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Alternative history powerplants

zen

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What happens if....

Bristol builds the BE.30 or 33?
Or AS the P.151?
Or RR one of the RB.106 versions?
Maybe the small RB.126 or the large RB.128

What happens if the Buccaneer flies with the BE.33 instead of the Gyron Junior?
No Spey for the mk2 I might suggest.

What happens if India buys the BE.30 for the Marut?

Might the Gnat mkV get further with one of these?

Might the Lightning be so fitted?

What happens if the F4 is still chosen but instead of the Spey it gets the Thames?
Higher velocity exhaust means a much higher and faster flying F4.

Could we see F104 or F8 with one of these?
Had the bigger Thames versions been built, would this be chosen by Avro Canada for the Arrow?
Without the costs of getting Orenda to develop the Irequois?

Would we see these developed into maritime GT's?
Ships powered by RB.128 instead of Olympus?
Or Tynes replaced by BE.30?

How would it effect the process of Concord? Would it fly with RB.128s?

How might turbofans develop if these new cores exist?
A bypass BE.30 or RB.106 for example.

Let's add a real wildcard in. What happens if a test article is built using EE's ramjet wing?
Could we see a missile development?
 
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sferrin

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"Could we see F104 or F8 with one of these? "

The F-8 actually ended up with the more powerful J75 in the form of the XF8U-3.

"Higher velocity exhaust means a much higher and faster flying F4. "

Not necessarily. The F100-PW-229 has a much higher exhaust velocity than the F110-GE-129 but apparently the latter smokes the former performance wise at all altitudes & speeds. (No idea why.)
 

Archibald

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I love the Marut, cute little pointy jet fighter that never got a viable powerplant in the first place.

J79 and Avon are basically same diameter / size / length / weight. And much smaller than the J57which was bulky - an older generation.

A case could be make that, the J57 stuck into the Crusader... rear end was so large and heavy, the resulting large engine bay & fuselage diameter could have sheltered
- the Lighting and Draken Avon derivatives that flew in the 60's
- plus the improved variants that were cancelled in the mid-50's - RB.106 / 122 /128.

The Crusader III traded a J57 for a J75 but it was essentially a brand new aircraft, the Crusader name was a ploy from Vought to reassure / fool the USN by telling them "oh yes, of course, it a Crusader derivative".
The real loss as far as Crusader derivatives go, was the V-1000 from the late 60's. Considering how the F-104, Skylancer and Super Tiger ruled the skies after trading their XF-104 - Tiger > J65s and Skyray > J57 for the J79, the Crusader would have been boosted by such swap, too.
And then once again, where a J79 fits, an Avon fits, too. Hmmm RB.146 powered Crusader... an Avon powered Phantom, now that's an idea that make so much sense, it is not surprising it was NEVER considered.

Swapping Avons for J79s in a Phantom airframe might be easier than the OTL Spey monstrosity. As far as thrust goes, late Avon and J79 were 7800 kgp when poor Atar 9K50 was barely 7200 kgp. It is no surprise Tonton Marcel hated SNECMA and proposed a boatload of Avon and J79 powered Mirages.

Note that in 1963 Australia was proposed an Atar-Phantom (Model 98DX according to Joe Baugher) for the sake of commonality with their Mirage III-O. some years before in 1960-61 and in a reverse move, Dassault actually flew an Avon-Mirage !
Funnily enough, had the Avon-Mirage been picked by the RAAF, then the Phantom proposal would have to eat Avons, too, ot Atars.
I kind of like these hybrids airframe-engines that never were.
 
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zen

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In context of a comparison between turbojets and turbofans, the fan air is slower and cooler, which means that while it's thrust is potentially equal to a turbojet, the lower velocity /temperature results in less effective power at higher altitudes and speeds.
Thus while the Spey was more efficient at low altitude and consequently lower speeds it's performance at altitude suffered as it did at high speed.
See for instance the debacle of the Spey offering to the P1154.

Hence if instead of the Spey the UK fitted the F4 with the Thames, due to the higher temperature and velocity of the exhaust, performance would be superior. Not just to the Spey, but compared to the J79.
Result would be an F4 which can take off with dry thrust at low weights from Ark Royal, higher rates of climb (due to the lower fall off of power at higher altitudes) and potentially higher speeds.
Though on this last point, the F4 was limited to mach 1.9 in non-all-out-war due to the thermal limitations of the cockpit canopy transparencies. Mach 2+ speed meant replacing the transparencies.
However the higher performance, would be felt in accelerations at all altitudes.

While the Thames was predicted to have better s.f.c figures than the Avon. It's reasonable to presume it's not much worse than the Spey which wasn't that much better than a turbojet due to it's low bypass ratio.

The only real world comparable engine to the Thames, is the Orenda Irequois.
 

zen

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I agree that it would have been simpler to opt for a licensed Avon Crusader, with say three 30mm ADEN cannon, AI.23 and Firestreak.
This could then be upgraded with Thames, improved AI.23 and Red Top.
And in turn rather than replace, just upgrade further the AI set and missiles.
 

Archibald

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I don't know how large were the Red Top and Firestreak but the French Crusaders could carry R530 on the sidewinders fuselage pylons.
 
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pathology_doc

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Red Top is not that much smaller than Sparrow, in terms of body diameter and overall wingspan, though it is much lighter - 330lb as opposed to 450-500 (depending on variant). The difference is that Red Top's major fins are not the control surfaces; those are at the tail, and are much smaller. Sparrow's fins are of roughly identical size fore and aft, and the actuator surfaces are the FORWARD wings.
 

apparition13

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The real killer engine here is the RB.106, and I think the biggest powerplant mistake (with the Orenda Iroquois second) since it was being designed as a drop in replacement for the Avon. That should put it at about a length of 126 in (3,200 mm), a diameter of 35.7 in (907 mm) and a weight of 2,890 lb (1,310 kg)*, but with significantly more thrust at 15,000 lbs dry and 20,750 wet.

For comparison, the J79 is longer and wider, and 1000 pounds or so heavier, the J57 is also longer and wider, but 500 or so pounds lighter, with the J52 is a little shorter, slightly wider, and also around 500 pounds lighter, and the Atar much longer, a little wider, and around 300 pounds heavier.

It has 3000 lbs of dry thrust on the US engines and 5500 or so on the Atar, and about the same 3000 lb advantage in afterburner thrust on the J79 and J57, while it has 7500 on the Atar.

Most of the Avon birds are out of production, but as a retrofit would improve all of their performances (imagine a CAC Sabre with 15k thrust), and the J35 at least is still being built.

Both the A-4 and A-6 (J52) would benefit at takeoff and for egress and defensive maneuvering. With the AB the A-4 would be above unity at it's combat weight, and an already pretty good dogfighter might become a great one.

But the killer gains would be for the J79 and Atar aircraft. Between the weight reduction and thrust increases the F-4, F-104, F11-1F Supertiger (the timing is right for an export version using the RB.106), and Mirage III would all be right at or just above a 1-1 thrust to weight ratio.

The Supertiger would now be a much more attractive fighter, especially for carrier ops, and may be attractive to the UK and France in that role, and perhaps for the US Navy as a small carrier replacement for the F-8. A CL1200 like F104 would still be around 1-1. Although I think both scenarios are somewhat unlikely

The already capable Mirage III would be a Boyd and Sprey dream come true, and would demonstrate that in '67.

But the biggest effect would be with the F-4, since that much extra power would make it a much better dogfighter, and I think would have a good possibility of keeping the F-X program that led to the F-15 to it's earlier incarnation of a 60k pounds and variable sweep strike-fighter, the Republic FX-6 being a an example, given the F-4 would be a more capable air superiority fighter.

If the fighter mafia complained, Mirage III or afterburning A-4s should placate them.


* figures from wiki, so grain of salt, especially regarding diameters.
 

zen

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I think the Avon was 37" diameter, but otherwise yes.
The reheat section is very close to those of the Spey. Likely RR just ported over the work on such reheat units.
The RB.106 ought to be lighter than the Avon due to much higher use of titanium. So the closest real figures would come from scaling the Irequois down a bit.
 

zen

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So had any or all of the trio of RB.123, P.151 or BE.30 gone ahead from '54, they would exert an enormous influence on decisions and designs.
In essence they would figure not just in the NA.39 winner B.103 that became the Buccaneer, but would be the chosen powerplants of the Bristol T.188 research machine, the P.177 or Avro 720 mixed powerplant fighter and at least AWA's and DH's submissions to F.155.
As the P.151 alreawdy figured in the Avro 726, we can also see them likely used instead of Gyron juniors in the 729.

In multiples they would likely crop up in the supersonic recce/bomber studies.

Such engines certain would be explored both for retrofit to the likes of the Hunter, Sea Vixen, Scimitar and Canberra as they would figure in variants of new designs.
As I've said elsewhere, had Hawkers used a pair of these on a P1103 study, this would rightly fall into ideal carrier fighter territory.
These would certainly fit into the Lightning, and rather like the later RB.153 so studied, offset the lower thrust with lower weight and easier installation/access for maintenance, to no appreciable drop in performance.

Had HAL used such in the Marut it would certainly drive the machine to the desired speeds and as a consequence encourage India to fund it's further development.

These would also be a prime option for the later supersonic trainer.

They also fit into the size to power category used for Vickers OR.346 studies, such as the Type 581 group.
 

steelpillow

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What happens if the F4 is still chosen but instead of the Spey it gets the Thames?
Well the Speys hanging out the back caused it a real problem with the sound barrier. The engine change would obviously bring with it a Thames Ba... >mfff!< [gurgle!] ... "come along quietly now, Sir"....:D
 

Grey Havoc

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If Rolls-Royce had been allowed to proceed with their 1964 turbo-ramjet proposal, it could have opened up even more possibilities, especially in the areas of strategic reconnaissance & sub-strategic strike.
 
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pathology_doc

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Let's take this thread in another direction - what would have happened if RR had actually made the Vulture work, and Napier had not struggled so much with the Sabre?

Should RR have forgotten about ever starting the Vulture and just gone with the R engine/Griffon from the start? IIRC the Peregrine was never the finest aero engine in history; bolting two of them together (which is what I understand the Vulture to be) could only ever have been a disaster in the making.
 
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Nick Sumner

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Let's take this thread in another direction - what would have happened if RR had actually made the Vulture work, and Napier had not struggled so much with the Sabre?

Should RR have forgotten about ever starting the Vulture and just gone with the R engine/Griffon from the start? IIRC the Peregrine was never the finest aero engine in history; bolting two of them together (which is what I understand the Vulture to be) could only ever have been a disaster in the making.
IMHO, the Vulture, or developments thereof could have been very fine engines. The Vulture used Peregrine cylinders, yes, but the spacing on the crank was the same as Merlin, suggesting Merlin cylinders could have been used in later versions. This would give a displacement jump from 42 to 54L . RR characteristically pushed development with incremental changes such as raising boost and RPM which took Merlin from being a 900hp engine (Merlin C) to a 2400 + hp engine (RM17SM development stage). Also, the fix for Vulture (a balance tube to ensure even lubrication IIRC) wasn't even that tricky, they just perfected it after official interest in the vulture had ceased and they'd bolted the supercharger on the back of a Merlin anyway.
 
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