Military Logistics using UAVs

India has a coastline of 7500 kilometres and shares a land border of 15200 kilometers with our neighbours which spans diverse and harsh environments, from the salt flats of Kachchh to high and cold Himalayan glaciers, and hot and dry Thar desert to dense and moist forests of Northeast. Maintaining vigilant border surveillance and monitoring requires setting up personnel in these extreme locations. To support our brave soldiers on these lines, a continuous and uninterrupted transport of supplies is of immense importance. Due to extreme locations, these supplies do not reach them easily. From camels in Thar Desert to mules in Kashmir, the last mile delivery is a great challenge. To move supplies even from one base to another situated in such terrains, for example, from one peak to another or across the mountain or swamp, great distances must be covered on ground, which also means longer time. This becomes extremely critical in times of emergencies such as natural disasters and border tensions when time is of great value. These hurdles can be covered in a lot less distance and time via air transport, which is where helicopters are used. However, it is not economical to use helicopters for small supplies. A Helicopter may be utilized for multiple such small deliveries, but this translates to longer waiting time for later deliveries.

These problems can be solved by using logistic UAVs respective to their target delivery location. In situations where a UAV is lost in service, a backup UAV can always be made airborne quickly. A UAV is an expendable resource, unlike a pilot’s life. In situations where the enemy keeps a deep sight near conflict zones with offensive intent on military movements, the use of large aircrafts such as helicopters and cargo planes becomes dangerous. In situations like these, UAVs, which are comparatively smaller in size, can maintain the supply chain by their reduced detectability on RADAR and satellite imagery. UAVs are slow moving targets so taking them down is relatively easy, if detected. However, shooting a UAV with a guided missile itself creates an asymmetry in warfare with UAVs costing way less than a manned aircraft and most of the times, less than a missile itself.

Although all types of geographies have their own logistics challenges, high altitude areas are most complicated when it comes to cargo transportation through UAVs. This is because of the terrain, low temperature, low air density and dynamic winds. In the hilly and mountainous regions, the wind sometimes blows across the ridgeline. This creates an updraft on the windward side and a downdraft on the leeward. When a UAV travels from updraft to downdraft region, it may become vulnerable to crash due to the terrain, resulting in high-cost equipment loss. The low temperatures in such areas affect the battery-operated UAVs adversely, reducing the usable battery energy and sometimes loss of power altogether. Moreover, the low density means that the UAV requires more power to lift. This can be overcome by increasing the size of propellers when it comes to multi-copters and increasing the wing area in fixed-wing UAVs. But doing so make such UAVs vulnerable to wind. This is because large propellers mean that the air is pushed at lower speeds, and large wings mean low forward velocity. A small wind disturbance can cause such UAVs to lose their lifting power very fast. Low air density also means less oxygen, which causes an airbreathing engine to suffocate and produce low power. The terrain also complicates maintaining communication link with the UAV. However, the use of intermediate relay UAVs and SATCOM is promising. Thus, it becomes very important to design a UAV considering all these factors.

Multi-copter UAVs do not require an established infrastructure to operate e.g. a runway, fixed-wing UAVs offer better efficiency yielding to long range, endurance and high speed, but are infrastructure dependant. Moreover, when it comes to resilience towards wind, fixed-wing UAVs are more capable than multi-copters. Another category is fixed-wing VTOL UAVs, these have vertical take-off and landing capability of multi-copters and efficiency of fixed-wing UAVs. It doesn’t mean that multi-copters and fixed-wing UAVs are useless, they have their own benefits. For example, multi-copters, mainly all electric, can be deployed faster and are practical for transporting lightweight cargo (5 to 10 kilograms) to very short distances (last mile logistics). Whereas fixed-wing UAVs can be used to transport larger cargo (middle mile logistics) with very less energy required, whether engine driven or battery operated. As mentioned earlier , the usable energy of batteries reduces in low temperature areas. Also, battery as a technology itself has very low energy content for the same weight (low energy density) in comparison to IC engines. In battery driven UAVs, the battery itself is significantly heavy, eating up the payload capacity, yet again yielding to less range and endurance.

For long range and heavy payload delivery in the last mile, fixed-wing VTOL hybrid UAVs are the most practical solution. The most common configuration being, VTOL powered through the battery and cruise supported by an IC engine. Such vehicles have the potential to transport cargo to hundreds of kilometres.  Apart from practicality and performance, such UAVs can be designed to have inbuilt failsafe features. For example, if the control surfaces fail, the VTOL rotors can assist in maintaining the attitude Similarly, if VTOL rotors or the batteries fail, the engine can still bring the UAV to a place where it can be landed conventionally. If the engine fails, the VTOL system can land it safely, or if the entire powerplant fails, there could still be a chance to glide to a place where it can be landed conventionally. These are just a few examples; the potential is immense. These UAVs are complicated to design and perfect; however, the science is there to engineer such systems. All it takes is to relentlessly work on bringing in RELIABILITY, RESILIENCE, SAFETY and SECURITY, and PERFORMANCE. 

The future of logistics in high altitude areas is the use of UAVs. They will ensure timely delivery of food, ammunition, medical and other supplies near and beyond the enemy lines. They will also be used to transport wounded soldiers. An autonomous swarm of such UAVs will be used to transport large cargo in a highly coordinated manner. Moreover, in future, to avoid detectability, narrower paths such as caves, tunnels and gorges will be navigated through, by autonomous UAVs. The UAVs will have fully autonomous advanced capabilities, with better obstacle detection and avoidance features that are unheard of.