Register to reply

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

Share this thread:
Oct31-12, 05:23 PM
P: 20
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?
Phys.Org News Partner Science news on
Experts defend operational earthquake forecasting, counter critiques
EU urged to convert TV frequencies to mobile broadband
Sierra Nevada freshwater runoff could drop 26 percent by 2100
Nov1-12, 07:44 PM
HW Helper
P: 5,365
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.

Register to reply

Related Discussions
Points of action for thrust and drag forces and lift-drag ratio Aerospace Engineering 1
Minimum thrust of engines at lift-off Introductory Physics Homework 2
Speed of Minimum Drag Advanced Physics Homework 0
Thrust,drag and lift on airplane Question Advanced Physics Homework 2
Calculate hydrostatic thrust Engineering, Comp Sci, & Technology Homework 2