AH-1 Cobra Attack Helicopters for the Philippine Air Force

An AH-1 Cobra Helicopter of the Jordanian Air Force. Photo courtesy of the United States Air Force (USAF).

During his speech at the 120th Anniversary of the Philippine Navy last May 22, 2018, President Rodrigo Duterte said that he sent his National Security Adviser (NSA) Hermogenes Esperon Jr. to Jordan to facilitate the negotiations and the release of two AH-1 Cobra helicopters.1

Department of National Defense (DND) Secretary Delfin Lorenzana later added in an interview that two Philippine Air Force Pilots were sent to Jordan and they reported that the helicopters for transfer were in “good condition”.

The Pilots will also undergo training before the helicopters are brought over to the Philippines.2 No additional details about the transfer were released as of this writing, so for now I am just going to work with whatever information is available at the moment.

’The Cobra Helicopter’
First, just a short history about the AH-1 Cobra, it is the first ever purpose-built helicopter gunship to enter military service. Its first production version, the AH-1G, entered the United States (US) Army service in 1966, and saw combat during the Vietnam War the following year in 1967.3

Jordan bought twenty four (24) of the AH-1S Cobra helicopters in 1985, then received another nine (9) second hand, former US Army AH-1F units in 2000-2001, boosting their inventory to thirty three (33) aircraft.4

However, in 2010 Jordan transferred sixteen (16) of their Cobras to Pakistan, but then they replenished their stock when they received sixteen (16) refurbished Cobra helicopters from Israel in 2014 or 2015.5 Israel initially bought AH-1G and AH-1S helicopters, but most of these were reportedly later updated to the AH-1F version.6

The defense publication Jane’s though estimated that Jordan’s fleet of Cobra helicopters have gone down to twenty seven (27) units after some were lost to attrition. Of these, approximately three (3) were transferred to Kenya in 2017 while two (2) will now be transferred to the Philippines.7

’Oldie but Goodie’
The design of the Cobra helicopter will be more than 50 years old this year, and depending on which aircraft we get, they will either be second hand (if we get from the Cobras originally bought by Jordan) or even third hand (if we get them from the former US or Israeli Cobras) units. Also, the AH-1 Cobra is the “Mother of All Service Attack Helicopters” as it is the very first one to reach military service and go into full production.

However, despite the age of its design or whatever “hand” we will get, I think these aircraft could still offer good service to our Air Force because for one, we have never bought a true purpose built attack helicopter before. The helicopters we are using now for Ground Support are more like either light attack helicopters or armed versions of commercial helicopters.

Second, a number of countries are still using these aircraft up to now, including Jordan. In fact, Jordan just refurbished and modernized twelve (12) of their Cobra helicopters to use new Aviation Electronics (Avionics), Weapons, Countermeasures, etc.8

’Characteristics and Performance’
As of right now we don’t know what version we will be getting, or whether these will be refurbished and/or modernized. If so, we don’t know to what extent the refurbishing/modernizing will be. But for the purposes of this blog, I will assume that we will be getting the AH-1F because it is the last operational version used by the US Army and most countries have upgraded their Cobras to that standard.

I will be comparing the AH-1F to the two helicopters our Air Force is currently using for Ground Support, the MD-520MG and the AW-109E.9 10 11

WEIGHT – In terms of the Empty Weight, we can see that the AH-1F is much heavier than the MD-520MG or AW-109. It is almost four and a half times heavier than the MD-520MG and almost twice as heavy as the AW-109, and this is mainly because of its internal gun and other features which will be discussed later.

SPEED – The AH-1F has a higher Top Speed than the MD-520MG and AW-109, but a slower Cruising Speed than both aircraft. Then again, that stated Cruising Speed is with a full load of missiles, hence with lighter or less weapons we can expect that speed to improve.

DISC LOADING12 – Surprisingly, despite being a much heavier aircraft, the AH-1F has the same Disc Loading as the AW-109 thanks to its longer Main Rotor, indicating good maneuverability despite its weight, approximately as good as that of the AW-109.

INTFF/RANGE – In terms of the Internal Fuel Fraction (IFF)13 or Range, the AH-1F14 has approximately 18% more range than the MD-520MG, but a huge 67% less range than the AW-109 (this is assuming that the AW-109 uses its maximum five-cell Fuel Tank system).

PAYLOAD – This is one area where the AH-1F excels compared to the MD-520MG and AW-109 with 35% more payload than the MD-520MG and 26% more than the AW-109.

PASSENGERS – Both the MD-520MG and AW-109 are able to carry passengers allowing them to conduct Emergency Medical Evacuation in the field if necessary. The Cobra though only has space for the Pilot and the Gunner, hence it won’t be able to do any such emergency evacuations.

’Engine Comparisons’
The AH-1F only has one engine, same as the MD-520MG so on paper it has less margin of safety than the twin-engined AW-109. However, we have had good service with the MD-520MG over the decades, so hopefully we can extend that to the AH-1F also.

In terms of Engine Power though, this is one area where the Cobra really stands out, having five times more power than the MD-520MG and 37% more power than the combined power output of both engines of the AW-109.

The T53-L-70315 engine of the AH-1F has a stated Time Between Overhaul (TBO) that is 2,000 hours more than that of the 250-C20B16 engine of the MD-520MG, and surprisingly 1,000 more hours than the newer PW206C17 engines of the AW-109.

The T53 though only has mechanical controls like that of the 250-C20B, which is not as advanced as the Full Authority Digital Engine Control (FADEC) of the PW206C.

’Combat Survivability Features’
Because it is a true Attack Helicopter, the AH-1F has a number of features that help improve its survivability in combat, and among these are:18
– Self-Sealing Fuel Tank
– Armor Protection for the Engine, Fuel Systems, and Hydraulic systems
– Armored Seats with side panels that could be pulled up for more protection
– Armored Nose Plate to shield the Gunner
– Laser Warning Sensor

Additional survivability features of the Cobra helicopter are as follows:19
– The Main Rotor Blades are made of Composite material which has lower Radar and Acoustic (or sound) signatures than standard metal blades;
– The Composite Blades can also operate for 30 minutes even when hit with a 23 mm caliber cannon round;
– The Tailboom is strengthened so it can withstand a hit also from a 23 mm caliber cannon round;
– An Infra-Red (IR) Exhaust Suppressor which mixes cool air with the Exhaust Gas, lowering the temperature of the gas as it leaves the aircraft.

I’m not aware if any of these features being included in our MD-520MG and AW-109 Helicopters, but I think that at best, those two will only have some of these features, but not most.

The refurbished and modernized Cobras by Jordan have additional defensive equipment installed like a Missile Approach Warning Sensor (MAWS) system.20 These could also be fitted on our Helicopters if they go thru the same or similar improvements.

These built in protection won’t matter too much against our internal enemies, we have been operating the lightly protected MD-520MG for decades and none has ever been lost to enemy fire as far as I know. But these features will be important when we go up against better armed opponents, like the armies of other countries, for example.

’AN/ALQ-144’
A standard defensive feature on the AH-1F is the AN/ALQ-144 Infra-Red Counter Measure (IRCM) system which is mounted just behind the Main Rotors. It works by generating heat that is higher than any part of the helicopter, and then that heat is modulated by spinning optical elements to deceive or confuse enemy IR sensors.21

Although this system was first introduced in the 1970s, it still very much in service today in newer versions and is still in production by the BAE Systems company.22 Unfortunately, the AN/ALQ-144 does not seem to be present on the AH-1F units that were given to Kenya,23 hence might not be included with our aircraft also.

’Pylons and Misels’
One main advantage the AH-1F has over our other combat helicopters is its ability to handle a lot of weapons. Not only can it carry a heavier load of weapons than the MD-530MG and the AW-109 with a full tank of fuel, it also has more Pylons to distribute those weapons to with four Pylons per aircraft instead of just two.

The AH-1F also comes as already qualified for use with FIM-92 Stinger Anti-Air and BGM-71 Tube-launched, Optically tracked, Wire-guided (TOW) Anti-Tank Missiles24 while our MD-520MG and AW-109 have not been set up for use with any missiles yet, at least not that I know of.

The Stinger and TOW missiles are a bit old, though, but both are still in production.25 26 The TOW in particular has been experiencing a sort of renaissance lately since it was used a lot in the latest wars in the Middle East. There are a lot of new videos on Youtube the last couple of years showing the TOW taking out Tanks, other Armored Vehicles, Enemy Positions, etc. in Syria and Iraq.

If these Cobras arrive ahead of the AW-159 Wildcat Helicopters of the Philippine Navy, then they will be the first missile capable helicopters to enter service with the Armed Forces of the Philippines (AFP).

’Internal Gun’
But perhaps the AH-1F’s biggest advantage is its internal gun, the M-197 three-barreled Electric Gatling Gun. Neither the MD-520MG nor the AW-109 have an internal gun, they instead use guns mounted on pods which they then carry on their Pylons.

The M-197 uses the 20 x 102 mm Vulcan caliber ammunition, the same ammo used on the A-50 Gun System (GS) of our FA-50PH Fighting Eagle Lead In Fighter Trainer (LIFT) Aircraft. The 20 mm Vulcan round is quite powerful as it has more than three (3) times the Kinetic Energy (KE) at the muzzle (at 53.6 kJ versus just 16.9 kJ)27 than the .50 Browning Machine Gun (BMG) caliber rounds used by our MD-520MG and AW-109 helicopters.

The MD-520MG and AW-109 though typically carries two gun pods, whereas while the M-197 has three barrels, it only uses them one at a time and the whole system counts as just one gun. Of course the AH-1F can also carry gun pods also if necessary.

’Ammo, Turret and Firing Rate’28 29 30
The AH-1F also carries a lot more ammunition for its gun compared to our other helicopters. The Rocket and Machinegun Pod (RMP) used by our AW-109 helicopters and the Heavy Machinegun Pod 250 (HMP250) used by our MD-520MG helicopters has a magazine capacity of only 250 rounds of .50 caliber ammo. The AH-1F, on the other hand, has a magazine capacity of 750 rounds of the 20 mm Vulcan ammunition, or three (3) times more than either pod.

The AH-1F’s M-197 gun is mounted on a Nose Turret, which means you don’t have to aim the entire aircraft like on an MD-520MG or AW-109 to hit a target. The gun can swivel 110 degrees on either side and/or 20 degrees up or 50 degrees down on its own so it can rake a bigger area with gunfire on a single pass. It also allows the gun to be focused on a particular target longer if needed while the aircraft is moving.

The Cobra also has a Helmet Sight Subsystem (HSS) that allows the Pilot or Gunner to aim the M-197 just by moving their head and peering thru an Eyepiece with a Sight Reticle,31 allowing for quicker aiming of the weapon at closer ranges.

The use of an HSS was first popularized by the 1983 movie, Blue Thunder. Here is a good video in real life showing the Cobra’s HSS being demoéd:

‘Disadvantages’
On the downside, although in principle the M-197 is capable of firing up to 25 rounds per second or rps (or 1,500 rounds per minute or rpm), its practical firing rate is limited to only 12 rps (or 730 rpm) which is lower than the combined average rate of fire of 34 rps (or 2,050 rounds per minute) of two RMP or HMP250 pods which the MD-520MG or AW-109 usually carries.

With a much higher magazine capacity for ammunition that is more expensive, then the Ammunition Costs of the AH-1F will be much higher than the MD-520MG or AW-109. And then there are also reports of the M-197 jamming frequently,32 so our Air Force will need to take note of that.

’Sensors and Operating Costs’
A Night and Adverse Weather Sensor System is available for the Cobra, it’s called the Cobra Night Imaging Thermal Equipment (C-NITE) which is an earlier and less capable version of the Forward Looking Infra-Red (FLIR) system now being used on our AW-109 helicopters.

However, only a small number of US Army Cobra helicopters were reportedly equipped with the C-NITE,33 and I’m not sure if this system were fitted to the Jordanian Cobras. But a modern FLIR system similar to the ones used by our AW-109 can be installed just like what Jordan did when they modernized some of their AH-1 units.34

In terms of Operating Costs or Cost per Flight Hour (CPFH), the only available data I could find are from civilian examples, but I think this should still give us a good idea on the comparative CPFH of these various aircraft.

The AH-1 has an estimated operating Cost per Flight Hour (CPFH) of around USD 1,678 per hour when adjusted for inflation35 (taken from a 2007 figure36). This is 40% more than the estimated USD 1,042 CPFH of the AW-10937 and almost three (3) times the CPFH of the MD-520MG which is only USD 589 per hour.38

’Parting Shot’
Despite its age, it seems that these Cobra Helicopters still offer a significant upgrade in the capability of our Air Force. They can carry more and heavier weapons than our existing armed helicopters, they are missile ready and has better built in protection. They also have a more powerful gun that can be aimed better and they carry a lot more ammunition for that gun.

They won’t be able to do any emergency evacuations if needed, though, and the Air Force will have to spend more for the ammunition of these aircraft. They also has a higher estimated Operating Costs than our existing aircraft and their M-197 gun is reportedly susceptible to jamming, limiting the aircraft’s effectiveness in the field when that happens.

Nevertheless, these Cobras will still feature a number of “firsts” in service with our armed forces, including:
– First true Attack Helicopter;
– First aircraft to have a Gun on a Turret Mount;
– First missile capable helicopters (assuming they arrive ahead of the Wildcats);
– First aircraft with a Helmet Sight System

I hope that if they work out well in our service, and if so then we can get more of them in the future.

An AH-1 Cobra Helicopter of the Jordanian Air Force firing its cannon. Photo courtesy of the United States Air Force (USAF).

SOURCES:


  1. Duterte: Jordan Giving PH Two Attack Helicopters,
    (https://web.archive.org/web/20180522221217/http://news.abs-cbn.com/news/05/22/18/duterte-jordan-giving-ph-two-attack-helicopters
  2. Helicopters from Jordan to Boost Philippines Security Measure,
    (https://web.archive.org/web/20180525062011/https://www.msn.com/en-ph/news/national/helicopters-from-jordan-to-boost-philippines-security-measure/ar-AAxL0JC
  3. Huey Cobra Gunships by Chris Bishop, p. 6-8,
    (https://www.educacion-holistica.org/notepad/documentos/War/New%20Vanguard/Huey%20Cobra%20Gunships.pdf
  4. Huey Cobra Gunships …, p. 41 
  5. Kenya takes delivery of AH-1 Cobras,
    (https://web.archive.org/web/20180317232036/http://www.janes.com/article/71927/kenya-takes-delivery-of-ah-1-cobras
  6. Huey Cobra Gunships …, p. 40 
  7. Philippines to receive Cobra helos from Jordan,
    (https://web.archive.org/web/20180524135303/http://www.janes.com/article/80285/philippines-to-receive-cobra-helos-from-jordan
  8. Upgraded Cobra Takes a Bow [SOFEX18D2],
    (https://web.archive.org/web/20180509090214/http://www.janes.com/article/79924/upgraded-cobra-takes-a-bow-sofex18d2
  9. AW109 Power Equipment and Technical Data,
    (https://web.archive.org/web/20131024033510/http://www.agustawestland.com/product/aw109-power-1
  10. MD500 Series Technical Description,
    (https://web.archive.org/web/20131113222714/http://www.mdhelicopters.com/v2/pdfs/products/MD500_Series_TechDescription.pdf
  11. The Bell AH-1 HueyCobra, Section [6] Army TOWCobra: AH-1Q, AH-1S, AH-1P, AH-1E, AH-1F,
    (https://web.archive.org/web/20170913210508/http://www.faqs.org/docs/air/avcobra.html
  12. Disc Loading here is computed by dividing the Maximum Take Off Weight (MTOW) of the helicopter with the Area of its Rotor. 
  13. Internal Fuel Fraction is computed by dividing the Total Weight of the Internal Fuel of the aircraft by its MTOW. 
  14. The weight of the AH-1F’s Internal Fuel was calculated by multiplying its Fuel Tank Capacity of 936 Liters with the Standard Fuel Density for Aviation Fuel of 0.81 kg/L 
  15. This Day in Aviation – 26 December 2015,
    (https://web.archive.org/web/20180617064301/https://www.thisdayinaviation.com/tag/lycoming-t53-l-703/
  16. MD-500 – Peak Performer, Flying Magazine, June 1989, p. 50 
  17. New TBO Program for PW206 and PW207 Engines,
    (https://web.archive.org/web/20180126121319/http://www.marketwired.com/press-release/new-tbo-program-for-pw206-and-pw207-engines-1763414.htm
  18. Huey Cobra Gunships …, p. 7 
  19. US Army Aviation Digest – Oct. 1979, “Modernized Cobra Part II”, p. 28 and 43-45,
    (http://www.rucker.army.mil/avjournal/1970/1979/AVN_DIG_1979_10.pdf
  20. Upgraded Cobra Takes a Bow … 
  21. AH-64D Aircraft Survivability Equipment (ASE), p. D-74,
    (https://web.archive.org/web/20180617064505/http://gomotherrucker.com/mem/fdrgifhsnu4/ah64/studenthandouts/0926ASE.pdf
  22. AN/ALQ-144 Infrared Countermeasures Set,
    (https://web.archive.org/web/20171030163523/https://www.baesystems.com/en/product/analq144-infrared-countermeasures-set
  23. Kenyan Cobra AH-1 Being Tested,
    (https://www.youtube.com/watch?v=JIqWOQwWB6g
  24. Huey Cobra Gunships …, p. 11-12 
  25. Raytheon Stinger Missile System,
    (https://web.archive.org/web/20180210181813/https://www.raytheon.com/capabilities/products/stinger
  26. Raytheon TOW Weapons System,
    (https://web.archive.org/web/20180613013057/https://www.raytheon.com/capabilities/products/tow_family
  27. Types of Weapon Cartridges,
    (https://web.archive.org/web/20171206130237/http://www.aosurplus.com/ammo_chart.htm
  28. Fabrique Nationale (FN) Rocket and Machinegun Pod (RMP),
    (https://web.archive.org/web/20180617065317/https://fnamerica.com/products/fn-airborne-pod-systems/fn-rmp/
  29. Fabrique Nationale (FN) Heavy Machinegun Pod 250 (HMP250),
    (https://web.archive.org/web/20180617065505/https://fnamerica.com/products/fn-airborne-pod-systems/fn-hmp250-pod/
  30. US Army Aviation Digest – Oct. 1979 …, p. 33 and 35 
  31. TM 1-1520-236-10 – Technical Manual Operators Manual for Army Model AH-1F Attack Helicopter, Section 4-14,
    (http://www.liberatedmanuals.com/TM-1-1520-236-10.pdf
  32. Huey Cobra Gunships …, p. 38 
  33. Huey Cobra Gunships …, p. 11 
  34. Upgraded Cobra Takes a Bow … 
  35. CPI Inflation Calculator,
    (https://web.archive.org/web/20180619061229/https://data.bls.gov/cgi-bin/cpicalc.pl
  36. Cobra Attack Helicopters Retooled to Fight Fire,
    (https://web.archive.org/web/20180623112708/https://naldc.nal.usda.gov/download/8077/PDF
  37. AW-109 Power Aircraft Cost Summary,
    (https://web.archive.org/web/20180623112749/https://www.conklindd.com/ReportTemp/ACEWebReports/AW109%20Power_2018062222265267.PDF
  38. MD-520N Aircraft Cost Summary,
    (https://web.archive.org/web/20180623112829/https://www.conklindd.com/ReportTemp/ACEWebReports/MD%20520N_2018062222273750.PDF

3 thoughts on “AH-1 Cobra Attack Helicopters for the Philippine Air Force”

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.