Mistel (German for “mistletoe”), was the larger, unmanned component of a composite aircraft configuration (i.e. the actual flying bomb) developed and used by Luftwaffe during the later stages of World War II.
The composite comprised a small piloted control aircraft mounted above a large explosives-carrying drone and as a whole was referred to as the Huckepack (“Piggyback”), also known as the Beethoven-Gerät (“Beethoven Device”) and Vati und Sohn (“Daddy and Son”). However, in practice Mistel commonly refers to the whole composite configuration.
The piloted aircraft was a single-seat fighter (Bf-109 or FW-190); the unmanned drone actually used was Ju-88 medium bomber (other fighters and bombers were proposed but never deployed).
The bomber component (which was often a new aircraft rather than surplus) was fitted with a 1,800 kg warhead. The warhead was a cone-shaped charge fitted with a copper or aluminum liner that could penetrate up to seven meters of reinforced concrete.
Some 250 Mistels of various combinations were built during the war, but they were largely unsuccessful (dismal failure would be a better assessment). The biggest deficiency of Mistel was that (unlike successful Fritz X bomb or a Hs 293 missile that inspired the Mistel weapon) the former was an unguided weapon.
Consequently given formidable air defenses deployed by the Red Army and the Allied forces, it is no wonder that just about none of the Mistels hit their intended targets.
They were first flown in combat against the Allied invasion fleet during the Battle of Normandy in June of 1944, targeting the British-held harbor at Courseulles-sur-Mer.
While Mistel pilots claimed hits, none of these match Allied records; they may have been made against the hulk of the old French battleship Courbet, which had been included as a component of the Mulberry harbor at Arromanches and specially dressed up as a decoy by the Allies.
Serious blast and shrapnel damage from a near-miss was suffered by HMS Nith, a River-class frigate being used as a floating headquarters on June 24th. Nine men were killed and 26 wounded, and Nith was towed back to England for repairs.
As part of Operation Iron Hammer in late 1943 and early 1944, Mistels were selected to carry out key raids against Soviet weapons-manufacturing facilities—specifically, electricity-generating power stations around Moscow and Gorky.
Those plants were known to be poorly defended by the Soviets and irreplaceable. However, before the plan could be implemented, the Red Army had entered Germany, and it was decided to use the Mistels against their bridgehead at Küstrin instead.
On April 12th, 1945, Mistels attacked the bridges being built there, but the damage caused was negligible and delayed the Soviet forces for only a day or two. Subsequent Mistel attacks on other bridges being thrown across the Oder were similarly ineffective.
In other words, Luftwaffe would have probably been much better off using bombers as, well, piloted bombers. Or developing a radio-guided version of Mistel with a two-seat fighter (pilot and weapon operator) as the control/piggyback aircraft.