INSTRUCTIONS: Each row should represent data at a unique AOA, ordered from low AOA at the top to high AOA at the bottom. The first column should be AOA, the second column CL, and the third column CD. The fourth and fifth columns are optional and can be CDi and CD0 respectively. If included, they will be used to apply the user input interference and CRUD factor to the surface’s parasitic drag values. If both columns are not completely filled out, they will be ignored. In the case of a v-tail or a-tail, the uploaded polar should be for a flat surface. The model will add dihedral to the surface and properly scale the lift and drag coefficients based on dihedral.

CMm0*

— Pitching moment coefficient at zero lift.

dCY/dβ*

— Change in side force coefficient with respect to sideslip.

Dihedral*

— The upward angle of the surface from the horizontal when viewed from the front.

Elevator-Chord Ratio

— Ratio of the elevator chord to the tail MAC.

Maximum Elevator Deflection

— Maximum angle that the elevator can deflect in either direction. The total elevator range of motion is twice this value.

Surface Roughness*

— Characteristic roughness height of the tail surface.

CRUD Factor*

— Parasitic drag multiplier used to account for miscellaneous drag not modeled.

Interference Factor*

— Parasite drag multiplier accounting for interference drag at the junctions with tail surfaces and the fuselage.

• *Input visibility depends on selection for another input.

Fuselage Parameters

Nose / Center / Tail Section Length*

— Longitudinal length of each fuselage section.

Nose / Center / Tail Section Angle*

— Angle of the centerline of each section with respect to the horizontal plane.

Nose to CG*

— Longitudinal location of the aircraft CG with respect to the fuselage nose.

FWD Center Diameter*

— Diameter at the forward end of the fuselage center section. Also equal to the diameter of the aft end of the fuselage nose section.

Aft Center Diameter*

— Diameter at the aft end of the fuselage center section. Also equal to the diameter of the forward end of the fuselage tail section.

Surface Roughness*

— Characteristic roughness height of the fuselage surface.

Interference Factor*

— Parasite drag multiplier accounting for interference drag at the junctions with the wings, tail, etc.

CRUD Factor*

— Parasitic drag multiplier used to account for miscellaneous drag not modeled.

• *Input visibility depends on selection for another input.

Propeller Parameters

Propeller Diameter*

— Diameter of each propeller.

Number of Motors*

— Number of each motor / propeller set on the aircraft.

Blades per Propeller*

— Number of blades on each propeller.

Thrust at Reference Airspeed*

— Thrust per propeller at the reference airspeed.

Propeller Hub to CG*

— Longitudinal location of the propeller hub with respect to the aircraft CG. Positive is aft of the CG.

Propeller Hub Z from CG*

— Vertical location of the propeller hub with respect to the aircraft CG.

HT Propwash Blanket Ratio*

— Fraction of the horizontal tail area immersed in the propeller slipstream.

VT Propwash Blanket Ratio*

— Fraction of the vertical tail area immersed in the propeller slipstream.

• *Input visibility depends on selection for another input.

Miscellaneous Drag & Moment Parameters

CD*

— Drag coefficient of the misc. drag source.

Reference Area*

— Reference area for the drag coefficient of the misc. drag source.

Z from CG*

— Vertical location of the misc. drag source with respect to the aircraft CG.

Nacelle CRUD Factor*

— Parasitic drag multiplier used to account for miscellaneous drag not modeled.

Length*

— Length of the nacelle.

Diameter*

— Maximum diameter of the nacelle.

Surface Roughness*

— Characteristic roughness height of the nacelle surface.

Interference Factor*

— Parasite drag multiplier accounting for interference drag between the nacelle and any surrounding objects.

• *Input visibility depends on selection for another input.

Tail Geometry

HT Area

— Planform area of the horizontal tail.

VT Area

— Planform area of the vertical tail.

HT MAC

— Mean aerodynamic chord of the horizontal tail. The chord for a rectangular planform surface that would mirror the horizontal tail’s aerodynamic properties.

VT MAC

— Mean aerodynamic chord of the vertical tail. The chord for a rectangular planform surface that would mirror the vertical tail’s aerodynamic properties.

HT Span

— Tip-to-tip span of the horizontal tail.

VT Span

— Root-to-tip span of the vertical tail.

HT Root Chord

— Chord length at the horizontal tail root.

HT Tip Chord

— Chord length at the horizontal tail tip.

VT Root Chord

— Chord length at the vertical tail root.

VT Tip Chord

— Chord length at the vertical tail tip.

HT Dihedral

— The upward angle of the horizontal tail from the horizontal when viewed from the front.

HT Root LE to HT AC

— Longitudinal location of the horizontal tail AC with respect to its root LE.

VT Root LE to VT AC

— Longitudinal location of the vertical tail AC with respect to its root LE.

• On a V-tail or A-tail the one canted panel is reported under HT, and its cant angle is written into HT Dihedral.
• The rest of this file echoes the tail aspect ratios, tapers, sweeps and airfoils that were entered.

Aircraft Aerodynamics

AOA

— Angle of attack.

CL

— Lift coefficient.

CD

— Drag coefficient.

CD_wing

— The total wing drag coefficient.

CD_fus

— The total fuselage drag coefficient.

CD_HT

— The total HT drag coefficient.

CD_VT

— The total VT drag coefficient.

CD_trim

— The drag coefficient associated with deflected control surfaces required for trimmed flight.

CD_nac

— The total nacelle drag coefficient.

CD_misc

— The total drag coefficient associated with miscellaneous drag sources.

dCMl/dβ

— The derivative representing the change in rolling moment with respect to sideslip angle.

dCMm/dα

— The derivative representing the change in pitching moment with respect to AOA.

dCMn/dβ

— The derivative representing the change in yawing moment with respect to sideslip angle.

SM

— The MAC normalized distance from the aircraft CG to the aircraft NP.

NP

— The longitudinal point on the aircraft where all aerodynamic forces act about. This location is measured from the aircraft CG.

Not in an Output File

L/D

— Lift-to-drag ratio.

Swet_fus

— Fuselage wetted area. Also defined as the fuselage outer surface area.

theta_tail

— The angle of a V-tail or A-tail panel from the horizontal when viewed from the front.

de_trim

— Elevator (or ruddervator) deflection. Positive values indicate the control surface is deflected upwards.

HT Propwash Coefficient

— The factor of increased HT effectiveness due to propwash.

VT Propwash Coefficient

— The factor of increased VT effectiveness due to propwash.