A method for generating finite-dimensional approximations to the solut
ions of optimal control problems is introduced. By employing a descrip
tion of the dynamical system in terms of its attainable sets in favor
of using differential equations, the controls are completely eliminate
d from the system model. Besides reducing the dimensionality of the di
scretized problem compared to state-of-the-art collocation methods, th
is approach also alleviates the search for initial guesses from where
standard gradient search methods are able to converge. The mechanics o
f the new method are illustrated on a simple double integrator problem
. The performance of the new algorithm is demonstrated on a one-dimens
ional rocket ascent problem (Goddard Problem) in presence of a dynamic
pressure constraint.