No calucations were required to figure out the timer setting. Once you had figured out the range, a book with tables in it was consulted and it told you the setting. The crew man that figured out the direction, range and corrections to the guns (the DC and the 37mm spotting round) was called “Computer”. This was the actual Army designation – not a nickname. We had NO actual computers. The gun elevation for the spotting round was different than the DC round. When the 37mm was on target the gun would be “superelevated” to the much higher elevation required by the DC round. The Computer would figure the superelevation by again using the charts in a book. I personally think the need to change the elevations caused the gun to be somewhat less accurate. But then, how accurate do you have to be when firing nuc’s?

Just some thoughts about the launching piston. It was attached to the projectile by two bayonet slots. When the gun was fired, part of the propellent gas would go through a strainer at the bottom of the piston and the pressure between the piston and projectile would separate them about 13 feet in front of the mouth of the gun. What’s interesting was that the piston would then begin to tumble and fall to the earth well before the target area. As there would normally be some of your own troops between the DC crew and the target, you could kill or injure your own troops! They would be warned over the radio when to take cover – not only as protection from the exploding nuc, but from the piston.

Yes, that was what the HOB switch was for. When the radar said it was the correct distance from the ground as set by the HOB switch, it would detonate. The switch had two settings. Each was set to one specific height. We always set it to “High” in practice because, in a war, special permission had to be granted to set it to “Low”. In the projectile in 1966, there was no provision to change the yield. The yield was set at the armory inside the projectile. We could not change it.

Can you clarify your last point: The timer only told the projectile when it could start to calculate it’s height in preparation for exploding. It was not just a “dumb” bomb.

Did it have some kind of altimeter inside of it? Is this what the “height of burst” switch manipulated? Can you provide any details as to how that worked in practice — e.g. was “high” set to a specific height and “low” another, or something else? I had assumed the “height of burst” switch was more related to yield considerations than a detection of actual height, but this was just an assumption.

There seems to be a fundemental misunderstanding of the timer. Even if you could set the timer working on the ground, the projectile would not explode. The timer was a safety device to prevent the bomb from going off too early. Please note that the timer was at the base of the rear antenna dome. It controlled when the information from the antenna domes would start to be used. So, the zero setting did have a purpose, was very important and was used in every firing event but it did not cause the explosion. The timer only told the projectile when it could start to calculate it’s height in preparation for exploding. It was not just a “dumb” bomb.

I served a Davy Crockett for 13 months in Korea in every crewman’s position. 1965-66.