The Dreadnought is an airplane from Nausicaä of the Valley of the Wind, a military transport aircraft of the Torumekian military, appearing in the film as the transports for the Torumekian army commanded by Kushana.
It possesses 10 decks, and is large enough to hold tanks or a fighter plane which exit through bay doors at the front of the plane, not to mention a large amount of soldiers. This airship landed using a set of ten non-retractable wheels. The Torumekian airship is covered with machine-gun nests and turrets, even on the wings for shooting down aircraft. However, even when flying in squadrons, these planes are very big and very slow, making easy targets for fighter pilots such as Asbel, who shoots down all five aircraft before being taken down by the Torumekian gunship.
This particular Torumekian aircraft seems like a much larger, jet-engine version of the Messerschmitt Me 323 "Gigant" military transport aircraft used by the Luftwaffe of Nazi Germany from 1942-1944. The Gigant, while much smaller and a propeller aircraft, was still the largest land based military transport of the war and could carry troops and small tanks. The tank would also exist through bay doors at the front. The Gigant was similarly riddled with machine gun nests and turrets including on the wings. It was also very slow, and a large target for fighter aircraft. The size of the Torumekian "Dreadnought" is more comparable with that of an An-225 Mriya or a C-5 Galaxy.