ATB: B-2 evolution and competitors

[overscan (PaulMM)]

That seems unlikely, because that would mean downward facing vertical fins. I would imagine the bottom would be extremely flat in a few facets, given the high altitude mission.

 

[Spring]

Are we sure that this puppy is Senior Peg?
ATB had a ferocious RCS spec, so I'd be very surprised to see edge alignments all over the place, let alone a leading-edge kink. Remember that the RCS group at Northrop wanted a continuous, straight, razor-sharp leading edge, and the onluy concession to aerodynamics on the B-2 was the "toothpick" LE, sharp at the nose and tips and blunter at midspan.

My understanding of the evolution from Have Blue to ATA-B and then to Senior Peg was that ATA-A (F-117) was minimum change, ATA-B incorporated some curvature and some rounding of the facet boundaries, and that Senior Peg represented a broadened-out at larger version of ATA-B. The infamous Gene Salvay interview in Wings seems to describe an interim design, but with a sweptforward tail like the Goodall picture.

Some aspects are more critical than other, the leading edge angle for the B-2 is poor for a stealthy concept (30º), so is clear that the Lockheed team wanted a greater leading edge, the problem there is the aerodynamic balance, specially for a subsonic aircraft..., on flying wings the problem is even more critical, since all the mass is pretty forwared, with your wings are sweept back, moving the centre of lift way behind, and this is not just an UAV...we are talking about a big aircraft here.

So at the end, you must use a leading edge of 30º, if you want to fly it.

The lockheed proposal looks like the northrop x-47, guess even them had issues with the original diamond shaped X47

 

[andyl]

i agree that the outer wings looked canted up a bit having studied the initial image for a bit. As to RCS models upside down see image. - i think they get tested from all angles. Plus you need to get a low rcs in certain directions. Approaching from medium altitude the front and underside are important so you need to test from these directions and as the models are huge it's probably easier to mount the radar high and look down than put the model up on a giant pole simply for structual reasons plus a pole on the underside would interfere with results from the more important side for radar returns - the bottom.

 

[andyl]

doing a bit more digging this looks like the original image. Using the car to create a bit of scale gives a wingspan of around 60ft for the model. Searching for b2 rcs model reveals this page http://www.scaled.com/projects/b2model.html about contractor work for the rcs model of the northrop b2. They state a 4/10 scale model was chosen as the best compromise between rcs measurement and structural limitations giving there model a wingspan of 'around 70ft'. Knowing that the Lockheed entry was a bit smaller a wingspan of around 60ft for theirs seems reasonable built to the same scale. From what i have read of Ben Rich's autobiography they competed against northrop on rcs. It would seem a fairly sensible thing to build both models to the same scale to eliminate any testing error and therefore give a direct comparison.

 

[flateric]

Did you ask yourself how many B-2 RCS models were built and did you note the date Scaled was approached to built that one? 1989. So the scale choosen for this one doesn't mean exactly that much earlier ATB models had the same 4/10 scale...

 

[CFE]

As far as the scale of the Goodall aircraft is concerned, has anybody looked at what it scales out to based on the width of the cocpit? I think it's safe to assume it had two-abreast seating. Perhaps the A-6 cockpit is a good reference, but the B-2 cockpit is equally valid.

 

[elmayerle]

Very nice. Does this collection of information include the various configuration studied in 1983 when the low-altitude role was added? There were several evaluated, some more radical changes from the high-altitude version than others, with concepts submitted by both major airframe subcontractors (*grin* I should know, I was there at the time).

 

[flateric]

Evan is back! Holy bananas!

 

[elmayerle]

As I said over on the shif forum, "For some values of 'back'!" Don't have near the time I used to, so....

 

[Orionblamblam]

Does this collection of information include the various configuration studied in 1983 when the low-altitude role was added?

Just what you see, pal.

My sources on the B-2 program are largely what's in the open press, with a few tiny bits from elsewhere. If you have anything you'd care to share...

 

[elmayerle]

Unfortunately, no, I don't have any saved data and Pico had fairly good security on checking outgoing briefcase, attache cases, etc. I do remember one alternate configuration which had the engine inlets in the lower leading edge of the wing, just outboard of the radar units; there was quite an S-duct going back to the engines.

 

[Orionblamblam]

Unfortunately, no, I don't have any saved data and Pico had fairly good security on checking outgoing briefcase, attache cases, etc. I do remember one alternate configuration which had the engine inlets in the lower leading edge of the wing, just outboard of the radar units; there was quite an S-duct going back to the engines.

A reconstruction drawing could be made, though it would be nothign more than "hearsay." What was the planform like? ANy other notable differences?

 

[Matej]

Evan! Nice to see you again.

 

[elmayerle]

Unfortunately, no, I don't have any saved data and Pico had fairly good security on checking outgoing briefcase, attache cases, etc. I do remember one alternate configuration which had the engine inlets in the lower leading edge of the wing, just outboard of the radar units; there was quite an S-duct going back to the engines.

A reconstruction drawing could be made, though it would be nothign more than "hearsay." What was the planform like? ANy other notable differences?

The overall planform was pretty close to what was actually built but the inlets were outboard of the radar units and curved considerably. Naturally, without the inlets, the bulges over the engines were smoothly faired into teh upper surface. The auxiliary intakes and the APU exhaust doors were still on the upper surface, though.


*chuckle* What I really wished I'd saved, though, is a humorous bit one of my co-workers came up with, a course syllabus for a "Masters in Viewgraph Engineering". It was hilarious, given the briefings we sometimes ha prepare for managementd . These days it would be in "Powerpoint Engineering".

 

[Steve Pace]

A late 3-star general once told me that the Lockheed/Rockwell Senior Peg was nothing more than a two-place B-58 sized F-117. That line drawing pretty much proves that. SP

 

[hesham]

Hi,

http://www.flightglobal.com/pdfarchive/view/1991/1991%20-%201428.html

 

[hesham]

Early B-2 artist drawing;

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[hesham]

Hi,

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[overscan (PaulMM)]

Merged topics.

 

[Matej]

I think it was not posted before - two special airframes for B-2 static tests.

 

[Stargazer]

I think it was not posted before - two special airframes for B-2 static tests.

Brilliant! Now if we could get a few quality pics of the RCS pole model (which Scaled Composites worked on) that would be great!

 

[SOC]

I think it was not posted before - two special airframes for B-2 static tests.

One of those was cleaned up and put on display in the USAF Museum. I've always wondered where the other one got off to.

 

[shadeone]

1994 satellite image of the two "iron birds" sitting at palmdale:
[Edit - link dead - Admin]

 

[OM]

1994 satellite image of the two "iron birds" sitting at palmdale:
[Edit - link dead - Admin]

...There use to be a bigger version of this online, but my Google-Fu is failing me on the image searching today :-\ :'( ???

 

[Apollo Leader]

What was the story with the non-standard main gear on the front Iron Bird?

 

[flateric]

means of economy. it just didn't need 'real' MLG to be towed forth and back between shop and test facility

 

[shadeone]

damn.... invisible-defenders b2 page had a ton of pics of the iron birds but even going through archive.org doesnt bring the pictures back. They were taken from a number of books... ill dig through my library soon here.

 

[Matej]

One of them in museum:

https://flic.kr/p/8evwtW

 

[AAAdrone]

I saw that back in 2009 with a JDAM mockup next to it. It's good to know the significance of that mockup considering I used to think it was just a mockup made specifically for the museum.

 

[shadeone]

another shot of the two birds from a James Goodall book:

anyone got any more?

 

[flateric]

anyone got any more?

 

[Stargazer]

Don't know if this has been addressed in the latest versions of Scott's ATB drawings, but when blowing up the Senior Peg image and after reworking it a bit (contrast, light, erasing the pole's shadow...) it seems clear to me that the wing tips look nowhere near like the (otherwise beautiful) drawing that he presented two pages ago.

Any ideas, anyone?

 

[Spook]

This came fromt he rect Av Week article. However, I *know* i've seen this drawing before. I'm looking for a higher resolution version of it... if anyone can point me towrds it, I'd much appreciate it.

Anyway, this was apparently the first sketch of what became the B-2.

Hello,

Will this one help you sir?!

AK

 

[InvisibleDefender]

6 years later and there you go! Not too bad. LOL!

 

[circle-5]

Northrop manufacturer's model of the ATB concept, prior to the B-2 configuration and designation.

 

[flateric]

glimpse on Lockheed's SENIOR PEG performance data according to Northrop's Jim Kinnu:"...it was basically meeting the minimum requirements, a range/payload of 6,000 pounds internal payload, low altitude, 3,000-mile range, refueled for the 6,000-mile mission."

 

[donnage99]

I have a hard time swallowing the idea that lockheed's bid is stealthier than northrop on almost every frequency. Anyone can elaborate on this?

 

[SOC]

I have a hard time swallowing the idea that lockheed's bid is stealthier than northrop on almost every frequency. Anyone can elaborate on this?

This appears to relate back to a quote from Ben Rich stating that (and I'm paraphrasing a bit here as I can't remember the exact wordage) "we beat them on the pole, we beat them in the air, we beat them everywhere."

Problem: Lockheed's ATB loosely resembled an enlarged F-117, again relying on faceting for LO. By this time Northrop had started discovering a different method using continuous curvature which was applied to the BSAX. Based on how this stuff works from a physics standpoint, and having seen the Lockheed design, I find it hard to believe that their ATB was actually stealthier, especially across the board. For one, Northrop had the bigger airplane, so " stealthier than northrop on almost every frequency" is complete BS. The closer you are (i.e. bigger) to wavelength size the better you will be able to counter a long-wavelength radar signal. Metric-range VHF-band: your little centimetric-band-and-smaller optimized facets, edge serrations, etc. have about zero effect. VHF-band isn't anything new, either, so it would've been considered during the ATB program as tons of Soviet-era EW radars operated in those wavelengths. It's only recently that digital signal processing, multiple wavelength systems, and other techniques have made them extremely accurate.

ANYWAY. Given that Ben Rich's statement was, basically, impossible as it would pertain to the ATB designs, I've wondered if he wasn't taken out of context or mixing his platforms, and instead was really comparing the Lockheed and Northrop XST designs. Either way the whole "we beat them in the air" line is amusing as it possibly implies some sort of flight demo for each system.

 

[Orionblamblam]

Given that Ben Rich's statement was, basically, impossible as it would pertain to the ATB designs, I've wondered if he wasn't taken out of context or mixing his platforms...

Or:
1) Just wrong. Had bad data.
2) Dishonest. Salesmanship!

It's not unknown for good managers to say things that Just Ain't So. Look at von Braun and his claims about the A-11 and A-12.

 

[quellish]

Given that Ben Rich's statement was, basically, impossible as it would pertain to the ATB designs, I've wondered if he wasn't taken out of context or mixing his platforms...

Or:
1) Just wrong. Had bad data.
2) Dishonest. Salesmanship!

It's not unknown for good managers to say things that Just Ain't So. Look at von Braun and his claims about the A-11 and A-12.

When it came to the XST, Lockheed did indeed beat Northrop with a much lower signature - in the specific bands that were part of the requirements. Northrop's design, however, was good across a wider range of bands. This was at least partly a result of the fact that Lockheed and Northrop used two very different approaches to software modeling of the radar cross section.

Lockheed had the ATA-B, a larger design based on the ATA-B (what has been seen in a photo mounted on a pole), and their ATB proposal. The two ATA-B designs were heavily influenced by SENIOR TREND. As the ATB requirements evolved it was clear that Lockheed's ATA-B based designs would not be competitive and they ended up with a design that was very much like the Northrop design at the time and of a similar size.