Case I: How to respond to pitch up from flaps?

[Habu_69]

Gear first, flaps at 200-220. Gotta try it.

[flx54]

I am having a hard time to get the plane stabilized as well. I know, that in real aircraft, plenty of things happen "aerodynamicallywise" when you extend flaps. Its a combination of lift and drag which changes. The Power curve (Lift/drag or Thrust required/drag) changes. Every aircraft is different and usually built in a stable way. At least civil aircraft are. Military jets, so i do believe, can be a lot different.

 

Just tried some level flight and config changes. Not too easy to handle at all. I have the feeling, that the hornet is a bit unstable even at level flight. To check that i made very very small inputs on the roll axis and noticed, that it will not come back to wings level by its own. Cant say if that is a true hornet behaviuor, but from my understanding, a stable aircraft should return to wings level. More or less. But never increase bank angle once the stick is untouched.

 

Interesting to know, what a real hornet pilot would comment on this...

[aaron886]

I am having a hard time to get the plane stabilized as well. I know, that in real aircraft, plenty of things happen "aerodynamicallywise" when you extend flaps. Its a combination of lift and drag which changes. The Power curve (Lift/drag or Thrust required/drag) changes. Every aircraft is different and usually built in a stable way. At least civil aircraft are. Military jets, so i do believe, can be a lot different.

 

Just tried some level flight and config changes. Not too easy to handle at all. I have the feeling, that the hornet is a bit unstable even at level flight. To check that i made very very small inputs on the roll axis and noticed, that it will not come back to wings level by its own. Cant say if that is a true hornet behaviuor, but from my understanding, a stable aircraft should return to wings level. More or less. But never increase bank angle once the stick is untouched.

 

Interesting to know, what a real hornet pilot would comment on this...

 

This is massively oversimplified, is all. You'd be correct about small civil airplanes but the transfer of knowledge doesn't really hold for jets like the Hornet, mostly because it's fly by wire. The transient pitch effects when you switch to HALF/FULL are because the computer is driving the TEFs and aileron droop to fixed values, and no longer automatically positioning them for optimal cruise/maneuvering flight. Additionally, and perhaps more importantly, the computer switches from trimming for 1G to trimming for a fixed angle of attack. I'm not sure DCS handles that transition perfectly, but the point is that the transition itself is real and does occur in the actual jet.

 

So the condensed answer to your problems is that you have to take over the trimming duties when you switch to flaps HALF/FULL. You can anticipate that the DCS Hornet will make that transition with too high of an AOA trim setting to begin with, so be prepared to trim forward immediately. As you decelerate, you'll need aft trim to settle in to on-speed AOA.

 

Also, the roll behavior is normal. The F/A-18 is a fly-by-wire fighter and the FCS is designed to give it neutral static roll stability, making it both predictable and more maneuverable. The idea being that if the pilot commanded a bank angle, he probably wanted it to stay that way. Most fighters exhibit relaxed roll stability (and stability in general,) but with fly-by-wire it is possible to maximize the benefits of that instability, and give an almost uncanny artificial stability in its place.

[majapahit]

..

Also, the roll behavior is normal. ..

Having said this, and seems to be correct, I think I thick I remember that ATC throttle hold is still WIP with flaps down half and full, for with flaps out ATC really does nothing other than confuse..

[Flamin_Squirrel]

Stop making it harder than it needs to be by lowering flaps when straight and level. Do it while banked, it's so much easier.

[flx54]

This is massively oversimplified, is all. You'd be correct about small civil airplanes but the transfer of knowledge doesn't really hold for jets like the Hornet, mostly because it's fly by wire. The transient pitch effects when you switch to HALF/FULL are because the computer is driving the TEFs and aileron droop to fixed values, and no longer automatically positioning them for optimal cruise/maneuvering flight. Additionally, and perhaps more importantly, the computer switches from trimming for 1G to trimming for a fixed angle of attack. I'm not sure DCS handles that transition perfectly, but the point is that the transition itself is real and does occur in the actual jet.

 

So the condensed answer to your problems is that you have to take over the trimming duties when you switch to flaps HALF/FULL. You can anticipate that the DCS Hornet will make that transition with too high of an AOA trim setting to begin with, so be prepared to trim forward immediately. As you decelerate, you'll need aft trim to settle in to on-speed AOA.

 

Also, the roll behavior is normal. The F/A-18 is a fly-by-wire fighter and the FCS is designed to give it neutral static roll stability, making it both predictable and more maneuverable. The idea being that if the pilot commanded a bank angle, he probably wanted it to stay that way. Most fighters exhibit relaxed roll stability (and stability in general,) but with fly-by-wire it is possible to maximize the benefits of that instability, and give an almost uncanny artificial stability in its place.

 

Alright. A very good post to my problem. Thanks for the info. Will have a closer look on the FCS. I am used to trim for speed and not for acceleration forces. ;)

[Deano87]

Guys try this. Gear and flaps to FULL when you get to 250kn mid break (DURING THE TURN) and then 3 seconds of up trim will get you in the AoA ballpark.

 

Works for me.

[Chuck_Henry]

Guys try this. Gear and flaps to FULL when you get to 250kn mid break (DURING THE TURN) and then 3 seconds of up trim will get you in the AoA ballpark.

 

Works for me.

 

This is what works for me, as well. Remember, pulling G equal to 1% of your indicated airspeed is just a guideline. In reality, you can and should pull more or less aggressively as you need to for spacing or wind purposes. Entering the initial at 350 knots, I typically pull 3.8 to 4.0 G and back that off a little passing 300, so that I do end up at 250 by the halfway point as opposed to 20 degrees from downwind heading which is what usually happens if I only pull using the 1% rule. Then I drop the gear and flaps and immediately shallow my angle of bank to about 40-45 degrees so I'm not too tight to the runway. Above all else, remember that no self-respecting Hornet pilot uses the speed brake in the break!

[majapahit]

Guys try this. Gear and flaps to FULL when you get to 250kn mid break (DURING THE TURN) and then 3 seconds of up trim will get you in the AoA ballpark.

 

Works for me.

If one checks FCS auto-trim with the Ctrl-Enter indicator on, and clearer than the FCS numbers readout , one can notice the FCS trim that accommodates a certain level flight with certain speed and flaps up while downwind, is fairly maintained after banking into final break with flaps up, because of computation lag (somewhat likely) or because of computation of the - hard - bank (which would be excellent design).

Edited January 13, 2019 by majapahit

[majapahit]

What I started doing lately to exercise CASE 1 (1.5) is training a CASE 1 short break/SHB, starting form the deck, immediately of the deck call Stennis, left hand to 600ft, flaps up at 600 for a sec to stabilize alt @ 200-230kts, immediate final break, ask Stennis to land, dirty up, land on the deck with the landings lights (at the moment release version),

 

in a deep dark night,

 

 

as if being in a flight sim IFR training with all views off, only relying on HUD, HSI, landing lights @ 90 in pitch dark, ball at final.

 

It teaches you real fast to get your numbers right (this is simulating a sim only, of course).

Edited January 14, 2019 by majapahit

[DeltaMike]

Guys try this. Gear and flaps to FULL when you get to 250kn mid break (DURING THE TURN) and then 3 seconds of up trim will get you in the AoA ballpark.

 

Works for me.

 

I think this is the thing, for the sim.

 

Last night in muliplayer I tried running the pattern at sane speeds, midfield break at 250. Dump flaps on the downwind at 145 and the jet falls out of the sky. Get on the throttle and it points to the moon. Rinse and repeat. (I thought about you, OP, with newfound empathy.)

 

Until they fix the low speed handling, I think we are better off dumping flaps at 250. Which, if you're gonna do that, you could flip the switch 40 miles out if you want, they come out at 250 anyway.

[Flamin_Squirrel]

Until they fix the low speed handling...

 

Sorry I'm going to be blunt here: what needs fixing is your flying. Fly the proper pattern and you won't get any problems.

Edited January 13, 2019 by Flamin_Squirrel

[TheD3vil]

Stop making it harder than it needs to be by lowering flaps when straight and level. Do it while banked, it's so much easier.

 

Perhaps the reason why people drop the flaps while straight and level is because it's on a Wags tutorial video?? Because, this and following directions is how I learn.

 

[Wizard_03]

So the second you take the flaps out of auto below 250 knots the FCS switches to take off and landing mode, and it tries to get you close to on speed. It now requires trim to adjust it, based on your jets loading and weight.

 

That's the "pitch up" your all complaining about, and the reason NATOPS has you drop the flaps and gear during the break turn (with boards out if necessary) So #1 you won't notice it since your already yanking on the stick and #2 you'll drop speed so fast that by the time your out of the break you've stabilized On speed from the FCS change and the drag induced by the gear and flaps, and your in a nice steady manageable descent down to 600 ft.

Edited January 14, 2019 by Wizard_03

[majapahit]

.. Dump flaps on the downwind at 145 ..

Why ever would you want to do that? Don't do that. As far as I can tell, light, empty, flaps down level and stable is around 200 kts, higher if heavy, a lot higher if very heavy. The FA-18 can "fly" below that speed with flaps up, thanks to the massive engines, for instance after launched, or doing acrobatics, about from 155-175 when light, which is safe with military or afterburner trust and pitch up, which puts you in a "rocket envelope" with no necessity of any wings. Hard banking in final you watch you descend rate and give whatever throttle necessary to maintain you descent path, which sometimes, in need of correction (f.i. you see you're going to be low merging final when miscalculating you descend because you're out too far whilst being short to the intercept also and are in immediate need of maintaining level flight), will dip you in the 'rocket envelope' as well.

Edited January 14, 2019 by majapahit

[Flamin_Squirrel]

Perhaps the reason why people drop the flaps while straight and level is because it's on a Wags tutorial video?? Because, this and following directions is how I learn.

 

 

Sure. You'd need to do the same for a straight in for Case III, or perhaps an emergency scenario.

 

I just question why when people here keep saying there's a more common and easier way, why keep persisting with the less common harder method. They certainly shouldn't blame the flight model until they've tried the published procedure.

[aaron886]

I don't know why you're saying that's more common.

[majapahit]

Perhaps the reason why people drop the flaps while straight and level is because it's on a Wags tutorial video?? Because, this and following directions is how I learn.

 

You can see Wags turns in downwind @ 680ft, when he puts gear down flaps down and probable throttling down, he still rises to 740ft, thus this was not 'perfect procedure', gear down below 250 @240 OK, but then he could have waited for a sec and then when flaps down whilst throttling down he would have these 3-4 seconds so he could cross 200kts full flaps and level all at the same initial 680ft, now already decelerating within the full flaps envelope, descending towards his ~ 137kts final speed which is the on level speed on final when light.

 

For the mentioned final break turning in clean and switching full flaps in that break,

 

this is an abbreviated final break what only jet fighter pilots do as a hot (and unofficial, very not NATOPS) shortcut,

 

which most likely is only allowed for proven and tested pilots for its risks (or one would be send off, how unlikely is this ever to happen, anybody knows how this works?)

 

one has to correct such a hard bank by adding throttle and the harder the break the higher the corrected speed for the required vertical descent rate (as in ~200-230kts) so to not drop out of the air because of having highly reduced horizontal surface and thus also when before the final turn the excessive residue thrust has to be anticipated to manage a projected substantial increase of lift when leveling the aircraft to horizontal and this also needs to be anticipated accordingly.

Edited January 14, 2019 by majapahit

[Flamin_Squirrel]

I don't know why you're saying that's more common.

 

Because it is. It's what you do for a Case I recovery, the topic of this thread.

[SMN]

Real video.

Gear down and flaps full - at the same time.

There are no (I do not see) big movements of throttle and stick in the same time ...and there is NO lift!

Edited January 14, 2019 by SMN

[Flamin_Squirrel]

Because they drop the flaps in the break, where the pitch-up is less noticeable.

[majapahit]

Real video.

Gear down and flaps full - at the same time.

There are no (I do not see) big movements of throttle and stick in the same time ...and there is NO lift!

he has very little throttle breaking left and after the time the flaps are full he is below 200kts, no throttle, no lift.

one knows he's down throttle because he throttles up later on final turn

 

he actually flies level flight on the 90 ~170kts or so, so he started out about 1.4 from the boat, I'd say.

[Pikey]

I'm not sure I like that particular video as a reference. Here are the reasons.

 

He's likes a little 5 degree climb after the initial to break, to 1000+ft radar and the initial speed is lower than 350 based on the subsequent numbers as the video starts.

 

Our pilot drops both at 235kts, (he's 20 or so knots slower half way through the break than I am), trims, then the video is cut and suddenly he's at 800 after a pitching down moment.

 

Video cuts again in the downwind and he's still not onspeed at abeam, he's still slowing, letting the AoA come to him rather than rushing to meet it.

 

It's not our aircraft.

 

However, the lift moment and reasons for giving it may suggest the flaps deploy a bit too fast in the sim, as was said earlier, that at faster speeds when deployed, you get more lift, so I think either of the two previous comments work, deploying flaps whilst in the break lessen the effect of the float, or deploying them later reduces the impact.

 

I do recognise you can definitely get a hard to manage "float" when deploying the flaps in certain configurations, but it's somewhat hard to use that video as any evidence that it's not happening in an F-18C, and in any case, if you fly enough, you just work around how the sim performs without regard for watching a video side-to-side.

 

I'd humbly offer that the zoom climb on the bolter climbout is way harder to deal with.

Edited January 14, 2019 by Pikey
various mistakes

[Akula]

I'm not a pro at case 1 by any stretch of the imagination. My orbits are too big and break turns, down wind leg.. All that stuff I suck at BUT, I did realize that when I set my flaps to full during my massively huge break turn it works better if I use more throttle than stick to keep things smooth as pie. Check all the carrier landing videos on YouTube and you'll see that the pilot does far more throttle work than he does stick work until he's on final and then he's manipulating everything as much as he needs to to catch that 3rd wire. In the end it's all about get the the jet on the deck safely and no matter what you read you need to figure out what works best for you.

[Flamin_Squirrel]

I'm not a pro at case 1 by any stretch of the imagination. My orbits are too big and break turns, down wind leg.. All that stuff I suck at BUT, I did realize that when I set my flaps to full during my massively huge break turn it works better if I use more throttle than stick to keep things smooth as pie. Check all the carrier landing videos on YouTube and you'll see that the pilot does far more throttle work than he does stick work until he's on final and then he's manipulating everything as much as he needs to to catch that 3rd wire.

 

I'm not sure I understand this bit; are you saying you're adding throttle during the break, or when you're downwind/turning to final? If you're adding throttle during the break, that's why your orbits are so big. Throttle should be idle and speedbrake out.

 

In the end it's all about get the the jet on the deck safely and no matter what you read you need to figure out what works best for you.

 

Yes, it's definitely a sim to do with as we each choose.

 

If someone's struggling, either their proceedure or their technique (or sometimes even both) isn't right. IMO it's generally better in the long run to learn the correct proceedure and work on your technique than try to come up with a technique that works for the wrong proceedure. Assuming they want to, of course. Hopefully that makes sense!