Rutan's design philosophy and composites expertise were obvious assets for classified stealth programs...

The only known photo of the B-2 RCS model on its pole.

Did Scaled built a B-2 demonstrator?

Back in 1984-85, when one knew the Advanced Tactical Bomber (ATB) existed, but before anything had been seen in public, there were rumors floating around that a scaled-down, proof-of-concept version of the ATB had flown. The rumors even showed up in an article in an industry magazine. As Burt Rutan was known to have worked for Northrop at that time, some suspected that Scaled Composites had built it. Famous UFO observer Steve Douglass even videoed the mini B-2 during the Roving Sands operation, and it was also seen near Groom Lake. Even if Scaled without a doubt has the capability to produce Very Low Observable (VLO) aircraft, and though such a contract surely would be in line with Rutan's involvement in scaled-down demonstrators for Fairchild or Beech, no scaled-down demonstrator has been officially revealed yet.


Type: scale pole model for Northrop's Advanced Tactical Bomber



Powerplant: not powered (non-flying)

Significant date: 1989

Scaled Composites was involved with the B-2's development, as was revealed a few years ago when the company published on their first website the picture of a 40% scale Radar Cross Section (RCS) model of the B-2. In 1989 Scaled Composites was approached by the Northrop Corporation for the structural design and fabrication of an RCS model of the B-2 aircraft, such as the ones that had existed for the Northrop XST contender back in 1975. RCS models are how designers determine the visibility of a craft to radar. They don't have to build it as large as the final product, just the same shape. The size of the model is important for the radio frequency being modeled, for instance, if someone wanted to determine the RCS of a B-2 bomber at 10 GHz, but didn't'have an RF darkroom that big, they would, for example, make a 1/5 scale model and scale of the frequency to 50 GHz.

According to Scaled Composites, there was considerable concern over making a large enough RCS model to ensure accurate full scale fidelity while trying to remain within the weight and gust load limits of the measuring facility. A 4/10 scale model (with a resulting wingspan of about 70 ft) was believed to be the optimum size for accurate measurement. The model would have to be disassembled into sections for crating and shipment from the fabrication facility to the test site, and would have to be easily reassembled on site while maintaining the step and gap tolerances required for testing. The model would also require representative engine inlets and outlets and top and bottom rotator assemblies. Scaled elected to use its proven sandwich panel structural arrangement with carbon fiber/epoxy skins and PVC foam cores, virtually identical to a manned aircraft. The use of sandwich panels provided extremely stiff outside skins, which accurately maintain their contours, even when exposed to personnel walking loads.

Northrop teamed-up with Boeing and LTV for the ATB contract, competing with the equally capable team of Lockheed and Rockwell. These were ideal teams from the perspective of experience. Lockheed of course was the pioneer developer of the first stealth fighter, and Rockwell was the leading bomber developer of the last two decades. Northrop also benefited from Boeing's long experience with bombers and its vast knowledge of large-aircraft development. Its lack of experience in supersonic fighter and bomber development was, of course, irrelevant, since the stealth bomber would be subsonic. In addition, both Boeing and LTV were industry leaders in the design and manufacture of composite materials, particularly in the area of large load-bearing structures.As in the case of the XST several years earlier, the Air Force organized a "shoot-out" between models of the two competing designs in May 1981 at a radar range to determine which had the lower RCS. The Air Force also conducted wind-tunnel tests to determine lift-to-drag ratios to calculate potential range.

In October, the Air Force formally awarded the ATB development contract to Northrop. Ben Rich of Lockheed claims that his company's design tested out with a lower RCS. However, the Lockheed proposal called for a considerably smaller aircraft than the Northrop submission, with inferior range and payload capabilities. Northrop's greater experience in directly related design and technology areas may have been the key to its victory in the competition. As one published account notes, developing the ATB bomber entailed significant technological risks relating to the aircraft's "complex curvatures, exotic materials, and other stealth methods." Unknown to Lockheed in 1981, Northrop may have already been flying its prototype THAP spanloader for many months at the time it won the ATB competition.

With regard to internal structure, the RCS model was basically a shell, as it contained no engine(s), no avionics, no radar, no cockpit, and so forth, but metallic materials were inserted to represent various components, such as sheet metal discs to represent the compressor faces, in the engine nacelles, which was the area of most concern. Inspections showed the model to be well within the contour, wave and step and gap tolerances. The complete model structure weighed 6,700 lb, which was considerably under the weight goal. This entire effort was accomplished on schedule and at approximately 2/3 of the original predicted budget on a CPFF contract.

Scaled was given a first-ever Northrop vendor award for this effort. Although this was Scaled's first experience in RCS model fabrication, they found that their standard aircraft fabrication methods were ideally suited to these special requirements; this also gave Scaled an excellent opportunity to develop its capabilities in a technically demanding specialty. The company also learned that LO techniques are not necessarily cost drivers; their basic structural approach naturally results in very accurate, smooth surfaces, with excellent step, gap, and wave performance.

A black B-2 model, looking to be approximately 1/5 scale, has recently been spotted in derelict state in the fenced-in storage area of the museum (north) at Edwards AFB. "I was in this storage area back in April" says David Lednicer. The guy escorting me told me that it was the Scaled RCS model." So it seems the mystery is solved, except the size of this model doesn't match the reported 4/10 scale of the original pole model...

Population: 1

Main sources:
- Scaled Composites official website
- Bomber R&D Since 1945 by Mark A. Lorell
- Skunk Works Digest
- Human Engineered Flying Triangles at

A smaller B-2 model currently sitting on a pole.

The Delta Sigma Corporation

The little-known DSC is a subcontractor that has built several ogive pylons for target positioning on RCS test ranges. Two steel pylons and AZ over EL positioners designed and built by DSC are used for the B-2 Spirit Bomber and other vehicles for depot level repairs at Hill AFB. Later, in 1995, DSC fabricated an 8,000 pound capacity steel pylon for Northrop Grumman, used for VHF through microwave frequencies (see picture).

In 1995 DSC also delivered an 11 foot pylon and positioner to Mission Research Corp. in Dayton, Ohio. This is a steel pylon used in an anechoic chamber. The design goal was to make the positioner as small as possible while being able to support a 500 load tilted at 30 degrees and maintain a consistent velocity with an off-CG model or test fixture. This positioner has the motors mounted inside the pylon, so the rotator is only mechanical – no motors.

In 1995 and ’96 the company delivered four fiberglass ogive pylons to the USAF to support calibration targets for the Diagnostic Imaging Radar project. Each pylon included an elliptical shaped calibration target and a 2-axis target positioner and controller. These pylons are built to be easily man portable, yet withstand 100 mph winds without damage.

Visit the Delta Sigma Corporation website