J79 Modeling

[Schwokol]

So far, I am extremely impressed with Heatblur's rendition of the Phantom. However, (I know this might sound nitpick-y) the realism of engine simulations is always important to me and is vital in providing an immersive simulation. There are a couple of quirks I noticed about the J79 modeling that I hope Heatblur can clarify.

During startup, EGT immediately climbs to and stays at 450C, regardless of RPM and fuel flow. I am almost certain this behavior is incorrect. EGT should rise as FF and RPM initially increase, peak at a certain value (depending mostly on ambient conditions), and fall once RPM is high enough to provide sufficient cooling air. 

Second, the RPM throttle response time is unusually fast for a gas turbine engine. I have listened closely to a few real-life F4 demo videos, and I do recognize that the engines spool quite quickly. However, the J79s in DCS can spool from 65% to 100% in about half a second. 

[lxsapper]

I think it is a bug, the checklist and the training mission say to watch for EGT increase, but when the engine comes alive we actually see a decrease in ETG.

[Schwokol]

23 minutes ago, lxsapper said:

I think it is a bug, the checklist and the training mission say to watch for EGT increase, but when the engine comes alive we actually see a decrease in ETG.

You would expect to see an EGT decrease once the engine reaches idle. The problem is that EGT remains static at 450C throughout the whole start sequence. We should see the EGT rapidly rise once fuel is introduced, peak, and then gradually decrease as RPM increases. 

[lxsapper]

22 minutes ago, Schwokol said:

You would expect to see an EGT decrease once the engine reaches idle. The problem is that EGT remains static at 450C throughout the whole start sequence. We should see the EGT rapidly rise once fuel is introduced, peak, and then gradually decrease as RPM increases. 

Correct, what I was saying is that it imediatly rises when advancing the throttle to 50% and then back to idle, and it never rises past that as RPMs rise up. We only see the decrease at engine stabelizing. 

Edited May 24, 2024 by lxsapper

[Schwokol]

2 hours ago, lxsapper said:

Correct, what I was saying is that it imediatly rises when advancing the throttle to 50% and then back to idle, and it never rises past that as RPMs rise up. We only see the decrease at engine stabelizing. 

 

Ah gotcha