text stringlengths 0 16.9k | page_start int64 0 825 | page_end int64 0 825 | source_file stringclasses 99
values |
|---|---|---|---|
control speeds” set by these factors rather than
simple stall speeds based on C&,.
When a wing of a given planform has various
high lift devices added, the lift distribution and
stall pattern can be greatly affected. Deflec-
tion of trailing edge flaps increases the local
lift coe5cients in the flapped areas and ... | 104 | 104 | 00-80T-80.pdf |
NAVWEPS 00-801-80
BASIC AERODYNAMICS
1.4
1.2
iL
i 0.4
0.2
0
0 .05 ;!O .!5
DRAG COEFFICIENT, CD
I.4
I.2
j 1.0
^
5
t 0.6
ii
kl $ 0.6
t
i 0.4
0.2
0
DRAG COEFFICIENT, CD
Figure 1.34. Airplane Parasite and Induced Drag | 105 | 105 | 00-80T-80.pdf |
NAVWEPS 00-8OT-80
BASIC AERODYNAMICS
ure is not too accurate because of the sharper
variation of parasite drag at high angles of
attack. In a sense, the airplane efficiency fac-
tor would change from the constant value and
decrease. The deviation of the actual airplane
drag from the approximating curve is quite ... | 106 | 106 | 00-80T-80.pdf |
B I Y | 107 | 107 | 00-80T-80.pdf |
impression of the “barn door” size. Hence,
parasite drag can be appreciated as the result
of the dynamic pressure, 4, acting on the
equivalent parasite area, j. The “equivalent”
parasite area is defmed by this relationship as
a hypothetical surface with a C,=l.O which
produces the same parasite drag as the air-
... | 108 | 108 | 00-80T-80.pdf |
NAVWEPS 00-801-80
BASIC AERODYNAMICS
as great a speed or one-fourth as much parasite
drag at half the original speed. This fact may
be appreciated by the relationship of dynamic
pressure with speed-twice as much V, four
times as much 4, and four times as much D,.
This expressed variation of parasite drag with
s... | 109 | 109 | 00-80T-80.pdf |
NAVWEPS OO-ROT-80
BASIC AERODYNAMICS
VELOCITY KNOTS
Figure 9.35. Typical Airplane Drag Curves
93 | 110 | 110 | 00-80T-80.pdf |
NAVWEPS OO-BOT-80
BASIC AE,RODYNAMlCS
(C) The point of minimum total drag occurs
at a speed of 163 knots. Since this speed in-
curs the least total drag for lift-equal-weight
flight, the airplane is operating at (L/D)ma,.
Because of the particular manner in which
parasite and induced drags vary with speed
(para... | 111 | 111 | 00-80T-80.pdf |
NAVWEPS 00-8OT-80
AIRPLANE PERFORMANCE
The performance of an aircraft is. the most operating limitations and insight to obtain
important feature which defines its suitability the design performance of his aircraft. The
for specific missions. The principal items of performance section of the flight handbook
airplan... | 112 | 112 | 00-80T-80.pdf |
NAVWEPS 00-ROT-80
AIRPLANE PER,FORMANCE
REQUIRED THRUST AND POWER
DEFINITIONS
All of the principal items of flight perform-
ance involve steady state flight conditions and
equilibrium of the airplane. For the airplane
to remain in steady level flight, equilibrium
must be obtained by a lift equal to the air-
pl... | 113 | 113 | 00-80T-80.pdf |
Thus, induced power required will vary with
lift, aspect ratio, altitude, etc., in the same
manner as the induced drag. The only differ-
ence will be the variation with speed. If all
other factors remain constant, the induced
power required varies inversely with velocity
while induced’drag varies inversely with t... | 114 | 114 | 00-80T-80.pdf |
NAVWEPS OO-ROT-80
AIRPLANE PERFORMANCE
Figure 2.1. Airplane Thrust and Power Required
96 | 115 | 115 | 00-80T-80.pdf |
NAVWEPS OO-.ROT-80
AtRPlANE PERFORMANCE
Induced drag predominates at speeds below
the point of minimum total drag. When the
airplane is operated at the condition of mini-
mum power required, the total drag is 75
percent induced drag and 25 percent parasite
drag. Thus, the induced drag is three times as
great as... | 116 | 116 | 00-80T-80.pdf |
NAVWEPS OO-ROT-80
AIRPLANE PERFORMANCE
Figure 2.2. Effect of Weight on Thrust and Power Required | 117 | 117 | 00-80T-80.pdf |
in drag and there is a two-fold effect. A 50-
percent increase in weight produces an increase
of 83.8 percent in the power required to main-
tain a specific CL. This is the result of a 50-
percent increase in thrust required coupled with
a 22.5-percent increase in speed. The effect of a
weight change on thrust re... | 118 | 118 | 00-80T-80.pdf |
NAVWEPS 00-8OT-80
AIRPLANE PERFORMANCE
VELOCITY-KNOTS
VELOCITY-KNOTS
Figure 2.3. Effect of Equivalent Parasite Area, f, on Thrust and Power Required | 119 | 119 | 00-80T-80.pdf |
NAVWEPS Oo-8oT-80
AIRPLANE PERFORMANCE
THRUST
REQUIRED
(LB9
VELOCITY-KNOTS (TAS)
POWER
REK?
:D
VELOCITY-KNOTS (TAS)
Figure 2.4. Ekf of Altitude on Thrust and Power Required
103 | 120 | 120 | 00-80T-80.pdf |
NAVWEPS 00-8OT-80
AIRPLANE PERFORMANCE
cause the power required curve to flatten out
and move to higher velocities and powers
required.
The curves of thrust and power required and
their variation with weight, altitude, and con-
figuration are the basis of all phases of airplane
performance. These curves define ... | 121 | 121 | 00-80T-80.pdf |
NAVWEPS Oo-ROT-80
AIRPLANE PERFORMANCE
F=mo
F=$(mV)
T, = Q (V,-V,)
Pa= T,, V,
Pw=Q/,(v2-v,)2
2VI 7)p=-
v2 +v,
1.0
.9
.6
.7
.6
7p .5
.4
.3
.2
.I
0
0 .I .2 .3 .4 .5 .6 .? .6 .9 1.0
%f2
Figure 2.5. Principles of Propulsion
105 | 122 | 122 | 00-80T-80.pdf |
NAWEPS 0040140
AlRPLANE PERFORMANCE
Of course, the development of thrus,t with
some finite mass flow will require some finite
velocity change and there will be the inevita-
ble waste of power in the airstream. In order
to achieve high efficiency of propulsion, the
thrust should be developed with a minimum
of wa... | 123 | 123 | 00-80T-80.pdf |
known for converting fuel energy into propul-
sive energy. However, the intermittent action
of the reciprocating engine places practical
limits to the airflow that can be processed and
restricts the development of power. The con-
tinuous, steady flow feature of the gas turbine
allows such a powerplant to process ... | 124 | 124 | 00-80T-80.pdf |
NAVWEPS 00-807-80
AIRPLANE PERFORMANCE
INLET OR
DIFFUSER COMPRESSOR
COMBUSTION TAILPIPE
CHAMBER TURBINE NOZZLE
TURBOJET ENGINE CYCLE
2
iiT! TURBINE WORK .
E
2
E Y
it
COMPRESSOR
I 1 c
VOLUME. CU. FT.
Figure 2.6. Turbojet Engines
108 | 125 | 125 | 00-80T-80.pdf |
The partial expansion of the gases through
the turbine will provide the power to operate
the engine. As. the gases are discharged from
the turbine at point F, expansion will continue
through the tailpipe nozzle. until atmospheric
pressure is achieved in the exhaust. Thus,
continued expansion in the jet nozzle wil... | 126 | 126 | 00-80T-80.pdf |
NAVWEPS GOdOT-
AIRPLANE PERFORMANCE
DWGLE ENTRY
CENfRlFuGAL COMPRESSCR
f-~&ARGE
CENTRIFUGAL COMPRESSOR
9A
AXIAL FLOW COMPRESSOR
STA’VM BLADES7
INLET
SHAFT7
COMPRESSOR BLADING
USCHARGE
ROTATING
Rows
Figure 2.7. Compressor Types
110 | 127 | 127 | 00-80T-80.pdf |
at very high velocity and high kinetic energy.
A pressure rise is produced by subsequent ex-
pansion in the diffuser manifold by converting
the kinetic energy into static pressure energy.
The manifold then distributes the high pres-
sure discharge to the combustion chambers.
A double entry impeller allows a given... | 128 | 128 | 00-80T-80.pdf |
NAVWEPS 00-80T-80
AIRPLANE PERFORMANCE
PRIMARY
COMBUSTION
AIR7
TYPICAL COMBUSTION CHAMBER
SECONDARY Al R
OR COOLING FLOW
FUEL
SPRAY
NOZZLE
DISCHARGE
TO TURBINE
NOZZLES
COMBUsTlON
NUCLEUS
TURBINE SECTION
TUR’BINE NOZZLE VANES
r / 11 TmaiNt BLADES
TURBINE WHEEL SHAFT
TURBIhE BLADING
(STATIONARY)
(RO... | 129 | 129 | 00-80T-80.pdf |
maintain a nucleus of combustion in the com-
bustion chamber. In rhe normal combustion
process, the speed of flame propagation is quite
low and, if the local velocities are too high at
the forward end of the combustion chamber,
poor combustion will result and it is likely
rhar the flame will blow out. The seconda... | 130 | 130 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
is subjected to the bending and torsion of
the tangential impulse-reaction forces. The
blade must wirhstand these stresses which are
generally of a vibratory and cyclic nature
while at high temperatures. The elevated
temperatures at which the turbine must func-
tion produc... | 131 | 131 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
NOZZLE TYPES
CONVERGENT NOZZLE CONMRGPIT-DDMRGENT NOZZLE
--3- ~--
ENGINE OPERATING CONOITIONS
COMPRESSOR TURBlElE EXHAUST
NOZZLE
STATIC
PRESSURE
INLET
TEMPERATURE
CHANGE
INLET
VELOCITY
CHANGE
INLEl
Figure 2.9. Exhaust Nozzle Types and Engine Operating Conditions
... | 132 | 132 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
Generally, the overall fuel-air ratio of the
turbojet is quite low because of the limiting
turbine inlet temperature. The overall air-
fuel ratio is usually some value between 80 to
40 during ordinary operating conditions be-
cause of the large amount of secondary air or
c... | 133 | 133 | 00-80T-80.pdf |
be expected to vary as the square of the rota-
tive speed, N. However, since a variation in
rotative speed will alter airflow, fuel flow,
compressor and turbine efficiency, etc., the
thrust variation will be much greater than
just the second power of rotative speed. In-
stead of thrust being proportional to iV2, ... | 134 | 134 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
VARIATION OF THRUST AN0 POWER WITH VELOCITY
/
/STATIC THRUST
.
THRUST
AvA’&?eLE
POWER
AVAILABLE
1
THRUST
AVAILABLE
/
/ AV!$%EHp’ E
(CONSTANT ALTITUDE 8 RPM)
VELOCITY, KNOTS
100
90
80
i-cl
PERCENT 6o
mmlgTM 50
40 1
30
20
IO 1
VARIATION OF THRUST WITH RPM ... | 135 | 135 | 00-80T-80.pdf |
due to thc~ low combustion pressure and values
of c, from 2.0 to 4.0 are typical with aftet-
burner operation.
The turbojet engine usually has a strong
preference fot high RPM to produce low specif-
ic fuel consumption. Since the normal rated
thrust condition is a particular design point
for the engine, the mini... | 136 | 136 | 00-80T-80.pdf |
kAVWEPS OO-EOT-80
AIRPLANE PERFORMANCE
50,ooc
45,ooc
40,ooc
35,ooc
30.000
t
I
0” 2 25,000
5 a
20,000
SEA
LEVEL’
\ I
\\ !
\ \\
CONSUMPTION
,FIXED GEOMETRY
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.6 0.9 1.0
RATIO OF WANTITY) AT ALTITUDE
(QUANTIT’I) AT SEA LEVEL
Figure 2.7 1. Approximate Eftect of Altitude on... | 137 | 137 | 00-80T-80.pdf |
When the inlet ram and compressor pressure
ratio is fixed, the principal factor affecting the
specific fuel consumption is the inlet air temp-
erature. When the inlet air temperature is
lowered, a given heat addition can provide
relatively greater changes in pressure or vol-
ume. As a result, a given thrust outpu... | 138 | 138 | 00-80T-80.pdf |
NAVWEPS 00-807-80
AIRPLANE PERFORMANCE
ALL CURVES APPROPRIATE
FOR A PARTICULAR:
r
ALTITUDE
M&N NUMBER
BOUNDARY A&
DECELEFlATlON
BOUNDARY
MAFfGIN
w
E I (IDLE) N-RPM (MA%)
EXHAUST GAS
TEMPERATURE
RPM c
PRESSURE . _ . _ _ - - -
TEMPERATURE
rAILPIPE TOTAL
PRESSURE
Figure 2.12. Engine Governing and Instr... | 139 | 139 | 00-80T-80.pdf |
2 of figure 2.12. Curve 2 of this illustration
defines an upper limit of fuel flow which can
be tolerated within stall-surge and tempera-
ture limits. The governing apparatus of the
engine must limit the acceleration fuel flow
within this boundary.
To appreciate the governing requirements
during the acceleration... | 140 | 140 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
the centrifugal flow engine has relatively large
acceleration margins and good acceleration
characteristics result with the low rotational
inertia. The axial flow compressor must oper-
ate relatively close to the stall-surge limit to
obtain peak efficiency. Thus, the accele... | 141 | 141 | 00-80T-80.pdf |
the design service life with trouble-free opera-
tion. The following items describe the critical
areas encountered during the operational use
of the turbojet engine:
(1) The limiting exhaust gag tcmpcra;wcs pro-
vide the most important restrictions to the op-
eration of the turbojet engine. The turbine
component... | 142 | 142 | 00-80T-80.pdf |
NAVWEPS 00-BOT-80
AIRPLANE PERFORMANCE
COMPRESSOR STALL
COMPRESSOR
COMBUSTION EXHAUST
CHAMBER T”RB,NE NOZZLE
PRESSURE RISE
LIMITED BY
STATIC
PRESSURE
CHANGE
INLET
INCREASED
BLADE ANGLE
ROTATING
COMPRESSOR
,STEADY STATE
AXIAL FLOW VEL
/ VELOCITY COMPONENT
DUE TO ROTATION
EFFECT OF INLET TEMPERATURE
... | 143 | 143 | 00-80T-80.pdf |
attack for the rotating blade with a subsequent
increase in pressure rise. Of course, if the
change in angle of attack or pressure rise is
beyond some critical value, stall will occur.
While the stall phenomenon of a series of
rotating compressor blades differs from that
of a single airfoil section in a free airs... | 144 | 144 | 00-80T-80.pdf |
NAVWEPS OO-BOT-80
AIRPLANE PERFORMANCE
the lower temperatures can precipitate this
water out of solution in liquid or ice crystal
form.
High altitude flight produces relatively small
air mass flow through the engine and the rela-
tively low fuel flow rate. At these conditions
a malfunction of the fuel control a... | 145 | 145 | 00-80T-80.pdf |
certain type of operation. Of course, the
effect on service life of any particular load
spectrum must be anticipated.
One exception to the arbitrary time standard
for operation at high temperatures or sus-
tained high powers is the case of the after-
burner operation. When the cooling flow is
only that necessary... | 146 | 146 | 00-80T-80.pdf |
NAVWEPS 0040T-80
AIRPLANE PERFORMANCE
AFTERBURNER COMPONENTS
AFTt$lRNRNER
HOLDERS
PRE -COMPRESSOR
WATER INJECTION
WATER INJECTION
NOZZLES
CHAMBER NOZZLE
INJECTION
TURBINE-PROPELLER COMBINATION
REDUCTION
TURBINES
CHAMBER NOZZLE
Figure 2.14. Thrust Augmentation and the Gas Turbine-Propeller Combination
13... | 147 | 147 | 00-80T-80.pdf |
thrust. Because of the high fuel consumption
during afterburner operation and the adverse
effect on endurance, the use of the afterburner
should be limited to short periods of time.
In addition, there may be limited time for the
use of the afterburner due to critical heating
of supporting or adjacent structure in... | 148 | 148 | 00-80T-80.pdf |
3~PWbWtlOdWd 3NVldUlV
08-108-00 SdSMAVN | 149 | 149 | 00-80T-80.pdf |
the turboprop powerplant is rated by an
“equivalent shaft horsepower.”
T,y ESHP= BHP+325vp
where
ESHP=equivalent shaft horsepower
EHP= brake horsepower, or shaft horse-
power applied to the propeller
T,= jet thrust, lbs.
V=flight velocity, knots, TAS
‘1s = propeller efficiency
The gas turbine engine is capabl... | 150 | 150 | 00-80T-80.pdf |
151 | 151 | 00-80T-80.pdf | |
The specific fuel consumption of the turbo-
prop powerplant is defined as follows :
specific fuel consumption=
engine fuel flow
equivalent shaft horsepower
c=lbs. per hr.
ESHP
Typical values for specific fuel consumption, c,
range from 0.5 to 0.8 lbs. per hr. per ESHP.
The variation of specific fuel consumptio... | 152 | 152 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
INTAKE COMPRESSION COMBUSTION POWER EXHAUST
RECIPROCATING ENGINE
OPERATING CYCLE
E
\ \
‘. -. -\
B ------==.f=
EXHAUST
4
VOLUME
Figure 2.15. Reciprocating Engines
136 | 153 | 153 | 00-80T-80.pdf |
of friction and the mechanical output is less
than the available pressure energy. The power
output from the engine will be determined by
the magnitude and rate of the power impulses.
In order to determine the power output of the
reciprocating engine, a brake or load device is
attached to the output shaft and the ... | 154 | 154 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PRRFORMANCE
inlet pressure, throttle position, and super-
charger or impeller pressure ratio. Of course,
the throttle is the principal control of mani-
fold pressure and the throttling action controls
the pressure of the fuel-air mixture delivered
to the supercharger inlet. The pressur... | 155 | 155 | 00-80T-80.pdf |
PERCENT
POWEFI
CONSTANT
AIRFLOW
BEST
OVERLEAN WER-RICH
NAVWEPS 00-307-80
AIRPLANE PERFORMANCE
I FUEL-AIR RATIO
NORMAL COMBUSTION
SPARK
PLUG
DETONATION
FLAME PROPAGATION
BURNJNG IGNITION
FROM HOT SFfYT
NORMAL CCMBUSTION
COMPRESSION STROKE POWER STROKE
TOP CENTER ::::::::::::::::::::::::::::::::::::::::... | 156 | 156 | 00-80T-80.pdf |
NAVWEPS 00-8OT-RO
AIRPLANE PERFORMANCE
Obviously, spark ignition timing is an impor-
tant factor controlling the initial rise of pres-
sure in the combustion chamber. The ignition
of the fuel mixture must begin at the proper
time to allow flame front propagation and the
release of heat to build up peak pressure ... | 157 | 157 | 00-80T-80.pdf |
NAVWEPS 00-8OT-80
AIRPLANE PERFORMANCE
cruise power is the upper limit of power that
can be utilized for this operation. Higher air-
flows and higher power wirhout a change in
fuel-air ratio will intersect the knee of the
detonation envelope.
The primary factor relating the efficiency of
operation of the recipr... | 158 | 158 | 00-80T-80.pdf |
NAVWEPS OO-ROT-RO
AIRPLANE PERFORMANCE
EFFECT OF SUPERCHARGING ON ALTITUDE
PERFORMANCE
UNAVAILABLE
\
J
LOW SLOWER
\ LIMIT MAP
_c U&Q f-
HIGH SLOWER
LIMIT MAf
\ b CONSTANT
N,D
Figure 2.17. Fffect of Supercharging on Altitude Performonce
142 | 159 | 159 | 00-80T-80.pdf |
manifold pressure any greater than the induc-
tion system inlet pressure. As altitude is
increased with full throttle and a governed
RPM, the airflow through the engine is
reduced and BHP decreases. The first forms of
supercharging were of relatively low pressure
ratio and the added airflow and power could
be ha... | 160 | 160 | 00-80T-80.pdf |
NAVWEPS O&ROT-SO
AIRPLANE PERFORMANCE
specific fuel consumption is not adversely
affected as long as auto-lean or manual lean
power can be used at the cruise power setting.
One operating characteristic of the recipro-
cating engine is distinctly different from that
of the turbojet. Water vapor in the air will
c... | 161 | 161 | 00-80T-80.pdf |
and fatigue damage. By minimizing the
amount of total time spent at high power
setting, greater overhaul life of the powerplant
can be achieved. This should not imply that
the-takeoff rating of the engine should not be
used. Actually, the use of the full maximum
power at takeoff will accumulate less total
engine... | 162 | 162 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
-- r PROPELLER DISC
--
---
“1 *-
~3
_ =“,.?*a
--- -
-- --
PRESSURE CHANGE
P;;;lW;;E THROUGH DISC
1 ,
DISTRIBUTION OF
ROTATIONAL FLOW COMPONENT
mDAT TIP
VORTEX
ii- 2.18. Rhuiples of Ropellerr
146 | 163 | 163 | 00-80T-80.pdf |
it is more appropriate to define propeller effi-
ciency in the following manner:
‘)~= output propulsive power
mput shaft horsepower
where
vP= propeller efficiency
T= propeller thrust
V= flight velocity, knots
BHP= brake horsepower applied to the
propeller
Many di,fferent factors govern the efficiency of
a pr... | 164 | 164 | 00-80T-80.pdf |
NAVWEPS OO-ROT-RO
AIRPLANE PERFORMANCE
The governing of the engine-propeller combi-
nation will allow operation throughout a wide
range of power and speed while maintaining
efficient operation.
If the envelope of maximum propeller dfi-
ciency is available, the propulsive horsepower
available will appear as show... | 165 | 165 | 00-80T-80.pdf |
PRO~‘ELLER EFFICIENCY
ENVELOPE OF MAXIMUM EFFICIENCY
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
PROPELLER
EFFICIENCY
-lP
-I PROPELLER ADVANCE RATIO, J . . . . . . . . . . . . . . . . . . . . . ...... . . -.-................::::::::: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1: . . . . . . . .... | 166 | 166 | 00-80T-80.pdf |
MAWEPS 00-801-80
AIRPLANE PERFORMANCE
The various items of airplane performance
result from the combination of airplane and
powerplant characteristics. The aerodynamic
characteristics of the airplane generally define
the power and thrust requirements at various
conditions of flight while the powerplant
characte... | 167 | 167 | 00-80T-80.pdf |
NAVWEPS OO-ROT-80
AIRPLANE PERFORMANCE
THRUST
c
1 WEIGHT
THRUST
REQUIRED
I
-MAXIMUM LEVEL
FLIGHT SPEED
VELOCITY
POWER
REQUIRED
- MAXIMUM LEVEL
FLIGHT SPEED
VELOCITY
Figure 2.20. Level Right Pedormancc
151 | 168 | 168 | 00-80T-80.pdf |
NAVWEPS OO-SOT-80
AIRPLANE PERFORMANCE
The forces acting on the airplane during a
climb are shown by the illustration of figure
2.21. When the airplane is in steady flight
with moderate angle of climb, the vertical
component of lift is very nearly the same as the
actual lift. Such climbing flight would exist
wi... | 169 | 169 | 00-80T-80.pdf |
NAVWEPS OD-80T-80
AIRPLANE PERFORMANCE
w SIN ,-- COMPONENT OF WEIGHT
ALONG FLIGHT PATH
THRUST - - -- __---- AVAILABLE AVAILABLE
AND JET ACFT
THRUST
REOUIRED
LBS.
POWER
AVAILABLE
AND
POWER
REolYLRED
VELOCITY, KNOTS
l=‘a JET
Pr, POWER REOUIRED
POWER AVAILABLE
PROP ACFT
SPEED FOR MAX R.C., JET
SPEED FO... | 170 | 170 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
is at a minimum, (LID),. Thus, for maxi-
mum steady-state angle of climb, the turbojet
aircraft would be operated at the speed ,for
(L/D),. This poses somewhat of a problem
in determining the proper procedure for ob-
stacle clearance after takeoff. If the obstacle
is a con... | 171 | 171 | 00-80T-80.pdf |
172 | 172 | 00-80T-80.pdf | |
NAVWEPS 06801-80
AIRPLANE PERFORMANCE
near the speed for (L/D&-. There is no direct
relationship which establishes this situation
since the variation of propeller efficiency is the
principal factor accounting for the variation
of power available with velocity. In an ideal
sense, if the propeller efficiency were ... | 173 | 173 | 00-80T-80.pdf |
NAVWEPS C&801-80
AIRPLANE PERFORMANCE
TYPICAL PROPELLER AIRCRAFT ALTlTUOE PERFORMANCE
. RATE OF,CL!MB_, _-
.
tiAXlMUM LEVEL FLIGHT SPEED
HIGH BLOWER CRITICAL ALTITUDE
FEE0 FOR MA% R c
LOW BLOWER CRITICAL ALTITUDE
= y$y VELOCITY, KNOTS
-e-*--
TROPOPAUSE
t-
\ MAXIMUM LEVEL
\
\ FLIGHT SPEED
-RATE OF CLIMB ... | 174 | 174 | 00-80T-80.pdf |
NAVWEPS 00-8OT-80
AIRPLANE PERFORMANCE
with altitude above the tropopause. This is
due in great part to the more rapid decay of
engine thrust in the stratosphere.
During a power off descent the deficiency of
thrust and power define the angle of descent
and rate of descent. TWO particular points
are of interest ... | 175 | 175 | 00-80T-80.pdf |
NAVWEPS 00-501-50
AIRPLANE PERFORMANCE
FUEL
FLOW
I APPLICABLE FOR A
PARTICULAR: WEIGHT
MAXIMUM ALTITUDE
ENDURANCE CONFIGURATION
LINE FROM ORIGIN
TANGENT TO CURVE
VELOCITY, KNOTS
100%
MAXIMUM
-- 99% MAXIMUM RANGE
SPECIFIC
RANGE APPLICABLE FOR A PARTICLAR
-CONFIGURATION
-ALTITUDE
-WEIGHT
VELOCITY, KNOT... | 176 | 176 | 00-80T-80.pdf |
NAVWEPS oo-80~~80
AIRPLANE PERFORMANCE
obtained is approximately 75 percent of the
speed for maximum range.
A more exact analysis of range may be ob-
tained by a plot of specific range versus velocity
similar to the second graph of figure 2.23. Of
course, the source of these values of specific
range is derived ... | 177 | 177 | 00-80T-80.pdf |
NAVWEPS OS80140
AIRPLANE PERFORMANCE
flow is determined mainly by the shaft poluet
put into the propeller rather than thrust. Thus,
the powerplant fuel flow could be related di-
rectly to power required to maintain the air-
plane in steady, level flight. This fact allows
study of the range of the propeller power... | 178 | 178 | 00-80T-80.pdf |
NAVWEPS OO-ROT-RO
AIRPLANE PERFORMANCE
GENER,AL. RANGE CONDITIONS
PROPELLER AIRPLANE
POWER
REO’D
HP
APPLICABLE FOR
A PARTICULAR
MAXIMUM -WEIGHT
ENDURANCE -ALTITUDE
-CONFIGURATION
VELOCITY, KNOTS
POWER
REO’D
EFFECT OF GROSS WEIGHT
HlGHER WT.
CONSTANT
ALTITUDE
VELOCITY, KNOTS
HP HP
A t
EFFECT OF ALT... | 179 | 179 | 00-80T-80.pdf |
for WD)m.z, a change in altitude will produce
the following relationships:
where
condition (I) applies to some known condi-
tion of velocity and power required for
W’),,,,,z at some original, basic altitude
condirion (2) applies to some new values of
velocity and power required for (L/D),,
at some different alt... | 180 | 180 | 00-80T-80.pdf |
NAVWEPS OO-SOT-80
AIRPLANE PERFORMANCE
operational factors will define operating pro-
cedures.
RANGE, TURBOJET AIRPLANES. Many
different factors influence the range of the
turbojet airplane. In order to simplify the
analysis of the overall range problem, it is
convenient to separate airplane factors from
power... | 181 | 181 | 00-80T-80.pdf |
NAVWEPS 00-8OT-80
AIRPLANE PERFORMANCE
GENERAL RANGE CONDITIONS
TURBOJET
THRUST
REO’D
LBS
THRUST
REO’D
LBS
THRUST
REP’0
LBS
MAXIMUM
ENDURANCE
MAXIMUM
APPLICABLE FOR
A PARTICULAR
-WEIGHT
-ALTITUDE
-CONFIGURATION
VELOCITY, KNOTS
EFFECT OF GROSS WEIGHT
CONSTANT
ALTITUDE
t
EFFECT OF ALTITUDE
.%A ... | 182 | 182 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
have a fuel weight which is a large part of the
gross weight, cruise control procedures will be
necessary to account for the changes in opti-
mum airspeeds and power settings as fuel is
consumed.
The effect of altitude on the range of the
turbojet airplane is of great impo... | 183 | 183 | 00-80T-80.pdf |
From the previous analysis, it is apparent
that the cruise altitude of the turbojet should
be as high as possible within compressibility
or thrust limits. Generally, the optimum alti-
tude to begin cruise is the highest altitude at
which the maximum continuous thrust can
provide the optimum aerodynamic conditions... | 184 | 184 | 00-80T-80.pdf |
NAVWEPS oo-801-80
AIRPLANE PERFORMANCE
where
condition (1) applies to some known condi-
tion of weight, fuel flow, and specific
range at some original basic altitude
during cruise climb.
con&&r (2) applies to some new values of
weight, fuel flow, and specific range at
some different altitude along a partic-
u... | 185 | 185 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
TURBOJET CRUISE-CLIMB
t-
IF CL AND TAS ARE CONSTANT,
LIFT IS PROPORTIONAL TOE
IF co AND T/h ARE CONSTANT,
DRAG IS PROPORTIONAL TO a
(SPEEDS FOR MAXIMUM
FUEL GROUNO NAUTICAL ,MlLES
FLOW PER LB. OF FUEL)
LBS/HR I HEADWIND I /
I
IF RPM AND TAS ARE CONSTANT,
THRUST IS PR... | 186 | 186 | 00-80T-80.pdf |
NAVWEPS 00401-60
AIRPLANE PERFORMANCE
greatly with altitude, the turbojet can tolerate
less favorable (or more unfavorable) winds
with increased altitude.
In some cases, large values of wind may
cause a significant change in cruise velocity to
maintain maximum ground nautical miles per
lb. of fuel. As an exampl... | 187 | 187 | 00-80T-80.pdf |
NAV’iiEPS Oo-801-80
AIRPLANE PERFORMANCE
EFFECT OF ALTlTUOE ON MINIMUM
POWER REO’D
b
AT ALTITUDE
SEA.LEVEL /
/
MINIMUM /
/
/
CONSTANT
WEIGHT 8
CONFIGURATION
lm-
VELOCITY, KNOTS
EFFECT OF ALTITUDE ON MINIMUM
t
THRUST REO’D
SEA LEVEL AT ALTITUDE
T;;;g MINIMUM THRUST REO’D
LBS /’
A’
,’
CONSTANT
--... | 188 | 188 | 00-80T-80.pdf |
NAVWEPJ OO-ROT-80
AIRPLANE PERFORMANCE
to airplane factors. The turboprop power-
plant prefers operation at low inlet air tem-
peratures and relatively high power setting to
produce low specific fuel consumption. While
an increase in altitude will increase the mini-
mum power required for the airplane, the
powe... | 189 | 189 | 00-80T-80.pdf |
problem will be most .critical if the airplane is
at high altitude, high gross weight, and with
gaps and gear extended. Lower altitude,
jettisoning of weight items, and cleaning up
the airplane will reduce the power required for
flight. Of course, the propeller on the in-
operative engine must be feathered or the... | 190 | 190 | 00-80T-80.pdf |
191 | 191 | 00-80T-80.pdf | |
turboprop airplane but additional factors are
available to influence the specific endurance at
low altitude. In other words, low altitude
endurance can be improved by shutting down
some powerplants and operating the remaining
powerplants at higher, more efbcient power
setting. Many operational factors could decid... | 192 | 192 | 00-80T-80.pdf |
NAVWEPS oo-80mo
AIRPLANE PERFORMANCE
would be to provide the endurance thrust with
some engine(s) shut down and the remaining
engine(s) operating at a more efficient power
output. This technique would cause a mmi-
mum loss of endurance if at low altitude. The
feasibility of such a procedure is dependent
on many... | 193 | 193 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
CENTRIFUGAL FORCE
iRUST
I I TURNING FLIGHT&
\ \
I VELOCITY, KNOTS
LEVEL FLIGHT
VELOCITY, KNOTS
Figure 2.28. Effect of Turning Flight
177 | 194 | 194 | 00-80T-80.pdf |
NAVWEPS 00-8OT-80
AIRPLANE PERFORMANCE
important-if not more important-as the
increased stall speed in turning flight. It is
important also that any turn be well coordi-
nated to prevent the increased drag attendant
to a sideslip.
TURNING PERFORMANCE. The hori-
zontal component of lift will equal the centrif-
... | 195 | 195 | 00-80T-80.pdf |
196 | 196 | 00-80T-80.pdf | |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
define the maximum turning performance.
The acrodynomic limir describes the minimum
turn radius available to the airplane when
operated at C,,,,. When the airplane is at the
stall speed in level flight, all the lift is neces-
sary to sustain the aircraft in flight and none ... | 197 | 197 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
A
TURN
RADIUS
F:
A-- I t
VELOCITY, KNOTS (TAS)
EFFECT OF AERODYNAMIC AND
STRUCTURAL LIMIT ON TURNING
PERFORMANCE
ABSOLUTE MINIMUM
L
TURN
RADIUS
F:
CONSTANT ALTITUDE TURNING
PERFORMANCE
I
,-INCREASING
BANK ANGLE
THRUST OR
t
VELOCITY, KNOTS (TAS)
figure 2.30.... | 198 | 198 | 00-80T-80.pdf |
NAVWEPS OO-EOT-80
AIRPLANE PERFORMANCE
cause the airplane to descend. However, as
speed is reduced below the maximum level
flight speed, parasite drag reduces and allows
increased load factors and bank angles and
reduced radius of turn, i.e., decreased parasite
drag allows increased induced drag to accom-
modat... | 199 | 199 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE | 200 | 200 | 00-80T-80.pdf |
NAVWEPS 00-801-80
AIRPLANE PERFORMANCE
the distance varies directly as the square of the
velocity and inversely as the acceleration.
As an example of this relationship, assume
that during takeoff an airplane is, accelerated
uniformly from zero velocity to a takeoff
velocity of 150 knots (253.5 ft. per sec.) with... | 201 | 201 | 00-80T-80.pdf |
The acceleration of the airplane at any
instant during takeoff roll is a function of the
net accelerating force and the airplane mass.
From Newton’s second law of motion:
or
where
a=acceleration,~fr. per set
Fn- net accelerating force,
W=weight, lbs.
g? gravitational accelerat
=32.17 ft. per sec.*
M= mass, s... | 202 | 202 | 00-80T-80.pdf |
NAVWEPS O&601-80
AIRPLANE PERFORMANCE
FORCES ACTING ON THE AIRPLANE DURING
TAKEOFF ROLL
LlFT,L7
/’
,-THRUST (PROPELLER), T ,/
/
THRUST (JETI,T /
/’ ‘\
(T-D-F) / ‘1
NET
ACCELERATING /’
FORCE
(PROPELLER)- , I ’
(T;&F)
CONSTANT
a 1
ACCELERATING
INNING WHICH IS ESSENTIALLY POINT OFF
OF TAKEOFF PROPORTIO... | 203 | 203 | 00-80T-80.pdf |
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