COGAG Spey instead of COGOG Tyne/Olympus

Anderman

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Anthony G Williams had the idea to use RR Speys in a COGAG combination instead of the used COGOG on RN ships.

http://www.quarry.nildram.co.uk/Alternative%20RN.htm

Is this a realistic idea ? The Type 22 are much larger then Williams 2750 t frigate so would this ship had enough speed with two Speys?
And how much power would the RR marien Spey had have in the 70´s ?
 

TinWing

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Anderman said:
Anthony G Williams had the idea to use RR Speys in a COGAG combination instead of the used COGOG on RN ships.

http://www.quarry.nildram.co.uk/Alternative%20RN.htm

Is this a realistic idea ? The Type 22 are much larger then Williams 2750 t frigate so would this ship had enough speed with two Speys?
And how much power would the RR marien Spey had have in the 70´s ?

The Marine Olympus was originally a Bristol Siddeley proposal, predating the 1966 merger with Rolls Royce. Consider that the Olympus was a mature program, in the correct category, with an assured future due to the sacrosanct Concorde program, and it isn't hard to see why there was a marine derivative. My suspicion is that the definitive versions of the Marine Olympus benefited from the development of the 593 for the Concorde.

In contrast, the Spey was a far less mature program during the mid 1960s, and it is unclear if Roll Royce was even actively pursuing the Marine Olympus after its selection. In many respects, the Marine Spey owed much to the later Tay, which itself was a Spey derivative, and even some aspects of the RB.211 if certain sources are to be believed. So it never was a simple case of a choice between a Marine Olympus and the Marine Spey as the two programs belong to two distinct time periods. Personally, I doubt that a Marine Spey would have been available before the 1980s, even if its development had been a fully funded priority. As it was, the development of the Marine Spey was pushed forward for the Type 23 frigate program, which is why it was fitted to the Type 22 class, with HMS Boxer representing an operation testbed.

In any case, the earliest opportunity for a 4 Marine Spey surface combatant was the Type 43, which fell victim to the Nott defence cuts, and there was no real subsequent opportunity for any subsequent destroyer program with this configuration. Similarly, there was no real opportunity for a small, hypothetical twin Spey surface combatant, as the Type 23 represented the minimum unit of its time period.

This post centers on pure speculation, so it is more suitable to Theoretical and Speculative Projects subforum.
 

Anderman

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Thanks TinWing :) do you know what the performance of the olympus tm1a was, afer wikpedia is was only 15 000 shp for HMS Bristol (Type 82)

http://en.wikipedia.org/wiki/Type_82_destroyer

So if it´s unlike that the Spey could become the RNs LM2500 could it have been the Olympus ?
 

Graeme65

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The aircraft version was used in the Buccaneer and the BAC 111 by the mid 60s and with afterburner in the Phantom by the late 60s, so clearly was not short of development commitment. The Olymous on the other hand was in the TSR2 (cancelled mid 60s) and Concorde,so in a way probably no more advanced. The difference seems to be that Bristol were in the market for the marine version and the RN seem to have been happy to support this. It is likely that the reason the marine Spey waited to the 80s was that this was the first time the RN came up with the requirement.

The Spey SM1A developed 18,770 shp and the more developed SM1C 26,150. The SM1A would have been a good fit for the Bristol (4 of them giving 75,000 shp) and could have made her a little more affordable to run with somewhat lower machinery manning requirements. Had the RN gon for the hi / lo mix they toyed with, two Spey could have powered a Type 23 sized frigate perfectly well. As it happened the move towards the larger much more capable ASW frigates like the Type 22 were a better fit for the historical Olympus (the SM1As cost Brave 1.5 knots) Oddly the four spey arrangement would have served the Invicible better (the four Olympus were downrated to 79,000 hp). Ironically when you consider that the Invicibles would have benefitted from being a lot bigger than they actually were.

In some respects the Spey would have been a very good choice for the RN heading into the 70s as it was the sma eengine that powered all their fast jets. You would really need a ratherdifferent history, perhaps where the navy kept large carriers, as the commonality with the air group historically went by the end of the 70s.
 

Graeme65

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Not really that surprising when you think about it. 100,000 shp plus is in the ballpark for the 30kt Victorious at 35,500 tons which is a lot more than the 19,000 ton Invincible. The cost and design implications for such a powwerful drive train in a relatively small hull cannot have seemed worth it for an ASW carrier. Of course with 20:20 hindsight had they been built in the 35,000 ton range they would have been vastly better post cold war assets, able to field a ballanced airgroup of harriers. Sadly in the late 60s future proofing by making provision for anything approaching significant fixed wing air defence and air strike capability made the then recent decision on CVA01 look questionable.
 

Anderman

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I was surprised because i read on hazegray or wikipedia that the Invicibles had 4 Olympus with about 96000 shp.
 
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lenny100

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Anderman said:
I was surprised because i read on hazegray or wikipedia that the Invicibles had 4 Olympus with about 96000 shp.
that is the rated hp of the engines but due to problems with the gearboxes "Invincable sailed to war in the falklands on one shaft due to gearbox dammage" they were de rated
 

Graeme65

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I knew that Invicible undertook an engine change at sea during the Falklands War cruise but have never heard of gearbox damage.

The four Olympus could develop 112,000 shp and this is often quoted for the class, but the clue is the 28 knots that is also quoted, Hermes could make this on 76,000 shp and was a much bigger ship.
 

TinWing

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Graeme65 said:
I knew that Invicible undertook an engine change at sea during the Falklands War cruise but have never heard of gearbox damage.

The four Olympus could develop 112,000 shp and this is often quoted for the class, but the clue is the 28 knots that is also quoted, Hermes could make this on 76,000 shp and was a much bigger ship.

There are notable differences in hull form and length to beam ratio between Hermes and the Invincible class. For the WWII light fleet carriers, flight deck length was a priority, along with maximizing speed given the constraints of a propulsion plant that was effectively half that of a full fleet carrier. With all of practical, material and fabrication limitations imposed on the Centaur (and earlier Colossus) class carriers, I'd say that the designs were exemplary. I wouldn't say the same about the Invincible class or Ocean.
 

Graeme65

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The design goal would be very different. The Invicibles lean more towards volume within the hull and also very importantly large propellers that rum more quietly. Less optimised towards ultimate speed. That said despite their compromises they are I gather a bit faster than the Centaurs on not much more power.

I wouldn't argue with the quality of the Centaur design in terms of cost to effect, and they would have enjoyed a greater reputation and service life if the performace of aircraft and the subsequent rise in weight and size had been less pronounced in their era.
 
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