FC 3: F-15 intakes work wrong

[mytai01]

This is one of those things that I can not understand how it isn't fixed after all this time and with all the videos that demonstrate the way they really work. The F-15's jet intakes! If DCS gets this right I'll be impressed with their attention to detail. This is what an F-15's intakes do during startup:

 

This one has better sound and also demostrates the loud sound associated with the "turkery feather" operation:

 

This one demostrates the inflight operation of the intakes:

 

You DCS programmers need to pay attention!

[NoJoe]

Perhaps if a DCS: F-15 comes out they'll model this. For now, this kind of thing is probably a bit beyond the intended detail level of the Flaming Cliffs aircraft.

 

--NoJoe

[GC1993]

Totes agree with them fixing the intakes, and would be awesome too if they added the APU noise to the startup!

Extra extra bonus would be if they included that whistle sound of the nozzle actuators when thrust is increased for the advanced flight model when they make it, but this is serious wishful thinking now and I'm getting carried away :thumbup:

[strikeeagle]

US F-15's do not have turkey feathers and no F-15 has an APU. It has a JFS and a CGB. The JFS only provides power for the ready light, map light, ground comm, and AMAD fire protection. No hydraulics and total aircraft electrical power is provided by the secondary power system.

 

The nozzle actuators do not whistle. On -220/-229 powered jets, you're hearing the air from the exhaust of a component called the convergent exhaust nozzle controller (CENC). 13th stage engine bleed air and fuel pressure from the main fuel control (MFC) operate the CENC where two "flex shafts" connect to one of five nozzle actuators, which in turn are connected to the other four by a secondary flex shaft ring. The five actuators are connected to a CENC ring that is connected to the nozzle via push/pull rods connected to bell cranks on the nozzle.

 

On the ground and the throttle is at idle, the nozzle is open. Push the power up it starts to close. Therefore, at mil power the nozzle is closed. In flight, the nozzle is ALWAYS closed until burner is selected. It doesn't open again until the MLG touch the ground.

 

Class dismissed.

[strikeeagle]

Forgot about the ramps:

 

The F-15 has five ramps. The first ramp (the big one everyone is talking about), the second ramp, third ramp (which is hinged to the second), diffuser ramp, and bypass door (on top).

 

At about .85 mach, the first ramp should be locked in the full up position, bypass door opened, third, and diffuser down.

 

In flight the ramp is controlled by two computers called air data processors (ADP). On the ground they are controlled by two devices called 50% switches...an I'm not getting into how they work.

[IvanK]

Prior to the latest 1.2.5 Patch the F15 Intake ramps appeared to be working correctly, in that Ramp 1 would respond to AOA changes in a logical manner, that is Increasing AOA resulted in Ramp 1 leading edge dropping ... i.e. the intake aligning with the Air flow, as can been seen in the referenced videos.

 

Now the exact opposite is occurring. As you increase AOA the Intake lip is now moving up.

[strikeeagle]

AoA isn't the only thing that the ADP uses to control ramp position. Pitot and static pressures are the major factors in ramp positioning. The ramps always move during flight and it does so independently from one another.