Knock-limited blending characteristics of blends of triptane and 28-R aviation fuel Page: 4 of 25
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the reference ourve- ar plus 6 ml vas plotted. The test results
on 28-R Aue oAntadaig B 2;1 percent Ldaines. t leadedL to 5.96 ml
per gallon are shabon in fiura 4. An engine failure (piston and
0ylnder soufting) prevented the tes of 28-2 fuel. This piston and
oylinder failure e attrbutebd to insufficient clearance, and a
10656D pison.~ Instied In a new cylinder for the subsequent
The estimated le4n ait rich perfamance embers of the first
series of blends tested are presented s table I. Leanmmixture as
well as rih*mirtbure knook-lSaited performance aoved with in-
creasing triptan ontent. The fuel oantainng ylidines gave lover
knok-lim.ted 17-5 er Pnance than anticipated.
After the -4 engine was., ovetauled, the seccnd series of tests
on the trptane blends was begun. These tests are presented in the
chronological.order of engine testing. Figure 5 shows the data oca-
piled on March 21 for the blends containing O, 20, 40, 60, and 80
percent leaded.. triptane and28-R aviation fuel tested at an inlet-
air temperature of 2500 7, a coolant, temperature of 2500 7, and a
spark advance of 300 B .T.C. A steady increase in the lean- and the
rich-'mixtare knock-limted performance acocmpnied an increase in
Heron and Beatty (reference i) live suggested that, with uper-
charged engines, the plot of reciprocal of knock-limited indicated
mean effective pressure against octane number is a straight line.
The graph of reciprocal of knock-limited indicated mean effective
pressure against percentage caposition has been found convenient
in the prediction of blend performance of paraffinic fuels (refer-
ence 2). Figure 6 abow such a cross plot of the data in figure 5
at four fuel-air ratios. - These data indicate that a reciprocal
relation is approziastel satisfied by the blends of triptane and
28-3R aviation fuel.
The knock-limited performance data of the triptane blends
tested"on Maroh 22 at an inlet-air temperature of "1500 7, a coolant
temperature of 200 F7 and a spark advance of 350 B.T.C. are pre-
sented in figure 7, and a cros plot of the knock-limited idicated.
measi effective pregmuwe (reciprocal scale) against the percentage
composition is presented in figure 8. The progressive gains in
knook-limited indicated mean effective pressure for each adAtion~l
20-proent Mincrese in triptane concentration At' & fuel-air ratio of
0.0625 vere 45, 46, 71', and 103 pounds er square nch, respectively
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Evvard, John C.; Imming, Harry S. & Genco, Russell S. Knock-limited blending characteristics of blends of triptane and 28-R aviation fuel, report, April 1944; (digital.library.unt.edu/ark:/67531/metadc62355/m1/4/: accessed May 20, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.