With the A34 (the General Staff specification), later named Comet, the tank designers opted to correct some of the Cromwell's flaws in armament, track design and suspension while building upon its strengths of low height, high speed and mobility.
This replaced the need for the Challenger and Firefly and acted upon the experiences gained through design and early deployment of the Cromwell.

Originally, it had been expected that the Cromwell would use the "High Velocity 75 mm" gun designed by Vickers but it would not fit into the turret.
 Development of the gun continued and as work commenced on the Comet, the gun design evolved into the 17 pdr HV (High Velocity).
The gun now used the same calibre (76.2 mm) projectile as the 17-pounder but the cartridge case was from the older QF 3 inch 20 cwt anti-aircraft gun loaded to higher pressures.
The resulting round was different from 17-pounder ammunition, being shorter, more compact and more easily stored and handled within the tank.

The 17 pdr HV was a shortened 17-pounder.
This made it possible to mount the gun on a smaller turret ring.
The gun was still capable against opponents and firing APDS rounds, more accurate and consistent than APDS from the 17-pounder and 6-pounder, which were inaccurate over 700m and often ricocheted.
The Challenger turret had been so large to allow space for two loaders.

Several other improvements were made and many Cromwell design revisions were incorporated, such as safety hatches for the driver and hull gunner.
The hull was fully welded as standard and armour was increased, ranging from 32 mm to 74 mm on the hull, while the turret was from 57 to 102 mm.

A new lower-profile welded turret was created using a cast gun mantlet for the 77 mm.
The turret was electrically traversed (a design feature taken from the Churchill tank), with a generator powered by the main engine rather than the hydraulic system of the Cromwell.
Ammunition for the 17 mm gun was stored in armoured bins.

The Comet's suspension was strengthened, and track return rollers were added.
As with later Cromwells, the Comet tank's top speed was limited from the Cromwell's 40+ mph to a slower, but respectable 32 mph (51 km/h).
This change preserved the lifespan of suspension and engine components and reduced track wear.

Similar to later Churchills, the Comet benefited from lessons learned in the co-operation of tanks with infantry.
It was fitted as standard with two radio sets: a Wireless Set No.
19, for communication with the regiment and the troop, and a No.
38 Wireless for communication with infantry units.
Like many British tanks, it also had a telephone handset mounted on the rear so that accompanying infantry could talk to the crew.
With the A34 (the General Staff specification), later named Comet, the tank designers opted to correct some of the Cromwell's flaws in armament, track design and suspension while building upon its strengths of low height, high speed and mobility. This replaced the need for the Challenger and Firefly and acted upon the experiences gained through design and early deployment of the Cromwell.
Originally, it had been expected that the Cromwell would use the "High Velocity 75 mm" gun designed by Vickers but it would not fit into the turret.  Development of the gun continued and as work commenced on the Comet, the gun design evolved into the 17 pdr HV (High Velocity). The gun now used the same calibre (76.2 mm) projectile as the 17-pounder but the cartridge case was from the older QF 3 inch 20 cwt anti-aircraft gun loaded to higher pressures. The resulting round was different from 17-pounder ammunition, being shorter, more compact and more easily stored and handled within the tank.
The 17 pdr HV was a shortened 17-pounder. This made it possible to mount the gun on a smaller turret ring. The gun was still capable against opponents and firing APDS rounds, more accurate and consistent than APDS from the 17-pounder and 6-pounder, which were inaccurate over 700m and often ricocheted. The Challenger turret had been so large to allow space for two loaders.
Several other improvements were made and many Cromwell design revisions were incorporated, such as safety hatches for the driver and hull gunner. The hull was fully welded as standard and armour was increased, ranging from 32 mm to 74 mm on the hull, while the turret was from 57 to 102 mm.
A new lower-profile welded turret was created using a cast gun mantlet for the 77 mm. The turret was electrically traversed (a design feature taken from the Churchill tank), with a generator powered by the main engine rather than the hydraulic system of the Cromwell. Ammunition for the 17 mm gun was stored in armoured bins.
The Comet's suspension was strengthened, and track return rollers were added. As with later Cromwells, the Comet tank's top speed was limited from the Cromwell's 40+ mph to a slower, but respectable 32 mph (51 km/h). This change preserved the lifespan of suspension and engine components and reduced track wear.
Similar to later Churchills, the Comet benefited from lessons learned in the co-operation of tanks with infantry. It was fitted as standard with two radio sets: a Wireless Set No. 19, for communication with the regiment and the troop, and a No. 38 Wireless for communication with infantry units. Like many British tanks, it also had a telephone handset mounted on the rear so that accompanying infantry could talk to the crew.
Comet (tank)