ADAMS/Aircraft  

What's New

Improved balance simulation’s Hand-of-God movement, to meet the desired initial conditions

The Hand-of-God movement of the aircraft is unidirectional, replacing the previous whipping back and forth behavior. High accelerations associated with this whipping have effectively been eliminated. A new starting distance for each of the translational degrees of freedom is computed to minimize accelerations on the aircraft (full-aircraft test rig), landing gear (landing gear dynamics test rig), wheel (wheel test rig), and so on, in cases where no additional initial accelerations are specified.

Background and files_only options added to the simulation submittal dialog boxes

You can now submit simulations in the background. This allows you to continue using the interface while the analysis runs in the background. You must manually read in simulation results, but you can continue to use the interface for plotting, for example, while other simulations run in the background. The files_only option allows you to have the simulation files created but not actually submitted. You can then submit simulations for such files manually.

Table lookup mu-slip curve friction_mode option added to all ADAMS/Aircraft tire property files

You can now use custom mu-slip curves in the tire property files. An icon is also included (in the wheel modify dialog box in the Standard Interface) to view the mu-slip curve.

New AIR_CONSTANT_XY tire model added to ADAMS/Aircraft (not the ADAMS/Aircraft Handling Tire module)

A new tire model (and several sample <shared> tire property files) has been added to ADAMS/Aircraft. This new tire model uses a nonlinear vertical load-deflection table, like most of the ADAMS/Aircraft and ADAMS/Aircraft Handling Tire tire models. However, the tangential forces (Fx and Fy) are simply a function of the friction coefficient (mu_x and mu_y). These Fx and FY forces are ramped up over a user-specified time interval. Moment computations are via user-specified stiffnesses (Kx and Ky).

This tire model is useful for "cookbook" braking or lateral G turning analyses. The specified longitudinal or lateral forces are applied at the wheels, and the aircraft responds accordingly. Although unrealistic, the tire forces in this tire model are applied without regard to tire/ground slip behavior and the aircraft responds accordingly.

Simulation animations can be amusing. However, the desired aircraft lateral or longitudinal accelerations are achieved by selecting the proper friction coefficients.

New measurement request UDE entity

A new UDE type has been created that allows you to quickly create displacement, velocity, and/or acceleration measurement requests from existing hardpoints, construction frames, and/or markers. This entity also allows you to select whether or not such a measurement begins at the end of the balance simulation, when the actual follow-on simulation begins.

This entity is useful for creating output requests for Vertical Axle Travel, for example, when the measurement is to be referenced from a fully-extended strut position (which may not be the case prior to the balance simulation).

Lift force option added to landing gear drop simulation

In order to apply a lift-force profile during a drop simulation, you can now include a reference to a property file containing a table lookup of vertical force versus simulation time. An icon has also been added that allows you to manipulate such a curve in the Curve Manager.

Products of inertia added to the aircraft loading conditions file and input data table

You can now include products of inertia in the aircraft loading condition definition.

Total mass option added to the aircraft loading conditions file and to the input data table

You can now define the desired total vehicle mass in the aircraft loading condition definition. Previously, you could only specify the mass and inertia you wanted added to the assembly. With this new option, the mass and inertia increment needed to convert the original assembly mass/inertia to the input values is automatically calculated.

ADAMS/Aircraft’s hydraulics retract actuators now include volume flow rate output

Volume flow rate is now available for plotting, in session-specific volumetric flow rate units of length³/time.

Force/torque magnitudes are now included in the joint and bushing request entities

When you create new joint and bushing requests, force and torque magnitudes are also included in the automated request data.

Enhanced aggregate mass calculations

Enhanced aggregate mass calculations reported in the log file, and all automatic aircraft CG output is reported at the location of the computed aggregate mass, not necessarily at the CG you specified in the aircraft loading conditions.

Aggregate mass calculation output now includes aggregate mass moments of inertia. Also, aircraft CG displacement, velocity, and accelerations in the automatic request output (in the full-aircraft test rig) are now reported at the location of the aggregate mass, instead of at the incremental aircraft mass’ CG location specified in the aircraft loading conditions file.

CG altitude and CG ground communicators added to full-aircraft test rig

CG altitude is now included as part of the output communicators for the full-aircraft test rig. CG and ground reference plane location/orientation communicators have also been added. You can use this information to easily create solver variables, requests, construction frames, markers, and so on.

Issues resolved

36337
Simulation failure results in failure of entire analysis during sweeps of loading conditions and/or load cases.

New simulation submittal logic was implemented so that an unexpected failure in a single simulation, during a sweep of analysis simulations, would not result in the failure (or nonsubmittal) of the remaining simulations in the sweep.

37709
Running ‘ground’ or ‘taxi’ analyses result in failure if flex_body is set to ‘rigid’.
This is actually an ADAMS/Solver issue with the Save/Reload command, which is used in ADAMS/Aircraft’s ‘ground’ and ‘taxi’ simulations.

36930
Errors result when creating landing gear aero entity with a bushing reference.
This has been corrected and the landing gear aero entity can now have a joint or bushing reference.

36922
Most of the retract actuator entities did not save BuildStroke information in subsystem file. This has been fixed and BuildStroke is now saved as part of the subsystem file. BuildStroke is used in stroke request computations.

36914
When creating a rod-end or head-end actuator, error messages appeared for return_pressure variable. Eliminated source of the error.

30980
A space in the database parent directory name caused an error when referencing the road property file. Spaces in database parent directory name no longer result in error messages.

29120
Simulation dialog boxes now retain user-entered information. When you close a simulation dialog box and open it later in the same session, all of the previously entered information (except the output prefix) is displayed.

30907
Several UDEs (entities) function only with IPS units. All ADAMS/Aircraft entities should now function with any user-defined units. The default units for ADAMS/Aircraft are still IPS units, but you can change these units.

36946
User Vtorque entity creation is accompanied by errors. Source of the error has been fixed.

37741
Errors when importing STEP files using the browse method. The source of the error has been corrected.

36954
Creating a lg_var_fnsn_ude (variable filename-stringname entity) resulted in a hanging suppress_begin message. The source of the error has been corrected.

37299
Wheel analyses can take a long time to set up, prior to the actual simulation.

Source of this delay has been corrected. Wheel_spin_spline generated more quickly for commonly used velocity_free (spin_motion_mode) simulations.

36599
The constant damping coefficient damper entity has been fixed.
You may have noticed error or warning messages when you were creating a constant damping coefficient damper entity. The source of the error/warning has been fixed.

36576
The road was not placed in the correct location for a wheel analysis with Z-DOF mode of ‘force’. Source of the error has been eliminated.

38443
State variables in tire models (mainly alpha_lagged) were not driven back to zero when a tire left the ground.
Source of the error has been corrected. Alpha_lagged is now driven back to 0 with a time constant of 0.03333.

38726
The turnover calculation was incorrect for ground static attitude simulations that were conducted using results files (.res). The default for simulations involving assemblies without flexible bodies was for no results files to be written. However, if there were flexible bodies in the assembly, or if the MDI_ACAR_WRITE_RES environment variable was set to "yes" in the private or site configuration files (.acar.cfg), then results files would be written and the turnover calculation would, therefore, be incorrect. The problem has been corrected.

ADAMS/Aircraft Handling Tire
AIR_TRR64 ADAMS/Aircraft Handling Tire module now uses alpha_lagged instead of alpha. Alpha_lagged is computed using the yawed rolling 69brelaxation length, and this formula has been slightly modified to reduce solver integrator instability.

Known issues

Please go to the Knowledge Base to read all of the Known Issues for ADAMS/Aircraft 2003

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