Sitting at the large boardroom table was Robert Truxell, General Dynamics Vice President and General Manager of the Land Systems Division. Survivability for engineer Dr. Lett was more important than cost factors. Of primary importance is the ability of the tank to resist attack from heavy units that it would itself be attacking. Most of the rounds will be coming from the front therefore you have the greatest protection in the front.'' Using his blueprints he circled around the tank with a finger. As you look at the cardioid of protection around the M1A1, you see that it is fatter at the sides than any other tank.
Land mines are another critical threat.
We put two side walls and two intermediate walls into the design to give extra strength to the floor. Then we went over the torsion bars and covered them with armour plate so that if you have a mine exploding from underneath, the splintered torsion bars cannot penetrate the floor. The suspension is not based on a trailing arm but a forward arm. If a mine were to blow the track off it can be wrapped around that forward arm. Dr. Lett is retired from GD, but generously gave of his time to respond to TWR's questions.