dawei - 8/6/2007 10:30 AM
Could someone help me know the difference between "droop Zaragoza (109%) " and "1E OPS-3 Zaragoza (109%)? I am guessing ops-3 means an intact abort to the runway and "droop" means a bailout scenario? Thanks in advance for the help.
Well here is the definition straight from the Flight Rules...more than you wanted to know...If this doesn' help any I will try and provide a less criptic version after launch.
e. SINGLE ENGINE (PRIME TAL - 109) (E.G., SINGLE ENGINE
BEN GUERIR - 109):
THIS BOUNDARY REPRESENTS THE EARLIEST TIME AFTER
WHICH AUTO GUIDANCE WILL ACHIEVE THE RANGE-VELOCITY
TARGETS AT MECO FOR THE PRIME SITE. ASSUMPTIONS:
PROTECTS 2-SIGMA MPS FPR, PROTECTS AT LEAST ZEROSIGMA
ENTRY DISPERSIONS, AND MAX THROTTLE. ®[120894-1741 ]
This boundary is different from the single engine TAL boundaries for the in-plane cases because it assumes max throttles versus nominal throttles. Using max throttles allows the earliest opportunity to continue to the prime TAL site and not have to risk possible control problems caused by a large yaw maneuver required to head to the ACLS. Reference Flight Rule {A2-52C}, ASCENT MODE PRIORITIES FOR PERFORMANCE CASES, for more details on using max throttles for this case. If this boundary has not been reached yet and the NEGATIVE ACLS boundary has been crossed, this call will be made on 0 sigma MPS to close the gap. These cases, by definition, reach the range-velocity (R-V) target line; however, they do so at a lower velocity than the design point. For this reason, entry dispersions are not explicitly protected, although for any given mission, the protection level for these constraints (first roll reversal velocity, constant drag phase length, and equilibrium glide boundary margin) may vary from less than 1-sigma to more than 3-sigma (reference 5/18/94 Abort Panel splinter meeting).
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a. DROOP (PRIME TAL OR ACLS - 109):
THE DROOP BOUNDARY REPRESENTS THE EARLIEST TIME AFTER
WHICH A TWO-SSME-OUT TRAJECTORY WILL NOT FALL BELOW
265,000 FEET AND TAL GUIDANCE WILL CONVERGE TO THE
SELECTED/REDESIGNATED SITE’S MECO TARGETS PRIOR TO
THE DESIRED MECO TIME. THIS BOUNDARY ASSUMES TWO
SSME’S OUT, MAX THROTTLE, AND 15-SECOND ABORT
DECISION DELAY. THE WEATHER AT THE SITE WILL NOT BE
A CONSIDERATION WHEN ASSESSING THIS BOUNDARY.
This boundary is the earliest time that TAL guidance can be used on a two-engine-out trajectory. It ensures that the minimum droop altitude will not be violated. Analysis has shown that trajectories that droop below 265,000 feet could result in ET rupture due to aerodynamic heating. If, upon TAL droop declaration, guidance is unconverged, the crew’s procedures call for flying manually until guidance does converge. (The likelihood of unconverged guidance in this region was significantly reduced by incorporation of the OI-21 low-thrust-to-weight guidance CR.) This boundary does not ensure the capability to reach a runway. Therefore, the weather at the targeted site is not considered when evaluating this boundary.
Mark Kirkman