New FM and on speed AOA holding

I have noticed that too because even with trim the nose still rises so there is a problem with the FM. The Hornet has an exact trim number for weight, when set the nose should not be rising at all, instead the FBW should maintain the aircrafts attitude throughout the flight once trim is set. It seems to go through a process where the nose rises, you push it back down to AoA then it rises again and the movement reduces until it holds which is not accurate for FBW. It should be that you set trim and it remains where it is without the nose rising.:doh:

I am not a pilot. My logic to explain the nose rising or falling after setting trim was due to changing airspeed. That was just my guess. Is that not how it works in the real world? Just trying to learn as much as I can.

.... was due to changing airspeed.

You are correct.

Trim does not force an attitude, it controls AOA.

whatever they did to the FM, I'm snatching the 3-wire with more regularity than before.

You are correct.

 

Trim does not force an attitude, it controls AOA.

Thank you!

Warning: Actual real life flight instructor here

That's not technically correct. Trim is an airspeed control, not an AOA control.

In a real airplane, you can set it up in cruise, with an appropriate power setting, and trim off stick pressures. Then if you pull some power off, the airplane will pitch gently down, hands off, and descend at the trimmed speed. From there, add power, and the airplane will pitch up and climb at the trimmed speed. This behavior makes many challenging things about flying a whole lot easier, like flying instrument approaches. Having the airplane help maintain a set speed takes a big load off.

Demonstrating this characteristic is something we do in training, to help the student better understand the trim-power-airspeed relationship.

Now this works in light airplanes and transport-category stuff, which is where my experience is. How well it works in fast-mover jets with FBW and autotrim we'd need to ask Wags.

That's not technically correct. Trim is an airspeed control, not an AOA control.

 

In a real airplane, you can set it up in cruise, with an appropriate power setting, and trim off stick pressures. Then if you pull some power off, the airplane will pitch gently down, hands off, and descend at the trimmed speed. From there, add power, and the airplane will pitch up and climb at the trimmed speed. This behavior makes many challenging things about flying a whole lot easier, like flying instrument approaches. Having the airplane help maintain a set speed takes a big load off.

 

Demonstrating this characteristic is something we do in training, to help the student better understand the trim-power-airspeed relationship.

 

Now this works in light airplanes and transport-category stuff, which is where my experience is. How well it works in fast-mover jets with FBW and autotrim we'd need to ask Wags.

LEX Flies the Hornet in real life. I trust what he has to say. WAGS would be able to answer the question about how it is currently implemented in DCS.

That's not technically correct. Trim is an airspeed control, not an AOA control.

 

In a real airplane, you can set it up in cruise, with an appropriate power setting, and trim off stick pressures. Then if you pull some power off, the airplane will pitch gently down, hands off, and descend at the trimmed speed. From there, add power, and the airplane will pitch up and climb at the trimmed speed. This behavior makes many challenging things about flying a whole lot easier, like flying instrument approaches. Having the airplane help maintain a set speed takes a big load off.

 

Demonstrating this characteristic is something we do in training, to help the student better understand the trim-power-airspeed relationship.

 

Now this works in light airplanes and transport-category stuff, which is where my experience is. How well it works in fast-mover jets with FBW and autotrim we'd need to ask Wags.

I have spoken in great depth on this, please read my many other posts basically stating what you have.

That said, if you break it down: trim changes the angle at witch the horizontal stab hits the relitive wind, that in turn creates a moment about the aerodynamic center such that it forces the angle the wing hits the relitive wind (or AOA) this balancing act between the horizontal stab and wing reaches "equilibrium " at an airspeed. The *best* way to think of trim is that your "trimming to chang equilibrium between the wing and horizontal stab"

If the aircraft has sufficient power such that equilibrium happens with sufficient lift generated, the aircraft will fly lvl, if to little it will seek equilibrium in a dive , to much and it will climb.

It is literaly technically correct. Whats more, the resulting AS where the equilibrium is achieved is the byproduct of the AOA the aircraft seeks. We are both "technically" correct. The confusion probably stems from the fact that AOA is a relitively niche tool where AS is useful in more GA contexts. So AS is typically all the trim conversation needs to cover. The affects of trim is an aerodynamic constant, it works mechanically the same in any aircraft with a dedicated lifting wing that produces a pitching momentum (typically negative), and a stabilizer required to mitigate that pitching momentum. Aerodynamically the same in wings with close to zero net pitching moments (flying wings, etc)

Come chat with us on discord, we talk about all this crazy stuff daily. :)

That's not technically correct. Trim is an airspeed control, not an AOA control.

 

In a real airplane, you can set it up in cruise, with an appropriate power setting, and trim off stick pressures. Then if you pull some power off, the airplane will pitch gently down, hands off, and descend at the trimmed speed. From there, add power, and the airplane will pitch up and climb at the trimmed speed. This behavior makes many challenging things about flying a whole lot easier, like flying instrument approaches. Having the airplane help maintain a set speed takes a big load off.

 

Demonstrating this characteristic is something we do in training, to help the student better understand the trim-power-airspeed relationship.

 

Now this works in light airplanes and transport-category stuff, which is where my experience is. How well it works in fast-mover jets with FBW and autotrim we'd need to ask Wags.

With FBW it works faster and better than an aircraft without FBW IRL. Being in PA mode the FBW knows the FPM is in the bracket and the donut and maintains it, with Auto-throttle it should be even better.:pilotfly:

The ground effect thread was closed, so I'll ask here:

Why am I losing my AOA at the ramp? I'm not making any big throttle changes, and I'm holding the stick steady, but as I cross the ramp my AOA gets wonky and I end up fast and flat trying to grab the wires. I've caught myself trying to save a bad approach with the stick before, but just now I deliberately tested not moving the stick and still find the aircraft creeping fast. User error or related to the ground effect issue?

The ground effect thread was closed, so I'll ask here:

 

Why am I losing my AOA at the ramp? I'm not making any big throttle changes, and I'm holding the stick steady, but as I cross the ramp my AOA gets wonky and I end up fast and flat trying to grab the wires. I've caught myself trying to save a bad approach with the stick before, but just now I deliberately tested not moving the stick and still find the aircraft creeping fast. User error or related to the ground effect issue?

Have you tried it on an airbase?

The ground effect thread was closed, so I'll ask here:

 

Why am I losing my AOA at the ramp? I'm not making any big throttle changes, and I'm holding the stick steady, but as I cross the ramp my AOA gets wonky and I end up fast and flat trying to grab the wires. I've caught myself trying to save a bad approach with the stick before, but just now I deliberately tested not moving the stick and still find the aircraft creeping fast. User error or related to the ground effect issue?

Which ground effect thread are you referring to, the recent reverse ground effect thread?

If so, the thread has been moved to the bug section and marked as reported.

The reverse ground effect would've had the opposite effect from what you're describing.

If you're referring to a normal ground effect I haven't noticed any when trapping on the boat and I do pay attention to ball, AOA, line up and... just occasionally VVI.

I do see a slight "cushioning" when landing on runways. I haven't really dwell on it too much so I might be exaggerating a little:smilewink:

Now... something just occurred to me regarding reverse effect... just want to confirm with folks that tested this thoroughly. It is only present with gear up, is it? Or is it speed related?

The ground effect thread was closed, so I'll ask here:

 

Why am I losing my AOA at the ramp? I'm not making any big throttle changes, and I'm holding the stick steady, but as I cross the ramp my AOA gets wonky and I end up fast and flat trying to grab the wires. I've caught myself trying to save a bad approach with the stick before, but just now I deliberately tested not moving the stick and still find the aircraft creeping fast. User error or related to the ground effect issue?

.... if you have a vid it would help.

Understand this is in the realm of "technique " and "that pilot sh!t"..

You shouldn't be "trying to grab a wire " , nor should you need to really be "holding the stick steady " .

Fly the ball all the way to touchdown, if ya catch a wire ya catch it, if ya dont ya don't. Either way, the arrestment should be a surprise, as it is the byproduct of a good pass and that pass is your focus, not trying to catch a wire. It is analogous to the trigger pull on a gun, the firing of the round will be a surprise and hitting the target is a byproduct of trigger pull technique. Trying to catch a wire is tantamount to yanking on the trigger at the last minute of a shot. Whats more and contrary to popular beliefe, LSOs grade the pass, what wire you catch is not factored in at all.

(In the context of a non auto throttles pass)

What i mean when i say "should not be holding the stick steady " is, you shouldn't have to "fly the ball with the nose " or rigidity hold the stickin a position. The aircraft should be seeking on speed by way of how trim works and that will keep the stick where it needs to be by nature of that. If the aircraft requires pitch inputs by the pilot you either do not have it trimmed properly or you are not flying the ball with power alone. Only thing you should need to hold steady is AOB. When i illustrate this to individuals for the first time i point out that if you keep AOB under control with your knees and fly the ball properly with the throttle, ya dont need to even hold the stick. Disclaimer: this demonstration is only 100% do-able in a very controlled environment like say, a Simulator, a game, or on a day with zero gusts, perfect seas and natural wind right down the angle. You may find YouTube real life vids with seeming contradicting information.

Try Isolating those variables and reevaluate.

All that said, ground effect in fuselage loaded aircraft is very hard to perceive. Only time i ever realized it was when i made a flaired landing to save a seeker on a pod that would not lock and even then it was barely noticeable. Otherwise i had to intentionally look for it. (This is quite anicdotal) On a carrier the aircraft easly punches through any ground effect that may happen. The burble, however, is another story.

Hope this helps :)

You shouldn't be "trying to grab a wire " , nor should you need to really be "holding the stick steady " .

Fly the ball all the way to touchdown, if ya catch a wire ya catch it, if ya dont ya don't. Either way, the arrestment should be a surprise, as it is the byproduct of a good pass and that pass is your focus, not trying to catch a wire. It is analogous to the trigger pull on a gun, the firing of the round will be a surprise and hitting the target is a byproduct of trigger pull technique. Trying to catch a wire is tantamount to yanking on the trigger at the last minute of a shot. Whats more and contrary to popular beliefe, LSOs grade the pass, what wire you catch is not factored in at all.

 

Hope this helps :)

Super helpful! And maybe I misspoke - looking back on a previous pass I saw my AOA go fast right as I hit the ramp. I think on that pass I deliberately pitched forward to try and save myself from floating past the wires, definitely the wrong technique and your analogy is a good one. So after that I tried to make sure I didn’t make any similar movements. When I say “hold steady” I mean I gave 0 pitch input once I got trimmed on-speed (ok. I confess I made a little rolling in and out of my turn, but definitely no input once in the groove) I was not holding AOA with the stick or anything like that, she was trimmed and had a good AOA all the way down to the ramp. At that point the aircraft pitched forward, again I’m 99% certain with no pitch input from me (for thee purposes of this test I was overly focused on not pitching) and my AOA dropped into the 6’s. Judging by the responses I think this is still something I did somewhere without realizing it and isn’t probably a bad habit I need to break, but since others had mentioned a funky ground effect in the sim I wanted to see if anyone else had this happen.

Can you get control input to show in a .trk?

... i am just guessing also, assuming the game is acurate and isolating the pilot as a variable first. The game can still be outa wack. I am developing some hardware and dont have the means to properly test the ground effect yet.

Find us on discord, there are many others that can work on this with you.

Now... something just occurred to me regarding reverse effect... just want to confirm with folks that tested this thoroughly. It is only present with gear up, is it? Or is it speed related?

That's an interesting question. Just did a few tests with surprising results.

160kts flaps half, gear down, above ground effect. 4.5°AoA, 85%N1 > ground effect 3.5°AoA, 83%N1 > no pitch down. No difference with the gear up except for a 4% lower N1.

160kts flaps full, gear down, above ground effect. -0.5°AoA, 85%N1 > ground effect -2.5°AoA, 84%N1 > no pitch down. (1% thrust difference between half and full flap?)

160kts flaps auto, gear up, above ground effect. 9°AoA > ground effect 8°AoA, no pitch down.

Did another test at 220kts (flaps auto, gear up) and suddenly the pitch down occured, but only at a very low altitude. Estimated 10-20ft. Due to the rapid onset of the pitch down I wasn't able to get reliable stable AoA values.

Flaps should always be Full for landings, ground effect should never happen as it does not occur IRL.

Trim works through the FBW by holding AoA once set in PA, it is an exact number in accordance with aircraft weight including fuel.

Flaps should always be Full for landings

Almost always... Well, the real world part has been extensively explained by Lex.

bbrz was trying to narrow down this reverse ground effect bs...

...ground effect should never happen as it does not occur IRL

Where did you get this info from? Looking at the wing span, loading, its position, flaps/flaperon size and deflection angles, it's rather easy to calculate that there is ground effect.

That it isn't noticable/effective during unflared landings, where you are descending rapidly through the ground effect, is a different story. Maybe even the FBW masks it.

Where did you get this info from? Looking at the wing span, loading, its position, flaps/flaperon size and deflection angles, it's rather easy to calculate that there is ground effect.

 

That it isn't noticable/effective during unflared landings, where you are descending rapidly through the ground effect, is a different story. Maybe even the FBW masks it.

No.

ground effect should never happen as it does not occur IRL.

I think you should read this.

I am referring to the Hornet, does it effect the aircraft adversely on approach...no!

I am referring to the Hornet, does it effect the aircraft adversely on approach...no!

Erm, that's exactly what I said. With the no flare landing technique, it doesn't. If you try to grease her on with a high power setting you would most likely notice it.

Same goes for the DCS version, since the required AoA and thrust is lower in ground effect.

Not my video so I hope this is cool to post here, but captures what I’m describing. Several pretty good approaches. If you watch the indexer just prior to touchdown it goes into the red fast arrow every time.

The ground effect issue has been around for a while. ED has said that the engineer responsible for the FM will return to working on it when he is done with more pressing projects.

I posted this in January: https://forums.eagle.ru/showpost.php?p=3760047&postcount=73

The one thing I did wrong, which I learned after making the gifs, was not to anticipate touchdown with the throttle. This has no affect on the present topic however.

(Lex, in his discord, rightly was skeptical of my flying ability and so his good criticism had me thoroughly testing this out until I was flying the last few hundred feet with my hands completely off the stick, and I included the axis indicator as well as the top part of the stick to be sure.)