Why is kgf used as a thrust force unit?
Can someone explain why War Thunder uses kgf instead of kN for thrust values in the game? Additionally, using the F-15A as an example, the thrust in the game is around 8500 kgf. If you convert this to newtons, it comes out to 83.36 kN, but as far as I know, the actual engines produce around 100.53 kN. This seems to occur with most aircraft, not just the F-15.
I am by no means an expert so someone will correct me however my understanding is:
Weight often irl if you aren’t American, is measured in kilograms, by using Kilogram-force as a unit it makes it easier to visualise things such as thrust-to-weight ratio, technically I believe kgf is a more accurate unit too but you can just add decimal places onto kN and achieve the same effect.
Generally kN is an SI universal measurement unit, with lbf (pounds-force) used by America and kgf used by other countries (particularly European ones).
As for the F-15 and its installed thrust being different to the engines net thrust, there is a factor known as channel loss, this is thrust loss caused by the installation of an engine into an aircraft as airflow is now restricted and in some cases more turbulent than when the engine is sat on a bench to test it’s output, this reduces its efficiency and power output.
There are few sources to describe the channel loss of most aircraft so Gaijin tends to adjust thrust and channel loss depending on whether an aircraft matches the performance charts available.
IRL channel loss can also vary with airspeed for example the intakes on the Mirage does not have fantastic channel loss at slower speeds IIRC.
Okay, so they focus on the performance of the whole aircraft instead of just the engine thrust? Is there any official answer to this, or is this the best speculation we have rn?
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In wt its all pure engine performance, they dont care if the intake on one plane is different then on a other, same engine same values shown in wt.
But i am currently not sure on what air density they show the values, i guess they simply show the maximum, no matter if thats only archivanle if u stay on the ground or fly 10km high.
Not like the stat card, the stat card alwqys show the plane performance on a specified hight.
kgf is typically used over kN because it’s a far better measurement to equate to mass, Divide by 100 and you have kN anyway.
I know, but the Thrust values are not the same as stated for the Aircafts Irl, even if you convert them.
Because engines in a plane have channel losses, compared to the ideal thrust performance from an engine on a static testing frame.
Because a myriad of things affect thrust? Thrust values IRL don’t follow the same conventions, while in WT it is simply equated to the standing thrust of the engine. 10000kgf can quickly turn to 16000/18000kgf at mach 1, and so on. There’s a power curve to be aware of, and for the most part it follows that well for the aircraft that have such information available.
Mainly each component should be accurate to real life. But not many aircraft statistics are known for bench thrust in addition to installed thrust (e.g with channel loss factored in).
Things like channel loss are almost never revealed to the public as they’re such niche metrics it isn’t as easy to understand as ‘top speed’ or ‘g limit’, the only time we know about such things is when they’re stand-out. For example a selling point of the Eurofighter’s intakes is that they deliver sub-3% channel loss IRL, compared to the F-15’s in-game of 20%.