Have Blue

5 August 22, 2024

The Have Blue was a stealth demonstrator aircraft built by Lockheed in a DARPA competition to develop stealthy aircraft. Two demonstrator aircraft were built on a $30M budget. The first Have Blue aircraft was flown in 1977. This demonstrator program became the F-117. It showed that a faceted swept-wing aircraft could have a lower radar cross-section than a conventional aircraft.[3] The flight control system took a lateral accelerometer signal as a surrogate to a sideslip sensor and fed that back into the FCS.[1] This was a problem as asymmetric sideforces from the toed-in engines would create a lateral acceleration even when there was no sideslip.[3] The Have Blue used an early F-16 sidestick.[1] The J-85 engine was used on the prototype aircraft.[4] The main landing gear was taken from the A-10, and the FCS was also from the F-16.[4] The F-16 system was an analog computer.[^6] The ejection seat was from an F-5.[4] The wing was swept back at 72.5 degrees.[4] Two inboard trailing-edge elevons were used for pitch and roll control.[4] ahead of the elevons were 2 upper-mounted and 2 lower-mounted spoilers.[4] The prototypes were painted a camouflage color that would make it hard for observers to determine the exact shape of the aircraft.[4] It had a high landing speed of 160 kts.[4] The aircraft was undetectable to all airborne radar systems except the E-3 AWACS at close range.[4] Ground-based tracking radars could only identify it when it was below the minimum range for the SAMs.[4] Both Have Blue prototypes were lost in accidents.[4] The second prototype aircraft had a double hydraulic failure that rendered it uncontrollable.[6] It had a maximum speed of 600 mph, a wingspan of 22ft, a length of 38ft, height of 7 feet 6 inches, and a weight of 12000 lbs.[4] The vertical tails on the Have blue were mounted on twin booms and canted inward.[4] Unfortunately, this is structurally inefficient and ended up reflecting the heat from the engine exhaust back to the ground.[4] It had highly-swept wings originally had a trailing-edge sweep of 30 degrees, but that would create a large radar return at right angles to the trailing-edge.[5] This was changed to 48 degrees for the trailing edge so that radar signals reflected by the edges would primarily be from the side sectors.[5] The fins were canted so that the edge returns would not intrude into the forward or aft sectors.[5]

[[F-117 Flight Control System]] – Have Blue also used a modified F-16 FCS
[[Have Blue Air Data System]]
[[J-85]]
[[Bill Park]] – test pilot
[[Ken Dyson]] – test pilot
[[Have Blue RAM]]
[[F-117 Low-Observable Design]] – grew from the Have Blue
[[Tacit Blue]] – developed at the same time (at least as radar resistant)
[[Bob Loschke]] – designed flight control system

Sources

Backlinks

[[A-10 Warthog]]
[[Disadvantage of Elevons]]
[[E-3 Awacs]]
[[F-5 Aircraft Family]]
F-14 Wing
[[F-117 Directional Instabilities]]
[[F-117 Nighthawk]]
[[Low Observable Design]]
[[Radar Cross Section]]
Sidestick Controller
[[Superaugmented Disturbance Sensitivities]]
[[Swept Wing]]
[[Tacit Blue]]