Carrier landings Decceleration & Pilots Head
 

Carrier landings Deacceleration approach at 160-180Knots ? or slower
Short Distance from arrestor to stop 100 metres ???
Questions
Approach speed ?
Deacceleration Distance ?
Forces on Deacceleration ?
What happens to the pilots head with a Heavy Helmet on is it restrained does it dip forward and down or can neck muscles control or restrain it ?????

Thanks

I don't know the exact answer but don't forget to subtract the forward speed of the boat and any wind over the deck. That makes impact speed a little more palatable but still pretty violent.

BV

All this recent research finding long term brain damage in American footballers, soccer players and boxers from the brain banging around in the skull; then you look at the forces exerted on a catapult and by a cable arrest.

Explains a lot - though not Sharky......

Out of interest, how different is a carrier's cable run out and deceleration force as compared with, say, taking the approach end aerodrome RHAG in an F-4?

I didn't find RHAG engagements particularly severe - but what was it like taking a wire on the Ark Royal in an FG1 back in the days when the UK could afford real carriers?

TJ,

Perhaps I can help a bit.

Approach air speed will be around 150 knots. Actual 'trap speed', when the aircraft engages the arresting wires, will be reduced by the Wind Over Deck (WOD) generated by the carrier's speed through the water. I believe, (but am happy to be corrected) that maximum 'trap speed' is around 150 knots, but that they usually aim for around 130 to reduce wear and tear on the wires. I could be wrong on the figures here though.

Yes, deceleration distance is around 100 metres.

Forces - that's where i have to admit lack of detailed knowledge - these will depend on the time/distance/ force schedule of the arresting engines (the large hydraulic engines below decks that allow the arresting wires to pay out, all the while applying the braking force). The scheduling of the arresting engines is adjusted not only for the type of aircraft, but (I believe) also for the weight of the aircraft as they trap. A heavier aircraft needs more force to bring it to a halt before it falls off the deck, but a less strong aircraft (say an AEW aircraft) can't sustain as much retardation force through the hook system as, say, a fighter.

Your question about heavy helmets is a good one. A the weight of helmets has increased, especially on the F-35, I am sure that the USN Navair community will have been providing very detailed guidance and instruction on how hard the aircraft can be arrested without the pilot having excessive strain placed on his neck, shoulder and upper back.

Hope this helps, best regards as ever to all those good Navair people solving those hard naval aviation issues,

Engines

Thanks 'Engines' I'll guess you were thinking about the F-35C with your reply. 'Sharkey' Ward flew the RN F-4 before transitioning to the Hairier AFAIK. Two A4G videos in slow motion - particularly the 'arrest' show how the pilot reacts to the forces being applied. In this case the A4G can be in a range of KIAS (depending on aircraft weight at Optimum Angle of Attack) whilst decelerating on arrest in less than 300 feet (the last wire No.6 from Sea Venom/Gannet era of HMAS Melbourne was removed for A4G/S2E/G because there was not enough room for arrest).

True story: An A4G pilot - not me - arrested onboard at least twice when NOT 'harness locked'. Luckily helmet visor was down preventing face injury as it hit the gunsight with force. Why was this so? A long story indeed.

IIRC USN pilots mention 3-4 lateral G for their catapulting these days down the approx. 300 foot cat track to get to flying speed at usual launch weights. VX-23 test pilots ashore using land catapults go up to 6G during testing they claim IIRC. A4G pilots rattled down the 100 foot track at 6G regularly - it is as though one is THUMPED in the chest by a closed fist with all the power one can stand - in less than two seconds.

Regarding an A4G arrest at wheelspeed of say 100 knots to zero in say 275 feet I would comment the first one was just bewildering indeed. It is nothing like a land arrest on a runway short field arrest with some 1,000 feet of run out to stop. My first arrest was followed by first catapult which is always followed by a send home for newbies because how much can a KOALA BEAR in one day. :} For sprog pilots such as meself this was my first arrest and catapult ever (poorly trained by RAAF crabs initially for carrier aviation). :}

Catapult pilots have their heads back against the ejection seat headrest in preparation for the launch so in the case of the A4G there is no head movement. In videos we see the heads of the USN jet people bobbing up and down initially (which is an issue for the F-35C at moment when aircraft at light launch weights such as for CarQual).

Graphic from A-4E/F/G NATOPS shows relationship between Skyhawk weight and Optimum Angle of Attack airspeed for an arrested carrier approach. The MELBOURNE LSO Notes show Maximum Engage Wheelspeed for the A4G to be 107 Knots. If one follows 'Engines' explanation then Approach KIAS at a specific allowed weight with a specific WOD may be deduced. The red lines/circles show the max. arrested landing weight of 14,500 lbs with Opt AoA airspeed of 128 so if the max arrest wheelspeed is 107 then the WOD (combined ship speed [which MELBOURNE could achieve max 21 knots] and wind speed down the angle deck should be more than eleven knots. There would be a buffer for sudden reductions in wind speed. MELBOURNE at 21 knots was a sight to behold & experience - the shaking - oh the horror. :}

http://i98.photobucket.com/albums/l2...t.gif~original

A4G Arrest HMAS Melbourne & Hook Runner Slow Motion


SLOW MOTION Catapults A4Gs 886 & 889

From Engines post and assuming a constant deceleration

v^2=u^2+2as

130 knots is approx 66.9 m/s
distance is 100m, so deceleration is 22 (ish) m/s^2

which is 2.3g. (Various bits of rounding there).

Now I know nothing about the profiles of the arrest, but I would have thought a constant deceleration gives the minimum as any non-linear piece would (I think) imply greater deceleration at another time point.

Formulae may indicate approximations of the forces felt during an arrest and catapult however the steam catapult applies more force in first stage of launch compared to later stage. EMALS will even out these forces to create less stress for all concerned. Similarly the Advanced Arrestor Gear (AAG) will even out the arresting force for all users.

In the video below CMDR Clark describes his first A4G arrest/catapult. In mid 1960s when the RAN FAA was regenerating fixed wing ops he was trained in USN with a bunch of others so he has arrests and free deck launches in the Trojan T-28C. Subsequently he went to Vietnam with the Iroquois RANHFV (hence 'shot at' references). Upon return he transitioned to the A4G Skyhawks (other pilots similarly did same). He says "under two seconds' which is clipped out in the poor quality video. In second video LCDR Ward USN famously exclaimed "HOLY SHI T!" after his first A-4B catapult (demo) from HMAS Melbourne mid 1965.

Clark A4G Skyhawk 1st Arrest & Catapult HMAS Melbourne

Google HAN's device...

https://en.m.wikipedia.org/wiki/HANS_device

"A major cause of death amongst drivers during races was through violent head movements, where the body remains in place because of the seat belts but the momentum keeps the head moving forwards, causing a basilar skull fracture resulting in serious injury or immediate death.

Notable race car drivers who died from basilar skull fractures include:

Formula 1 driver Roland Ratzenberger [3] in the 1994 San Marino Formula One Grand Prix. (Ayrton Senna also sustained a basilar skull fracture that might have been lethal in this Grand Prix, but the official cause of death was brain penetration by shrapnel[citation needed])
Indy 500 drivers Scott Brayton, Bill Vukovich and Tony Bettenhausen
NASCAR drivers Adam Petty, Tony Roper; Kenny Irwin, Jr.; Terry Schoonover, Grant Adcox, Neil Bonnett, John Nemechek, Dale Earnhardt, J. D. McDuffie, and Clifford Allison
ARCA driver Blaise Alexander
CART drivers Jovy Marcelo and Gonzalo Rodríguez"

Racing Car Drivers Dead in Race Car Crashes - wut? Famously (or not) carrier landing arrests are described by the MEEDJA as 'controlled crashes' - emphasis is on CONTROL! Here are some more examples from MELBOURNE in 1976. I'll RESTRAIN MEself. At end Helo view is from a plane guard Sea King I'll imagine.

1976 HMAS Melbourne Fixed Wing Carrier Qualification

maybe they could use this on the f35 helmet?

https://en.wikipedia.org/wiki/HANS_device

:} Oh well... we can't keep a good F-35C thread down eh. Already there are 'concerned' criticisms about 'look back' in the F-35 cockpit (solved by Norsk pilot saying "lean forward then look back"). Wonder you didn't mention air bags - I guess - for the arrest. The F-35 ejection seat system has a similar 'blow up' HANS helmet restraint during ejection. One can watch a long or short version of a Martin-Baker Slow Motion F-35 ejection seat video or perhaps a screen shot'll do. Dunno. My fav slomo is this one. start at if bored: https://youtu.be/DbQuaG4NfN8?t=255 4min15sec

AFAIK no NavAv pilot has complained about arresting forces - they are grateful - NavAvers/Birdies are a tuff breed. :}

http://i98.photobucket.com/albums/l2...t.jpg~original

IIRC, the standard RN cat stroke was 100ft/1second: Ark's two cats were 180ft and 200ft, so about 2 seconds was right. The Melbourne cat certainly looks a tad shorter, I'd be interested to know just what length it was?

I only scored a night back seat ride in a Gannet AEW3 off the Ark, it seemed quite sedate after catching the wire. Nearly woke me up :cool:

(XL500, complete with Charlie's plaque in the back!)



All this talk reminds me how much better it is to stop, then land, when recovering on a Grey Funnel Liner :ok:

John.

My memory is poor, and I have no documentation to refer to, but I seem to remember the cat shot on the Melbourne was around 93 feet. A very (!) short run to get our end speed.

The shortest deck run in the Sea Harrier was 200 feet (i.e. just at the start of the ramp), and recall thinking how ridiculous half that distance was, for double the end speed!

Spazzo, it was worth watching the whole video just for the Inna Gadda da Vida backing track!

'OK4wire' has a good memory but like a piece of string - it all depends. In the Sea Venom / Gannet era the catapult stroke length was reportedly 90 feet. The Venom was limited to about 4.5 lateral G for catapulting so was limited in hot conditions, nil wind in the tropics (a familiar refrain perhaps hence SRVLs for the BeeBabies). The A4G Skyhawk was not so limited with a 9 lateral G limitation. It was said a 'warshot' could fling the A4G at max weight 24,500 lbs under any conditions except HADES. However CHLOE would have been the only bit of metal to undergo such torture.

After collision with USS Frank E. Evans in 1969 the repaired bow included a 'bridle catcher' with provision to lengthen the catapult by some ten feet. How much stroke length that meant has never been clear. Anyway by 1970-71 the actual stroke length was increased to 100 feet - some say 105 feet - with parts from HMCS Bonaventure. And I guess we can take that as stroke length. I can recall being told the catapult stroke was 100 feet long late 1971 early 1972. The slow motion film of catapulting the A4G was to see how the 'bridle catcher' was working. Centreline stores would have the fin removed so that the 'catcher wire' would not interfere with it. Aboard USS Kearsage [a wood decker] in 1969 when cross decking our one and only buddy refuel tank at that time was damaged by the arrangement of the 'bridle catcher'.

'Ascend Charlie' (is it not TIME? :-) ] There is another slightly less long with my actual favourite of favourite track of sound - especially appropriate at the end:

F-35 MB US16E Ejection Seat Tests 1-8 Slow Motion Long Play 10min 18sec

USS KEARSARGE CV-33 with Hydraulic Catapults & WOODEN DECK
From Dutchy Brauer - HMAS Melbourne/USS Kearsarge 'Crossdeck operation '69

Much talk of pilots' heads on this thread.

Dont forget, in F4's and the like there is/was the observer's/navigator's head to consider as well

Or don't they count? ;)

I believe it's the larger size of the pilots' which is of concern.....

Your mention of the 1969 collision flagged up the memory of 2 of Melbourne's A4s taking up temporary residence at Tengah. Lovely-looking aircraft, IMO.

.

To answer BEagles question, Arresting Systems on Carriers can be set for specific aircraft types and weight. The RHAG was not adjustable so a much lighter aircraft than the Phantom may feel a bit harsher on the Pilot and in some aircraft, the F5 for example approach end engagements were not permitted. The BAK 12 Arresting System is adjustable but it would generally take an hour to adjust it which is of course not acceptable so it is generally set for the heaviest aircraft. The first couple of Typhoons arrested here were quite fast and the Pilots certainly fealt it. There are some new systems on trial at the moment that will sense the force and apply the appropriate brake pressure to smoothly stop the aircraft.

Thanks for photos 'MPN11'. A4G Side Number 889 was lost to a cold catapult a few years later with the pilot escaping under water after carrier passed by. 887 still flies today with DRAKEN USA as N144EM. Recent photo:

https://www.flickr.com/photos/eor1/28295842072/

'OK4Wire' said: "...I have no documentation to refer to...". If one navigates to: SpazSinbad A4G | Fleet Air Arm Association of Australia then following directions there, one may download all kinds of information about Naval Aviation for future reference. RAF CRABS should not bother - mainly because one of note here earlier said 'it was all gibberish'. However if directions followed perhaps there will be less of that. 50 years ago 'OK4Wire' featured in a hangar fire. BZ.

For 'MPN11' RAF Hawker Hunter FGA.9 — serial XG153 of 20 Sqn June 1969 & 887 & 889

http://i98.photobucket.com/albums/l2...m.gif~original

BEagle, the run-out on a RHAG is around 1300ft, so about 4 times the run-out of a carrier trap wire.

If memory serves: Typical max trap weight for the F-4K (and Bucc, curiously) was around 37,000lb. At that weight the F-4K's 19 units gave 137kts, which equated to around 111kts relative if all was well with the ship. Single engine (half flap) landings were around 8-10kts faster and the ship, if able, tried to help with extra wind over the deck. If not, you might have to reduce your weight further.
Bruise marks from the shoulder straps were the most noticeable physiological effect.
Many wore either a Formfit or the good old Mk1 to reduce neck strain as, with with your head on the headrest, it was almost impossible to watch the ADI attitude during the shot.

Nice pic Spaz...

I thought the title of this thread meant it was about sliding off the end of dining room tables when pissed after dinner and the loyal toast.

Nice exchange of photos there, SpazSinbad :)

I remember being in Tengah Local, with 2 pairs taking off in trail ... the Hunters went first followed by the A4s. The A4s were airborne first :)

Coukd it even have been that sortie? :)

'MPN11' after just starting at NAS Nowra, after being in the RAAF for fifteen months doing ground school then basic / advanced flying training, it was a shock to hear about the collision. And I now cannot remember the source of that photo. Usually my attempt is to keep those details these days, so it must have been an early addition to the now 12,300 PDF pages maxing out at 4.4Gb to fit on an archive DVD available for download - see above details. Those pages include heaps of info about 'how to deck land' down through the ages with a bunch of stuff I had no idea about in that prehistoric information age.

'MinnieBurner' said above: "...Bruise marks from the shoulder straps were the most noticeable physiological effect...." That was my permanent state - I was strapped in as tight as possible at all times (especially in the Macchi MB326H which had a forward lean in the seat but only a shore based trainer jet). Once on advice from a more experienced but relative peer, I put my A4G seat full down for the catapult shot so that a good view of the instrument panel was obtained (for impending night cat shots). Usually I flew at all times with seat as high as it could go. BIG MISTAKE - even on night shots I launched with the seat full up however the ABBAJABBA (artificial horizon) was easily visible - it was a great bit of kit.

Regarding helmet effects during arrest onboard - not noticeable in the horrendous :} - but very welcome stopping forces. After that first one - no problemo.

F4 landing on Ark Royal
 

I flew F4's to the deck for some years.
Approach speed about 132 kts.
Speed over round down 102 kts relative
250' of roll out progressively increasing deceleration.
No significant head problems since it was all anticipated.
Occasional marks from shoulder straps.
Good fun

Ok3W here. Sinbad, my memory is a 97 ft stroke with another 8 feet for the deceleration spike. Total of 107 ft. I endured just one warshot at 6g and about 19500 lb. It was requested to functionally check a new nose-mechanical fuse for Mk 82's. The airplane soared off the cat, but I greyed out, and the fuses worked.

Unlike others of the class the cat track was never moved and was limited by the forward lift well.

I always kept my seat as high as possible, but could still see the Abberjabber on the cat ride. First move after flaps up was to release the harness lock, which stayed loose until downwind.

One of my colleagues forgot to relock the harness, and the arrest caused him to smash the visor assembly on the gunsight. No one knows the decel G, but if you zeroed the g meter, it allegedly read 4.5 at the end of the pullout.

Ok3W (the hangar fire escapee)

'Three Wire' many appy polly loggies. Thought you may have changed your LogOn. So WHOis the other chap? Dunno. Notice how the date was comfumbled? Just for disfusion.

I have a few quotes via e-mail about the damn catapult length MELBOURNE - you actually feature in the 4.4Gb PDF about this - in the history of catapulting and these mysteries in the 889 loss section of the A4G section.

I'll bet we refer to the same chap hitting the gunsight (but on different occasions of course). We three were together MELBOURNE late 1971 - no? Yeah again BZ on dat fire.

A recent for 'reels' TYPHOON emergency arrest

Reckon this to be the best Spaz.

My experience is with USN A-4s and classic F-18s. The subjective deceleration upon trapping is certainly robust, but not severe. Perhaps because you know exactly when it's coming. But it is very important to lock the harness prior to trapping. I too often learn the hard way and I only failed to lock the harness once. I flew before the introduction of the Joint Helmet Mounted Cuing System (JHMCS) which adds considerable weight to the helmet, so I don't know what that extra weight does to the experience. But looking at YouTube videos of modern Hornets trapping with the pilot wearing JHMCS (LINK), it appears very similar to my memory of my experience. Don't know how much heavier the F-35's helmet system is, but I would venture the trapping sensation is very similar. I could not find a cockpit view video of an F-35 trap.

'Megan' Doan get me started.... :D


NOW watch the headless chook one armed paper hangar - especially denouement....


THIS is a REAL HEADless CHOOK without enough flight controls....







ROCK STEADY? Supa Etendard

Oh, sh!t, Spaz ... now I've got to watch all those!!

Anyway, the second cockpit video has enough Instruction Leaflets to help him! :)

About a lifetime ago -73 or 74 - did the loads work on Jaguar arrestor hook trials at Boscombe with the RHAG there IIRC the max design deccel was 1g at 200kts The hook was about 25 x 25mm solid steel We looked at a Phantom also on A squadron it's hook was about 125 x 125mm but was hollow Designed for 4g routine arrests! We were unpopular with Boscombe as we wrote off two wires on the RHAG - inner core showing on one and 75mm kink in 2nd - oops Tough life these cables have

A Crab's View!
 

No numbers, but, as a Crab on exchange with the USN in 79, my first carrier landing was in an A-4M on Lexington - a "small" carrier by US standards!!

When I caught the wire (OK 3, naturally!!), both my hands left the throttle and stick and went forward as a result of the deceleration. My kneeboard also went forward and rotated around my knee onto my shin. Having been indoctrinated in the need to select full power on landing, I eventually got my left hand back to the throttle and selected air-brake in and full power. I think all that happened shortly after I had come to a stop. The boat simply called "It's OK - we've got you - you can throttle back". So I did!!

It got better (daytime only!!) but the arresting deceleration bears no resemblance to an arrested landing at an airfield. It is way beyond what you could imagine after a land-based engagement.

As I recall, the A-7 was less stressful - but that might have been a result of some limited experience rather than reality.

My last engagement was in the back of a "heavy" F-14 (Bomcat) on Nimitz - not as violent as a Scooter on Lex, but still enough to freeze the brain!!

As to what my head did - I have no idea, but it's still where it should be and apart from my brain going stupid for a bit, I don't think there was any long-lasting effect - although others might have a different opinion!!

Great fun though - better than a boring landing on a 9000 ft strip of concrete.

Too old now, but I would love to do it all over again...............!!:

:D Congrats 'BomberH' you would have liked the MELBOURNE - a tad smaller than LEXINGTON (I presume you were Carrier Qualifying?). You have described my initial mind state after my first ever onboard arrest very well:
As described in the video earlier by CMDR Clark I thought I was prepared but for not the aftermath. To this day I can only guess what the flap setting was for my first catapult - my mind was just swirling in the aftermath. But here I am - still punching keyboards. :}

One A4G pilot (again - not me Chief - I just collect stories, I never did anything rong) during his first catapult (this time apparently because of operational necessity he did not arrest first but subsequently) DID LEAVE the CATAPULT HAND GRIP in the UP POSITION whilst NOT applying FULL Throttle FRICTION!

He had no hope of keeping the throttle at full during that amazing stroke - luckily it is of short duration whilst the first cat for everyone has extra juice (on top of the light max arrested launch weight). His power went to idle position (but not RPM - winding down) but back to FULL pronto. Bystanding Goofers commented upon the sink off the bow (usually that firstie just leapt of the cat track). Said sprog 'fessed up during debrief with sighs of relief all round for good outcome. Gotta luv the A-4 engine auto acceleration from a reasonable start RPM (whereas the Vampire was utterly hopeless).