GHB,
If you Google the heating value of kerosene, heptane and methanol you will find the kero is around 18500 BTU/LB, heptane is 19160 BTU/LB and methanol is 9880. Either is 13600 BTU/LB, not that bad and much better than methanol (but it is very expensive). Our engines don't like detonation (no piston engine likes it). What they like is for fuel to ignite and burn smoothly (but quickly)from one point through the charge. Detonation is all the charge going off at once. Smoothing the burn allows the pressure to build smoothly. Looking at methanol it burns very slow but doesn't detonate. This is why you have lots of spark advance when engines run methanol (like 35 deg) vs. 15 deg for gasoline (and why glow plug works so well with methanol). With the fixed compression engine like the Drone you need mostly ether for it to start and run well, but you need to smooth the fuel burn and that's were the mineral oil comes in. Kero also does the same thing in fuel for VC style diesels. This calming of the ether allows for the power to be released as the piston hits top dead center and starts the downward power stroke. As far as the Drone blowing up using standard diesel mix, this is no true. Many people have run them on DDD standard fuel, Dr. Diesels old English mix without damage, it just is much easier to start and get a setting with the Drone mix.
The Drone is a long stroke low rpm design to run around 6700 - 6800 rpm (ground). It turns an 11x10 or 12x8 prop for OTS stunt. In 1948 - 1950 the Drone won many stunt contests. People that had trouble running them didn't read the operating manual. They would try to run them like a short stroke layout. With the Drone as the engine starts you need to open the needle to smooth out the run. The ether has a very wide operating range (similar to methanol) as you richen it you do two things, First it controls the temperature and second it trims the compression. There was a VC head that works well and I have two of them that I have run my Drone on. It is a tuff, strongly build engine.
Getting back to the simple diesel of starter fluid with mineral oil, looking at the heat values we would have plenty of BTU's in this fuel. If mixed with mineral oil rather than castor should run smooth, at least for sport fuel. We know the John Deer SF works, but it is expensive. So it seems someone in diesel land should have tried some different brands of starting fluid and this mix should be lower cost.
Best, DennisT