|
|
От
|
Дм. Журко
|
|
|
К
|
Skvortsov
|
|
|
Дата
|
11.01.2012 13:56:13
|
|
|
Рубрики
|
Флот; ВВС;
|
|
Спасибо. Не мог никак найти, почему-то.
На всякий случай текст главы отчёта:
Arresting Hook System (CV variant): There are significant issues with respect to how the CV variant's AHS interoperates with aircraft carrier based MK-7 arresting gear. Roll-in arrestment testing at NAWC-AD, Lakehurst, resulted in no successful MK-7 engagements (0 successes in 8 attempts). Root cause analysis identified three key AHS design issues: (1) the aircraft geometry has a relatively short distance between the aircraft's main landing gear tires and tailhook point (when lowered), (2) tailhook point design was overemphasized for cable shredding features versus ability to scoop low positioned cables, and (3) tailhook hold-down damper performance is ineffective to support damping of small bounces relative to runway / deck surface profiles.
As shown in Appendix Figure 8, page A-9, the F-35C's main landing gear to tailhook point distance is 7.1 feet. Accordingly, when the aircraft's main landing gear rolls over the arresting cable, the responsive dynamics are such that the cable lies nearly flat on the deck. Comparing similar geometries with other, currently operating carrier based aircraft which range from 30.2 feet (C-2) to 14.6 feet (T-45), the F-35C is an outlier. The current F-35C tailhook point design (Appendix Figure 9, page A-10) was based on the F/A-18E/F design which has a blunt face to better provide cable shredding protection versus scooping. However, the F/A-18E/F's geometry places the distance of its main landing gear to tailhook point at 18.2 feet; a much longer distance than the F-35C. Since there is more distance in the geometry, the trampled cable has enough time to respond and flex back toward its original setting position by the time the tailhook point intercepts for arrestment. The hold-down damper contributes to overall aircraft arresting gear poor performance by allowing the tailhook to bounce excessively.
To address these issues, the program is designing modifications to the tailhook point and hold down damper components. The proposed hook point redesign in Appendix Figure 10, page A-l 1, both reduces the blunt face geometry with a more pointed front end and lowers its apex point by 0.5 inches (68%) such that it is now below the arresting gear cable centerline to better enable scooping performance. The proposed hold down damper redesign will consist of modifications to the AHS actuator damper such that a lesser number of orifices will temper tailhook bounce dynamics (Appendix Figure 11, page A-12). The AHS redesigned components will undergo Monte Carlo probability of engagement analysis as a lead-in effort for design review which is scheduled in December 2011. Following successful design review, the plan is to manufacture the redesigned components and then conduct rolling engagements at NAWC-AD, Lakehurst in April 2012.
With corrective action still in development, the AHS is considered an area of major consequence. If the proposed redesigned components do not prove to be compatible with MK-7 arresting gear, then significant redesign impacts will ensue. Accordingly, the program is conducting a formal trade study to assess options beyond AHS redesign. One option includes adjustments of AHS airframe location. However, since arrestment loads are significant and the aircraft has certain constraints with respect to engine location and survivability considerations, any readjustment of AHS location will have major, direct primary and secondary structure impacts.
Since rolling engagements in April 2012 represents only the initial stages leading into full carrier suitability demonstrations of the F-35C, complete knowledge of how truly compatible AHS redesigned components perform under nominal and off-nominal approach to engagement conditions will not be realized until well into the program's developmental test timeline. This issue represents a major concurrency risk which would have a significant retrofit impact to LRIP aircraft already delivered a large re-adjustment to the current F-35C production process build-up flow and, in many aspects, invalidate previously obtained developmental test and evaluation data.
Conclusion: Major Concurrency Risk - Sign, ficant redesign risk and options are unknown at this