Flying Hunters is one of the Technologies in Frostpunk. It unlocks the Hunters' Hangar, an upgrade to the Hunters' Hut. It provides 30 Raw Food per night by employing 15 Workers. This is 50% more Raw Food per building compared to the Hunters' Hut.
The prerequisite technology Hunters' Gear increases the output of Hunters' Huts to 20 (it does not affect Hangars), so this upgrade will increase the raw food per building by +50%, not +100% as a raw data comparison would suggest. The Hangar is substantially more expensive than the Hut, with the upgrade itself costing 20 wood and 40 steel per building. As such, if steel is tight, you could also research Hunting Tactics first, to improve the Raw Food per Worker ratio without spending a lot of steel. After researching it, upgrading to Hunters' Hangars is still a 50% upgrade to that ratio, since Hunting Tactics also applies to the Hunters' Hangar. See the Hunting Efficiency table for more information on the possible hunting setups.
Alternatively, you could follow the Hothouse path instead, if you can afford the Steam Cores and heating to keep them functional. When Hazards are enabled, it is wise to have both available, so the "Animal Migration" or "Rotting Roots" hazards are not as crippling.
This table shows the efficiency of various possible hunting setups. The factor can be multiplied by your Worker count to see how much Raw Food they would produce, or you can divide your necessary Raw Food production by this factor to see how many Workers you will need. The worker count necessary to supply the Endless mode starting population of 80 is also shown, as reference.