Forum: General F-35 Forum

It's a tad premature to imagine the C gets cancelled before knowing what the fix is, how much that costs, etc. In budget terms cancelling the C means raising the cost of the other versions while taking money out of the program to purchase more F/A-18E/F's and making development of the NGAD (F/A-XX) a higher priority along with the production UCAS-D (X-47B). Also the C doesn't just have one customer. If getting it to trap takes a significant redesign the better bet might be on them doing that.

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Lampshade..... Much of what you see on the F-35 fourm of F-16.net is just speculation and conjecture, aka kicking the ball around in hopes we can figure out the secrets of the F-35.

The problem with tail hook is it's as far back as Lockheed Martin could get it and still be contained in a stealthy fairing. As for the F-35's stealth coatings they are different then the F-22's. The speculation about the F-35 coatings relates to the conjecture of what limits the F-35's ultimate top speed to mach 1.6 +, whether it be the airframe limited (dynamic pressure), air intake limited, or limited by the thermo stability of its ram coatings.

Here is a picture of the tail hook fairing door missing and with I think tail hook removed. ***or not!***

http://farm8.staticflickr.com/7145/6441372109_8ace97c8fd_o.jpg

Here is a picture of the tail hook in flight.

http://www.youtube.com/watch?v=XQyf2jeElyg

See the 3:08 mark.

Look at the hook profile? It looks like it wouldn't fish never mind a three wire. Definitly needs to be reprofiled "I think".

Looking at how the F-35C touches down, I think once they get the proper hook profile, correct damping, and angle on the tail hook they should be okay.

http://farm2.staticflickr.com/1196/4722234530_fedb9c8890_o.jpg

Last edited by spazsinbad on Dec 16, 2011 - 11:52 PM; edited 4 times in total

alloycowboy, thanks for the links. Have not seen the F-35C wingfold in motion before. Not exactly a good angle below and behind to see the hook in relation to main gear in the 'better than nothing' screenshot.

[edit] It has occurred to me since reading the Tommy H. Thomason post about tailhook design that the screenshot shown below has the F-35C 'getting dirty' (lowering wheels, flaps & hook) at probably the maximun allowed airspeed so the angle of attack will be lower than the more nose high Optimum Angle of Attack used during a carrier approach). So we see the hook tip 'higher' than usual compared to main wheels due to the flat attitude at much higher airspeed.

People.. Do not fall into the same trap as many of the F-35 detractors have by digging the trenches even deeper. Clearly this report would bring a lot of concern to the program for a lot of people. I surely hope that the program partners were given this info BEFORE this report was leaked. If not, the program partners have to question a lot of things from this point onward.

Being an F-35 advocate myself, I have to admit that I was quite floored when I read it. Also, IF Sweetman is correct in his assertion about the classified problem being stealth characteristics; this gives all the more reason to be worried. Stealth is one of the main reasons for buying this jet. Even lack of maneuverability is mentioned in the report several times, a factor many maybe have tolerated somewhat because of the significance of stealth and DAS, etc.

If the program is slowed more than it already is, I fear Norwegian politicians may be forced to look for alternatives. Our F-16's are the oldest flying in the world, and a lot of them are probably not airworthy. I’ve read that LM had to open a new production line for some new wings, because the newer generations of wings don’t fit our old aircraft. The time is running out.

A little perspective for those of you who might not know. At the link below, GAO Report on F/A-18 E/F EMD Progress from 1999. "Super" Hornet came out of OT-IIB with 29 Major Deficiencies. They went into OPEVAL with 84 deficiencies, 71 of which were not corrected until after OPEVAL. The correction of many of these discrepancies, including structural fixes at 2000, 4000 and 6000 hours continues even today, 12 years later. And many are beating up F-35 for how many issues in the QLR?? Get a grip on yourselves.

What we see playing out in the media and across on the internet about F-35 is all about politics, inter-service battles over budgets and service priorities, and corporate competition in the aerospace sector. It has been going on for roughly two years and will get even more intense as we go forward.

http://www.gao.gov/archive/1999/ns99127.pdf

alloycowboy wrote:

@arkadyrenko.... The speculation about the A4 tailhook was just kicking the ball around trying to figure what Lockheed Martin is upto with the F-35C. Given the level of CAD and virtual reality that Lockheed Martin employed I just can't see the tailhook not working. You have to remeber these are the guys that got the F-117 to fly. If anyone can do it is Skunk Works. If Skunk Works can't get it to work then it can't be done!

I think we are finding that the design tools that LM thought were going to foster concurrency and somewhat shorten development are turning out to be less accurate than initially thought. The tailhook issue is serious, but the design for the -C has been available for review for a while now, and nobody (at least publicly) raised a concern about its placement.

Oldie but goodie F-35C hook pics from [& reposting an oldie from elsewhere - an old LSO newsletter I think?]:

Arresting F-35s & Brake Testing

http://www.f-16.net/f-16_forum_viewtopi ... -hook.html

http://attach.high-g.net/attachments/f3 ... en_194.jpg
http://www.jsf.mil/images/gallery/sdd/f ... tc_002.jpg
http://www.jsf.mil/images/gallery/sdd/f ... tc_007.jpg

Adm Roughead may live to regret the photo of him autographing the tailhook....

The Navy would be out of JSF 'tomorrow' if they could kill STOVL and avoid leaving any DNA on the murder weapon or the crime scene.

'quicksilver' I'm interested to know how you can be a spokesperson for the entire USN when USN support for the F-35 series has been stated over and over again?

Last edited by cxxtxx on Dec 15, 2011 - 11:55 PM; edited 1 time in total

It's hard to image the amount of force, kinetic energy, that would be required to scuff, much less break, that tailhook. Wow-o-wow, talk about solid and robust. The linear actuator looks like it could lift a bus. That setup would trap a 747.

Is it steel or titanium?

I'm not trying to be over-overly critical, but if every system and subsystem in the aircraft is designed like that, it's no wonder why they are having trouble with weight.

Chad

@Cxxtxx...... Who said the tail hook broke?

alloycowboy wrote:

@Cxxtxx...... Who said the tail hook broke?

Nobody, and believe me, nobody is EVER going to break it. That's a serious piece of equipment.

Chad

Chad, the F-35C entire airframe substructure is especially strengthened to take the forces of catapulting and arresting. That is the nature of Naval Aircraft. Some hooks have proved stronger than others over the years and perhaps needed to be changed early on. From memory that 'short' A-4 hook weighs over 60lbs - might even be 100lbs - I'd have to look that up though to be accurate. The A-4 hook could be 'sharpened' to keep it catching a wire but probably made it more prone to damage a wire if the hook point impacted on top of the wire. However wires are inspected after each arrest for such damage AFAIK.

Other threads on this forum recently have described the USN arrest/catapult systems and forces. The hook lifting/damper mechanism is strong especially to stop the hook bouncing on the steal deck. Hook skips can cause the hook to bounce over the wires for a bolter. If that mechanism fails the hook will fall down under its own weight as a safety backup via mechanical linkage and this is likely the case with the F-35C but I don't categorical know that - just a guess.

Chad you seem to like to make overly categorical statements about issues. Yes hooks can break; especially at the attachment point. This seques into a nice story about the first A4G lost due engine failure out to sea near the main RAAF fighter base at that time Williamtown. Many years later a trawler net brought up some items of wreckage, among them being the hook - intact - all the rest was rubbish of course. Pilot ejected safely at 10k or thereabouts, with engine disintegrating, according to wingman.

I hope Chad you can see (from the photos on this page) the height difference between an T/A-4 and an F-35c HOOK attachment point. [Chad stated on previous page of this thread: "But it’s not just the difference of 2.3 linear feet between the A-4 and F-35 C, (not to mention the extra five to eight tons slamming down on the deck,) it’s the actual geometry of the arresting gear. The attachment point of the F-35C arresting gear is significantly higher off the deck than the A-4, AND it’s 2.3 linear feet shorter behind the landing gear, therefore the downward angle of the arresting gear has to be much steeper. Just from looking at it, I can't see how it’s ever going to work on an operational flight deck. I just don’t see it...."]

Here is what a 'hookman' or 'hook runner' (in RAN FAA) had to do sometimes although usually a combination of allowing the aircraft to be 'towed backwards' momentarily and then hitting the brakes would cause the wire to drop out of the hook mouth. If not the hook guy is right there to manually do it often with help. It is important to get the aircraft out of the landing area pronto.

http://a4skyhawk.org/content/148607-va- ... entry-2118

http://www.a4skyhawk.org/sites/a4skyhaw ... 148607.jpg

Last edited by spazsinbad on Dec 16, 2011 - 12:51 AM; edited 3 times in total

A concise overview of naval aircraft requirements is here. However this forum has a tonne of information about the F-35C specific requirements:

Carrier Design

http://www.globalsecurity.org/military/ ... design.htm

"...The design of naval aircraft starts with the airframe and landing gear, as they must withstand a tremendous shock each time the aircraft launches or lands. Each carrier-based aircraft has a tailhook, a hook bolted to an 8-foot bar extending from the after part of the aircraft. It is with the tailhook that the pilot catches one of the four steel arresting cables stretched across the deck, bringing the plane to a complete stop. The cables are set to stop each aircraft at the same place on the deck, regardless of the size or weight of the plane. Four 1.375-inch-thick steel cables run 2-5 inches above the deck at 35-40 foot intervals and connect with a hydraulic cylinder below the deck, which services as a giant shock absorber. As an aircraft approaches, all four wires are set to accommodate that aircraft's weight. When the aircraft's arresting hook snags a wire, the wire pulls a piston within a fluid-filled chamber. As the piston is drawn down the cylinder, hydraulic fluid is forced through the small holes in the cylinder end, thus absorbing the energy of the aircraft and braking it to a stop. An arresting wire can stop a 54,000-pound aircraft traveling at a speed of 130-150 miles per hour in a distance less than 350 feet. When the aircraft drops the wire, the piston is retracted and made ready to recover another aircraft in 45 seconds...."
__________

Another place to visit would be here: http://science.howstuffworks.com/aircraft-carrier4.htm

"...The arresting wires are stretched across the deck and are attached on both ends to hydraulic cylinders below deck. If the tailhook snags an arresting wire, it pulls the wire out, and the hydraulic cylinder system absorbs the energy to bring the plane to a stop. The arresting wire system can stop a 54,000-pound aircraft travelling 150 miles per hour in only two seconds, in a 315-foot landing area (a 24,500-kg aircraft travelling at 241 kph in a 96-meter landing area).

There are four parallel arresting wires, spaced about 50 feet (15 meters) apart, to expand the target area for the pilot. Pilots are aiming for the third wire, as it's the safest and most effective target. They never shoot for the first wire because it's dangerously close to the edge of deck. If they come in too low on the first wire, they could easily crash into the stern of the ship. It's acceptable to snag the second or fourth wire,..."

Pic Caption at same web page:
"The tailhook of a KA-6D Intruder aircraft, about to catch an arresting wire on the USS Dwight D. Eisenhower | Photo courtesy U.S Department of Defense

http://static.ddmcdn.com/gif/aircraft-carrier-58.jpg

Forum: General F-35 Forum

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