shock absorbers, there are significant differences which greatly affect vehicle ride and performance. The XM-1 uses 14 bars compared to the 12 bars on M60 and the XM-1 is longer. These features reduce the pitching and bouncing in the XM-1 tank. The XM-1 bar is also longer and allows improved wheel travel for faster and smoother cross-country operations.

In addition, the XM-1 rotary shock absorbers are larger and more efficient than those in the M-60 advanced torsion bar system. XM-1 with 1500 horsepower and ATB for cross-country operation achieves 35 to 40 mph, compared to the 10 to 16 mph performance of the M-60 tank equipped with ATB. Based on demonstrated performance, M-60 ATB suspension should not be equated with the XM-1 ATB suspension. The comments made by the test crew members were related to the M-60A1 ATB, not the XM-1 ATB.

Finally, ride quality testing conducted at APG and Ft. Knox did verify that the hydropneumatic suspension (HSS) provides an improved ride over the ATB suspension, a combined HSS/ATB suspension and the standard torsion bar (STB) suspension. Although the hydropneumatic suspension improved the ride quality of the M-60 tank, the average increase in cross-country speed was only 2 to 4 mph better than the ATB and STB equipped tanks. Furthermore, the maximum potential for the HSS equipped tank over cross-country terrain is limited to 18 to 20 mph. However, the test also showed that the cross-country speed was only speed achieved by the M-60 in terrain similar to that found in Europe is limited to about 11 mph with the standard suspension and about 13 mph with the HSS due to the limited power of the tank's engine. For these reasons, the increase in effectiveness of the HSS tank is considered only slightly better than the ATB and STB M-60 tanks even though the crew ride was improved.

Senator THURMOND. The Army has stressed the "shoot on the move" capability. Now it can be added to the M-60 and improved on the XM-1. What would be the cost in both instances, reducing the cost of the current suspension systems to get the difference between those and the hydropneumatic?

Colonel BUTLER. Before addressing cost data, it should be noted that the addition of the HSS system would provide an additional improvement in the M-60's shoot-on-the-move capability only under certain conditions. For example, over cross-country terrain at a speed of 12 mph, the M-60 achieved the same round hit performance when equipped with the standard or HSS ssytem. At 18 mph, the HSS equipped M-60 achieved reasonable first round hits while the standard M60 could not travel at this speed. However, the test also showed that the crosscountry speed achieved by the M-60 in terrain similar to that found in Europe is limited to about 11 mph with the standard suspension and 13 mph with the HSS due to the limited power of the tank's engine. Because of this marginal improvement, the decision was made not to adopt the HSS for the M-60 fleet. It would take about forty months to get the HSS into production. By that time, new production of the M-60-A-3 will be virtually completed. Therefore, we would have to retrofit the HSS to the M-60 fleet during depot overhaul. The unit hardware cost of the HSS for this retrofit was estimated at the time of the analysis to be $31,770 in fiscal year 1977 dollars. Application cost was estimated to be $6,419 per tank. The procurement cost was based on 7,900 units and would be significantly greater if we procured only enough to equip the M-60-A-3 fleet in the early 1980's.

The XM-1 system meets or exceeds all requirements for firing on the move with its high hardness torsion bar system. The Army sees no requirement to modify the suspension system. The cost impact of incorporating full hydropneumatic suspension on the XM-1 versus present high hardness torsion bar is estimated to be approximately $22 thousand per vehicle in production plus $10 million for development and testing.

Senator THURMOND. We have the laser range finder and the computer on the M-60-A-3's to give us more accuracy and effectiveness. Would these investments not be greatly enhanced with a suspension system that gives us a real shoot on the move capability for the M-60?

Dr. PIERRE. The laser provides a significant improvement in the ability of the M-60-A-3 crew to range while moving at speeds up to about 10-12 mph over the M-60-A-1 which has stabilization but no laser. Since the power of the engine limits the tank's normal cross-country speed to about 10-12 mph, there would be only a marginal increase in effectiveness by equipping the M-60-A-3 with the HSS. This is confirmed by the March 1978 report of the Operational Feasibility Test of M-60 Improved Suspension systems which concluded that "Tanks

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equipped with the hydropneumatic, hybrid, or advanced torsion bar suspension systems did not show a significant improvement in overall gunnery performance when compared to tanks equipped with the standard suspension system."

Senator THURMOND. Mr. Secretary, what additional kill capability would you get on the M-60 with the new suspension system?

Dr. PIERRE. The standard and HSS equipped M-60-A-3 have essentially the same main gun hit probabilities at the 10-12 mph cross-country speed which we can achieve with the power of the current tank engine. When the terrain permits the tank to achieve higher speeds, testing shows that the HSS would permit the M-60-A-3 to achieve reasonable first round hit probabilities at 18 mph. Using these data in the Tank Exchange Model, the relative kill capability of the HSS equipped M-60-A-3 ranges between being a little less effective than the standard M-60-A-3 to about 11⁄2 times better, depending upon the terrain, speed and other model parameters.

Senator THURMOND. Is it not true that this new system would greatly enhance the survivability of the M-60 by enabling the tank to move faster?

Dr. PIERRE. Tank survivability can be increased by improved firepower, protection or mobility. The hydropneumatic suspension system permits the M-60 tank to achieve improved mobility when the tank is not power limited. Testing shows, however, that on cross-country terrain similar to that found in Europe. power of the M-60-A-3 limits its top speed to about 13 mph, which is only 2 mph faster than the M-60-A-3 equipped with standard suspension. This modest increase does not significantly improve the tank's survivability.

Senator THURMOND. Also, if this system were added would not the fatigue factor on the crew be greatly reduced?

Dr. PIERRE. Yes, comparison testing of HSS equipped and standard M-60 tanks shows that the HSS provides a better ride at the same speed, and hence, causes less crew fatigue.

Senator THURMOND. Mr. Secretary, considering our needs in NATO and the fact we will have the M-60's for some time, I feel the Army should carefully consider this system for the M-60. Can you assure me this will be done and advise this Committee of your findings.

Dr. PIERRE. Senator, I can assure you that this has already been done. General Lawrence's and my reports to this Committee today on the Tank Readiness Initiatives address that point.

The Army has been evaluating the HSS and other improved suspensions for comparison purposes since 1975. In arriving at the objective of more XM-1's faster, M-60 product improvement initiatives were severely curtailed. Within the context of this total tank program, we rank ordered M-60 product improvements from a requirements, performance and cost standpoint.

Hydropneumatic suspension on the M-60 was addressed in this process, In the end, HSS system was not shown to be one on which we could justify continued expenditures.

Senator THURMOND. I would also like to know the total program cost of the 120 mm gun as again the cost of putting the hydropneumatic system on the XM-1.

General BABERS. The total program cost of the 120mm gun system is dependent upon the options selected for development, investigation and production of the 120mm gun XM1 tank. This program is scheduled for a special ASARC review on 17 April after which the program will be finalized. I would prefer, therefore. to provide the total program cost estimate after the final program is determined. The estimated cost of incorporating a full hydropneumatic suspension system on the XM1 is approximately $10 million for RDT&E and $22,000 per vehicle for a total of $165 million based on 7058 tanks.

Senator THURMOND. Will not the weight of the 120mm gun increase the need for a better suspension system for the XM-1 to assure its shoot on the move capability?

General BABERS. No. The suspension system on the XM1 tank is designed for a gross vehicle weight of up to 62 tons. The 120 mm gun XM1 tank is estimated to weigh about 60 tons.

Senator THURMOND. The Fort Knox report states as a conclusion, that the Cost and Operational Effectiveness Analysis "supports procurement of an improved suspension system." Yet in the material supplied recently by the Army, it was stated that this Analysis only showed the hydropneumatic suspension system "marginally cost effective." Would you explain these apparent inconsistent statements?

General KEITH. Let me explain it this way Senator. The report to which you refer states that, as with many systems, the 15 year operating and support costs overwhelm any differences in procurement or any other cost. This results in negligible difference between the costs of the candidates and makes the analysis one of equal cost with variable effectiveness. If you are willing to accept the high acquisition cost, the small increase in effectiveness, which we have provided some details of, would support acquisition of an improved suspension system. But, as we have also described, we are interested in the near term value of the M60A3 and view it in that context. Thus the $140 million procurement cost was judged too great for the small and short term effectiveness increase it would give to our tank fleet.

Senator CULVER. I want to thank all of you for your appearance and testimony today. It has been a long afternoon, especially on a Friday.

Mr. PIERRE. Thank you, Mr. Chairman.

Senator CULVER. The committee will stand in recess until further call of the Chair.

[Whereupon, at 5:25 p.m., the subcommittee was adjourned, subject to call of the Chair.]

DEPARTMENT OF DEFENSE AUTHORIZATION FOR APPROPRIATIONS FOR FISCAL YEAR 1979

WEDNESDAY, APRIL 19, 1978

U.S. SENATE,

SUBCOMMITTEE ON RESEARCH AND DEVELOPMENT
OF THE COMMMITTEE ON ARMED SERVICES,

Washington, D.C.

FLIGHT SIMULATORS AND RELATED DEVICES

The subcommittee met at 9 a.m., pursuant to notice, in room 224, Russell Building, Senator Barry Goldwater presiding.

Present: Senators Goldwater and Bartlett.

Also present: Robert Q. Old, professional staff member and Kaylene Green, assistant.

Also present: Ron Lehman, assistant to Senator Bartlett.

OPENING STATEMENT BY SENATOR BARRY GOLDWATER

Senator GOLDWATER. The meeting will come to order.

Today we hear from the Department of Defense on the fiscal year 1979 request for research and development funds and procurement funds for flight simulators and related devices. The total authorization request for this category is $36.4 million for research and development and $295.6 million for procurement.

By way of comparison, the amounts funded last year were $45.6 million for research and development and $217 million for procurement. Said another way, this year's request is up about $69 million over last year, primarily because of the beginning of some new aircraft simulator programs.

As I stated, this hearing will cover both the fiscal year 1979 research and development request and the procurement request for flight simulators. Normally, this committee deals only with research and development, whereas the Subcommittee on General Procurement would consider the procurement portion of the request.

However, the precedent for considering both was established 2 years ago when I chaired the first hearing on flight simulator programs.

A lot of progress has been made since that hearing and many systems are now in production and beginning to come into the service inventories. We will want to see how these programs are progressing.

Also, much data has been accumulated on the effectiveness of these devices and the committee will be interested in hearing from the witnesses on this aspect of flight simulators.

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