GROUND PERFORMANCE 139 



Then turn to the front-view drawing of the machine and 

 mark the point A. Then with centre A and radius \d describe 

 a circle. 



Now find S", using this circle, in the same way as on page 

 IIO S' was found, using the propeller circle. 



-4, 



422W 



- S") + vo + 



- 



Then the length run on the deck in feet to get off is 



VI- 



1-151 W 



+ 



z/ w \ 



) lo ei 



where v 



and V, is the speed of the head wind in miles per hour relative 



to the deck. 



Getting Off the Ground. Using the same notation as above, 

 excepting that V w does not occur, the length of run to get off 

 the ground in still air in feet is 



Landing on a Deck. 



K = -ooi 4 95(Ri + R,) + 



R lt R 2 , k imam and S having their usual significances, while 

 L/D is the value corresponding to A, = I *o. 



V m is the slowest flying speed in miles per hour found on 

 page 126. 



Then the length run along the deck in feet on landing is 



Wr /V \ V - V n 



, / V M\ V W V W 



K[ 2 '33 logi, (y;) - ^^ 



where V w is the speed of the head wind in miles per hour relative 

 to the deck. 



Landing on the Ground. Let the effective coefficient of 

 friction between the machine and the ground be /JL, i.e. /JL is the 

 ratio of the ground resistance to the part of the weight of the 

 machine borne by the ground when the machine is on her wheels 

 and tail skid. 



V w is the alighting speed in miles per hour ; it is either the 

 slowest flying speed found on page 126, or the landing speed 



