I made a math mistake in preceding post, and inadvertently submitted while checking calculations.

Correct dive height to attain 115.5 mph terminal velocity, neglecting air resistance would be about 445 feet, and probably about 600 feet with air resistance.

Correct dive height needed to attain 181.4 mph without air resistance would be about 1100 feet, and probably about 1500 feet with air resistance factored in.

Both appear do-able if the airplane hangs together and doesn't turn itself into a dangerous missile.