Other major G7e-versions that saw operational service during the war, were the first acoustic homing torpedo G7es(TIV) Falke and its improved successor G7es(TV) Zaunkönig.

The advantages of the G7e in contrast to the G7a wet-heater steam-driven torpedo rested in its simplicity and cheapness of manufacture (half the cost), as well as being virtually silent and leaving almost no visible trail of air bubbles to alert ships that they were under attack.

However, in all other respects, the TII was less reliable and performed unpredictably compared to the G7a(TI), with shorter range of 5,000 m (5,500 yd) and slower speed at 56 km/h (30 kn).

Additionally, the batteries of these torpedoes needed to be preheated to a temperature of 30 °C (86 °F) to operate with maximum speed and range, though generally this was not a problem since U-boats had the element of surprise and often had the advantage of firing the first shot.

Both the contact and magnetic detonators were unreliable, major flaws that also afflicted the United States Navy's standard Mark 14 anti-submarine and anti-ship torpedo.

However, the contact pistol of the TII also proved to be unreliable; the British battleship HMS Nelson managed to survive almost certain destruction when three torpedoes from U-56 struck on her keel, two broke upon hitting and the other failed to explode.

The sensitive sound-sensing equipment in Falke required the torpedo be as quiet as possible, hence it ran at only 37 km/h (20 kn); in addition, the firing U-boat was forced to stop its motors.

Only known to have been fired in action by three U-boats, U-221, U-603 and U-758, although regarded as successful, resulting in the sinking of several merchants, and its performance rated satisfactory, Falke was rapidly phased out of service.

It was replaced by the G7es(TV) "Zaunkönig" (referred to by the Allies as GNAT, for German Navy Acoustic Torpedo), which was faster and better able to home onto the sound of fast moving warships as well as merchant traffic.