About 100 of the early P-51A ( called NA 91 by North American ) were fitted with four 20mm cannon, many of these were sold to the RAF. In general it seems the 20mm guns were not as reliable as the 50 cal, and also the aircraft could only carry a limited supply of 20mm shells which were each about 3 times the weight of 50 cal.
Which aircraft? In WWII armament ranged from zero (trainers, etc) to rifle-calibre machine guns, heavy machine guns, cannons (15 mm upwards), heavy guns (57 mm, 75 mm, 105 mm), rockets, torpedoes, bombs, mines...
tank moves shoot machine guns and are more durable than cannons
It depends on what you classify as 'cannons' . Many aircraft were fitted with 20mm guns in exactly the same way as machine guns were. Some aircraft such as the Stuka, some other German aircraft and a few British aircraft were fitted with larger guns of 37- 40-mm calibre and these were often carried in pods under the wings and had very limited ammunition due to it's weight.
They mounted two 37mm automatic cannons.
to assualt the ground from an airplane with machine guns or cannons mounted on the airplane.
Nowadays? "A Machine" In previous times? "a weaponsmith", "a gunsmith".
You can get brownish clay, soilders that are red and blue, guns but no machine guns,cannons,and some grass.
Tanks use cannons; and aircraft use machine guns or automatic cannons (small caliber such as 20mm, 30mm, etc). Tank cannons are called "main guns." During the Vietnam War, the US Patton tanks fired 90mm main guns; while the Australian Centurion tanks fired 84mm guns.
.303 caliber machine guns mounted in the wings. Later models replaced those with 20mm Hispano-Suiza cannons.
They went from having only machine guns to much more advanced cannons and guided missiles.
Modern day pirates typically use rifles, machine guns, and RPGs.
There were several different types of machine guns in use. Most fell into the "medium" category, and had a bore typically ranging from 6.5 to 7.92mm. The heavy machine guns tended to have a bore in the vicinity of 12.7mm, but also includes the 14.5mm KPV machine gun. 20mm and larger are considered cannons.