LPD-17

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I. EXECUTIVE SUMMARY

On 10 December 1997, TEAM 17 hosted representatives from NAVSEA, NSWC-Carderock, Fleet Training Group, and COMPHIBGRU Two in the LPD 17 War Room at Expeditionary Warfare Training Group Atlantic to discuss current Navy and International visual display requirements aboard ship and their impact upon planning for the Advanced Enclosed Mast/Sensor System (AEM/S). This workshop is part of LPD 17’s Design for Ownership process where Fleet warriors, operators, maintainers and trainers contribute to ship design and system integration.

TEAM 17 is currently reviewing the applicability of the Advanced Enclosed Mast Sensor System and AEM/S optional designs for LPD 17. Intended to facilitate maintenance, limit corrosion and reduce radar cross section, the innovative shape and composition of the AEM/S will provide a significant upgrade to the LPD 17. As potential mast designs were reviewed, Team 17 recognized that a key variable in the design was the requirements for signal flags, pennants, day shapes, and dress ship in the 21^st century. With a January deadline to select a near-term AEM/S baseline option, TEAM 17 scheduled this workshop.

Mr. John McIntire, NAVSEA 03D3/PMS 317D, initiated the workshop by outlining the goals as follows:

• Review the requirements for flags, pennants and day shapes,
• Determine which ones are strictly ceremonial or traditional and which ones have a military use
• Discuss difficulty in changing any of these requirements.
• Discuss how these requirements can be met by other existing methods or alternate means (e.g., electronic billboard display on the side of the mast, enhanced signal lights, etc.)
• Solicit warfighter/operator input on AEM/S options

Discussion continued as Mr. Jeffrey Benson of NSWC briefed the attributes of the AEM/S, the rationale for its design, and background on its development and trials on USS ARTHUR W RADFORD. Team 17’s Kendall King outlined current visual display requirements and then facilitated discussion on projected needs. Mr. Lenny Wanex of NAVSEA 03W4H facilitated a discussion on the identification of performance requirements for alternative close-in tactical communications systems. Mr. Steve Farley of NAVSEA 03T1 concluded the formal presentations by outlining eight proposed design options for the Advanced Enclosed Mast/Sensor System.

The results of the workshop validated visual display requirements, established the need for LPD 17 to accommodate those requirements, and then centered upon a recommended design option for the Advanced Enclosed Mast/Sensor System. A port and starboard, deck mounted counterbalanced, hinged mast was recommended as the best option for LPD 17 to comply with current visual display requirements. The signal masts would only be raised when needed, enabling RCS reduction to be mandated. Future efforts should work toward developing technological solutions that alleviate the need for the current signal flag support structures so as to accommodate next-generation low signature ship designs.

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One of the strengths in the planning and design of LPD 17 has been the input and support of Sailors and Marines. Good ideas and suggestions have been submitted and are now being considered for incorporation into the ship design. When the issue arose as to which baseline Advanced Enclosed Mast/Sensor System design option would best serve the future Sailors of LPD 17; Team 17 convened a Design for Ownership workshop. Hosted on 10 December 1997, representatives from NAVSEA, NSWC-Carderock, Fleet Training Group, and COMPHIBGRU Two met in the LPD 17 War Room at EWTGLANT to discuss current Navy and International visual display requirements aboard ship and their impact upon planning for the Advanced Enclosed Mast/Sensor System (AEM/S).

The Advanced Enclosed Mast/Sensor System is currently being tested aboard USS ARTHUR W. RADFORD and is being planned for inclusion on the LPD 17 Class. It is intended to reduce maintenance and enhance ship topside access, improve radar capabilities and support reduced radar cross section (RCS) – attributes that are desirable on LPD 17. As part of the planning for the mast, TEAM 17 has embarked upon an effort to examine form, fit and function on LPD 17 and to consolidate these efforts as a proof of concept for CVX and DD-21. Toward these ends the LPD 17 Topside team was required to investigate and then recommend a near-term baseline design option for further development by January 1998.

Participants from Fleet Training Group and COMPHIBGRU Two were invited during the workshop to review visual display requirements, help define and convey military and operational uses for these displays, and then assist in creating a AEM/S design that will serve LPD 17’s 21^st Century needs. COMPHIBGRU Three also provided input. The agenda and the list of attendees are provided in Appendices A and B. The initial welcome/overview presentation is provided in Appendix C. Portions of the other presentations are included graphically in the Discussion section, Part III.

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Welcome and Overview. Mr. John McIntire of NAVSEA PMS 317D/03D3 opened the session by providing background on the LPD 17 and its Design for Ownership (DFO) process. In design for ownership the planning and design of LPD 17 is dependent upon comments, suggestions, and recommendations from the Fleet and Marine Corps to ensure that the ship will meet their requirements and needs. The Visual Display and Advanced Enclosed Mast/Sensor System workshop is a typical example of TEAM 17 seeking Fleet input prior to choosing a baseline design option. In addition, he indicated that the session could also serve as a forum for beginning discussion about future technological solutions to visual signaling and displays.

Mr. McIntire reiterated the key issue for the workshop was that the use of conventional methods for displaying signal flags will probably not be an option for the ultra-low signature ships of the future due to the radar cross section of the structure from which the flags are flown. While the LPD 17 could accommodate display via current methods and meet it's signature requirements, the same may not be true for future combatants. Therefore now is the time for LPD 17 to realize the advantages that the Advanced Enclosed Mast offers of lower radar signature, simplified mast construction, and lower cost while still serving Fleet visual display needs.

Focusing on this issue, the goals of the workshop were outlined as follows:

• Review the requirements for flags, pennants and day shapes
• Determine which requirements are strictly ceremonial or traditional and which ones have a military or legally required
• Discuss difficulty in changing any of these requirements.
• Identify performance requirements for alternative visual signal methods
• Discuss how these requirements can be met by other existing methods or alternate means (e.g., electronic billboard display on mast, enhanced signal lights, etc.).
• Solicit warfighter/operator input on AEM/S options

AEM/S Background. Mr. Jeffrey Benson of NSWC – Carderock followed with an introduction to the Advanced Enclosed Mast/Sensor System and background on its testing aboard USS ARTHUR W RADFORD.

The design itself seeks to limit radar signature by shape (hexagonal shape and 10 degree slope) and enclosing key radar components. The mast is a large composite structure, 711/2 feet high and weighing 30 tons, whose structural integrity has been demonstrated by testing. The upper half of the mast is radar frequency transparent, permitting the transmission of selective radar frequencies and integrated communication energy through the mast’s surface. The lower half of the mast is radar reflective and the entire mast is part of an integrated EMI/EMP management system.

Testing to date on USS ARTHUR W RADFORD and lessons learned from the DDG-51 program has revealed payoffs in radar cross section reduction (RCSR). Exposed mast-mounted HM&E equipment, combat system and comms antennas dominate ship radar cross section. At the same time, radar-absorbing materials and structural shaping do not provide adequate RCS reduction. LPD 17’s stick mast and mast equipment accounts for 8% of the ship’s RCS while Applying AEM/S to the LPD 17 architecture will demonstrate "substantial reduction" in mast and mast Equipment RCS.

Figure 1 provides a baseline side view of the mast.

The resulting advantages to LPD 17 provided by the AEM/S appear to be substantial as concluded by Mr. Benson. These include the potential for meeting topside radar signature reduction goals and improving sensor performance while reducing maintenance. At the same time the AEM/S would reduce ownership costs by facilitating sensor upgrading and modernization over the 40-year service life of the class. All weather accessibility to mast sensor systems will also be an attribute to installing the AEM/S on LPD 17 as well as providing a proof of concept for CVX and DD-21.

The audience raised several questions at this point. (1) A cone shape was considered, but rejected for the AEM/S – a cone always gives a radar return while a faceted (hexagonal) shape will provide a lower signature median and only when the emitter is perpendicular to a specific facet or side. (2) Topside weight was a consideration and the differences between the stick and AEM/S mast is about an equal tradeoff. (3) The mast can be painted several times but the full number of coats to be applied before degradation of mast performance has not been determined. Embedded coloring was recommended. (4) There is a possible impact from stack gas residue, but cleaning systems, such as a semi-automatic sprinkler or hose system are being considered. (5) Component change out is facilitated by a mast detachable joint, i.e. that allows the top to be lifted off to replace a radar. The Advanced Enclosed Mast/Sensor System on LPD 17 is depicted in Figure 2.

Figure 2. Advanced Enclosed Mast/Sensor System on LPD 17

One element of the AEM/S planning led to this workshop. The optimum mast design would not have a provision for signal halyards because such accessories detract from RCS reduction efforts. Therefore, how are visual display requirements on the AEM/S accommodated?

Visual Display Overview. During the workshop a mast visual display requirements presentation was provided. Refined by direct input from COMPHIBGRU Two and FTG operators, this overview was intended to establish requirements for visual displays, the references or source documents for those requirements, the impact on AEM/S (number of halyards), the identification of performance requirements for replacement systems, - and a possible recommendation on future shipboard visual signaling needs. The results of the presentation and associated dialogue led to Table 1.

Visual Display Conclusions: In examining the implications of Table 1, the group came to the following consensus for LPD 17. If only the minimum number of halyards were installed, the ship design would need to allow for:

• One halyard from the foremast for ensign, Church Pennant or foreign ensign during dress ship.
• One halyard from the after mast for distinctive displays (i.e. commissioning pennant or personal flag and Dress Ship Ensign)
• One halyard or a pole for COLREGs Day shapes
• Attachments on the AEM/S for full dress ship cables
• Two halyard needed for International/INCSEA signals
• Three halyards per side needed for tactical signals.

Discussion also included input on operational usage of signal flags. COMPHIBGRU Two and FTG representatives as well as comments submitted by COMPHIBGRU Three established the need for retaining the use of signal flags for tactical reasons and for communications with Allies, Friendly, and Partners in Peace navies. Although it was understood that such visual displays may eventually become outdated as future low RCS signature 21^st century ships enter service, the LPD 17 may very well have to be a transition ship – accommodating visual display until the capability is replaced.

For instance, in a swept channel/port entry/sortie, daylight transit signal flags remain a viable means of tactical maneuvering communications during electronic silence. It remains the fastest means for silent communications that is fully understood by all navies, without language interpretation challenges. The consensus of the workshop was that signal flags remain a requirement for the LPD 17 class design until alternative means are uniformly accepted internationally.

The workshop also addressed other visual display requirements currently in use that may not be essential. Each is a candidate for further consideration and possible initiatives to change the requirements as follows:

• Union Jack flown from yard arm. General Court Martials and Courts of Inquiries are not often held aboard ship and an alternate means of indication might be considered or the requirement dispensed with.
• Requires change to Navy Regs and to NTP 13.
• Saves one halyard when signal flag halyards are no longer required
• Award Flags. PUC, NUC, MUC (Presidential, Navy and Meritorious Unit Commendations) and Battle E are already displayed as part of bridge wing commendation displays. Alternative means could be found to display other award flags and pennants presently not displayed on the bridge wing.
• Requires change to NTP 13
• Saves one halyard
• Absentee pennants/SOPA. (Senior Officer Present Afloat). Absentee pennants provide a visual cue as to whether the commanding officer, embarked unit commander or embarked chief of staff is onboard a ship. In 1995 it was not used in the Sixth Fleet because it also provides visual cues for terrorists – and is therefore considered to be non- essential. SOPA provides a similar indication
• Requires change to NTP 13 and ATP 1
• Saves three halyards per side inport when signal flags are no longer required
• PREP. When used for colors in port, voice/radio communications and whistle signals parallel it.
• Requires change to NTP 13 and ATP 1.
• Saves one halyard

Note: A sufficient change to ATP 1 might be to make certain displays, (e.g. absentee indicators) optional, rather than to delete the meanings or the use of these flags all together.

A brief discussion was led by NAVSEA 03W4H to determine rough performance requirements for visual display replacement systems. Based on our current capabilities with signal flags, the replacement systems would have to:

1. Be visible with aided vision for the following conditions and ranges:
• Clear day: 5 miles minimum
• Cloudy day: 3 to 5 miles minimum
• In rain or fog: No visibility requirement
2. Be visible for 180o minimum from each side of the ship
3. Be repeatable for 360o coverage
4. Be able to be encoded within 5 minutes
5. Be able to be decoded within 2 minutes
6. Be internationally understood
7. Not violate Emission Control Communications (EMCOM) conditions while operational
8. Maintain line of sight
9. Not require use of cryptological devices
10. Be able to be displayed continuously as required for operations without degradation or alteration

An optimum replacement would be one that could be sent from a keyboard, could be automatically detected by a sensor on the receiving ship and receipted for, automatically decoded and displayed without human intervention, visible at longer ranges both day and night (and all weather), and have reduced counter-detection. Such a system could be used to replace signal flags as well as flashing light communications, but it would have to be readily compatible or transferable to Allied and Friendly navies.

Design Discussion. Mr. Steve Farley, NAVSEA 03T1, concluded the presentations with an overview of the AEM/S design options. Pros and cons for each option were also presented. The resulting discussion of each item led to a recommended option for LPD 17. Three comments were expressed as designs were considered: (1) The ship will not always need minimum RCS (inport, etc.); and (2) At times when minimum RCS is required the need for electronic silence and visual signaling and communications (as a substitute for electronic communications) will be paramount; (3) That signal flags, pennants, day shapes, and halyards were not RCS offenders – rather the support structure (i.e. yardarms, masts, etc.) required for their display were the offenders.

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The following conclusions were derived from the workshop:

1. 21^st Century Requirements

• The conventional support structure that is required to display signal flags would not support the ultra-low signature requirements of future ships.
• While the LPD 17 can conventional signal flags support structure and meet it's signature requirements, the same may not be true for future combatants.
• LPD 17 needs to realize the advantages that the Advanced Enclosed Mast offers of lower radar signature, simplified mast construction, and lower cost while still serving Fleet visual display needs.
• Ships that will be outfitted with these AEM/S systems will still be required to conduct some sort of visual communications with USN or Allied navies necessitating this need aboard LPD 17.

• Meets topside radar signature reduction goals
• Improves sensor performance while reducing maintenance
• Reduces ownership costs by facilitating sensor upgrading and modernization over the 40-year service life of the class.
• Provides all weather accessibility to mast sensor systems.
• Provides proof of concept for CVX and DD-21.

• Single halyard on foremast for ensign, and foreign ensign for dress ship and for award pennants in port
• Single halyard on aftermast for ship distinctive mark (i.e., personal flag, command flag, or commission pennant)
• Single halyard or pole for day shapes (Note: The only operational requirement for LPD 17 to use three halyards would be for conducting underwater operations or to use two halyards if restricted in ability to maneuver while towing with a tow greater than 200 meters and COLREGs provide exceptions for war ships).
• Attachment points on masts for Full Dress Ship
• Two halyards for International Signals/Treaty (INCSEA) signals
• Up to three halyards per side for Tactical Signals from signal book, etc.

• Primary means of signaling in electronic silent, tactical situations such as swept channel, port entry and sortie, silent tactical maneuvering, silent Unreps, etc. and in an emergency situation such as loss of power
• Significant means of communicating with Allies and Friendly navies since internationally understood
• Specified means of communications for treaty compliance such as the Incidents at Sea Agreement

• Uniformly (internationally) recognized signals of information such as diving, explosive handling or refueling,

• Whether used for traditional or ceremonial purposes, efforts could be initiated to delete requirements for the following in the near-term:

• In the long term, it was envisioned that mast designs should retain capability to fly the national ensign, commissioning pennant/command flag/personal flag, and church or Jewish pennant from the masts and the national ensign/Union Jack from flagstaff/jackstaff inport. The traditional use of full dress ship, friendship lights, and Christmas lighting also necessitate appropriate mast attachments. Whether used for traditional. ceremonial or operational purposes, efforts should be initiated to develop alternative methods for meeting close-in tactical communications needs in the long term for follow-on low RCS ship- building programs as follows:

• For LPD 17 an engineered solution to meet LPD 17 transitory requirement between current and 21^st century signal flag usage is recommended. The separate signal mast would be counterbalanced using simple whip antenna technology to reduce the concern for too many moving parts. The signal masts would only be raised when needed, enabling RCS reductions to be maintained. This option requires no immediate changes to flag usage documentation and current visual display requirements while retaining signal flag communications with Allies and Friendly ships during periods of electronic silence.
• For follow-on low RCS signature ships, a technological solution for replacing conventional methods of visual displays should be developed that is compatible to other ships and other navies. Designers should consider growth in this area, pursuing such options as Omni-directional modulated light or lasers.
• Option 4B was the preferred AEM/S design option for LPD 17.

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1. PMS 317 use AEM/S Option 4B near term baseline design planning.
2. 2. PMS 317 will pursue reducing flag size requirements on LPD 17
3. 2. PMS 317 initiate input via sponsor or through the Naval Expeditionary Warfare Engineering Product Team for determination of future visual signaling requirements and appropriate.

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Appendix A

LPD 17 Visual Display and Advanced Enclosed Mast/Sensor System Workshop Agenda 10 December 1997

0830 Introduction/Welcome	J. McIntire, PMS 317D
0850 Overview of Advanced Enclosed Mast/ System Development	J. Benson, NSWC-CD
0930 Identification of performance requirements for alternative close-in tactical communications systems.	L. Wanex NAVSEA 03W4H
0910 Review of requirements relating to signal flags, pennants and day shapes and visual communications requirements (Includes COLREG Requirements)	K. King, Ownership Team (Team 17)
1000 Military uses for signal flags, et al and possible alternatives in the 21st century	Round Table Discussion
1030 Review of Advanced Enclosed Mast Options For LPD	S. Farley, NAVSEA RCS Engineer
1100 Discussion of signal flag alternatives and Mast design options	Round Table Discussion
1145 Summary and Wrap up	J. McIntire, PMS 317D

 

LPD 17 HOME PAGE http://lpd17.nswc.navy.mil

LPD 17/EWTGLANT Warroom: Phone 1-800-445-1916, Fax 757-464-8599

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Appendix B

WORKSHOP

Attendees

10 December 1997

NAME	ORG	PHONE#	FAX#	E-MAIL
Benson, Jeff	NSWC Team 17	(301) 227-1087	-1020	benson@oasys.dt.navy.mil
Berrios, Gilberto SMC	FTG	(757) 363-4151
Boozer, Joe SMCS	FTG	(757) 363-4151
Campbell, Wink	ASC	(757) 464-8604	464-8599	w.campbell@asc.livenet.net
Casper, Robert, Lt	CPG-2	(757) 464-8677		rcasper@hq.cnsl.spear.navy.mil
Erikson, Mark CDR	N8 CPG-2	(757) 464-8699		merikson@hq.cnsl.spear.navy.mil
Farley, Steve	NAVSEA 03T1	(207) 442-5284		sfarley@biw.com
Hungerford, Milo QMC	FTG	(757) 363-4809
Jones, Betty	A&T, Team 17	(703) 418-8690	-8651	bljones@kryten.atinc.com
King, Kendall	ASC, Team 17	(757) 424-3711	420-6910	k_king@asc.livenet.net
Lorenzawa, Richard	QMCS FTG	(757) 363-4809
Luebke, Bill CAPT	PMS 317	(703) 413-4999	418-2527
Marsh, Robert SMC	FTG	(757) 363-4151
McIntire, John	NAVSEA 03D3	(504) 437-3542		jgmcintire@avondale.com
Picotte, Len	ASC, Team 17	(757) 424-3711		Picotte.Len@ascacc.com
Rockwood, James	CPG-2	(757) 464-8815
Wanex, Lenny	NAVSEA 03W4H	(703) 602-1895	-4746	wanex_leonard_a@hq.navsea.navy.mil
Weingart, Steve CDR	FTG OIC	(757) 464-8888		slgart@exis.net

 

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Appendix C

Welcome and Overview Presentation







 











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