Just about every reference I have puts diesel at 10-25. I gave jeta the benefit of the doubt.
Very different fuels, diesel fuel and jet/kerosine.
Hydrocarbon properties tend to group with their densities and boiling points...
Gasolines boil from 100F to 400F, roughly (there are complicating factors, and avgas is slightly lighter, end boiling point in the high 300's) and weigh ~6#/gallon
Jet fuel and kerosene boil from about 300F to 500F, and weigh 13% more than gasoline
Diesel fuel or salable gasoil boils from 350F to 650F (in western countries), and weigh 13% more than jet...
I've never worried about octane number of diesel, as that's pretty much a non-starter and not a common misfueling circumstance. Let's say we accept your 25 octane. Straight run gasoline is about 70 octane (depends highly on the crude oil composition... Arabian and California crudes are higher, Pennsylvania crudes are lower**)
If we interpolate across the range, that would give jet octane of about 50, which is what my experience blending gasoline for 38 years suggests.
The NASA study you cite has the same data blindness that the FAA exhibited a few years later, when they began the unleaded avgas study that lasted 20 years... they assumed all avgas was the same, and it is not... the composition varies significantly depending on the refining details of where it comes from... and they assumed that avgas properties matched the spec pretty much exactly. But, they do not... blenders always build in some give-away on properties, particularly avgas octane, to avoid surprises further down the supply chain.
The NASA study cites their experimentation with avgas and jet fuels, and even delves into the feasibility of GC in the field (gas chromatography). But in the 86 pages I perused, they don't define the starting points... what were the composition(s) of the avgas samples they were using? What were the compositions of the jet/kero samples they were using? Without knowing the starting points, the conclusions down the road are just random noise. Sad.
**Crude origin and refinery configuration make a big, significant difference! Although Lindbergh departed for Paris from New York, he didn't use gasoline from New Jersey refineries, just across the waterway... he imported gasoline from California. It wasn't because we're so much nicer folks out here... it's because Lindbergh's testing revealed that California gasoline had some as yet undefined property (octane rating) that allowed him to run leaner without his engine overheating (due to detonation). That's because straight-run California gasoline (and straight run was pretty much all that was available back then, very little molecule re-arranging chemistry and equipment available) has inherently higher octane, maybe as much as 10 octane numbers higher due to its naphthene content. He observed this by leaning at night and noticing when burning California gasoline, his cylinders didn't glow quite as brightly orange.
The NASA data suggests about 1 octane number loss for each 1% jet dilution into gasoline. That does not match any blend tables that I've looked at... I didn't bring thousands of blend tables with me into retirement (thankfully), but that correlation isn't consistent with the post-mortems from the 1994 4,000 engine misfueling incident either.
Paul
