15 people sounds like too many. I had enough trouble leading a group of 6-ish people that I eventually gave up on them/the project. Now I'm working on that same

15 people sounds like too many. I had enough trouble leading a group of 6-ish people that I eventually gave up on them/the project. Now I'm working on that same project (and a few others) with only one other person. It's much easier to deal with and our visions seem much more feasible. We're not immediately shooting for the biggest and bestest thing out there. Like VuongN said, I would bring it up next time you meet. People will see you as much more of a leader if you take the initiative to call out these three big talkers and can systematically go through their ideas and explain to the group why they're bad. If that doesn't work, it might sound harsh, but I would either find a new group entirely, or take a look at the 15 people in your group and at least cut it in half. Drop the people who contribute the least. It sounds like if you guys are still brainstorming ideas, it'll be easiest to do all this now, instead of waiting and potentially having to deal with NDA's and whatnot. Especially if the people who get cut are bitter.