The blast deflectors on conventional carriers are used to protect personnel and equipment (such as another aircraft waiting to use the same catapult) from the blast of the aircraft taking off. Catapults on an American carrier are at the front of the ship with most of the flight deck behind them or half way back with still a large area behind with operations on going. On the Queen Elizabeth ships the F-35B will start it's run from the rear of the ship and travel the full length before using the ski jump to fly away. Nothing behind the jet when it starts its run.

Turin,

Perhaps I can help.

Jet blast deflectors (JBDs) are still used with the F-35C, because like other USN jets, it launches with its exhaust pointing straight aft parallel with the deck (sometimes in reheat), and that severe and concentrated blast needs to be diverted upwards and away from aircraft and personnel in the vicinity of the catapults.

dat581 - remember that the USN carriers also have waist catapults, about half way down the deck.

The F-35B launches without a catapult, with its aft nozzle deflected onwards towards the deck. (On the QEC many of these launches will be about half way down the deck, not often right aft). The normal JBD design would not work with this, and moreover the launch position up a ski jump (or with a flat deck STO) is adjusted with launch weight and wind over deck (WOD), so a fixed JBD wouldn't be of much use.

Even so, the F-35 programme did look at other JBD designs and there were some that might have had some effect on the F-35B efflux, but early trials and further analysis showed that once the efflux hits the deck it spreads out and slows down very rapidly. Given this, the hazards can be adequately controlled by suitable precautions on where to stand during launches. The same goes for recoveries.

Hope this helps, best regards as ever to those who are going to work the decks,

Engines

Thank you. Makes sense.

I wonder if the F-35B will be worse than the blast from the F-4K which was set well below the horizontal due to the installation of the engines and the AoA for launch from the ship. I remember reading about the Phantom trials aboard HMS Eagle required a steel plate to be fitted to the deck to protect the ship with fire hoses used in between launches to cool it. It seems like this problem is nothing new and I suspect a storm in a tea cup.


Engines -


I should have been more clear than saying at the front (bow cats) and half way back (waist cats).

Dat,

The straight answer is (I think) no, the F-35B won't be anywhere hear as bad as the F-4K. Let me explain.

The F-4K had two Speys, each rated around 12,000 pounds thrust dry and 20,000 pound in reheat. As far as I can see, most F-4K cat launches were in reheat, so there was about 40,000 pounds of very fast and very hot gas involved, withy the nozzles just inches from the deck.

The Ark Royals' JBDs were (I think) actually designed for the ill fated CVA-01 and the P1154, and were designed to handle a very hot jet efflux striking the deck. They included water cooling for both deck and the moving plates, which included a short side plate each side of the main JBD plates, designed to contain the hot gas sheet flowing out across the deck.

The F-35B launches with the main engine operating in dry thrust at around 18,000 pounds thrust, because 50% of its power is being extracted via the drive shaft to power the front lift fan. The engine is deflected down around 10 degrees at launch, with the nozzle some feet above the deck.

So, by the time the F-35B main engine exhaust hits the deck, it is already spreading out, slowing down and cooling.

The reason I can be fairly definitive on this is that I worked closely with the very good BAe team at Fort Worth and Warton whose task was to predict, model, validate and finally confirm the F-35's external environment (for all three variants) in all required operating areas, including carrier decks and short strips. They were helped by a similarly very good team assisting the CVF guys in the UK with some excellent CFD modelling.

I hope this helps, and also helps illustrate to some readers that the team producing the F-35 have taken a thorough and professional approach to delivering a powerful and substantial powered lift aircraft into service. Put another way - they aren't numpties.

Best regards as ever to all those Brits doing the F-35B business,

Engines

This may give a better idea why the JBDs on the Ark were so substantial and water-cooled. Generally the F-4K was sitting in reheat for 10 or more seconds before the cat stroke and the increased AoA (extra NLG extension) was considerably more than that on the USN models.

http://www.eacott.com.au/gallery/d/1...+waist+cat.jpg

http://www.eacott.com.au/gallery/d/1...al+1974+04.jpg

Compared to this:

http://www.eacott.com.au/gallery/d/3...st+cat+Ark.jpg

The F-35 will not be stationary for protracted periods in the one spot with the same angle down of jet exhaust, as previously mooted.

John,

Thanks for a great post - pictures tell a thousand words, in my case a thousand really boring words.

The picture of the Ark Royal JBD shows the unique low side panels designed to contain the sideways outwash. This unique layout appears on deck plans for CVA-01, hence my guess that they came from that project.

Best regards as ever to those watching where they go on deck,

Engines

Trust me Engines, nothing you have ever posted has been boring!

Engines-

Thanks for the reply. A very informative post as usual. Basically the heat problem seems to be a storm in a tea cup much like the Super Hornet wing drop issue and other small problems blown out of proportion by people with an axe to grind.

Dat, Draken,

Thank you - I'm just trying to help people understand the issues faced in getting an aircraft like F-35B to sea.

Yes, there's a heat (and blast) issue - and it's a bit more than a storm in a tea cup. You don't get 35,000 pounds of aircraft to hover yet still go supersonic with a decent weapons load without a significant amount of jet blast. But it's an issue that can be handled by the usual array of measures we've been doing at sea for some time.

Jets on a flight deck, with lots of people, weapons, radio emitters, and a moving ship have always been an issue, and they will stay an issue. Jet blast is just one of those special factors (proximity, time pressures, safety, etc) that make maritime aviation so different (not better, just different) from land based ops. Teams like the FAA and the USN make flight deck ops look easy, pretty much like top athletes make their performances look easy. They're not.

Best Regards as ever to all those who post,

Engines

A question for those who have been around a while.

How did the USN aircraft cope when cross decking onto our smaller carriers in old school F4s etc?

No extended nose leg etc.

SRVL
 

Picking up on Engines' helpful posts above and the comments about the difficulties of lots of people on a flight deck, does anyone have a view on how easy it will be for the F35Bs to SRVL on the QECs so that a higher bring back load can be achieved?

Personally I can see the requirement for a barrier raising itself, sorry about the pun. If something goes wrong during the SRVL I do not feel that there will be enough time to spool up the engines to launch again. Happy to be proven wrong.

Tourist, see here:

https://groups.google.com/forum/m/#!...al/sOeMJ5aZSwo

PhilipG, PM me pls.

MSOCS, the system tells me you are not allowing PMs....

Try again now Phil

Thanks ORAC, seems like not a big deal.

In answer to Tourist's question; see the photo of the VF 32 F4 on Ark's waist cat. Having flown both types off the deck, only minor control input required with the USN F4 off the front end. The F4K was already "set-up", BUT always had to remember to unclip the stick positioning wire after the launch. (think about it!)

I see the unions on Clydeside still say there is no cash for the T26 order

'No redundancies' over frigate 'delays' - BBC News

the MoD is still going mumble mumble mumble....

http://data.parliament.uk/writtenevi...oral/35261.pdf

The MoD going mumble, mumble, mumble is here in all its glorious detail......

Not that it belongs in a Future Carrier thread mind.