The Gap Band Lawsuit: I Dropped a Bomb on My Brother

R&B legend "Uncle" Charlie Wilson is at war with his brother over just who exactly IS The Gap Band ... and who gets to keep making money off of the name.

Ronnie Wilson filed a lawsuit claiming Charlie is derailing his efforts to launch a comeback tour. In the docs, obtained by TMZ, Ronnie says he recently booked 2 big gigs -- one at B.B. King Blues Club & Grill in NYC, and another at Howard Theatere in Washington, D.C.

Ronnie says after he sealed the deals, Charlie -- who left the band in 2009 -- had his people step in and somehow interfere with the bookings. Ronnie says both venues pulled the plug.

The elder Wilson points out his band existed for years before kid bro Charlie joined in '72.

Ronnie says his new Gap Band stood to make more than $20k from the 2 gigs. He's suing for damages and to get the court to block Charlie from interfering with future bookings.

His point -- you might have been the lead singer, but this band is MINE, bro.