According to Estes catalog Launch Site Dimensions chart, a field 100' square is enough for A type motors and 400' altitude. They say a 200' square is okay for B type engine and 800'. I'd say that's too generous.
Carkeek is a disused line control model airplane field, a circle 200' diameter, with trees encroaching. In my humble opinion, 200' is about the right maximum altitude for Carkeek, and I don't think any of my rockets exceeded that altitude.
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Carkeek Park, 100' to the nearest tree, a lush Puget Sound view, and a ten minute drive. Do not bring a parachute; streamer or tumble/spin works best here.