Lockheed X-28

First Flights:  August 12, 1970 
Mission: 
Test bed Police seaplane
Major Accomplishments:
Well, it could get airborne and eventually land on water...

Power Source:
Continental 4 cylinder horizontally opposed engine (like BMW or Subaru)
Wing Span:
23'
Length:
17' 4"
Weight:
900 lb (fueled)
Maximum Speed:
135 mph
Maximum Altitude:
18,000'

Additional Information: Probably the most obscure X-Plane, the X-28 appears to have been hand built by one George Pereira. This was basically an experimental aircraft, but it did capture the US Navy's attention and was tested as part of the "Air Skimmer" program. 

The only X-28 is currently on display at the Kalamazoo Aviation History Museum in Kalamazoo, Mi.