--- title: "How machine guns on World War I biplanes never hit the propeller" description: "Was it the gun that was designed to fire through the propeller, or the propeller designed to be used with the biplane machine gun?" date: "2024-08-13" modified: "2024-08-13" authors: - name: "Blake Stilwell" job_title: "Editor-In-Chief, Air Force Veteran" link: "https://www.wearethemighty.com/authors/blake/" url: "https://www.wearethemighty.com/popular/wwi-airplane-machine-guns/" categories: - "History" - "War History" - "World War I" tags: - "Air Force" - "Aircraft" - "Military History" - "Weapons" - "World War I" --- # How machine guns on World War I biplanes never hit the propeller ![biplane machine gun]() *(National Archives)* There was a lot of new technology brought to the battlefield during World War I. Two of those were used in tandem—and somehow managed to perfectly complement each other. It was the fighter plane and the machine gun, mounted perfectly for the pilot's use, without shooting up the propeller that kept the bird aloft. Was it the gun that was designed to fire through the propeller, or the propeller designed to be used with the [biplane machine gun]()? The answer is yes. **Also Read: [A New York artist painted each of the Red Baron's 80 aerial kills]()** The system worked because of synchronization gear which kept the gun from firing when the propeller would be hit by the bullet. While airborne, the prop would be spinning five times as fast as the weapon could fire, so there was little margin of error. The problem was solved by the addition of a gear-like disc on the propeller that would only allow the [gun to fire in between the blades' rotation](). Often called an "interrupter" the disc did not actually interrupt the firing of the weapon, it merely allowed it to fire semi-automatically instead of at an even pace. When the prop spun around to a certain position, it would allow the weapon's firing mechanism to fully cycle and fire a round. Usually, when the round was supposed to be interrupted, the weapon was actually just in the process of cycling. https://www.youtube.com/watch?v=VX3fDlR-SDw So pulling the trigger would essentially connect the weapon to the propeller, and the prop would actually be firing the gun. Letting the trigger go would disconnect the weapon from the propeller. Later versions, such as the Kauper interrupter used on the Sopwith Camel, allowed for multiple machine guns at different rates of fire. The interrupter was a welcome change from the early days of combat aviation, where props were sometimes metal plated *just in case* mechanically uncoordinated rounds hit the propeller, so the bullet would ricochet. ![biplane machine gun]() *Synchronization gear was also needed for later planes, such as the German Me-109 fighter, seen here in World War II.* ### Don’t Miss the Best of We Are The Mighty ****• [Snoopy was much more than just a World War I flying ace]()**** ****• [Ukraine is using a World War I ‘creeping barrage’ tactic to turn the tide of the war]()**** ****• [Your battle buddy was originally supposed to check your feet in the trenches of World War I]()**** ## Author Blake Stilwell is We Are The Mighty's Editor-in-Chief, covering military news, entertainment, and history, along with veteran education, employment and entrepreneurship. He is a former U.S. Air Force combat cameraman with degrees in Graphic Design, Television and Film, International Relations, Public Relations, Business Management and Middle Eastern Affairs. After leaving the military, he began working in film and television production in New York and Los Angeles, work that included ABC News, NBC Olympics, and HBO Sports. He then spent two years in Washington with White House Communications, before joining the Near East Foundation. At NEF he served as an International Development Fellow, then Communications Officer, and finally, Media Officer for the Middle East and Africa. Based in the Palestinian Territory, he coordinated strategic communications between eight country offices, international media, and government and NGO partners. He began a career focused on writing and editing in 2015 with We Are The Mighty. He left in 2019 for Military.com, but returned as Editor-in-Chief in 2025. Blake’s work has been seen on CBS News, Fox News, CBC, The Chicago Tribune, Task & Purpose, Military Times, Recoil, Skillset, American History, and was shockingly even used in a Supreme Court argument. He is an avid traveler and small business owner in Ohio, where he spends most of his energy fixing up a very old house. ### Author social links [Facebook]() [Twitter]() [Instagram]() [LinkedIn]()