Black Knight - BK15

BK15 was a re-entry physics experiment but limited by the availability of' ground instrumentation on the range at the time, i.e. the "Gaslight" project equipment and not the more sophisticated "Dazzle" project equipment.

A single stage vehicle was fitted with a separating uninstrumented 36 inch diameter copper sphere (the first pure metal head used). The object was to achieve re-entry of the sphere in advance of and well separated from the main body, to provide spatial resolution for ground instruments. This was to be done by turning the vehicle over in the yaw plane after engine burn-out and separating and pushing the head vertically downwards away from the body when it had turned through 180o.

A sabot containing thrust units was used to push the head away; the sabot itself was to have remained attached to the body by a lanyard.

Subsidiary upper atmosphere experiments were also carried out and further data obtained on Gamma 201 engine performance and propellant usage. It was also intended to test for the first time an "automatic pilot" in the ground guidance system. The vehicle was loaded correctly, the utilisation of propellant was efficient and the performance of the motor was excellent. A head re-entry velocity of 11,600 ft/sec was achieved at 200,000 feet.

Due to guidance telescope tracking difficulties the "automatic pilot" was not introduced during flight as intended. Telemetry was very good and measurements were made in the upper atmosphere by the Cerenkov scintillation counter, the Sporadic E probe and in the Faraday Rotation experiment. The vehicle turnover and head separation devices worked but the timing of the latter was incorrect; the head was separated before the vehicle had turned through 180o.

The lanyard failed to hold the sabot to the body and the sabot therefore accompanied the head. The re-entry of the body and sabot was recorded by the Baker Nunn camera. The re-entry of the head was not recorded by any ground instrument nor was it seen by any observer.

This in itself is a significant result since it confirms the prediction that, because of the absence of ablation products and other contaminants in its wake, the re-entry into the atmosphere of a puce copper head should be a target difficult to detect by optical means.

The sphere was recovered and, as expected, there was no heat discolourisation of the surface; the maximum surface temperature did not exceed 350°C during re-entry.

Number Stages Date local
time Empty
wt [lbs] HTP
[lbs] Kerosene
[lbs} All up
wt [lbs] Burn-out
time [s] Apogee
miles

15 1 1 5 62 22.43 1 554 10 620 1 274 13 448 155.1 494