J'AKIXG OJ.'F OF AKKOPLAXKS. 239 



ilie thrust is . Resistance = yv' d o". 



'b 



- -K (J r = 1' 7- • (1) 



y g (h ^ 



To find K, we will assume that the machine in the tail-up 

 position is in the attitude for level flight, for which tho 

 air speed is I ft. /sec. 



Tlien ' ,/ 550 P ^. , ,., 



dv 

 1/ 550 P (1 - rV/-') = mUj V- ~f^ ■ 



This leads to 



</. >]. 550. P \3. 

 0.1308 r-' , 



Where T' = level speed in miles per hour. 



F„ = iiiiiiiiiii^mi^ flying speed in miles per hour. 

 J^J = horse power per 1,000 Ihs. 

 In this formula, T" and E both diminish with diminishing- 

 density, but the change of T' is small compared with that 

 of E. T'„, on the other hand, increases as the density gets 



1 

 less, being' proportional to ^= 



s/d. 



AVhen 1 „ =1 , /.('., at the ceiling, the leng'th of run 

 becomes infinita. 



III. Ari'LICATION TO THE " SlLVEU QUEEN II." 



(Yickers-Vimy Machine. ) 



The weiglit of the Vickers-Yimy machine, Mithout load, 

 is only known to me when the engines were Sunbeam Morris. 

 The diflerence in weight of these engines from that of the 

 Holls-Royce Eagle VIII. is known, and the weight I have 

 takeji cannot be far from correct. 



I have taken two loadings, as follows: — 



Machine, light ... ... ... 0,900 



Fuel and oil ... ... ... 1,200 



Crew and accessories ... ... 720 



Total weight ... ... ... 8,820 lbs. 



(2). 



Machine, light ... ... ... (],900 



400 gallons petrol ... ... ... 2,880 



30 gallons oil ... ... ... 270 



Crew, spares, etc. ... ... ... 950 



Total weight ... ... ... 11,000 lbs. 



