Calculate the density at which the available thrust is equal to the minimum drag

In summary, to calculate the density at which the available thrust of a jet propelled aeroplane is equal to the minimum drag for the full fuel load case, use the formula Dmin = 2((CD,0*k)^0.5)*W = 5221N, where S = 29.5, W = 88000, CD,0 = 0.02, k = 0.044, and CT = 1.7*10^-4. However, without knowing the velocity, it is impossible to determine the density. More information is needed to relate velocity to drag and solve the problem.
  • #1
liam1992
20
0
Calculate the density at which the available thrust of a jet propelled aeroplane is equal to the minimum drag for the full fuel load case. Use the simplest assumption for the variation of engine thrust with density.

Wing area, S = 29.5
Weight, W = 88000
CD,0 = 0.02
k = 0.044
Max thrust (at sea level) = 16000N
CT = 1.7*10^-4

I use the formula Dmin = 2((CD,0*k)^0.5)*W = 5221N

The problem I have is that I can't work out the density without the velocity but there is no way to relate velocity to drag without density. Where do I go from here?
 
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  • #2
If you care to revise your posting, supplying the units and explaining what each of the three co-efficients is, I'll take a look at your problem.
 

1. What is the equation for calculating density?

The equation for density is density = mass/volume.

2. How is thrust determined?

Thrust is determined by measuring the force produced by the engine and the rate at which it is produced.

3. What is the minimum drag?

The minimum drag is the smallest amount of resistance an object experiences while moving through a fluid, such as air or water.

4. How is the density at which thrust equals minimum drag calculated?

The density at which thrust equals minimum drag can be calculated by setting the equations for thrust and drag equal to each other and solving for density.

5. Why is it important to calculate the density at which thrust equals minimum drag?

It is important to calculate this density because it allows for the optimization of the engine's performance. If the density is too high or too low, the engine may not be operating at its most efficient level.

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