Juno: New Origins | jet engine rebalance

(In Version 0.8.201.0)

Performance of a large high bypass turbofan is much weaker than the one in reality.
In game, a jet engine with 300% size, 7.0 bypass ratio and 30.00 compression ratio only produce 389kN static thrust on the ground. In reality, GE90 with a 3.3 meter fan, 9.0 bypass ratio and 42 compression ratio could produce 513kN static thrust.
Performance of a small turbojet is much better than the one in reality.
In game,a jet engine with afterburner, 98% size, 0 bypass ratio and 13.5 compression ratio could produce 178kN static thrust on the ground and reach TWR of 13.92 ! In reality, J79 afterburning turbo jet with 0.98m diameter, 0 bypass ratio and 13.5 compression ratio only produce 79.33kN static thrust on the ground, TWR is only 4.6.
jet engines on default aircraft "SimpleAirways" are quite different from their counterparts in reality and may mislead players or students.
In game, jet engines on "SimpleAirways" have 250% size, 0.45 bypass ratio and 9.5 compression ratio and produce 642 kN static thrust on the ground. In reality, CF6-80C2 on Boeing 747 has 2.69 meter fan, 5.31 bypass ratio and 31.8 compression ratio, producing 275.6kN thrust during takeoff.
So default aircraft "SimpleAirways" is using low bypass turbofans with smaller size but much higher thrust and much lower efficiency compare to CF6 on B747.

2,040 Frolonov

Not sure if SimpleAirways got removed from the stock craft due to the engine code issue mentioned in this post. Hope it will return and become more realistic in terms of flight performance when the jet engine code gets an update.

1.1 years ago

TSFC chart and constant volume combustion added to the MATLAB script on Apr 6,2023.
Constant volume combustion could approximate piston engine or rotating detonation engine, which offer much better fuel efficiency compared to constant pressure combustion in conventional jet engine. This might make jet engine more attractive in the game compared to electrical propulsion or rocket engine, especially in hypersonic flight.
@AndrewGarrison

No problem, that just mean I have more time to improve my code before you actually need it. Let me know when you're ready to work on this. It'll be pretty exciting to get more features like this in the game.
@AndrewGarrison

Dev AndrewGarrison

We appreciate the time and effort you put into such a detailed feature suggestion and you've shown great tenacity to come back to it so many years later! We don't have the resources available to take this on right now, but of course we always try to keep player suggestions in mind as we continue to develop this game. Thanks for playing!

1.2 years ago

https://steamcommunity.com/app/870200/discussions/0/3819655068774976906/
I put more details in the post including pictures to compare engines in the code and in the current game.
@AndrewGarrison

I posted a discussion and link to my code on steam.
See if you can make use of it if you're interested.
@AndrewGarrison
https://steamcommunity.com/app/870200/discussions/0/3819655068774976906/

It's weird that a turbofan in this game with 300% size, 30 compression ratio and 7 bypass ratio hardly push the aircraft to M0.8. But a turbofan in reality may reach M0.95 easily. @AndrewGarrison

4.5 years ago

The major problem is that thrust of high-bypass turbo fan in this game is too sensitive to speed. In the game, as Mach number increase from 0 to 0.8, maximum thrust would decrease from 100% to roughly 63%, no matter what altitude it is working on-this is making the engine too weak during climbing. In reality, as altitude increase, maximum thrust of turbo fan would become less sensitive to Mach number(for example, on 10km, maximum thrust of a turbofan is almost a constant from Mach 0 to 0.8, while on the ground, the thrust would drop from 100% to 63%).@AndrewGarrison

+1 4.5 years ago

jet engine rebalance

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