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Re: Carrier deal signed
Posted: 04 Jul 2008, 15:20
by forthbridge
Interesting points there Skippy..... let's hope it's not a fiasco in the making....
I'm intrigued about the FI on VSTOL aircraft - I would have thought getting catapulted into the air, and wire-grabbing was more fatiguing than a gentle VTOL touchdown
Still, cats would be good, how about the RN placing an order for a few Goshawks for training aircraft? ;-)
Re: Carrier deal signed
Posted: 04 Jul 2008, 15:38
by Garry Russell
I would have thought the vibration sitting on the thrust and sound waves during VTOL operations was about as fatiging as anything could be and far worse that catapult launching
Garry
Re: Carrier deal signed
Posted: 04 Jul 2008, 15:54
by SkippyBing
You're right Garry, as I remember the problem with VSTOL is that the engines run up to full power for both launch and recovery which is at least one more time than a conventional aircraft. You then get airframe vibration and acoustic fatigue (I take it you've heard a Harrier hovering? JSF will be louder which is one of the reasons it's going to Lossie) for the duration of the take off/landing, vice the 1-2 second boost of a cat launch and the one off deceleration of a landing. I remember reading in Air International years ago that the Harrier had about half the life of a comparable conventional airframe, I think the example was the Jag which if you compare to the Harrier GR.1/3 seems about right.
Re: Carrier deal signed
Posted: 04 Jul 2008, 15:59
by forthbridge
Fascinating once again - thanks for that.
This begs the question, why bother with a STOVL version at all?
Presumably the cash saved on dev costs would pay for cats to go on the CVF, not to mention that taking fatigue into account, that effectively doubles the cost per unit compared to the conventional JSF for a marginal if any capability gain....
Re: Carrier deal signed
Posted: 04 Jul 2008, 16:03
by Garry Russell
Yes indeed I've heard Harriers in the full hover and even at display distance there is quite a pounding from the soundwaves,
It must be hard to design something with so many parts and not have some with a distructive resonance range somewhere in that area.
Couple with the other vibrations I would think a slow motion film of componants would be a worrying site at the very least.
Garry
Re: Carrier deal signed
Posted: 04 Jul 2008, 16:36
by SkippyBing
This begs the question, why bother with a STOVL version at all?
It does really. The best answer I've heard is that the RAF won't agree to the RN getting conventional JSF as it's performance is too close to Typhoon for their liking and without RAF support it was uncertain the RN could carry the argument (I mean political support rather than maintenance). There's a small argument they're useful in a land based expeditionary war a la Afghanistan, but there are plenty of non-Harrier types out there doing the job for the US so it's not really a deal breaker. You allegedly have a greater sortie rate in certain weather conditions when operating from the carrier, i.e. in the Falklands, however this tends to ignore the fact that a 65,000 ton warship is less affected by the sea than a 20,000 ton one. The USN did a lot of research into that for the CVX program which is why they're sticking to the 100,000 ton range.
I vaguely recall some Labour politico stating JSF would build on the strengths of the Harrier/Sea Harrier for maritime aviation, presumably ignoring the fact that the Sea Harrier was a massive step backwards in capability compared to the Phantom/Bucc combo.
In short I've never really heard a convincing argument for going STOVL.
Re: Carrier deal signed
Posted: 04 Jul 2008, 18:03
by TSR2
I think the Harrier argument was from cold war days and the ability to lauch without a runway was very attractive for the RAF in places like Germany, however as the world has evolved over the years there is probably less of an argument. I can't coment on the RN side of things as I have no idea.
The curent Harrier is still a very capable aircraft.
Re: Carrier deal signed
Posted: 04 Jul 2008, 20:22
by forthbridge
SkippyBing wrote:This begs the question, why bother with a STOVL version at all?
It does really. The best answer I've heard is that the RAF won't agree to the RN getting conventional JSF as it's performance is too close to Typhoon for their liking and without RAF support it was uncertain the RN could carry the argument (I mean political support rather than maintenance).
This seems absolutely ludicrous! Why on earth should the RAF be bothered if the JSF closely matched the Typhoon? Do they want an inferior aircraft that costs more?
Now, the USMC apparently thinks the B version is good enough to replace it's Hornets and Harriers, and the RAF also wants it to replace it's Harriers - so in other words, the Navy is getting given what it really does not want?
There are I suppose arguments for STOVL, but at the end of the day, even if the aircraft flies identically (which apparently it won's on the RAF argument) - it is crippled with less range as well. Crikey.
Re: Carrier deal signed
Posted: 04 Jul 2008, 22:36
by SkippyBing
Can you think of an argument that justifies a more expensive less capable version of JSF? I can't.
The USMC requirement is driven by a need to have everything VSTOL and able to operate in close proximity to the shore party, hence the technological disaster that is Osprey (by which I mean the wing fold, engine interlink, blade fold nightmare that takes up half the fueslage). The RAF requirement appears to be to replace the Harrier, however why? How often have they actually needed the Harriers capabilities rather than just used them because it's nice to have?
If you were the RAF would you want the RN to have an aircraft that is better than your front line fighter in some regard, i.e. it's stealthier, with a decent A2G load at the same range.
On all logical analysis if you're operating from an aircraft carrier you want the CTOL version. We aren't getting that. You explain why.
Re: Carrier deal signed
Posted: 04 Jul 2008, 22:54
by forthbridge
SkippyBing wrote:Can you think of an argument that justifies a more expensive less capable version of JSF? I can't
On all logical analysis if you're operating from an aircraft carrier you want the CTOL version. We aren't getting that. You explain why.
Skippy, I 100% agree. I can only say when thinking about it, I think of all the behind the scenes discussion that ends up with 'Foot, aim, FIRE!'
I cannot understand why the services are not allowed to select there own equipment, without the other sitting at the back of the room threatening to 'Thqueam and Thqueam'!!!
Basically it sounds like one kid jealous of their neighbour. Someone with the authority should have knocked some heads together, before continuing to harsher methods if necessary!!!! :roll: