UJTS RFI QandA.pdf

UJTS RFI Q&A

Date Posted: 29 June 2020

Questions and Responses from UJTS RFI one-on-one sessions

1) A question was posed concerning Electromagnetic Environment Effects (EEE) requirements, seeking unclassified details so they can be addressed in response to the RFI.

Consistent with Note (1) of Appendix A, the Navy’s requirements can be traced back to MIL-STD- 461G (current revision) for box/subsystem level Electromagnetic Interface (EMI) testing and to MIL- STD-464C for the platform EEE testing. Both of these standards are freely available on the internet.

2) A question was posed for the definition of sustained buffet-free load factor.

MIL-STD-1797B defines acceptable regions of the flight envelope based on encountering "intolerable buffet" and it defines regions of acceptable or recoverable handling qualities by "A safe margin below [above] the load factor at which intolerable buffet or structural vibration is encountered."

MIL-STD-1797 also references AGARD AR-82 for definitions of buffet levels. Both of these standards are readily available via internet search and can be used for purposes of responding to this RFI.

3) A question was asked concerning critical field length on USN hot day, since there were several definitions of hot day, could we provide which we were seeking?

For purposes of responding to the RFI, “Hot Day” is defined in MIL-STD-3013A, which is readily available via internet search.

4) A question was asked regarding the tire load and deflection analysis, why was it an issue, and were any studies performed to identify the cause of tire usage in the fleet?

Once an aircraft design is established, the landing gear bay dimensions, in conjunction with the landing design, results in constraining the tire size. Navy carrier-based aircraft tire design must be capable of handling all operational takeoff and landing speeds while simultaneously be capable of handling high landing loads from shore-based field carrier landing practice and carrier-based landings. This is further aggravated by the fact the tire could simultaneously land on an arrestment cable which can result in severe deflections of the tire. This combination of constraints and performance requirements results in tire design requirements that have shown to be difficult to achieve on Navy carrier-based aircraft.

5) While there is a sustained Nz requirement, no maximum G requirement was noted in the capabilities document. Can a maximum G requirement be provided to assist with fatigue assessment.

Consistent with Appendix A, the maximum symmetric load factor is ≥7.33G.

6) A question was asked for information on the servicing equipment like camera deck plates and runway lights.

There are several items to consider when designing for deck obstructions and ground clearance.

First, the aircraft shall be designed so in the event of a landing gear failure condition (bottomed out Landing Gear struts and blown tires), the aircraft along with its external stores will clear these obstructions. Second, the aircraft must be able to roll over existing obstacles without damage or loss of aircraft.

UJTS RFI Q&A

Date Posted: 29 June 2020

In general, carrier- based aircraft must be able to cope with deck obstructions up to 6 inches. The Cross Deck Pendant sits at a nominal height of 5.5 inches to the cable center via cable supports. Carrier-based arrestment system uses a cable with a 1.625 inch maximum diameter. The Fast Eddie catapult bubble cover, typically located near the landing zone, climaxes at 5.75 inches tall. In-deck installations, such as lights and cameras, are all under 1 inch and have chamfered edges. These types of obstructions must be considered for static and multivariate landing cases.

For shore based airfields, NAVAIR 51-50AAA-2, General Requirements for Shorebased Airfield Marking and Lighting, is publicly released and provides information on airfield lighting dimensions. Shore-based E-28 arrestment system uses a cable with 1.25 inch diameter. The height above the deck to cable center varies from 4.125 inches to a minimum of 2.625 inches. For the T-45 main operating bases, each runway has a single field arresting cable at each end of each runway, positioned between 1000 and 1750 feet from the runway threshold (exact location differs).

7) A question was asked about whether autothrottle would be required for PLM and would it require physical movement of the throttle.

PLM does require an auto throttle-type system that includes physical movement of the throttle.

8) A question was asked about whether the architecture of Precision Landing Mode currently fielding in Fleet aircraft includes datalink communications with the Aircraft Carrier for landing area aiming.

Precision Landing Mode is an aircraft based system, and does not require a datalink to the carrier. However, certain parameters (IFLOLS Lens Angle and Ship’s Ground Speed) must be provided to the system. This can be done manually by the pilot, or via Joint Precision Approach and Landing System (JPALS) datalink. JPALS is not currently a UJTS requirement, so it is recommended that you assume manual entry of required parameters.