  We consider the hot spots in FR-II galaxies as sites of first order Fermi
acceleration of protons to the highest energies observed in cosmic rays. We
estimate the attainable maximum energy in the hot spot region allowed by the
canonical physical conditions, which are found from radio-to-optical
observations (Meisenheimer et al. 1989, A&A). We calculate observable the
proton flux and spectrum from this sources, using all knowledge about source
distibution (Peacock 1985, MNRAS) and particle transport in the microwave
background (Berezinsky and Grigor'eva 1988, A&A). We get excellent agreement
with the cosmic ray data points at ultra high energies. THIS PAPER GIVES THE
FUNDAMENTAL MODEL FOR THE EXPLANATION OF THE NEW AIR SHOWER DATA OF THE PROTON
COMPONENT OF THE COSMIC RAY SPECTRUM BETWEEN 0.1 AND 1 EeV (Gaisser et al.
1992, Phys. Rev. D in press, Stanev et al. 1992, A&A submitted), which is
subject of a subsequent paper (part II, Rachen and Biermann 1992, A&A
submitted).
