As I searched it the naming is about the generation of parachutes ... for instance
JUMPS FROM HIGH SPEED AIRCRAFT, THERETURN TO AN OLD IDEA
In the middle of the 1950’s, there arrived a new transport aircraft for the airborne forces, the Tu-4D. It was a bomber outfitted as a transport. The Tu4D had advantages in comparison with older aircraft and allowed an air assault of personnel at higher speeds than before. At that time the airborne was equipped with the parachute
D-1, fully constructed to its own technical specifications and reliability. But the first mass jump from the Ty-4D showed several problems: the main canopy turned itself inside out and tore, suspension lines twisted to the very skirt of the canopy. There are recorded instances of the canopy malfunctioning and rolling into a lump wrapped with the suspension lines! Several parachutists received contusions to the head and face from the risers, others lost consciousness from opening shock….
D1-8:
In 1959, after all the modifications, the new parachute D-1-8 was introduced for outfitting paratroopers. In fact, it appeared to be a complete modernization of the parachute D-1. Experiments for the design had already been done for the stabilizing system of the PDPC-48. The new D-1-8 structurally repeated this method of operation although the design was significantly different.
D3:
In order to speed up and normalize the inflation of the stabilizing parachute, it was decided to sew special pockets (a “cap”) to the canopy of the stabilizing parachute in the form of a “stretching out” system. It turned out that these pockets reduced the rotation of the entire system during the decent.
D4:
In comparing the D-1-8 and D-3 parachutes with the D-4 appears one important change: the stabilizing parachute was taken to the outside of the container and placed inside a special pocket on the drogue bridle, and the sleeve of the main canopy wasn’t pulled out of the container during the time of stabilization. This meant that the container remained closed during the time of stabilizing, thereby guarding the main parachute from the chance premature opening in the wind stream during a jump from a high speed aircraft. Also, it eliminated pulling from the container a portion of the sleeve during the time of stabilization which had increased the problem of twisting and spinning.
D5:
The new parachute, created in 1969, was called the D-5. The engineer responsible for this parachute was Klavdia Petrovna Balakireva. In design the D-5 in place of a sleeve for the main canopy a d-bag was used, that during the time of stabilization was located in the closed container and was not used as part of the stabilizing system.
D6:
The idea of using a stabilizing device exploded (expanded wildly) and in a short time period there were many modifications of the parachute D-5. Using different canopies, but keeping the general structural parachute system (container- drogue) already worked out on the D-5 serial 2, new systems were designed for different purposes (for example, D-6, PCN-71,PV-3, CN-74, PTL-72, T-4C, Lesnik, PA, PCN-80, Lesnik-2, D-10). The container and drogue remained, practically, one and the same. Parachutes changed, new ones were developed, but the stabilizing system of the parachute D-5 series 2, having performed very well, has been used practically unchanged for already 40 years. The extensively used parachute systems D-6 and D10 have in their makeup the insignificantly changed stabilizing system, first used in 1970.
D8:
Supporting stabilizing parachutes were meant for the stabilization of a falling parachutist in the necessary position until the moment the pilot chute came into action. They were using this principle to make the first experiments in 1940. Experimental parachute systems were developed with several supporting parachutes of small size, for example the D-8 and the experimental variant TP-6 (Paraavis).
The concept appeared so: After exit from the aircraft, a staticline opened a flap on the container and put into operation four supporting parachutes, which by design were mounted on the risers and were intended to support the falling parachutist by the shoulders, more accurately by the risers, while the main parachute was still in the container. After the action of the AAD or the pulling of the ripcord main canopy deployment was accomplished by a pilot chute. An example of this system is the parachute D-8, which is shown in the photo.
