FSDreamTeam forum
General Category => Unofficial F/A-18 Acceleration Pack board => Topic started by: burner12 on December 17, 2009, 01:44:05 am
-
I have been watching a lot of clips of flight deck action for the past 22yrs now. And understand most commands, but 1 don't understand is once control of the aircraft is handed over to the cat officer and he tells the pilot to go to full military power by moving his fingers back and forth he then points down the deck, at the gear, and at the green shirt who presses the button. What is he telling the pilot then , right before he touches the deck?
Here is a good example &feature=related from 1:20-1:23
-
This flamboyant Catapult Officer is checking the cat foul line fore and aft and slightly waving his hands to help spin around before touching the deck. The CAT O is in charge of the catapult but not in charge of the aircraft. The Pilot is in charge of his aircraft but wisely follows directions of the yellow shirts on deck. Touching the deck is the ultimate command that cannot be uncommanded because then the cat chap presses the FIRE button with a slight delay before firing (because he has his routine that ultimately might stop the launch - but the CAT O has already finessed that - unless there is an absolute last second hitch with the catapult). That is my take on it.
The Catapult Officer winds up the aircraft to full power (burner or not). Pilot does his checks and then salutes Cat O (who whilst continuing to wind up aircraft seems to return salute). Cat O does his last second check of the cat foul line and then sends 'em on their way. ::)
As you might imagine on a busy deck with another catapult nearby there might be debris or personnel across the foul line for whatever reason. Checking before launch is a good thing to do. There would be official narratives in various PDFs mentioned already on this forum and probably some here would have more personal knowledge of USN procedures.
-
So Spaz you are sayingthat when he points down the deck at the gear and at the green shirt he is signaling the pilot that all is clear of FOD, and they can proceed with the final launch, correct? But why check the green shirt and gear? I understand the deck.
-
He's pointing so that everyone can tell he is indeed checking the areas that he has to before the launch. This way other people (pilot, checkers, cat crew) can all confirm that he did his job.
Also, its actually the Director and not the Cat Officer that gives the pilot the signal to go to military power. He then hands control over to the Cat Officer. 1:16
If there is a need to go into burner, the Cat Officer will give the pilot that signal before launching him. &feature=fvsr 0:16
-
burner12, I'm not understanding your question about the specific Hornet catapult. Probably there is an official account of how a Hornet is launched somewhere. I'll look at the video again to try to understand what you are asking.
As microbrewst points out the Cat O does stuff 'for show'. His actions 'show' that he is checking the cat track fore and aft so that it is clear before final launch signal. Individual Cat Os seem to have variations on 'their dance' how they do things but for sure they all follow a strict protocol so that it is clear to everyone - including the pilot - what is going on. Having seen a few videos of USN launches I would be cackling at some of their antics in the past. Poor guys must get bored. ;D
Perhaps by pointing at the green shirt departing the scene the Cat O is showing that yes he has seen this green shirt and he is getting out of the way. Is that what you mean?
Catapult Launch
http://en.wikipedia.org/wiki/Modern_United_States_Navy_carrier_air_operations
"Hookup Man" ensures that aircraft launchbar (left) and holdback fitting (right) are properly seated in the catapult.
"Catapult hook up is accomplished by placing the aircraft launch bar, which is attached to the front of the aircraft’s nose landing gear, into the catapult shuttle (which is attached to the catapult gear under the flight deck). An additional bar, the holdback, is connected from the rear of the nose landing gear to the carrier deck. The holdback fitting keeps the aircraft from moving forward prior to catapult firing. In final preparation for launch, a series of events happens in rapid succession, indicated by hand/light signals:
The catapult is put into “tension” whereby all the “slack” is taken out of the system with steam.
Simultaneously, the pilot advances the throttles to full (or “military”) power and takes his feet off the brakes. The holdback fitting (mentioned above) keeps the aircraft from moving forward.
The pilot checks engine instruments and “wipes out” (moves) all the control surfaces.
The pilot indicates that he is satisfied that his aircraft is ready for flight by smartly saluting the Catapult Officer. At night, he turns on the aircraft’s exterior lights to indicate he is ready.
During this time, two or more Final Checkers are observing the exterior of the aircraft for proper flight control movement, engine response, panel security and leaks.
Once satisfied, the Checkers give a thumbs up to the Cat Officer.
The Cat Officer makes a final check of catapult settings, wind, etc. and gives the signal to launch.
The catapult operator then pushes a button firing the catapult.
Once the catapult fires, the hold-back breaks free as the shuttle moves rapidly forward, dragging the aircraft by the launch bar. The aircraft accelerates from zero (relative to the carrier deck) to approximately 150 knots in about 2 seconds. There is typically wind (natural or ship motion generated) over the flight deck, giving the aircraft additional lift."
-
He's pointing so that everyone can tell he is indeed checking the areas that he has to before the launch. This way other people (pilot, checkers, cat crew) can all confirm that he did his job.
Also, its actually the Director and not the Cat Officer that gives the pilot the signal to go to military power. He then hands control over to the Cat Officer. 1:16
If there is a need to go into burner, the Cat Officer will give the pilot that signal before launching him. &feature=fvsr 0:16
Thanks for the info on the cat officer never knew what those signals were. but if you look closely at those 2 videos (I've seen them before, no offense) the yellow shirt is wearing kakhi pants which indicates he's an officer and not enlisted. Enlisted (aircraft directors wear camo pants) Officers wear kahki or desert camo. So those 2 are cat officers I don't know why the one with the Tomcat is being directed onto the cat though by an offcier? When really it should be an aircraft director.
-
Close, no cigar! CPO's (Chief Petty Officers) are enlisted, wear khaki's and are directors ;D. But I am impressed with your observation skills.
-
burner12, I'm not understanding your question about the specific Hornet catapult. Probably there is an official account of how a Hornet is launched somewhere. I'll look at the video again to try to understand what you are asking.
As microbrewst points out the Cat O does stuff 'for show'. His actions 'show' that he is checking the cat track fore and aft so that it is clear before final launch signal. Individual Cat Os seem to have variations on 'their dance' how they do things but for sure they all follow a strict protocol so that it is clear to everyone - including the pilot - what is going on. Having seen a few videos of USN launches I would be cackling at some of their antics in the past. Poor guys must get bored. ;D
Perhaps by pointing at the green shirt departing the scene the Cat O is showing that yes he has seen this green shirt and he is getting out of the way. Is that what you mean?
I agree that he is making safety check along the track and I also agree that pointing at the green shirt he has seen the pressure the cat is set at for the correct configuration this shot needs. But I wouldn't say they do it for show it's their job. I was just pointing out that in those 2 videos those are officers not enlisted giving the launch command. Enlisted don't have that authority( and that includes CPOs,they're enlisted) officers do. And I agree they must get bored.
And
-
This site has some good information including animated signallers:
http://navysite.de/cvn/catcom.htm
____________________________
A good story about an E-2 being catapulted:
http://www.neptunuslex.com/Wiki/2007/03/06/event-four/
-
This site has some good information including animated signallers:
http://navysite.de/cvn/catcom.htm
Thanks for the site I'll look at it in detail. Otherwise I think we've arrived at the conclusion that the signals he performs are the following: cat track is clear of FOD and personnel, pointing at the green shirt indicates he sees the pressure is set correctly. Would you agree?
-
Go here (https://www.cnatra.navy.mil/pubs/folder5/T45/P-1212_CH5.PDF) for the T-45 Familiarization FTI from the US Navy. It's full of great tips and Appendix A and B contain the signals from the ground officers.
-
burner12, having looked at the Hornet Catapult video you have referenced at beginning I see the last green shirt near the shuttle for some seconds then he clears the aircraft (possibly at full power by then) with the camera on the Cat O and nothing much else, who does his thing with no one else in sight? Where in the timescale is the 'green shirt' you talk about? Last GreenShirt leaves the shuttle at 1:09. The Cat O waves his hands about later is that what you refer to now? He looks like one of the WIGGLES! (Famous Oz Kiddie Show Characters) ;D
-
burner12, having looked at the Hornet Catapult video you have referenced at beginning I see the last green shirt near the shuttle for some seconds then he clears the aircraft (possibly at full power by then) with the camera on the Cat O and nothing much else, who does his thing with no one else in sight? Where in the timescale is the 'green shirt' you talk about? Last GreenShirt leaves the shuttle at 1:09. The Cat O waves his hands about later is that what you refer to now? He looks like one of the WIGGLES! (Famous Oz Kiddie Show Characters) ;D
He isn't in view in that one try this one, &feature=related at 1:50-1:51 and when he is pointing directly at the aircraft he is signifying what?
You know it's kinda confusing when I look at that file Razgriz suggested fists mean brakes on but whenever I see a launch the aircraft director puts up the fists (brakes on) a green shirt runs from the cat signaling its hooked up and the director moves his torso from side to side. So if fists are brakes on, why have them on when you are about to take off? So what is the correct signal for brakes on and off?
-
Gotcha, in the second Hornet Catapult Video at that time 1:50 the Cat O is acknowledging the salute from the Hornet Pilot that the aircraft is ready to go! (Full Power all checks done). In the first video it looks to me as if the Cat O returns the Pilot salute as a way of acknowledging (if I remember correctly now because I have just seen the TOMCAT launch which is different again).
Anyway to me I recall that in the RAN A4G we were required to salute with the FDO or assistant FDO being the CAT O for the launch (HMAS Melbourne could not simultaneously launch and recover aircraft with the small deck and single catapult). The FDO / CAT O used a signalling flag that was green (or one behind his back in his other hand was RED). He held that RED FLAG out - STILL - if things were not correct. Anyway the FDO would just nod his head imperceptibly to acknowledge the pilot salute during the day time.
Possibly in the first Hornet Launch video the CAT O is saluting back because it is a special event with a special pilot (CAG for example - flying OFF ashore)?
-
Gotcha, in the second Hornet Catapult Video at that time 1:50 the Cat O is acknowledging the salute from the Hornet Pilot that the aircraft is ready to go! (Full Power all checks done). In the first video it looks to me as if the Cat O returns the Pilot salute as a way of acknowledging (if I remember correctly now because I have just seen the TOMCAT launch which is different again).
Anyway to me I recall that in the RAN A4G we were required to salute with the FDO or assistant FDO being the CAT O for the launch (HMAS Melbourne could not simultaneously launch and recover aircraft with the small deck and single catapult). The FDO / CAT O used a signalling flag that was green (or one behind his back in his other hand was RED). He held that RED FLAG out - STILL - if things were not correct. Anyway the FDO would just nod his head imperceptibly to acknowledge the pilot salute during the day time.
Possibly in the first Hornet Launch video the CAT O is saluting back because it is a special event with a special pilot (CAG for example - flying OFF ashore)?
Hmmm, interesting didn't know that about the RAN. If you compare the 2 videos the Tomcat has the Cat O on the port side using his left hand to signal full power, so he can return a right handed salute, but the hornet has the Cat O signaling with his right hand so he (I assume as you said) is acknowledging the pilot by just pointing at him since he is using his right hand to signal full power. You agree?
-
I guess the CAT O has to be able to tap his head with his right hand and rub his stomach with his left hand at the same time to get the job. ;D
Here is a Sinatra ::) Goshawk CarQual Brief PDF zipped made from the original PPT [in colour] (Powerpoint) at:
http://www.wings-of-gold.com/cnatra/CNATRACQBrief.ppt (0.74Mb)
-
From the Goshawk CQ brief above
-
burner12, said: "You know it's kinda confusing when I look at that file Razgriz suggested fists mean brakes on but whenever I see a launch the aircraft director puts up the fists (brakes on) a green shirt runs from the cat signaling its hooked up and the director moves his torso from side to side. So if fists are brakes on, why have them on when you are about to take off? So what is the correct signal for brakes on and off?"
http://www.hnsa.org/doc/pdf/aviationboatswainsmateH.pdf (6.4Mb)
Hand Signal Extracts from above detailed (deck equipment & procedures) document are in the zipped PDF below, with an illustration of one point above (yet to find the 'wiggle' signal).
-
Hey Microbrewst or SpazSinbad when is the launch end speed set for the cat prior to launch is this already past onto the ground crew prior to taxing to the cat or does the pilot pass it via radio before he hooks up?
-
I don't know when the launch weight is passed to the catapult crew but according to Hornet NATOPS: "Catapult Hook-Up. Before taxiing past the [catapult] shuttle, aircraft gross weight should be verified." There is a chap on deck with the weight board. USN personnel should say more about this though.
-
I don't know when the launch weight is passed to the catapult crew but according to Hornet NATOPS: "Catapult Hook-Up. Before taxiing past the [catapult] shuttle, aircraft gross weight should be verified." There is a chap on deck with the weight board. USN personnel should say more about this though.
I'd agree with you Spaz. While the yellow shirt is bringing the plane forward onto alignment with the track a green shirt will have shown him the board at which his plane's weight should be. the pilot, if need be, will correct the green shirt. then while still taxing forward they will pass that info on to the cat operator who will set the catapult pressure for the right weight setting. And I also read that the Cat O has to check the cat settings, so IMO that's why he points at the green shirt. to tell the pilot the cat settings are correct, that it's pressurized to the right amount.
-
Mr. "Spaz,"
I'm glad you have access to all these resources and have posted them here for all to see.
Cheers! ;)
------------------------
Virtuali,
If your reading this, "we" (FSX Users) need ground crew that can do the correct US NAVAL hand signals for the default and Mr. Javier's Nimitz/Eisenhower Carriers as well as on all Military bases. If you can fit that in to any of your developments with a Marshaller, I know it would be greatly appreciated by all. Grazie!
-
Mr. "Spaz,"
I'm glad you have access to all these resources and have posted them here for all to see.
Cheers! ;)
I second that. You have been a big help to us all. Thank you.
------------------------
Virtuali,
If your reading this, "we" (FSX Users) need ground crew that can do the correct US NAVAL hand signals for the default and Mr. Javier's Nimitz/Eisenhower Carriers as well as on all Military bases. If you can fit that in to any of your developments with a Marshaller, I know it would be greatly appreciated by all. Grazie!
-
Virtuali,
If your reading this, "we" (FSX Users) need ground crew that can do the correct US NAVAL hand signals for the default and Mr. Javier's Nimitz/Eisenhower Carriers as well as on all Military bases. If you can fit that in to any of your developments with a Marshaller, I know it would be greatly appreciated by all. Grazie!
+1
I'd buy it if it was payware.
-
burner12, in the instance(s) you point out in videos the Cat O is returning Pilot salute. No one is pointing at greenshirt IMHO. Perhaps at a different time in a different video that may happen; but not in the two Hornet videos you mention IMHO.
-
Once the catapult fires, the hold-back breaks free as the shuttle moves rapidly forward
I'm just curious how the hold back break free, is it some kind of shear pin? Just wondering how the mechanism work.
Jimmy
-
vuong, this online downloadable PDF has most up to date USN deck equipment information: http://www.hnsa.org/doc/pdf/aviationboatswainsmateH.pdf (6.4Mb)
Sadly in this instance it concentrates on the other launch aspects with the holdback not getting much of a mention. However a lot of procedures about deck crew catapulting are explained therein. More later on the holdback details.
______________
From the 'LSO reference manual' PDF: http://server2.simulacion-esp.com/Janes%20FA18/Documentacion/?download=Landing_Signals_Officer.pdf (5.5Mb)
There is this info: "Preparing Aircraft for Launch. The aircraft is spotted just aft of the shuttle at the battery position. After the holdback is installed the aircraft is attached to the shuttle, the bridle tensioner is actuated applying pressure against the grab and moving the shuttle forward to tension the aircraft.
Firing the Catapult. After tensioning, the catapult is fired by opening the launching values and permitting steam to surge into the cylinders. The force of the steam pushes the piston in the cylinder breaking the tension bar. The steam then forces the piston forward, towing the shuttle and aircraft at an ever
increasing speed."
____________________
As you can probably gather I'm more interested in the OLDE SkYhawke so it is easy to reference that info at: http://www.skyhawk.org/specials/html/holdback.htm for HOLDBACK info. I'll look for HORNET specific later.
-
Looks like the catapult system has changed and changed again:
http://en.wikipedia.org/wiki/Aircraft_catapult
"At launch, a release bar holds the aircraft in place as steam pressure builds up, then breaks (or "releases"; older models used a pin that sheared), freeing the piston to pull the aircraft along the deck at high speed. Within about four seconds, aircraft velocity plus apparent wind speed (ship's speed plus "natural" wind) will be sufficient to allow an aircraft to fly away, even after losing one engine."
-
Vuong the answer to your question is a dog bone. The holdback bar has a piece of steel that connects to the back of the landing gear. it's the size of a small dog treat. Half of it is put into the holdback bar and the other half into the landign gear connecting them. Then when the cat fires due to physics the steel breaks straight down the middle of the dog bone, 1/2 staying inside the holdback the other goes along for a wild ride on the planes landing gear.
Watch this video he gives good insight on cat ops,
if you are really anxious then go to 5:12
-
Thank you very much gentlemen.
Jimmy
-
Burner you do your homework dont you. However, the dogbone has been phased out of current carrier ops. Whats used now is called a Repeatable Realease Holdback Bar. The best way to describe it without seeing it is a cork being pulled out of a wine bottle. The cork is the holdback bar and the bottle is the scissor link on the nose gear. The math geniuses figured out how much forward force (thrust) each aircraft can produce, then they made it so the "cork" only comes out of the bottle when more force is created (the catapult pulling the jet). This way nothing breaks, and more importantly..... no FOD.
-
Burner & Microbrewst: This was all news to me also, apparently there are two versions of this 'new' catapult system. See PDF zipped here made from a USN LSO briefing PPT (76Mbs). You can see why there are many pages on one page in zipped PDF to give a sense of what is happening (at under the 1Mb file size limit here). Unfortunately the link to the original PPT file is not available. I'll keep looking. [Pages became scrambled making this sub 1Mb PDF so bear with me - you'll figure it out.]
-
Burner you do your homework dont you. However, the dogbone has been phased out of current carrier ops. Whats used now is called a Repeatable Realease Holdback Bar. The best way to describe it without seeing it is a cork being pulled out of a wine bottle. The cork is the holdback bar and the bottle is the scissor link on the nose gear. The math geniuses figured out how much forward force (thrust) each aircraft can produce, then they made it so the "cork" only comes out of the bottle when more force is created (the catapult pulling the jet). This way nothing breaks, and more importantly..... no FOD.
Yeah here is info on it along w/ a diagram, but it's still the same priciple. 1/2 stays w/ the aircraft the other on the holdback
http://www.freepatentsonline.com/4101099.pdf
-
Actually, the whole thing stays intact and nothing goes along with the aircraft. The point of it was to prevent anything from breaking. It's all based on pressurized release.
-
From another NATOPS: NAVAIR 00-80T-120 'CV Flight/Hangar Deck NATOPS Manual' June 2005
"4.3.3 Determination of Gross Weights
It is essential that the Catapult Officer know the correct gross weight of every aircraft being launched. In order to
minimize any chance of error, the gross weight shall be computed by squadron line personnel/pilot, and shall be
checked by the Catapult Officer against information available on the status board in Flight Deck Control.
4.3.3.1 Weight Chits
1. No later than 45 minutes prior to a launch, each squadron shall furnish the Catapult Officer with a weight chit
listing the computed weight of each aircraft scheduled.
2. Weight chits shall be locally prepared and shall contain the following information:
a. Squadron
b. Date
c. Launch event number or time of scheduled launch
d. Aircraft side number
e. Basic weight
f. Fuel weight
g. Ordnance/external store weight
h. Gross weight
i. Signature of person filling out chit
j. Flap setting for E-2/C-2
k. CRT/MRT for F-14/F/A-18"
&
4.4.2 Confirming Aircraft Gross Weight
As each aircraft approaches the catapult, the Weight Board Operator shall show the pilot/NFO the computed gross
weight of the aircraft. The pilot/NFO shall verify and confirm the gross weight by giving a thumbs-up signal (day)
or a circular motion with a flashlight (night). A thumbs-down or negative signal shall not be used to indicate
disagreement with the weight. If the pilot/NFO does not agree with the gross weight, he shall signal as follows:
1. Day
a. To raise gross weight, hold hand flat with palm up and move in a vertical direction, emphasizing the upward
motion.
b. To lower gross weight, hold hand flat with palm down and move in a horizontal direction.
2. Night
a. To raise gross weight, move flashlight in a vertical direction, emphasizing the upward motion.
b. To lower gross weight, move flashlight in a horizontal direction.
Note
The weight board shall be changed in 500- or 1,000-pound increments in
accordance with applicable launch bulletins.
3. When more than two corrective steps are required on the weight board or any difficulty is experienced in
confirming the gross weight, the aircraft shall not be launched until positive determination can be made by the
Air Officer and confirmed by the pilot and Catapult Officer.
4. Once the weight of the aircraft is confirmed by the pilot/NFO, the Weight Board Operator shall show the weight
board to the Catapult Officer, Centerdeck Operator, and Deckedge Operator (JBD Operator for ICCS).
a. The Centerdeck Operator, Deckedge Operator, or JBD Operator shall in turn relay this weight to the Console
Operator/CCP Operator and Recorder.
b. The Console Operator/CCP Operator shall use this weight in confirming the Catapult Officer’s desired CSV
setting using applicable launch charts.
5. The Weight Board Operator shall display the weight board to the Catapult Officer until he receives a positive
acknowledgement that the weight has been noted.
Note
One weight board is required per catapult. Once the aircraft weight is
confirmed, the weight board operator shall not change the weight displayed
until the aircraft is off the catapult.
-
Actually, the whole thing stays intact and nothing goes along with the aircraft. The point of it was to prevent anything from breaking. It's all based on pressurized release.
Then why in that diagrahm do they show it being split , like a dogbone? Can you tell me the basic way it works? Does it still connect into the back of the LG, and are different bars used for different aircraft?
-
Actually, the whole thing stays intact and nothing goes along with the aircraft. The point of it was to prevent anything from breaking. It's all based on pressurized release.
I've seen this in video I have at home on dvd but don't know of youtube showing it but there must be a youtube video so I'll look and hope someone finds it before me, lol.
-
Perhaps these 'catapult tensioner' graphics from the LSO Catapult briefing PDF explain? Last graphic (4th) is a screenshot from:
"Nuclear Aircraft Carrier Charles de Gaulle (CDG). Focus on the Steam Catapults used to launch the jets. The Steam Catapults technology is originally from Great-Britain but is only operated by USA, France and Brasil (on the Sao Paulo). French catapults are also US tech as the CDG builders thought it would be cheaper to buy the American system instead of developping their own that would do the same job. This vid is about this system and how it works."
-
So your explanation is that the t shaped end fits into the back of the gear then whe launched just falls down and the LG is empty it doesn't break, correct? Are there differetn sizes for different planes or is it universal?
-
The “split” is just a standard schematic drawing technique. It’s used to show that a section of the bar has been removed for the drawing in order to make the schematic fit on the page. In the PDF of the patent, under “Background of the Invention”, read about the 5th paragraph down: “Other holdback bars utilize……”.
If you look it Spaz’s last picture, you can see the holdback in place. The part on the right of the drawing in the PDF is attached to the deck. You can then see the bar is actually much longer than it is in the schematic. The part on the left of the schematic is the part that connects to the back of the nose gear, called the holdback link.
(http://i146.photobucket.com/albums/r275/microbrewst/F-18B_010.jpg)
This is kind of what they look like from the top-down.
(http://i146.photobucket.com/albums/r275/microbrewst/Holdback1.jpg)
(http://i146.photobucket.com/albums/r275/microbrewst/Holdback2.jpg)
The sleeve (which is spring loaded to the forward position) is slid back, and the fitting is placed in the holdback link on the nose gear. The sleeve is then released allowing it to slide forward, holding everything together. When the right amount of pressure is applied, the bar releases the link. Each aircraft does have its own hold back. The sleeves are color coded for each jet.
Spaz, the pictures that you have there are for something a little different. That is referring to taking up the slack in the shuttle once the launch bar is inside of it. Anyone confused yet?
-
No I'm not confused, it seems after seeing holdback bars on the deck they leave the holdback link inside that bar so all they have to do is just slide it to fit into the nose gear. But from the pic you put up of the nose gear what does the end of the holdback link (the part that attaches to the plane) look like? To me from the pic it looks like a T that fits inside that slot on the LG, then when fired just drops down. Am I not correct?
Question where are you finding these pictures, i did a search and found nothing but that PDF file.
-
The holdback link itself is part of the plane, the nosegear to be more accurate. It is the little thing in the first pic that sticks out from the back of the nose gear. It kind of looks like a giant electrical plug, or clamp.
-
microbrewst, definitely I had no idea about this new arrangement for catapulting. No wonder I'm confused. ::) It helps to have / use the new correct terminology as indicated. That will help searching for info on the net. Thanks for the illustrations - they really help get the picture.
-
The holdback link itself is part of the plane, the nosegear to be more accurate. It is the little thing in the first pic that sticks out from the back of the nose gear. It kind of looks like a giant electrical plug, or clamp.
You know from seeing this image it seems that the clamp on the back end of the gear is put inside the holdback link and then when fired the link drops down and the LG is released from the plane.
(http://upload.wikimedia.org/wikipedia/commons/6/64/US_Navy_020816-N-6268K-002_Sailor_checks_the_launch_bar_of_a_F-A-18.jpg)
And why do they need to have the ability to slide it, if they use different ones for different planes? When would a plane be at a different elevation?
-
You know from seeing this image it seems that the clamp on the back end of the gear is put inside the holdback link and then when fired the link drops down and the LG is released from the plane.
Dont confuse the terminology. The holdback BAR and the holback LINK are two completely separate things. The clamp IS the holdback LINK. It is part of the nose gear and is what they connect the holdback BAR to. The holdback bar then connects to the deck and keeps the jet in place.
As for the sleeve, think about a jigsaw puzzle piece. Because of the shape, the only way to fit one piece into another piece is to lay it over top and push down on it. That is the same way the bar is connected to the link. If the sleeve couldn't retract, you couldn't put the fitting from the bar into the link. Then the sleeve goes over the connection to hold it all together.
-
Hi Microbrewst,
What make the holdback bar drop down so easily when it is under tremendous tension?
Jimmy
-
vuong, this does not answer your question because I don't know but it comes from NATOPS, perhaps Googling question might bring up some answers. Having the correct terminology is important so here the NATOPS description is useful:
F/A-18A/B/C/D NATOPS
Catapult Hook-Up. Before taxiing past the shuttle, aircraft gross weight should be verified, takeoff checklist complete, and arming completed by the ordnance crew if required.
Check external fuel quantity. Approach the catapult track slowly, lightly riding the brakes, with
nosewheel steering on. Use minimum power required to keep the aircraft rolling. Close attention
to the plane director’s signals is required to align the aircraft with the catapult track entry
wye.When aligned, the plane director signals the pilot to lower the launch bar. Place the launch
bar switch to EXTEND. The green LAUNCH BAR advisory light comes on and nosewheel
steering disengages. Nosewheel steering low mode may be engaged while the launch bar is
down by pressing and holding the nosewheel steering button. This should only be done on
signal from the director since catapult personnel may be in close proximity to the launch bar. Do
not use nosewheel steering once the launch bar enters the track. The catapult crew installs the
holdback bar and the aircraft may taxi forward slowly, following the signals of the plane director.
When the launch bar drops over the shuttle spreader, the aircraft will be stopped by the
holdback bar engaging the catapult buffer. On aircraft 161353 THRU 161715, upon receipt of
the “Release Brakes” signal, advance throttles to 85% to 90% rpm. Do not advance throttles to
MIL at this time since this could retract the launch bar before it is trapped by the tensioned
shuttle spreader. On aircraft 161716 AND UP, upon receipt of the “Release Brakes” signal, advance throttles to MIL.
___________________________
8.2.8 Catapult Launch
WARNING
Do not catapult with partially full external fuel tank(s).
When the “Final Turnup” signal is received from the catapult officer, advance throttles to MIL or MAX. On aircraft 161353 THRU 161715, the launch bar switch automatically returns to RETRACT and the green LAUNCH BAR advisory light goes out. On aircraft 161716 AND UP, place the launch bar switch to RETRACT. Cycle the flight controls, wait 4 seconds then ensure all warning and caution lights are out. If afterburners are to be used, select them on signal from the catapult officer. Check engine instruments. When satisfied that the aircraft is ready for launch, hold throttles firmly against the detent, place the head against the head-rest, and salute the catapult officer with the right hand.
WARNING
• The close proximity of the Flap and Launch Bar switches may result in inadvertent selection of FLAPS UP vice launch bar up.
• Movement of the Launch Bar switch to RETRACT prior to the aircraft being fully tensioned may result in a mispositioned launch bar and subsequent launch bar/shuttle separation during catapult launch.
NOTE
Failure to place launch bar switch to retract may result in hydraulic seal failure.
-
FWIW: http://safetycenter.navy.mil/media/approach/vault/articles/2004/0772.htm
Holdback Fitting Failure by Lt. Adam J. Smith/FA-18
After four weeks of operations off the coast of Florida and in the Gulf of Mexico, the CVW-17/JFK team was almost complete with COMPTUEX. As anyone who has ever been involved in the normal CV workup cycle knows, most squadrons run a heavy schedule during COMPTUEX, and VFA-83 was no exception.
On 14 March 2004, our squadron had 23 sorties and 9 alerts scheduled. I was one of the lucky ones programmed for a 1.5-hour cycle DCA (day trap variety) with four hours of Alert-7 to follow. The flight brief was short and to the point. I was to fly with the squadron Operations Officer as his wingman. I walked to the jet and conducted my regular preflight inspection. The startup and subsequent taxi to the catapult were routine. What happened next was anything but ordinary.
I taxied onto catapult #3 in the usual fashion. Everything seemed normal as the aircraft entered the catapult track. The holdback fitting was attached, and I was armed up by the ordnancemen. The taxi director stood on my right side between the tower and the cat as he gave me the "take tension" sign. Following the control surface wipeout, I performed a last minute check of the flap and trim settings, the radalt bug and the beer cans (wing spread and locked indicators). With all of the take-off checks completed, I saluted the catapult officer.
As the Catapult Officer returned my salute, I positioned my left hand on the throttle and my right hand on the canopy bow handle (towel rack). Looking down the catapult track, I kept the green shirt that was going to press the catapult-firing button in my peripheral vision. I felt the holdback fitting release as the button was pushed; however, the sensation of the normal catapult acceleration was absent. I instantly knew that I had suffered either a "cold cat" or hold back fitting failure. Selecting ground idle with both throttles, I threw the arresting hook down and stood on the break pedals as if my life depended upon it. My Hornet stopped accelerating down the cat track, but it was still sliding towards the forward edge of the deck. In a final attempt to stop before pulling the ejection handle, I drove the right rudder pedal down in an effort to ground loop the aircraft. The jet rotated 90 degrees to the right and continued to skid down the angle. I was now staring straight at aircraft 310 on Cat #2 with both main mounts stuck in the greasy cat track offering no friction whatsoever. The aircraft finally came to rest with the port main mount a mere 15 ft from the deck edge, and I was looking at nothing but water under my left wingtip.
Although I had not initiated any communication with the tower during the entire incident, I did recall hearing someone transmit over tower frequency and say, "get the Hornet." It turned out this was the Skipper of our EA-6B squadron who was witnessing me slide forward on the LA.
Immediately after the incident, both the Ship's Safety Officer and the CAG Safety Officer took a vested interest in getting to the root cause of the narrowly averted mishap. As my squadron maintainers scrambled to examine the holdback fitting that is attached to the nose gear, the ship folks examined the holdback bar.
The F/A-18 uses what is called a "Repeatable Release Holdback Bar (RRHB)." These bars are taken to AIMD and inspected after every 100 traps to verify the integrity of the bar. The preliminary investigation report pointed to a failure of the RRHB that caused it to only partially reset in the deck plate and therefore fail during my launch. Subsequent investigations by the Air Division showed that the ship had more RHHBs in the same unsatisfactory condition. Since the incident, all of the RHHBs have been inspected, and the failed RHHBs have been replaced. In an additional measure, the "shooters" now incorporate a more stringent examination of the RHHB as part of their prelaunch checklist.
In conclusion, the normal safety procedures that F/A-18 aircrew have in place, including emergency procedures review before each and every flight, worked and kept me and aircraft 301 in one piece.
Lt. Smith flies with VFA-83.
-
Hi Microbrewst,
What make the holdback bar drop down so easily when it is under tremendous tension?
Jimmy
I'm kind of confused by your question. I guess the best way to clarify is to ask you what you would expect it to do.
-
Hi,
I believed I got the answer from your previous tread:
"Actually, the whole thing stays intact and nothing goes along with the aircraft. The point of it was to prevent anything from breaking. It's all based on pressurized release."
Thank you very much
-
Good pics and general info here:
http://en.wikipedia.org/wiki/Modern_United_States_Navy_carrier_air_operations