The cost and time relative to model building could be reduced considerably by the introduction of additive manufacturing. To evaluate the feasibility of the technique to build practical models, a real fighter was adopted as the prototype and a resin-metal hybrid model fully deployed with control surfaces was designed, validated, and tested in the paper. Connection structures that can ensure reliable connections and enable angle adjustment of control surfaces were designed in detail. Based on a careful worst-case analysis from computational fluid dynamics calculations, finite element analysis analyses for strength and stiffness validations were conducted, which shows the safety of the model in testing. First eigenfrequencies of the hybrid model and the metal model were calculated with the FEA method, and the comparison indicates resonance clearance improvement of the hybrid model duo to a remarkable weight reduction by nearly 50% to the metal one. Most aerodynamic coefficients of the hybrid model obtained from wind-tunnel testing are consistent with those of the metal model, from which it can be concluded that the hybrid model can replace metal models in the aerodynamic study for aircraft in the subsonic domain. The efficiency to build models was also improved significantly.

Based on rapid prototyping,the paper puts forward a rapidly fabrication technique for wind-tunnel models of flight vehicles.The rapidly fabrication technique of integral tap-passage pressure models was developed,deriving from the study of dimensional compensation,taps and passages design and passage configuration design.Focusing on the design and fabrication of structurally similar aeroelastic models,a new method is presented in the paper and validated by modal test.The authors developed a fabrication technique for the fabrication of wind-tunnel models made of metal-resin composite,through the combination of rapid prototyping and electrochemical deposition.The time and cost advantages of the new technique is discussed,too.In summary,overcoming the limitation of traditional fabrication techniques,the rapidly fabrication technique provides a basis of the development of new test techniques.

A method for designing photosensitive resin wind tunnel model considering elastic deformation is presented to reduce the effect of model deformation caused by low stiffness of photosensitive resin on aerodynamic force experiment data in wind tunnel.Numerical calculation method for aeroelasticity is used to predict the model deformation under aerodynamic force and the original model shape is modified on the basis of the numerically calculated deformation,thereby the manufacture shape of resin model is obtained,so that the shape of model after deformation under aerodynamic force is same as the original model shape,thus eliminating the effect of photosensitive resin elastic deformation.Six F4 model manufacture shapes are designed on the basis of this method and the hypothesis that the airfoil of large aspect ratio wing is rigid.Six models are manufactured by using rapid prototyping equipment and tested in FL-21 transonic wind tunnel.Test data show that at design point,lift coefficients CL of 4#,5# and 6# models are in good agreement with the data of three foreign wind tunnels,and so are the pitch moment coefficients Cmy of 1#,2#,3# and 5# models;at off-design points,CL and Cmy are quite different from the foreign data;drag coefficients Cd are greater than foreign wind tunnel results because of Reynolds number Re difference between this test and foreign wind tunnel tests.So,at design point,this method can obviously improve the aerodynamic force data precision of photosensitive resin wind tunnel model.

In order to overcome the difficulties with machining the internal channels of a wind tunnel aircraft model for pressure measurements,this paper proposes the use of stereolithography to realize the integrated forming of aerodynamic configurations and internal channels.A series of micro-channels with different diameters and lengths are fabricated,and their forming qualities are examined with an optical microscope system.The diameters of cross-sections are also measured to conform with the radius compensation principle concerning the parameters such as diameter,length and prototyping direction.Air tightness and air permeability of the micro-channels is verified by means of a special test device.Therefore,the channels based on stereolithography meet the requirements of wind tunnel test and they are able to replace the metal tubes.

PurposeThe purpose of this paper is to present a novel method to design and fabricate aeroelastic wing models for wind tunnel tests based on stereolithography (SL). This method can ensure the structural similarity of both external and internal structures between models and prototypes.Design/methodology/approachAn aluminum wing‐box was selected as the prototype, and its natural modes were studied by FEA and scaled down to obtain the desired dynamic behavior data. According to similarity laws, the structurally similar model was designed through a sequential design procedure of dimensional scaling, stiffness optimization and mass optimization. An SL model was then fabricated, and its actual natural modes was tested and compared with the desired data of the prototype.FindingsThe first two natural frequencies of the model presented strong correlation with the desired data of the prototype. Both the external and internal structures of the model matched the prototype closely. The SL‐based method can significantly reduce the total mass and simplify the locating operations of balance‐weights. The cost and time for the fabrication were reduced significantly.Research limitations/implicationsFurther investigation into the material properties of SL resins including stiffness and damping behaviors due to layered process is recommended toward higher prediction accuracy. Wind tunnel tests are needed to study the in situ performance and durability of SL models.Originality/valueAlthough the paper takes a wing‐box as the study object, structurally similar SL models of entire wings can be obtained conveniently, benefiting from the low‐stiffness material properties of SL resins and the fabrication capacity to build complex structures of SL process. This paper enhances the versatility of using SL and other rapid prototyping processes to fabricate models to predict aeroelastic characteristics of aircraft.