The average salary for an Engineer in the United States Department of Defense (or DoD if you're in the know) is around $80k per year. When compared to the average salary for Engineering jobs in the private sector, a DoD Engineer should make at least $20k more per year.
That is the average, however. Entry level positions may start as low as $50k per year based on education and experience.
On the other side of the curve, Defense Engineers who have been with the government for more than a decade can expect as much as $130k per year. This, of course, could vary depending on the type of project an Engineer is on. After all, the best way to keep someone tightlipped about Top Top Secret projects is to make sure their pockets are lined.
You keep the cash. We'll take the pie crust.