BODY RESISTANCE 83 



It is doubtful whether there is much shielding between two 

 or more cockpits in tandem : no allowance should therefore be 

 made, but each cockpit should be taken at full value. 



Windscreens are not included in the above. 



Radiators. If a is the total frontal area of the radiator in 

 square feet, the resistance is given in the following table : 



The above figures apply to standard honeycomb radiators 

 with 10 millimetre by 120 millimetre tubes. 

 r :. Flat Plates. Under this heading come such items as 

 windscreens, backs of steps of floats and flying boat hulls, backs 

 of louvres used for cooling engine bays, parts of fittings project- 

 ing normal to the wind, and many small miscellaneous parts. 



First, all such parts are to be grouped together and their 

 aggregate frontal area a in square feet for the complete machine 

 noted, no allowance being made for any shielding which may 

 occur. Then the value of r for these items is given by the 

 formula 



r = 2Qa. 



Circular Cylinders. Under this heading are included pro- 

 jecting heads of engine cylinders, wheel axles if unfaired, and 

 sometimes various other odds and ends. 



First obtain the aggregate frontal area a in square feet of all 

 such parts. Then 



r = 310. 



Line of Action of Body Resistance. The height of this 

 line of action is required in certain cases. To find it, first group 

 the items of R in batches corresponding to parts at the same 

 vertical level. Usually these batches will be (i) Gap struts, 

 flying wires, antiflying wires and incidence wires, all reckoned as 

 being at a point half way up the gap ; (2) Axle and wheels, 

 reckoned at the level of the wheel centre ; (3) Remainder of 

 chassis, reckoned as halfway between the wheel centre and the 

 bottom of the fuselage ; (4) The fuselage and all items not in- 

 cluded elsewhere, half way up the fuselage at the centre section 



