Thrust distribution Inclined combustion chambers & AFTERBURNING

Inclined combustion chambers
22. In the previous example (Para. 14) the flow through the combustion chamber is axial, however, if the combustion chamber is inclined towards the axis of the engine, then the axial thrust will be less than for an axial flow chamber. This thrust can be obtained by multiplying the sum of the outlet thrust by the cosine of the angle (see fig. 20-2). The cosine =  Hypotenuse /Base and for a given angle  is obtained by consulting a table of cosines. It should be emphasized that if the inlet and outlet are at different angles to the engine axis, it is necessary to multiply the inlet and outlet thrusts separately by the cosine of their respective angles.
AFTERBURNING
23. When the engine is fitted with an afterburner (Part 16), the gases passing through the exhaust system are reheated to provide additional thrust. The effect of afterburning is to increase the volume of the exhaust gases, thus producing a higher exit velocity at the propelling nozzle.+

Fig. 20-2 A hypothetical combustion chamber showing values required for calculating thrust

24. Assuming that an afterburner jet pipe and propelling nozzle are fitted to the engine used in the previous

Thrust distribution Engine

Engine
19. It will be of interest to calculate the thrust of the engine by considering the engine as a whole, as the resultant thrust should be equal to the sum of the individual gas loads previously calculated.

Thrust distribution Propelling nozzle

Propelling nozzle

17. The conditions at the inlet to the propelling nozzle are the same as the conditions at the jet pipe outlet, i.e. 16,745 lb.  Therefore, given that the propelling nozzle-- It is emphasized that these are basic calculations and such factors as the effect of air offtakes have been ignored.

18. Based on the individual calculations, the sum of the forward or positive loads is 57,836 lb. and the sum of the rearward or negative loads is 46,678 lb. Thus, the resultant (gross or total) thrust is 11,158 lb.