Small, quad engine aircraft on approach to KDCA?

Every so often I see an unmistakably small, quad engine aircraft on the approach path to KDCA from my vantage point by the Vienna Metro in the DC area. They appear to be BA 146 / Avro RJ or very similar in shape and size - however I never see any log of this on flightaware arrivals. The last sighting at roughly 7:30pm at 4/14/2015 (yesterday) prompted me to inquire here since there is no record otherwise (here or similar aviation websites). Anybody know more about this?

(or could I be mistaking a military craft going to AFB? These aircraft are going the exact same flight path as the many USair and JetBlue descents before and after)

very likely a C-17 headed for Andrews, or perhaps even Dover AFB … obviously at higher altitude than traffic on the approach to DCA

Probably not this one, although it Is smaller than a C-17.
B 24 Liberator Giant Scale RC Model Airplane Maiden Flight - YouTube)

These planes were not in dark military colors, from what I remember they were white with blue trim. Definitely not a C-17, that’s way too big. They appeared to be at the same altitude/path as other DCA approaches before and after.

If the owner blocked its n-number you wouldn’t see it but if you have an icom radio listen for the call sign or reg… Then check FAA registry to see what it is…