I've written a set of spaceship combat rules, Iron Fist, using the Aeronef mechanisms as a starting point which have been published in Ragnarok 57. If there is enough interest, Wessex Games will publish them. If you are not a member of the SFSFW you can purchase a PDF edition of Ragnarok 57 at Wargame Vault.
The problems faced by the American Republic regarding population are not unique and most of the major power blocs are looking for ways to increase the size of their armies despite limited population resource. Cloning has been regarded as the answer in Europe with both ONESS and EuroFed using clones to supplement their troop numbers, vital in a theatre were war of some scale is a day-to-day occurrence.
Initially clones were just standard human copies, albeit with an accelerated initial growth pattern, but more recently technology has allowed enhancements of the basic human model with variants grown that have increased stamina and enhanced abilities, beyond even the best special forces soldier. These super-soldiers are still quite rare but are becoming an increasingly used commodity on the 22nd century battlefield.
In the mid 22nd century the Solar System has been carved up between various power blocs who, by various means, both diplomatic and military, attempt to gain the upper hand.
Earth itself has been ravaged by the effects of nuclear war in Central Asia, the Middle East and Siberia, as well as by ecological disasters across much of the globe.
Colonies have been founded on a number of planets and moons of the Solar System and whilst colonisation is still in its early stages, it has not prevented man's greed following him from Earth and already battles and wars have polluted these new worlds...