Rainbow Dash tried to reproduce the Sonic Rainboom many times without success. Several of these times were under the watchful eye of curious researchers. She eventually got fed up with them and started turning them away.

Over a year before the Longest Night, Dr. Haystacks decided to ask her himself. He knew it would be an uphill battle, so he would need a strategy.

Most students of Equestrian history will guess that the attempt was unsuccessful, but Dr. Haystacks would insist later that this attempt was part of the path that led to a successful reproduction some years later. And besides, it's not really failure if you've managed to find that something doesn't work.