A series of startup & taxis of de Havilland Canada DHC-2 Beavers, courtesy of Kenmore Air on Lake Union.
Lake Union, right in the heart of Seattle, is home to one of the busiest floating airdocks in the world, with daily flights up into the San Juan Islands, British Columbia, and even Alaska.
In one turn-around they may see four planes coming in-and-out every half hour. These planes take off heading north, and fly low over Gasworks Park. One day I'll post flyovers from that vantage point.
DHC-2s are piston driven and sound like giant motorcycles. They're pretty old planes, manufacturing having stopped decades ago. Nonetheless they are workhorses that just keep ticking when maintained.
Their larger siblings DHC-3s are turbine driven and sound like small jets when they start up. You can find some I recorded on the same day here: soundcloud.com/soundeziner/sets/dhc-3
Sound Devices 702
Picture by wikimedia user Dllu commons.wikimedia.org/wiki/User:Dllu under creativecommons.org/licenses/by-sa/4.0