ABSTRACTMicro air vehicles “MAV” belong to a class of aircrafts currentlywith a maximum size of 300mm and are capable of operating atspeeds of not less than 12m/s. MAV’s are expected to findapplications in border patrol, visual surveillance etc. MAV’s aretypically characterized by a low aspect ratio wing operating atlow Reynoldss numbers (10^5 ~ 10^6). A camber plate MAV of300mm wing span generates cl of 0.7-0.8, comparatively blendedwing MAV generates cl of 1-1.3 this motivates the work to becarried out. This work contains the aerodynamic design, airframemodeling, production and development of a blended wing MAV.
WHAT IS BLENDED WING BODY?Blended Wing Body (BWB) aircraft have a flattened and airfoil shaped body, which produces most of the lift, the wings contributing the balance.BWB incorporates design features from both a futuristic fuselage and flying wing design.
ADVANTAGESBlended wing body has lift-to-drag ratio 50% greater than conventional airplane.Efficient high-lift wings and a wide airfoil- shaped body.
Its fuel burn will be 27% lower than its conventional Airbus. Take off weight 15% lower. Empty weight will be 12% less. It will only require three instead of four engines, and will match or exceed conventional performance, despite having 27% less thrust.
It is lighter.More fuel efficient.Requires far less power.More aesthetic in appearance.
HISTORY ABOUT BLENDED WING CONFIGURATIONStout Batwing first blended wingconfiguration… in 1926
Micro Air Vehicles (MAV) Micro air vehicles belong to a class of aircraft currently designated with a class of size 300mm and are capable of operating at speeds of not less than 12m/s.They are typically characterized by low aspect ratio.
MAV’s are a class of small light-weight aircrafts designed to operate in situations that are practically unsuitable for large aircrafts.MAV’s are used for battlefield reconnaissance, visual surveillance, border patrol, air sampling for civil services.
STEPS INVOLVED IN DEVELOPMENT OF A BLENDED WING BODY AIRCRAFT (MAV)
AERODYNAMIC STUDIESThe aerodynamics of the aircraft is greatly affected by airfoil, operating chord based Reynolds number, plan form shape and wingtip devices like winglets.
AIRFOIL SELECTION AND ANALYSISThe number of airfoils are referred from various technical papers.Performance studies on number of aircrafts indicated that GM78, J5012, MH45 are the three airfoils having better performance and meets the requirements of Blended wing MAV.
AIRFOIL AOA Cl/Cd Cl GM78 7° 70% 1.2 J5012 7° 55% 0.7 MH45 7° 70% 1.0This comparison of aerodynamicperformances shows that the GM78 is the bestsuitable airfoil for a blended wing aircrafts.After that selection analysis is to be done.
PLANFORM DESIGNChosen plan form designs are Fig.1 Fig.2 Fig.3
After the comparison of the performanceanalysis of the three plan forms the inverseZimmerman plan form (fig.3) is chosen to bethe best.With and without winglet the graph of Cl and αis
STABILITY AND WINGLETSDirectional stability is associated with angular motion about the z-axis.Vertical wing is the conventional mechanism for directional stability.Winglets with 90° can help to reduce the induced drag.Winglet sizing is done by vertical tail volume coefficient.
AIRFRAME AND SKIN PRODUCTION FINAL ASSEMBLY AND FINAL TEST Airframe is a skeleton of MAV and is prepared by the composites of Kevlar and Rohacell.Using a technique named rapid prototyping is used in the mechanism of skin material.Blended wing model is prepared for testing.