Avro Vulcan B Mk.4

[steelpillow]

Shortly after the successful end to the Falklands War of 2 April - 14 June 1982, what if Britain had decided to retain a Vulcan fleet in front line service?

Still in service with Nos. 44, 50 and 101 Squadrons, the planned and now overdue withdrawal was cancelled. Six would be converted to air refuelling tankers and remain with No.50, while 101 would move over to tanker duties with other types. Several Vulcans were already museum pieces, and a few clapped-out examples would follow. With six to be converted to tankers, what if there were still enough flyable, or repairable, examples to form an operational bomber squadron?

These last were consolidated with No.44 Sqn. Significant refurbishment and updating would be required to maintain the fleet as an effective force, not least new engines to replace the time-expired Olympus 301. One borderline aircraft was handed over to B.Ae for refurbishing as the test and development vehicle. The re-engined variant would need a new designation. The B Mk.3 had once been proposed, but never pursued, so B Mk.4 it would be.



The backstory kinda took over at this point.

Besides the engine replacement, a good many improvements were required. Equipment in short supply, obsolete, or difficult and expensive to maintain, needed to be replaced with more modern equivalents. Since the Vulcan's heyday, all aspects of avionics, and especially electronic warfare, had advanced by leaps and bounds, and the avionics suite would undergo a major uplift, preferably in stages. Aerodynamics had also advanced, notably in the design of the supercritical wing which the Vulcan had pioneered, and in the use of blended wing-body junctions to reduce drag. So some aerodynamic modifications to the airframe would be advisable, alongside any needed to fit the new engines.

As the refurbishment programme got under way, to keep as many of the current fleet as possible flying, the first design decision was the new engine. The old Olympus 301 could produce 21,000 lb. Almost 13 ft (4 m) long and just over 3 ft 6 in (1.1 m) across, it weighed in at 4,000 lb (1,800 kg). But as a pure turbojet, it was poorly matched to low-level missions. A turbofan would bring improved payload-range, but the only comparable engines were civil turbofans with large-diameter fans. Several smaller and lighter American turbofan engines were narrow enough to fit and offered 15-17,000 lb class dry-thrust performance but, without their fuel-hungry afterburners, would the performance hit be unacceptable? Swapping out the avionics for modern solid-state equivalents should save substantially on the electrical power and cooling systems, while aerodynamic refinements should reduce drag by a useful amount. And a lighter fuel load would also help. It would all make for a lighter aeroplane with lower induced drag, but would it be enough? Fears for the inevitable scope creep led to the rejection of this approach.
A brand new design would take too long, so the only option left was an updated turbojet. The Pratt & Whitney PW1120 being developed for the Israeli IAI Lavi fighter was, like the Olympus, a turbojet, but was at least a more efficient modern development and already at an advanced engineering stage. It was lighter and a little narrower than the Olympus, though a few inches longer. Curiously, it had been developed from the core and afterburner of the successful F100 series turbofan, which had however insufficient dry thrust. Meanwhile the Olympus had seen steady supersonic development, first for TSR-2 and later for Concorde. A turbofan derivative had been studied for Concorde (but never pursued), however it would require a wider diameter and would not fit in the existing wing structure. Still, advances such as higher combustion temperatures could provide some improvement in efficiency. Avro approached both P&W and R-R. The American project proved too tied into conflicting requirements and international politics, while R-R were more enthusiastic. They quickly came up with a design combining the original subsonic layout with relevant improvements from the later variants, along with recent materials and existing knowledge. Anything needing additional research was avoided, with a test prototype being built from a mix of spares and off-the-drawing-board new parts. The sole Olympus 600 first ran only two years later, with a little-changed 601 flying in the B Mk.4 development airframe in 1985.

With that settled, the airframe came into focus. Supercritical work on the outer wing had been progressively applied to the Mks 1 and 2, and could be left alone. But the wing-fuselage junction was not area ruled and could do with some refinement. Much had been learned about engine intake geometry, and it would do no harm to apply a little supercritical remodelling to the inner leading edge at the same time. What grew out of these studies was a blended wing root junction, with the upper fuselage cut down just behind the cockpit. The Mk.4 was technically not just a tailless aeroplane but also now a blended wing-body, almost a true flying wing. The blending created a small leading-edge root extension (LERX) faired in above the engine intake, and a smaller fillet back from the trailing edge. The intakes themselves were lowered slightly, partly to make room for the LERX and partly to make better use of the leading-edge compression zone. They were also slightly deepened to increase mass flow at high altitudes, a fix that should really have been implemented for the powerful 301 development of the original Olympus. These changes helped with directional stability, allowing the fin to be clipped a little, while the forward fin extension was angled down to meet the lowered upper decking. With the hardening up of the avionics specification, a decision was also made to make a permanent fixture of the underwing boxes between each pair of engines. They were no longer needed for their original purpose of system cooling, but appear to have been reserved for some kind of secret avionics fit. Whether this was defensive countermeasures, active electronic warfare, or some other role, has never been declassified. Not needing cooling air intakes, they were faired in along the length of the protruding engine tunnels.

Housekeeping avionics - flight, engine, communications and similar systems, were updated piecemeal as occasion demanded. The starting point for the new operations avionics fit was to be that of the Panavia Tornado. However it needed to be better optimised for high-altitude bombing and, because of the Vulcan's vulnerability, improved electronic countermeasures (ECM). This would be at the expense of the Tornado's air interception and precision ground-attack capabilities. Both programmes would run on well into the Mk.4's operational life, with the operational avionics under continual advancement and showing no sign of slowing down, even today.

In another part of the forest, during the mid-eighties B.Ae Dynamics electromagnetic compatibility (EMC) test division at Filton were developing a radiation-absorbent material (RAM) coating for their test chambers, based on a hot-melt powder-coating technology. Besides the binding plastic, the powder incorporated a mix of ferrite, metallic and other classified materials. It comprised two separate layers; the first was diamagnetic-loaded to tailor the magnetic near-field to the conductive base, while the second was dielectric-loaded to tailor the effective electrical resistance to the electromagnetic free field. To apply it, a hot air gun heated the metal base locally, a cold powder blast applied the first layer, which melted and stuck to the hot metal. A second, briefer hot air blast melted the remaining powder ready for the second layer, which was applied as before. Finally, a third hot air blast melted the last of the powder to form a smooth, easy-clean skin with a slight sheen, on the dull side of a semi-matte or eggshell finish.
One of the researchers involved presently gave a presentation at a corporate internal conference, at which one of the engineers from the Vulcan avionics project was present. Rumours were circulating of a secret American radiation-absorbent "stealth" technology. When the Vulcan representative saw his presentation, she immediately realised that this RAM coating performed exactly the same physical function, and could potentially be used as a stealth cloak. She buttonholed him afterwards and began asking questions. She was worried about how classified her idea might become, so she avoided telling him what she wanted it for. That was was just as well, because when she took her idea back to Avro, the B Mk.4 programme went black overnight. All the EMC team would ever see was an immediate stream of questions from her, about specifications and suppliers and the like, and an urgent contract to tailor it for a certain radar band. It took just eight weeks to identify and test a formula which was good to 200 degrees, and tailored to the old Soviet defence radars still in widespread use. Some variation could also be achieved by varying the thicknesses of the coatings. By good luck the coating was a dark grey, with a slight brown tint, while its slight sheen sufficiently antireflective to be about as good as high-speed paint jobs get.
Several months later the test Vulcan, sinister-looking in its dark overcoat, took off for night-time test flights over a selection of radar installations. The cloak was not perfect. Little could be done about the engine intakes and exhaust, or the many straight-edged controls, access panels and the like. Nevertheless, most of the radar operators had no idea they were part of any such test! Only one reported an unusually fast-moving flock of birds, far overhead.
From 1987, all operational Mk.4s would receive this finish overall. The aft sections of the jetpipes, which now also doubled as sound reducers ("silencer" is too strong a word for the Olympus), tended to melt it. And if the threat radar changed significantly, it would most likely have to be stripped and reapplied. Its stealth properties remained even more top secret than the plane; to most of the Vulcan team it was just a new, official European Night Grey (ENG) camouflage. The brown tint was claimed to blend in with the yellow sodium street lamps then widely used. Even when the B-2 eventually arrived, the Americans had yet to crack the waterproofing inherent in powder coating. It is only relatively recently, since they waterproofed the B-2, that the stealth technology behind ENG has been passed on to them in a tit-for-tat exchange. The B Mk.4 remains a dark project to this day. Somebody /may have/ (cough!) spotted one over Area 51 a few nights back: Mysterious 'Dorito-shaped' aircraft spotted flying at night over Area 51.

I have this nice 1:144 Vulcan in my stash, but will need to live to 150 before it rises to the top, hey-ho.

[PR19_Kit]

I hope one of the 'housekeeping' upgrades were three extra ejection seats for the guys in the back.

But I LOVE the whole idea, and I don't care how impractical it may or may not have been in the RW. This is JUST what this Forum is all about. 

[kerick]

I loved this story. I hope someone builds this soon!
It gives me several ideas for the flying wing I was making from the wings of a Victor. The white paint was giving me fits. Something dark and glistening would be cool.

[Dizzyfugu]

Overall EDSG? Worth a try, maybe together with subdued low-viz markings!

[Rheged]

That is a backstory I'd be pleased to have written.  A first rate piece of Whiffery in words.

[The Rat]

LOVE IT! And the fact that the Vulcan engineer is a woman means that the world is proceeding as it should, with inclusivity.

I hope one of the 'housekeeping' upgrades were three extra ejection seats for the guys in the back.

Maybe an escape module like the F-111, but larger.

I was toying with the idea of a Vulcan in an all black scheme, as a night penetrator. Might still do it, but it will be interesting to see your paint idea. 

[steelpillow]

Thanks for the kind words, all.
Few more details coming to light.

Design changes:

• Retractable flight refuelling probe, housed in the starboard LERX.
• Cockpit fairing extended aft, with opening section hinged at the aft cabin bulkhead. Made room for two more ejection seats.
• Engine bay cooling intakes under each engine moved in between the engines, which reduced the effective frontal area of the new inter-engine fairing.

Both these aerodynamic refinements reduced drag and helped raise the critical Mach number. Along with those already mentioned, these allowed the MK.4 to supercruise at around Mach 1.05–1.1 at altitude, without unacceptable drag rise.
3-view in first post updated accordingly.

A modest update on its development and introduction to squadron service:
The early years were fraught. Engines ran out of hours and spares faster than the reawakening production could replace them, with most of the fleet becoming hangar queens by the end of 1982 in order to keep the last two flying. By early 1985 when the first Mk.4 standard airframe arrived, only one aircraft still had an airworthy set of engines. These were transferred to the Mk.4 for type acceptance trials.
Any avionics that required extensive cooling had had to be removed, along with a fair amount of totally obsolete and now useless equipment. However a few gaps were already being plugged, and some urgent reliability issues had been addressed.
Later that year, the first production 401 engine set went to B.Ae for proving trials in their much-modified hack, which had long since officially become the prototype Mk.4.
The next set was delivered to 44 Sqn a couple of months after the last 301 set lost its fourth member and their sole flying Vulcan was grounded. A replacement engine was borrowed from the tanker fleet, with flying resuming a few weeks later. Throughout 1986, 401 engine sets  began arriving with some regularity and were fitted to the waiting airframes before flight testing and delivery. Meanwhile avionics improvements continued to arrive in dribs and drabs, eventually leading to a reduction in crew workload from five to four - so they all now had bang seats.

Codename RAVEN:
Come 1987 and the first stealthy ENG powder-coating jobs, the first truly serviceable B Mk.4s were emerging. Christened by its crews the Ravens, they immediately cornered the market for covert long-range reconnaissance and electronic surveillance missions over an increasingly disoriented Soviet bloc. Development of a bolt-on "recon panel", replacing the bomb bay doors, was put in hand, as realisation dawned that this would be the Raven's primary role from here on in. An equally removable auxiliary fuel tank, in the upper part of the bomb bay, presently followed. The codename RAVEN stuck, and if anything went even blacker than the bomber role. Quite what their roles were in the Balkan and Gulf wars may never be fully known. Much like its small loitering predecessor, the Black Walrus, most of what we think we know about its missions has been gleaned from UFO reports.
All this goes a long way to explaining why, even today, the existence of these planes is officially denied and the programme costs offloaded onto the Chinook, F-35B, and anything else with the political clout to survive the hit.
They have been operational now for nearly 40 years, and 44 Sqn joke that, as long as the Ravens remain, Britain will stay safe.*

* This legend traditionally belongs to the ravens at the Tower of London.

[poru48]

As long as you are updating the Avionics and extending the Cockpit fairing aft, is it possible that the Navigator (Plotter) position becomes redundant? Reduce the crew to four (with their own ejection seats) and you have further reduced overall weight.

[steelpillow]

is it possible that the Navigator (Plotter) position becomes redundant? Reduce the crew to four (with their own ejection seats) and you have further reduced overall weight.

Yes, combining the nav plotter's and nav radar's roles was what I had in mind when I noted the reduction in workload to four. Some nifty electronics (mostly nicked from Air Traffic Control radars) drew the plotted course directly onto the radar display.
There had not been room to give the Air Electronics Officer (AEO) an ejection seat, so he was rather glad to see one vacated at that point! The installation of the ejection seats had increased weight slightly, so the removal of the fifth seat helped balance that out.

[McColm]

If 18 Group had their way the Vulcans would have carried out the  TAPESTRY Operations and probably replaced the Buccaneer in the anti-shipping role. The Searchwater radar installed, you still going to need a tactical navigator and an ECM officer but a four man crew would work.
Engine wise the tried and tested Rolls-Royce Spey but as a whiff why not use the Tornado engines and if the licence was granted to fly at 75 feet at 500 knots. The Sea Eagle anti-ship missiles had a drag element so American Harpoons would have been the best option with recessed air-to-air missiles fitted. A retractable FLIR pod with the later laser snipper sight. I agree with the retractable in-flight refuelling probe.
I can visualise various paint schemes including the underside painted to resemble various fighter aircraft to confuse the enemy.

[PR19_Kit]

I hate to think what the ride would have been like for the crew of an antishipping Vulcan at low level! With that HUGE wing it would have been slung about all over the place with wind gusts, unlike the high wing loaded Buccs who wouldn't even notice a hurricane down that low.

[McColm]

I hate to think what the ride would have been like for the crew of an antishipping Vulcan at low level! With that HUGE wing it would have been slung about all over the place with wind gusts, unlike the high wing loaded Buccs who wouldn't even notice a hurricane down that low.

Low level flying is set at 150 feet for all NATO members but there's a few occasions during the Red Flag exercises held by the Americans that the Vulcan bomber flew lower than this. The USNavy tried to ban them from taking part in the Green Flag exercises as they kept buzzing their aircraft carriers!

[steelpillow]

replaced the Buccaneer in the anti-shipping role.

H'mm. Not sure the wings would fit on an aircraft carrier?

Engine wise the tried and tested Rolls-Royce Spey but as a whiff why not use the Tornado engines

These engines were underpowered for the Vulcan, severely restricting payload-range and max speed. The Spey with afterburner had enough power but, of course, excessive fuel consumption.

A redesigned Olympus with modest bypass around a smaller core was studied, but rejected as it was effectively a new engine and the remaining airframe life would not justify the development cost.

[zenrat]

replaced the Buccaneer in the anti-shipping role.

H'mm. Not sure the wings would fit on an aircraft carrier?

[/quote]

Habakkuk Class?
 

[steelpillow]

Habakkuk Class?

Not sure the jet exhaust would have helped the deck ice.

What we did try to do was to make a bolt-on cross-deck with central steam catapult, to join two more conventional carriers as a massive catamaran. The idea foundered because we were unable to find two carriers of the same class, with the same deck height, never mind moving the bridge on one of them to the port side. A truly fine model that would make! Why oh why is there only one of me?