A better description of the planes would be of great help, and also if you could post some photos
of the planes. Description= high wing or low wing, make of engine and size if you can find it on the
side of the engine, how many control surfaces does it use to fly, (engine, elevator, rudder, ailerons),
tricycle landing gear or tail dragger. I am assuming by gas and your Dad's fuel description it is a
"glow fuel" (ethanol, nitro, castor mix) as today a "Gas" plane does actually use a gasoline / oil mix
similar to that used in your weed eater. A 9v battery connector tells me these are very old, if this is
the battery power for the receiver. However much more information is needed to give you some
kind of idea of exactly what you have bought.

Bill D.