The B-2 was developed to perform penetration missions deep into enemy territory.[2] Scaled Composites designed a RCS model for the B-2 aircraft in 1989.[1] It uses curved surfaces to reduce the radar cross-section.[2] It has the radar signature of a flying bird[2] <0.1m^2. The flying wing design combines perfomance and low radar signatures. Due to the particular limitations of flying wings, flow control and advanced control problems are essential. The B-2 motion flight simulator uses Green Hills FORTRAN Compiler.[3] The initial performance goals were a 6000nm un-refueled range with 50000 lbs of payload, an altitude of more than 40000 ft, and high-subsonic speeds.[4] The mission was changed to include terrain-following capabilities which led to the sawtooth trailing edge.[4]
The 6 aircraft in the test program had focused missions up to 1997 when the EMD ended.[4]
| Airframe | Test Focus | Flights | Flight Hours |
|---|---|---|---|
| 1 | Envelope expansion | 81 | 353 |
| 2 | envelop expansion, performance, weapons | 176 | 903 |
| 3 | systems, avionics, TF, OT&E | 262 EMD 334 post EMD | 1401 EMD 1779 Post EMD |
| 4 | Avionics, Systems, Weapons, TF | 226 | 1213 |
| 5 | Climacitc, Weapons | 163 | 849 |
| 6 | TOV&V, Avionics, Weapons | 109 | 566 |
| 18 | Avionics, Systems, Weapons | 455 Post EMD | 669 Post EMD |
Airframe 3 was then the sole test airframe until 2009 when it switched to ship 18 which has been used up to present.[4] There were 58 software drops in the EMD phase.[4] There have been 40 software drops in the 20 years since then.[4] It was the first use of 3D design tools, and it used integrated federated avionics architecture.[4] The Radar of the B-2 initially could not differentiate a rain cloud from a mountainside.[4] The original design had 3 crewmembers, but it was reduced to 2.[4] Deformable wing surfaces were considered, but rejected due to inadequate low-speed control authority and technical readiness concerns.[6] By 1992 thousands of hours of tests had been completed as shown in the table below.[7]
| Test | Hours |
|---|---|
| Wind Tunnel | 20000+ |
| Avionics | 44000+ |
| Flight Controls | 6000+ |
| Human Factors | 16000+ |
A small initial design team allowed for rapid decision making.[8] Extensive CFD analysis was used for minimal reliance on wind tunnel tests for fast design iterations.[8] The initial design phase used a Garabedian-Korn 2D airfoil analysis code and a transonic wing analysis tool GACBOPPE.[8] Software for 3-D Lofting was developed before being used to develop the shape of the B-2.[8] The B-2 Aerodynamics development group became the preliminary lofting group, giving outer mold lines with enough quality for the structures and LO teams to sign-off on the design.[8] When testing the flight controls on the TIFS airplane, a severe PIO was encountered.[9] This turned out to be an artifact that was not representative of the actual landing handling of the B-2.[9] The software laws switch the antennas from the upper to the lower antennas when the weight is off of the wheels.[9]
[[John Cashen]] – Lead designer
[[B-2 Refueling Pitch Controller]]
[[B-2 Off-Nominal Approach Pitch Controller]]
[[B-2 Structure]]
[[B-2 Flight Tests]]
[[GACBOPPE]] – Aerodynamic design tool used in the Development phase.[^8]
[[B-2 Wind Tunnel Models]]
Sources
- [1] “STARGAZER – A unique database on Burt Rutan and his projects!” Accessed: Jan. 02, 2023. [Online]. Available: http://stargazer2006.online.fr/unmanned/pages/b2model.htm
- [2] R. Rodríguez, “Here’s How a 2 Billion Dollars Flying Wing can Disappear from the Radar Screen,” Geek Culture. Accessed: Oct. 17, 2022. [Online]. Available: https://medium.com/geekculture/heres-how-a-2-billion-dollar-flying-wing-can-disappear-from-the-radar-screen-a8e0b9d6cd1a
- [3] “Northrop-Grumman, using Green Hills Software’s MULTI IDE analysis tools&debugger and FORTRAN optimizing embedded compilers.” Accessed: Feb. 17, 2024. [Online]. Available: https://www.ghs.com/customers/northrop.html
- [4] PeninsulaSrsVideos, B-2 Flight Test, (Jul. 07, 2017). Accessed: Jul. 08, 2024. [Online Video]. Available: https://www.youtube.com/watch?v=l-Fo44a5oOQ
- [5] “Aeroservoelastic Analysis of the B-2 Bomber.” Accessed: Jun. 23, 2024. [Online]. Available: https://arc-aiaa-org.colorado.idm.oclc.org/doi/epdf/10.2514/2.2674
- [6] R. T. Britt, J. A. Volk, D. R. Dreim, and K. A. Applewhite, “Aeroservoelastic Characteristics of the B-2 Bomber and Implications for Future Large Aircraft”.
- [7] “B-2 flight test program – An update.” Accessed: Aug. 04, 2024. [Online]. Available: https://arc.aiaa.org/doi/epdf/10.2514/6.1992-4118
- [8 “B-2 aerodynamic design.” Accessed: Aug. 04, 2024. [Online]. Available: https://arc.aiaa.org/doi/epdf/10.2514/6.1990-1802
- [9] Ron Rogers, Test Pilot Remembrance Black World: B-2, Tacit Blue, YF-12A, SR-71, F-117, U-2, (Jan. 14, 2024). Accessed: Aug. 09, 2024. [Online Video]. Available: https://www.youtube.com/watch?v=2w2ziuvvd04
Backlinks
B-2 Spirit
Composite Materials
[[Computational Fluid Dynamics]]
[[Envelope Expansion Flight Tests]]
[[FORTRAN]]
[[Green Hill Software]]
Pilot-Induced Oscillations
[[Radar Cross Section]]