DR WATTS, in introducing Captain Barnwell, said I am sure we are all very muchindebted to Captain Barnwell for giving us the benefit of his knowledge andexperience The subject cannot fail to be interesting to all who are associatedwith aricraft design, although the attitude of aircraft designers generallyvaries between two extremes On the one hand there are some who consider airscrewdesign as something mysterious, to be left to an outside expert, and on theother hand there are some who consider it so simple that it can safely be leftto an internal subordinate It is quite common knowledge that Captain Barnwelladopts the happy medium, and deals with the subject himself

I remember that 14 or 15 years ago, at the old British and Colonial AeroplaneCompany, Captain Barnwell was designing a special “hush-hush”machine I was a mere nobody in the drawing office, entrusted with airscrewdesign, but I remember that Captain Barnwell designed his own airscrew for this“hush-hush” machine, much to my secret chagrin So behind thispaper there is 14 or 15 years of personal knowledge of airscrew design