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Feb 22 12 4:25 AM
MattReloaded wrote:HK wrote:Here's my take on a low-cost, STOBAR CVL. My starting point is Cavour, but with some significant cost reduction.
Air group capacity would be about 16 Rafale M (6 on deck, 10 in hangar) or 20 Gripen NG, plus a few AEW and SAR helos. after all? In this article from Mer et Marine, they seem to suggest that the CDG airgroup won't be more than 30 aircraft in total, i.e. 24 x Rafale, 2 x Hawkeye and 4 x helos.In the same vein, according to Brown's Rebuilding The Royal Navy (page 198), one of the early studies carried out for CVF showed a 39kt CATOBAR carrier with an airgroup comprising 20 x F/A-18, 3 x S-3A and 3 x Merlins. Can a 30kt STOBAR CVL reasonably be expected to be able to carry as much as 16 x Rafale, plus a few AEW and SAR helos ?
HK wrote:Here's my take on a low-cost, STOBAR CVL. My starting point is Cavour, but with some significant cost reduction.
Air group capacity would be about 16 Rafale M (6 on deck, 10 in hangar) or 20 Gripen NG, plus a few AEW and SAR helos. after all?
Feb 22 12 4:31 AM
Every time I see the video clip with this (poor quality still frame as shown) I am gasping at the poor landing. We don't know any details - what the LSO may have been screaming on the radio :-) or whatever else but it sure is a classic 'taxi one'. I could make the clip available on Utube at some point. When it is there I'll post that info here. However the long version is quite entertaining (once removed). :-)Hah, the 'streak marks' in the aft lift can be seen also in the screenshot. I guess the lift was heavily reinforced. A long greyscale film of these and other events of note can be seen at the 'bengello' Utube site:A4G Skyhawk on HMAS Melbourne Deck Ops early 1970s
http://www.youtube.com/watch?v=Vy0vWedmc_4&feature=plcp&context=C39a5a6bUDOEgsToPDskJmZA2enoqnczuqu5qanp8XSmoke from main wheels shows touchdown before no.1 wire. Shudder....Click Pic:
Feb 22 12 5:44 AM
Feb 22 12 5:53 AM
HK wrote:- Replace the four LM2500 22MW gas turbines one-for-one with four Wartsila 16V38 11.6MW diesels, with waterline exhausts. Top speed drops to ~24kts sustained deep & dirty, and ~26kts for trials. The diesels should fit in the same machinery room space, though they do add ~300t of weight deep in the hull (which might actually be positive for stability). On the plus side, the diesels also guzzle ~25% less, which allows you to store up to 40% more aviation fuel. As for the waterline exhausts, the rationale is that they eliminate a whole lot of trunking and allow for a much smaller island. Hopefully the fumes won't get into the hangar!
Feb 22 12 7:13 AM
Feb 22 12 3:32 PM
HK wrote:My gut tells me that EMALS/EMCAT would be very expensive. I'd wager that you could pay for another 5,000-10,000t worth of STOBAR carrier for the same price... and between a 40,000t STOBAR and a 30,000t CATOBAR carrier I would pick the former.
Feb 22 12 4:47 PM
HK wrote:- Replace the four LM2500 22MW gas turbines one-for-one with four Wartsila 16V38 11.6MW diesels, with waterline exhausts. Top speed drops to ~24kts sustained deep & dirty, and ~26kts for trials. The diesels should fit in the same machinery room space, though they do add ~300t of weight deep in the hull (which might actually be positive for stability). On the plus side, the diesels also guzzle ~25% less, which allows you to store up to 40% more aviation fuel.
Feb 22 12 5:06 PM
Feb 22 12 6:08 PM
HK wrote:- Eliminate the expensive long-range search radar, sonar and local air defense systems (rely on escorts for this).
Feb 22 12 7:09 PM
NewGolconda wrote:The 24 Superhornet for the RAAF are going to cost roughly US 5 billion, once you include ten years spares and training support. That’s an operational force around the mid teens - which is in the ballpark of a CVL air group.
The acquisition costs of an economy CVL - a stretched ski jump, arrested landing Juan Carlos or something, around 30-35,000 tons - are going to be in the US 1.5-2.5 billion range, unless you are operating with unusual costs structures with third world labour rates. The higher figure is probably more comparable to the "10 year" super hornet price tag, with spares and training.
If you want some escorts for the carrier group - let’s say 3-4 minimalist F-100 AWD ships are going to be 2 billion as a minimum - probably more like 3-4 billion on our "10 year" basis.
We are going to need at least at least a dozen modern ASW helicopters for carrier and escorts - hard to get by with less than 2 billion here.
We could park up all of the other associated costs, intermediate trainers, a fleet train to make the task force long term deployable, shore based infrastructure.
So the “10 year” acquisition plus initial support costs for a CVL based task force are something like.
Airgroup – 40%
CVL – 20%
Escorts – 24%
ASW choppers – 16%
Total – US 12.5 billion 100%
On this basis – a larger ship with an EM catapult might cost you what, another billion? <10% of the total task force cost? And what do you gain in terms of air group effectiveness over a small ship with a 9deg ski jump? 25% - 40%?
The bigger ship is going to be able to recover aircraft over a wider range of weather conditions, and store more fuel and munitions. In fact, you might be tempted to increase the size of the ship again to maximise those factors. What’s that – another billion, but only another 10% in terms of the cost of the task force. Of course, we can now carry two dozen Hornet sized aircraft or more, if we can afford it.
All of a sudden we are in CVF territory.
If you are using full priced, modern first world jets in the airgroup, the airgroup costs swamp the carrier costs – have from as early as 1960 from what I have colated. Which means spending more money on the carrier to optimise the performance of the airgroup is exactly what you are going to do – which then goes on to explain US, British, and even French (in the last decade) carrier decisions since the mid 50’s, and why we so few conventional CVL’s entering service.
Feb 22 12 8:27 PM
Feb 22 12 9:03 PM
Feb 22 12 10:02 PM
MattReloaded wrote: I'd go for IFEP, with 8 x 16V32 diesel gensets @ 8,900 kWe each and 2 x electric motors @ 30 MW each. Sustained speed would be about 27+ knots deep & dirty, and 29+ knots for trials.1) Space and weightThe 16V32 genset is fairly compact (L x W x H = 11,175mm x 3,080mm x 4,280mm). Lengthwise, it would in fact be slightly more compact that the CODAD arrangement proposed with the 16V38 diesel engines once the gearbox is taken into account (16V38 length = 8,900mm, TCH380 gearbox length = 3,680mm). As far as weight is concerned, each 16v32 genset is about 120 tonnes, i.e. 960 tonnes for 8 gensets. The electric motors would be somewhere between 100 and 150 tonnes each (lower figure is for PMM, higher figure for AIM), i.e. 200 to 300 tonnes in total. The machinery weight for the Clemenceaus was somewhere around 2,000 tonnes. Compared with the Clemenceaus, the diesel-electric propulsion would cut the fuel consumption by about 50%, meaning fuel bunkerage could be reduced from 3,700 tonnes to 2,500 tonnes.2) CostBased on the numbers available for the Type 45 and the CVF (see here, here and here), IFEP costs could be as follows :Diesel engines : $70 million (8 engines @ $9 million each)Alternators & motors : $100 millionPower Control & monitoring : $30 millioni.e. about $200 million in total.The CODAD arrangement proposed by HK would probably cost around $90 million ($45 million for the 16V38 diesel engines, $30 million for the reduction gears and $15 million for the diesel gensets).
Feb 22 12 10:14 PM
MattReloaded wrote:Below are some rough estimates I came up with for the 30kt STOBAR I have in mind :1) Main particulars :Draft @ max displacement = 7.5 meters3) Typical airgroup20 x Tejas Mk2 aircraft (or equivalent)6 x ASW helos (Merlin ASW ?)3 x AEW helos (Merlin AEW or BA609 AEW ?)5) Displacement breakdownLightship = 23,000 tonnes
Feb 22 12 10:50 PM
hrfcarl wrote:For lower rank counties, obtaining nuclear reactors is an issue, so this question is for those countries in the nuclear club: Is nuclear power too expensive (personnel & materials) and/or space consuming vs gain in fuel storage and endurance for a smaller class of carrier?
Feb 23 12 1:19 AM
Feb 23 12 2:12 AM
Feb 23 12 3:18 AM
HK wrote:- You're replacing four compact GTs ( LM2500, 8.2m x 2.7m x 3m, 22 tons) or four slightly larger diesels (16V38, 8.9x 3m x 4.7m, 110 tons) with eight very large gensets (16V32, 11.2 x 4.3m x 3.3m, 140 tons). Add in the 80t weight differential between a mechanical gearbox and electrical motor... now that's 800 tons more weight and 125% more volume than the CODAD solution... which itself is 300 tons more weight and 200% more volume than the baseline COGAG solution on Cavour. So you're looking at a much larger hull... 35,000t?
Feb 23 12 3:25 AM
Feb 23 12 3:27 AM
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