FAQ for F-15 AFM Development

[GGTharos]

CAS should trim for weight imbalance :)

 

The high altitude 'flipping' issue Blaze is describing is probably the rudder issue (pull enough AoA with a little roll, and the plane goes into an auto-roll).

 

Guys, could you help me. I may missed something. What exact problem do you have at 40k feet? Could you provide track and description what is wrong and how it must work correctly?

[lunaticfringe]

CAS should trim for weight imbalance :)

 

Not at 32 AoA.

[GGTharos]

The CAS will attempt to nullify motions that do not result from pilot input in all three channels. The problem described above has more to do with rudder issues that are currently being fixed, at least AFAIK.

 

Not at 32 AoA.

[mytai01]

The turkey feathers don't open all the way when the aircraft is in flight when at idle power. This is incorrect. Also, there is a very distinctive noise they make when they open up. See this link for that noise: http://www.youtube.com/watch?v=3slu0j9tDRE. The sound is about 3:10 into the video. Also, note how when they close the sound of the engines changes a little.

Edited June 10, 2014 by mytai01

[Exorcet]

Not at 32 AoA.

You have to trim any time your weight isn't equal right now, even at cruise.

 

Which reminds me, in the real plane do you fire all the missiles on one side before the other? That doesn't seem right to me. I'd think you would, for example exhaust the underwing pylons before you get to the conformal missiles. In FC3 this isn't the case and the weight imbalance grows a lot more than it would otherwise.

[blkspade]

As I have pointed out previously, for what ever reason the sim sorts missile from left to right, leaving you even heavier on the cannon side. There is a way to work around this if you configure your load-out a certain way. I'd imagine the RL Eagle's missile reject option would prevent this as well it probably sorting right to left instead.

 

You have to trim any time your weight isn't equal right now, even at cruise.

 

Which reminds me, in the real plane do you fire all the missiles on one side before the other? That doesn't seem right to me. I'd think you would, for example exhaust the underwing pylons before you get to the conformal missiles. In FC3 this isn't the case and the weight imbalance grows a lot more than it would otherwise.

[sobek]

The turkey feathers don't open all the way when the aircraft is in flight when at idle power. This is incorrect.

 

Got any sources on that?

[Rainmaker]

The turkey feathers don't open all the way when the aircraft is in flight when at idle power. This is incorrect. Also, there is a very distinctive noise they make when they open up. See this link for that noise: http://www.youtube.com/watch?v=3slu0j9tDRE. The sound is about 3:10 into the video. Also, note how when they close the sound of the engines changes a little.

 

 

No, it is correctly modeled actually. The augmentors are controlled by the gear handle. With weight off wheels, and the gear handle up, the augs are in a closed percentage just around a mil nozzle percentage( I believe the max allowable is 20% open at idle but I would have to check numbers again). Edit: Actually, TBH, it's not even WoW related as you can do the same thing on the ground with just the gear handle. As far as the actuators, they are bleed air driven, and the sound is nothing more than the actuators transitioning. And no, it's not something that you will hear inflight.

 

So where are we going with this?

Edited June 10, 2014 by Rainmaker

[sobek]

I guess his point is that you can hear them on the outside.

[Rainmaker]

I guess his point is that you can hear them on the outside.

 

True, just seemed like he was making some kind of bug report, so not really sure what the thought was behind trying to identify it.

[TAW_Blaze]

You have to trim any time your weight isn't equal right now, even at cruise.

 

Which reminds me, in the real plane do you fire all the missiles on one side before the other? That doesn't seem right to me. I'd think you would, for example exhaust the underwing pylons before you get to the conformal missiles. In FC3 this isn't the case and the weight imbalance grows a lot more than it would otherwise.

 

It doesn't matter anyway because trim is worthless currently. No point trying to trim it out it either results in the opposite of what you want or it just doesn't do enough. It needs to be more detailed, a trim function that behaves like a massive kick on the control surface is not very useful.

[GGTharos]

cofcorpse is aware of a number of issues and he is working on them. Now quit squabbling.

[TAW_Blaze]

Well, to be fair, many of us asked about this, I don't even remember how many times. No response was given, whatsoever. Thanks anyway, sorry for being a bit inconvenient.

[mytai01]

disassociate the wing root beacon lights from the landing/taxi lights and make them flash the way they are supposed to. There are enough videos out there to get this right, and it's simple.

[mytai01]

You need to hang around an F-15 unit more. The actuators are heard in flight especially during landing right after they complete there turn to downwind and on final every time the throttles are pulled back! See the YouTube video titled, "C-130's, F-16's and F-15's landing at Nellis AFB." One of the F-15's makes the sound I described IN-FLIGHT!

Edited June 12, 2014 by mytai01

[SDsc0rch]

@mytai....... wait a sec, let me get this right - are you saying you can "hear" engine nozzle position actuators FROM THE GROUND while the jet is FLYING OVERHEAD?

 

it seems like that's what you're saying

[cofcorpse]

Yes!

 

http://forums.eagle.ru/showthread.php?t=124666

 

P.S. we are working on it.

[Rainmaker]

You need to hang around an F-15 unit more. The actuators are heard in flight especially during landing right after they complete there turn to downwind and on final every time the throttles are pulled back! See the YouTube video titled, "C-130's, F-16's and F-15's landing at Nellis AFB." One of the F-15's makes the sound I described IN-FLIGHT!

 

 

Do I? I have 15 years of E model maintenance experience. You sure about that?

 

And by inflight...I am speaking more on the lines of in-cockpit sounds. And yes, when the handle is down, the augs will have full travel(I.E. landing). During normal flight, there is not very much noticable travel unless AB is lit. Otherwise, nozzle maintains close to full-closed.

Edited June 12, 2014 by Rainmaker

[104th_Maverick]

are you saying you can "hear" engine nozzle position actuators FROM THE GROUND while the jet is FLYING OVERHEAD?

 

 

Yeah, as c0ff pointed out to those video's you can hear the actuators over the engines, fair enough those videos are on the ground but you can hear it 100% if you listen out for it! .... Obviously not if the aircraft is to high or far away.

 

c0ff posted a great video in his link of the F-15 sound... here is one of my favorites with an F-16..... yes they are standing right next to it but you can appreciate just how loud the actuator noise actually is!

 

[mytai01]

@mytai....... wait a sec, let me get this right - are you saying you can "hear" engine nozzle position actuators FROM THE GROUND while the jet is FLYING OVERHEAD?

 

it seems like that's what you're saying

 

Yes! That's what I'm saying. If you are at a base with F-15's and watch them you can hear the actuators from the ground. Even if they are 2,000 feet in the air. I've been in the Hawaii Air National Guard for 25 years and usually stay at Hickam billeting for drill. When the 199th FS had it's F-15's I'd always hear it, but neverr knew what the noise was until I saw a video of it up close.

[mytai01]

Do I? I have 15 years of E model maintenance experience. You sure about that?

 

And by inflight...I am speaking more on the lines of in-cockpit sounds. And yes, when the handle is down, the augs will have full travel(I.E. landing). During normal flight, there is not very much noticable travel unless AB is lit. Otherwise, nozzle maintains close to full-closed.

 

I meant I hear it on the ground when the aircraft is overhead. Of the in cockpit videos I haven't been able to tell if they can be heard, since it seems that the air conditioner is the loudest sound in the cockpit.

[mytai01]

Yes!

 

http://forums.eagle.ru/showthread.php?t=124666

 

P.S. we are working on it.

 

At least they know about it. I wouldn't bring it up if I knew they already knew about it.

[strikeeagle]

It's not the actuators that make the sound. It's the air exiting the Convergent Exhaust Nozzle Controller - CENC

[VTJS17_Fire]

Hi ED Team,

 

I tested the flight performance for the F-15C for a tutorial and found some different things ...

 

According to the real F-15C flight manual (Belsimtek used a lot of real text passages for the DCS F-15C flight manual), I tested the fuel flow chart in the sim.

 

I tested with these

 

aircraft settings:

+ 41.000 pounds gross weight (38% of fuel)

+ 4x AIM-7, 4x AIM-9, 1x CL Tank

+ 40.000 feet

+ Mach 0.8

 

weather settings:

+ no wind

+ temperature: 20°C

 

According to the chart, I had to burn 4.800 pounds per hour (80 pounds per minute). But in DCS, my fuel flow indicator indicates a fuel flow of 2.700 pounds per hour) - 56% of what the real flight manual says. AOA was 16°.

 

How accurate is the PFM of the F-15C or did I miss something while testing?

 

 

Thanks in advance,

Fire

DCS_F15C_fuelflow.trk

Edited June 22, 2014 by VTJG17_Fire

[GGTharos]

Did you miss the fact that the F-15 has two engines, maybe?

 

Doing a proper test with a stabilized aircraft at the right GW gets me 2500pph per engine, which is pretty close to the required total 4800pph.

Edited June 22, 2014 by GGTharos