[vhcook]

I can't speak for all engineering mentors, but I like math. If a student either brought me some math showing they had done performance analysis on a design with favorable results or asked for my help doing the math, I would generally be more inclined to positively consider the idea. I also like CAD models, working prototypes, and analysis work that shows the student has considered both the positive points and the potential disadvantages and failure points.

If this were my team, I would directly ask the technical mentors what it would take for them to open up to a new idea. You may need to be fairly tactful, but I would definitely mention your fears that another rejection might crush the students.

Another thing to consider is that a lot of engineers get burned by a specific design feature at some point and tend to develop strong biases against designs that resemble them. I have had a lot of bad experiences with leaky, heavy, and ill-chosen pneumatics with long part lead times (on FRC robots) and with daisy-chained signaling architectures (in my day job). Designs with either of those features are generally a much harder sell when pitching an idea to me. Is it possible the design that was pitched hit somebody's pet peeve?