Comparing the Agusta Westland AW109E Power to the McDonnell Douglas MD520MG Defender

Malaysian Army Air Corps AW109LUH armed with rockets and cannons. Photo courtesy of the Malaysia Flying Herald website

Agusta Westland formally announced the signing of the contract and delivery date of eight AW109E Power as the Philippine Air Force (PAF) next Light Attack Helicopter.¹ I am now comparing these new helicopters with the current light attack helicopter in service with the PAF which is the MD520MG so people can see the difference and get a better appreciation about these new helicopters we are getting.

Some people might've been a disappointed as they were expecting that we would get something similar to the AH-64 Apache as our next attack helicopter, but obviously the AW109E is nothing like that. But it will still be a major improvement for our armed forces, by how much we will try to see.

'Power versus LUH Version'
First though, just a note: We are getting the "AW109 Power" version rather than the "AW109LUH" or "Light Utility Helicopter (LUH)" version of the AW109. The AW109LUH version is usually the armed version used in most armed forces worldwide.

Externally both look the same, but internally the LUH is heavier, has a more powerful engine and can carry slightly less weapons on a maximum internal fuel load. The Power version offer slightly better performance and payload than the LUH version. Here is a quick comparison of the two (sources taken from these sites - ^{2 3}):

The reason the LUH is heavier is because it has more robust systems, like the following:
- Better protection against bullets (Ballistic Tolerance)
- Crashworthy fuel system
- Self-Sealing Fuel Tanks
- Laser/Missile/Radar Warning Systems
- Rear View Mirror

As to why we got this version instead is probably due to budget concerns, with the Power version being cheaper than the LUH version because the latter has more systems. Nevertheless, the A109 Power still maintains some survivability features such as an Engine Compartment Fire Extinguisher system and Reinforced Windshields.

'Aircraft Backgrounds'
The MD520MG is made by the American company “McDonnell Douglas” and is based on the MD500 Defender light, multi-role military helicopter which first flew in 1976. The Defender eventually became a very successful design, going into service in 20 countries and made into 17 different versions including the MD520MG which is the specific version made for the Philippines.⁴

The MG520MG is described as a light attack helicopter first ordered by the Philippines in 1988 and which 33 were delivered between 1990 to 1995.⁵ It has since been a very solid workhorse for the PAF, constantly present in most of its major encounters with insurgents or separatists.

The AW109 is made by the British-Italian company "Agusta Westland" and is based on the A109 commercial multi-purpose helicopter which first flew in 1971. The A109 is another very successful design, even more successful than the MD500 series as it went into service with 24 countries in 24 different versions.⁶

The AW109 Power version is the light commercial helicopter version that AgustaWestland also offers for military markets, but with less systems as discussed in the "Power versus LUH Version" section above. The Power version has two sub-versions, the standard A109E which we will be getting, and the longer "stretched" version, the A109E Grand. Agusta Westland won the bidding held last September 2013 by the PAF for eight light attack helicopters, and first delivery of these aircrafts are expected to be by late 2014.⁷

‘Performance’
Data for each aircraft was derived from various websites.⁸ To measure the performance of both aircrafts I included the measurement for DISC LOADING*. The lower the Disc Loading, the more maneuverable and more effective the aircraft is in terms of maneuverability and the more efficient during hovering, and vice-versa.

SUMMARY
In the five indicators of performance, the AW109E beats the MG520MG except in the areas of Rate of Climb and Disc Loading.

+++ The AW109E Power can fly higher and reach its targets faster by virtue of its higher Service Ceiling and Maximum/Cruising speeds. The MD520MG though is the more maneuverable aircraft and is more fuel-efficient in the hovering phase, as expected as it is a much lighter aircraft.

‘Payload and Range’
For Range, I am using Internal Fuel Fraction (INTFF) as a rough indicator how far each aircraft can go based on the internal fuel available to them.

SUMMARY
INTFF: Huge 46% advantage for the AW109E indicating it could travel 46% further if engine efficiency remain the same.
PAYLOAD: Also favors the AW109E by a commanding 45% (or 228 kg) more payload than the MD520MG.

+++ The AW109E can travel further and with a much heavier payload than the MD520MG. To stress the difference in weight of both aircrafts, note that the EMPTY WEIGHT of the AW109E is HIGHER than the MAXIMUM TAKE OFF WEIGHT of the MD520MG.

An MD-530MG of the Philippine Air Force. Photo courtesy of Wikipedia

‘Avionics’
Aside from the performance, range and payload differences, I feel the most important improvement of the AW109E over the MD520MG is in the area of AVIONICS.

SUMMARY
The AW109E has a modern cockpit, and improved night/limited-adverse weather capability by virtue of its Avionics. It will also be able to deliver its weapons more accurately on target.

'Avionics Advantage'
Depending on which will arrive first into service with the PAF, either these AW109E or the FA-50 Golden Eagle will be the FIRST ATTACK AIRCRAFT of the PAF to have a GLASS COCKPIT and a COMPUTERIZED WEAPONS DELIVERY SYSTEM*. At any rate the AW109E will the FIRST ATTACK HELICOPTER of the PAF to have that honor.

A "Glass Cockpit" means an aircraft cockpit that features electronic or digital instrument displays rather than the traditional style of analog dials and gauges.⁹ The default standard for glass cockpits is the Electronic Flight Instrument System (EFIS) which specifies that there should be at least three digital displays:

• The Primary Flight Display (PFD) which displays information critical to flight such as airspeed, altitude, etc.;
• The Navigation Display (ND) or Multi-Function Display (MFD) showing navigation, weather and other information if necessary;
• And the Engine Indications and Crew Alerting System (EICAS) displaying information about the aircraft's systems such as fuel, engines, etc.¹⁰

Cockpit Comparison: AW109E on the left, MD-520MG on the right

Glass cockpits became en vogue for military aircraft starting in the 1980s, and since we are getting ours only now, one could say that we are behind in this aspect by around two to three decades. The W-3 Sokol we received in 2011 had EFIS-standard Glass Cockpits, but they have been re-assigned from Combat Utility Helicopter (CUH) to Search and Rescue (SAR) missions, while these AW109Es are intended from the outset to serve in the attack role.

The glass cockpit and much better navigation systems will give the AW109E better night and a limited adverse weather capability, making it SAFER to fly and still be able to complete its missions under those conditions.

The MD520MG did have similar capability, but these were limited as the Pilots only had to rely on Night Vision Goggles (NVG) and Global Positioning System (GPS) handsets, a far cry from the Moving Map Display (MMD), Weather Radar and Forward Looking Infra-Red (FLIR) that the AW109E has.

'Computerized Weapons Delivery System'
Not much information is available on the AW109E's Fire Control System (FCS) anywhere in the internet, but I am ASSUMING that it will have a computerized Weapons Delivery System with full range finding capability. If so, then it will enable our pilots to deliver their weapons more accurately.

Before this, pilots had to rely on manual computations and tables based on the ballistics of the weapon they intend to use, and then plan the speed and angle of attack to which to fire their weapons thru a manual sight. That, coupled with some trial and error by looking at where the rounds are hitting and then adjusting as they are firing.

With the AW109E's assumed FCS, systems like Continuously Computed Impact Point (CCIP) will factor in the ballistics of the weapon plus more factors like speed of the aircraft, angle of attack, wind speed, etc. and then show to the pilot on a display where the rounds will impact.

This is done in real-time, hence the pilot only has to guide the aiming point to the target and push the fire button. More accurate weapons delivery means less collateral damage, less cost in terms of ammunition expenditure, and more death and destruction. The PAF likely has not had this type of capability before, not with the MD520MG Defenders, the F-5 Freedom Fighter, F-8 Crusader or even the OV-10 Bronco.

'Parting Shot'
The AW109E compared to the MD520MG will travel farther, and will get there faster and with more weapons. Once it arrives on its destination it will be able to deliver those weapons with more accuracy whether it is day, night or in some adverse weather conditions.

I think that none will be more surprised at what these AW109Es can do than the insurgents and separatists who will likely be the first to be at the receiving end of its weapons.

The MD520MG will still be there, it is a simpler aircraft that is more rugged, easier and cheaper to maintain. A testament to that is the fact that we have been able to keep a couple of them flying after almost two decades now, with a good safety and availability record. But the AW109E will bring our air force truly into the modern age.

A Swedish Air Force AW109LUH. Note the prominent FLIR dome at the bottom rear of the aircraft. Photo courtesy of the Youngester Weapons and Technology website

SOURCES:

GLOSSARY

INTERNAL FUEL FRACTION is the weight of the internal fuel the aircraft compared to its maximum take-off weight, and is expressed by a simple number. Formula used is: (Maximum internal fuel capacity divided by maximum take off weight). (https://web.archive.org/web/20131203071852/http://en.wikipedia.org/wiki/Fuel_fraction)

DISC LOADING is the ratio of its weight to the total main rotor disc area. It is determined by dividing the total helicopter weight by the rotor disc area, which is the area swept by the blades of a rotor. The higher the loading, the more power needed to maintain rotor speed. A low disc loading is a direct indicator of high lift thrust efficiency. (https://web.archive.org/web/20130422122835/https://en.wikipedia.org/wiki/Disk_loading)

COMPUTERIZED WEAPONS DELIVERY SYSTEM or FIRE CONTROL SYSTEM is a number of components working together, usually a gun data computer, a director, and radar, which is designed to assist a weapon system in hitting its target. It performs the same task as a human gunner firing a weapon, but attempts to do so faster and more accurately.
(https://web.archive.org/web/20131113223834/https://en.wikipedia.org/wiki/Fire-control_system)*

1. Philippine Air Force Signs Contract for Eight AW109 Power helicopters,
   (https://web.archive.org/web/20131110032705/http://www.agustawestland.com/news/philippine-air-force-signs-contract-eight-aw109-power-helicopters) 
   


2. AW109 Power Equipment and Technical Data,
   (https://web.archive.org/web/20131024033510/http://www.agustawestland.com/product/aw109-power-1) 
   


3. AW109LUH Equipment and Technical Data,
   (https://web.archive.org/web/20131026074840/http://www.agustawestland.com/product/aw109-luh-0) 
   


4. McDonnell Douglas MD 500 Defender,
   (https://web.archive.org/web/20131006142034/https://en.wikipedia.org/wiki/McDonnell_Douglas_MD_500_Defender) 
   


5. SIPRI data on Arms Transfers to the Philippines from 1965 to 2012, 2013-10_SIPRI_Arms_Transfers_to_Phl 
   


6. AgustaWestland AW109,
   (https://web.archive.org/web/20130724143651/https://en.wikipedia.org/wiki/AgustaWestland_AW109) 
   


7. Italian firm bags P3-B PAF helicopter deal,
   (https://web.archive.org/web/20131109044927/http://www.philstar.com/headlines/2013/10/28/1250261/italian-firm-bags-p3-b-paf-helicopter-deal) 
   


8. MD500 Series Technical Description,
   (https://web.archive.org/web/20131113222714/http://www.mdhelicopters.com/v2/pdfs/products/MD500_Series_TechDescription.pdf) 
   


9. Glass cockpit,
   (https://web.archive.org/web/20131023005326/https://en.wikipedia.org/wiki/Glass_cockpit) 
   


10. Electronic flight instrument system,
    (https://web.archive.org/web/20131027014339/https://en.wikipedia.org/wiki/Electronic_flight_instrument_system)