B-58: Maneuverability, Performance, Versatility

[KJ_Lesnick]

I've got a number of questions regarding the B-58 of which I've had difficulty coming across reliable information online and in books.  It's not that I haven't been able to find information -- I've been able to find loads of data.  The problem is that the data often varies from source to source which raises issues of which ones are right (if any are) and under what circumstance. 

I figure the people here probably might have a better quality of knowledge which I could make use of.  Because of this, I've decided to post this.

I've divided my questions into three areas: Maneuverability, Performance, and Versatility


I: Maneuverability

This has posed a great deal of confusion for me because of the fact that some people have described it as being very maneuverable (almost like a fighter) and others said that it's control surfaces were able to make the plane maneuver well but the fuselage cannot take the strain of it making it very easy to overcontrol and damage the plane.  I'm not sure which is actually true as the first description has been used before, but I've also heard the second one used.

I'm wondering which is true.


II: Performance

This largely comes down to the areas of speed and range.  I've heard so many things about this from so many sources I'm truthfully uncertain which one is factually correct or not.  For this reason, I seek to ask people here what kind of information they have available.

Firstly, when it comes to range I've heard so many different figures which include subsonic range figures that seem to range from about 4,000 on the low end to 8,000 on the upper end.  While the aircraft does have a huge fuel-fraction and the ability to rapidly climb it is arguably conceivable that it could fly very far by rapidly racing up to altitude and then cruising efficiently in the thin air up high.  The problem with this comes down to the fact that

• The listed L/D ratio figures for the B-58 aren't very good and while this could be nonsense, the aircraft's wing-loading was fairly heavy during takeoff at least (105.71 lbs/ft); it's wings were quite thin (3.5% T/C); and aspect ratio was fairly low though it featured a noteworthy conical camber
  
• The J79 was a fairly efficient engine and was said to be one of the first US jet-engines that truly outperformed the designs the British had
  
• A pilot who flew the Avro Vulcan said that fuel consumption figures for the days would have inevitably lead to shorter ranges than the uppermost figures (admittedly the J79 might have been more efficient than the engines his plane used, but the Vulcan was said to have an L/D ratio similar to the B-47 which was quite high)
  

..
As for supersonic range figures I remember seeing a variety of numbers which could potentially have been maximum range while supersonic, or maximum overall range

• Early sources pretty much said the plane was only designed to quickly dash supersonic which is largely untrue
  
• One source I remember said that the aircraft could go around 60-90 minutes supersonic
  
• I've heard figures ranging from 2,000 - 3,000 nm commonly cited
  
• I have also seen some figures of around 4,000 nautical miles and one for around 5,375 or 5,400 nm
  

..
Secondly, when it comes to speed I've got two normal discrepancies here as well as a few other sources which conflict most other sources, but I can't entirely dismiss

• Most sources list a speed of Mach 2.0 - 2.2, and a dash-speed of 2.4
  
• At least one individual I know who served in the Air Force stated that the B-58 was capable of Mach 3 (possibly in a cruise)
  - At least one individual on Secret Projects did suggest rumblings that it could either approach or reach Mach 3 at maximum (indicating a lower cruise-speed)
  - The aircraft could reach a maximum airspeed of at at least 600 KIAS, which at 60,000 feet is a little over Mach 3, depending on air-temperature (and it has exceeded this altitude under various circumstances)
  - There was one flight which was mentioned in a book I have about the B-58 (Jay Miller) where the aircraft went from Seattle to Texas with an average speed of 1,310 mph IIRC (that means it's maximum speed was over 1,310 by definition)
  
• The aircraft has a largely aluminum construction, however it's honeycomb configuration was stated to provide it a higher speed than typical aluminum skin would allow
  - Honeycomb skin is often smoother than regular riveted skin and as a result generates less turbulent flow over it
  - Honeycomb might be able to generate lower temperatures due to having more internal surface area which can reflect heat away (The Germans planned to use an aluminum foam which was able to take unusually high temperatures, and honeycombs can provide insulative properties)
  - Technically it's leading-edge was made of braised honeycomb stainless steel, as were it's trailing edges due to the exhaust which allow the leading-edge temps to be a little higher than the rest of the skin
  - Even if temperature limits prohibited a protracted Mach 3 cruise, it's possible to reach it momentarily (the F-104 did it and survived)
  
• The aircraft was said to not be power-limited
  - It's possible that the cruise speed would still be in the Mach 2 range based on the design of the inlet and fuel efficiency issues (just because you can reach Mach 3 doesn't mean it's easy to reach it)
  - If temperature limits present themselves, that would still restrict what you can do
  

..

III: Versatility

I'm aware the B-58A had a surprising amount of versatility in it due to the weapons-pod design

• There was a proposed pod that actually had a rocket-motor, a guidance system, and movable fins allowing it to act as a cruise missile
  
• There was a proposed pod that had cameras in it for recon purposes, it might have requires some switches and display modifications in the second-cockpit and would have been called the RB-58
  
• There was a single-component pod which was operationally used and carried a 10,000 pound nuclear bomb inside it
  
• There was a twin-component pod which was operationally used and carried a bigger lower-pod that had just fuel in it and would be jettisoned when it ran out; a smaller upper pod would carry a bomb and some fuel (the pod would be kept on until the bomb was dropped whether or not the fuel in the pod ran out)
  
• There was a provision to carry an ALBM
  
• There was a provision to modify an ALBM into an ASAT
  
• There was a special pod made to test the AIM-47
  

Among probably others. The B-58 also had provision for four pylons which could carry 4 x B43 or B61 nuclear bombs

There were proposals (such as the B-58B) that included the ability to carry non-nuclear ordinance as well as other interesting designs including

• A parasite bomber along with a booster
  
• A parasite reconnaissance aircraft along with a booster
  

..
I'm not sure how difficult it would have been for the B-58A to have been designed from the outset or rewired to be able to deliver either conventional or nuclear ordinance.  The USAF wouldn't have done it as their mentality at the time was "We'll never fight a conventional war again" -- evidently whoever said that hadn't been paying attention to events past 1945.

Regardless, the ability to just concoct new weapons pod designs to be able to carry them probably wouldn't be all that difficult to do, and considering the size of the GAR-9, It would not surprise me terribly if a pod similar to the single-component pod could carry 4-6 1,000 pounds of bombs inside it.  I'm unsure how accurate the weapons system was for such a delivery, but IIRC it's CEP was about 1,500 feet (I could be wrong here).  This isn't so good for conventional bombing but I'm looking at the types of bombs used on the B-58 -- they were like beer-kegs, and while beer-kegs are great for many things, they aren't great for aerodynamics.  I'm wondering if more streamlined bombs were dropped out they'd be more accurate.

I don't know by how much but that would be a good idea.

[Madoc]

This might be of some help...

Operation Bulls Eye (low level Hustler)

Convair very much explored low level missions for their bird.  The USAF even worked up a B-58 for pathfinder missions in Vietnam.  All at very low level and very high speeds.

[sandiego89]

Well that is a lot to cover.  A few comments.

The Miller book is an excellent source

Maneuverabilty. I think it is best to say it was very nimble for a bomber, but you are correct it was not stresed for fighter like G-forces.  Never intended to be a dog-fighter.  Challenging and had the handling traits of a delta wing.  Pilots generally loved being part of the B-58 force. Big change from pilots transitioning from the B-47/B-50/B-36, so in that regard they would indeed likely call it "fighter like"

Performance.

-Range. Range is always highly depandant on the profile flown.  The max range figures you have found are likely at best efficiency, high.  8,000 sounds way too high.  The figures around 4,000 are more realistic. 

-Speed. Would not call it a MACH 3 aircraft.  While unique atmospheric conditions or a brief full power attempt might get it close, I would say the sources of citing low to mid MACH 2 are more realistic. This could be sustained for some time. 

- Showed excellent low speed penetration, although not initially designed for it (like what was found with the F-105).  All that power helps to go fast and low.  The link from madoc is a good source.

- Versatilty. Lots of proposals, and lots of Whif potential.  The proposal for Australia (in Millers book) is a good bet for modelling a conventional B-58.  This proposal was for a stripped down B-58 with conventional weapon racks on the wing roots. Yes the pod could give you all kinds of options for other bombs or missiles.  You could also hang large conventional bombs (2,000 pounders?) on the 4 nuclear weapon stations where the B-43's went, make a pod with a bomb bay, or hang some weapons on the smaller upper componant pod.  Think you should keep some sort of pod- you need the fuel. 

Yes the CEP will go down with more stramlined bombs and lower level delivery.  In the orginal nuclear role, "close enough" was indeed close enough. 


   

[Librarian]

Not sure if this is any help, and I cannot prove it either way, but in the Eighties I got into a chat at one of those airshows with an F-111 ordnance guy on the flightline who seemed to have made a history of his charge a lifelong hobby. He told me that the reason the F-111 fleet had different MERs to other USAF aircraft was that the company (GD being an offshoot of Convair) had designed the MERs to fit on the four external hardpoints of the B-58. They were then carried over to the F-111 program. If this is erroneus please forgive me, just thought it was interesting and it was from a man who really knew his stuff.

[KJ_Lesnick]

Madoc

This might be of some help...

Fascinating, I'm surprised they'd only carry 3,000 pounds of bombs considering their normal payload was 10,000. 


San Diego 89

Maneuverabilty. I think it is best to say it was very nimble for a bomber, but you are correct it was not stresed for fighter like G-forces.

I assume most bombers could pull around 2.5-3.5 x 1.5g (normal safe g-load 2.5 to 3.5 with a safety margin 1.5 times that); so I assume this plane was like 4.0-4.5 x 1.5g

I'd assume it's large control surfaces made it possible to rapidly build up to maximum g-load faster than most typical bombers as well.

Never intended to be a dog-fighter.

I never said it was intended to dogfight, but I had heard it's agility was fighter-like which I figured would have been used defensively to escape attack so as to allow it to destroy it's target.

If I recall correctly the general maximum g-load forces for fighters of the time were generally listed somewhere between 5.33 and 7.33 g

Range is always highly depandant on the profile flown.

I was assuming a subsonic cruise profile of some sort for a combat mission.

8,000 sounds way too high.

Considering the listed L/D figures, even with a higher T/W ratio and lower SFC I'd be inclined to agree. 

Admittedly L/D figures (B-58) might be higher than listed; the Avro Vulcan might have a higher than listed range

Would not call it a MACH 3 aircraft.

Does a "mach 3" aircraft mean it could cruise at that speed or just touch it a couple minutes?

I would say the sources of citing low to mid MACH 2 are more realistic.

My question is, would you need a speed of

• Mach 2.2
  
• Mach 2.4
  
• Somewhere between Mach 2.4-3.0
  
• Mach 3.0
  

To be able to fly from Seattle to Carswell in 70 minutes?

This was done in 10/15/59, and was mentioned in Jay Miller's book (p.50).

This could be sustained for some time.

I assume this would be somewhere between 1 and 2 hrs?

Showed excellent low speed penetration

The specification called for 630 KIAS (Mach 0.95) at low-altitude and penetration of 1200 nm; the testing shown in the video averaged 610 KIAS (Mach 0.92) for 1220 nm.

Interestingly I'm not sure if it was capable of supersonic speeds at low altitudes.  Theoretically it should be, but there are potential issues involving

• Drag: Air is thick at low altitude compared to up high, once drag reaches the same as the thrust acceleration ceases and you max out.
  
• Trim: C/L shifts aft as you go supersonic; the more lift you have, the more nose-down movement it imparts when it shifts back; admittedly more air over the control surfaces does increase their effectiveness too
  
• Airspeed: The plane was clearly good to a little over 600 knots (not sure how many g's it could pull at that speed), but I'm unsure how much more it could fly at, and how much maneuvering ability it would have at those speeds
  
• Gust response: The aircraft had a low aspect-ratio wing which is conducive to low gust-response; but as the weight drops, the wing-loading would go from heavy to light (wing-loading factors into gust response too) and if the speed were increased significantly, gust response could impose a variety of limits (it would place a greater limit on top speed, and affect maneuvering)
  

..
Looking at the proposals, the best idea seems to be carrying a bunch of conventional bombs in the pod from performance/range standpoint though I'm uncertain how many bombs could be carried inside the pod.

As for external loads

• The 4 x B-43's carried externally caused substantial range penalty at altitude; 4 x 2000 lb conventional ordinance would be practical for more traditional missions and aerial refueling could allow certain missions in places like Vietnam
  
• The RAAF proposal had 12 hard-points for what appeared to be 1000 pound dumb-bombs which might still allow full speed, but would severely shorten ranges at high-speed; at low altitude, I'd rather use the F-111
  

..

Yes the CEP will go down with more stramlined bombs and lower level delivery.

What CEP did the B-58A have to begin with?

In the orginal nuclear role, "close enough" was indeed close enough.

During the first nuclear bomb deployments (8/6 and 8/9 1945), the Norden Bombsight was used (This probably had to do with the fact that it was procedural and for the fact that we might not have wanted anybody to think it was an unusual mission); post WW2 the use of radar-directed bombsights were used and the CEP was around 3,000 feet; as time went on the accuracy requirements were reduced to 1,500 feet due to hardened locations.


Librarian

Not sure if this is any help, and I cannot prove it either way, but in the Eighties I got into a chat at one of those airshows with an F-111 ordnance guy on the flightline who seemed to have made a history of his charge a lifelong hobby. He told me that the reason the F-111 fleet had different MERs to other USAF aircraft was that the company (GD being an offshoot of Convair) had designed the MERs to fit on the four external hardpoints of the B-58. They were then carried over to the F-111 program.

While we're operating on rumor here: How many bombs could each MER carry?

[Librarian]

Someone with far better knowledge should answer this one. I love what-if but really don't want to stray down this path without expertise. I vaguely remember something about them being able to withstand greater stress loads....not sure if this is aerodynamic or weight. My brother in law is ex-USAF (scored a direct hit on a flock of sheep during Desert Storm cause of problems they were experiencing with their new F-15E's pods at night...thought it was a military target!!) and he delved into Op. Bullseye for me through his contacts but drew a complete blank. Still very hush hush. Probably something to do with the possibility of a nuclear bomber being sent to such a sensitive theatre .

[KJ_Lesnick]

San Diego 89

Did you get my previous messages?


Librarian

Oh well...

[KJ_Lesnick]

I just thought of something...

The B-58 didn't really need that tailgun did it?