Ernie P.

My Feedback: (3)

All;

Tailskid has not responded to PM or this forum in three days. The floor is now open to any one who wishes to ask a question. First to post has the floor. Thanks; Ernie P.

perttime

I just found something that might keep us going for a few hours...

What aircraft project?

1) Only 2 aircraft were built
2) It lost the government contract competition
3) It started as a ground-attack project

Ernie P.

My Feedback: (3)

Thanks for stepping up, Perttime. Ground attack? Only two built? That sounded familiar. How about the Northrup YA-9? Thanks; Ernie P.

The Northrop YA-9 was a prototypeattack aircraft developed for the United States Air Force A-X program. The YA-9 was passed over in preference for the Fairchild Republic YA-10 that entered production as the A-10 Thunderbolt II.

Criticism that the U.S. Air Force did not take close air support seriously prompted a few service members to seek a specialized attack aircraft. In the Vietnam War, large numbers of ground-attack aircraft were shot down by small arms, surface-to-air missiles, and low-level anti-aircraft gunfire, prompting the development of an aircraft better able to survive such weapons. Fast jets such as the F-100 Super Sabre, F-105 Thunderchief and F-4 Phantom II proved for the most part to be ineffective for close air support. The A-1 Skyraider was the USAF's primary close air support aircraft.

In mid-1966 the U.S. Air Force formed the Attack Experimental (A-X) program office. On 6 March 1967, the Air Force released a request for information to 21 defense contractors for the A-X. The objective was to create a design study for a low-cost attack aircraft. Discussions with A-1 Skyraider pilots operating in Vietnam and analysis of the effectiveness of current aircraft used in the role indicated the ideal aircraft should have long loiter time, low-speed maneuverability, massive cannon firepower, and extreme survivability; an aircraft that had the best elements of the Ilyushin Il-2, Henschel Hs 129 and Skyraider.

In May 1970, the USAF issued a modified, and much more detailed request for proposals (RFP). The threat of Soviet armored forces and all-weather attack operations had become more serious. Now included in the requirements was that the aircraft would be designed specifically for the 30 mm cannon. The RFP also called for an aircraft with a maximum speed of 460 mph (740 km/h), takeoff distance of 4,000 feet (1,200 m), external load of 16,000 pounds (7,300 kg), 285-mile (460 km) mission radius, and a unit cost of US$1.4 million. During this time, an RFP was released for A-X's 30 mm cannon with requirements for a high rate of fire (4,000 round/minute) and a high muzzle velocity. Six companies submitted proposals to the USAF, with Northrop and Fairchild Republic selected on December 18, 1970 to build prototypes: the YA-9A and YA-10A, respectively. General Electric and Philco-Ford were selected to build and test GAU-8 cannon prototypes.

While turboprops were considered in some designs for the A-X project, turbofans were selected for the flyoff prototypes. The A-9 used the Lycoming F-102 engine, while the A-10 used the GE TF34. The YA-9 took its first flight on 30 May 1972.


Apart from aircraft themselves, the A-X program was also developing a powerful cannon for the winning plane to carry. Eventually, this would result in the GAU-8 Avenger, but for trials, the YA-9 and YA-10 were both equipped with the smaller M61 VulcanGatling gun. By comparison, the A-10 engine location at the tail is less conventional, but offers greater survivability in the case of a hit on the engine area. The double tail of the A-10 also hides the engine infrared and noise signature, and incorporates redundancy in case one of the tails is shot away.

A fly-off of the two prototypes took place between 10 October and 9 December 1972, with the YA-10 declared the winner on 18 January 1973.

The two YA-9 prototypes were subsequently relegated to NASA for continued flight testing before being quickly retired. When retired, the YA-9s' custom-built engines were removed and were later mated to a C-8 Buffalo airframe as part of the NASA-Boeing joint Quiet Short-haul Research Aircraft (QSRA) study into a quiet short-haul commercial aircraft.

perttime

Nooope, not what I had in mind...

I just found something that might keep us going for a few hours...

What aircraft project?

1) Only 2 aircraft were built
2) It lost the government contract competition
3) It started as a ground-attack project
4) There was a new government requirement and they turned the design into a fighter instead

perttime

What aircraft project?

1) Only 2 aircraft were built
2) It lost the government contract competition
3) It started as a ground-attack project
4) There was a new government requirement and they turned the design into a fighter instead
5) it had a crew of 2, seated side-by-side

RCKen

My Feedback: (9)

British COW Biplane???

http://en.wikipedia.org/wiki/COW_Biplane

Ken

Ernie P.

My Feedback: (3)

More of them than I thought. How about the XA-43/XF-87? Thanks; Ernie P.


The Curtiss-Wright XF-87 Blackhawk (previously designated the XP-87) was a prototype American all-weather jet fighter interceptor and the company's last aircraft project. Designed as a replacement for the World War II-era propeller-driven P-61 Black Widow night/interceptor aircraft, the XF-87 lost in government procurement competition to the Northrop F-89 Scorpion. The loss of the contract was fatal to the company; the Curtiss-Wright Corporation closed down its aviation division, selling its assets to North American Aviation.

The aircraft started life as a project for an attack aircraft, designated XA-43. When the United States Army Air Forces issued a requirement for a jet-powered all-weather fighter in 1945, the design was reworked for that request.

The XP-87 was a large mid-wing aircraft with four engines paired in underwing pods, with a mid-mounted tailplane and tricycle undercarriage. Two crew members (pilot and radio operator) sat side by side under a single canopy. Armament was to be a nose-mounted, powered turret containing four 20 mm (0.79 in) cannon, but this was never fitted to the prototypes.

The first flight of the XF-87 Blackhawk was on 1 March 1948. Although the top speed was slower than expected, the aircraft was otherwise acceptable, and the newly-formed (in September 1947) United States Air Force placed orders for 57 F-87A fighters and 30 RF-87A reconnaissance aircraft just over a month later. Since the performance problems were due to lack of power, the four Westinghouse XJ34-WE-7turbojets of the prototypes were to be replaced by two General Electric J47 jets in production models. One of the two XF-87 prototypes was to be converted to the new powerplants for test purposes.

At this point, the USAF decided that the Northrop F-89 Scorpion was a more promising aircraft. The F-87 contract was cancelled on 10 October 1948, and both prototypes were scrapped.

perttime

Curtiss XF-87 Blackhawk is correct!

The last aircraft design that Curtiss built.
http://www.aviastar.org/air/usa/curtiss_f-87.php
http://en.wikipedia.org/wiki/Curtiss...F-87_Blackhawk
Next, I was going to mention that the second prototype was to have fewer engines than the first one.

Your turn, Ernie P.

Ernie P.

My Feedback: (3)

Thanks, Perttime. It has always puzzled me how Curtiss aircraft went from being the leader in aviation to an "also ran" in only a few years. Maybe Glenn Curtiss just got old and left the company; and the company only survived until the team he had assembled retired, died or moved on? Let's see if this keeps everyone amused for a while. Thanks; Ernie P.


Question: What model, of what warbird, do I describe?

Clues:

(1) Thousands were built, but we’re only interested in three of those thousands.

(2) These three were the only representatives of a completely different model of the basic aircraft.

Ernie P.

My Feedback: (3)

Evening clue. Thanks; Ernie P.


Question: What model, of what warbird, do I describe?

Clues:

(1) Thousands were built, but we’re only interested in three of those thousands.

(2) These three were the only representatives of a completely different model of the basic aircraft.

(3) The basic model was noted for being a pretty hot aircraft.

Ernie P.

My Feedback: (3)

Morning clue. Thanks; Ernie P.


Question: What model, of what warbird, do I describe?

Clues:

(1) Thousands were built, but we’re only interested in three of those thousands.

(2) These three were the only representatives of a completely different model of the basic aircraft.

(3) The basic model was noted for being a pretty hot aircraft.

(4) It flew very fast and very high.

perttime

de Havilland Mosquito FB Mk 21 : Canadian version of the Mosquito FB Mk VI fighter-bomber aircraft. Powered by two 1,460 hp (1,090 kW) Rolls-Royce Merlin 31 piston engines, three built.
...thousands of Mosquitoes were built ... but I don't think it was "completely different".

Ernie P.

My Feedback: (3)

A good and well thought out answer, Perttime; but not the plane I'm looking for. BTW; to clarify: I'm not saying the three aircraft were "completely different". I'm saying they were different enough to justify a "completely different" model number. Maybe this next clue will help. Thanks; Ernie P.


Question: What model, of what warbird, do I describe?

Clues:

(1) Thousands were built, but we’re only interested in three of those thousands.

(2) These three were the only representatives of a completely different model of the basic aircraft.

(3) The basic model was noted for being a pretty hot aircraft.

(4) It flew very fast and very high.

(5) So, naturally enough, it was modified to fly even faster and higher.

Ernie P.

My Feedback: (3)

Morning clue. Thanks; Ernie P.


Question: What model, of what warbird, do I describe?

Clues:

(1) Thousands were built, but we’re only interested in three of those thousands.

(2) These three were the only representatives of a completely different model of the basic aircraft.

(3) The basic model was noted for being a pretty hot aircraft.

(4) It flew very fast and very high.

(5) So, naturally enough, it was modified to fly even faster and higher.

(6) The basic reason for the entire program was to reduce training costs.

Ernie P.

My Feedback: (3)

Evening clue. Thanks; Ernie P.


Question: What model, of what warbird, do I describe?

Clues:

(1) Thousands were built, but we’re only interested in three of those thousands.

(2) These three were the only representatives of a completely different model of the basic aircraft.

(3) The basic model was noted for being a pretty hot aircraft.

(4) It flew very fast and very high.

(5) So, naturally enough, it was modified to fly even faster and higher.

(6) The basic reason for the entire program was to reduce training costs.

(7) These three were trainers.

Ernie P.

My Feedback: (3)

Morning clue. Thanks; Ernie P.


Question: What model, of what warbird, do I describe?

Clues:

(1) Thousands were built, but we’re only interested in three of those thousands.

(2) These three were the only representatives of a completely different model of the basic aircraft.

(3) The basic model was noted for being a pretty hot aircraft.

(4) It flew very fast and very high.

(5) So, naturally enough, it was modified to fly even faster and higher.

(6) The basic reason for the entire program was to reduce training costs.

(7) These three were trainers.

(8) And they carried a new guidance control system.

perttime

Lockheed NF-104A?
mixed power, high-performance, supersonic aerospace trainer that served as a low-cost astronaut training vehicle for the X-15 and projected X-20 Dyna-Soar programs.

Ernie P.

My Feedback: (3)

Man; once perttime gets on the trail, he sticks with it. You are, of course, correct Sir! Good job! What is your question? Thanks; Ernie P.


Question: What model, of what warbird, do I describe?

Clues:

(1) Thousands were built, but we’re only interested in three of those thousands.

(2) These three were the only representatives of a completely different model of the basic aircraft.

(3) The basic model was noted for being a pretty hot aircraft.

(4) It flew very fast and very high.

(5) So, naturally enough, it was modified to fly even faster and higher.

(6) The basic reason for the entire program was to reduce training costs.

(7) These three were trainers.

(8) And they carried a new guidance control system.

(9) Stories abound as to how the basic aircraft’s wings would almost melt at top speed.

(10) The first of the three was damaged, almost destroyed, in an inflight engine failure.

(11) The third was famously destroyed in a crash.

(12) The second was retired and is on display today.

The Lockheed NF-104A was an American mixed power, high-performance, supersonic aerospace trainer that served as a low-cost astronaut training vehicle for the X-15 and projected X-20 Dyna-Soar programs.
Three aircraft were modified from existing Lockheed F-104A airframes and served with the Aerospace Research Pilots School between 1963 and 1971, the modifications included a small supplementary rocket engine and a reaction control system for flight in the upper atmosphere. During the test program the maximum altitude reached was over 120,000 ft (36,600 m). One of the aircraft was destroyed in an accident while being flown by Chuck Yeager. The accident was depicted in the book The Right Stuff and the film of the same name.

With the advent of manned spaceflight in the early 1960s, the United States Air Force Experimental Flight Test Pilot's School at Edwards Air Force Base was renamed the Aerospace Research Pilots School (ARPS), with the emphasis on training moving away from the traditional test pilot course to a more spaceflight oriented curriculum.
Initial use of unmodified F-104 aircraft
A number of standard production F-104 Starfighters were obtained (including F-104D two-seat versions) and used by the ARPS to simulate the low lift/high drag glide approach path profiles of the X-15 and the projected X-20 Dyna-Soar program. These maneuvers were commenced at 12,000 ft (3,700 m) where the F-104 engine was throttled back to 80% power; and with the flaps, speedbrakes and landing gear extended, the aircraft was established in a 30˚ dive with a pull-out for the landing flare starting at 1,500 ft (460 m) above the ground. These glide approaches gave little room for error.
Reaction Control System


JF-104 during RCS testing.
It was realized that normal aircraft control surfaces had little or no effect in the thin atmosphere of the stratosphere and that any aircraft operating at extremely high altitudes would need to be equipped with a reaction control system (RCS). A modified version of the Bell X-1 was used for initial RCS tests, but was grounded after technical problems and was replaced with a NASA-modified Lockheed F-104A (55-2961) in 1959 which carried RCS systems on its wing tips and in the fuselage nose. This aircraft (designated JF-104) achieved a maximum altitude of 83,000 ft (25,000 m) during the test program. Pilots who flew this aircraft included Neil Armstrong who gained valuable experience in using the RCS. Pilots complained that the instrument displays were difficult to read and were not accurate enough for the critical zoom climb profiles required to reach high altitudes.

Lockheed contract
Lockheed was awarded a contract by the USAF to modify three F-104A aircraft for the dedicated role of aerospace trainer (AST) in 1962. The airframes were taken out of storage at AMARC and transported to the company factory for modification.

The F-104A design was already established as a lightweight, high performance aircraft; but for the AST project, emphasis was placed on removing unnecessary equipment, fitting a rocket engine to supplement the existing jet engine, fitting an onboard RCS system and improving the instrumentation required. The following details give the main differences between the production version and the AST:

Wing
The wingspan of the NF-104A was increased by adding tip extensions to the existing planform. This modification was needed to house the RCS roll control thrusters and would also decrease the type's wing loading.

Tail surfaces
The vertical fin and rudder were replaced by the larger area versions from the two-seat F-104 and were structurally modified to allow installation of the rocket engine.

Fuselage
The fiberglass nose radome was replaced with an aluminum skin and housed the pitch and yaw RCS thrusters. The air intakes originally designed by Ben Rich were of the same fixed geometry as the F-104A but included extensions to the inlet shock cones for optimum jet engine operation at higher Mach numbers. Internal fuselage differences included provision for rocket fuel oxidizer tanks, deletion of the M61 Vulcan cannon, Radar equipment and unnecessary avionics. A nitrogen tank was installed for cabin pressurization purposes, this was required as there would be no bleed air available from the engine after its normal and expected cutoff in the climb phase. Contrary to popular misconception, the jet engine was not allowed to flameout but had to be gradually throttled down and then cutoff as EGT temperatures ramped up towards the danger point for the turbojet's integrity.

Rocket engine
In addition to the standard J79 jet engine a Rocketdyne AR2-3 rocket engine was fitted at the base of the vertical fin. This engine burned a mixture of JP-4 jet fuel and 90% hydrogen peroxide oxidizer solution. The NF-104 carried enough oxidizer for approximately 100 seconds of rocket engine operation. The thrust level could be adjusted to maximum or approximately half power by the pilot using an additional throttle lever on the left side of the cockpit.

Reaction Control System
The Reaction Control System (RCS) consisted of eight pitch/yaw motors (four for each axis) and four roll motors. They used the same kind of hydrogen peroxide fuel as the main rocket engine from a dedicated 155 lb (70 kg) fuel tank and were controlled by the pilot using a handle mounted in the instrument panel. The pitch/yaw motors were rated at 113 lbf (500 N) thrust each and the roll motors were rated at 43 lbf (190 N) thrust.
Typical flight profile

Ernie P.

My Feedback: (3)

Man; once perttime gets on the trail, he sticks with it. You are, of course, correct Sir! Good job! What is your question? Thanks; Ernie P.


Question: What model, of what warbird, do I describe?

Clues:

(1) Thousands were built, but we’re only interested in three of those thousands.

(2) These three were the only representatives of a completely different model of the basic aircraft.

(3) The basic model was noted for being a pretty hot aircraft.

(4) It flew very fast and very high.

(5) So, naturally enough, it was modified to fly even faster and higher.

(6) The basic reason for the entire program was to reduce training costs.

(7) These three were trainers.

(8) And they carried a new guidance control system.

(9) Stories abound as to how the basic aircraft’s wings would almost melt at top speed.

(10) The first of the three was damaged, almost destroyed, in an inflight engine failure.

(11) The third was famously destroyed in a crash.

(12) The second was retired and is on display today.

The Lockheed NF-104A was an American mixed power, high-performance, supersonic aerospace trainer that served as a low-cost astronaut training vehicle for the X-15 and projected X-20 Dyna-Soar programs.
Three aircraft were modified from existing Lockheed F-104A airframes and served with the Aerospace Research Pilots School between 1963 and 1971, the modifications included a small supplementary rocket engine and a reaction control system for flight in the upper atmosphere. During the test program the maximum altitude reached was over 120,000 ft (36,600 m). One of the aircraft was destroyed in an accident while being flown by Chuck Yeager. The accident was depicted in the book The Right Stuff and the film of the same name.

With the advent of manned spaceflight in the early 1960s, the United States Air Force Experimental Flight Test Pilot's School at Edwards Air Force Base was renamed the Aerospace Research Pilots School (ARPS), with the emphasis on training moving away from the traditional test pilot course to a more spaceflight oriented curriculum.
Initial use of unmodified F-104 aircraft
A number of standard production F-104 Starfighters were obtained (including F-104D two-seat versions) and used by the ARPS to simulate the low lift/high drag glide approach path profiles of the X-15 and the projected X-20 Dyna-Soar program. These maneuvers were commenced at 12,000 ft (3,700 m) where the F-104 engine was throttled back to 80% power; and with the flaps, speedbrakes and landing gear extended, the aircraft was established in a 30˚ dive with a pull-out for the landing flare starting at 1,500 ft (460 m) above the ground. These glide approaches gave little room for error.
Reaction Control System


JF-104 during RCS testing.
It was realized that normal aircraft control surfaces had little or no effect in the thin atmosphere of the stratosphere and that any aircraft operating at extremely high altitudes would need to be equipped with a reaction control system (RCS). A modified version of the Bell X-1 was used for initial RCS tests, but was grounded after technical problems and was replaced with a NASA-modified Lockheed F-104A (55-2961) in 1959 which carried RCS systems on its wing tips and in the fuselage nose. This aircraft (designated JF-104) achieved a maximum altitude of 83,000 ft (25,000 m) during the test program. Pilots who flew this aircraft included Neil Armstrong who gained valuable experience in using the RCS. Pilots complained that the instrument displays were difficult to read and were not accurate enough for the critical zoom climb profiles required to reach high altitudes.

Lockheed contract
Lockheed was awarded a contract by the USAF to modify three F-104A aircraft for the dedicated role of aerospace trainer (AST) in 1962. The airframes were taken out of storage at AMARC and transported to the company factory for modification.

The F-104A design was already established as a lightweight, high performance aircraft; but for the AST project, emphasis was placed on removing unnecessary equipment, fitting a rocket engine to supplement the existing jet engine, fitting an onboard RCS system and improving the instrumentation required. The following details give the main differences between the production version and the AST:

Wing
The wingspan of the NF-104A was increased by adding tip extensions to the existing planform. This modification was needed to house the RCS roll control thrusters and would also decrease the type's wing loading.

Tail surfaces
The vertical fin and rudder were replaced by the larger area versions from the two-seat F-104 and were structurally modified to allow installation of the rocket engine.

Fuselage
The fiberglass nose radome was replaced with an aluminum skin and housed the pitch and yaw RCS thrusters. The air intakes originally designed by Ben Rich were of the same fixed geometry as the F-104A but included extensions to the inlet shock cones for optimum jet engine operation at higher Mach numbers. Internal fuselage differences included provision for rocket fuel oxidizer tanks, deletion of the M61 Vulcan cannon, Radar equipment and unnecessary avionics. A nitrogen tank was installed for cabin pressurization purposes, this was required as there would be no bleed air available from the engine after its normal and expected cutoff in the climb phase. Contrary to popular misconception, the jet engine was not allowed to flameout but had to be gradually throttled down and then cutoff as EGT temperatures ramped up towards the danger point for the turbojet's integrity.

Rocket engine
In addition to the standard J79 jet engine a Rocketdyne AR2-3 rocket engine was fitted at the base of the vertical fin. This engine burned a mixture of JP-4 jet fuel and 90% hydrogen peroxide oxidizer solution. The NF-104 carried enough oxidizer for approximately 100 seconds of rocket engine operation. The thrust level could be adjusted to maximum or approximately half power by the pilot using an additional throttle lever on the left side of the cockpit.

Reaction Control System
The Reaction Control System (RCS) consisted of eight pitch/yaw motors (four for each axis) and four roll motors. They used the same kind of hydrogen peroxide fuel as the main rocket engine from a dedicated 155 lb (70 kg) fuel tank and were controlled by the pilot using a handle mounted in the instrument panel. The pitch/yaw motors were rated at 113 lbf (500 N) thrust each and the roll motors were rated at 43 lbf (190 N) thrust.
Typical flight profile

Ernie P.

My Feedback: (3)

A bit more info on the NF-104A. Thanks; Ernie P.


Typical flight profile


Chuck Yeager in the cockpit of an NF-104A, 4 December 1963
The NF-104A was able to reach great altitudes through a combination of zoom climbing (trading speed for altitude) and use of the rocket engine. A typical mission involved a level acceleration at 35,000 ft (11,000 m) to Mach 1.9 where the rocket engine would be ignited, and on reaching Mach 2.1 the aircraft would be pitched up to a climb angle of 50-70° by carefully applying a load equal to 3.5 g. The J79 afterburner would start to be throttled down at approximately 70,000 ft (21,000 m) followed shortly after by manual fuel cutoff of the main jet engine itself around 85,000 ft (26,000 m) to prevent fast rising engine temperatures from damaging the turbojet. After continuing over the top of its ballistic arc the NF-104 would descend back into denser air where the main engine could be restarted using the windmill restart technique for recovery to a landing.

First NF-104A
The first NF-104A (USAF 56-0756) was accepted by the USAF on 1 October 1963. It quickly established a new unofficial altitude record of 118,860 ft (36,230 m) and surpassed this on 6 December 1963 by achieving an altitude of 120,800 ft (36,800 m). It suffered an inflight rocket motor explosion in June 1971. Although the pilot was able to land safely, the damaged aircraft was retired and marked the end of the NF-104 project. This aircraft was reported as scrapped.

Second NF-104A


NF-104A Tail Number 760 at the USAF Test Pilot School.
WikiMiniAtlas
34°55′0.68″N 117°54′2.40″W / 34.9168556°N 117.9006667°W / 34.9168556; -117.9006667

The second NF-104A (USAF 56-0760) was accepted by the USAF on 26 October 1963. After retirement, this aircraft was mounted on a pole outside the U.S. Air Force Test Pilot School at Edwards Air Force Base and can still be seen there today. The extended wing tips, RCS metal nose cone and other parts from 56-0760 were loaned to Darryl Greenamyer for his civilian aviation record attempts using a highly modified F-104. When he was forced to eject during a record flight, his aircraft was destroyed and the parts were never returned.

Third NF-104A
The third NF-104A (USAF 56-0762) was delivered to the USAF on 1 November 1963, and was destroyed in a crash while being piloted by Chuck Yeager on 10 December 1963. This accident was depicted in the book The Right Stuff and the film of the same name; although the aircraft used for filming was a standard F-104G flying with its wingtip fuel tanks removed, but otherwise lacking any of the NF-104A's modifications, most visibly the rocket engine pod at the base of the vertical stabilizer.

NF-104A
Main article: Lockheed NF-104A
Three demilitarized versions with an additional 6,000 lbf (27 kN) Rocketdyne LR121/AR-2-NA-1 rocket engine, used for astronaut training at altitudes up to 120,800 ft (36,820 m).

perttime

mmmm..... Something was ringing bells, so I decided to check if they made some specials out of the F-104.

Oh Dear. I'll try to pick something to post pretty soon...

perttime

It is an aircraft ...

1) It seems to fascinate a lot of people.
2) It did not go into large scale production.

Top_Gunn

My Feedback: (6)

Spruce Goose?

perttime

It is an aircraft ...

1) It seems to fascinate a lot of people.
2) It did not go into large scale production.
3) prototypes and pre-production aircraft were built. Not quite sure about numbers - about 20, or so.

perttime

It is an aircraft ...

1) It seems to fascinate a lot of people.
2) It did not go into large scale production.
3) Prototypes and pre-production aircraft were built. Not quite sure about numbers - about 20, or so.
4) A dozen of the aircraft were used in a defensive role.