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"The reasons HMS Queen Elizabeth has two islands" Topic


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Tango01 Supporting Member of TMP In the TMP Dawghouse14 Aug 2017 9:55 p.m. PST

"In a moment of inspiration back in 2001, an RN officer serving with the Thales CVF design team developing initial concepts for what became the Queen Elizabeth Class, hit upon the idea of separate islands. There are several advantages to this design but the most compelling reason for the twin islands is to space out the funnels, allowing greater separation between the engines below. QEC has duplicated main and secondary machinery in two complexes with independent uptakes and downtakes in each of the two islands. The separation provides a measure of redundancy, it increases the chances one propulsion system will remain operational in the event of action damage to the other. Gas turbine engines (situated in the sponsons directly below each island of the QEC) by their nature require larger funnels and downtakes than the diesel engines (in the bottom of the ship). The twin island design helps minimise their impact on the internal layout.

In a conventional single-island carrier design, either you have to have a very long island (like the Invincible class) which reduces flight deck space or, the exhaust trunkings have to be channelled up into a smaller space. There are limits to the angles this pipework may take which can affect the space available for the hangar. The uptakes can also create vulnerabilities, the third HMS Ark Royal was lost to a single torpedo hit in 1941, partly due to progressive engine room flooding through funnel uptakes.

The twin island design has several other benefits. Wind tunnel testing has proved that the air turbulence over the flight deck caused by the wind and the ship's movement, is reduced by having two islands instead of one large one. Turbulent air is a hindrance to flight operations and aircraft carrier designers always have to contend with this problem. Twin islands allow greater flight deck area because the combined footprint of the two small islands is less than that of a single larger one. By having two smaller islands it allowed each to be constructed as a single block and then shipped to Rosyth to be lifted onto the hull. The forward island was built in Portsmouth and the aft island built in Glasgow…"
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Amicalement
Armand

Supercilius Maximus15 Aug 2017 1:43 a.m. PST

The forward island was built in Portsmouth and the aft island built in Glasgow…

So both will be up for a fight (any time, any place, any where), but one will reek of beer and other of whisky>

Tango01 Supporting Member of TMP In the TMP Dawghouse15 Aug 2017 10:11 a.m. PST

(smile)


Amicalement
Armand

emckinney15 Aug 2017 10:14 a.m. PST

"With separate islands it is possible to site the bridge further forward than in a conventional single-island design. This gives the officer of the watch (OOW) a better view of the bows and what is immediately ahead, especially useful when in confined waters."

Considering the recent collision between the USS Fitzgerald and the ACX Crystal, this won't hurt …

KniazSuvorov15 Aug 2017 3:11 p.m. PST

I've heard surprisingly little criticism about the QE's ski jump. Aren't ski jumps incapable of launching fully-armed-and-fueled modern warplanes? For a long time the prevailing wisdom was that "serious" fixed-wing carriers needed catapults. Or has this problem been fixed?

Lion in the Stars15 Aug 2017 9:17 p.m. PST

The problem was that the Brits didn't want to pay for catapults (not to mention that the gas turbines wouldn't make the enormous amounts of steam required), because they were going to go with the F35B.

Then the F35B was delayed, and the Brits asked about how much it would cost to add catapults, and Treasury said "hell no"

By John 5416 Aug 2017 11:36 a.m. PST

Very true, Lion. It gives me a 'little boy again' glow, that the RN is back in the carrier business, QE, and POW are very modern, automated, modern carriers. Also, I believe the sortie rate is higher with A ski ramp.

John

KniazSuvorov16 Aug 2017 11:59 a.m. PST

Also, I believe the sortie rate is higher with A ski ramp.

Isn't this kind of putting the cart before the horse?
I mean, if your method-of-launch forces you to sacrifice either ordinance or endurance, having a higher sortie rate just means you require more aircrew and more work from your ground crew (or whatever they call it aboard ship) to put the same amount of hurt on target. Doesn't it?

Similarly, it's my understanding that the F-35B is the "Marine" version of the airframe, i.e. the version designed to fly off something that is explicitly NOT a supercarrier. The QE is obviously being marketed as a supercarrier… So what's with the gator navy planes?

Lion in the Stars16 Aug 2017 7:17 p.m. PST

Brits didn't want to pay for catapults on the carrier. End of reasoning.

SouthernPhantom17 Aug 2017 8:44 p.m. PST

Aerial refueling via V-22s or land-based tankers should do a lot to alleviate the endurance issues; F-35s could launch with a full weapon load and minimal fuel to stay under MTOW, then tank up after takeoff and proceed to the target.

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