system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why does the Lockheed C-130 Hercules still use propellers instead of jet engines?
gpt
There's a number of factors that lead to the decision to use a turboprop engine over a turbofan engine (your typical jet engine).

-Shorter take-offs. Turboprops perform better at short take-off and landings, which increases the versatility of the vehicle. Turboprops can handle lower air speeds better, thus the plane doesn't have as great a risk of stalling when taking off at lower speeds. The Hercules is a military transport so landing in sub-optimal airstrips is a very likely possibility.

-Fuel Efficiency. At sub-sonic speeds, turboprops have a higher fuel efficiency compared to turbofans. A comparison between similarly sized passenger aircrafts found that the turboprop burned about 2/3 the fueld per passenger compared to the turbofan. The Hercules is required to fly long distances so fuel-efficiency is key.

-Operating conditions. Turbofans offer two major features over turboprops - supersonic speeds, and a high operating ceiling. Turbofans (jet engines) can potentially fly faster and higher than a turboprop plane can. These two features, however, are not necessary for the Hercules. It cannot fly at super-sonic speeds with heavy payloads, and it can already achieve a 33,000ft operating ceiling.