X and his son Y are regarded as pioneers in the use of solid fuel rocket technology or missiles for military use. A military tactic they developed was the use of mass attacks with rocket brigades on infantry formations. It was only after Y's death that the technology eventually reached Europe.
The rocket men were trained to launch their rockets at an angle calculated from the diameter of the cylinder and the distance to the target. In addition, wheeled rocket launchers capable of launching five to ten rockets almost simultaneously were used in war. Rockets could be of various sizes, but usually consisted of a tube of soft hammered iron closed at one end and strapped to a shaft of bamboo. The iron tube acted as a combustion chamber and contained well packed black powder propellant. A rocket carrying about one pound of powder could travel almost 1,000 yards. In contrast, rockets in Europe, not being iron cased, could not take large chamber pressures and as a consequence, were not capable of reaching distances anywhere near as great.
Answer: X and Y are Hyder Ali and Tipu Sultan resp.
