This paper describes the development of a coupled rotor-flexible fuselage model which is suitable for simulating vibration reduction based on the active control of structural response (ACSR) approach. The rotor is an Nb-bladed aeroelastic model, with coupled flap-lag-torsional dynamics for each blade. Moderate blade deflections are included, together with complete coupling between rotor and fuselage dynamics. This aeroelastic response model is combined with a control algorithm based on an internal model principle. The control scheme effectively reduces vibrations to 0·05g levels or lower, using reasonable actuator forces. The baseline vibration levels in the fuselage are relatively high. This is due to the lack of damping modelling in the fuselage. With the actuators engaged, the hub loads remain virtually unchanged and therefore this control approach has no influence on vehicle airworthiness.

Low speed windtunnel measurements were made on a 50° delta wing with leading edge vortex flaps. Improvements in the lift/drag ratio were obtained by deflecting the leading edge vortex flap. Comparisons were made between the previously measured 60° and 70° delta wing results and the present 50° wing results. Improvements in the lift/drag ratio of the 50° delta wing were attained over a wider lift coefficient range than for the 70° delta wing. The highest lift/drag ratio for the 50° delta wing is achieved when the flow attaches to the flap surface without any large area of separation. Estimations of the aerodynamic forces were also made using a quasi-vortex lattice method coupled with the leading edge suction analogy for the 50°, 60° and 70° delta wings. The results obtained from this analysis agree qualitatively with the experimental results.

The implications of a rise in the pressure drag of a wing near its junction with a fuselage are examined. Based on some data measured for a swept-wing-plate junction, in which the wing was of NACA 0015-profile normal to its leading edge and swept back at 20°, it is found that there is a potential penalty of order 1% of the total aircraft drag in the cruise condition.

The transonic facility of DLR Göttingen (TWG) has been modernised with respect to an improved flow quality and flow simulation, as well as to the logistics of exchangeable test sections, operational reliability and productivity. It is presently equipped with a Laval nozzle for supersonic flow measurements, a perforated test section (6% open, 60° slanted holes) for transonic measurements, and a two-dimensional adaptive test section for subsonic measurements. The latter can perform two-dimensional adaptive tests on wing profiles, using the Cauchy integral formula for wall adaptation, as well as two-dimensional wall adaptation for three-dimensional models, utilising the Wedemeyer/Lamarche procedure, also known as the VKI method. For both cases, it is shown that the wall adaptation was successful. The 3D force results compare quite well to test results from the perforated test section, as well as to nominally interference-free results. The pressure distribution from the wing profile tests compare quite well to theoretical calculations. In the course of windtunnel modernisation, the transonic facility of DLR Göttingen has been equipped with the new software system DeAs for data acquisition and control of experimental facilities. In this environment the wall adaptation programs had to be implemented. Before adjusting the computed wall shape, it has to be controlled in the loop for sufficient accuracy and tolerable bending stresses. A simplified finite element method — also taking into account the pressure loads at the wall — is used for this purpose. The simplified approach has been checked against more detailed computations using ANSYS and NASTRAN.

The use of large scale windtunnel models offers considerable advantages to an experimenter

• 1. the possibility of obtaining high Reynolds number, certainly significant and sometimes equal to that in flight, for moderate stagnation pressures

• 2. an accurate representation of geometric elements, i.e. good form similitude (it is necessary to emphasise the importance of being very thorough in this area)

• 3. large internal volumes which enable numerous transducers to be implanted, ambitious experimental devices and means of remote control of model motorisation

• 4. test conditions remain those corresponding to industrial manufacturing methods and so avoid problems related to extreme miniaturisation.

Additionally, there exist some test conditions for which scale reduction is limited or even impossible; for example, because of physical phenomena, limitation in industrial methods of miniaturisation, or quite simply because the subject is itself the flying object. These conditions are applicable to all tests whether industrial or research. They are especially true for industrial tests where these concern important decisions. They are also true for research tests whenever they need to be sufficiently close to flight reality. Wind-tunnels are always a means to reduce the costs and risks of aeronautical project developments. The risk taken in extrapolating from windtunnel tests to flight are lower when the test is more realistic and this gives a clear advantage to tests on large sized models.

A windtunnel study was undertaken to determine the effectiveness of leading edge vortex plates in enhancing the lifting abilities of a blunt edged delta wing. In the investigation, vortex plates were attached to both the upper and lower surfaces of the leading edge. Various positions of the vortex plates with respect to the wing's leading edge were evaluated. The results indicate that a vortex plate located on the upper surface of the wing is capable of increasing lift so as to be comparable to a similar sharp edged wing, whilst reducing drag through some retained leading edge thrust. The increase in zero lift drag associated with vortex plate attachment tends to limit potential performance improvements. A vortex plate mounted on the lower wing surface decreased lift slightly compared to the blunt wing. However, drag was found to decrease markedly.