The Flakpanzer I was a rare self propelled anti-aircraft gun conversion of the Panzer I in use by Nazi Germany during World War II. Its designation was Sd.Kfz.101 (Special Purpose Vehicle 101).
The Flakpanzer I was developed during the Battle of France when it was recognized that the motorised Flak was insufficiently armoured. The German Heereswaffenamt decided to combine light anti-aircraft guns with tank chassis. The chassis of the Panzer I was used for these conversions, simply because it was available. The conversions were done by the company Stoewer.
In total, 24 of these vehicles were built. During the conversion parts of the frontal superstructure and the complete cover of the engine compartment were removed to gain more even space to stand on. To achieve a better centre of gravity the frontal armour of the superstructure was moved about 18mm forward. The flaps on the side were made from simple sheet metal and did not offer real protection. When in action they were folded down and used to stand on. To gain more space (the Panzer I was a very small armoured vehicle) the radio was dismounted, communication was done with hand signals. The tanks were armed with the Flak 38, additionally the crew was armed with close-combat weaponry, like the K98 carbine. To make it easier for the driver to enter the vehicle, the main gun was mounted not centrally but slightly to the right. The ammunition was stored under the driver's seat and behind the loader. Due to insufficient space inside the vehicle, a coupling for the Sonderanhänger 51 trailer was added. Additional ammunition and replacement barrels for the gun were transported inside the trailer.