III. HIBEX - UPSTAGE

A. BRIEF OVERVIEW

HIBEX (High Booster Experiment) was a 2-year research project to investigate the technology of a very high acceleration, short range anti-ballistic missile interceptor, for hard point: defense. The HIBEX missile achieved nearly 400 g peak axiai and over 60 g lateral acceleration, reaching a velocity of nearly Ma = 8, in a little over 1-sec burn time, with pitch over from a vertical ejection from a silo to a trajectory of 15 deg elevation. In 2 more years, UPSTAGE, a maneuvering HIBEX second stage, demonstrated over 300 g lateral acceleration and a side-force specific impulse Isp > 1000 sec using external burning, jet flow control techniques and a laser gyro for guidance. The HIBEX technology furnished the basis for the Army's LoADS short range interceptor program. UPSTAGE jet maneuvering control technology has been incorporated into the SDI's HEDI missile.

B. TECHNICAL HISTORY

A number of early U.S. studies of Ballistic Missile Defense (BMD) indicated that the problem of active defense of restricted-area "hard points" appeared much more tractable than that of defending larger urban areas, the primary emphasis of the Army's NIKE ZEUS BMD project A presidential decision in late 1962 led to the cancellation of NIKE ZEUS and the start of the NIKE X R&D program which involved development of hardened phased-array radars capable of computer-controlled acquisition and tracking of a large number of reentry objects, and a two-stage high acceleration missile, SPRINT, which was to intercept and kill reentry vehicles (RVs) by an explosion of its nuclear warhead at altitudes of about 45,000 ft SPRINT was launched after "atmospheric filtering" had allowed better discrimination of the threat RV from decoys.1

About the time of this Presidential decision, there were also further studies of alternatives to NIKE X, involving a variety of radar and missile systems, with a view to possible future hard point defense.2 Hardpoint BMD appeared to be easier than urban defense for a number of reasons. The defended target is "harder," and the stakes were lower than urban defense. Technically, the radar ranges could be shorter, search could be confined to a narrow "threat corridor," and atmospheric filtering simplified the problem of sorting out the real threat RVs. However, the time for intercept action was compressed into a narrow "window" (see Fig. 3-1) requiring a very high acceleration missile. Also, the hardened large phased array antennas being constructed by BTL for NIKE X were expensive, and economic hard point defense required that such antennas have lower cost

Shortly after the NIKE X decision, ARPA's project DEFENDER commenced investigation of several key advanced concepts for hard point defense, including a high acceleration missile in its HIBEX project, together with the HAPDAR (Hard Point Demonstration Array Radar), a low cost hardened phased array radar.3 Previously, ARPA had investigated other advanced BMD concepts but had not, to this point, undertaken any booster development under DEFENDER. Its earlier CENTAUR and SATURN projects had aimed at space flight and in both cases, after early funding critical to getting them started and some brief technical involvement by ARPA, the major part of the technical development of these vehicles was done by other agencies.3 In the case of HIBEX, in contrast, ARPA was in close control throughout.6

Besides exploring the technical boundaries of high acceleration missiles and the associated control problems, ARPA's interest at the time also encompassed the possibilities of non-nuclear kill of RVs, and the feasibility of firing a second interceptor if the first one failed.7 While the possibilities of using HIBEX alone for intercept were considered, the ARPA concept also included a second stage which might be able to execute the "high g" maneuvers required to "chase" maneuverable RVs, then beginning to be studied.8

At the time of these investigations it was known that propellant wakes could absorb and refract electromagnetic waves. Therefore, the ARPA concept envisioned command guidance from the ground during a "coast" phase of HIBEX flight, after propellant burnout. In the actual HIBEX experiments, however, no attempt was made to do any external guidance. Internal, closed-loop guidance was used.

Preliminary studies of HIBEX indicated (see Fig. 3-2) that accelerations of several hundred g's and burnout velocities of about Mach 8 would be required. HIBEX was to be launched vertically, from a small silo, and afterwards would "pitch over" to a direction suitable to accomplish intercept, requiring high "g" also transverse to its axis (Fig. 3-3).

It did not seem possible, based on information from the initial HIBEX studies, to be able to use a scaled vehicle for tests in the usual scheme of engineering research.



Figure 3-1. Hard Point System "Window" Profile4



Figure 3-2. Effort of Commitment Altitude on Interceptor Characteristics (From Kupelian, op. cit.)



Figure 3-3. HIBEX Experiment Mechanization (from Kupelian, op. cit., p. 387)

Therefore it was decided early-on, to undertake HIBEX as a series of full scale field tests. This was more risky, but if successful the results could be more convincing. The performance desired was higher than SPRINT'S first stage (although the two-stage SPRINT achieved a higher terminal velocity and a longer flight); also HIBEX would be a much smaller vehicle. As a research program, the boundaries of performance to failure could be explored in HIBEX without the constraints of practicality imposed in engineering a system for production. In contrast, because a near-term production was expected, SPRINT had these kinds of constraints.

In particular HIBEX required a higher burning rate propellant than was available, and one which could stand several hundred "g's" without undue deformation or fracture. Technology was available to increase the burning rate by addition of small metal fragments, and also for strengthening the propellant "matrix," but tradeoffs were required. Measurement techniques had not been developed for such important quantities as propellant strain in the regime of stress expected. Consequently, a series of static firings was made to test successive approximations to eligible propellants.

At the time of HIBEX, aerodynamic characteristics of vehicles in hypersonic flight with large angles of attack were not well known. Wind tunnel tests were performed to assist in gaining understanding of the forces and moments; but the stability of the actual system was somewhat a matter of guesswork, with fortunately compensating errors made in design parameters.9

An outline of early HIBEX requirements is shown in Figure 3-4. Boeing was chosen as prime contractor, with Hercules for propellant development. A large number of measurements were planned for each flight, in accordance with the exploratory nature of the investigation. Besides being in entirely new parameter ranges, the measurement instruments themselves had to withstand very severe environments. The HIBEX flights took place at White Sands Missile Range (WSMR) and took advantage of the telemetry and optical range instruments there. Figure 3-5 shows a cut-through diagram of HIBEX. Strap-down mechanical gyros, the only technology then available, was used for guidance in both stages. The first flight was a test of the booster and did not involve on-board flight guidance. The second and later flights incorporated on-board control and involved tests of thrust vector control in one, and later in two dimensions. Thrust vector control was achieved by injection of liquid Freon, as with SPRINT. The final flights involved maneuvers of 75 deg in pitch and 45 deg in azimuth. In the last (7th) successful flight a second stage incorporated a propellant which was burned externally in order to achieve very high transverse impulse.

Figure 3-4. HIBEX Requirements10

• Experiment - Full Scale

• Vertical Silo

• 300 lb Second Stage (15 in. x 15 in.)

• Burnout Velocity 8000 FPS in 1 second

• Elevation 15° to Vertical (Controllable)

Azimuth ±45° (Controllable)

• 0.5 Second: Available for PreLaunch Commands

• Program not to exceed 2 years

• Right and Ground Instrumentation

• Existing WSMR Facilities

• Data and Test Reports

The original 2-year schedule for HIBEX slipped by 2-months, but six out of seven flights were successful. An explosion at one of the propellant testing facilities required reimbursement11 Such explosions of advanced propellants were not unusual.



Figure 3-5. HlBEX Test Vehicle Configuration & Performance (from Moore and Jacobs, op. cit.)

In its flight test HIBEX reached an axial acceleration of about 362 g's, and about 60 g's lateral acceleration. The project results indicated that even higher accelerations were possible.12 The last two flights originated from silos. Measurements were made also of acoustic over-pressures in the vicinity.

Table 3-1 shows a comparison of HIBEX parameter objectives and achievements. Despite the 2-month extension of schedule, the project was accomplished at low cost with five fewer "shots" then originally contemplated.13

Table 3-1. HIBEX Flight Performance* Item Objective Achieved Boost Burn Time 1.05 Sec. 1.124 Burnout Velocity 8,000 fps 8,408 fps Weight of Second Stage 300 lb 295-303 lb Trajectories with Programmed Turns From Vertical To: Elevation 15 deg. 15 deg Azimuth ±45 deg. 45-deg. Burnout Velocity Vector Error ± 5 deg 1.8 deg. maximum Stage Separation Favorable for Missile Guidance Favorable for Missile Guidance**S *Source: Moore and Jacobs, op. cit., p. 22.

A HIBEX symposium was held in 1966, to present its results, and several (classified) articles were published later in the Journal of Defense Research.14

Toward the end of HIBEX, some external burning propellant experiments were conducted with encouraging results. A study was then made of a maneuvering second stage interceptor, UPSTAGE, which would incorporate external burning for sidewise thrust.15 PRESTAGE, the immediate follow-on project to HIBEX, was carried out in the 1965-68 time frame, to investigate external burning in a controlled hypersonic flow environment and the corresponding problems of thrust control, axial and lateral.16 "Disposable" vanes were studied along with lateral jets for thrust vector control. PRESTAGE was carried out by McDonnell-Douglas,17 and included laboratory and flight test experiments, using available rocket motors.

After PRESTAGE, project UPSTAGE began in 1968, dedicated to investigation of a second stage for intercepting maneuvering RVs. A HIBEX vehicle was used for UPSTAGE's first stage. The UPSTAGE effort covered second stage separation phenomena, control system, thrust vector control generation techniques and mechanisms, guidance, aerodynamics, structure and communications. The UPSTAGE vehicle was designed with "lifting" aerodynamic characteristics. An important new guidance feature incorporated was a laser optical gyro, which required no "spin-up," and which had been developed partly with ARPA funding.18

External guidance for UPSTAGE was provided by a command guidance link and tracking by the ZEUS target-tracking radar at WSMR. "Finlet" injections were used to provide transverse thrust. UPSTAGE reached several hundred lateral g's with response times of milliseconds. The UPSTAGE maneuvers were controlled in a simulated MARV chase but no actual interceptions were attempted.19 The tests were generally successful and indicated the feasibility of the technology along with a need to better understand external burning.

In another follow-on project Radar Homing On-Board Guided Intercept (RHOGI) was investigated.20

In 1975 a Presidential decision was made to deploy SAFEGUARD, an advanced version of NIKE X, to defend Minuteman missiles, then not considered a "hardened" system. SAFEGUARD involved SPRINT missiles in silos. After Congress voted to keep U.S. BMD in an R&D status, the Army's subsequent HARDSITE and LoADS programs involved a missile similar to HIBEX in general descriptions of weight and size.21 V. Kupelian, ARPA's HIBEX project manager, was for a time in the Army's ABMDA, in charge of missile-related work in terminal BMD. So far, LoADS has been formally cancelled, but the Army apparently considers its technology to be "on the shelf."

The SDI R&D program for wide area defense does not involve a short range terminal defense missile. However, SDI includes HEDI (High Endoatmospheric Defense Interceptor), a missile incorporating UPSTAGE jet maneuvering control in endo atmospheric intercept, but at somewhat higher altitudes than HIBEX's range.22

C. OBSERVATIONS ON SUCCESS

HIBEX and UPSTAGE were key projects in ARPA's DEFENDER program for hard point defense. In accord with the DEFENDER assignment, these projects explored the boundaries of possible performance of high acceleration missiles for intercept of RVs. HIBEX was widely recognized to have been an impressive R&D achievement. While HIBEX is often compared with the SPRINT system then being built under the Army's BMD program, it must be recognized that SPRINT had the major constraints of a system being engineered for production deployment on a limited time schedule.

UPSTAGE also had a very ambitious objective of demonstrating a capability for chasing MaRV's, a mission not emphasized in the SPRINT system design, and possibly coming close enough for non-nuclear kill. UPSTAGE was successful in demonstrating much of what might be achieved with external burning, but some questions were left for further R&D.23

Through personnel and information, the HIBEX/UPSTAGE technology as well as other aspects of the ARPA hard point defense program seems to have been effectively transferred to the Army. Treaty restrictions have allowed only R&D on the HARDSITE and LoADS concepts. The Army did build and test a hardened phased array radar, and the success of HIBEX is indicated by the fact that the LoADS interceptor missile has not had a development program, but is described as having gross characteristics similar to HIBEX24 and is regarded as "off the shelf," readily available technology. The ARPA-developed laser inertial guidance system is regarded as readily available also. SDI does not include a missile like that in LoADS probably because SDI is aimed primarily at area, rather than terminal defense. SDI's HEDI missile for high endoatmospheric intercept however, does incorporate UPSTAGE jet maneuvering technology.

From project records ARPA outlay for HIBEX appears to have been about $25 million and for UPSTAGE (including PRESTAGE) about $26 million.

Notes

1 ABM project history. Bell Telephone Laboratory, Oct. 1975, p. 1-33, ff.

2 Eg.. Intercept X. conducted by IDA.

3 AO 510 of 9/S3, HIBEX, and AO 516 of 10/63. HAPDAR.

4 From "Introduction for HIBEX." by V. Kupelian, Bulletin of the 20th Interagency Solid Propulsion Meeting, July 1964. Vol III, p. 338 (declassified).

5 CENTAUR and SATURN are discussed in Chapters IV and V of Volume I.

6 Discussion with V. Kupelian, 12/87.

7 Discussion with A. Rubenstein, 11/87.

8 A. Rubenstein and V. Kupelian, ibid. One such MaRV was ARPA's MARCAS. AO 569 of 4/64.

9 Discussion with V. Kupelian, 12/87.

10 From "HIBEX Booster Development" by E.V. Moore and A.M. Jacobs, Bulletin of the 20th Interagency Solid Propulsion Meeting, July 1964, Vol IV, p. 39, (DECLASSIFIED).

11 AO 93 of 5/66, HIBEX Explosion Payment $ 0.5 million.

12 HIBEX Final Technical Report, Boeing, March 5,1966 (DECLASSIFIED), p. 22.

13 Boeing, ibid., p. 396.

14 "HIBEX," an experiment in high acceleration boost for BMD, by CR. Smith, Journal of Defense Research, Vol. 2A, 1970, p. 170 (CLASSIFIED).

15 AO 595 of 7/64, UPSTAGE

16 AO 765 of 8/65, PRESTAGE.

17 Douglas had also been the NIKE ZEUS SPRINT contractor.

18 AO 744 of 6/65.

19 V. Kupelian, ibid.

20 AO 873 of 3/66.

21 Thomas M. Perdue, et al., "Low Altitude Defense for MX (U)," Journal of Defense Research, 82-3, 1982.

22 AIAA Assessment of Strategic Defense Initiative Technologies, March IS, 1982, p. 32.

23 Project UPSTAGE. Progress Report, May 1968, McDonnell Douglas Company (CLASSIFIED). See also "Interaction Control Techniques for Advanced BMD Interceptors," by D.F. Hopkins, et. al.. Journal of Defense Research, Vol. 9,1979, p. 274.