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Unread postPosted: 13 Jul 2009, 14:56
by Thumper3181
spazsinbad wrote:thumper, OK, you have your view and 'delusions of grandeur' theory has some validity; but this would be the case if the USA was winding down also. You may know that GB has obligations to its former empire that may not be so strong however they remain. Also GB has to get along (unlike the US) with her allies in Europe. The Common Market/NATO drive a lot of unpleasant decisions for GB...........I think you want to gloss over that the new RN carriers will have a long life, with upgrade potential to future aircraft (after JSF-B) either more STOVL or Navy arrest & cat.

The RN & RN FAA infighting with RAF and ARMY has been phenomenal in tight times. A big decision to spend big on big carriers that should last a long time seems very smart to me - if it works out.

Delusions of grandeur bring us all down in the end. :-)

Delusions of grandeur was probably too strong a term but you got my point. The UK is not winding down it is just going through a rough economic patch and it is feeling the effects of (IMHO) bad government policies.

Obviously Eurofighter was a self inflicted wound. the British thought they where being clever when they wrote the contract and the Germans and Spanish are making sure they buy every frame they contracted for even if they don't need nor can they afford them. The shame of it is that I do not believe they have the same contractual obligation with F-35. They get to make all the aft fuselages for everyone built regardless of whether they pull out or not. The shame is they could have used a single plane (F-35C,B) to replace every fixed wing jet in their inventory for a fraction of the price of Eurofighter.

The UKs global obligations are exactly the reason why they should have went fixed wing. They then would have had a proper carrier fully able to operate independently in a high threat environment. They do not have that with the combination currently envisioned.

I am not glossing over the fact that they have a design that due to its size will be able to grow incapability. I am just saying that they should move to the next step now while it is reletively inexpensive.

Eric ..... Underhill is right. The rolling landing was brought about due to concerns with bring back.

Solomon is wrong. An LHD is not a fleet unit. Too slow. Not enough storage capacity for air ops.

Unread postPosted: 13 Jul 2009, 15:12
by spazsinbad
Whatever the reason 'rolling landings' are a continuation of RN FAA expertise in STOVL ops. They think ahead and plan ahead. Don't make that a negative. The RN FAA stopped fixed wing carrier ops a long time ago. You have not considered what it would take to resurrect all that know how (gone and lost forever). They have the knowledge and will to make STOVL ops work for their benefit. And they will do it safely. They will work it out. No need to worry.

Unread postPosted: 13 Jul 2009, 20:15
by solomon're wrong. it most definitely IS a fleet unit. the only question is in what capacity. NOT MANY NAVIES have the capability of maintaining a cruise speed of over 25 knots....not many modern warships have top speeds in excess of 35 knots...the big deck carriers can and that what there escorts are designed to match. Because the LHD is slower does not mean that it is not a fleet asset and two, that it can't serve in the same role as the other conventional carriers floating around the world's oceans. Especially the LHA(R)....

Unread postPosted: 13 Jul 2009, 23:03
by muir
Part of the problem as I understand it is that no-one knows if and when the emals will work. Since they don´t want nuclear propulsion for several reasons there´s nothing to generate the steam needed for conventional catapults. I´m sure this could be solved but it would cost a lot of money and take up valuable space. This way they might install emals when the ships come in for a first major overhaul in say the mid 2020´s when the technology is more mature. After all, they have had to make do with the small Invicinbles for more or less 35 years when they get the new carriers which will be a great improvement no matter the config.

Unread postPosted: 14 Jul 2009, 02:06
by Thumper3181
spazsinbad wrote:Whatever the reason 'rolling landings' are a continuation of RN FAA expertise in STOVL ops. They think ahead and plan ahead. Don't make that a negative.

They did not think ahead. If they had, the spec for the B would have taken into account a higher bring back weight. Lets not put the cart before the horse here. They may well pull it off but again it's a compromise that was found for a perceived shortcoming after the fact. Don't kid yourself, it is going to take quite a bit of training and practice to master landing an aircraft on a pitching deck that has in effect stalled yet is still deriving lift from it's wing.

solomon're wrong. it most definitely IS a fleet unit. the only question is in what capacity.

Probably the wrong choice of words. They are not battle force units. They cannot keep up with the carriers and her escorts. The LHDs can sustain about 20 - 22 knots, far too slow to accompany CVNs. CVF can only sustain 25 knots, still too slow and probably one of the real technical reasons why they will never fit catapults to them. You may not be able to generate enough wind over the deck for air ops.

I agree, one of the more cost effective things the RN could have done was to build to a modified LHA design if all they wanted to do was sea control. I dont however really know what they want to do with the CVFs but what is clear is that the are too big to be cost effective Invincible replacements and too slow and ill equipped for independent power projection against a first rate foe.

muir wrote:Part of the problem as I understand it is that no-one knows if and when the emals will work. Since they don´t want nuclear propulsion for several reasons there´s nothing to generate the steam needed for conventional catapults. I´m sure this could be solved but it would cost a lot of money and take up valuable space. This way they might install emals when the ships come in for a first major overhaul in say the mid 2020´s when the technology is more mature.

I agree about EMALS but the fact remains at 25 knots sustained and 26 knots max they would have had a hard time getting planes in the air under some circumstances. EMALS will also take a lot of electricity. This capacity has not been designed into the ships either. Bottom line, there will never be cats on these ships if built as envisioned.

Unread postPosted: 14 Jul 2009, 02:28
by spazsinbad
Thumper, you can have your opinion about rolling landings and how difficult that might be. However already the technology to do an automatic rolling landing is in place (read references at beginning of this thread / & / or others). Which ever comes first does not to me seem relevant about the specifications for the JSF-B (after all primarily designed by the USofA) and any thought of 'bring back'. Probably the two notions came together during all the planning for the carrier (and how big it is) and the usefulness of the computer JPALs auto land system already proven with the Harrier trainer (for the JSF-B). The RN FAA will deal with what it has, will plan for what it will get and when both carrier and aircraft are available the RN FAA will prove the worth of the combination.

Kid myself? Fellow A4G pilots landed by day and sometimes by night on a small fleet carrier. Some of the same pilots went off to fly Harriers in the USMC and RN (some permanently). I don't believe any of them thought that Harrier flying was difficult. Navy Pilots train intensively for the deck. RN JSF-B pilots will do the same (having developed proper procedures to do so safely). To give an example of how much training it took to land an A4G on HMAS Melbourne (for most young pilots this would be their first deck landing). After learning to fly the A4G and then posting to the front line embarked squadron, the new pilot would carry out at least 100 FCLP landings - most at night - before going out for their first 'running landings' on the ship. After another sortie or two they would be allowed to drop the hook for their first arrest and catapult. What a blast. After years of training this made them proper Navy Pilots. Bear in mind the RAN FAA had no way train the way the USN does even today with an early deck landing experience with trainer aircraft. If you need reminding - Navy Pilots require particular training in their deck landing skills - this is nothing new.

Claiming that 25 knots speed is not sufficient to generate WOD for catapult launches is plain ridiculous. I think you need to read up on Naval Aviation (at least for the USN).

Your guesswork about possible upgrades to the RN carriers is just that. Stating your opinons as fact does not convince me.

Unread postPosted: 14 Jul 2009, 05:39
by solomon
From Wikipedia...(please note, I hate using them as a source but it was a quick lookup)....

"Carriers steam at speed, for example up to 35 knots (65km/h), into the wind during take-off in order to increase the apparent wind speed over the deck, thereby reducing the speed of the aircraft relative to the ship. On some ships, a steam-powered catapult is used to propel the aircraft forward, assisting the power of its engines and allowing it to take off in a shorter distance than would otherwise be required. On other carriers, aircraft do not require assistance for take off—the requirement for assistance relates to aircraft design and performance."

Russian SU-33 operated off ski ramps but the performance was degraded. Lightly armed and inadequately fueled. Also note that aircraft operating off US ships that are doing 30 plus knots into the wind with full fuel load and weapons/with the aid of a catapult often suffering a "drop off" at takeoff.....if other nations armed and fueled their airplanes to the same standard and only employed ski ramps then you'd have a bunch of expensive airplanes on the sea floor. When it comes to the operation of high performance aircraft (whether fighters or bomb trucks) you need catapults, wires, high speed to get wind over the deck and a big deck to operate from. The latest US carriers come in at 101,000 tons and are nuclear powered. The Queen Elizabeth class is around 60,000 tons. It is at best a hybrid between being a full deck carrier and an LHA (note the LHA(R) or LHA-6 class comes in at 45,000 tons).

Unread postPosted: 14 Jul 2009, 06:18
by spazsinbad
Googling 'steam catapult' will get any number of good hits. Different steam catapults have different lengths for the catapult stroke and different maximum OOMPH! What I know: HMAS Melbourne had a cat stroke length of just over 100 feet (length changed incrementally in a positive direction during refits with bits from Bonaventure added for example). Anyway this 'small' cat could shift the max weight A4G at 24,500lb to flying speed of around 135 KIAS (I'm guessing that one - it has been a while) in under two seconds from the proverbial standing start. Ground speed at end of stroke would be minus the WOD. Melbourne could make about the max. of 22 knots. It was only a problem in nil wind tropical conditions for max weight. If really necessary the 'war shot' of just under 9Gs would get the Maxed A4G airborne. Usually the 6G shot was used as standard for all weights and usually WOD conditions (just to make life simple) all on this 100 foot cat stroke. Of course the same cat had the S2E/G airborne even before the strop dropped off at the end of the stroke. Doing carquals with a lightly loaded A4G with the 6G push was amazing! I have illustrated a simple scenario.

USN carriers have steam cats of some length able to hurl stuff at great speed despite the WOD or lack thereof. Yes there are limitations according to conditions but these would be minimal. Most limitations start to involve the aircraft rather than the catapult itself. For example the A4G was stressed to 9G in the longitudinal direction - hence a limitation. However the cat pressure could be ramped up to break it (but why do that?).

The weight of any USN aircraft is checked carefully at launch time so that the right pressure is applied for the cat shot. Each aircraft type may have individual loadouts thus the shot is varied to make sure aircraft reaches safe flying speed at the end while conversely not overstressing the airframe in error. The Argentine Navy A4s did not get airborne at start of Falklands War because of nil wind with their war loads. However their catapult looked to be way longer than the one on an equivalent carrier Melbourne. But I do not profess to know the type of steam engine powering their catapult - looks like it must have been underpowered.

I hope you understand that there are many variables for a successful catshot. Airframe limits/ catapult limits/ environmental limits including ship speed through the oggin to make WOD. Yes the WOD can be critical depending on so many variables but often it is not. Would you believe it is possible to have TOO MUCH WOD for landing? There are LSO PDF NATOPS manuals online that describe the landing situation.

There are other factors for catapults such as the sea state and how the ship is moving in that environment. Often the cat officer is smart enough to signal the launch when the wave is breaking over the bow such that the usual wait time of a few seconds before the cat fires will allow the bow / catapult to be on the rise as the aircraft reaches the end. Of course every now and then the reverse happens, not that the pilot usually knows about it until he is told by the 'goofers' and 'lollygaggers' onboard at landon time. :-)

Just stating that a carrier is a certain tonnage compared to another certain tonnage does not describe a lot. Ships move in the ocean no matter. Some will move more than others if the swell is such that it 'resonates' with the ship to make it move alarmingly. There are several excellent videos of these factors online. The 'CARRIER' PBS TV series shows one such episode I think. Melbourne moved a lot in some sea states but not in others that one would perhaps guess would make the movement worse. Variables, variables, variables need to be considered. Melbourne was under 20,000 tons (down to 16,000) depending on how it is measured. The landing area from flat ramp start to angle drop off was just over 300 feet. The TA4G could not operate on this short deck because there was not enough time and space to get the longer nose up to bolter or do a touch and go landing. So it goes. The A4G was operated to fit the environment. In the same way the JSF-B will be operated to fit is respective RN and USMC and other environments.

Unread postPosted: 14 Jul 2009, 07:25
by Thumper3181
Remember CVF sustains 25 knots in a calm sea with a clean bottom and fresh engines, IOW right our of refit. Her sustained speed is likely to be somewhat less in the real world. Maybe closer to the 22 knots of your old ship or that of an LHA.

Next, the A4 was truly a marvel of it's day. Light, strong and able to carry a relatively large war load. However it still maxed out at 24,500lbs. F-35 MOTW will be closer to 70,000 lbs. granted the newer catapults on the CVNs have a longer travel but that does not make up for all the increased weight. Also remember the F-35C is only rated for 7.5G in peace time. So just how hard can you drag the plane if there is little wind over the deck? You can only add more pressure up to a point. After that you risk pulling the nose gear off.

I doubt you will be able to launch a fully loaded F-35C with only 22 knots over the deck.

Unread postPosted: 14 Jul 2009, 08:41
by spazsinbad
Thumper all of your above is guesswork. Firstly the vertical G forces (+ or -) experienced in flight are not the same as the horizontal G force usually only experienced in a catapult or arrest or any quick stopping (crash?). I'm referring to the horizontal G force. I bet it will be difficult to know what that is but interesting nevertheless for reason described. You still do not comprehend that a catapult most often can tear the wings off most aircraft, it must be restrained to offer the appropriate amount of power over the length of the stroke within the horizontal G or other aircraft limitation (for example that might be groundspeed for the tyres during the cat stroke - for example the A4G had a 175 knot ground speed limit otherwise tyres burst). The weight is checked before launch so that the catapult is powered exactly as required to achieve the required safe result - no more and no less. Not having been in the USN it would be difficult for me to give the numbers but having read a lot about these issues and from decades of anecdotal evidence (reading APPROACH magazine or GRAMPAW PETTIBONE in Naval Aviation News would be other good sources for 'sea stories') I think my quick sketch of the cat situation is accurate.

Yes you are correct in the sense that any carrier needs to be able to make speed. However extrapolating my story about an A4G to an F-35C is just wrong. It cannot be done. Perhaps a Super Hornet analogy would be more appropriate but other than search the intertubes for such a thing I cannot give you one off the top of my head.

The longer catapult length allows lesser G force to be applied over a longer period of time (within the max tyre speed limits or any other limit). No point in reaching flying speed one second down a four second cat shot. Better to get there with a safety margin at the end. At lower G there is less stress on the airframe. Also if it is a bad (soft) shot then perhaps there is time to stop (unlikely though) or to eject in a timely fashion. For example an A4G at full power ready to go being held back from going forward only by the 'holdback' had no chance of stopping if that hold back broke before the catapult fired. First the engine had to wind down if the pilot reacted instantly, whilst winding down the engine is producing power even after the brakes are being applied from the initial impetus of being at full power with only 100 feet of slippery steel cat track to stop on. I never thought about it. :-) You will see in the PDF videos of the result of two such 'soft shot failures'.

The EMALS will be wonderful for the smooth ride because it will 'intelligently' (according to weight and aircraft type) apply G in a fashion over the length of the stroke to minimise the G force but achieve the required result. An A4G cat shot was just WHAM!

So to answer your last statement. I would guess that much has gone into calculating (given all the variables of aircraft launch weights, catapult length and power) that there will be no issues with being able to launch the JSF-C under any conditions on the NUKE carriers (only ones left now). I have read/heard anecdotal evidence that some USN aircraft have been launched whilst the carrier was going downwind. I have a pic somewhere from Naval Aviation News cover showing an A4 being launched from a carrier at anchor. Bear in mind usually a ship at anchor will point its nose into the wind if the tide does not compel it to do otherwise.

NavAv is fun right? :-)

Unread postPosted: 14 Jul 2009, 10:56
by spazsinbad
Naval Aviation News Magazine cover August 1962:

Unread postPosted: 14 Jul 2009, 17:54
by solomon

whats your point son? its a piss ant of an airplane! the carrier is the size of a LPH-2 (or rather just a bit bigger)...even at it ultimate development the Singapore version its still a light strike fighter. to compare it to modern day, heavy wt naval fighters is a misnomer. why can't you see that. WHO CARES THAT IT CAN LAUNCH OFF THE DECK WITH WHO KNOWS WHAT PAYLOAD! They've launched C-130 off carriers, OV-10's off carriers etc....just cause you can do something doesn't make it operationally PRACTICAL! i got drawn back in because Thumper3181 pinned you like a UFC fighter, pounded your statement like a piece of cold meat and sent your "version" of the facts back to the showers....but like a bad dream you won't let this go! help.

Unread postPosted: 14 Jul 2009, 19:05
by spazsinbad
solomon, you do not seem willing to comprehend. Not my problem. Thumper has made statements that should have been in the form of questions. I answered with knowledge that I hope could allow thumper to understand that what he was alluding to was just plain wrong. You yourself do not seem to understand how a catapult works; nor how it is used today in the USN. Not my problem. If I used in your eyes inappropriate analogies then once again not my problem. Not having flown current USN aircraft off USN carriers it would be wrong for me to speculate, but easy to tell my own story. On the net there are plenty of stories and information that could explain further about the steam catapult. I was attempting to explain from my own personal knowledge and experience and understanding. I gather you have none. Seek help yourself. I do not believe I have answered any question in an insulting manner and would request that you take your medication before replying. Thanks.

I liked the way you react to pictures. You yourself seem to only respond with invective or a pretty picture. I guess that is your only level of understanding. I will not be bullied by you.

Unread postPosted: 15 Jul 2009, 00:09
by StolichnayaStrafer
Something wrong about that picture...

how many carriers launch aircraft with an anchor down???

Unread postPosted: 15 Jul 2009, 01:20
by spazsinbad
At least one.