RD-54 modification setups and instruction
RD-54 is by far the most iconic backpack of the Soviet-Afghan War. It was far from great, but it was one of the very few options available, so the choice for an "icon" was somewhat limited.
However, the RD-54 backpack was very inconvenient for Soviet-Afghan War (or any war for that matter). In it's original setup, it was not even a backpack, but more like a webbing system of the most complicated system ever. So, soldiers modified these backpacks to their taste - to improve the capabilities of the equipment.
The intent for the original RD-54
It is wrong to discuss a piece of equipment used in war, without looking at the doctrinal, by the book use. Most of the Cold War era equipment was developed for some particular task. More often or not, this task would never come up in reality but the equipment would still be used in some conflict.
RD-54 is a prime example of such equipment. It was designed after the Second World War, when Soviet generals were still under impression about the Allies Airborne operations. At this point, the doctrine of mass parachuting way behind the enemy lines had a lot of support in the Soviet chain of command.
The life of a single paratrooper was not considered as something valuable in this case. And hence the original RD-54 was just big enough to take supplies barely enough for one active firefight and 1-2 days of survival supplies. The size of the RD-54 also depended on the construction of the parachute and its aerodynamics, but since I am not an expert in the topic and you are probably not interested in that - I am not going to talk about this in detail.
The original setup of the RD-54
As was mentioned earlier, RD-54 is more of a webbing system than a backpack. The RD-54 in its original setup basically consists of three pouches, connected to each other. It is the main compartment, the 2-cell magazine pouch and 2-cell grenade pouch. RD-54 backpacks were also supplied with detached spade cover and sometimes with the first aid kit.
The original setup was supposed to be used with the main belt - the straps were not attached to the bottom of the main compartment of the backpack, so the belt was needed to hold the complete ensemble together.
While the pouches themselves do not present much of interest for the topic of this article, the main compartment does. In theory, it already had some features for light modernization - the holes and straps on each side of the main compartment. This allowed to attach various equipment on the outer part of the RD-54. Again, by the book it was designed for the greatcoat, which would hardly be practical in a airborne raid behind the enemy lines.
However, even the straps were designed in a weird way. The straps which are coming out of the bottom of the side compartments are attached in such way, that they have to go through the whole side compartment before getting outside. This is incredibly uncomfortable when packing the backpack with the equipment, as it essentially either lowers already low volume, or shortens the straps, making it hard to attach anything.
How RD-54 were modified in Afghanistan
As Soviet Union invaded the Afghanistan, things escalated rather quickly. Inability to use vehicles in many areas led to more and more dismounted operations. These tend to get longer in the mountains, and the helicopter resupply was complicated due to terrain and weather conditions.
At least some rucksacks were needed. Regular veshmeshok packs were completely out of fashion by this time and were pretty horrible to carry around, yet still were. RD-54 was a better option, though it was only available to paratroopers and needed some modification. Wearing it in its designed, webbing-like ensemble was completely impractical in a real war.
Here is a quick instruction on how to do it right:
First and foremost - remove the pouches
Soldiers would remove pouches themselves, as keeping them strapped to the backpack made little to no sense. They had little capacity and were uncomfortable to wear as intended by the book.
Second - complete the backpack straps on your RD-54
As was said earlier, the RD-54 was impossible to wear as a regular backpack without the use of the belt. After removing the pouches, the top straps were now available to connect to the bottom ones, creating the complete straps so that the RD-54 could be worn as a regular backpack.
Step three - add more straps to attach bulky equipment
Surviving a night in the mountains is no joke. You need to be prepared - equipment wise. You will need a jacket or at least a sweater and preferably a sleeping bag or at least a duvet for the night. Fitting this into tiny RD-54 compartment is not possible. So - it has to go on the outside. However, the straps provided were either too short or just completely gone because of use of the previous conscript. To attach bulky stuff you will need to add them manually.
Popular ways to modernize the RD-54 backpack
After these initial steps it is really up to you how to modify your RD-54 backpack. Well, try to stay within reason and look at the documental photos for the reference. Talking about the general trends, it was popular to attach some sort of self-made pouch for the water bottle or two, as they are incredibly discomfortable to be carried on the belt.
Adding additional pocket on the back of the main compartment was also common - a gas mask bag was usually used for it (though not the common civilian GP-5 bag). Pouches for magazines or grenades were usually attached to the main compartment, as the RD-54 pouches were used to make the chest-rigs, and the 3-4 cell pouches were made from very thick material.
Sometimes it was also practiced to sew two RD-54 packs together, or at least late the side pouched from one and attach in to the other. Though there are not many photographs showing this setup.