ACT 27 as freshmen is a good sign that he should be able to get 30+ in junior. He will need to work very high to bring it to 33+ for a decent chance at UMich or UIUC engineering from OOS. Purdue would be slightly easier. If you are relying on financial aid, you can pretty much cross out UIUC. Merit aids at UMich is very competitive. Purdue is again a little bit easier but you likely need ACT ~35 or higher for the presidential scholarship.
NC State has a great Aerospace Program but very hard to get into this year. They declined a lot of kids with great stats but worth a try if you want to come to NC 
Try and have him to take the current SAT at least once before they change it. There is a lot of material out there about the current one and sparse information about the new and improved test that they will be using next spring.