Convair B-36, the flying aircraft carrier

The Convair B-36 (nicknamed Peacemaker) was the largest mass-produced piston engined aircraft ever made and the largest combat aircraft ever built. With a range of over 6,000 miles, some of these aircrafts needed special protection, so they were employed in "parasite" programs in which the B-36 carried smaller interceptors or reconnaissance aircraft.

The FICON (Fighter Conveyor) program was conducted by the United States Air Force in the 1950s to test the feasibility of a B-36 Peacemaker bomber carrying an F-84 parasite fighter in its bomb bay.

A production B-36 Peacemaker was modified with a special trapeze mechanism in its bomb bay, and a production F-84E Thunderjet was fitted with a retractable hook in the nose in front of the cockpit. The hook would link the fighter to the trapeze which would hold the aircraft in the bomb bay during flight, lower it for deployment, and raise it back in after the mission.

This tests were all soon abandoned, partly because air refueling appeared as a much safer solution to extend the range of fighters. The first parasite experiments with B-36 employed a XF-85 Goblin escort fighter, but (as you will see in this video) it proved to be a failure and a dangerous experience for pilots:

Airborne aircraft carriers

Using parasite fighters (an aircraft intended to be carried into a combat zone by a larger aircraft) is an old idea. The first parasite fighters were carried aboard military airships. Several plans were drawn up to outfit Zeppelin-type dirigible airships to launch and recover fighters. USS Akron and her sister ship USS Macon were regarded as potential "flying aircraft carriers", carrying parasite fighters for reconnaissance use.

During the 1930s, the Soviet Union developed a parasite aircraft project called Zveno . It consisted of a Tupolev TB-1 or a Tupolev TB-3 heavy bomber acting as a mothership for between two and five fighters. Depending on the Zveno variant, the fighters either launched with the mothership or docked in flight, and they could refuel from the bomber. It is estimated that Zveno-SPB flew at least 30 combat missions.

One of the more interesting experiments undertaken to extend the range of the early jets in order to give fighter protection to piston-engineed bombers, was the provision for in-flight attachment/detachment of fighter to bomber via wingtip connections. One of the several programs during these experiments was done with a B-29 mother ship and two F-84D "children", and was code named "Tip Tow."

On April 24, 1953, a F-84 flopped over onto the wing of a B-29 and both crashed with loss of all on board personnel. The project was cancelled.

More info and sources: 1, 2, 3, 4, 5, 6, 7