PRELIMINARY FLIGHT INFORMATION LETTER - DISCOVERER IV

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP63-00313A000600130041-7
• Release Decision: RIPPUB
• Original Classification: T
• Document Page Count: 7
• Document Creation Date: December 15, 2016
• Document Release Date: September 3, 2003
• Sequence Number: 41
• Publication Date: June 25, 1959
• Content Type: MEMO

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TOP SECRET 86
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Lt. Col. C. G. Mathison
2ND/434 1
DATr 25 June 1959
61?30 I -,.:.r 1 r. 262112
SUBJECT: PRELIMINNART FLIGHT INFGRMATI(:N LETT'_1R - DISCOVERER IV
The second launch countdown for Discoverer I'E` on Pad 5 at Vandenberg Air
Force Base was successfully conducted on 25 June 1959, commencing at OU;S PDT
and culminating in launch at 1547:45, Technical difficulties associated with
1st stage destruct package installation,., 2nd stage beacon verification checks,,
and 2nd stage propellant tanking caused countdown delays totaling approximately
4 1/2 hours.
The liftoff was without incident. Initial report indicates a small pad
fire occurred,., resulting in only a minimum pad damage. (This was the first
launch from Pad 5). Hain engine cutoff was at 158.5 seconds after launch.
However,,, a lower-than-nominal trajectory was recorded by the Hod II radar.
Also a departure azimuth approximately it degrees west of the1751) nominal value
was indicated by preliminary radar tracking information.
. The lower trajectory required an earlier-than-nominal 2nd stage engine
ignition, and as a result the "time.to-fire" computer commanded beacon command
6 at 215 seconds rather than the programmed command 5 (D-timer hold). This
command 6 thus cancelled the backup 20-second D-timer hold as programmed by
the Fairchild, timer, allowing the earliest possible engine ignition. Command
6 (velocity increment to be gained setting) was satisfactorily received and
was held for 13.5 seconds. This duration programmed a velocity to be gained
of 13,090 ft/sec.
A ;second stage engine burning time of approximately 3.16 seconds., 1 second
greater than the prelaunch nominal, was recorded. The ascent trajectory,as
based upon preliminary radar data, was as shown in Figures 1 through 3. Pre-
flight nominal trajectory data are compared with preliminary flight data in
Table 1.
Launch tracking operations were generally satisfactory. Telemetry data
,were obtained at VAFB9 Pt. Mugu, Van Nuys and the telemetry ship stations to
a limit of 573 seconds from launch. However,, the received signals were
reportedly somewhat noisy at all stations. Nevertheless, it is believed that
sufficient data will be available for a complete analysis of vehicle functions.
NRO review(s) completed.
Approved For Release
T%t SECRET
A/ . CIA-RDP63-00313A000600130041-7
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