Hydrodynamics Jokes

L. organized the seminar in hydrodynamics in his University. Among the regular attendees there were two men in the uniform, obviously military engineers. They never discussed the problems they were working on. But one day they ask L. to help with a math. problem. They explained that the solution of a certain equation oscillated and asked how they should change the coefficients to make it monotonic. L. looked on the equation and said: "Make the wings longer!"