Pitch UP when Carrier Launch with Auto Flap

[Deano87]

It's been said above that there's lots of video showing takeoffs in auto-flaps.

 

I haven't searched myself so I've only seen the one presented here, and in the one presented here, the aircraft pitches up immediately after takeoff into a loop. Exactly the same behaviour that the OP described.

 

Anyone got a link to a takeoff W/ auto-flaps that is followed by level flight with the auto-flaps maintained ?

 

Thats irrelevant: If you do an Flap Auto takeoff with a cold start jet the aircraft flies normally - Trims to 1G. If you do a Flap Auto takeoff with a Hot start jet you end up with a jet massively out of trim - I guarantee that the display pilot is not spending the whole display fighting with an aircraft that is trimmed to 3G.

[Svsmokey]

K . I'm gonna use the F/A-18C Block 20 pocket checklist so we have a common test standard for anyone who wishes to replicate .

[Svsmokey]

Well....using the checklist indicated , F/A-18C Block 20 pocket cold start , taxi and takeoff , I can replicate Deano's results . Only deviations from checklist were didn't turn on radar , obogs , radios , and of course , not setting flaps to half . I ran this test twice , with the same result - a normal (albeit extended) takeoff .

I also ran the hot start takeoff , with flaps in auto , and got the un-commanded pitch , again twice . (Plus once hours ago)

 

I am a little leery of this checklist . It didn't call for a control check , which i do in any aircraft , and it calls for takeoff with the ATT select in standby . Rightly or wrongly , i always set that to "auto" . However , in the interest of a test standard that anyone can can replicate , with only the deviations noted , i conformed to this checklist . Just for the hell of it , I tried setting the ATT select to standby on one of the hot starts , with no change noted . Gonna test again tomorrow with Natops checklist , but until then , I can confirm Deano's results .

 

(Edit) Review of Natops pocket checklist does confirm both my reservations regarding the above checklist .

Edited October 26, 2018 by Svsmokey

[GhostB]

At what point can we perhaps instead of trying to prove or disprove the behavior based off if it is or is not in a startup checklist as being procedure, and just ask a simple question.

 

Does this seem like intended behavior from such a late model hornets FCS? Forget if its procedure, would this potentially dangerous behavior, requiring the pilot to take his hands off the hands to correct, be intended in a real plane.

If this is intended realistic behavior, I could almost guarantee it'd be documented and ample cautions would be stated somewhere in your hallowed manual.

 

Seriously, the fact it behaves different between a cold and a hot start alone, should be enough for people to drop their checklists and begin to consider that they might need something a bit more concrete to prove this one either way.

[shagrat]

I agree. And I was never shouting "YOU MUST FIX THIS NOW!!! LITERALLY UNPLAYABLE!" but rather I'm trying to have a discussion about a FCS anomaly which clearly other people are experiencing.

 

Now that we have that point out of the way.

 

 

 

So let me fully understand what your saying. When you say "like it should" you mean you've tested it in both a hot start on runway and a cold start and it behaves the same? And what is that behaviour exactly?

No, it does the pitch up after hot start (spawning a pre started plane) and deliberately put flaps to auto.

What I meant was if we follow the checklist where are we at that state "pre-taxi"?

Now, if you do a cold startup, everything is fine. No problems, correct?

Easiest fix for the bug in line with realism, would be to disable hot-start...

 

Another question would be, what is the procedure to make a flaps on auto start IRL?

You assume it is just setting flaps to auto, but maybe the behaviour on hot start is correct and maybe you need to have the spring on the stick like the blue angels, reset the FCS again and trim specifically to do it IRL?

As long as no F-18C pilot chimes in and says how he would do it with the real plane or we get an authentic procedure listing the correct steps for a "auto" flaps take off, this is just a guessing game, not a bug report.

 

The only factual data provided is the NATOPS manual, that tells you how to do proper startup and how to take off. That is with flaps set to half.

If the behaviour after hot start, or after cold start is correct, is simply assumption.

 

It's nice to show a video with a auto flaps take off but what was the procedure the pilot followed?

One wild guess is, he maybe switched to half during or shortly before rotation?

What was his trim?

Did he reset the FCS before leveling out?

Or maybe he took off and pushed the stick full forward, while resetting the FCS?

 

We don't know! :dunno:

 

So can you tell 100% sure the behaviour on hot start is the bug or are you just assuming it is a bug, because you assume it is just required to switch to auto flaps and take off.

Edited October 26, 2018 by shagrat

[macedk]

This is just so silly guys....

 

"hey if I remove the rear wing on my gt2rs porsche, it can't iot it loose in high speed corners"

 

Well the car dosen't work as intended without the rear wing.

 

The plane is not intended to be at auto flaps on carrier launch. In real life the plane would never be launched on purpose.

 

You guys are smarter than this silly discussion.

[backspace340]

Easiest fix for the bug in line with realism, would be to disable hot-start...

 

Seriously? Surely the easiest fix is just to make the FCS consistently behave in a non-lethal way, as it does when taking off from a cold start with the flaps in auto. Just because we don't know for certain doesn't mean we're incapable of using some common sense.

 

Answer me this - if you were a test pilot and you found this behaviour in the real Hornet, would you report it as an FCS issue, or would you just think 'well the NATOPS tells me not to, so I'll just keep that to myself'?

[shagrat]

Seriously? Surely the easiest fix is just to make the FCS consistently behave in a non-lethal way, as it does when taking off from a cold start with the flaps in auto. Just because we don't know for certain doesn't mean we're incapable of using some common sense.

 

Answer me this - if you were a test pilot and you found this behaviour in the real Hornet, would you report it as an FCS issue, or would you just think 'well the NATOPS tells me not to, so I'll just keep that to myself'?

 

Please read my whole post and tell me which behaviour is correct. Do you have a checklist or an F-18C pilot comment describing the correct behaviour? If no, you just assume, what should or should not be correct.

 

We don't know, what behaviour is correct/realistic when deviating from the checklist.

 

The videos show only there is a way to take off with auto flaps set on starting the take off roll. No details on fuel state and Center of gravity, no input if the pilot needs to counter the pitch with stick, or if he simply switches flap to half shortly before or while rotating (to reduce drag during the roll). No idea if you need/should reset the FCS after takeoff etc. etc. just a lot of assumptions and guessing...

[GhostB]

Hey, I'll give you the benefit of the doubt and assume you are not incapable of putting together an well reasoned argument, and your just are having trouble understanding and translating English. Let me try help.

 

"The only factual data provided is the NATOPS manual, that tells you how to do proper startup and how to take off."

 

The only dactual data provided is the NATOPS manual eh.... So.. so we know HOW your meant to do a proper take-off, but doesn't that manual say "Caution; Taking off with the poorly named AUTO-Flaps will endanger your aircraft and challenge your ability to maintain stable flight"

 

Does it? Does it say "Taking off with the incorrect flap setting will induce X, sorry we probably should of caught that during development, and fielding the platform for a couple decades, we fixed a bunch of other FCS issues but decided we liked this one"

 

Because I'm pretty damn sure the FCS isn't setup in such a fashion to attempt to kill NAVY pilots, they're generally pretty protective of their expensive personnel and equipment.

 

So how about instead of quoting how its meant to be done, as if that somehow eliminates what does happen if its done 'incorrectly'. You don't have the level of detailed documentation that ED has through its partners and contacts... Do you? You have redacted, absent of most of the combat systems flight manual that tells you have to turn the lights on. The correct way of doing it, does not tell you what will happen when you do it incorrectly.

 

It in no way, proves or disproves the accuracy of this flight characteristic... Does it?

So how about instead of telling the guy hes simply doing it wrong, when hes acknowledged that its not the correct way of doing it but the behavior still seems unlikely and inaccurate...

 

We instead get this passed along to the development team, who have the ability to consult their licensed documents and their 1st hand sources, such as F18 pilots, who have a tad more knowledge of the flight characteristics than simply jumping up and down on the spot, blue in the face going "BUT THAT ISN"T HOW ITS MEANT TO BE DONE"

 

If you have trouble understanding any of the words I have used, or the concepts I have tried to express, please feel free to ask for further clarification I will be glad to provide further assistance.

Edited October 26, 2018 by GhostB

[backspace340]

Please read my whole post and tell me which behaviour is correct. Do you have a checklist or an F-18C pilot comment describing the correct behaviour? If no, you just assume, what should or should not be correct.

 

We don't know, what behaviour is correct/realistic when deviating from the checklist.

 

The videos show only there is a way to take off with auto flaps set on starting the take off roll. No details on fuel state and Center of gravity, no input if the pilot needs to counter the pitch with stick, or if he simply switches flap to half shortly before or while rotating (to reduce drag during the roll). No idea if you need/should reset the FCS after takeoff etc. etc. just a lot of assumptions and guessing...

 

Great, so, seeing as how neither of us know what the correct behaviour is, instead of telling ED what to do about it how about we let them review the tracks and decide whether it's something they want to fix or not? Perhaps when they've done that, they can let us know their decision by saying [NOT A BUG] or [REPORTED] in the title and we can stop discussing this to death.

 

In fact, even better - this duplicate thread was made in the Bug forums and it's been marked [ALREADY REPORTED], not [NOT A BUG], so there we go - it's a bug according to ED. Case closed: https://forums.eagle.ru/showthread.php?t=223126

Edited October 26, 2018 by backspace340

[Skwinty]

This thesis analyzes the recent Version 10.7 Operational Flight Program (v10.7

OFP) Flight Control System upgrade to the F/A-18A-D (legacy) Hornet fighter aircraft.

This developmental program endeavored to improve high angle-of-attack (AOA)

maneuverability while vastly reducing the aircraft’s susceptibility to sustained out-ofcontrolled flight events.

Although the original F/A-18 Hornet, designated F/A-18A through F/A-18D, has

been acclaimed for its departure resistance as well as its exceptional maneuverability as a

fighter aircraft, the model, in actuality, has suffered from significant losses due to out-ofcontrolled flight (OCF) mishaps. Since its development in the early 1980s, eighteen

Hornets have been lost to a particular OCF mode called “Falling Leaf”, including eight

aircraft crashed since 1999. With no improvements, 10 additional aircraft, at a cost of

$40 million each, were forecast to be lost.

[Skwinty]

https://fas.org/man/dod-101/sys/ac/docs/990414-ART-Super-Hornet.htm

 

https://trace.tennessee.edu/utk_gradthes/2372/

Edited October 26, 2018 by Skwinty
added link for previous post

[Deano87]

Did he reset the FCS before leveling out?

Or maybe he took off and pushed the stick full forward, while resetting the FCS?

 

FCS reset doesn’t solve the problem after takeoff, please feel free to go try. And in all the videos I’ve seen he doesn’t go to half flap at any point during the takeoff because the ailerons never droop. Only the inboard flap section which happens because of the AOA demand of the initial pull.

Edited October 26, 2018 by Deano87

[shagrat]

FCS reset doesn’t solve the problem after takeoff, please feel free to go try. And in all the videos I’ve seen he doesn’t go to half flap at any point during the takeoff because the ailerons never droop. Only the inboard flap section which happens because of the AOA demand of the initial pull.

As I said, I was making wild guesses. We need a subject matter expert or official procedure to solve that.

Seems ED will investigate...

[majapahit]

It's not procedures that are being discussed here.

 

DCS FA-18 is not a plane, is a monstrous number crunching automaton put together by talented software developers that tries to emulate as closely as possible the real life FA-18 in a personal computer.

 

OP is just trying to help these developers achieve their goal. He found a behavior in this DCS module that may, or may not, depart from the real plane; so he is reporting it to ED so that they can take a look at it, if that's even possible accounting for their extremely busy to-do list.

 

The "correct procedures" is the high level part of the game, the "let's pretend" part.

 

I find really sad how people can not make the distinction between the mundane code implementation and debugging side of things and the pretending game, and tend to heavily disrupt relatively trivial threads like this. Also sad how the computer science jargon word 'bug' has completely lost its original meaning.

 

It's just a little bit of the implementation in code of the FCS, which is effectively a reverse engineering emulator of an existing software, that needs a check if possible. And if it's not possible because there is 10,000 items with higher priority it's fine aswell.

 

 

Exactly

 

 

Fly your DCS F-18 Beta release according to what works for now and which is frighteningly similar (pun intended) to real life,

and have the coders add ACLS landing capability (my second choice), air-to-ground MK missiles and a TGP screen (would be my first choice), but who am I. Just another guy enjoying himself with a joystick and a screen.

 

Don't bother trying to fly outside the available envelope, since you have to factor time and resources, though no one can stop you and report this,

but going on and on about this why would you do that?

 

Why is grass green?

Why is it raining and no taxi cab will stop for you?

Why did you forget your dentist appointment and now you're miserable?

Why?

Edited October 26, 2018 by majapahit

[Skwinty]

FCS reset doesn’t solve the problem after takeoff, please feel free to go try. And in all the videos I’ve seen he doesn’t go to half flap at any point during the takeoff because the ailerons never droop. Only the inboard flap section which happens because of the AOA demand of the initial pull.

 

Perhaps the pilot engages FCS Override to better control pitch in this flapless take off.

[BitMaster]

Hitting your thumb 4 times with a hammer and thinking the 5th hit won't hurt is stupidity.

 

 

Albert Einstein

[Deano87]

Hitting your thumb 4 times with a hammer and thinking the 5th hit won't hurt is stupidity.

 

 

Albert Einstein

 

Yeah but hitting your hand with two hammers which should be identicle and getting totally different results is pretty interesting ;)

[shagrat]

In fact, even better - this duplicate thread was made in the Bug forums and it's been marked [ALREADY REPORTED], not [NOT A BUG], so there we go - it's a bug according to ED. Case closed: https://forums.eagle.ru/showthread.php?t=223126

 

In fact that just means they have put it on the list of things to investigate. As I am sure they will need to discuss this with their subject matter experts.

 

I'll simply stick to normal take offs, that work pretty good for me, until we get a chapter on "auto-flaps-take-off" in the F-18C manual.

[Skwinty]

I can replicate the auto flaps take off exactly as the video in a hot aircraft with FCS GAIN OVERIDE engaged and 0 degrees on stabilator, 0 degrees flap and 3 degrees LEX.. Once airborn, rear flaps extend to half. No out of control longitudinal pitch.

[shagrat]

I can replicate the auto flaps take off exactly as the video in a hot aircraft with FCS GAIN OVERIDE engaged and 0 degrees on stabilator, 0 degrees flap and 3 degrees LEX.. Once airborn, rear flaps extend to half. No out of control longitudinal pitch.

 

Sounds like it depends on procedure not "fixing bugs", then... funny. ;)

 

...and the difference to cold start is still something to look at, and a final word from an expert would be cool.

[Skwinty]

Sounds like it depends on procedure not "fixing bugs", then... funny. ;)

 

...and the difference to cold start is still something to look at, and a final word from an expert would be cool.

 

Did you read links I posted earlier? Listen to the experts and procedures. Both make for informative reading.

I can find more.;)

[shagrat]

Did you read links I posted earlier? Listen to the experts and procedures. Both make for informative reading.

I can find more.;)

Honestly, I did not read every linked document... I was a bit upset, by the assumptions driving a major part of this discussion.

 

I was pretty sure after the warning indications, a simple flick on the flap switch and ignoring the warnings, couldn't be the correct procedure. ;)

[Svsmokey]

Did you read links I posted earlier? Listen to the experts and procedures. Both make for informative reading.

I can find more.;)

 

I did , actually . Well , skimmed . The first sounds like it was written by a program officer , whose PR approach and false logic sent that one straight to the garbage .

The second is the kinda stuff i enjoy reading . (Call me weird) . I downloaded it for a thorough read when i have time .

Have to say , tho , unsure how either relates to this thread . In any case , thanks for the latter .

[Flamin_Squirrel]

Sounds like it depends on procedure not "fixing bugs", then... funny. ;)

 

...and the difference to cold start is still something to look at, and a final word from an expert would be cool.

 

Honestly, I did not read every linked document... I was a bit upset, by the assumptions driving a major part of this discussion.

 

I was pretty sure after the warning indications, a simple flick on the flap switch and ignoring the warnings, couldn't be the correct procedure. ;)

 

It seems to me the only person making assumptions is you. You are in no greater position of knowledge than anyone else in this thread.

 

And no-one in this thread (that I can see) is saying "this is definitely a bug". Someone made an observation about something that they couldn't recreate in the DCS module. Thankfully the guys at ED are more open minded that you, so it's now being looked into.

 

Apologies the above sounds personal, and I tried not to be; I just don't understand why you're so sure no bug exists.