Douglas A-4M - AIRSPEED CORRECTIONS; ALTIMETER CORRECTIONS

NAVAIR 01- 4 0AVM-l
Se ction XI
External Dr ag
Weig ht -
Stor e It
em
Index
Pounds
Clean ai r cr aft 0
2 MK 12 2 0-mm guns 7 628
with 400 round s of
ammu nition
1 300-gallon Aer o- ID
15 183
f uel tank on ce nterlin e
2 inboa
rd wing pylons 12 140
2 outboar d wing pylons 14 128
2 mul tipl e ejecto r r acks 46 446
~ 2 5x300-pound MK 81
70 '
30 00
Snak
eye bombs
§
2 S30-pound MK 82
6"
1060
bombs
T otals 170 5585
As the mission is flown, tanks may be dropped and
stores will be ex pended , changing the external s tore
configur ation and thus the drag index.
"'Ref
er to NAVAIR 01-40AV-IT.
AI RSPEED CORRECTIONS
Sev eral co rre ctions to the ai rspeed indicator reading
must be added to a rr ive at the t rue airspeed of the
ai r craft. Two corrections peculiar to the indi ca tor
Hsel! are instru ment error and la g. T hese er ro r s,
which are us uaUy small, a re added aLgebraically to
the
indicator r ea ding to o btain the indi ca tor airspeed.
Cal ibra ted airs peed is equa I to the airspeed indica tor
re ading corrected for pos ition and instrument error.
P os iti on e rror, shown in figure (to be furnished at a
lat
er date ), is an error introdu ce d due to the loc a-
tion of the s tati c source at a point of nonambient
sta ti c pres s ur e.
Equivalent ai rspeed is equal to the airspeed indicator
r eading co rre cted for position error, inst r ument
error, and for the co mpressibility at a. par ticular
a ltitude.
True ai rspeed is rel a ted to equivalent airspeed by the
following: KTAS
::. K EAS x 1 /,fU
The quantity 1/ ,fli m ay be found in figures 11-3 and
11 -5.
Part 1
To co nvert cali br ate d airspeed to true airspeed and
true M ac h number, figure 11-2 is provided . Fi g-
ur e 11 - 2 has compressibility effects built into the
gra ph permittin g a direct step from calib r ated to
true a irspeed .
A
position e rr or is associated with the Mach number
indicated values and the true ?v l ach number v alues.
This re l ationship is shown in figure (to be furnished
a t a later date).
SAMPLE PROBLEM
Alt itude Cor re ct i on for
Posi
ti on Error
( For figure 11-6 )
( fr.l.t a to be furnished at a late r date. )
Mach Numb er Correcti on for Po sition
( For figure 11 -7)
(Data to be furnished at a la ter date.
Airspeed Conversion
(For figure 11 -2)
(A)
Ca libr ated ai rspeed .
(B)
Tr ue pressur e altitude
Ie)
True Mach numb er ..
(0 ) OAT . .. . ....
(E) True a irspeed.
ALT I METER CORRECTIONS
Err or
360 kn
25,000 (t
0.849
565 kn
The a
ltimeter is co nnected to the static source .
Pos
ition error . co rrections, sim il ar to those for air -
speed indications , mus t be applied to the alti meter
indications to obtain tru e pr ess ur e a ltitude. The
cor r ections a re given in figure (to be furnished at a
later da te ). Instrument er r or and a lt ime ter lag are
also prevalen t in the altimeter system . The lag
error (appr oxima t ely 200 fee t) could be signifi can t
in a lo w -altitude dive pullout.
SAMPLE PROBLEM
Airspeed Correction for Pos ition Erro r
(F or figure 11 -6)
(Data to be furnished at a later d.-lt e.
11 -7
§
B
,.,
I