We make some crucial remarks about the recent presentation by Griffiths et al. considering their anomalous experimental results: The ball spin was observed to occasionally increase with time during its flight through the air. Possible reasoning due to experimental set-up and autorotation were given. Our results will be useful to sport education and relevant researchers.
CuervaASanz-AndrésAMeseguerJ, et al. An engineering modification of the blade element momentum equation for vertical descent: an autorotation case study. J Amer Helicopter Soc2006; 51: 349–354.
2.
CrossRLindseyC.Measurements of drag and lift on smooth balls in flight. European J Phys2017; 38: 044002.
3.
GriffithsIEvansCGriffithsN.Tracking the flight of a spinning football in three dimensions. Meas Sci Technol2005; 16: 2056–2065.
4.
KonishiYOkuizumiHOhnoT.PIV measurement of a flying table tennis ball. Proc Eng2016; 147: 104–109.
5.
SeifertJ.A review of the Magnus effect in aeronautics. Prog Aerosp Sci2012; 55: 17–45.
6.
LugtHJ.Autorotation. Ann Rev Fluid Mech1983; 15: 123–147.
7.
RiabouchinskyDP.Thirty years of theoretical and experimental research in fluid mechanics. J Royal Aeronaut Soc1935; 39: 282–348, 377.
8.
LafayMA.Sur l’inversion du phénomène de Magnus. Comptes Rendus Hebdomadaires Des Séances1910; 151: 867–868.
9.
KrayTFrankeJFrankW.Magnus effect on a rotating sphere at high Reynolds numbers. J Wind Eng Ind Aerodyn2012; 110: 1–9.
