That is a help D120, thanks. I had already got there through the manipulation I mentioned above, which is how I got rid of the need for Laplace. I still ended up with a complex number in the mix though, which was most unwelcome.
Methinks that using Raymer I have found the solution:
Ground roll = (1/2*g*Ka)ln((Kt + KaVf^2)/(Kt + KaVi^2))
Where:
Kt = (T/W) - u
Ka = [rho/2(W/S)]*(uCL - CDo - KCL^2)
The formula I was using originally was from Raymer as well, but was looking for acceleration rather than the ground roll distance. I think this might be a case of 'keep it simple, stupid'
.
Thanks for the help - it's nice to have such a wealth of expertise to tap into.
Cheers,
Ginger
