Here's some additional info from Don Rinker (drinker@fast.net): This plane was formerly the property of Cole Palen at the Rhinebeck Aerodrome, It became part of the NASM collection after his death. This plane is actually a hybrid. Being some original, some made by Palen. The engine shown is an 80 LeRhone and should be a 130 Clerget. That was the engine Palen had, so they are using it.
Gustave Delage attempted to improve the design of the Nieuport 17 even further and went on to produce Nieuport 24 and 27, but these were not really competitive, largely because Allies were by then taking delivery of first outstanding Spads. US purchased about 400 of latter 2 types for use as trainers. Nieuport 28 ended up same way, as it was generally an uninspiring machine, Delage having completely broken away from previous design formula. 28 put into service during last few months of war and gained considerable degree of fame it did not really deserve. French Air Service rejected it as first-line equipment; however, because of availability and in absence of more suitable equipment, was supplied to 27th, 94th (Hat-in-Ring), 95th, and 147th squadrons of AEF's First Pursuit Group early 1918. Therefore first fighting plane to carry US colors into combat.