Gravity Is a Harsh Mistress by Grundy

Euler: Involve Mathematics

Turukano frowned.

“Are you sure about this,” he asked his cousins dubiously, eying the nearly finished wings.

“Of course,” Ingo grinned. “And think how much fun it will be to rub it in to your older brother that you did something he didn’t.”

“You don’t have an older brother,” Turukano pointed out.

“I have four, and two of them are insufferable,” Curvo sniffed. “I’m sure. I did the math myself. It will work. But if you don’t want in…”

“I didn’t say that,” Turukano said hastily. “I just don’t want a lecture from your father about how elves can’t fly!”