简介：Thepitching-downflappingisanewtypeofbionicflapping,whichwasinventedbytheauthorbasedonpreviousstudiesontheaerodynamicmechanismsoffruitfly(pitching-up)flapping.ThemotivationofthisinventionistoimprovetheaerodynamiccharacteristicsofflappingMicroAirVehicles(MAVs).Inthispaperthepitching-downflappingisbrieflyintroduced.Themajorworksinclude:(1)Computingthepowerrequirementsofpitching-downflappinginthreemodes(advanced,symmetrical,delayed),whichwerecomparedwiththoseofpitching-upflapping;(2)Investigatingtheeffectsoftranslationalaccelerationtime,Δτ_t,androtationaltime,Δτ_r,attheendofastroke,andtheangleofattack,α,inthemiddleofastrokeontheaerodynamiccharacteristicsinsymmetricalmode;(3)Investigatingtheeffectofcamberonpitching-downflapping.Fromtheaboveworks,conclusionscanbedrawnthat:(1)Comparedwiththepitching-upflapping,thepitching-downflappingcangreatlyreducethetime-averagedpowerrequirements;(2)TheincreaseinΔτtandthedecreaseinΔτ_rcanincreaseboththeliftanddragcoefficients,butthetime-averagedratiooflifttodragchangesalittle.Andαhassignificanteffectontheaerodynamiccharacteristicsofthepitching-downflapping;(3)Thepositivecambercaneffectivelyincreasetheliftcoefficientandtheratiooflifttodrag.

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