A re-post from back on 30 August,. It was lost in the server meltdown back in Sept, so here it is again.
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Daily Pic – Day 241, Cross Deck Pendant
Or also known as the “wire”. That, when reeved at a 18:1 ratio around a beasty little hydraulic-ram piston/engine that meters hydraulic fluid through an eency-weency little opening (that is adjusted depending on the weight of the aircraft that is landing), is what will stop a 25 ton jet aircraft traveling at 135 knots in about 345 feet. (ed. note: cocktail party trivia to impress your friends with: The arresting gear system of a US nuclear aircraft carrier has an an energy absorbing capacity of up to 47,500,000 foot pounds of energy. That’s a bunch!)
You can imagine how tough this wire has to be. The above-deck span is 110 feet for the two newest carriers (CVNs 76 and 77), and 120 feet for all others. The weight of the wire is about 3.5 lbs per foot, so the 120-foot wire on CVN75 (HARRY S TRUMAN) weighs 420 lbs – which doesn’t sound like much but you have to remember these wires are only 1 7/16-inch in diameter. It has a breaking strength of 215,000 lbs and they are only good for 125 traps (arrestments, landings, grabs, whatever – which is up from the old limit of 100 because of a new inner core design) before they need to be replaced with a new wire. Here is a pic of a couple of stand-bys ready for swap-out:
HST COMPTUEX, June, 2009
The wire itself is, understandably, rather stiff and inflexible when laying in repose upon the wire brackets that support it between 2 to 5.5 inches above the flight deck. This is to ensure there is room for the aircraft tailhook to grab the wire. If it were laying flush on the deck, the tailhook would be unable to grab a’holt of it.
HST COMPTUEX, June, 2009
(There is a cool pic coming up, dear readers. Patience!)
So, now that we’ve gone through how absolutely intense these crossdeck pendants have to be and how robust and manly and strong and all they are, THIS pic is all the more amazing. I had the trusty Canon 50D set to the fastest shutter speed possible and had it snappin’ pics at the 10 frames per second (or whatever it is). What you are seeing is the instantaneous deformation of the CDP by the nose gear of a Hornet as it lands and passes over the wire at 135 knots.
HST COMPTUEX, June, 2009
A split second later the smoke hits from the friction of the tire on the deck and the reaction of the wire hitting the deck in such a rude manner!
HST COMPTUEX, June, 2009
And a split second after THAT….the wire-b-gone as the tailhook snatched it!
HST COMPTUEX, June, 2009
And remember, that is done about every 45 seconds, 15 times every hour and 15 minutes for a fly-day of about 12-14 hours.
Yow-sir!
John Carmichael // Dec 12, 2009 at 1:37 pm
Glad you found it… and reposted… for some reason the 3rd image is my favorite. show’s the power, physics and is an all around great capture of frozen motion.
-JC
John Carmichael // Dec 12, 2009 at 1:37 pm
Oh yeah… GO NAVY! BEAT ARMY!
Kevin // Dec 12, 2009 at 5:15 pm
GNBA! is not defined in reference to “the game”
Online, I find no results.
A simple entry is all it would take.
Results are found for the opposite team though.
Might have spelled it out, but it’s a Navy blog.
Yes, it would cause the cursing of sailors.
!
Boats and barges are wonderful.
Engineers know that, since they design them.
Air Force doesn’t have them.
The Marines get to ride around on them.
Now the friendly rivalry has reached 110.
And many more, I pray.
Volunteers all, who give so much.
You know we are blessed with such young men
!
Kath // Dec 12, 2009 at 5:59 pm
Ok. CRAP!!! Navy won.
Congratulations.
(But this is a good post to rerun, bec. the pictures are so very good.)
Kevin // Dec 12, 2009 at 8:42 pm
Hats off to the Navy!
oklso // Dec 12, 2009 at 10:02 pm
Pinch, do you know if they are still a strike if the hook-point kisses the wire, but doesn’t engage it?
Glenn Cassel AMH1 USN Retired // Dec 13, 2009 at 4:00 am
That little opening is called a metering orifice. It is also in landing gear shock struts, wing fold actuators and such. Trust the AMH1 on this one.
And in the autumn of 1975, on board the Good Ship USS Independence CV62, we rigged the barricade in under two minutes. The Air Boss lost the bet and we got ten gallons of ice cream. Vanilla and Neapolitan, if I remember right.
Yeah, Pinch, I am not a kid anymore.So says the wife, daughter, sons and the doc.
But I still think so!!!!!!!!!!!!!!!!!
Cruise Noorwegen // Dec 21, 2009 at 1:51 pm
Planning on joyning the navy, awaiting scores and test results. Seeing this I feel butterflies….. Thanks for sharing!
Crystal Admiral // Jan 20, 2010 at 7:54 am
Great article. Came across this via Google. Really interesting to also see the wire support too. “Providing a method of raising the crossdeck pedant off the flight deck to ensure arresting (tail) hook engagement of the incoming aircraft.”
Club Golden Beach // Feb 12, 2010 at 4:47 am
What a great pics, just makes me keep on watching. Like the 3rd image a lot, and agree that is clearly shows the power and physics. You have a new blog reader for sure.
Parkeren Schiphol // Mar 2, 2010 at 4:01 pm
Really impressive. Served in the navy for a few years, and this is still something that takes my breath away!
Schiphol aankomsttijden // Mar 30, 2010 at 9:28 am
It just made my heart tick faster, getting a massive adrenaline push from these picks. Made me think back to the time I served! Excellent resource of valuable information and pics that never should get lost. Great job.
Smart Parking Schiphol // Apr 23, 2010 at 10:10 am
Amazing pics, I had to quit my job at the navy due to family circumstances, and seeing this doesn’t make things easier….