Why Arleigh Burkes Handle Differently
Captain Kenyon Hiser, U.S. Navy
Commander Terry Mosher's professional note, "A New Twist for Arleigh Burkes," in the September 2003 Proceedings (pp. 84-85) highlighted again that handling this class of destroyer is different from handling previous gas turbine-propelled cruisers and destroyers. While it may appear that the performance characteristics of the DDG-51 class should be similar to the other twin shaft, controllable-pitch propeller, gas turbine ships, there are significant differences beyond their length and hull form. Although commanding officers (COs) have learned how to maneuver the Arleigh Burkes, an examination of the cause and effect of these differences may be useful in developing future ship control systems.
Two major drivers and some contributing factors led to different handling characteristics:
* The DDG-51 class was optimized for antisubmarine warfare (ASW) by improving the Spruance (DD-963)-class destroyer design.
* Control system specifications precluded using any feedback (for example, shaft revolutions per minute [RPMJ) to keep the propulsion plant within safe operational limits.
* The officers involved directly in determining the design of the control system had fleet experience primarily with steam-powered-not gas turbine-ships.
* Other factors (not examined here) included the difference in hull form, propulsion plant arrangement, and available shaft horsepower.
Design Problems and Solutions
The principal design driver for ASW is to keep the ship quiet by reducing the own-ship radiated noise that masks the submarine signature or enables the sub to detect the ship. The DD-963 design maintains a minimum of 55 shaft RPM. Ship control at this RPM is provided by adjusting propeller pitch. But a propeller operating off design pitch generates a significant amount of additional noise, which was confirmed dramatically in the early DDG-51 trials, when two view ports were installed above the port propeller. In those clear Caribbean waters, cavitation could be confirmed visually the instant the propeller pitch decreased below 100%. In addition, when the DDG-963s reached 100% pitch, they had reached higher speed, thereby increasing hull flow noise and requiring an increase in masker air flow. This design did not provide optimum slow speed and quiet ASW performance.
The solution for the DDG-51 was to keep the gas turbine at idle until the propellers reached 100% pitch. This produces a much-slower quiet speed than the DDG-963 design-however, it has several unintended consequences for ship control. First, as the turbines remain at idle, there is less immediate power to effect a change in ordered speed at these low power settings. second, because the turbines remain at idle until 100% pitch, shaft speed decreases from a stop bell to the 100% pitch setting. This is confusing because a sailor might focus only on RPM while setting the throttles in response to an order, thus resulting in the wrong speed. Next, there is different idle power available in the split plant (single turbine online per shaft) and full power (dual turbine per shaft) modes. Performance is different depending on the plant mode. The ship reaches 100% pitch at one speed in split plant and at a different speed in full power. Finally, some pitch settings are not obtainable, especially in split plant mode where pitch rapidly increases to 100% with minor throttle adjustments. While this has no operational effect (the difference between 85% and 86% is negligible), it adds to the potential confusion factor. (See Commander Mosher's sidebar in "A New Twist for Arleigh Burkes" for additional details on DDG-51 throttle modes.)
The DDG-51 ship specifications required that the control system not rely on feedback to keep the plant within safe operational limits. This was interpreted by the design team to imply that shaft RPM feedback could not be used to control shaft RPM. Thus, the control system implemented a purely predictive algorithm to control the gas turbine throttle and propeller pitch settings. The primary inputs to this were current and historical throttle position, outside temperature, and number of engines on line. (There was a long-term control loop, but it acted slowly and had minimal authority.) This decision was made despite the fact that each shaft had six independent, redundant methods for measuring shaft speed to keep the plant within limits (two tachometers on the reduction gear and two power turbine speed pickups per gas turbine).
Reportedly, the contractor's designer repeatedly told the program office this design was unsatisfactory. And, as predicted, it was arbitrary and unpredictable. The conning officer had no idea what would happen when he gave a throttle order, except that it probably would not be the same response as the previous one. Worst case was a high-speed ahead bell to back 1/3rd. This action produced consistently hilarious results-unless you were the conning officer in a critical situation or the engineering officer who had to explain the resulting performance to the CO.
As we came to understand the problems with the throttle control, the battle group commander eventually decided immediate action was required. He tied the Arleigh Burke to the pier until the program office provided a new throttle control system. The interim solution was to implement the Spruance-style system, with a fixed 55 shaft RPM minimum speed. My memory is that the "bells mode" pushbutton was converted to a 55 RPM or "shaft idle" mode button. While we debated keeping the shaft idle mode instead of the bells mode for maneuvering, the submarine was still quite a threat. There was concern that a ship would prefer this mode even for ASW operations, which precluded quiet, slow speed performance. After a series of data-collection trials, the control system was modified to include RPM feedback to control shaft speed and to increase throttle authority; gas turbine power would be applied more rapidly as pitch increased. The essential element of the system-rapidly getting to 100% pitch for quiet operation-was maintained. We returned the shaft idle button to its original bells mode function. Finally, we made the RPM order indication blank below 100% pitch to reduce (but not eliminate) RPM ambiguity. While we spent much effort in the trials trying to develop balanced twists, the final design did not achieve that goal completely.
The DDG-51 throttle control system has three different tables: one for trail shaft, one for split plant, and one for full power. Above 100% pitch at full power, the split plant and full power tables are identical. The control system lead designers had significant steam experience. They developed a method to simplify commands, especially where the pitch and RPM settings differed from split plant to full power. The programmed control lever (PCL) is calibrated from -3.3 to +10.0. A numeric setting was designed to produce the same speed in split plant and full power. In theory, ship speed was a specific integer multiple of the PCL setting. The conning officer could order "all engines ahead plus 2.0" and always get the exact same speed; no lookup table was required. This method of engine orders was never understood and it never took hold. For one thing, it did not work in trail shaft mode. Also, depending on specific ship speed trials and system calibrations, ship speed might vary from this fixed integer multiple. The conning officer usually gives a speed order-which requires the lee helm to refer to a pitch and RPM table to set the throttles-or provides the pitch and RPM order directly. There may be a DDG-51-class ship that uses PCL numbers, but she probably is the exception.
First and foremost, this design achieved the ultimate goal of absolutely quiet ASW performance. Unintended consequences, however, included a system with potential confusion in translating speed orders to pitch and RPM commands at low speeds, differing slow speed performance depending on plant mode, and unbalanced twisting performance for standard orders. Commanding officers have learned that, because a 1/3rd twist has little authority, they must add throttle quickly when quick response is needed at slow speed and they must remove it quickly. Also, they must learn to work with the unbalanced standard twists.
Observations for Future Classes
Predictable throttle response for maneuvering is critical. While confusion should be minimized in any case, there may well be a need for different control modes- such as one that is optimized for quiet, slow speed ASW and one that is optimized with the required response for maneuvering.
When designers with considerable experience state that a design is unworkable, they may be correct. It is best to take note of their advice.
The real proof of a throttle control system is in ship performance at sea. The design should not be frozen until the system is proven at sea and unintended features are removed. If it depends on a different method of commands, this must be carefully considered prior to implementation.
Captain Hiser was commissioning engineering officer on the Arleigh Burke (DDG-51). He later commanded the Paul Hamilton (DDG-60) and is now technical director of the Aegis Ballistic Missile Defense program.
Industry Can Teach Us How to Improve Evaluations
Commander Cathal S. O'Connor, U.S. Navy
In their books, the current and former chief executive officers (CEOs) of General Electric, IBM, and Honeywell International (Jack Welch, Lou Gerstner, and Larry Bossidy) stress the importance of accurately evaluating, identifying, and cultivating the leadership talent pool in every organization. They believe the people process is the most important one-more important than daily operations, plans, and long-term strategy. Bossidy says, "To put it simply and starkly: If you don't get the people process right, you will never fulfill the potential of your business."1
At the deck-plate level, the Navy's people process consists of training, evaluating, and counseling sailors on their ability to execute tasks. In today's fitness report and evaluation system, we have avoided documenting weaknesses unless they were egregious enough to disqualify the officer or sailor from advancement or selection for the next career milestone. This is in part the result of a process that emphasizes what is done correctly. Because we differentiate by degrees of success, selection and promotion boards must discern the evaluator's intent from a spectrum of qualifiers: for example, outstanding, exceptional, and very good. By doing so, evaluations avoid telling the whole truth and arguably keep people from reaching full potential.
But GE, IBM, and Honeywell do not believe in fluffy evaluations. Each made a point of driving realism, pragmatism, and openness into its systems for evaluating, differentiating among, and rewarding its personnel. Welch explained that OE's evaluations "include photographs and miniature biographies of each executive . . . accompanied by a nine-square grid, like a tic-tac-toe box in which one "X" has been filled to show the manager's potential and performance. . . . The criteria used to place that "X" rely heavily on our corporate objectives-the four E's (very high energy levels, the ability to energize others around common goals, the edge to make tough yes-and-no decisions, and finally, the ability to consistently execute and deliver on their promises) as well as our critical initiatives: customer focus, e-business, and Six Sigma leadership. Under each picture, some quick capsule comments highlight a manager's pluses and minuses. Behind these summaries are the backup details of accomplishments and development needs."2
Gerstner, on the other hand, described in a more general way what he was looking for in his top executives, the 300 members of IBM's Senior Leadership Group. "Our answer was to create a set of common attributes that we wanted all of our leaders to have, and to formalize them as IBM Leadership Competencies. . . . The competencies became the basis for evaluating every executive in the company."3 (See Figure 1.)
Finally, Bossidy, who served with Welch at GE before moving on as CEO at Allied Signal and now Honeywell, makes the case that "a good, candid assessment talks about the things a candidate does well and the things he or she must do better. It's that simple. It doesn't use words that don't say anything. It's very straightforward. It's specific. It's to the point."4
Given that more than 60% of the Navy's budget is spent recruiting, training, and retaining the force,5 and that reduced manning will provide fewer personnel to develop into leaders, it would seem that giving honest, direct, and unemotional evaluations would immediately benefit the command and the individuals. These evaluations would identify the officer or sailor who repeatedly executes tasks, shows ingenuity in overcoming challenges, turns less difficult tasks into opportunities to push the envelope, and does so without burning out his people or himself.6 Such a system would facilitate coaching people, recalibrate those going astray early, and give them useful feedbackthey can read and discuss with their reporting senior. I believe the Navy's current systems do not provide these attributes.
Some will argue the last thing we need is new officer fitness report and enlisted evaluation systems, holding that introducing another system of evaluating and mentoring will hinder good careers as leaders adjust to new paradigms. Perhaps that is so. But the fact remains: Navy officer and enlisted evaluations are not honest, straightforward assessments. Moreover, training and feedback can mitigate the dangers of introducing new systems.
The challenge is to combine the honesty that works in industry with Chief of Naval Operations Admiral Vern Clark's guidance to report on "efforts and quality of results in fostering a command and workplace environment conducive to the growth and development of personnel."7 Can we do so and maintain the "promotable, must promote, early promote" system that forces us to make the hard decisions and differentiate between people? I think so.
As an example of what can be done, I modified Honeywell's Continuous Improvement Summary8 to an officer's fitness report on "Commander A. B. Charles." (see Figure 2.) The top third identifies him, provides a digital photo, and lists assignments, awards, and qualifications; the evaluator also rates him on seven skills and five measures of future potential with a black arrow indicating the mean. These mean scores are then used in a selection or promotion board to plot the distribution of evaluated personnel across a skill versus potential graph, where high skill and high potential (5/5) is the best possible result.9
The middle portion examines the command's highs and lows and looks ahead to future challenges. It details Commander Charles's key strengths and weaknesses and provides a brief plan to correct the missteps of the past and strengthen weaknesses.
At the bottom of the page the commodore gives Charles a "must promote," assesses his short- and long-term potential, and ranks him numerically with his contemporaries. The CO has done some superb work in both his engineering and antisubmarine warfare (ASW) training and readiness efforts. If his air defense and strike warfare proficiency improve markedly, he would make a good squadron commodore. If not, his ASW expertise and ability to innovate would make him a good fit for the ASW Center of Excellence. Finally, the cumulative, trait, and summary averages show the officer where he ranks against his peers and against all commanders the commodore has evaluated in the past.
The commodore e-mails the drafts of his fitness reports to the strike group commander; a week later, they discuss them face to face (or by video teleconference if deployed.) Once they agree on the high-skill and high-potential officers, appropriate marks, and how to best develop them, the commodore presents them to his COs. It is clear that they can benefit from their senior's perspective. In addition, as was demonstrated during the last revision of the fitness report and evaluation system, creating reports in isolation can needlessly hinder the careers of good officers and sailors.
Vigorous and open discussion of who is good and who is not can reveal much about the reporting officer's priorities, commitment to the process, and willingness to lead and honestly evaluate his people. Jack Welch speaks enthusiastically of a business leader at GE who stood up to him and fought for his people.10 He believes it teaches him as much about the leader as the person being evaluated. At the same time, a less intrusive alternative would be to have the next senior in the chain of command review the report, make his comments, and return it to the person being evaluated.
The Course Ahead
The hardest part of any new system is putting it in action. Larry Bossidy provides a road map for implementing cultural change:
* Clearly tell people the results you expect.
* As a key element of the coaching process, discuss how to get those results.
* Reward people for producing the desired results.
* If they come up short, provide additional coaching, withdraw rewards, give them other jobs, or let them go.11
Continuing on my example, the commodore issued the following guidance to Commander Charles during his prospective CO briefings:
"Welcome aboard. The Zumwalt is a great ship and she's lucky to have an officer of your breadth of experience as CO. Our strike group commander recently gave us his guidelines for the new fitness report and evaluation system, now called the report system. I'll pass it on to you as my guidance:
* I expect you to get me your inputs one week ahead of time. Fluff will be returned for immediate rework.
* Build reports as you go-last-minute work shows you don't care.
* Fight for your people with documented facts, trends, and measures of effectiveness.
* You can expect that I will ask you hard, probing questions on your scores, promotability choices, and mentor plans.
* I will inform you of what I learn from discussions with my boss about performance reports.
* I respect the COs' calls if they can support them.
* We will learn this process together and will learn more with each "dialogue."
* Focus on progress over time versus perfection today.
* The Navy needs us to do this honestly, fairly, and unemotionally.
* I recommend you pass this on to your crew once you take command so they know where you and I stand.
The CNO held an all-hands call recently and one of the ships was put on report for gun-decking the counseling part of the system. I won't tolerate that. If you're not willing to personally develop your executive officer, department heads, and master chief, you're probably the wrong person for this billet. Likewise, I expect you to train them and have them justify in detail their reports to you. It's the only way they are going to learn how to apply this key aspect of leadership.
I guess the one question that is left hanging out there is how the Navy will handle the CO and XO who choose not to participate. Is the Navy ready to relieve the CO who executes all tasking on time, but grinds up his people and pays lip service to the report and counseling process? I hope I don't have to go there. But if we are serious about giving honest feedback and tracking success, failure, and development over time, I'll have to.
You see, Commander Charles, the Navy's center of gravity has shifted dramatically from platforms to people over the past 50 years. This requires an equally dramatic shift in how we crew, train, and equip the fleet. The Navy's young men and women deserve honest, straightforward, and unemotional reports that evaluate their skills and potential, counsel them on their weaknesses, and coach them as they become the leaders we need today and for tomorrow.
1 Larry Bossidy and Ram Charan, Execution (New York: Crown Business, 2002), p. 141.
2 Jack Welch with John A. Byrne, Jack: Straight from the Gut (New York: Warner Books, 2001), pp. 158-65.
3 Louis V. Gerstner Jr., Who Says Elephants Can't Dance? (New York: Harpers Collins, 2002), pp. 209.
4 Bossidy and Charan, Execution, p. 134.
5 Adm. Michael Mullen, USN, "Sea Enterprise: Resourcing Tomorrow's Fleet," U.S. Naval Institute Proceedings, January 2004, pp. 60-63.
6 Bossidy and Charan, Execution, p. 133.
7 NavAdmin message 213/02 July 2002.
8 Bossidy and Charan, Execution, p. 153.
9 Welch and Byrne, Jack: Straight from the Cut, p. 164.
10 Welch and Byrne, Jack: Straight from the Gut, p. 164.
11 Bossidy and Charan, Execution, p. 86.
Commander O'Connor is assigned to the Force Structure, Resources, and Assessment directorate (J-K) of the Joint Staff in Washington, D.C.