The orbiter/SCA separation operational limits for the current target conditions of ALT free flights 1 through 5 are analyzed. The separation operational limits are used to verify that no separation design constraints are violated. The operational limits represent the acceptable dispersions in attainment of separation target conditions which assure safe separation. Safe separation is based on satisfying all specified separation design criteria except orbiter altitude at ALT interface airspeed. Separation operational limits are defined for each of the five orbiter tailcones on ALT free flight missions based upon preflight aerodynamics. The effect of carrier pilot steering compensation due to off-nominal flight conditions is determined to be within the separation operational limits

Seale, R. H.

English

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Produced by the NASA Center for Aerospace Information (CASI) 
https://ntrs.nasa.gov/search.jsp?R=19770014228 2020-03-22T11:14:28+00:00Z
ISPACE SHUTTLE ENGINEERING AND OPERATIONS SUPPORT
_	 ^	 N
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w	 vUi	 DESIGN NOTE NO. 1.4-7-50
	" .A	 SEPARATION OPERATIONAL LIMITS
	
w ^.0	 FOR ALT FREE FLIGHTS 1 THROUGH 5
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	min L-4 _4	 MISSION PLANNING, MISSION ANALYSIS, AND SOFTWARE FORMULATION
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31 MARCH 1977
	
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to 0.4 vN	 cr	 tiN A	 This Design Note is submitted to NASA under Task Ord
N ^'	 D0608, Task Assignment A, Contract NAS 9-14960 	
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PREPARED BY:
	 APPROVED BY: C,
R. H. Seale
	 C. L. Colwell
ALT Separation Task
	 ALT Separation Task Manager
488-5660, Ext. 281
	 488-5660, Ext. 281
APPROVED BY :
	 ^ , - ,
	
APPROVED BY:
--
 ^4 /^^fl
T. N. Wenglins:i
	 W. E. Ilay s, Project Manager
Powered Flight, Separation and
	 Mission Planning, Mission Analysis
Consumables Analysis
	 and Software Formulation
Technical Manager
	 488-5660, Ext. 266
488-5660, Ext. 228
TABLE OF CONTENTS
o	 ,
SECTION PAGE
1.0 SUMMARY 1
2.0 INTRODUCTION 2
3.0 DISCUSSION 3
3.1
	
Separation Design Criteria, Constraints, 3
and Dispersions
3.2	 Analytical Approach 5
4.0 RESULTS 7
5.0 CONCLUSIONS AND RECOMMENDATIONS 8
6.0 REFERENCES 9
i
-- 1. __-_
LIST OF TABLES
TABLE
	
TITLE
	
PAGE
1
	
Target Separation Equilibrium Glide
	
10
Conditions
2
	
Root Sum Square Composite Dispersions
	
11
ii
FIGURE
1
2
3
4
5
LIST OF FIGURES
TITLE	 PAGE
MPAD Support Requirements for Orbiter/SCA	 12
Separation
ALT Nominal Separation Airspeed Limits For	 13
Free Flights 1-5
Method of Determination of Separation	 14
Operational Limits
ALT Free Flight Nos. 1, 2, 4, and 5 Separation
	 16
Operational Limits
ALT Free Flight No. 3 Separation Operational 	 17
Limits
iii
ALT
h
KEAS
LB
N
Zrel
N
Zorb
RI
SCA
V
a
4•
sorb
A6
6e 
orb
-a	 --
GLOSSARY OF SYMBOLS
Approach and Landing Test
Altitude (MSL)
Knots Equivalent Airspeed
Reference Body Length
Relative Normal Acceleration
Orbiter Normal Load Factor
Rockwell International
Shuttle Carrier Aircraft
Airspeed
Angle of Attack
Orbiter Pitch Acceleration At Separation
Incidence Angle
Orbiter Elevon Setting
iv
11.0 SUMMARY
This report documents the details of an analysis to determine the
orbiter/SCA separation operational limits for the current target
conditions of ALT free flights 1 through 5. The separation operational
limits are used to verify that no separation design constraints are 	 ....
violated. The operational limits represent the acceptable
dispersions in attainment of separation target conditions which
assure safe separation. Safe separation is based on satisfying all
specified separation design criteria except orbiter altitude at ALT
interface airspeed. Separation operational limits are defined for
each of the five orbiter tailcone on ALT free flight missions based
upon preflight (wind tunnel) aerodynamics. The effect of carrier
pilot steering compensation due to off-nominal flight conditions
(as determined in the Boeing Launch Simulation No. 3) is determined to
be within the separation operational limits. It is recommended that
the current target conditions be retained for free flights 1 through 5
until ALT captive-inert postflight data is available for reverifica-
tion.
2.0 INTRODUCTION
A design rationale which includes flight test verification of the
target separation conditions that satiny all ALT separation design
requirements was proposed in Reference 1. That proposal was instru-
mental in the formalization of the ALT separation support requirements
as specified in Reference 2. A pictorial representation of those
support requirements is reproduced in Figure 1. This design note
documents the results of a MDTSCO off line analysis which contributes
to the development of the criteria for modifying ALT separation con-
figuration/flight conditions as depicted at the bottom of Figure 1.
Reconfiguring the incidence angle between ALT flights requires
demating and remating of the orbiter/SCA. Likewise, reconfiguring
separation elevon position between captive inert flights requires
demating and remating of the orbiter/SCA. It is therefore an overall
objective of the design rationale to determine the incidence angle
and separation elevon position which have a high probability of being
retained for all of the orbiter tailcone on configuration ALT flights.
An additional objective entails selecting separation initial accelera-
tions which accommodate the maximum launch airspeed compatible with
vehicle constraints. Accordingly R I recommended in Reference 3 the
incidence and target separation initial conditions for ALT free flights
1 through 5 (orbiter tailcone on configuration).
In order to verify that no separation design constraints are violated,
separation operational limits are generated by MDTSCO for the R I
prescribed separation tartlet conditions.
r'
2
3.0 DISCUSSION
Safe separation is based upon satisfying all known ALT separation
design criteria except orbiter altitude at ALT interface airspeed.
The operational limits represent the acceptable dispersions in
attainment of separation target conditions which assure safe separa-
tion. Separation operational limits are expressed in terms of
separation SCA angle of attack versus separation airspeed.
The dispersions in separation conditions that are expected to occur
during the five second crew decision time have been determined to be
approximately ±0.1 degrees in SCA angle of attack and ±5 KEAS in
airspeed (see References 4 and F). The objective of this analysis is
to verify that this pilot steering capability is within the separation
operational limits for the R I recommended target separation conditions.
3.1 Separation Design Criteria, Constraints, and Dispersions
The separation incidence angle, airspeed, and orbiter elevon setting
were determined based upon retaining common incidence angles for flights
1 through 5, maximizing separation airspeed, maximizing ALT interface
altitude, and achieving nominal initial separation accelerations of
approximately 0.75 g relative normal acceleration and between 0 and 6 deg/
sec t orbiter pitch acceleration. The upper limit on nominal target
separation airspeed is defined by orbiter structural loads. This limit
is 5 KEAS less than 1.1 g on the V-n diagram for the orbiter 751 limit
load. Figure 2 presents a portion of the orbiter 75' structural limit
load V-n diagram for the free flight 1 through 5 separation configurations
(see Reference 6). For flights 1, 2, 4, and 5 (63.9' L B orbiter cg
3
i
The data base assumptions are as follows:
1) Orbiter and carrier freestream and proximity aerodynamics are
defined in Reference 7.
2) Carrier engine thrust is defined in Reference 8.
3) Orbiter control system is defined in Reference 9.
4) Carrier control system is defined in Reference 10.
5) Second launch attempt mass properties are defined in Reference 11.
3.2 Analytical Approach
The analytical approach used to generate the separation operational
limits for each of the twe target conditions is illustrated in the
flow chart of Figure 3.
The first step is to select a candidate separation constraint. Each
of the first five constraints listed above is analyzed independently
in order to determine the one which constitutes the most restrictive
separation operational limit. Worst case dispersions of constraint
parameters are generated by tt:e root sum square technique. The con-
straint dependent root sum square composite dispersions for aero-
dynamic coefficients and elevon setting are tabulated in Table 2.
The first two columns are the composite dispersions which maximize the
forward and aft strut -forces. The attach point recontact constraint is
represented by the negative of the same composite dispersions, which
minimize the strut fords. The cone angle constraint is represented
by the arctangent of the longitudinal relative acceleration divided by
the normal relative acceleration.
The mated vehicle is then trimmed in pitch for a sequence of combina-
tions of angle of attack, and airspeed near the target condition, and
5
the constraint parameter is calculated. At each airspeed, the
angle of attack limit is obtained by interpolating for the angle
of attack for which the constraint is equaled.
The separation operational limits are defined by the constraints which
result in the most restrictive angle of attack limit. The equilibrium
glide angle of attack at the target separation airspeed is determined
for one of the most restrictive constraint composite dispersions. The
envelope of pilot steering capability to achieve the target separation
airspeed and angle of attack in the presence of design winds under
analogous dispersed conditions (see References 4 & 5) is then overlayed.
The process is repeated for each of the most restrictive constraints.
The composite envelope of pilot steering capability is then comprised
of the superposition of each of the individual envelopes.
Acceptability of target separation conditions is verified by the non
intersection of the composite envelope of pilot steering capability and
the separation operational limits.
The operational limits are initially defined with the (dated Trim
Program (Reference 11). They are then verified by simulation of post
separation dynamic responses using the Space Vehicle Dynamic Simulation
(Reference 12).
6
4.0 RESULTS
Figures 4 and 5 present the separation operational limits expressed
in terms of carrier angle of attack and airspeed for ALT free flights
no. 1, 2, 4, and 5 and flight no. 3 respectively. The ultimate limits
represent the angle of attack/airspeed boundary with no dispersions.
The operational limits are the angle of attack/airspeed
boundary with the composite la aerodynamic and elevon dispersions.
These limits represent the amount of allowable pilot variation aLout
the equilibrium glide target without violating a separation constraint.
The upper limit on carrier angle of attack is defined by the orbiter
load factor or the aft attach recontact constraints. The lower limit
on carrier angle of attack is defined by the forward load cell vernier
limit of 50000 lbs. For neither configuration do the constraints of
orbiter angle of attack or separation cone angle define a more restrictive
limit for the airspeed range investigated.
The pilot accuracy in achieving and maintaining equilibrium glide at
the separation target condition is illustrated on each figure. The
pilot variability is compatible with the operational limits and no
separation constraints are violated.
i
7
5.9 CONCLUSIONS AND RECOMMENDATIONS
The conclusions derived from this analyses are as follows:
1) The separation operational limits generated for the target
conditions of ALT free flights 1 through 5 based on 1u wind tunnel
aerodynamic data dispersions verify that no separation constraints are violated.
2) The most restrictive constraints which define the operational
limits are the aft attach point recontact constraint and the 29
orbiter normal load factor constraint.
3) The pilot steering capability derived from ALT Separation
,iulation No. 3 is within the separation operational limits.
It is therefore recommended that the separation target conditions
tabulated in Table 1 be retained for free flights 1 through 5 until
ALT captive inert postflight data is available for reverification.
8
6.0 REFERENCES
1. MDTSCO T11 No. 1.4-7-272, "Flight Test Verification of ALT
Separation Initial Conditions," 27 July 1976.
2. NASA Memorandum EX32/7609-180, "ALT Separation Support Require-
ments," 23 September 1976.
3. RI IL No. IGNCV/76-1018, "ALT Launch Incidence Angle, Launch
Velocity and Orbiter Elevon Position Update," 21 December 1976.
4. TBC D180-18407-5, "ALT Launch Simulation No. 3 and Captive Flight
Test Simulation No. 1 - 30 Day Report," 24 November, 1976.
5. MDTSCO DN No. 1.4-7=46, "Preliminary Analysis of the Boeing ALT
Separation Simulation No. 3," 6 December 1976.
6. RI IL No. 1GNCV/76-991, "Comparison,of Several Possible ALT
Launch Conditions," 5 November 1976.
7. MDTSCO TM No. 1.4-7-403 , "Update of ALT Separation Aerodynamic
Data Base," 31 March 1977.
8. RI Report No. SD75-SH-0033C-1, "Orbiter/741 Carrier Separation
Aerodynamic Data Book," November 1976.
9. RI Report yo. SD73-SH-0180G. "Space Shuttle Separation System
Data Book," January 1977.
10. NASA F1emo EJ3-74-171, "Definition of 747 FCS and Orbiter FCS for
Carrier/Orbiter Simulation dt NASA," September 1974.
11. TBC Document No. D180-18401-13, "747 Space Shuttle Orbiter Carrier
Aircraft. Modification (CAM) Mass Properties Status Report,"
November 1976.
12. MDTSCO DN No. 1.4-7-19, "ALT 747/Orbiter Mated Trim Computer Program,"
17 November 1975.
13. JSC IN No. 76-FM-26, "Space Vehicle Dynamics Simulation (SVDS) Program
Description," 6 May 1976.
9
TABLE 1
TARGET SEPARATION EQUILIBRIUM GLIDE CONDITIONS
FLIGHT NO. 1,2,4,5 3
ORBITER CG (% Ls) 63.9 65.9
Worb (LBS) 150000 150000
Ae (DEG) 6.0 6.0
6eorb (DEG) 0.0 1.5
V(KEAS) 267 264
N Z	( _^ .74 .88
rel
"orb (DEG/SEC 2 ) 2.50 3.58
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13
•	 FIGURE 3
METHOD OF DETERMINATION OF SEPARATIOY OPERATIONAL LIMITS
START
B
SELECT A CONSTRAINT TO BE ANALYZED
DETERMINE COMPOSITE AERO AND ELEVON
TOLERANCES FOR SELECTED CONSTRAINT
V = 260 KEAS
_ o
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AYES	
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---^ YES
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I
	
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YES
MOST RESTRICTIVE x747 LIMIT AT
EACH V ARE OPERATIONAL LIMITS
DETERMINE EQUILIBRIUi GLIDE AT VTARGET
FOR TOLERANCES FOR MOST RESTRICTIVE CONSTRAINTS
OVERLAY PILOT STEERING CAPABILITY ON EQUILIBRIUM
GLIDE a FOR MOST RESTRICTIVE CONSTRAINTS.
CONSTRUCT COMPOSITE PILOT STEERING CAPABILITY
WHICH E;lCOi1PASSES ALL OVERLAYS
15
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M. 11


Space shuttle engineering and operations support. Separation operational limits for ALT free flights 1 through 5

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