Navaho G-26 Launch Credit - Tom Johnson Media Gallery

The Navaho G-26 was a 2/3 scale test version of the operational Navaho G-38. The Navaho program was cancelled on 13 July 1957, but already-built G-26 test missiles were flown to the end of 1958.

Development History

North American had been developing a 1600-km range, Mach 3 missile for the US Air Force since March 1946. The vehicle started out as a derivative of the German A9 boost-glide vehicle, but soon developed completely revised aerodynamics, guidance, and improved propulsion. In February 1948 this project was redefined by the customer as only the first step of a revised three-phase program for a family of vehicles using a rocket booster and ramjet cruise. Track, air, and vertical pad launch were to be studied. Phase two would produce a missile that could carry a 1350 kg warhead to a 3200 to 4800 km range. By July 1948 the preferred long-range Navaho configuration was a delta-winged, recoverable aircraft-type booster looking very much like the B-70 bomber of the 1960's or the reusable boosters of the original space shuttle designs. The cruise stage used a single enormous ramjet engine with a nose intake.

In May 1949 North American settled on a revised design for the long-range versions of the Navaho. It consisted of a tandem in-line boost stage with a single-ramjet cruise stage atop it. In April 1950 the Air Force canceled the 1600-km range Phase I version of the Navaho. Formal redirection of the program came in July 1950. The final missile intercontinental missile would be developed in a new three-phase program. In Phase 2, the G-26 test vehicle, a 2/3 scale version, would test the vertical launch booster, and a steel-structure ramjet-powered cruise vehicle that would reach Mach 2.75 and a range of 2300 km. By March 1951 the development of the 333 kN XLR-43-NA-1 rocket engine for the now-canceled 1600-km range version was completed; but this was just a way-station to the more powerful LR-71-NA-1 530 kN engine required for the Phase II and III missiles.

The course of 1952 saw a wide range of testing activities. A 20-inch diameter ramjet, a subscale version of the 40-inch engine for the Navaho, was flown on Lockheed's X-7 rocket. Of the seven launches, only one was completely successful, and two partially successful. The G-26 version of Navaho reached the mock-up stage. In June a test version of the 540 kN combustion chamber for missile was run. This was the most powerful ever tested, but still used the double-walled combustion chamber design of the LR43 rather than the brazed tubular wall construction planned for the production LR71. But the first complete prototype was first operated on 19 November. By the end of the year the drawings for the G-26 were released to the shop.

On 23 December the USAF released the full-scale development contract for the Navaho G-26, consisting of 10 cruise missiles, 13 boosters, and five N-6 stellar-inertial navigation systems (early flights would be radio-controlled). First delivery was scheduled for 1953 and first launch February 1956.

But early in 1953 another technical improvement was deemed necessary, and this would impact the schedule just agreed. North American's rocket group had begun a Rocket Engine Advancement Program, to identify improved rocket technology. One early conclusion was that the performance and logistics could be significantly improved by shifting from alcohol to kerosene fuel. The decision was made to change the propellants for both the Navaho G-26 test vehicle and the G-38 production booster. The LR71 engine, improved and modified to burn kerosene, would be designated LR83. This meant a delay to Navaho, but would be the basic engine that would power the Thor, Jupiter, Atlas, Saturn I, and Delta rockets into the next century. It should be noted that most references state that the Navaho was flown with the LR71 alcohol engine; but it is quite clear that it flew with the LR83 kerosene engine, or at least with LR71 engines modified to burn kerosene.

North American also began operations at Cape Canaveral in 1953, building two missile assembly buildings, a vertical launch facility for the G-26 (LC9) and a 70 m x 3000 m landing strip (the 'Skid Strip') to recover the reusable G-26 test vehicles. North American tripled its field office staff at the Cape from 22 to 77 people in 1954. It also began installing equipment in the guidance laboratory, the blockhouse and the Navaho flight control building even before construction of those facilities was completed. N-6 navigation system flight testing began aboard a T-29 in May 1954.

On 11 January 1955 the Air Force expressed its confidence in the missile by placing the second G-26 second production contract. This added 12 more cruise stages, 21 boosters, and 6 N6 navigation systems, bringing the total procured to 22 cruise stages, 34 boosters, and 11 navigation systems. Support facilities were at the Cape were completed in the last half of 1955. By the middle of 1956, North American had 605 people working on the Navaho program at the Cape, but problems with the auxiliary power unit delayed the Navaho G-26's first launch for six months. When the first vehicle finally made it into the air, it exploded 26 seconds into the flight. Three more Navahos were launched over the next seven months with equally dismal results. In addition to those failures, the first in a series of 2,800 km long auto-navigator test flights was attempted ten times in the first three months of 1957 without a single launch.

More promising were successful static tests of the booster rockets and North American's isolation of problem areas revealed in the first four flights. But while the "never-go-Navaho" sat on the pad or failed in flight, the first Jupiter, Thor, and Atlas ballistic missiles began test in the spring of 1957. They were equally unsuccessful at first, but a Jupiter made a full-range 2100-km flight on 31 May. The Army had already demonstrated the necessary re-entry vehicle technology on launches of the 'Jupiter-A' multi-stage versions of the Redstone. It was clear that these ballistic missiles, each little more complex than the booster stage of Navaho alone, could deliver a nuclear warhead over the same ranges - at seven times the speed.

But it was still a surprise when Air Force Headquarters terminated the Navaho development program on 12 July 1957. 4,705 employees were laid off the day the termination notice was received via an announcement over the public address system to "stop what you are doing, proceed to the nearest exit, and deposit your badge in the bin indicated". By the end of the month the total staff laid off at North American alone amounted to 15,600 employees.

Because the auto-navigator showed promise for use on other missiles, the Air Force authorized continuation of flight test of existing assets. Engineering staff was kept on at Cape Canaveral to launch the five completed G-26 missiles, at a total cost of $4.9 million. These were flown through February 1958, and were somewhat more successful than the earlier series, with one missile managing to reach a range of 2000 km before its ramjets failed.

Seven further completed G-26 Navahos were to be tested in support the of North American's B-70 bomber and F-108 long-range interceptor programs. But after two unsuccessful launches in late 1958 that project was completely canceled at the insistence of the B-70 Weapons System Project Office.

Technical Description

The booster was designed to take the cruise stage to Mach 2.75 at 13 km altitude, at which point it would cut off. It would separate 1.5 seconds later at 14.6 km altitude, then fall back to earth a short distance downrange from the launch site. The complex conical structure was made primarily of 20-24ST aluminum alloy, heliarc-welded and chem-milled to 3 mm thickness between the weld lands. The liquid oxygen tank was forward, a largely monocoque structure with longerons running aft of the forward cruise stage attachment fitting. It had a capacity of 18,090 kg. Tank pressurization was by gaseous oxygen generated by the inevitable boil-off of the cryogenic liquid; but red fiberglass insulation was applied to the external skin of the booster outside of the liquid oxygen tank to minimize this boil-off. Aft of the oxygen tank was the fuel tank, a semi-monocoque structure that carried most of the loads during ascent. This had a capacity of 12,950 kg of fuel. The liquid oxygen line ran through the middle of the tank, from the oxygen tank above to the engines below. Two small fixed separation fins were attached to the intertank structure to ensure the booster would fly away from the cruise stage once released.

Aft of the fuel tank was the engine bay, with two fixed LR71 engines. Thrust vector control was by V-2-style graphite vanes that were moved into the exhaust. Two large fixed canted fins were attached to the engine bay, providing vehicle stability during ascent. After the decision was made to upgrade the engines from alcohol to kerosene fuel, with a 7% improvement in performance, some detailed design changes had to be made to the design of the fuel tank. This resulted in a delay of final drawing release to June of 1954, and delayed static testing of the modified booster stage to December 1954.

The cruise stage used the same configuration as the turbojet-powered X-10 test vehicle - delta wing, dual engines and vertical stabilizers, forward horizontal control surfaces. Dimensionally it was just 2% larger than the X-10, but differed in detail, reflecting the higher altitude, higher speed, and different type of engines used. The canted twin vertical stabilizers were larger and farther aft. The wings had a notched appearance, with large lobed rudders that extended over the wingtip. An inlet between the vertical stabilizers fed the Auxiliary Power Unit, required since ramjets had no rotating machinery to be used for power generation. From fore to aft the fuselage consisted of a nose compartment; the guidance compartment, which housed the N-6 inertial navigation system and PIX10 autopilot; the forward fuel tank; the instrument compartment, used for test and telemetry equipment in the flight test version but capable of housing a 3150-kg, 2.15-m long W-4 or W-13 nuclear weapon; the main fuel tank; and the aft body compartment, which housed the APU. The cruise stage had a maximum capacity of 24,070 liters of JP-5 kerosene fuel.

The inlets for the engines were substantially larger than the X-10, and used diffuser spikes instead of the X-10's convergent/divergent inlet duct. The fuselage was of predominately aluminum structure, as the X-10, but used titanium in the hotter nose, wing leading engines, and engine exhaust areas. In sustained Mach 2.75 cruise the vehicle would reach temperatures of 270 deg C.

G-26 Navahos would be flown using both a radio-control system and prototypes of the N-6 stellar-inertial system planned for the operational missile. The autopilot and radio-control system and its gyroscopic platform had been proven in tests of the X-10 drone. The XN-6 stellar-inertial navigation system used paired counterrotating gyroscopes to compensate for the precession errors that were seen in the earlier single-gyro-per-axis XN-2 design. It also introduced hydrodynamic bearing gyros in place of the XN-2's air bearings.

Manufacturer: North American. Launches: 11. Failures: 8. Success Rate: 27.00%. First Launch Date: 1956-11-06. Last Launch Date: 1958-11-18. Launch data is: complete. Apogee: 25 km (15 mi). Liftoff Thrust: 1,067.400 kN (239,961 lbf). Total Mass: 71,881 kg (158,470 lb). Core Diameter: 1.76 m (5.77 ft). Total Length: 28.00 m (91.00 ft). Span: 8.72 m (28.60 ft). Standard warhead mass: 3,150 kg (6,940 lb). Maximum range: 4,900 km (3,000 mi). Number Standard Warheads: 1. Standard warhead: W13. Boost Propulsion: Liquid rocket, 2 x Lox/Kerosene. Boost engine: XLR-83-NA-1. Cruise Propulsion: Ramjet. Cruise engine: XRJ47-W-5. Cruise Thrust: 66.700 kN (14,995 lbf). Guidance: Inertial+Stellar/Radio Command. Maximum speed: 3,100 kph (1,900 mph). Ceiling: 24,500 m (80,300 ft). Development Cost $: 679.800 million. in: 1956 average dollars. Total Number Built: 18. Flyaway Unit Cost $: 5.000 million. in: 1959 unit dollars. Cost comments: Development cost through program cancellation for all Navaho versions.

• Stage Number: 1. 1 x Stage: G-26 Navaho Booster. Gross Mass: 42,403 kg (93,482 lb). Empty Mass: 11,337 kg (24,993 lb). Thrust (vac): 1,204.119 kN (270,697 lbf). Isp: 273 sec. Burn time: 76 sec. Isp(sl): 242 sec. Diameter: 1.76 m (5.77 ft). Span: 1.76 m (5.77 ft). Length: 23.26 m (76.31 ft). Propellants: Lox/Alcohol. No Engines: 2. Engine: XLR-83-NA-1. Other designations: XB-64, XSM-64. Status: Out of production. Burns out at altitude 13,000 m, Mach 3

• Stage Number: 2. 1 x Stage: G-26 Navaho Missile. Gross Mass: 29,478 kg (64,987 lb). Empty Mass: 9,977 kg (21,995 lb). Thrust (vac): 66.704 kN (14,996 lbf). Isp: 1,200 sec. Burn time: 6,500 sec. Isp(sl): 0 sec. Diameter: 1.55 m (5.08 ft). Span: 8.71 m (28.57 ft). Length: 20.67 m (67.81 ft). Propellants: Air/Kerosene. No Engines: 2. Engine: XRJ47-W-5. Other designations: XB-64, XSM-64. Status: Out of production. Separates from booster at 14,600 m, Mach 3. Mach 2.75 cruise, 5,600 km range, payload 2500 kg in 2.59 m x 1.50 m compartment.

1946 March 24 - Launch Vehicle: Navaho X-10, Navaho G-26, Navaho G-38, Navaho SSM-A-2.

• MX-770 strategic missile study contract awarded Nation: USA. Program: Navaho. North American received W33-038-ac-1491, a $500,000 letter contract, for study of the MX-770, an 800 km range, supersonic guided missile with a 900 kg nuclear warhead. References: 44.

• MX-770 redirection Nation: USA. Program: Navaho. The concentration on fhe 800-km range missile was to be abandoned. Prototype missiles were now to be produced in three phases. Phase I would produce a missile with a range of 280 to 800 km; Phase II, one of 800 to 2400 km; and Phase III one of 2400 to 8000 km.References: 44.

• US Army Air Corps assigned control of surface-to-surface strategic missiles Nation: USA. Program: Navaho. References: 4460.

• U.S. Army Air Corps becomes U.S. Air Force Nation: USA. Program: Navaho. The Air Force was now a separate service from the US Army. The agreement was made that the Air Force would only handle missiles with ranges over 1600 km. So the range requirement for the MX-770 (later the Navaho) was increased to 1600 km, while carrying a 1350-kg payload with an 800 m CEP, and it became an Air Force missile. The 800-km MX-771 (later Matador) became an Army missile. The MX-775 Snark already had an intercontinental range requirement, and became an Air Force missile.References: 4460.

• USAF wishes to concentrate on longer-range Navaho. Nation: USA. Program: Navaho. The Navaho was redefined by the customer in a revised three-phase program using a rocket booster and ramjet cruise. Track, air, and vertical pad launch were to be studied. The first phase would produce a missile with a range of 1600 km while carrying a 1350 kg warhead. Phase two would produce a missile that could carry a 1350 kg warhead to a 3200 to 4800 km range. Phase 3 would be the intercontinental version, carrying a 4500 kg nuclear warhead to an 8000 km range.References: 221.

• Advanced Navaho concept Nation: USA. Program: Navaho. North American began study of an advanced version of the Navaho, which would use a separate, jettisonable rocket booster. This would allow the cruise stage to be ignited at near-cruise velocity, and to be filled with only ramjet fuel, which would vastly extend the range. In this same month design of the XN-1 inertial navigator is completed.References: 221.

• North American Aerophysics Laboratory moved to Downey. Nation: USA. Program: Navaho. Together with the company's Electromechanical Division, the expanding group was moved into an ex-Consolidated Vultee bomber factory east of Los Angeles. It was here that the Navaho, and later Hound Dog missiles, the Apollo command module, and the Space Shuttle would be built.References: 221.

• Cold War intensifies - US missile programs given higher priority Nation: USA. Program: Navaho. Reacting to Russia's explosion of an atomic bomb, and the Communist victory in China's civil war, the US military begins increasing funding to the low-priority missile development programs begun in 1946. The Martin MX-771 tactical cruise missile is reinstated; additional funds are plowed into the Rascal and Snark programs; and the Corporal tactical missile is modified to carry a nuclear warhead. The Navaho aerodynamic design is frozen so that fabrication of the XSSM-A-2 flight articles can begin.References: 221.

• Navaho reoriented Nation: USA. Program: Navaho. The XSSM-A-2 1600-km range version of the Navaho is canceled. The three airframes completed are abandoned. The USAF instructs North American to proceed instead with development of a 10,200-km range version of the missile using the same aerodynamics, engines, and navigation systems already in development. This is to deliver a 3150-kg nuclear payload, and is to be achieved by making a separable booster stage with two engines deliver a ramjet-only cruise stage to ignition velocity.References: 221.

• Navaho specification finalized. Nation: USA. Program: Navaho. The missile, now designated WS-104A by the USAF, was to deliver a 3150-kg warhead with a CEP of 450 m over a range of 10,200 km while cruising at Mach 3 at over 18 km altitude. The final missile would be developed in a three-phase program: Phase 1, using the reusable X-10 drone, would test the aerodynamics, structural concepts, autopilot, and inertial navigation system for the cruise missile using turbojet engines in an aluminum structure to achieve speeds of up to Mach 2. In Phase 2, the G-26 test vehicle would be a 2/3 scale version of the final version, testing the vertical launch booster, and a steel-structure ramjet-powered cruise vehicle that would reach Mach 2.75 and a range of 2300 km. Phase 3 would fly the G-38, the full-sized prototype for the operational system. The payload was sized to match the 20-kiloton W-4 nuclear warhead, 3150 kg in mass, 1.5 m in diameter and 2.3 m long. References: 221.

• Air-launched Navaho dropped Nation: USA. Program: Navaho. All work on the air-launched versions of Navaho was stopped. North American was to concentrate on rocket-boosted missiles. References: 44.

• Wright gets G-26 ramjet contract Nation: USA. Program: Navaho. The engine was designated XRJ47-W-1. References: 221.

• LR43 run at 430 kN thrust Nation: USA. Program: Navaho. In preparation for development of the 540 kN LR71, the LR43 engine is run for six seconds at 430 kN thrust, compared to its 333 kN rated thrust. Preliminary design of the LR71's new lightweight tubular combustion chamber was begun. These brazed tubes would carry fuel to cool the chamber more evenly than the simpler double-walled German design of the LR43.References: 221.

• G-26 booster preliminary design review. Nation: USA. Program: Navaho. References: 221.

• X-7 tests prototype Navaho ramjet Nation: USA. Program: Navaho. A 20-inch diameter ramjet, a subscale version of the 40-inch engine for the Navaho, first flies on the X-7 rocket. Of the seven launches, only one was completely successful, and two partially successful. References: 221.

• First static firing of LR71 test engine Nation: USA. Program: Navaho. The 540 kN combustion chamber was the most powerful ever tested, but still used the double-walled combustion chamber design of the LR43 rather than the brazed tubular wall construction planned for the production LR71. Build of the first engine to this design would be completed in October.References: 221.

• USAF inspects Navaho G-26 mockup Nation: USA. Program: Navaho. References: 221.

• Navaho engine reaches 445 kN thrust. Nation: USA. Program: Navaho. At Santa Susana, Calif., a complete liquid-rocket engine assembly (Navaho) having a thrust in excess of 100,000 pounds (445 kN) was fired for the first time. References: 17.

• G-26 drawing release Nation: USA. Program: Navaho. The drawings were released to the shop and fabrication of component parts began. References: 221.

• Navaho G-26 contract Nation: USA. Program: Navaho. The USAF released the full-scale development contract for the Navaho G-26, consisting of 10 cruise missiles, 13 boosters, and five N-6 stellar-inertial navigation systems (early flights would be radio-controlled). First delivery was scheduled for 1953 and first launch February 1956.References: 221.

• REAP Program Nation: USA. Program: Navaho. North American's rocket group begins the Rocket Engine Advancement Program, to identify improved rocket technology. One early conclusion was that the performance and logistics could be significantly improved by shifting from alcohol to kerosene fuel, using a new specification RP-1. The decision is made to change the propellants for the Navaho G-38 production version booster. The LR71 engine, modified to burn kerosene, would be designated LR83. This in turn was the basic engine that would power the Thor, Jupiter, Atlas, Saturn I, and Delta rockets into the next century.References: 221.

• Navaho engine reaches 890 kN thrust. Nation: USA. Program: Navaho. At Santa Susana, Calif., a complete liquid-rocket engine assembly (Navaho) having a thrust in excess of 200,000 pounds was fired for the first time. References: 17, 278.

• Navaho G-26 static tests begin Nation: USA. Program: Navaho. Vehicle 3 is placed in a static test fixture at Downey. References: 221.

• Navaho navigation system change Nation: USA. Program: Navaho. The XN-1 inertial system had been replaced by the XN-2 stellar/inertial system in 1951. The XN-2 had been flight tested aboard a C-97 aircraft between April 1952 and May 1953. This is in turn was replaced by the XN-6. The XN-6 introduced paired counterrotating gyroscopes to compensate for the precession errors resulting from the single-gyro-per-axis XN-2 design; and introduced hydrodynamic bearing gyros in place of the XN-2's air bearings. N-6 flight testing began aboard a T-29 in May 1954.References: 221.

• First wind tunnel tests of a full-sized Navaho ramjet engine Nation: USA. Program: Navaho. References: 221.

• Navaho inertial system tested. Nation: USA. Program: Navaho. Inertial guidance system for Navaho X-10 missile tested in first flight at Downey, California aboard North American's T-39 testbed. References: 17.

• Navaho G-26 booster static testing begins Nation: USA. Program: Navaho. References: 221.

• Navaho G-26 second production contract Nation: USA. Program: Navaho. This added 12 more cruise stages, 21 boosters, and 6 N6 navigation systems, bringing the total procured to 22 cruise stages, 34 boosters, and 11 navigation systems. References: 221.

• Navaho G-26 static test article ruptures Nation: USA. Program: Navaho. During simulated propellant loading (with water) at Downey, a crack opened at one of the cruise stage mounting points. The water drained out of the tank, creating a vacuum, followed by implosion of the oxygen tank. References: 221.

• First pair of Navaho ramjets accepted by Air Force Nation: USA. Program: Navaho. References: 221.

• North American reorganizes Nation: USA. Program: Navaho. With the growth of its missile products beyond the Navaho program, and emerging requirements for the Navaho's navigation and rocket engine systems on ballistic missiles, North American broke up the Navaho program into two new divisions. The Missile Development Division, in Downey, would handle the Navaho missile and Hound Dog air-launched cruise missile, a derivative of the X-10 Navaho test vehicle. The Autonetics Division, would handle inertial navigation and other avionics products, and move from Downey to Anaheim. The Rocketdyne division would handle North American's increasing line of liquid rocket motors, and move to a new facility in the western San Fernando Valley in Canoga Park, close to North American's rocket test facilities in the Santa Susanna mountains. References: 221.

• North American proposes Navaho acceleration Nation: USA. Program: Navaho. Facing being surpassed by the fast development of the Atlas ICBM, North American proposes Project Broomstick. This would accelerate Navaho G-26 inertial-navigation-equipped dive-in flights to October 1956. This would make the vehicle expendable, removing all the likely problems in developing a recoverable vehicle that was in any case not applicable to production. Deletion of the landing gear and parachutes would also allow greater range to be demonstrated. Altogether it was believed the change would allow G-38 full-scale vehicle flights to start in June 1958 and deployment of the operational Navaho in 1960.References: 221.

• First Navaho G-26 flight booster delivered to Cape Canaveral Nation: USA. Program: Navaho. References: 221.

• First Navaho G-26 flight cruise stage delivered to Cape Canaveral Nation: USA. Program: Navaho. However continued problems and late delivery of the Auxiliary Power Unit pushed the planned first launch date from May to July. Three APU's were shipped before one was accepted. Attempts for a pad static test of the boost engines began in August. Seven attempts were made through the end of September. The fiberglass liquid oxygen tank insulation delaminated during the first propellant loading; chair springs were used to hold it on in subsequent tests. Helium lines ruptured; the engine was shut off after three seconds due to high gas generator temperatures; the G-26 cruise stage's landing gear deployed internally, cracking the skin; finally at the end of September a 34-second test was completed, but on ground power after the APU failed. The missile was pulled from the flight order and the first Broomstick flight canceled.References: 221.

• Navaho G-26 Flight 1 Nation: USA. Program: Navaho. Agency: USAF. Apogee: 4.00 km (2.40 mi). Continuing problems with APU reliability delayed the launch to November. Various problems extended the countdown from the planned 7 hours 30 minutes to 14 hours 30 minutes. Successful launch, then vehicle pitched up and disintegrated 26 seconds after launch, impacting 4 km down range. It was found the pitch rate gyro had been installed backward.References: 872.

• Navaho - the beginning of the end. Nation: USA. Program: Navaho. With the Navaho stuck on the pad, and the Atlas ICBM nearing first flight, the Air Force began cutting back funds to the Navaho. Advertising for construction of G-38 production missile support facilities at the Cape was pulled, and the program was rescheduled to accommodate a 32% funding cutback in 1958, with construction limited to 16 G-26 missiles and the first G-38 flight delayed from June 1958 to February 1959.

• Navaho launch scrub Nation: USA. Program: Navaho. There were ten attempts to launch Navaho G-26 vehicle number 4 since the first static firing test on 3 December 1956 had been unsuccessful. The vehicle was plagued with problems with the engines and APU, resulting in engine burn-through, engine non-ignition, as well as other unrelated problems - ramjet engine fires, destruct package failures. The vehicle was pulsed from the launch order.References: 221.

• Navaho G-26 Flight 2 Nation: USA. Program: Navaho. Agency: USAF. Apogee: 24 km (14 mi). G-26 number two / booster 6 lifted off after a 9 hour 48 minute countdown with nearly five hours of holds, on the first attempt after two successful static firings. However failure of a launch lanyard meant the kerosene start-pod on the booster remained attached. This sheared off at 4500 m, causing extensive booster damage. Thrust decayed. The cruise stage separated at Mach 1.3 at 28,300 feet, but this was below ramjet ignition speed. However the pilot on the ground was able to assume radio control of the vehicle, and flew it in a glide over the ocean, even demonstrating landing gear deployment before it pancaked into the water.References: 872.

• Navaho G-26 Flight 3 Nation: USA. Program: Navaho. Agency: USAF. Apogee: 0 km ( mi). Vehicle 4 was still not ready for the first Broomstick flight, so vehicle 5 was substituted. It took five attempts before a 15.6 second static test cleared the booster for launch on 29 March. 8 hours and 42 minutes of hold stretched the five-hour countdown out into the evening. The booster ignited, rose 1.3 m, then shut down. The vehicle fell back onto the pad, exploding. Cause was a 15-second timer that was supposed to shut the engines down 15 seconds after the vehicle hold-downs released if a lanyard had not been pulled free of the vehicle as it rose off the ground. The 15 seconds had been reached before the lanyard pulled free, but by then the vehicle had risen off the pad. This made 15 attempts to launch a Navaho, with only two booster ignitions, both resulting in loss of the vehicle. The Northrop crews at the Cape dubbed their competitor the "Never-Go Navaho" to counter jibes directed at them about the "Snark-infested waters" off the launch area. The Air Force was not amused, and had a tiger-team review of the G-26 on a system-basis which recommended several procedures. Meanwhile G-38 launch plans were further delayed over internal USAF wrangles over launch facility construction.References: 872.

• Navaho G-26 Flight 4 Nation: USA. Program: Navaho. Agency: USAF. Apogee: 12 km (7 mi). The missile launched from the repaired LC-9 on the third attempt. At T+42 seconds, Mach 1.63, and 7,000 m altitude, a fire occurred in the engine compartment after a failure of a regenerative cooling valve to the gas generator. The turbopump shut down, and one engine went out. Nevertheless the vehicle continued, first on one engine, then coasting, to 12,000 m altitude, and the booster separated successfully. But the cruise stage was below ramjet ignition velocity. Again ground control could bring the cruise stage under control as a glider, flying it to an impact 87 km downrangeReferences: 872.

• USAF cancels the Navaho program. Nation: USA. Program: Navaho. The supersonic intercontinental cruise missile had been made obsolete by the Atlas ICBM. 4,705 employees were laid off the day the termination notice was received via an announcement over the public address system to "stop what you are doing, proceed to the nearest exit, and deposit your badge in the bin indicated". By the end of the month the total laid off at North American alone amounted to 15 ,600 employees. However engineering staff was kept on to launch the five completed G-26 missiles, at a total cost of $4.9 million.

  At the time the program was cancelled full-range G-38 missiles were in fabrication with first flight test planned by the end of 1958. The engines, missile frame manufacturing techniques, inertial and stellar navigation equipment, and telemetry/guidance techniques developed for Navaho established the technical basis for many subsequent US rocket developments.References: 221.

• Navaho G-26 Flight 5 Nation: USA. Program: Navaho. Agency: USAF. Apogee: 25 km (15 mi). After a 15 hour 18 minute countdown G-26 number four finally left the pad. The boost phase was completed successfully; but then a guidance system malfunction prevented the cruise stage from separating from the booster until an altitude of 25 km was reached. However the autopilot successfully overcome drastic pitch oscillations created by the lofted trajectory, and the ramjets were successfully ignited. The stage cruised at Mach 2.93 for 280 km. However then the vehicle began drifting off course. The ground pilot banked, but the fuselage screened the airflow to the left ramjet intake, resulting in that engine flaming out. The vehicle lost speed and altitude, and the right engine flamed out a minute later. The missile was ordered into a terminal dive, impacting 425 km downrange.References: 872.

• Navaho G-26 Flight 6 Nation: USA. Program: Navaho. Agency: USAF. Apogee: 24 km (14 mi). The booster worked well, the cruise stage separated at 23.5 km altitude. The ramjets ignited, and the cruise stage accelerated to Mach 3.5. After 15 minutes, the missile began drifting off-course, and ground control took over and banked the missile. One of the ramjets flamed out, and the missile was commanded into a terminal dive and impacted 930 km downrange.References: 872.

• Navaho G-26 Flight 7 Nation: USA. Program: Navaho. Agency: USAF. Apogee: 21 km (13 mi). The booster functioned well, and the cruise stage separated at 20.4 km altitude and Mach 3.24. The ramjets ignited, but before the ground knew that, the telemetry dropped out completely due to a faulty voltage regulator on the missile. Range safety ordered the missile's self destruction at T+75 seconds.References: 872.

• Navaho G-26 Flight 8 Nation: USA. Program: Navaho. Agency: USAF. Apogee: 22 km (13 mi). The booster functioned well, the cruise stage separated at 22 km and Mach 3.15. The ramjets ignited and the cruise stage flew at a sustained speed of Mach 2.8 for forty minutes over a distance of 2000 km. Then the vehicle began a turn for the return to the Cape for recovery. However it seemed the turn was not fast enough; ground control took over, and yet again the right ramjet flamed out in a ground-piloted bank. The missile was commanded into a terminal dive at sea.References: 872.

• Navaho G-26 Flight 9 Nation: USA. Program: Navaho. Agency: USAF. Apogee: 10 km (6 mi). The booster shut down at T+20 seconds in the flight. The vehicle was self-destructed by range safety before separation of the cruise stage had occurred. References: 872.

• Navaho G-26 Flight 10 RISE-1 Nation: USA. Program: Navaho. Agency: USAF. Apogee: 21 km (13 mi). North American had received funding to fly seven surplus G-26 missiles in a program dubbed RISE (Research Into Supersonic Environment), ostensibly to obtain real-world data on Mach 3 flight for the F-108 interceptor and B-70 bomber that they were developing for the USAF. On this first attempt, the booster performed well, but after separation the cruise stage fuel system failed, and ramjet ignition never occurred. The cruise stage impacted 150 km downrange.References: 872.

• Navaho G-26 Flight 11 RISE-2 Nation: USA. Program: Navaho. Agency: USAF. Apogee: 23 km (14 mi). The vehicle disintegrated at 23.5 km altitude at the time of booster shutdown and cruse stage separation. The USAF canceled further RISE flights and this definitively marked the end of the Navaho. References: 872.

• Navaho program closed out. Nation: USA. Program: Navaho. One G-26 missile delivered to Cape Canaveral but not launched was retained there for the open-air missile park. X-10 s/n 1 was displayed in the Air Force Museum in Dayton. Harrison Storms attempted to sell the USAF on using the completed work for space launches. One proposal was to use the boosters as the first stage of a satellite launcher with Able upper stages. Another was to cluster four of them together and launch an X-15 manned rocketplane into orbit. Nothing came of these proposals. Four completed G-26 missiles and the under-construction G-38 missiles were scrapped.

• McDowell, Jonathan, Jonathan's Space Home Page, Harvard University, 1997-present. Jonathan McDowell's complete on-line listing of all objects orbited and over 20,000 rocket launches Accessed at: http://www.planet4589.org/jsr.html.

• Gibson, James N, The Navaho Missile Project, Schiffer, 1996. ISBN: 0764300482. The only book available on the fabulous Navaho project. Written by the son of one of the project workers, not nearly detailed enough, but it's all we've got.... More at amazon.com...

• Nicholas, Ted G., U.S. Missile Data Book, 1983, Seventh Edition, Data Search Associates, Fountain Valley, California, 1982..

• Parsch, Andreas, DesignationSystems.Net, . Outstanding, unique reference for aircraft, missiles, propulsion, and avionics systems. Accessed at: http://www.designation-systems.net/.