solomarineris

Given the physical limits of a combustion engine, what improvements would you expect in the last 30 years?
Frankly not much, we have to absolutely chuck the idea now using this archaic power plant. We should invest tenfold or more into developing a reliable electric car. (would I be willing to pay more taxes? Yea I would)

The sticking point for electric cars is battery technology. Even though battery technology is reportedly improving by up to 30% a year, it still takes a lot of batteries to store the same amount of energy as a gallon of gasoline that weighs only 6 pounds. Practical urban electric cars will be hitting the market soon but they won't serve the needs of a lot of people nearly as well as gasoline powered cars and trucks. They're also going to be quite expensive because of all those batteries.

In the meantime, gasoline engine technology for automobile use has advanced tremendously in the past 30 years or so, in part due to the advances in electronics. I read once (and can't find a source to back up the statement) that a car produced in the 1960s and 1970s produced as much as 400 times the pollution as a modern car. Most of them also produced less power and got worse gas mileage. Simultaneously improving power and economy while reducing pollution is a significant achievement in engine technology due in part to electronic ignition, electronic fuel injection, better materials, tighter tolerances, and other technological advances. Adjusted for inflation, these modern engines aren't that much more expensive than the old engines, either. Not too shabby.

Grashtel:

How about turning this around? If say a Global Hawk had landed somewhere in 1947 what could have been reverse engineered from it? As a Global Hawk is presumably much less advanced than an alien space ship, built by humans, and for this scenario it would have landed safely rather than crashing reverse engineering it would be far easier than from a crashed alien vehicle.

An interesting question. The basic aerodynamics of the Global Hawk wouldn't surprise anyone in 1947. They might be able to learn quite a bit about the alloys used in the airframe and especially in the jet engine. Jet engine technology was still in its infancy in 1947 with relatively short operational life and horrendous fuel consumption.

I suspect they'd have a much harder time understanding the avionics. The integrated circuits used in modern avionics are many orders of magnitude more complicated than any electronics made back then and you can't see what's going on inside of a chip. The satellite communications system might baffle them some 10 years before Sputnik. Without GPS signals, they'd likely have a hard time understanding how the plane navigated.

Now if one of the stealthy UCAVs like the X-47B were somehow transported back in time to 1947, that would likely baffle them. Its built of materials that didn't exist back then, is aerodynamically unstable, and has a lot of features that would just be outside of their experience.