Expert: Paul Soderman - 2/21/2005

Question
I was wondering what the lift coefficient of a scramjet would be. I'm thinking about the new X-43A plane or perhaps just a ball park figure. Also could you give me one for a passenger jet(Perhaps a Boeing 747)? Thank you so much. You have no idea how much help you could be providing! :-)

Answer
Mandeep

You haven't told me what flight condition you are considering.  In cruise, lift coefficient is as low as possible and still provide lift equal to weight in level flight.  Why not calculate it ?  

Lift = weight = Cl q S, where Cl is lift coefficent, q is dynamic pressure, and S is wing area.  I don't have the data for either plane, but you can find it in Jane's Aircraft book or elsewhere on the web.  Good luck.

Paul