What if the Northrop B-49 entered operational service.

thorr97

Banned
I always thought that engine layout for that version of the E.555 was drag inducing and airflow starved at anything but level flight. Also having that many engines all packed together and exposed like that seems tailor made for collateral damage if one of them sheds some turbine blades or ingests some .50 cal gunfire.
 
I think or the RB-49 series as reconnaissance platforms, not tasked with nuclear weapons delivery. In neither case is dead-beat yaw stability more than a desirable handling characteristic (the Beech Bonanza and several early jet transports got along without it). For earlier, what we hopefully called 'precision bombing', it was vital. A lengthy rear fuselage extension could fair a thickened center section for carting nukes- it could also include a vertical surface...Why not add a horizontal stabilizer so landing flaps could be hung on the wing? Etc.

The Arado 555 example was kind of simplistic. While the block of engines on the upper wing surface looked awful, recall that most of the air it encountered passed thru it. The failing was that, unlike separated engines, the block wouldn't entrain and energize airflow where lift development could make best use of it + fratricidal engine breakup + limited room for maintenance access.

The Burnelli configuration certainly would work for an unpressurized cargo carrier but, like the flying wing itself, it was specialized and largely bypassed by advances in propulsion with no niche (like the RB) for its time.

Dynasoar
 
I always thought that engine layout for that version of the E.555 was drag inducing and airflow starved at anything but level flight. Also having that many engines all packed together and exposed like that seems tailor made for collateral damage if one of them sheds some turbine blades or ingests some .50 cal gunfire.

I agree, and that one looks even more unstable than the Horton machines, or the B49
 

Glyndwr01

Banned
I wonder if something more like the Avro Vulcan's planform would have provided many of the structural and aerodynamic benefits of a flying wing with better inherent flight stability. A Vulcan like design but with a shorter nose section built in the early 1940's using piston engines with rear facing propellers.
The British tried the.
https://en.wikipedia.org/wiki/Armstrong_Whitworth_A.W.52
images
 
After missiles basically took over the bulk of the strategic mission, "one-way" flight profiles went away, of course there were (and are) manned strategic missions in current SIOP.

Strategic mission yes, unknown for tac nuke deployment mission. It seems that 'one way' flight profile remained for many Soviet/ WP attack aircrafts carrying out tac nuke attacks due to their short combat ranges.
 
AW.52 proved that with sufficient sweep, flying wings could use large Fowler flaps. Fowler flaps mounted near the centre of gravity change pitch very little.
Fowler flaps are so effective that they are installed on most modern airliners.
 
[QUOTE="Dynasoar ..... The Arado 555 example was kind of simplistic. While the block of engines on the upper wing surface looked awful, recall that most of the air it encountered passed thru it. The failing was that, unlike separated engines, the block wouldn't entrain and energize airflow where lift development could make best use of it + fratricidal engine breakup + limited room for maintenance access. ........Dynastar
————————————————————————

Arado 555 illustrates the short-comings of first-generation jet engines.
They were not very powerful so an airplane needed a block/bank of 6 or 8 to produce the same thrust as 1 or 2 modern engines. Grouping them in a block simplified thrust calculations.
The secret problem - with first generation jets - was their thirst. They were not very fuel efficient. This limited their range and forced the invention of air-to-Air refuelling. Despite Hitler’s promises, a piston-powered America bomber could only deliver a small bomb at the end of a one-way trip. While a jet-powered America bomber struggled to deliver the same bomb to Iceland!
 

Glyndwr01

Banned
[QUOTE="Dynasoar ..... The Arado 555 example was kind of simplistic. While the block of engines on the upper wing surface looked awful, recall that most of the air it encountered passed thru it. The failing was that, unlike separated engines, the block wouldn't entrain and energize airflow where lift development could make best use of it + fratricidal engine breakup + limited room for maintenance access. ........Dynastar
————————————————————————

Arado 555 illustrates the short-comings of first-generation jet engines.
They were not very powerful so an airplane needed a block/bank of 6 or 8 to produce the same thrust as 1 or 2 modern engines. Grouping them in a block simplified thrust calculations.
The secret problem - with first generation jets - was their thirst. They were not very fuel efficient. This limited their range and forced the invention of air-to-Air refuelling. Despite Hitler’s promises, a piston-powered America bomber could only deliver a small bomb at the end of a one-way trip. While a jet-powered America bomber struggled to deliver the same bomb to Iceland!
https://interestingengineering.com/...ber-that-almost-brought-the-blitz-to-new-york
Did the JU-390 make it across the Atlantic?

The most interesting part about the JU-390 is that it may have actually been test-flown across the Atlantic.
The 'legend' goes that one of the prototypes, probably the V2, made it safely into American airspace and returned home without being detected.

The flight is supposed to have taken place between Mont-de-Marsan to a point around 20km from New York, and back. This, however, is hotly debated. However, some tantalizing evidence points to a potential sighting in 1944.
 
The flight is supposed to have taken place between Mont-de-Marsan to a point around 20km from New York, and back. This, however, is hotly debated. However, some tantalizing evidence points to a potential sighting in 1944.

1. I doubt it for the simple reason that had it occurred, Hitler would have been told, and Junkers would have got a lot more priority to make more of them.

The Mustache wanted nothing more to be able to hit New York by any kind of hair-brained scheme, including towing a V-2 Rocket behind a U-Boat

2nd, any crew on a mission like that, would have taken pictures. Lots of them, which feeds back into #1
 
I think or the RB-49 series as reconnaissance platforms, not tasked with nuclear weapons delivery. In neither case is dead-beat yaw stability more than a desirable handling characteristic (the Beech Bonanza and several early jet transports got along without it). For earlier, what we hopefully called 'precision bombing', it was vital. A lengthy rear fuselage extension could fair a thickened center section for carting nukes- it could also include a vertical surface...Why not add a horizontal stabilizer so landing flaps could be hung on the wing? Etc.
Dynasoar

I see what you mean. I too wouldn't want to redesign the B-35/49 into a conventional layout. As long as there is an adequate amount of inherent stability so the airplane isn't a deathtrap and can do it's job. You think that the RB-49 with the six top rear mounted jet engines would've be good enough stability wise? I'm inclined to believe you though I bet it would've been a tricky bitch on approach and landing.
 

SsgtC

Banned
https://interestingengineering.com/...ber-that-almost-brought-the-blitz-to-new-york
Did the JU-390 make it across the Atlantic?

The most interesting part about the JU-390 is that it may have actually been test-flown across the Atlantic.
The 'legend' goes that one of the prototypes, probably the V2, made it safely into American airspace and returned home without being detected.

The flight is supposed to have taken place between Mont-de-Marsan to a point around 20km from New York, and back. This, however, is hotly debated. However, some tantalizing evidence points to a potential sighting in 1944.
I highly, highly doubt this. Not only was New York one of, if not the, busiest ports in the world, it was also a major naval base that built everything from Liberty Ships to battleships and aircraft carriers. Long Island was a major USAAF base and was home to Republic Aviation, which was engaged in building hundreds of P-47 fighters a day. And yet nobody ever noticed a massive bomber 12.5 miles away? That's within visual range of New York. Nevermind radar coverage. I find it highly unlikely that not a single radar equipped ship or shore based radar station picked up this aircraft. And even more unlikely would be that they did, then utterly neglected to record it in their logs or ask one of the several Pursuit Wings in the area to send a fighter to check it out.
 
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I highly, highly doubt this. Not only was New York one of, if not the, busiest ports in the world, it was also a major naval base that but everything from Liberty Ships to battleships and aircraft carriers. Long Island was a major USAAF base and was home to Republic Aviation, which was engaged in building hundreds of P-47 fighters a day. And yet nobody ever noticed a massive bomber 12.5 miles away? That's within visual range of New York. Nevermind radar coverage. I find it highly unlikely that not a single radar equipped ship or shore based radar station picked up this aircraft. And even more unlikely would be that they did, then utterly neglected to record it in their logs or ask on of the several Pursuit Wings in the area to send a fighter to check it out.

Another point is that efforts to trace this to German sources come up with a British 1945 interrogation of a Luftwaffe lance corporal. If someone has collaboration from German air force logbooks, post mission reports, mission planning documents, memos, or testimony from the aircrew, or anyone else than a lance gefrieter who claims he heard about it from a buddy.
 
Note the comment specifically said "American Airspace" and the article says the same. The original claim though was "sighted the American coast" and the "20km" from New York is recent too. Also keep in mind the prototypes had only limited armament AND no practical bomb load it wasn't all that much of a 'threat' at that point in the war. Neither would it garner much attention because even if it DID fly all the way to the US as again doing so with a bomb-load and defensive armaments were problematical. "Worse" in Germany's case they'd need to build hundreds of them and they just didn't have the available resources.

As for Northrup's flying wings as I understand it he initially had designed the 'drooping' wingtips to augment stability but like the boom mounted tail these were dropped in order to push up the basic performance. As for the engine mounting idea I can't take credit for it as noted the Germans came up with it first and its been a BWB staple. Even if the idea had occurred to Northrup engineers we need to keep in mind the XB-49 was very much a minimal rebuild of the XB-35 BECAUSE they already had XB-35s to use. Major changes mean a whole new air-frame and the associated costs and it was unlikely the AAF and later AF were going to pay for it.

I'll point out that Jack Northrup was pretty adamant about keeping the flying wing as 'pure' as possible despite the known stability issues. The replacement of the prop-and-piston engines with jets and ducting WAS very straight forward and it was quickly found that adding a 'real' fuselage or expanding the bomb bays dropped performance significantly. Also weight-and-balance issues would have been real problems moving the main weight of the engines aft over the rear part of the wing. Arguably it probably would have gone a long way towards keeping the stability of the propellers, (assuming aerodynamic pylons) but now a lot of weight is towards the rear AND away from the center-line and CG. Moving them inward which would have easily alleviated most of the issue, but again it's major work above and beyond replacing the engines in already designed and tested bays. And again 'drooping' the wingtips or 'end-plates/vertical-stabilizers' on the wing tips and even a tall vertical fin (ala-Vulcan) was suggested but would require a rebuild and probably extensive redesign and with the war ending/ended there was no incentive to do so.

As for air-feed issues this 'can' be a problem for an aircraft that has to do radical maneuvers but bombers were not expected to have a need (or really ability) to perform such maneuvers. Further elevating the intakes out of the direct 'over-wing' flow while it makes them a bit less efficient also greatly reduces the 'shadowing' problems. As well the stability issues of a flying wing were known and there were various means and methods to deal with them as shown in the various designs. Where things got 'interesting' was the transition of propulsion from prop to jet AND every higher speeds.

Randy
 
Randy,

Addressing your concerns about a RB-49 with six J-35 engines atop the rear of the wing. The R-4360 engines, their gearboxes , turbos, extension shafts and contra props were massive,vibrating, torquing monsters. The four in the XB-35, from which the XB-49 and the YRB-49 were modified on the factory floor, weighed, installed, 4080 pounds each. A total of 16,320 pounds. The proposed six J-35 engines weigh 2400 pounds each; six totalling 14,400 pounds. Add nacelles and the weight (and moments) is about the same as the recips. Engine mounts for the smooth running jets-not complex chrome-moly space frames, but largely aluminum sheet doublers riveted to existing ribs and spars, weighing less than the extensive internal wing ducts required for the in-the-wing jets. Compared with the engineering effort required to go from the XB-35 to the XB-49, the above the wing engine modification is- to use a word I've seldom used- trivial.

To summarise, for no net increase in empty weight, we have a more powerful aircraft with greatly enlarged internal fuel tankage, incorporating proven engines, mounted on fins which would improve lateral stability and compared with propellers and underwing jet nacelles, or potentially resonant leading edge duct openings, would further reduce RADAR reflectivity. Also performance enhancing jet energy input to circulation over the wing trailing edge ( boosting the Lambda line integral term which stands for circulation strength in the Kutta-Joukowsky equation: Lift= density (velocity) Lambda) to reduce wing angle of attack and consequently drag at any comparable set of flight conditions.

I can't put a number on the improvement without a lot of non-existent data for exhaust viscous mixing with ambient air etc. To summarize, the proposed mod would be far simpler than the actual factory floor modifications accomplished in the B-35/49 series IOTL and produce an aircraft ideally suited for long range high altitude photo-recon.

Dynasoar
 
Ran into a former associate at the airport on Labor Day. We discussed the Alternate History Forum in general, and the YRB-49A with engines over the wing trailing edge more specifically. He reminded me of an article we both recalled in Aviation Week years ago showing a proposed 737like twin jet transport modified with eight or ten small diameter vaneaxial fans mounted on (above) each of the flaps.

Neither of us recollected how they were to be driven (electrically or hot gas bleed from the main engines) and I've spent some time since looking thru dusty AvWks with no success. Anyone out there?

At least the forum may get a new aviation contributor.

Dynasoar
 
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