The F-5A was an agile, well-performing aircraft, but it had been built primarily with the air-to-ground role in mind and was not well- equipped for air-to-air combat. In particular, it lacked any sort of modern radar equipment and did not even have a lead computing gunsight. Northrop thought that the basic design might make an effective air-to-fighter by adapting it to more powerful engines and by equipping it with radar and other avionics improvements.
In support of this objective, Northrop issued an unsolicited proposal to the USAF for a more capable F-5. However, the Air Force was not about to endorse any such proposal without some sort of demonstration of the capabilities of the aircraft. In the meantime, Northrop had leased the sixth F-5B (63-8445) to General Electric as a testbed for more powerful versions of the J85 turbojet. The aircraft was fitted with a pair of YJ85-GE-21 engines, and became known unofficially as the YF-5B-21. The YJ85-GE-21 added a ninth compressor stage and used titanium rather than steel blades. The peak mass flow was increased from 44 pounds per second to 52 pounds per second. The YF-5B-21 flew for the first time on March 28, 1969, with John Fritz at the controls. During flight testing, the two-position nosewheel developed for the Canadair CF-5 was added, and auxiliary air intake louvered doors were added to the fuselage sides aft of the wings. The increased thrust of the J85-GE021 gave improvements in speed, climb, endurance, and range, while engine handling and throttle response were improved.
In January of 1969, the Air Force had decreed that the J85-GE-21 engine should power the late-production F-5A/B, but Northrop felt that the new engine would be much better put to use to power a new, improved F-5 variant with full air-to-air capability.
Production of the F-5A was still underway when the USAF announced a competition for an IFA (International Fighter Aircraft) to be the F-5A/B's successor. This time, the emphasis would be on the air-superiority role as opposed to the tactical fighter role. Potential customers would be those nations faced with threats from opponents operating late-generation MiG-21s.
On February 26, 1970, the USAF asked for bids from eight companies. Four companies entered the competition--Ling-Temco-Vought with the V-1000, a lightweight development of the F-8 Crusader, Lockeed with the CL-1200 Lancer, a development of the F-104 Starfighter, McDonnell Douglas with a simplified version of the Phantom, and Northrop with an upgraded version of the F-5A/B.
The Northrop entry was initially known as F-5A-21, after its more-powerful General Electric J85-GE-21A turbojets, each rated at 5000 lb.s.t. with afterburning. The air intakes had to be increased in area to provide more air to the engines and the fuselage had to be made somewhat wider to accommodate the extra compressor stages of the J85-GE-21. The use of the new Dash 21 engine also required the installation of CF-5/NF-5-type louvre doors in the rear fuselage to prevent compressor starvation at low forward speeds. These doors were automatically actuated by new pressure sensors.
The fuselage of the F-5A-21 was 15 inches longer and 16 inches wider than that of the F-5A. The extra fuselage space enabled the fitting of larger fuel tanks, increasing internal fuel capacity from 585 to 671 gallons. The new enlarged tanks were lined with reticulated foam to improve battle damage tolerance. The increase in width increased the overall wingspan and contributed to an increase in wing area from 170 square feet to 186 square feet. In order to enhance airflow over the wing at high angles of attack, the wingroot leading-edge extensions (LEX) were refined and enlarged until they represented 4.4 percent of the total wing area.
The F-5A-21 placed emphasis on maneuverability rather than on high speed. It incorporated a system of maneuvering flaps that was based on a similar system that had been used on the Netherlands Air Force's Canadair-built NF-5A/B. Full-span leading-edge flaps worked in conjunction with conventional trailing-edge flaps. The maneuver flaps had four possible settings. The first setting was the fully retracted one, giving a symmetrical aerofoil for supersonic flight. The second was the cruising flight setting, in which the trailing edge drooped 8 degrees. The third was the intermediate setting, which drooped the trailing edge 8 degrees and the leading edge 12 degrees and was used in combat at speeds of up to 600 mph. The last was the landing/takeoff setting, in which full flaps (24 degrees for the leading edge, 20 degrees for the trailing edge) were used. The combination of LEXes and maneuvering flaps was intended to allow the new F-5 to achieve higher angles of attack and thus higher lift with the same amount of drag, or to achieve the same angle of attack with less drag. Unlike the F-5A, which could be equipped with wing-tip tanks, the wing of the F-5E was completely dry.
As compared to the F-5A, the F-5A-21 had a 23 percent improvement in sea-level rate of climb, a 17 percent improvement in sustained turn rate, a 39 percent improvement in turning radius, and a 7 percent in instantaneous turn rate. Maximum speed increased from Mach 1.4 to Mach 1.6 (Mach 1.5 with wingtip AIM-9 missiles fitted).
The F-5A had a rather austere electronics suite, having only the most rudimentary of radar-ranging gunsights. The F-5A-21 was to have a much more advanced avionics fit, which would provide it with much better air-to-air capability. It was to have had an Emerson Electric AN/APQ-159 lightweight miniature X-band pulse radar for air search and range tracking. The fire control radar in the nose was to be slaved to an AN/ASG-31 lead-computing optical gunsight. The lead computing optical gunsight uses input from the radar for the launching of air-to-air missiles or the firing of cannon, and provides roll-stabilized manually-depressible reticle aim reference for the delivery of air-to-ground weapons. The F-5A carried only a simple optical gunsight.
The F-5A-21 incorporated other features that had originally been developed for Canadian, Dutch, and Norwegian F-5As. These included a two-position nose landing gear which increased wing angle of attack on the ground by 3 degrees. This helped to decrease the length of the takeoff run. In addition, the emergency runway arrester hook for short-field use was made standard.
On November 20, 1970, the Northrop entry was declared the winner of the IFA competition, and an initial fixed-price plus incentive contract was placed on December 8 for five development and 325 production aircraft. On December 28, 1970, the F-5A-21 was officially reclassified as F-5E. The aircraft came to be known as *Tiger II*, after the nickname that the F-5A has acquired in Vietnam as a result of the Skoshi Tiger program.
The first F-5E (71-1417) was rolled out at Hawthorne on June 23, 1972 and was sent to Edwards AFB for flight testing The aircraft took off on its maiden flight on August 11, 1972, with Hank Chouteau at the controls. Later that month, the USAF began evaluation tests at Edwards AFB.
The new J85-GE-21 engines proved less reliable than had been hoped and malfunctions lead to a suspension of flight testing between Sept 21 and December 16. Even though flight testing had been resumed, the engines were not declared officially ready until April 25, 1973.
On April 4, 1973, the first Tiger II reached the 425th Tactical Fighter Training Squadron at Chandler AFB in Arizona. This squadron was assigned the task of training for crews that had acquired the F-5E under the Mutual Assistance Pact (MAP).
Northrop took F-5E 72-1390 to the 1973 Paris Salon for demonstration before potential customers. It was spectacularly demonstrated there by North American test pilot Bob Hoover.
MAP and FMS F-5Es were sold with five non-jettisonable external pylons and two wingtip missile launch rails. The centerline position could accommodate a 265-US gallon tank. A RF-5A-type reconnaissance nose and an inflight-refuelling probe were optional items. The standard avionics fit included Hoffman Electronics AN/ARN-56 TACAN, Magnavox AN/ARC-50 UHF, AN/APX-72 IFF/SIF, automatic UHF DF, AN/AIC-18 intercom, SST-181 X-band Skyspot radar transponder and a new solid-state attitude and heading reference system.
The Emerson Electric AN/APQ-159 radar set has a range of about 23 miles and uses a 5-inch CRT display. It is augmented by an AN/ASG-31 lead-computing optical sighting system.
F-5Es were delivered with a bewildering assortment of options, depending on the customer. The Litton LN-33 INS was specified by Iran, Saudi Arabia, and Brazil, and later became virtually standard. Saudi Arabia also specified an Itek/Dalmo Victor ALR-46 RHAWS. Brazil and Chile specified Collins VHF-20 radios and VOR/DME, while Iran, Malaysia, and Taiwan received AN/ARN-84(V)) TACAN. Other options included a semi-conformal Tracor AN/ALE-29 chaff/flare dispenser, Collins DF-206 low-frequency ADF, and Collins ILS and flight director. Northrop even cleared a semi-conformal belly installation of the AN/ALQ-171(V) jammer. Probably the most readily-noticeable customer-specified option was the installation of a dorsal fin fillet to enhance the directional stability of aircraft ordered by Brazil, Chile, Kenya, Mexico, Morocco, Sudan, and Tunisia.
A flattened nose radome was developed during early wind-tunnel testing of RF-5E nose shapes. It was discovered that a flat oval cross-section at the nose eliminated directional stability problems, especially at high angles of attack. This new radome was fitted to F-5Es delvered to Bahrain, some aircraft to delivered to Malaysia and Korea, all aircraft delivered to Mexico, the last Singaporean F-5Es, later Swiss aircraft, a few Taiwanese aircraft, and to later Thai aircraft. This radome was later added to US Navy F-5Es, which were radarless anyway.
Although the F-5E had originally been developed solely for the air-to-air role, two of the earliest FMS customers for the Tiger II (Iran and Saudi Arabia) acquired the aircraft primarily for the ground attack mission. The third F-5E tested the LATAR (Laser-Augmented Target Acquisition and Recognition) system, which was a laser designator, spot tracker, and electro-optical sensor packaged into a streamlined fairing. The aircraft was also tested with the AGM-65 Maverick air-to-surface missile, and the MBB submunition dispenser originally developed for the Panavia Tornado was also tested on the F-5E.
The last two F-5Es off the production line were delivered to Bahrain on January 16, 1987. However, a few more were assembled from spares, the last ones being delivered on June 29, 1989. Northrop built 792 F-5Es, 140 F-5Fs and 12 RF-5Es. F&W in Switzerland built 90 F-5Es and F-5Fs, Korean Air built 68, and AIDC in Taiwan built 380.
71-1417/1421 Northrop F-5E-NO Tiger II 1420 used as prototype RF-5E Tigereye 1417,1418,1420 to Brazil 72-1386/1406 Northrop F-5E Tiger II 1386 to Brazil 1387 to US Navy 1388 to Morocco 1391/1393,1398,1400/1403 to Brazil 73-0846/0888 Northrop F-5E Tiger II to South Vietnam - survivors to USAF, US Navy, South Korea 0885 collided with F-5E 74-1541 on October 5, 1995. 73-0890 Northrop F-5E Tiger II to South Vietnam 73-0892/0902 Northrop F-5E Tiger II all to South Vietnam except 0893/0895, which went to US Navy Survivors to USAF and US Navy 73-0903/0990 Northrop F-5E Tiger II 0903/0932 to Iran 0933/0990 to Iran 73-1626/1646 Northrop F-5E Tiger II 1626,1627,1629/1634,1641/1646 to Korea 1628,1636/1640 to Vietnam 1635 to US Navy 1636,1640 returned to USAF 1640 on display at Kelly AFB. 74-0958/0997 Northrop F-5E Tiger II to Taiwan as 5101/1540 74-1362/1575 Northrop F-5E Tiger II 1362/1444 to Iran 1445/1458 to Malaysia as FM2203/FM2216 1459/1470 to Jordan as 902/913 1471/1479 to South Korea 1480 and 1481 to US Navy as 159881,159882 1482,1483 to South Korea 1485,1494 to South Korea 1495/1504 to Jordan as 914/923 1513/1515 to Brazil 1519 to US Navy 1520/1527 to Ethiopia as 417/424 1528/1531,1533,1536,1537,1537/1541,1544 1545,1547,1554,1556,1558,1563,1564,1568,1570, 1572 to US Navy 1541 w/o Oct 5, 1995 in collision with F-5E 73-0885. 1532,1535,1559,1566 to Tunisia 1543,1549,1551,1553,1560,1569 to Morocco 1574 to Brazil 74-1582/1617 Northrop F-5E Tiger II to Brazil as 4820/4855 75-0314/0373 Northrop F-5E Tiger II for Taiwan as 5141/5200 75-0442/0527 Northrop F-5E Tiger II 0442/456 to Chile as J-800/J-814 0457/0461 to Korea 0462/0490 to Saudi Arabia 0491/0500 to Jordan as 924/933 0501/0527 to Korea 75-0562/0627 Northrop F-5E Tiger II 0562/0572 to Saudi Arabia 0573/0603 to South Korea 0604/0611 to North Yemen 0612,0613,0617 to Morocco 0616 to Thailand 0618/0625 to Jordan as 934/941 0626/0627 to South Korea 76-0471/0490 Northrop F-5E Tiger II for Taiwan as 5201/5220 76-1526/1591 Northrop F-5E Tiger II to Switzerland as J-3001/3066 76-1616/1639 Northrop F-5E Tiger II to Taiwan as 5221/5244 76-1643/1686 Northrop F-5E Tiger II 1643/1663 to South Korea 1664/1676 sold to Thailand 1677/1686 to Keyna as 901/910 77-0366/0379 Northrop F-5E Tiger II to Singapore as 801/820 (only 14 serials used) 77-1767/1777 Northrop F-5E Tiger II 1767/1770 to Singapore as 821/824 1771/1772 to North Yemen 1773/1774 to Jordan as 1145/1146 1775/1776 to North Yemen 1777 to Jordan as 1147 78-0028/0037 Northrop F-5E Tiger II for Taiwan as 5253/5262 78-0770/0773 Northrop F-5E Tiger II to Thailand 78-0789/0801 Northrop F-5E Tiger II to Jordan as 1148/1157 799/801 cancelled 78-0814/0821 Northrop F-5E Tiger II to Indonesia as TS-0501/TS-0508 78-0826/0829 Northrop F-5E Tiger II to Indonesia as TS-0509/TS-0512 78-0865/0875 Northrop F-5E Tiger II to Taiwan as 5263/5273 78-2447 Northrop F-5E Tiger II to Malaysia as FM2217 79-1681/1691 Northrop F-5E Tiger II 1681/1687 to Thailand 1688/1691 to Jordan as 1158/1161 79-1694/1707 Northrop F-5E Tiger II 1694/1697 to Thailand 1698/1701 to Jordan as 1162/1165 1702/1707 to Thailand 79-1717/1720 Northrop F-5E Tiger II to Taiwan as 5274/5277 79-1721/1726 Northrop F-5E Tiger II to Taiwan as 5378/5383 79-1920/1941 Northrop F-5E Tiger II 1920/1925 to Morocco 1926/1931 to Singapore as 830/835 1932/1941 to Morocco 80-0299/0319 Northrop F-5E Tiger II to Taiwan at 5278/5298 80-3501/3537 cancelled contract for Northrop F-5E/F Tiger II 81-0558/0593 Northrop F-5E Tiger II to Korea 81-0614/0625 Northrop F-5E Tiger II to Korea 81-0632/0638 Northrop F-5E Tiger II to Mexico as 4001/4007 81-0823/0857 Northrop F-5E Tiger II 0823/0825 to Mexico as 4008/4010 0826/0857 to Switzerland as J-3067/J-3098 82-0634/0635 Northrop F-5E Tiger II for Tunisia as Y-92501 and Y-92503 82-0636 Northrop F-5E Tiger II for Tunisia as Y-92515 82-0637/0639 Northrop F-5E Tiger II for Tunisia as Y-92505,07,and 09 82-0644/0645 Northrop F-5E Tiger II for Tunisia as Y-92511 and 13 83-0083/0112 Northrop F-5E Tiger II to Taiwan as 5313/5342 84-0183/0184 Northrop F-5E Tiger II to Sudan as 206 and 208 84-0490/0491 Northrop F-5E Tiger II to Malaysia as M29-21 and M29-22 85-0043/0044 Northrop F-5E Tiger II to Bahrain as 688 and 684 85-0057/0058 Northrop F-5E Tiger II to Bahrain as 645,683 85-1586/1595 Northrop F-5E Tiger II 1586/1591 to Singapore as 836/841 1592/1595 to Bahrain as 681,682,686,687 86-0405/0409 Northrop F-5E Tiger II to Singapore as 870/874
Engines: Two General Electric J85-GE-21A turbojets, 3280 lb.s.t. normal maximum thrust, 3500 lb.s.t. maximum military power, 5000 lb.s.t. with afterburning. Performance: Maximum speed: Mach 1.63 at 36,000 feet. Maximum cruising speed without afterburning: Mach 0.98 at 36,000 feet. Stalling speed 143 mph with flaps extended. Service ceiling: 51,800 feet. Initial climb rate: 34,500 feet per minute at combat weight of 13,350 pounds. Takeoff run: 2000 feet at weight of 15,550 pounds. Takeoff run: 5700 feet at maximum takeoff weight of 24,676 pounds. Landing run from 50 feet without braking parachute was 4650 feet at weight of 11,530 pounds. Landing run with brake chute was 2500 feet at 11,530 pounds. Range with maximum fuel was 1543 miles. Combat radius with 5200-pound ordnance load, maximum fuel, and two Sidewinders 195 miles. Combat radius with maximum fuel and 2 Sidewinder missiles 656 miles. Fuel: Total internal fuel capacity of 677 US gallons. One 150 or 275 US gallon drop tank could be carried on the fuselage centerline pylon and on the inboard underwing pylon. bringing total fuel capacity to 1502 US gallons. There is provision for inflight refuelling by means of a detachable probe. Dimensions: wingspan 26 feet 8 inches, length 48 feet 2 inches, height 13 feet 4 inches, wing area 186 square feet. Weights: 9683 pounds empty, 13,350 pounds combat, 15,745 pounds gross, 24,676 pounds maximum takeoff. Armament: Two 20-mm Pontaic (Colt-Browning) M39A2 cannon with 280 rpg in the fuselage nose. Two AIM-9 Sidewinder missiles could be carried at the wingtips. Five pylons, one under the fuselage centerline and four under the wings that can carry up to 7000 pounds of ordnance or fuel tanks.