The US Army officially remains undecided, but it's not for a lack of options. There are instead plenty of potential heirs of the venerable OH-58D Kiowa Warrior, the army's "interim" armed scout since the late-1960s. Here are some pro's and con's of the five main contenders in no particular order.
1. Sikorsky S-97 Raider
PROs: The coaxial-rotor, compound S-97 helicopter is designed to be at least twice as fast as the OH-58D. Sikorsky has self-funded the building and testing of prototypes that will fly in 2014. The S-97's 225kt speed would allow the armed scout to be compatible with the army's vision for a high-speed replacement for the UH-60 Black Hawk and AH-64 Apache by 2030.
CONs: Record-breaking flights by the X2 demonstrator are still no substitute for a proven aircraft. The S-97 will need a multi-billion dollar development program even after Sikorsky flies the S-97 prototypes in three years. The current budget climate makes it difficult to launch an all-new helicopter development program, and the army's track record with new armed scouts may not inspire confidence in the Office of the Secretary of Defense.
2. OH-58F Block II
PROs: The OH-58F cockpit and sensor upgrades (CASUP) eliminate the biggest maintenance and obsolescence problems with the current airframe. Bell Helicopter's Block II proposal, meanwhile, addresses the Kiowa Warrior's biggest performance shortfall. The Block II adds the 1,021shp HTS900-2 engine or a more powerful Rolls-Royce Model 250-C30R, allowing the OH-58 to hover at 6,000ft with temperatures above 95 degrees Fahrenheit. Training and maintenance pipelines already exist within the army.
CONs: Even if Bell can deliver the re-engined OH-58F Block II on time and on schedule, the army is still left with the airframe it never really wanted in the first place for at least another 15 years. The army would have no options in 2025 except to replace the OH-58, but that requirement may compete for funding with the Black Hawk/Apache replacement program.
3. EADS North America AAS-72X
PROs: The armed scout version of the Eurocopter EC-145 leverages the army's investment in the UH-72A Lakota light utility helicopter. As a twin-engine helicopter, the AAS-72X is more powerful, versatile and modern than the OH-58D, yet remains very agile. On a demonstration flight yesterday, the EADS pilot landed the TDA-1 demonstrator in a clearing with 4ft between the tips of the rotor blade and tree branches.
CONs: The AAS-72X is not a high-speed helicopter, potentially leaving the army with a mismatch between the armed scout and its vision for a post-2030 fleet. The army would have to replace its training and logistics pipeline for armed scout units (although EADS argues this must be done eventually anyway). The AAS-72X offers a slightly larger target than the OH-58 without the stealth of the RAH-66 Comanche or the speed of the S-97, but EADS says the added performance and safety of the twin engines and the versatility of the larger cabin are worth the trade-off.
4. Boeing AH-6i or AH-6S
PROs: Boeing's proposals based on an international or stretched version are based on the special operations-proven AH-6M Little Bird, but adapted to meet the army's requirements for hovering at high-altitude in extremely hot temperatures. The AH-6 also "wakes up in the morning thinking it's an Apache," Boeing business development vice president Mike Burke says, with more than 80% of the AH-64's avionics system installed. The AH-6 has the smallest footprint, making it less of a target.
CONs: The AH-6 design comes from the same legacy as the OH-58. Indeed, the OH-6 Cayuse was originally selected as the army's armed scout in 1967, but production problems at Hughes forced the army to switch to the OH-58A a year later. Boeing officials say the new AH-6 models can meet all of the army's requirements, but it's not clear how much growth potential is left in the airframe.
5. AVX Corp OH-58D
PROs: Although seemingly the most radical of the armed scout proposals, the start-up AVX Corp's concept for modifying existing OH-58Ds with a coaxial rotor and dual-ducted fans should cost only $1 million more per aircraft, says Troy Gaffey, an AVX founder and former chief engineer at Bell. For that investment, the army gets a slight bump in cruise speed to 120kt, hover out of ground effect at 6,000ft at 95degF with a 5,500lb load and 3.1h of endurance.
CONs: AVX officials acknowledge that the lack of an existing concept demonstrator hurts their chances, but they are "close" to signing financing deals with possible investors. The concept remains unproven, with no similar propulsion configurations in service anywhere in the world.
1. Sikorsky S-97 Raider
PROs: The coaxial-rotor, compound S-97 helicopter is designed to be at least twice as fast as the OH-58D. Sikorsky has self-funded the building and testing of prototypes that will fly in 2014. The S-97's 225kt speed would allow the armed scout to be compatible with the army's vision for a high-speed replacement for the UH-60 Black Hawk and AH-64 Apache by 2030.CONs: Record-breaking flights by the X2 demonstrator are still no substitute for a proven aircraft. The S-97 will need a multi-billion dollar development program even after Sikorsky flies the S-97 prototypes in three years. The current budget climate makes it difficult to launch an all-new helicopter development program, and the army's track record with new armed scouts may not inspire confidence in the Office of the Secretary of Defense.
2. OH-58F Block II
PROs: The OH-58F cockpit and sensor upgrades (CASUP) eliminate the biggest maintenance and obsolescence problems with the current airframe. Bell Helicopter's Block II proposal, meanwhile, addresses the Kiowa Warrior's biggest performance shortfall. The Block II adds the 1,021shp HTS900-2 engine or a more powerful Rolls-Royce Model 250-C30R, allowing the OH-58 to hover at 6,000ft with temperatures above 95 degrees Fahrenheit. Training and maintenance pipelines already exist within the army. CONs: Even if Bell can deliver the re-engined OH-58F Block II on time and on schedule, the army is still left with the airframe it never really wanted in the first place for at least another 15 years. The army would have no options in 2025 except to replace the OH-58, but that requirement may compete for funding with the Black Hawk/Apache replacement program.
3. EADS North America AAS-72X
PROs: The armed scout version of the Eurocopter EC-145 leverages the army's investment in the UH-72A Lakota light utility helicopter. As a twin-engine helicopter, the AAS-72X is more powerful, versatile and modern than the OH-58D, yet remains very agile. On a demonstration flight yesterday, the EADS pilot landed the TDA-1 demonstrator in a clearing with 4ft between the tips of the rotor blade and tree branches. CONs: The AAS-72X is not a high-speed helicopter, potentially leaving the army with a mismatch between the armed scout and its vision for a post-2030 fleet. The army would have to replace its training and logistics pipeline for armed scout units (although EADS argues this must be done eventually anyway). The AAS-72X offers a slightly larger target than the OH-58 without the stealth of the RAH-66 Comanche or the speed of the S-97, but EADS says the added performance and safety of the twin engines and the versatility of the larger cabin are worth the trade-off.
4. Boeing AH-6i or AH-6S
PROs: Boeing's proposals based on an international or stretched version are based on the special operations-proven AH-6M Little Bird, but adapted to meet the army's requirements for hovering at high-altitude in extremely hot temperatures. The AH-6 also "wakes up in the morning thinking it's an Apache," Boeing business development vice president Mike Burke says, with more than 80% of the AH-64's avionics system installed. The AH-6 has the smallest footprint, making it less of a target.CONs: The AH-6 design comes from the same legacy as the OH-58. Indeed, the OH-6 Cayuse was originally selected as the army's armed scout in 1967, but production problems at Hughes forced the army to switch to the OH-58A a year later. Boeing officials say the new AH-6 models can meet all of the army's requirements, but it's not clear how much growth potential is left in the airframe.
5. AVX Corp OH-58D
PROs: Although seemingly the most radical of the armed scout proposals, the start-up AVX Corp's concept for modifying existing OH-58Ds with a coaxial rotor and dual-ducted fans should cost only $1 million more per aircraft, says Troy Gaffey, an AVX founder and former chief engineer at Bell. For that investment, the army gets a slight bump in cruise speed to 120kt, hover out of ground effect at 6,000ft at 95degF with a 5,500lb load and 3.1h of endurance. CONs: AVX officials acknowledge that the lack of an existing concept demonstrator hurts their chances, but they are "close" to signing financing deals with possible investors. The concept remains unproven, with no similar propulsion configurations in service anywhere in the world.
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