Slow Speed Pitch Instability

[Ski01]

I'm finding it quite difficult to hold a steady speed and attitude at approach speed. There seems to be a bit more pitch change with speed change and also pitch change with power change compared to what I'm used to.

Anyone else notice this? Or it is just me?

 

I'm also not finding the pitch trim much use in finding the stable speed/trimmed attitude on approach.

Practising heaps, slowly getting better, but above points seem valid to me at the moment....

[David OC]

The f18 lands differently to any aircraft most are use to, you need to trim for onspeed aoa once gear and flaps are down.

 

This is the video to watch to get you started.

 

[Ironhand]

I'm finding it quite difficult to hold a steady speed and attitude at approach speed. There seems to be a bit more pitch change with speed change and also pitch change with power change compared to what I'm used to.

Anyone else notice this? Or it is just me?

 

I'm also not finding the pitch trim much use in finding the stable speed/trimmed attitude on approach.

Practising heaps, slowly getting better, but above points seem valid to me at the moment....

The FA-18's FBW system behaves as a trajectory system until you lower your landing gear. From that point on, it is designed to behave as an aircraft with positive pitch stability. That is the point at which you need to trim for the required AoA. Once trimmed, the aircraft wants to maintain that AoA. So a slight increase in speed will cause your aircraft to slowly climb. A slight decrease will cause it to settle.

 

I just bought the FA-18 and installed it this morning. So this is my first time in the cockpit. The attached track is my first very short flight with a landing (at Qeshm Island -Persian Gulf). Assuming it plays back correctly you'll see that, once I'm trimmed, it only takes slight variations in throttle to stay on the slope. I'm posting simply to show that, if you understand what's going on, the aircraft is amazingly stable and simple to fly.

FA-18 First Flight.trk

[Ski01]

thanks guys - I may need to keep tweaking my stick settings and trim method - techniques and accuracy with the M2000 (approach speed plus or minus 2kts when at reference alpha) are not translating to pitch stable flight on approach with FA18 for me at the moment.

[fitness88]

I find when landing with 1/2 flaps I have good pitch control as opposed to landing with full flaps.

[jeffham222]

I find when landing with 1/2 flaps I have good pitch control as opposed to landing with full flaps.

 

+1 on this... Full flaps is sketchy AF...

[majapahit]

I trim very little I wait for the FCS to catch up and let it do the trimming. It way easier.

 

Landing speed is just above stall speed, and this F18 drops like a brick from the air when only a couple of knots from the stall speed.

 

When dropping in altitude because of not concentrated on the speed for that millisecond,

 

I just pulse quite a lot of throttle to see the speed rise into the safe zone and immediately throttle back to not overshoot the speed.

 

You have to be really quit and very focused about the necessity to very quickly recover the planes positioning with the throttle.

 

It is true what the manual and tutorials say, you fly the F18 in primarily with the throttle.

[Baco]

still something changed since the las update, before I was traping ok, nog pitch is over reactive, at low speeds its uncontrolable, y pitches up, then falls like a rock.. i am doing 139Kts, and climbing at 640fpm, then I take off power and falls like a rock at 132 Kts, I dont know, its acting up or is it me?

[Sciacud]

It is true what the manual and tutorials say, you fly the F18 in primarily with the throttle.

"manual" ?? where, please?

[Ski01]

Ok - nice to see I', not going crazy! I'll try 1/2 flap for approach. And also note the need for T/O Trim button prior to launch.

Bolter pitch control seems a bit weird as well.

[Thermal]

Ski - watch the video in the second post. Its really good.

Dont land with half flap - that is usually for takeoff only.

[David OC]

Ok - nice to see I', not going crazy! I'll try 1/2 flap for approach. And also note the need for T/O Trim button prior to launch.

Bolter pitch control seems a bit weird as well.

 

I've started another thread explaining how the F/A-18 works using the onspeed AOA and how you can practice this before trying to land on the carrier so you get the feel for it first and know what to expect from the aircraft when setup correctly.

 

Here is the post and video

 

 

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Edited June 9, 2018 by David OC

[majapahit]

.. then I take off power and falls like a rock at 132 Kts, I dont know, its acting up or is it me?

 

' .. take off power and falls like a rock .. '

is how I hit the stern of Stennis,

 

this is instinctive flaring behaviour that you apply in aircraft that have actual wings.

 

The FA-18 is build for way to high speeds and has dismal wings attached that if one was to use this on the size of a tennis court deck of the Stennis one glides into a flare .. and risk missing the cables.

 

Don't flare don't miss. Do not take off power.

 

If anything pulse that reduction of power that u used to steer down the glide slope, fly the aircraft not the cable. Better hit cable 5 or do a touch (and miss) and go around than any chance of hitting the stern (there is perhaps even a lee effect coded when too low behind the stern of the carrier).

 

What I noticed on actual F18 youtube footage is that the pilot (a pilot? perhaps this differs per squadron and AC type) when wheels touching the deck, actually smashes full throttle,

 

in disregard whether they caught a cable or not (they did of course).

 

There is no decision time for a full throttle calamity, so it appears they build the cables capable to stop the aircraft when at full throttle, and when a cable snaps (or a hook brakes? does that ever happen? or whatever), that's how the pilot has the chance to escape.

Edited June 9, 2018 by majapahit

[JIMJAM]

During my 30 yr rl aviation career I have watched 10s of thousands of landings and especially among the airliners. We could always spot the airforce guys vs the naval pilots. The navy pilots always flew the nose up throttle controlling decent profile with less than smooth touch downs right smack on the numbers as per the F-18 method where most airforce guys were slight nose up, flat to nose down with a healthy flare and as long as the TD was somewhere on the 1st 1/4 of the runway they were happy with it.

Edited June 9, 2018 by JIMJAM

[poochies]

Yeah now I’m getting close to the threshold on carrier right before touchdown and in a split second it’s dropping to stall speed , I need more incremental small throttle adjustments but the pgup and pg down throttle steps don’t work for some reason so one press of the smooth throttle increase or decrease on my control pad is like a 2-3 percent change in rpm

[Eaglewings]

There is no decision time for a full throttle calamity, so it appears they build the cables capable to stop the aircraft when at full throttle, and when a cable snaps (or a hook brakes? does that ever happen? or whatever), that's how the pilot has the chance to escape.

 

I once watched an aircraft carrier documentary on how dangerous working on the deck can be.

Saw so many legs amputation as a result of the stop cable snapping. Strict procedure needs to be followed on the carrier deck.

[Ski01]

Ok - it was me.

Best technique is just to avoid chasing pitch changes and let auto trim hold alpha - however this is only valid as an accurate technique for relatively small variations - as soon as you have large changes you can easily get into pilot induced oscillations where you are chasing the changes across parameters.

 

My initial feel is that the A/P gain may be a bit low and also that the trim change (per click) may be a bit small. Very subjective.

[VFA41_Lion]

Ok - it was me.

Best technique is just to avoid chasing pitch changes and let auto trim hold alpha - however this is only valid as an accurate technique for relatively small variations - as soon as you have large changes you can easily get into pilot induced oscillations where you are chasing the changes across parameters.

 

My initial feel is that the A/P gain may be a bit low and also that the trim change (per click) may be a bit small. Very subjective.

 

yes - as soon as you feel the aircraft even begin to start falling like a rock, you need to be very aggressive using the throttle in regaining control, trimming back to on-speed, and then small movements on the throttle. Otherwise a Seahawk is picking you up.

[David OC]

I made a quick video to help if your struggling with the F-18 setup configuration for landing.

 

 

 

There is a thread HERE with much more info about how the USN land on the carrier and also why they do it this way with many links to all the documents in curly s posts.

 

Have some fun with setting up for the onspeed AOA before trying it out in the high pressure carrier case 1 landing. IRL pilots do hundred of laps before going to the ship. Get a feel for it first so you know what to expect from the aircraft.

 

yes - as soon as you feel the aircraft even begin to start falling like a rock, you need to be very aggressive using the throttle in regaining control, trimming back to on-speed, and then small movements on the throttle. Otherwise a Seahawk is picking you up.

 

When in the pattern you trim for onspeed AOA in LEVEL flight, you should not correct this with trim when flying down the glide slope as it is SET in level flight. Only correct with a little pitch to help resettle the AOA if in very bad turbulence. The aircraft wants to return to this level TRIMMED onspeed setup, you could say it seeks it. Much more info about this in the thread HERE.

 

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Edited June 9, 2018 by David OC

[VFA41_Lion]

what do you do when you are correcting for slow speed indications then? Enlighten me.

[majapahit]

what do you do when you are correcting for slow speed indications then? Enlighten me.

 

You look at you velocity vector 1st, it needs to be on the tower somewhere when at distance, and moving the A/C velocity vector scanning over the deck it should lite your AOA middle circle once in a while.

 

When getting closer you position yourself correctly with very little rudder and roll.

 

In the mean time you check what speed the A/C is stable on a very steady decent,

 

and your main intrument, i find, is your velocity vector that is aiming at, from somewhere a couple of hundred yards from the deck, at a point on the deck that would bring the A/C down at cable #3, by now your AOA middle circle should light a lot,

you're now picking up the ball at the left of the deck and see if you're on the dot.

 

If sinking too fast you should have pulsed the throttle, see the velocity vector go back in the direction you want to go, and before the velocity vector arrives at your aiming point you already easy down on the throttle towards where about your throttle should fluctuate around (all the time).

Edited June 10, 2018 by majapahit

[David OC]

what do you do when you are correcting for slow speed indications then? Enlighten me.

 

In calm winds and a proper pattern why are you getting slow speed indications?

 

Did you watch the turn in the video above?

No pitch here at all, you only correct with the stick for turbulence and to resettle the AOA on the opseed AOA that was setup in level flight.

 

Quote from Curly's (Engineer) post

"The key aspect to understanding why this technique is used is often overlooked and relates to stability. The start of this technique is predicated up on the fact that we are trimmed for level flight before turning on final."

 

So each lap of the ship you are using fuel and getting lighter so your (optimum set) onspeed AOA is when flying level and wings level downwind for each and every lap. This locks in that AOA for that weight and the aircraft will Seek to return to this (onspeed AOA position itself) once coming wings level into the groove, if you re-trim before the groove you have reset the onspeed AOA out of alignment.

 

Much more info about onspeed AOA HERE

 

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Edited June 10, 2018 by David OC

[Eaglewings]

I made a quick video to help if your struggling with the F-18 setup configuration for landing.

 

 

 

There is a thread HERE with much more info about how the USN land on the carrier and also why they do it this way with many links to all the documents in curly s posts.

 

Have some fun with setting up for the onspeed AOA before trying it out in the high pressure carrier case 1 landing. IRL pilots do hundred of laps before going to the ship. Get a feel for it first so you know what to expect from the aircraft.

 

 

 

When in the pattern you trim for onspeed AOA in LEVEL flight, you should not correct this with trim when flying down the glide slope as it is SET in level flight. Only correct with a little pitch to help resettle the AOA if in very bad turbulence. The aircraft wants to return to this level TRIMMED onspeed setup, you could say it seeks it. Much more info about this in the thread HERE.

 

.

 

 

Thanks, David OC for this video.

This method works like a champ for me. I normally would start doing my Onspeed AOA trimming when on my downwind leg as instructed in the in-game tutorial and I have struggled somewhat getting it all fixed up before rolling in on final. By setting Onspeed AOA before entry the pattern and flying it like that till final approach gives me so much stability.

 

I am beginning to think the Approach Power Mode does not need any patch anymore.

Edited June 10, 2018 by Eaglewings

[SCU]

I am beginning to think the Approach Power Mode does not need any patch anymore.

What needs a patch or not is not a matter of opinion; DCS is a simulator, there shouldn't be features to please the players but to be as realistic as the real thing as possible.

[Eaglewings]

What needs a patch or not is not a matter of opinion; DCS is a simulator, there shouldn't be features to please the players but to be as realistic as the real thing as possible.

 

No qualms, let ED do their thing. I am all for the realism.