An explanation via e-mail from a former USN LSO well experienced in all things NavAv. His text reminded me now that I have a video of a VX-23 test pilot at the 2014 HOOK meeting explaining what they do for testing aircraft at NAS Patuxent River. I THINK (I'll have to find the video and post the link) he says in the clip of the Goshawk T-45C arresting off center that if they go wider than 20 feet it takes a day to reset the single arrestor gear (or repair it) at the station - in all things as the test pilots take aircraft and other gear to their limits they have to be very careful - but it is fun he said. Meanwhile here is the former LSO explanation:
"The USN arresting gear engines used fleet wide have been the Mark 7 Mod 3 system. The
Mod 4 is installed on CVN-76 and later. They are essentially the same capability wise.
The two questions do not have single number answers. This is due to the dynamic
variables of an arrested landing.
The cross deck pendant has a tensile load limit of about 96,000 lbs. The arresting
gear engines have a 10,000 psi limit.
The arresting gear system is designed to handle any combination of off center hook
engagement and line up deviation up to those two limits. The engines have built in
protection to prevent head to head collisions inside the engine itself due to deviant
arrested landings.
Whether either of the two limits is approached is mostly dependent upon two things,
touch down speed and relative head wind at touch down. Higher than optimum touch down
speed is bad while higher relative head wind is good. We assume that the arresting
gear is set to the correct weight for the airplane that is landing, (F/A-18A/B/C/D is
36,000 lbs). If that is set wrong, as in too low, then the Constant Runout Valve
cannot function as designed and damage to the arresting gear engine may result, the
cross deck pendant may fail, or both. If it is set too high then structural damage to
the airplane may result.
If you want a single number for off center, use 20’. That what is used as a maximum in
testing by the USN.
And 20’ is for a lined up airplane that is not drifting at
touchdown. The more drift present at touchdown the less distance off center can be
tolerated.
It would be a very rare event that a far off center touch down, or a significant
drifting airplane landing would occur.
The LSOs simply don’t let approaches outside
proper parameters past the wave off window for obvious reasons. The ladder lines on a CV flight deck landing area are 80’ apart, which means if you
touch down 20’ off center you are really doing a shit job of piloting. We Naval
Aviators are way TOO good to attempt that even without the LSOs keeping that from
happening if we tried it."
Here is the video which explains
'off center engagements' (17 to no more than 20 feet) at the time on the first URL:
Carrier Suitability F-35C SR&R Hook14=318