A few ideas for Dieselpunk units:
Multi-Charge Cannon
Requires: Dieselpunk, Aerodynamics, Ammunition
Stats: Siege Weapon, Strength 35, Movement 0 (maybe 1 if restricted to railroads), -100% Defense, Cannot Attack, Can Perform Ranged Attacks (Range 6), Causes Collateral damage (max 70% to 8 units), Accuracy 70, Can Bombard City defenses (-12% per turn)
Civilopedia: The origin of multi-chamber guns dates back to the 19th century. In 1857 U.S. arms expert Azel Storrs Lyman (1815–1885) was granted a patent on "Improvement in accelerating fire-arms" and built in 1860 a prototype which proved to be unsuccessful. The best such design was developed in Germany during WW2. The German V-3 cannon was built into a hillside and used multiple propellant charges placed along the barrel's length and timed to fire as soon as the projectile passed them, to provide an additional boost. This gave the weapon an unprecedented range, at the cost of being completely immobile. Unlike conventional rifled weapons of the day, the smoothbore gun fired a fin-stabilized shell, dependent upon aerodynamic rather than gyroscopic forces to prevent tumbling, which resulted in a lower drag coefficient, further increasing its range.
Notes:
http://en.wikipedia.org/wiki/V-3_cannon
Submersible aircraft carrier
Requires: Dieselpunk, Naval Aviation, Submarine Warfare, Steel AND (Oil Products OR Biofuels)
Stats: Submarine, Strength 60, Movement 7, +25% vs Wood Ships, -25% defense, carries 2 Airplanes, 25% Withdrawal chance
Civilopedia: Submarine aircraft carriers are submarines equipped with fixed wing aircraft for observation or attack missions. These submarines saw their most extensive use during World War II, although their operational significance remained rather small. The most famous of them were the Japanese I-400 class submarine and the French submarine Surcouf, although a few similar craft were built by other nations' navies as well.
Notes:
http://en.wikipedia.org/wiki/I-400_class_submarine
Submersible battleship
Requires: Dieselpunk, Mechanised Warfare, Submarine Warfare, Steel AND (Oil Products OR Biofuels)
Stats: Submarine, Strength 70, Movement 7, can bombard city defenses (-18% / Turn), causes collateral damage (max 60% to 1 unit), Targets carriers and transport ships first, Flank attack against carriers and transport ships, +25% vs Wood Ships, carries 1 Spy/Explorer/Great Person/..., 25% Withdrawal chance, upgrades into Attack Submarine
Civilopedia: Just before WW2 German navy planned to use huge submarines with several large deck guns, usually in two gun-towers (one fore and aft of the conning tower) as well as torpedo tubes. These boats were to have a crew of over 100 men almost double that of any constructed German U-boat. 4 contracts (U-112 thru U-115) were awarded to the AG Weser yard in Bremen on Jan 17, 1939 but wisely cancelled at the outbreak of war in September that year and none of the boats had been laid down at the time. These boats are often claimed to not only have been completed but sailed, usually on very clandestine missions.
Notes:
http://uboat.net/types/projects.htm,
http://www.combatsim.com/memb123/htm/feb99/photo/xib-illus.jpg,
http://forums.cgsociety.org/showthread.php?t=261379
