Aircraft Design & Certification

Load assumptions

AIRLET II - Aircraft Loads Evaluation Tool II

Obtaining reliable load assumptions is an important step in developing a new product. Considering certification, we have developed a tool that produces loads including both aerodynamic and component loads, while focusing on a specific certification basis.

This allows us to avoid unnecessarily conservative load estimates, while not overlooking any certification related requirement yielding reliable load assumptions.

Airlet II is a new, in-house flight test validated software tool designed to quickly and accurately predict aerodynamic and inertial loads for aircraft of any configuration. A proven analysis strategy was used that allows for speedy load predictions without sacrificing accuracy. Some of the main features of Airlet II include aerodynamic and inertial load prediction, control effectiveness analysis, stability analysis and load export to finite element analysis programs. Both pre and post stall analysis is supported.:

  • Aerodynamic loads (Vortex Lattice, EASA CS-Code)
  • Mass reaction loads (EASA CS Code)
  • External (ground) loads (EASA CS-Code)
  • Structure interface loads.
  • Data output to structure analysis software (i.e. FEMAP)

Aerodynamics solver
Airlet II features an aerodynamics solver that couples 2d airfoil viscous flow analysis with 3d aerodynamics for a fast and reliable solution capable of rapid pre and post stall analysis of almost any aircraft configuration imaginable.

  • Supports any number of wing surfaces
  • Simulates control deflections
  • Post-stall influence
  • Downwash and wake modeling
  • Handles both conventional and unconventional aircraft configurations
  • Calculate pressure distributions at any point on any wing surface
  • Calculate control hinge moments

Picture1AIRLET 747

Load Analysis

  • The load analysis tool set includes tools for quick and reliable estimation of load cases applicable for aircraft certification programs.
  • Determine coupled aerodynamic and mass reaction loads
  • Determine accumulated section forces and moments for structural sizing and test planning
  • Systematic evaluation of CS-22, CS-23, CS-VLA, and CS-LSA load cases
  • Identification of critical load cases

Other Applications

  • Static stability
    • Check for adequate control authority in all corners of the flight envelope
    • Predict the influence of one flight surface on another both pre and post stall
    • Predict safe CG envelope
  • Flight dynamics
    • Predict aircraft response and the associated loads to control inputs
    • Calculate aircraft handling quality parameters

In the business of aircraft certification, time is a valuable asset

Any certification project involves several time consuming stages. One of these is the determination of the loads acting on the aircraft. These loads, defined by rules set by the aviation authorities, differ for each project and are therefore re-determined for each new aircraft type.

AIRLET, the Aircraft Load Evaluation Tool engineered by AD&C, is a software tool developed to determine these loads.

Load assumptions Loaddefs

Provide the tool with the preliminary geometric and mass data of the aircraft, and it returns list of loads for all the applicable load cases. In doing so, it saves a considerable amount of valuable time during these first steps towards certification.

AirletII architecture


Funded by

Bundesministerium für Wirtschaft und Technologie Zentrales Innovationsprogramm Mittelstand

following a decision of the German Bundestag

From Concept

to Certification.

Contact us!