Aerodynamic testing of missiles is a standard activity in DNW’s wind tunnels. Missiles have specific requirements and challenges due to typical characteristics such as slender configurations with slender wings and fins, extremely high angles of attack and arbitrary roll angles, transonic and supersonic speeds and complex, vortex-dominated interference between configuration components and hysteresis effects.
Test objectives
Despite the variety and peculiarities of missiles, their aerodynamic test objectives are similar to those of most other airborne vehicles:
|
-
|
Integral forces and moments
|
|
-
|
Stability features
|
|
-
|
Control surface effectiveness
|
|
-
|
Hinge moments and loads
|
|
-
|
Boat tail and nozzle drag
|
|
-
|
(Unsteady) flow characteristics
|
|
-
|
Deployable wings and/or fins
|
|
-
|
Rolling and maneuver simulation
|
|
-
|
Fluid structure interaction
|
In addition, DNW is often involved in tests and measurements that focus on new developments such as unconventional geometries, interference effects during launch from weapon bays or carrier vehicles, munitions deployment, stealth (radar cross section), jet and plasma control, smart materials, etcetera. New trends in missile aerodynamics include:
|
-
|
Integration of air intakes and coolers
|
|
-
|
Thrust drag bookkeeping
|
|
-
|
High angle of attack aerodynamics
|
|
-
|
Flow field surveys
|
|
-
|
Effectiveness of lateral control jets
|
|
-
|
Non circular body aerodynamics
|
|
-
|
Optimization of RCS contours
|
|
-
|
Effect of pyrotechnical controls
|
Simulation aspects
Although missiles pass the low-speed range during launch and acceleration, tests on their aerodynamic features are mainly carried out in DNW’s transonic and supersonic wind tunnels: HST, TWG, SST and RWG. Selection of the tunnel to be used depends on the different test section sizes, pressure ranges, operation modes and the Reynolds numbers that need to be realized. Cost aspects also affect the final decision.
The Reynolds number for missiles is often based on the body diameter, which typically is in the range of 5% of the test section diameter. This is the reason why this value was used as reference length in the Reynolds-Mach diagram.
High angles of attack and arbitrary roll angles are mandatory for missile testing. This is realized through a combination of the standard α-sword supports and roll angle devices with remote-controlled, specialized flexible knee and cranked roll adapters.
Highly maneuverable missiles require extensive testing of unsteady loads. DNW performed a large number of tests on rolling missiles (forced and free-to-roll, oscillatory and transient motion).
Measurement techniques and equipment
Missile testing involves the complete range of conventional and advanced measurement techniques available at DNW.
|
-
|
Forces (static and dynamic): DNW’s facilities for force measurements include a large number of internal and component balances that are well-suited for missiles (load range, dimension, stiffness).
|
|
-
|
Pressures: As fins and control surfaces are extremely thin in certain cases, conventional pressure tube techniques need to be replaced or supplemented by PSP. This also helps to determine loads and control forces.
|
|
-
|
Flow visualization: Classic techniques such as oil flow, mini tuft, acenapthen and schlieren are supplemented by advanced methods such as laser light sheet.
|
|
-
|
Quantitative optical techniques: Techniques such as PSP, PIV, infrared and TSP thermography are frequently used to analyze and optimize the aerodynamic interferences between missile components (body, wings, fins, strakes).
|
Scope of services
|
-
|
Consultancy with respect to simulation, scaling and sizing of missile models and adaptation of air intakes
|
|
-
|
Comprehensive DNW wide and facility imposed test project management with a single point of contact
|
|
-
|
Provision of modern measurement techniques and instrumentation such as PSP, infrared imaging and flow visualization (PIV)
|
|
-
|
Provision of balances (internal and external)
|
|
-
|
Measurement quality control by means of online data acquisition and processing and display of test data during the test
|
|
-
|
Offline data processing, formatting and secure data transmission to users all over the globe
|
|
-
|
Post test evaluation by an expert team, combined with data analysis and interpretation (upon request)
|