FAQ for F-15 AFM Development

[strikeeagle]

I'd love to have a go in a professional simulator. You've flown the eagle in real life as well? What 'feel'/feedback' was the sim missing as opposed to the real thing?

 

Regarding the PRCA, IMO the CSBPC could be simulated in Matlab or Labview. The flight control system is a bunch of block diagrams in the virtual sense. I'm not saying it would be a walk in the park to simulate but it's far from impossible.

 

I was a Crew Chief on Strikes at SJ and I taught the jet at Sheppard so I was lucky enough to get two rides.

 

What I mean about feel and feedback is the same I experience during sim checkrides at my company. Real air loads across a flight control surface translate into feel or feedback. Seat of the pants flying of you will. You can't feel real turbulence, air loads, G's, or any of the other tactile feedback in sims.

 

Like I said, fighter guys haul and jam on that stick pretty good. The CSBPC of the 15 interprets those inputs and gives the pilot what he/she wants within the envelope while maneuvering. However, within THIS sim, you can "fly" well within the envelope and still lose control.

 

Something I've learned flying (for real) w/old F-4 and F-15 drivers..."when you here the beeps, use your feet".

[SinusoidDelta]

I was a Crew Chief on Strikes at SJ and I taught the jet at Sheppard so I was lucky enough to get two rides.

 

What I mean about feel and feedback is the same I experience during sim checkrides at my company. Real air loads across a flight control surface translate into feel or feedback. Seat of the pants flying of you will. You can't feel real turbulence, air loads, G's, or any of the other tactile feedback in sims.

 

Like I said, fighter guys haul and jam on that stick pretty good. The CSBPC of the 15 interprets those inputs and gives the pilot what he/she wants within the envelope while maneuvering. However, within THIS sim, you can "fly" well within the envelope and still lose control.

 

Something I've learned flying (for real) w/old F-4 and F-15 drivers..."when you here the beeps, use your feet".

 

 

I envy of you, I would empty my bank account for a ride along!

 

I don't think we'll be able to simulate everything in my lifetime. The lack of feel is true with racing simulators as well.

 

Us armchair pilots can't feel anything, so we have to keep our eyes glued on the HUD. We have no perception of roll rate aside from watching instruments and the horizon. This makes determining the point where the aircraft is about to depart very difficult, especially when it happens so quickly and in conditions where it should not. One thing to consider though, the F-15 requires 20lbs. of aft force to command 8G! (See the image below). You really had to work for those high G maneuvers. The force required to pull the Thrustmaster Warthog full aft is probably *less* than the breakout force (deadzone) on the real F-15!

 

 

My understanding is the F-15's ARI intended to eliminate the need for flying with your feet at high AOA or adding left yaw with right stick, mostly because constantly dancing on the rudder pedals was such a burden for F-4 pilots.

Edited August 5, 2015 by SinusoidDelta

[strikeeagle]

I envy of you, I would empty my bank account for a ride along!

 

I don't think we'll be able to simulate everything in my lifetime. The lack of feel is true with racing simulators as well.

 

Us armchair pilots can't feel anything, so we have to keep our eyes glued on the HUD. We have no perception of roll rate aside from watching instruments and the horizon. This makes determining the point where the aircraft is about to depart very difficult, especially when it happens so quickly and in conditions where it should not. One thing to consider though, the F-15 requires 20lbs. of aft force to command 8G! (See the image below). You really had to work for those high G maneuvers. The force required to pull the Thrustmaster Warthog full aft is probably *less* than the breakout force (deadzone) on the real F-15!

 

BINGO!! Exactly my point! :thumbup: When I was getting checked out in the 737 last month is was tough to figure out how much pull of the yoke was needed during rotation or the landing flare. All I knew to do is do it slow. When I finally flew the jet, it all came together when I could feel the feedback in the yoke and seat along with hearing the outside ques.

 

My understanding is the F-15's ARI intended to eliminate the need for flying with your feet at high AOA or adding left yaw with right stick, mostly because constantly dancing on the rudder pedals was such a burden for F-4 pilots.

 

Yes, but when you need a high roll rate at low airspeed and high alpha, you can stomp on the rudder. There is a scene in the "Cock" video where the pilot pulls on the stick, uses one burner, and stomps on the rudder to achieve that roll rate.

 

IIRC, the ARI won't give FULL rudder deflection using the stick. The DCS developers to a great job w/that feature in the game. Evident when you move the stick left and right and the rudders move.

Edited August 5, 2015 by strikeeagle

[Svend_Dellepude]

Deleted because it was rubbish!

Edited August 17, 2015 by Svend_Dellepude

[Fishnuts]

I was a Crew Chief on Strikes at SJ and I taught the jet at Sheppard so I was lucky enough to get two rides.

 

I'm at SJ now! I'm a tower controller and I find out next week if I'm going to pilot training. I'm just trying to reach escape velocity out of Shady J. It's not the worst place in the AF by any stretch, but it's not my favorite.

[Flamin_Squirrel]

Real air loads across a flight control surface translate into feel or feedback.

 

Most (all?) hydraulic flight controls are non-reversible are they not?

[Nerd1000]

Most (all?) hydraulic flight controls are non-reversible are they not?

 

Most aircraft with boosted controls have some system intended to provide artificial feel. This video covers the system in the F-4, along with the SAS and autopilot.

 

${1}

Edited September 12, 2015 by Nerd1000

[Flamin_Squirrel]

Most aircraft with boosted controls have some system intended to provide artificial feel. This video covers the system in the F-4, along with the SAS and autopilot.

 

 

Sure, but that's completely different.

 

strikeeagle spoke about "loads across a flight control surface translate into feel or feedback". In this case, the stick/rudder forces you experience are directly related to the force experienced by the control surfaces (if the plane was on the ground and you moved a control surface, it would move the stick in the cockpit - the controls are reversible).

 

With "artificial feel"... well the clue is in the name. The stick/rudder forces you experience are nothing to do with what the control surfaces are experiencing; they are artificially generated, usually in proportion to speed/stick displacement.

 

(the video link didn't work btw)

[Nerd1000]

Sure, but that's completely different.

 

strikeeagle spoke about "loads across a flight control surface translate into feel or feedback". In this case, the stick/rudder forces you experience are directly related to the force experienced by the control surfaces (if the plane was on the ground and you moved a control surface, it would move the stick in the cockpit - the controls are reversible).

 

With "artificial feel"... well the clue is in the name. The stick/rudder forces you experience are nothing to do with what the control surfaces are experiencing; they are artificially generated, usually in proportion to speed/stick displacement.

 

(the video link didn't work btw)

 

Yeah, I tried to fix the video but it doesn't seem to want to cooperate. Here's a link:

 

Artificial feel indeed does not actually reflect the forces on the control surfaces, but our sim setups typically lack even the artificial feel system (beyond the spring in the stick). Maybe that is what strikeeagle is trying to say?

[NineLine]

Yeah, I tried to fix the video but it doesn't seem to want to cooperate. Here's a link:

 

Artificial feel indeed does not actually reflect the forces on the control surfaces, but our sim setups typically lack even the artificial feel system (beyond the spring in the stick). Maybe that is what strikeeagle is trying to say?

 

[ youtube ] EXsTlmokAlQ [ /youtube ] - no spaces

 

or

 

paste EXsTlmokAlQ and then highlight it and click your youtube button then you get this:

 

[Nerd1000]

Ahh, so you just put in the end of the youtube link. Thanks Sith.

[strikeeagle]

Most (all?) hydraulic flight controls are non-reversible are they not?

 

I can't say all for sure because it depends on how the system was designed. For the F-15 definitely a no.

 

Sure, but that's completely different.

 

strikeeagle spoke about "loads across a flight control surface translate into feel or feedback". In this case, the stick/rudder forces you experience are directly related to the force experienced by the control surfaces (if the plane was on the ground and you moved a control surface, it would move the stick in the cockpit - the controls are reversible).

 

With "artificial feel"... well the clue is in the name. The stick/rudder forces you experience are nothing to do with what the control surfaces are experiencing; they are artificially generated, usually in proportion to speed/stick displacement.

 

(the video link didn't work btw)

 

I meant feel or feedback either through artificial or between the surface and control. No matter the pilot can tell how the jet is performing through control inputs and the responses.

[SinusoidDelta]

Sure, but that's completely different.

 

strikeeagle spoke about "loads across a flight control surface translate into feel or feedback". In this case, the stick/rudder forces you experience are directly related to the force experienced by the control surfaces (if the plane was on the ground and you moved a control surface, it would move the stick in the cockpit - the controls are reversible).

 

With "artificial feel"... well the clue is in the name. The stick/rudder forces you experience are nothing to do with what the control surfaces are experiencing; they are artificially generated, usually in proportion to speed/stick displacement.

 

(the video link didn't work btw)

 

See my post #252. The job of the FCS is to provide the pilot the same aircraft response when applying the same amount of stick deflection throughout the flight envelope.

[strikeeagle]

Now what?

 

[Sweep]

Oooooooooooooh!

 

That's sexy.

[GGTharos]

Used for long range ID, and ECCM :)

[Xenovia]

is Belsimtek still considering making the F-15 cockpit fully clickable?

[5e EVC Chappy]

is Belsimtek still considering making the F-15 cockpit fully clickable?

I was wonbdering the same. What is the status of AFM development?

 

Thanks,

[Sryan]

I was wonbdering the same. What is the status of AFM development?

 

Thanks,

 

It has PFM, just no ASM, only SSM

[Wizard_03]

http://forums.eagle.ru/showpost.php?p=2295479&postcount=72

 

This was January 2015 and there's been a couple hints here and there since, but we don't know if its currently in development or just planned for future.

 

They have certainly evolved the FM considerably. Even since the PFM was released so I'm sure that's a good sign and we've seen some new features being sneaked in such as TO Tim, toggle-able SAS channel switches, Blinking strobe lights ect. So its still being worked on.

 

I think its more a matter of when then If.

[5e EVC Chappy]

OK, thanks!

[wilbur81]

FM tweaks with 1.5.5?

 

Hey, Eagle Drivers.

 

Anyone noticed some tweaking to the 15C since latest 1.5.5 beta/release versions? I've been playing around with it and roll rates below 500 kts seem slower (which may be more realistic?) I don't have a problem with the changes if we're closer to realty, I'm just wondering if I'm imagining things?

[GGTharos]

Unloaded rolls should be 250deg/s above 300kts-350, IIRC. The CAS controls the roll rate so it doesn't get too fast.

[wilbur81]

Unloaded rolls should be 250deg/s above 300kts-350, IIRC. The CAS controls the roll rate so it doesn't get too fast.

 

That's great. So, in answer to my question: did any changes to the fm come with 1.5.5? :)

[GGTharos]

That I don't know. Cofcorpse? Are you here Cofcorpse? :D