[cadandcookies]

I'm going to assume you've looked into buses, hotel costs, and all of that and decided that you cannot feasibly afford to bring all the students you want to go without charging an exorbitant trip fee. If you haven't you should.

My team almost always brings all the members that "qualify" (are in good academic standing, showed up to meetings, contributed, etc) to our trips, but I can tell you how we choose our early team and sort priority after that.

The first sort we use is "can they actually go"-- can they afford the trip (financially and academically). If a student can't afford to go academically, they shouldn't be going. And if your team can't afford the bus to get the full team there, I'm assuming there are limited "scholarship funds" available.

Second sort is whether they are needed. Identify the drive team, pit crew, and presentation team-- the people that the team cannot compete without. This list probably isn't longer than ten people.It doesn't include seniors who are really good at machining but can't be on the pit or drive team.

After that, it's a lottery. Just make sure it's a fair selection process-- if you want to make sure you have some underclassmen there, say "we're going to take at least 5 freshmen, 5 sophomores, 5 juniors, 10 seniors" (numbers are adjustable-- that's just an example). Use a random line tool (like random.org) to select from among the subsets.

Overall, just make sure your selection process is clearly communicated to all involved and is fair and agreed upon ahead of time. Save yourself the trouble by getting the entire process right the first time.