Yep, through a search I've found 30 mph which converts to 45 fps, not found in the NAR or Tripoli safety codes (that I have on hand, anyway), but in a few cases like this one specified for high power flights at the Johnson Space Center:

Other requirements are that a rocket achieve at least 30 mph (45 fps) off the launch guide, and stability margins must be between .75 and 5.0 Calibers

Of course, the greatest factors in the safe departure velocity are crosswinds and stability factors which is why my two stage Majestic managed to go strait up in dead calm air.

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The other day I sat next to a woman who has a profound fear of flying. I wanted to comfort her, so I said, "Don't worry, we're not gonna' crash. Statistically, we got a better chance of being bitten by a shark." Then I showed her the scar on my elbow from a shark attack. I said, "I got this when my plane went down off of Florida." - Dennis Regan