<!-- "none" is preferred when the title is sufficiently descriptive; see WP:SDNONE -->
This is a list of aviation-related events from 1904:
Events
- Frenchman Robert Esnault-Pelterie flies a glider based on the Wright brothers' glider designs but employing ailerons rather than wing-warping for control. His glider is the first full-sized aircraft to employ ailerons.
- During the Russo-Japanese War, the Imperial Japanese Army uses two Japanese-designed kite balloons during the Siege of Port Arthur (which begins on 1 August); they make 14 successful flights. It is Japans first combat use of military aviation of any kind.
- At Vladivostok, Imperial Russian Army engineer Captain Fyodor A. Postnikov and his crews make frequent ascents in spherical balloons and a kite balloon from Russian ships, and the armored cruiser Rossia tests various forms of air-sea communications from balloons and the use of shipboard balloons for directing gunfire against shore targets and in detecting naval mines.
January–December
- January – Before the beginning of the Russo-Japanese War, the Imperial Russian Navy conducts many experiments with towing balloons and man-lifting kites from its warships.
- 22 and 24 March – The Wright brothers apply for patents for their flying machine in France and Germany.
- 1 April – Captain Ferdinand Ferber makes a failed attempt to fly an Archdeacon glider at Berck sur Mer, Picardy.
- 3 April – Gabriel Voisin successfully flies a modified Archdeacon glider at Berck sur Mer, Picardy. Voisin added a canard to the design. His longest flight on this day is 25 seconds.
- 23 April – Thomas Scott Baldwin makes a flight with August Greth's dirigible The California Eagle at San Francisco. This flight predated his efforts with the California Arrow.
- April–May – John J. Montgomery and Thomas Scott Baldwin work together at Santa Clara College in California using a wind tunnel to refine propeller designs for dirigibles. These propeller designs were used on Baldwin's successful California Arrow later in 1904 and the wind tunnel was the first of its kind on the west coast of America.
- 9–11 May – The Imperial Russian Navy armored cruiser Rossia carries a balloon on a raiding cruise against Japanese ships into the Sea of Japan in the first use by a warship of a balloon on the high seas in wartime. The balloon makes 13 successful ascents before it breaks its mooring lines and is damaged after landing on the sea.
- 23 May – The Wright brothers make their first flight attempt in the Wright Flyer II. They are not successful.
- 25 May – In Tandil, Argentina, Guido Dinelli flies his "Aeroplano apparatus" glider attached to a bicycle for .
- 26 May – The Wright brothers make their first successful flight in the Wright Flyer II. It is the first of 105 flights they will make in the Flyer II during 1904.
- 3 August – Major Thomas Scott Baldwin demonstrates the first successful U.S. airship, California Arrow, at Oakland, California.
- 20 September – Wilbur Wright makes the world's first circuit flight, in the Wright Flyer II.
- 9 November – Wilbur Wright flies the Wright Flyer II a distance of near Dayton, Ohio, the first flight of longer than five minutes.