Flight and Test-Stand Investigation of High-Performance Fuels in Double-Row Radial Air-Cooled Engines 1: Determination of Cooling Characteristics of Flight Engine Page: 6 of 22
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NACA MR No. n4L20
of 0.08 and a carburetor-air temperature of 00 F. The calculations
necessary for developing the correlation were based on 4 portion of
a Tg oVe parallel to the T curves obtained with the seme
model double-row radial air-cooled engine od noted an 8 test s tnd.
This portion of the asenesam T orn wa necessary for dstemlning
the constants in the cooling equation because flight conditions pre-
vented maintaining a constant hiel-air ratio of 0.08 and because of
the limitations in cabiUretir metering'.. The analysis presented in
this report is based on T .
The mean effective gas t4mperature T5. was arrived at in the
conventional manner (reference 2). Because of fuel vaporization in
the intake manifolds, the temperature of the charge Tm could not
be accurately measured by a thermocouple and was therefore taken as
the sum of the carburetor-inlet temperature To and the computed
temperature rise across the supercharger..The values of T6 were
then determined fral' the: following equations, which are completely
derived in reference 2.
T T=T + 0.8T -T +0.81To +19.5 1 0 headss)
T = T +0.8 T + 0.62 . + 19.5 (barre
b 80b a gb o4ZLT L
Curves used for deter inig ie elpoieents n and m are Pre-
sented in figures 4 and 5. The exponents t were determined from
the elopes of the curves in figure 4 in which, chae air .flow is
plotted a inst T . ,a at -a cbnetnt caliair preesire drop
Ap and 'a fuel-air rttia of 0.08. ..Thbe eppnents a were determined
:In a similar manner fr'c figure.5 in which a p is'the variable
Instead of ochrge-air flow.. 'Correlation curves were then obtained
by lott aint or heads and for barrels.
Constant conditions here: difficult to maintain in flight; there-
fora, corrections had to be made for variations of Me and a ap
during rune when either of these factors was supposedly held con-
ptant. A series of preliminaity graphs was made for both the con-
struction ourves andi the corelation lines until the error due to
the variations of cAp and. Me .wase reduced to a negligible amount.
The final correlation o re s ar0 shwn in fiSure 6.
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Blackman, Calvin C.; White, H. Jack & Pragliola, Philip C. Flight and Test-Stand Investigation of High-Performance Fuels in Double-Row Radial Air-Cooled Engines 1: Determination of Cooling Characteristics of Flight Engine, report, December 20, 1944; (https://digital.library.unt.edu/ark:/67531/metadc62522/m1/6/: accessed May 25, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.