Tactical Transport NG …or in other words, send an aircraft to do a helicopter's job
Тактический транспорт NG (Next Generation) - самолет в роли вертолета
Эта статья была прописан во время соревнований "Объединенный грузовой самолет" в США. Идея состояла в том, чтобы найти более эффективное решение для пополнения запасов из воздуха в противоионы-карательных операций (Афганистан и Ирак). Причина, я публикую эту статью здесь предстоящих самолет Ил-112, который находится в той же категории, были кандидатами на участие в конкурсе "Совместный грузовой самолет". В статье описываются оперативные и материально-технические проблемы в борьбе с повстанцами операций и предлагает альтернативы настоящего решения с использованием вертолета в качестве основного средство для пополнения запасов с воздуха. Несколько графики и таблицы обеспечивают экономические и эксплуатационные сравнения (самолет) альтернатив против самого популярного транспортного вертолета в США и НАТО - СН-47 Chinook. Экономические данные получены из общедоступных данных из министерства обороны США.
Tactical Transport NG
…or in other words, send an aircraft to do a helicopter's job
Poor road infrastructure and long lines of communication made truck convoys extremely dangerous mean of resupply in Iraq and Afghanistan. In the beginning helicopters seemed like a good alternative, but high operational tempo and harsh conditions soon brought their resources to alarmingly low levels. Without enough helicopters for basic tactical missions, commanders couldn’t do anything else but send an aircraft to do a helicopters job.
Poor road infrastructure and long lines of communication in Iraq and Afghanistan
With the end of the Cold War, the armies of the developed world started with transformation for the new world order. Doctrines were changed. Rigid divisions were abandoned in favor of modular battlefield adaptable formations and increase in mobility became a major development trend. Today, twenty years later, an US Army’s Stryker brigade can deploy and start with combat operations anywhere on the globe five days after the first aircraft leaves the ground. However, that kind of mobility didn’t come for free. It was paid with increased dependency on logistical support. When deploying to area of operations, a Stryker brigade carries supplies for three days only. After that, depending on combat intensity and climate conditions, it needs to be resupplied every three to seven days.
One day’s supply
By definition “one day’s supply” is a unit or quantity of supplies adopted as a standard of measurement for estimating the average daily expenditure of a unit operating under stated conditions. For Stryker brigade with 300 armored vehicles, 500 trucks and 3900 soldiers operating in moderate combat (50% of forces engaged at any time) and temperate climate conditions (not too cold and not too warm), one day’s supply amounts to 65 metric tons of water, 16 tons of food, 79 tons of fuel, 12 tons of ammunition and 45 tons of clothing, spare parts, medical supplies and fortification material. Without fuel and water (that’s not in bottles) it is 220 NATO standard 463L palettes for one brigade. For one battlefield however, the numbers can be much higher. For example, in 2007 the number of US troops in Iraq reached the equivalent of 20 Stryker brigades.
Asymmetric battlefield
Today’s battlefields in Iraq and Afghanistan are not conventional battlefields. They are asymmetric battlefields without clear distinction between the rear and the front lines. For resupply convoys it means they are exposed to ambushes from the moment they leave their base.
During 2003 - 2007 there were more than 2800 casualties in resupply convoys
To make matters worse, the road infrastructure in Iraq and Afghanistan is poor (only 30% of the roads in Afghanistan are paved) and lines of communication are long (because counterinsurgency operations ask for a high dispersion of forces), forcing them to spend even more time out of their base. Statistics of the US Army's Center for lessons learned for a period 2003 - 2007 show that there were more than 2800 casualties in resupply convoys alone.
Aerial resupply
With such a high losses in resupply convoys commanders in Iraq and Afghanistan were compelled to transfer one part of resupply missions on to helicopters. In the beginning, it seemed like a good solution. Not only the casualties in resupply convoys decreased, but supplies started arriving where they were going to. However, high operational tempo and harsh conditions (sand and high ambient temperatures) soon brought their resources to alarmingly low levels. Without enough helicopters for basic tactical missions, the commanders couldn’t do anything else but send an aircraft to do a helicopters job.
Sand and high ambient temperatures decrease maintenance intervals for helicopters by three fold
Aircraft in the role of a helicopter
Due to its ability to land and take off vertically the helicopter is indispensible in modern warfare. However, when an adequate runway is available, an aircraft becomes several times more efficient mean of resupply. Confirming the statement above is the fact that the US Army, a generic user of helicopters since the Vietnam War, is still using a small fleet of C-23B Sherpa cargo planes. In spite of its modest payload of 3.3 metric tons or 30 passengers, the C-23B proved very useful in Iraq because of its ability to land on short improvised runways.
Bus or a plane? Despite modest payload the C-23 proved very useful in a role of a helicopter
One US Air National Guard unit operating there with 10 aircraft every month on average delivers 3600 passengers and 225 tons of cargo. However, the C-23B was originally acquired for European theater of operations, so in Iraq where temperatures in summer regularly exceed 40°C, its performance becomes marginal, to say at least. In Afghanistan, where aerodrome elevations are also high (Kabul International is at 6000 ft above sea level) the C-23B is not used at all.
Standard Hercules
After half a century of service in 60 air forces around the world, the C-130 Hercules became a standard in tactical transport aviation. Thanks to its optimally sized cargo cabin (to which almost all of today’s military vehicles and equipment are designed) and four engines, the C-130 offers operational flexibility the users of two engine aircraft can only dream of. For example, with one engine inoperative, the C-130 will still have 75% of power left while the two engine aircraft will only have 50%. In the mountains of Hindukush in the north of Afghanistan, such a difference can easily become a difference between life and death.
Hercules is a standard by itself in NATO logistics system
Within NATO, the C-130 is used by 15 air forces with six of them using the C-130J Super Hercules, latest variant equipped with 30% efficient engines and new digital avionics. Except in standard cargo variant, the C-130J Super Hercules comes in several specialized variants like the EC-130J (for electronic warfare), the MC/HC-130J (for Special Forces insertion and extraction) and the KC-130J (an aerial tanker), making it a truly comprehensive solution. However, the C-130J doesn’t come cheap, so only a few countries in the world can afford it in sufficient numbers.
C-130J Super Hercules costs US government roughly twice as much to own and operate than the smaller C-27J Spartan
Smaller plane vs. the C-130J
According to US Government accountability office reports and US Ministry of Defense reimbursement rates for FY 2011 one “long” C-130J Super Hercules costs US government roughly twice as much to own and operate than the smaller C-27J Spartan (purchase price 107 vs. 47 million and operating cost 5080 vs. 2111 dollars per flight hour). However, the C-130J carries twice as much cargo so it could be said that when flying fully loaded the C-130J costs roughly the same as C-27J. But, how often will that be the case?
C-27J Spartan
Afghanistan resupply mission - the analysis
When operations in Afghanistan peaked in summer of 2009, the USAF C-130’s transported 1700 tons of cargo in just a few months period. However, the mission sample analysis made afterwards showed that average pallet height and weight were 40% below what the C-130 was designed for and that the smaller and thus cheaper planes like the C-27J or C-295M could be an adequate substitute in more than half of those missions. The survey of potential landing sites also showed that the smaller plane would allow access to 10 additional Forward Operating Bases (FOB) in Afghanistan and as much as 30 in Iraq. Besides, the two smaller planes costing the same as one bigger can be on two different places at the same time. One bigger cannot!
Smaller aircraft vs. helicopter
As already mentioned, a helicopter is indispensible in modern warfare due to its ability to land and take off vertically. However, because of the way it accomplishes that, i.e. the way it generates lift, a helicopter will never have the range and speed of an aircraft. Furthermore, for the same reason, a helicopter is also a technically more complex machine, so its maintenance intervals will always be shorter and operating cost higher than the aircraft’s of the same size. For example, the maintenance interval for the CH-47D helicopter is every 200 flight hours while for the C-27J it is every 750 hours. The operating cost for the CH-47D is 11037 dollars per flight hour while for the C-27J it is 2111 dollars per flight hour (US MoD Reimbursement rates). Additionally, the CH-47D also cruises at a speed twice slower than the C-27J making the cost differential even bigger if the whole mission is taken into consideration.
C-27J (foreground) and CH-47 Chinook (background)
In the following example, the Forward operating base (FOB) resupply mission at a range of 450 nm is shown with the CH-47D and C-27J. The FOB has 3000 ft long improvised runway with soil strength of CBR 4 (equivalent to moist clay). Cargo is 6 tons on three NATO standard 463L palettes.
As can be seen in the example above, due to the slower cruising speed the CH-47D will spend twice as much time in the air than the C-27J. Multiplied with five times higher operating costs makes its total mission cost ten times higher. Furthermore, because of its relatively short range (325 nm with 6 tons of cargo carried internally), the CH-47D has to land twice during the mission so the total mission cost is even higher if cost of Forward Arming and Refueling Positions (FARP) is taken into account. The mission risk for the CH-47D is also higher, not only because every landing is a critical phase of the flight by itself (especially on desert terrain where brown-out phenomena occurs regularly), but because the slow flying helicopter approaching to land on an asymmetric battlefield is an easy target. In 2011 in Eastern Afghanistan one CH-47 approaching the land was downed with an unguided RPG rocket killing all 38 on board (including 19 US NAVY SEALs).
Smaller aircraft vs. smaller aircraft
With the C-130 being too big and the CH-47D too expensive (i.e. needed elsewhere) a smaller cargo plane looks like a very attractive alternative for resupply missions. Today, there are several such aircraft available on the market, but the two most popular are without a doubt the Airbus Military C-295M and the Alenia C-27J Spartan. Both are operationally proven aircraft and both have solid user base but there are differences between them.
C-27J vs. C-295M
The main difference between the C-27J and C-295M comes from the fact that one of them was uncompromisingly designed for military role, while the other was designed with a commercial role in mind as well.
Namely, for the reasons of competitiveness in the commercial market, which foremost values low purchase price and low operating cost, the C-295M has somewhat less robust airframe and “thinner” system architecture, making it cheaper but also less resistant to combat damage. When speaking of combat damage, it should be said that both aircraft are equipped with modular armor kits and modern self defense systems (with RWR, LWR, MAWS and chaff and flare launchers), but only the C-27J comes equipped with On Board Inert Gas Generation System (OBIGGS) which prevents explosion of a fuel tank in case it gets hit.
Thanks to its more powerful engines, the C-27J is also a better choice for operations in hot & high conditions like Afghanistan. However, where its engines really come to fore is not in climb but in descent - the tactical descent.
Tactical descent
Because of the danger of modern Man Portable Air Defense Systems (MANPADS) like the American Stinger or Russian Igla family of missiles (SA-16/18/24), tactical descent became a common flight phase on today’s battlefield. One method to execute a tactical descent is to overfly the aerodrome on a safe altitude (outside of the range envelope of MANPADS - usually 15 000 ft above runway elevation) and then descend in a spiraling trajectory within the aerodrome safe zone (zone regularly patrolled by friendly forces). However, a spiraling trajectory doesn’t allow for high speed because the turn radius would then increase and the aircraft would leave the aerodrome safe zone making it a less preferred option when the goal is to deliver as much cargo as possible in a short time frame.
Other method to execute a tactical descent is a high speed dive. In comparison to previously described spiraling descent, a high speed dive will not benefit from an aerodrome safe zone because it will have to start much further away but, since it takes approximately twice less time to land using this method the enemy will have much less time to react. However, for this method the aircraft must have huge airbrakes or some other kind of drag producing devices or its payload will become unacceptably low.
When speaking of airbrakes, it must be said that neither the C-27J nor C-295M have one, but what the C-27J has is a unique Full Authority Digital Engine Control (FADEC) system mode of operation which allows its propellers to be transformed into a huge airbrakes. How efficient that system is the author was shown in a full mission simulator during a visit to the C-27J assembly line in Turin, Italy. With 6 tons of cargo and fuel reserves for one hour alternate a descent rate of 4000 ft/min with at a nose down attitude of 20° was achieved. Starting from a distance of 15 nm and a height of 15 000 ft above aerodrome elevation a full stop landing was achieved in less than 4 minutes.
What’s also worth of mention here is how the Head Up Display (HUD) made things much easier. Using the Flight Path Vector or “the birdie” a pilot was always able to see where the touchdown point will be relative to the runway threshold. If for example, due to unforeseen wind on lower altitudes the touchdown point moves too much into the runway a pilot would simply deviate a few degrees from initial track allowing him to trade distance for excess altitude.
In aircraft without the HUD and the C-295M is one of them, a judgment of where the touchdown point is relative to the runway threshold is a matter of a pilot's experience so there is more chance that the tactical descent will end with the aircraft circling over the threshold to reduce excess speed or altitude (or both) at the same time being exposed to enemy fire.
Soft field performance
The biggest problem with unprepared runways is that they don’t last long. Depending on the aircraft’s structural efficiency (structural efficiency = payload/empty weight) and landing gear design, every improvised runway will last for only the limited number of passes (pass = landing + takeoff) before becoming unusable.
In the following example, the Forward operating base (FOB) resupply mission is shown with the C-27J, C-130J and C-295M but this time at a range of 900 nm. The FOB has the same 3000 ft long improvised runway with CBR 4 soil strength. The cargo for C-27J and C-295M is 6 tons on three and four palettes respectively. For the twice heavier C-130J the cargo is 12 tons on seven palettes since anything less would make it unacceptably inefficient.
As can be seen in the example above it is not the aircraft with the biggest payload (the C-130J) but the one with the highest structural efficiency (the C-295M) that will deliver more cargo on a soft unprepared runway. What can also be seen is the fact the C-27J and C-295M both need 30% less runway to land than the C-130J allowing them to resupply much more FOBs.
Cargo Cabin
In addition to everything mentioned above, the C-27J and C-295M are significantly different from the cargo cabin perspective as well. The cargo cabin of the C-295M is longer and lower than the C-27J’s, which is advantage if the palettes or troops transport will be the aircraft’s basic mission (the C-295M caries one palette and three soldiers more than the C-27J). However, if there is a need to carry very popular light tactical vehicles like the up-armored HMMWV (the Hummer) with hard top, than the C-295M’s cargo cabin is simply not high enough.
When it comes to loading and unloading of the cargo it must be said that the specially designed undercarriage of the C-27J makes things much easier because it can be elevated (up to half a meter) to match the height of the truck’s cargo floor or angled 4.3° tail down for vehicles to drive in. The C-27J’s cargo cabin floor strength is also twice that of the C-295M’s making the cargo handling inside the cabin much less of a planning task.
When landing is not an option
From logistician's point of view, the airland method (landing and offloading a cargo) is the preferable method of delivery, because during the airdrop a part of cargo and equipment always gets damaged or lost. The analysis of airdrops in Iraq and Afghanistan showed that only one third of airdrop equipment actually returns to base. Of that third, one third can be used right away, the other third must be repaired to be used again and the final third is so much damaged that it is not feasible to repair it. However, during the airdrop the aircraft is much less exposed to enemy fire (especially at night) and the off load of cargo is much faster allowing for more missions to be flown with the same number of aircraft.
TABLE 1: The C-27J and C-295M air drop performance
C-27J vs. C-295M - and the winner is…
As with many things in life, the answer is - it depends. If the smaller aircraft is being bought to relieve the bigger one like the C-130 Hercules or C-160 Transall, then the C-27J is a better choice because its cargo cabin makes it more compatible with the palette height of the bigger aircraft (repackaging of palettes for a lower cargo cabin is something to be avoided on the battlefield because it asks for additional infrastructure, security forces, manpower and time).
If the respective air force already owns the C-130J Super Hercules, that would be one reason more to consider the C-27J, because the two aircraft share the same power plant (the engines and props) and avionics - the two most expensive items from the maintenance perspective.
If a smaller aircraft is being bought to relieve a transport helicopter like the CH-47, than the C-295M is a better choice. Besides having almost identical cargo cabin cross section as the CH-47 (allowing for palette height standardization) the C-295M also has much better soft field performance, which makes it much closer to a helicopter than to a bigger cargo plane. The fact it was designed with commercial applications makes it much cheaper to operate too.
Repackaging of palettes for a lower cargo cabin is something to be avoided on the battlefield because it asks for additional infrastructure, security forces, manpower and time
However, if operations in hot & high conditions are where the aircraft will operate most of the time than somewhat lower engine power could be the limiting factor for the C-295M. In one engine out scenario even with emergency power rating on a working engine (increasing its power from 2645 to 2929 shp) the C-295M will still have 37% lower power to weight ratio than the C-27J.
If the smaller plane will be the only plane in respective the air force, then the selection should go in the direction of getting as much as much operational flexibility of the C-130 Hercules as possible. In that regard, the C-27J is again a better choice because it has more power (40%), more range (10%), more payload (20%), higher cargo cabin with stronger floor (100%) and more robust airframe (wing with three spars vs. two in C-295M, three generators vs. two, double vs. single hydraulic circuit). Even thou the mission analysis from Afghanistan showed that the C-27J could carry only 10% of outsize (non-palletized) cargo carried by the C-130, it is still twice more than the 5% that the C-295M could carry.
In addition to everything mentioned above, when choosing a cargo plane, the smaller air forces should also consider what is being used by their neighbors. The same aircraft would allow for bigger savings trough spares pooling and joint training. Additionally, the same cargo cabin would allow for more cargo standardization, making the joint efforts easier and thus more efficient.
On the other hand, everyday life is teaching us that diversity can be of great value. Where the C-27J falls behind, the C-295M excels and vice versa, allowing neighboring countries to complement each other with different aircraft. Anyhow, if the requirements are well recognized and priorities sorted out in the right order, one of these two aircraft should be more than enough to satisfy the needs of any operator.
Additional considerations
JPADS and “Low Cost - Low Altitude”
The main problem in airdrop is wind drift. As cargo descends slower or is being dropped from a higher altitude, the wind drift will be more pronounced and vice versa. For that reason, methods of airdrop are generally divided on high velocity (Low cost - Low altitude system) and low velocity methods (Joint Precision Air Drop System - the JPADS).
Low cost - Low altitude system
In high velocity methods the cargo plane functions more like a bomber. In its Flight Management System (FMS) database, ballistic properties of typical cargos are stored which are then processed together with the aircraft’s altitude, speed and wind’s direction and speed to provide the pilot (preferably on a HUD) with information like “firing solution”. What makes this method of airdrop ever more popular these days is the fact that development of Low Cost - Low Altitude system decreased the costs three fold in comparison to traditional systems. Like the word says, the Low Cost - Low Altitude system is using very cheap synthetic materials that are much cheaper than traditional parachute material. Today, the accuracy of this method is within couple of hundred of meters.
Joint Precision Air Drop System - the JPADS
In low velocity methods the JPADS system is becoming more and more popular system. It consists of airfoil parachute with strap-on GPS guidance unit. The system is very handy for resupplying the Special Forces units whose position shouldn’t be compromised. Dropped from an altitude of 25 000 feet, depending on aerofoil type and wind speed and direction, the JPADS system will travel 15 to 50 km with the accuracy of couple of tenths of meters.
Cargo plane as a Close Air Support (CAS) asset
With battlefield becoming more dynamic than ever before, the use of cargo plane as a CAS asset is getting more and more consideration. In such a scenario, the transport aircraft would be waiting on alert status on ground or in the air (since all of them are now equipped with aerial refueling system) to be called in to airdrop critical cargo, like ammo or medical supplies which are essential for the outcome of the battle. However, in such a scenario the cargo plane will not be the only asset providing the CAS (there will probably be UAVs, strike fighters, combat helicopters and MEDEVAC helicopters flying all over the place at the same time) so the data-link system will be needed. With data-link, not only that its crew will have the latest information about the ground and air situation over the battlefield, but the other CAS participants will also have the information about their position, time of arrival and intentions, making the whole operation much safer for everybody.
C-27J cockpit
Additionally, modern cargo planes are equipped with very sophisticated Electronic Warfare (EW) systems allowing them to significantly contribute in the making of accurate battlefield picture. Without the data-link, these systems are the exclusive property of the cargo plane. With data-link, these systems are the property of every coalition asset in the air or on the ground.
Эта статья была прописан во время соревнований "Объединенный грузовой самолет" в США. Идея состояла в том, чтобы найти более эффективное решение для пополнения запасов из воздуха в противоионы-карательных операций (Афганистан и Ирак). Причина, я публикую эту статью здесь предстоящих самолет Ил-112, который находится в той же категории, были кандидатами на участие в конкурсе "Совместный грузовой самолет". В статье описываются оперативные и материально-технические проблемы в борьбе с повстанцами операций и предлагает альтернативы настоящего решения с использованием вертолета в качестве основного средство для пополнения запасов с воздуха. Несколько графики и таблицы обеспечивают экономические и эксплуатационные сравнения (самолет) альтернатив против самого популярного транспортного вертолета в США и НАТО - СН-47 Chinook. Экономические данные получены из общедоступных данных из министерства обороны США.
Tactical Transport NG
…or in other words, send an aircraft to do a helicopter's job
Poor road infrastructure and long lines of communication made truck convoys extremely dangerous mean of resupply in Iraq and Afghanistan. In the beginning helicopters seemed like a good alternative, but high operational tempo and harsh conditions soon brought their resources to alarmingly low levels. Without enough helicopters for basic tactical missions, commanders couldn’t do anything else but send an aircraft to do a helicopters job.
Poor road infrastructure and long lines of communication in Iraq and Afghanistan
With the end of the Cold War, the armies of the developed world started with transformation for the new world order. Doctrines were changed. Rigid divisions were abandoned in favor of modular battlefield adaptable formations and increase in mobility became a major development trend. Today, twenty years later, an US Army’s Stryker brigade can deploy and start with combat operations anywhere on the globe five days after the first aircraft leaves the ground. However, that kind of mobility didn’t come for free. It was paid with increased dependency on logistical support. When deploying to area of operations, a Stryker brigade carries supplies for three days only. After that, depending on combat intensity and climate conditions, it needs to be resupplied every three to seven days.
One day’s supply
By definition “one day’s supply” is a unit or quantity of supplies adopted as a standard of measurement for estimating the average daily expenditure of a unit operating under stated conditions. For Stryker brigade with 300 armored vehicles, 500 trucks and 3900 soldiers operating in moderate combat (50% of forces engaged at any time) and temperate climate conditions (not too cold and not too warm), one day’s supply amounts to 65 metric tons of water, 16 tons of food, 79 tons of fuel, 12 tons of ammunition and 45 tons of clothing, spare parts, medical supplies and fortification material. Without fuel and water (that’s not in bottles) it is 220 NATO standard 463L palettes for one brigade. For one battlefield however, the numbers can be much higher. For example, in 2007 the number of US troops in Iraq reached the equivalent of 20 Stryker brigades.
Asymmetric battlefield
Today’s battlefields in Iraq and Afghanistan are not conventional battlefields. They are asymmetric battlefields without clear distinction between the rear and the front lines. For resupply convoys it means they are exposed to ambushes from the moment they leave their base.
During 2003 - 2007 there were more than 2800 casualties in resupply convoys
To make matters worse, the road infrastructure in Iraq and Afghanistan is poor (only 30% of the roads in Afghanistan are paved) and lines of communication are long (because counterinsurgency operations ask for a high dispersion of forces), forcing them to spend even more time out of their base. Statistics of the US Army's Center for lessons learned for a period 2003 - 2007 show that there were more than 2800 casualties in resupply convoys alone.
Aerial resupply
With such a high losses in resupply convoys commanders in Iraq and Afghanistan were compelled to transfer one part of resupply missions on to helicopters. In the beginning, it seemed like a good solution. Not only the casualties in resupply convoys decreased, but supplies started arriving where they were going to. However, high operational tempo and harsh conditions (sand and high ambient temperatures) soon brought their resources to alarmingly low levels. Without enough helicopters for basic tactical missions, the commanders couldn’t do anything else but send an aircraft to do a helicopters job.
Sand and high ambient temperatures decrease maintenance intervals for helicopters by three fold
Aircraft in the role of a helicopter
Due to its ability to land and take off vertically the helicopter is indispensible in modern warfare. However, when an adequate runway is available, an aircraft becomes several times more efficient mean of resupply. Confirming the statement above is the fact that the US Army, a generic user of helicopters since the Vietnam War, is still using a small fleet of C-23B Sherpa cargo planes. In spite of its modest payload of 3.3 metric tons or 30 passengers, the C-23B proved very useful in Iraq because of its ability to land on short improvised runways.
Bus or a plane? Despite modest payload the C-23 proved very useful in a role of a helicopter
One US Air National Guard unit operating there with 10 aircraft every month on average delivers 3600 passengers and 225 tons of cargo. However, the C-23B was originally acquired for European theater of operations, so in Iraq where temperatures in summer regularly exceed 40°C, its performance becomes marginal, to say at least. In Afghanistan, where aerodrome elevations are also high (Kabul International is at 6000 ft above sea level) the C-23B is not used at all.
Standard Hercules
After half a century of service in 60 air forces around the world, the C-130 Hercules became a standard in tactical transport aviation. Thanks to its optimally sized cargo cabin (to which almost all of today’s military vehicles and equipment are designed) and four engines, the C-130 offers operational flexibility the users of two engine aircraft can only dream of. For example, with one engine inoperative, the C-130 will still have 75% of power left while the two engine aircraft will only have 50%. In the mountains of Hindukush in the north of Afghanistan, such a difference can easily become a difference between life and death.
Hercules is a standard by itself in NATO logistics system
Within NATO, the C-130 is used by 15 air forces with six of them using the C-130J Super Hercules, latest variant equipped with 30% efficient engines and new digital avionics. Except in standard cargo variant, the C-130J Super Hercules comes in several specialized variants like the EC-130J (for electronic warfare), the MC/HC-130J (for Special Forces insertion and extraction) and the KC-130J (an aerial tanker), making it a truly comprehensive solution. However, the C-130J doesn’t come cheap, so only a few countries in the world can afford it in sufficient numbers.
C-130J Super Hercules costs US government roughly twice as much to own and operate than the smaller C-27J Spartan
Smaller plane vs. the C-130J
According to US Government accountability office reports and US Ministry of Defense reimbursement rates for FY 2011 one “long” C-130J Super Hercules costs US government roughly twice as much to own and operate than the smaller C-27J Spartan (purchase price 107 vs. 47 million and operating cost 5080 vs. 2111 dollars per flight hour). However, the C-130J carries twice as much cargo so it could be said that when flying fully loaded the C-130J costs roughly the same as C-27J. But, how often will that be the case?
C-27J Spartan
Afghanistan resupply mission - the analysis
When operations in Afghanistan peaked in summer of 2009, the USAF C-130’s transported 1700 tons of cargo in just a few months period. However, the mission sample analysis made afterwards showed that average pallet height and weight were 40% below what the C-130 was designed for and that the smaller and thus cheaper planes like the C-27J or C-295M could be an adequate substitute in more than half of those missions. The survey of potential landing sites also showed that the smaller plane would allow access to 10 additional Forward Operating Bases (FOB) in Afghanistan and as much as 30 in Iraq. Besides, the two smaller planes costing the same as one bigger can be on two different places at the same time. One bigger cannot!
Smaller aircraft vs. helicopter
As already mentioned, a helicopter is indispensible in modern warfare due to its ability to land and take off vertically. However, because of the way it accomplishes that, i.e. the way it generates lift, a helicopter will never have the range and speed of an aircraft. Furthermore, for the same reason, a helicopter is also a technically more complex machine, so its maintenance intervals will always be shorter and operating cost higher than the aircraft’s of the same size. For example, the maintenance interval for the CH-47D helicopter is every 200 flight hours while for the C-27J it is every 750 hours. The operating cost for the CH-47D is 11037 dollars per flight hour while for the C-27J it is 2111 dollars per flight hour (US MoD Reimbursement rates). Additionally, the CH-47D also cruises at a speed twice slower than the C-27J making the cost differential even bigger if the whole mission is taken into consideration.
C-27J (foreground) and CH-47 Chinook (background)
In the following example, the Forward operating base (FOB) resupply mission at a range of 450 nm is shown with the CH-47D and C-27J. The FOB has 3000 ft long improvised runway with soil strength of CBR 4 (equivalent to moist clay). Cargo is 6 tons on three NATO standard 463L palettes.
As can be seen in the example above, due to the slower cruising speed the CH-47D will spend twice as much time in the air than the C-27J. Multiplied with five times higher operating costs makes its total mission cost ten times higher. Furthermore, because of its relatively short range (325 nm with 6 tons of cargo carried internally), the CH-47D has to land twice during the mission so the total mission cost is even higher if cost of Forward Arming and Refueling Positions (FARP) is taken into account. The mission risk for the CH-47D is also higher, not only because every landing is a critical phase of the flight by itself (especially on desert terrain where brown-out phenomena occurs regularly), but because the slow flying helicopter approaching to land on an asymmetric battlefield is an easy target. In 2011 in Eastern Afghanistan one CH-47 approaching the land was downed with an unguided RPG rocket killing all 38 on board (including 19 US NAVY SEALs).
Smaller aircraft vs. smaller aircraft
With the C-130 being too big and the CH-47D too expensive (i.e. needed elsewhere) a smaller cargo plane looks like a very attractive alternative for resupply missions. Today, there are several such aircraft available on the market, but the two most popular are without a doubt the Airbus Military C-295M and the Alenia C-27J Spartan. Both are operationally proven aircraft and both have solid user base but there are differences between them.
C-27J vs. C-295M
The main difference between the C-27J and C-295M comes from the fact that one of them was uncompromisingly designed for military role, while the other was designed with a commercial role in mind as well.
Namely, for the reasons of competitiveness in the commercial market, which foremost values low purchase price and low operating cost, the C-295M has somewhat less robust airframe and “thinner” system architecture, making it cheaper but also less resistant to combat damage. When speaking of combat damage, it should be said that both aircraft are equipped with modular armor kits and modern self defense systems (with RWR, LWR, MAWS and chaff and flare launchers), but only the C-27J comes equipped with On Board Inert Gas Generation System (OBIGGS) which prevents explosion of a fuel tank in case it gets hit.
Thanks to its more powerful engines, the C-27J is also a better choice for operations in hot & high conditions like Afghanistan. However, where its engines really come to fore is not in climb but in descent - the tactical descent.
Tactical descent
Because of the danger of modern Man Portable Air Defense Systems (MANPADS) like the American Stinger or Russian Igla family of missiles (SA-16/18/24), tactical descent became a common flight phase on today’s battlefield. One method to execute a tactical descent is to overfly the aerodrome on a safe altitude (outside of the range envelope of MANPADS - usually 15 000 ft above runway elevation) and then descend in a spiraling trajectory within the aerodrome safe zone (zone regularly patrolled by friendly forces). However, a spiraling trajectory doesn’t allow for high speed because the turn radius would then increase and the aircraft would leave the aerodrome safe zone making it a less preferred option when the goal is to deliver as much cargo as possible in a short time frame.
Other method to execute a tactical descent is a high speed dive. In comparison to previously described spiraling descent, a high speed dive will not benefit from an aerodrome safe zone because it will have to start much further away but, since it takes approximately twice less time to land using this method the enemy will have much less time to react. However, for this method the aircraft must have huge airbrakes or some other kind of drag producing devices or its payload will become unacceptably low.
When speaking of airbrakes, it must be said that neither the C-27J nor C-295M have one, but what the C-27J has is a unique Full Authority Digital Engine Control (FADEC) system mode of operation which allows its propellers to be transformed into a huge airbrakes. How efficient that system is the author was shown in a full mission simulator during a visit to the C-27J assembly line in Turin, Italy. With 6 tons of cargo and fuel reserves for one hour alternate a descent rate of 4000 ft/min with at a nose down attitude of 20° was achieved. Starting from a distance of 15 nm and a height of 15 000 ft above aerodrome elevation a full stop landing was achieved in less than 4 minutes.
What’s also worth of mention here is how the Head Up Display (HUD) made things much easier. Using the Flight Path Vector or “the birdie” a pilot was always able to see where the touchdown point will be relative to the runway threshold. If for example, due to unforeseen wind on lower altitudes the touchdown point moves too much into the runway a pilot would simply deviate a few degrees from initial track allowing him to trade distance for excess altitude.
In aircraft without the HUD and the C-295M is one of them, a judgment of where the touchdown point is relative to the runway threshold is a matter of a pilot's experience so there is more chance that the tactical descent will end with the aircraft circling over the threshold to reduce excess speed or altitude (or both) at the same time being exposed to enemy fire.
Soft field performance
The biggest problem with unprepared runways is that they don’t last long. Depending on the aircraft’s structural efficiency (structural efficiency = payload/empty weight) and landing gear design, every improvised runway will last for only the limited number of passes (pass = landing + takeoff) before becoming unusable.
In the following example, the Forward operating base (FOB) resupply mission is shown with the C-27J, C-130J and C-295M but this time at a range of 900 nm. The FOB has the same 3000 ft long improvised runway with CBR 4 soil strength. The cargo for C-27J and C-295M is 6 tons on three and four palettes respectively. For the twice heavier C-130J the cargo is 12 tons on seven palettes since anything less would make it unacceptably inefficient.
As can be seen in the example above it is not the aircraft with the biggest payload (the C-130J) but the one with the highest structural efficiency (the C-295M) that will deliver more cargo on a soft unprepared runway. What can also be seen is the fact the C-27J and C-295M both need 30% less runway to land than the C-130J allowing them to resupply much more FOBs.
Cargo Cabin
In addition to everything mentioned above, the C-27J and C-295M are significantly different from the cargo cabin perspective as well. The cargo cabin of the C-295M is longer and lower than the C-27J’s, which is advantage if the palettes or troops transport will be the aircraft’s basic mission (the C-295M caries one palette and three soldiers more than the C-27J). However, if there is a need to carry very popular light tactical vehicles like the up-armored HMMWV (the Hummer) with hard top, than the C-295M’s cargo cabin is simply not high enough.
When it comes to loading and unloading of the cargo it must be said that the specially designed undercarriage of the C-27J makes things much easier because it can be elevated (up to half a meter) to match the height of the truck’s cargo floor or angled 4.3° tail down for vehicles to drive in. The C-27J’s cargo cabin floor strength is also twice that of the C-295M’s making the cargo handling inside the cabin much less of a planning task.
When landing is not an option
From logistician's point of view, the airland method (landing and offloading a cargo) is the preferable method of delivery, because during the airdrop a part of cargo and equipment always gets damaged or lost. The analysis of airdrops in Iraq and Afghanistan showed that only one third of airdrop equipment actually returns to base. Of that third, one third can be used right away, the other third must be repaired to be used again and the final third is so much damaged that it is not feasible to repair it. However, during the airdrop the aircraft is much less exposed to enemy fire (especially at night) and the off load of cargo is much faster allowing for more missions to be flown with the same number of aircraft.
TABLE 1: The C-27J and C-295M air drop performance
C-27J vs. C-295M - and the winner is…
As with many things in life, the answer is - it depends. If the smaller aircraft is being bought to relieve the bigger one like the C-130 Hercules or C-160 Transall, then the C-27J is a better choice because its cargo cabin makes it more compatible with the palette height of the bigger aircraft (repackaging of palettes for a lower cargo cabin is something to be avoided on the battlefield because it asks for additional infrastructure, security forces, manpower and time).
If the respective air force already owns the C-130J Super Hercules, that would be one reason more to consider the C-27J, because the two aircraft share the same power plant (the engines and props) and avionics - the two most expensive items from the maintenance perspective.
If a smaller aircraft is being bought to relieve a transport helicopter like the CH-47, than the C-295M is a better choice. Besides having almost identical cargo cabin cross section as the CH-47 (allowing for palette height standardization) the C-295M also has much better soft field performance, which makes it much closer to a helicopter than to a bigger cargo plane. The fact it was designed with commercial applications makes it much cheaper to operate too.
Repackaging of palettes for a lower cargo cabin is something to be avoided on the battlefield because it asks for additional infrastructure, security forces, manpower and time
However, if operations in hot & high conditions are where the aircraft will operate most of the time than somewhat lower engine power could be the limiting factor for the C-295M. In one engine out scenario even with emergency power rating on a working engine (increasing its power from 2645 to 2929 shp) the C-295M will still have 37% lower power to weight ratio than the C-27J.
If the smaller plane will be the only plane in respective the air force, then the selection should go in the direction of getting as much as much operational flexibility of the C-130 Hercules as possible. In that regard, the C-27J is again a better choice because it has more power (40%), more range (10%), more payload (20%), higher cargo cabin with stronger floor (100%) and more robust airframe (wing with three spars vs. two in C-295M, three generators vs. two, double vs. single hydraulic circuit). Even thou the mission analysis from Afghanistan showed that the C-27J could carry only 10% of outsize (non-palletized) cargo carried by the C-130, it is still twice more than the 5% that the C-295M could carry.
In addition to everything mentioned above, when choosing a cargo plane, the smaller air forces should also consider what is being used by their neighbors. The same aircraft would allow for bigger savings trough spares pooling and joint training. Additionally, the same cargo cabin would allow for more cargo standardization, making the joint efforts easier and thus more efficient.
On the other hand, everyday life is teaching us that diversity can be of great value. Where the C-27J falls behind, the C-295M excels and vice versa, allowing neighboring countries to complement each other with different aircraft. Anyhow, if the requirements are well recognized and priorities sorted out in the right order, one of these two aircraft should be more than enough to satisfy the needs of any operator.
Additional considerations
JPADS and “Low Cost - Low Altitude”
The main problem in airdrop is wind drift. As cargo descends slower or is being dropped from a higher altitude, the wind drift will be more pronounced and vice versa. For that reason, methods of airdrop are generally divided on high velocity (Low cost - Low altitude system) and low velocity methods (Joint Precision Air Drop System - the JPADS).
Low cost - Low altitude system
In high velocity methods the cargo plane functions more like a bomber. In its Flight Management System (FMS) database, ballistic properties of typical cargos are stored which are then processed together with the aircraft’s altitude, speed and wind’s direction and speed to provide the pilot (preferably on a HUD) with information like “firing solution”. What makes this method of airdrop ever more popular these days is the fact that development of Low Cost - Low Altitude system decreased the costs three fold in comparison to traditional systems. Like the word says, the Low Cost - Low Altitude system is using very cheap synthetic materials that are much cheaper than traditional parachute material. Today, the accuracy of this method is within couple of hundred of meters.
Joint Precision Air Drop System - the JPADS
In low velocity methods the JPADS system is becoming more and more popular system. It consists of airfoil parachute with strap-on GPS guidance unit. The system is very handy for resupplying the Special Forces units whose position shouldn’t be compromised. Dropped from an altitude of 25 000 feet, depending on aerofoil type and wind speed and direction, the JPADS system will travel 15 to 50 km with the accuracy of couple of tenths of meters.
Cargo plane as a Close Air Support (CAS) asset
With battlefield becoming more dynamic than ever before, the use of cargo plane as a CAS asset is getting more and more consideration. In such a scenario, the transport aircraft would be waiting on alert status on ground or in the air (since all of them are now equipped with aerial refueling system) to be called in to airdrop critical cargo, like ammo or medical supplies which are essential for the outcome of the battle. However, in such a scenario the cargo plane will not be the only asset providing the CAS (there will probably be UAVs, strike fighters, combat helicopters and MEDEVAC helicopters flying all over the place at the same time) so the data-link system will be needed. With data-link, not only that its crew will have the latest information about the ground and air situation over the battlefield, but the other CAS participants will also have the information about their position, time of arrival and intentions, making the whole operation much safer for everybody.
C-27J cockpit
Additionally, modern cargo planes are equipped with very sophisticated Electronic Warfare (EW) systems allowing them to significantly contribute in the making of accurate battlefield picture. Without the data-link, these systems are the exclusive property of the cargo plane. With data-link, these systems are the property of every coalition asset in the air or on the ground.