Dropping ordinance

How does an aircraft bombing system work?

An A-6E TRAM intruder armed with 500 pounders

The primary business end of the Intruder was of course the ordinance. The Intruder could carry almost every air weapon in the US Arsenal up to 1997 when it was retired and it wasn't called the airborne dump truck for nothing. The A-6 was a brute when it came to hauling bombs and going downtown to FED-EX people to hell. The A-6 armament system consisted of the electronics and electro-mechanics; the later end being the wing stations (pylons) and the "racks" or "rails" which held the weapons.

     When the first A-6-A Intruders arrived for service in 1965 in Vietnam with VA-75 and VA-85 it ran into a serious problem with both the racks it originally carried and the bombs that went to them. The bomb racks of 1965 were still of the Korean and World War II style which were built more for the slower prop driven planes like the A-1 Skyraider the A-6 replaced. The bombs were also old stocks and as our tightwad government usually does, it has a fire sale on old crap and unfortunately three A-6 crews paid the price. The older racks were strictly electro-mechanical free fall racks. That is... when you pressed the drop button on the control stick, the rack opened the securing grips on the bomb and allowed gravity to do the rest of the job. Well in the case of the intruder dropping multiple old World War II bombs....you got disaster. In one case, the bombs stayed in the aircraft slip stream which is the cone of air crafted as the A-6 goes into an attack dive. They tumbled into each other and exploded; shredding the poor Intruder and forcing the crew to bail out over North Vietnam.

     Two things were immediately apparent. The older bombs needed better fuse designs if they were going to stay in service, which by stupidity they did until they caused the near destruction of the USS Forrestal in a horrific 1967 fire. And the Intruder needed new bomb racks. The Douglas ordinance company quickly engineered new racks for single, triple and multiple bomb loads called SER, TER and MER racks.

The rack names stand for Single, Triple and Multiple ordinance carry and delivery ejection. You can't see from this computer image but the difference in the Douglas racks was the incorporation of a pyrotechnic activated plunger in all the racks. Each bomb station has a single 1 inch diameter power charge, a big shot gun shell, which drives a piston against the side of a bomb being released from the rack. This piston drives the bomb outside the plane's stream cone which prevents ordinance hang and the resulting loss of the aircraft. After the Douglas was rushed to Vietnam, no more Intruders were being blown up by their own weapons.

The Aero 7-A single release rack (The plunger is 11 and the shells are number 5)

      All Navy aircraft share the same program concept in delivering quantity as requirements demand. The number of bombs, the order which they are released, the time each bomb is released can be selected by the pilot. In the Intruder, release settings for bombs was programmed in nano-seconds or 1/100th of a second from 60 NS to 120NS. This was not only a safety feature with the aircraft but one which allowed precise laydown patterns for say runway destruction or bridge demolition. It was even effective if the Intruder had to lob or loft toss a stream of bombs over a ridge or land rise to catch enemy forces on the opposite side. In World War II the Germans excelled at being able to dodge the bombs of attacking prop planes by pre-estimating their ability to strike difficult positions. The A-6 took away that advantage.

   The bomb fuses were also modified in that where they used to arm the bomb right off the bat at release, the newer fuses allowed bombs to be armed clear of the aircraft and be capable of detonation before striking solid targets, such as when you need to destroy light infantry or light armor with fragmentation. Newer GPS designed bombs no loner need the traditional nose fuses as the pilot can now directly program each weapon to the specific requirements of his mission. There's more to dropping bombs than just point and shoot.