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Take off run/landing on new CVF

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Take off run/landing on new CVF

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Old 6th Nov 2002, 12:37
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Take off run/landing on new CVF

The Thales design for the new CVF shows a center line runway spanning the whole length of the ship. The gives a take off run of up to 950 ft length for a GR9 or F35. With a 25+ kt WOD could a Harrier achieve wingborne flight without the need for vectored thrust? I understand that a GR7 leaves Invincible's deck at about 90kts, what would be the result of the extra take off length on a CVF?

Similarly with a 950ft strip available does this make the a rolling landing an option for a higher bring back weight?
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Old 6th Nov 2002, 16:44
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yes I read somewhere that the larger deck will allow significantly greater bring back capability than is currently on the CVS. Yet another good reason why the build em big philosophy is so sensible - it will save a lot of bombs and guns
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Old 6th Nov 2002, 17:44
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And make bigger bubbles when it sinks.
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Old 6th Nov 2002, 17:51
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Speaking as an amateur in such matters, I believe the answer to be a probable yes, but with possible problem areas to be addressed. e.g.

The VSTOL version has had weight pared away from the main structure and all the undercarriage components to offset the weight of the lift fan. It is not as robust as that of either the CTOL or CV models. It also shares the wing and control surfaces of the CTOL version, not the larger wing and control surfaces of the CV, increased to permit reduced approach speeds. It may not, therefore, have the control margin required to bring back the increased/assymetric weight at a speed compatible with the available landing distance, or to accept the increase landing forces; and it has no hook, so the braking system might also have to be uprated to provide the required braking forces.

I presume the same holds true for take-off. The airframe will be stressed for the undercarriage compression and rotational forces experienced at the present planned speed range reaching the jump. If you increase the aircraft weight and speed these forces will increase and the structure may have to be reinforced to take them. Additionally, after leaving the jump the aircraft will have to maintain stability inside an increased weight/CofG envelope whilst speed increases, which may also require changes to control forces in either/or software and hardware to maintain margins.

All the above are possible, but at the expense of adding weight, which means reducing fuel or weapon load. It's a trade-off that someone will have consider it the capabilities are considered desirable.

I can't imagine that it won't be done, and that it won't provide increased take-off and landing weights, but, unless it's in the contract and the test schedule, it may be later rather than sooner.

Last edited by ORAC; 6th Nov 2002 at 19:13.
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Old 8th Nov 2002, 22:22
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"And make bigger bubbles when it sinks"

interesting piece of trivia for you - during vietnam there were a number of major fires on US Carriers - one of the worst was when 134 men were killed and the damage was worked out to be the equivalent of 14 cruise missile hits. How long did it take the carrier in question to start using her planes again and flying combat missions?
months? no
weeks? no
days? no
Hours - yes it took about 6 hours and the carrier was flying again.

Bear in mind that CVF will be a similar size and with vastly improved damage control - this sort of incident shows how wrong the claims are that carriers are easily sunk - they are far more survivable than some people believe...
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Old 8th Nov 2002, 23:01
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Jimlad

'Twas the Forrestal, the fire caused by an unintended radar transmission causing a warhead to accidentally detonate.

I think our friend Flatus is using the same tired old arguements againsts carriers (and the Navy per se). They were wrong yesterday, and they are still wrong today.

But......will the Navy have enough fixed wing pilots considering the effects of recent decisions?

Last edited by WE Branch Fanatic; 9th Nov 2002 at 10:07.
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Old 9th Nov 2002, 01:37
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To correct a lot of disinformation,

Yes it was the Forrestal, no it wasn't a radar transmission.

The fire was caused by the unintentional firing of a Zuni rocket which impacted and set on fire an aircraft on the other side of the flight deck (The now senator McCain's). This caused a fire causing the bombs on the aircraft to explode causing a chain reaction. The fire was exacerbated by the fact that 8 of the aircraft were carrying WWII vintage bombs of which detonated in less than 2 minutes before the fire suppression equipment could gain control. Six of the aircraft exploded with 9 explosions caused by the detonation of their 1000lb bombs.

The rocket fired due to a power surge as the aircraft went to internal power. This was a known possibility which should have been prevented by two safety mechanisms. Firstly, the firing plug at the back of the rocket pod should not have been connected till the aircraft was on the way to the catapult; secondly, the TER pins should only have been pulled on the catapult. Unfortunately, the safety board on the carrier had approved the plug being attached to save time during combat operations, relying on the TER pins; the deck crew meanwhile had got into the habit of pulling the pins early.

The fire started on 291051 July 1967, the last major fire was extinguished at 300400 July - 17 hours. The fires were fought by crew of the carrier plus all the fire trained crew/equipment which could be flown across by helicopter plus destroyers laying alongside. Smaller fires occured as compartments were re-opened at Subic and en-route back to the USA.

A total of 21 aircraft were destroyed, including those bullozed off the deck to prevent further explosions - including 3 intact RA-5C Vigilantes.

The Forrestal was immediately withdrawn from operation and ordered to withdraw back to the Norfolk. She suffered major structural damage which required the removal of the entire rear half of the flight deck. All aircraft were off-loaded by crane, no further aircraft flew from the Forrestal. She only returned to service after structural repairs and a complete refit. She never returned to Vietnam.

The wonder was they managed to prevent the fire spreading to the aircaft and weapons below. The crew below in hangar 3, working in thick black smoke and a rainstorm of water from the flightdeck, went from aircraft to aircraft disconnecting the bombs and missiles by hand and carrying them to the elevators to dump them overboard.

facts courtesy of "Sailors to the End - the deadly fire on the USS Forrestal and the heroes who fought it" by Gregory A. Freeman.

Last edited by ORAC; 9th Nov 2002 at 05:59.
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Old 9th Nov 2002, 04:40
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o Jim ad about this carrier being operational again and flying aircraft after 6 hrs, perhaps your facts on super duper carriers are a little false?
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Old 9th Nov 2002, 10:01
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There was a fire aboard another carrier off of Vietnam, and I think this is the one ORAC (and maybe Jimlad) are referring to. The fire aboard the Forrestal was definately due to electrical interference.

"The rocket fired due to a power surge as the aircraft went to internal power." This was due to lack of attention paid in those days to Electromagnetic Compatibilty. I was right about the source of the problem..

RF Energy as a Source of Ignition

The Forrestal

On July 29, 1967 the USS Forrestal (CVA 59) was cruising in the Gulf of Tonkin off the coast of North Vietnam when it experienced the worst carrier fire since World War II. The Forrestal had several A-4 Skyhawk jets on deck, fully fueled and armed with a variety of air-to-air and air-to-ground ordinance. A Zuni rocket was accidentally launched. The missile hit a parked A-4, igniting its drop tank. The resulting fire burned for 13 hours, claimed 134 servicemen, caused $72 million in damage and required 7 months to repair the ship.

Subsequent investigation showed that the missile launch was caused by perturbation of electronic systems being subjected to a powerful electromagnetic field. One of the missile cables apparently had an improperly mounted shielded connector. When a shipboard radar illuminated it, RF voltages were developed in the degraded connector, resulting in a Zuni rocket being fired across the deck.

Of course, increasing the range between the source of the energy and the potential victim can easily reduce the risk of similar electronic upsets. This is a primary reason for locating airport radar antennas in relatively remote areas of airfields. By calculating the maximum effective radiated power of an emitter, an appropriate minimum safe range can be defined. The critical piece of information in this derivation is maximum power from the antenna.


From http://www.dallas.net/~pevler/RF_Ignition.html

See also DEF STAN 59-41 Part 7. Sounds like the "rusty bolt effect".

The fire aboard the other carrier (name escapes me) was caused by careless handling of a Zuni rocket, and killed 44 men.

Perhaps we are confusing the two incidents....

Last edited by WE Branch Fanatic; 9th Nov 2002 at 11:59.
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Old 9th Nov 2002, 15:10
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Quote: "two of the crew members working with Bangert's plane were busy checking the missiles and rockets to ensure that they were properly installed and that the systems were safe. One man began conducting stray voltage checks on the weapons systems, to make sure the electrical system was not malfunctioning in a way that could accidentally trigger the weapons. He found no stray voltage in in any of the weapons on the port side and then went to the starboard side to conduct the same tests. Having found no stray voltage or other potential problems with the weapons systems, he plugged in the "pigtails" cable connectors that linked the rockets and the aircraft's launching device. This was the shortcut approved by the ship's administration for the sake of speed. Plugging in the pigtails armed the weapons on the port side.

At 10:51:21 AM, Bangert had just started his starboard engine. With the engine running, Bangert reached out to press the button that would switch from the external cart's power supply to the plane's internal system. As his gloved finger hit the button, Bangert and McKay both felt a mild explosion shake the plan. Bangert looked up in time to see a small rocket flying across the deck with a yellow-orange exhaust flame".

Quote (Captain Beling): "The rocket fired when the pilot of F-4B number one-ten moved his generator switches from the external to the internal positions"

The incident was exhaustively investigated by a team lead by James Russell, the recently retired Chief of Naval Operations. Whilst there were several contributory factors, the firing of the rocket was put down to the poor design of a brass slide switch from the TER rocket-arming system.

Quote: "The rocket pigtails, the TER safety safety pins, and all the other factors still mattered, Russell said, but the rocket fired because the electrical surge made it's way through safety switches like that one".

Whilst in no way disputing the effects of induced currents, it was not, in this case, the cause. The evidence of the pilot of the aircraft would appear to be conclusive. All the aircraft on the rear deck were totally destroyed during the fire, Bangert's F-4 included, so I am intrigued as to how anyone can claim that an improperly shielded cable connector was responsible - in contradiction to the testimony of those present. It would seem to require the fault to have occurred in the moments after the checks had been completed, and simultaneous with Bangert's switch to internal power. Occam's razor would seem to apply.

It should be pointed out that the claim is made on the web-site of a company offering services dealing with said inerference.

----------------------------------------------------------

There had been an earlier accident on Yankee station, on 26th Oct 66, involving the carrier Oriskany. That accident, however, involved the accidental ignition of Mk-24 Model 3 flares inside an unofficial flare locker - which was directly above a row of officer staterooms. The fire started at 0700 following a handling accident and burned till 1158. Eight enlisted men and 36 officers died, including 24 pilots. No Zuni rockets were involved.

Virtual Wall of Rememberance

Last edited by ORAC; 9th Nov 2002 at 19:00.
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Old 10th Nov 2002, 13:34
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didnt say it was Forrestal and I cant remember the source - when I do and if this thread is still going then I shall post it for all to see.
Interestingly this problem of flight deck fires seems to have disspeared over the past few years - I have no recollection of hearing about one for a long long time. Does anyone know why?
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Old 10th Nov 2002, 14:27
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As a result of the Forrestal fire all carriers were fitted with an integral water/foam "wash-down" system consisting of hundreds of recessed sprinkler heads in the flight deck. This can be activated instantly from either ther bridge or flight control.

Additionally, they also now carry fire trucks on the flght deck, manned by specialist role firemen, designed to bulldoze aircraft off the deck if required.
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Old 10th Nov 2002, 17:24
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To revert to more mundane matters - like the original question.

It is true that simple theory suggests a Harrier (or other jet lift device) must be able land at higher weights if the touchdown site is big enough to allow the use of forward speed, but in practice there is a very deep nasty black hole before you win on weight.

A free air hover can be safely entered into alongside a ship with a negligible power reserve. If you turn out to be too heavy you just trickle past the steamer at a hundred feet or so and creep back on to your wings. No harm done. If on the other hand you can hover alongside, then because you are using fuel nicely it will not be long before you are happy to translate sideways and VL on. Having commenced the descent to the VL you may well be committed to touch down, but so what. You are over the spot, it is not going to go away and all really is no sweat.

Now let us say you are 500lb above free air hover weight and wish to land on using a tad of wing lift. Let us say the wings need 50 kts to produce this lift. You are now flying any aeroplane that needs to keep going at 50 kts on the approach. You have to be lined up, you have to get the glide path sorted, the strip must be big enough to cope with pilot induced scatter of touchdown position and stopping distance, and finally the crunch issue, you must have a power reserve to do a go around just like any other conventional aircraft on finals. This power reserve means you cannot be on short finals with anything like the jet lift you CAN use approaching a free air hover away from obstacles. Putting numbers to this even 1000 lb of thrust reserve does not give a punchy go around with on a 18000 lb jet.

This gives the performance hole as there will be a minimum airspeed on finals to replace the jet lift lost by the need to maintain a go around capability, before you add the airspeed needed for the extra payload you crave. All this means you may well find yourself with a minimum touchdown speed of lots of kts before you actually bring back more than you can with a heavy VL. Sad isn’t it?
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Old 10th Nov 2002, 17:27
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My not-very-profound bit of banter seems to have stirred it up a little. By way of comparison, I watched a demonstration of airfield damage repair by the Sappers at Leuchars in 198(3?). They blasted a crater in a taxiway with a charge equivalent to a 1,000 lb bomb. WHen the brass (and yours truly) were assembled (well watered and dined) on the special grandstand, the staish gave the signal for battle to commence. Even using the techniques available 20 years ago, a F4 taxied over the "crater" at a good clip about 30 minutes later. If you think carriers are hard targets, try airfields!
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Old 10th Nov 2002, 21:44
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There was also a fire on the Enterprise in 1969 while it undergoing [working up for?] an ORI. I don't have the details to hand, but seem to recall that another Zuni was the cause, set off by the exhaust from a deck vehicle.

JimLad - I wonder if you're thinking of one of the old UK pacific fleet carriers? Victorious and Implacable both took kamikaze hits and in the case of the latter, the flight deck was 'reasonably operational' a few hours later; I think the same was true for the Victorious .
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Old 10th Nov 2002, 23:40
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Wasnt there a fire on the Enterprise a couple of years ago when Picard had to scuttle it to destroy the Borg?
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Old 11th Nov 2002, 10:45
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And there were several when Kirk was Captain, from what I recall - surprised he wasn't relieved of command given his obvious failure to adhere to H&SW legislation...
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Old 11th Nov 2002, 11:39
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nope = wasnt the old UK fleet carriers, though they are a good example of how survivable a carrier can be. It was very definitely the US one's.
I think the carrier gets a bad press for its survivability, firstly the enemy has to find the damn thing, then he needs to break through the air defence and then he has to sink it. Very very few nations imho possess the ability to do this. Airfields are also survivable but possibly slightly easier to find - mustapha merely needs to buy an OS map
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Old 11th Nov 2002, 12:51
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The UK fleet carriers of the second world war certainly were hard to sink, as the examples of the kamikaze hits (sweep the bits overboard) and the Illustrious being bombed to bits by the Germans show. (granted, there was no flying off her for a long, long stay in Malta Dockyard, but she didn't sink) But is that the right question?

The British carriers benefited from armoured protection, but that might not have been entirely a boon. The Americans and Japanese both went without, making the carriers much more vulnerable, but they could have a lot more aircraft on a ship of similar size. The Victoriouss could take punishment alright, but they often had to. If bombs are falling on a carrier, then its primary purpose has not been achieved - to win the air-sea battle. An aircraft carrier is only as good as its carrier air wing - it is there to carry aircraft.

On the point that airfields are harder to destroy, two things come to mind. First, this is irrelevant if they're in Oxfordshire and the war isn't! Secondly, what about unconventional weapons - ships are harder to attack with these than airfields, after all they move. And how quickly would those sappers have built a new airfield if Leeming had been poisonous/infectious/glowing/gone? Or less dramatically, could they have done it so quickly in their NBC kit?
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Old 11th Nov 2002, 15:23
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Carriers to carry aircraft to win the air/sea battle? Not according to Mr Hoon and Mr Ingram. After all, its not like we have ever needed to use aircraft like the Sea Harrier to defend the fleet ot sea, is it? And we wouldn't ever face an enemy that has lots of aircraft, is it?

The fleet will be better defended by ground attack aircraft than it would by fighters with AMRAAMS - Ingram and Moonie have said so. Just you wait, the Government will try to procure a pure ground attack version of the F35.

Unless someone can stop them.....
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