Flying an ICLS approach

[Hippo]

When configured flaps full, gear down, on AoA and trying to maintain a stable approach (glide) path (even with no wind) I notice that:

 

1. There is a very long delay between moving the throttles and the path changing (by watching the FPM and descent rate).

 

2. Even after setting power, there are long, slow oscillations with the FPM and DR taking a very long time to settle (if ever).

 

Q: What's the latest opinion on these, is the FM finalised in this respect? These behaviours seem unrealistic to me (i.e. it can't be this much hassle IRL).

 

I have gone to a lot of trouble to adjust throttle curves so I have very fine control over thrust - however, even the minutest motion of the throttles translates to considerable (and highly delayed) changes and oscillations of FPM position and descent rate.

 

By stable I mean descent rate and flight path marker position not varying.

 

****

 

I usually take the time to search before posting, but on this occasion I suspect the matter has been discussed often and at length - and simply couldn't bear to trawl through it all. I was hoping that someone who keeps up with this can just clear it up for me with a quick answer. Thanks.

Edited April 25, 2020 by Hippo
Answers are going somewhat off-topic and not answering my question.

[Greyman]

By coincidence, I've just done a perhaps less than perfect Case III recovery, but largely managed to keep it on the glide slope for the whole approach, by "walking the throttles". That is, making regular and minor adjustments, in turn, to each of the two throttle levers, anticipating and countering the rises and falls, before they happen.

 

I can't say for sure that the length of the delay, between moving the levers and seeing the desired outcome, is entirely accurate, but it does feel good when you get it right. :)

[Theodore42]

Hi!

 

I'm not exactly understanding your problem, but it kind of sounds like you're having an issue controling input?

 

Are you using a HOTAS? If not, you're going to have a really had time using the throttle precisely in DCS :(

 

If you do have a HOTAS you might want to try turning off the user curves to see how that feels.

When I got the F-16 I messed with the curves a lot to try to make it "feel" right, but it never did. Then, on advice from forums, I turned off the curves, and it feels great now. Can't explain it :)

 

But like I said, I'm not exactly understanding your problem. Perhaps the nature of my confusion will help you clarify?

[Hippo]

By coincidence, I've just done a perhaps less than perfect Case III recovery, but largely managed to keep it on the glide slope for the whole approach, by "walking the throttles". That is, making regular and minor adjustments, in turn, to each of the two throttle levers, anticipating and countering the rises and falls, before they happen.

 

I can't say for sure that the length of the delay, between moving the levers and seeing the desired outcome, is entirely accurate, but it does feel good when you get it right. :)

 

I have an X52 Pro, so only 1 axis, I have read others also mention "walking the throttles" so perhaps having two axes helps somewhat.

 

Don't get me wrong, I can certainly manage to land, and my adjusted throttle curve does make it easier. But it seems almost impossible to hold a constant descent rate, and it takes far too long for thrust changes to compensate. I find it implausible that this would be the case IRL, as it would be too risky for the pilot's safety.

 

Night case IIIs are more challenging with the latest OB now that the carrier lights don't come on. :)

Edited April 24, 2020 by Hippo

[Greyman]

I have an X52 Pro, so only 1 axis, I have read others also mention "walking the throttles" so perhaps having two axes helps somewhat.

 

Don't get me wrong, I can certainly manage to land, and my adjusted throttle curve does make it easier. But it seems almost impossible to hold a constant descent rate, and it takes far too long for thrust changes to compensate. I find it implausible that this would be the case IRL, as it would be too risky for the pilot's safety.

 

Night case IIIs are more challenging with the latest OB now that the carrier lights don't come on. :)

 

With just one throttle axis, you will probably be forced to make twice as many adjustments, each of which will make twice the difference to the total thrust than you perhaps need. It's not impossible and I am sure that there will be some super-skilled sim-pilot that can do a far better job with one axis than i can do with two, but 2 axes should certainly make it easier.

 

As for the lights, for after-dark case IIIs, i just try and bisect the island and the "ball", which are lit up. Suffice it to say I don't always succeed and, perhaps thankfully, i only play in SP. :)

[Theodore42]

I'm still not EXACTLY understanding your issue.

 

I have an X-52 pro also and don't have a problem landing. If you could post a replay of yourself landing maybe that would help diagnose what's going on?

 

Here is me landing the hornet in max heat (less thrust available) and turbulance at "100" (100 * 0.10 ft/s):

 

 

(at about 3:30) You'll have to look at the gauges to see what I'm doing with the throttle.

 

But if I can fly the ball to the deck with thrust nerfed because of heat and my glideslope reckt by turbulence with an X-52.... I mean, you gotta be doing something not right.

Edited April 24, 2020 by Theodore42

[Hippo]

I'm still not EXACTLY understanding your issue.

 

 

Thanks for replying, but I think you might've misunderstood / misread my original post. I've gone over it, and I think I have explained myself clearly.

Edited April 25, 2020 by Hippo

[Theodore42]

I have an X52 Pro, so only 1 axis, I have read others also mention "walking the throttles" so perhaps having two axes helps somewhat.

With just one throttle axis, you will probably be forced to make twice as many adjustments, each of which will make twice the difference to the total thrust than you perhaps need. It's not impossible and I am sure that there will be some super-skilled sim-pilot that can do a far better job with one axis than i can do with two, but 2 axes should certainly make it easier.

Why does it matter that the X-52 is only 1 axis.

The only thing I can think of... is that you guys are talking about........ trying to control each of the engines separately?

Ya don't do that while landing.

Only during start up and if something breaks. Some people will micro the throttle with asymmetric loadouts and stuff but that's really just being pedantic.

Thanks for replying, but I think you might've misunderstood / misread my post. I've gone over it, and I think I have explained myself clearly.

Clarity is important because someone might get the impression that you need a two axis HOTAS to land in the Hornet, and as everyone can see from the video I posted, it is demonstrably false.

[Greyman]

Like I said, in my post, some people will be able to cope with one axis, better than i can with 2 and you are apparently proof of that.

 

As for using the throttle levers individually, RL pilots use that technique for landing, and AAR, so i guess you are just special.

[Hippo]

Thanks for your replies, but this is going slightly off topic. Maybe I should've have phrased my original post differently.

 

Perhaps forget landing for now. Try and fly the F-18 straight and level with full flaps, gear down, and on speed AoA. Then read my first post re stable flight.

 

My questions were are the engine spool up times realistic, i.e. it takes ages between a minor throttle change and the aircraft reaction. And after the reaction the aircraft fpm oscillates slowly for a long time before settling. You will find it very difficult if not impossible to fly straight and level. Are these behaviours realistic?

 

I think this has been discussed repeatedly on these forums for some time, and I was just wondering if a consensus had been reached?

Edited April 25, 2020 by Hippo

[Greyman]

I vaguely remember @Lex Talionis, a RL pilot who does some excellent videos, stating that the delay seemed a little too long, compared to the real Hornet, from his first impressions, but not sure of whether his view has changed or whether there is a bug or not.

[Flamin_Squirrel]

My questions were are the engine spool up times realistic, i.e. it takes ages between a minor throttle change and the aircraft reaction. And after the reaction the aircraft fpm oscillates slowly for a long time before settling. You will find it very difficult if not impossible to fly straight and level. Are these behaviours realistic?

 

I think this has been discussed repeatedly on these forums for some time, and I was just wondering if a consensus had been reached?

 

No idea how realistic it is as I'm no Hornet pilot, but it is perfectly possible to fly straight and level in DCS. I expect your technique is probably lacking anticipation - your pitch is probably deviating a fair amount before you react, so you make large power corrections to catch it, which just makes things worse.

 

You need to make frequent small corrections IMMEDIATELY at the point you see pitch move away from where you want it. As a training exercise try flying straight and level, find a point on the HUD frame in line with the horizon, and keep it at there.

[toutenglisse]

Theodore42 on your video I can see what other exp. users saw on my own "wrong" way to do (so now I do it, at least for this point, correctly) :

Your "E" bracket is totally moving up and down during all final approach, instead of being Always perfectly centered with the Velocity vector. That is meaning you are using pitch which is wrong (it would only be correct for small adjustment for Desc.Rate before being on glide slope if you were using ATC approach mode).

You should trim AOA when full falps down so bracket is centered stable and then never pitch again until touch down, only adjusting descent rate by throttle input (walking it being the right way to compensate spool).

 

Hippo I also have single throttle, but when in landing config and trimmed AOA everything is totally stable and easy with throttle - going straight or turning - if not for you I only think about bad trim because it was hard for me before doing right.

 

Best to show a little video so users can quickly help I think (not me I don't have RL knowledge except gliders, but sometimes I've learn Something from others so I can say something).

 

Also the way ICLS is showing where to go, the way you have to anticipate its slowing reaching right path, is a matter of usage - before having good habbit of it it's easy to overshoot, overcorrect etc...

[Hippo]

No idea how realistic it is as I'm no Hornet pilot, but it is perfectly possible to fly straight and level in DCS. I expect your technique is probably lacking anticipation - your pitch is probably deviating a fair amount before you react, so you make large power corrections to catch it, which just makes things worse.

 

You need to make frequent small corrections IMMEDIATELY at the point you see pitch move away from where you want it. As a training exercise try flying straight and level, find a point on the HUD frame in line with the horizon, and keep it at there.

 

How realistic it is is precisely what I was hoping to get an informed opinion on.

 

You did notice I said FLAPS FULL, GEAR DOWN and ON AOA? Are you telling me that you can keep the aircraft straight and level in this config (constant 0 fps vertical speed indication), without seeing the behaviours I described, and without constantly jiggling the throttles?

Edited April 25, 2020 by Hippo

[Hippo]

Theodore42 on your video I can see what other exp. users saw on my own "wrong" way to do (so now I do it, at least for this point, correctly) :

Your "E" bracket is totally moving up and down during all final approach, instead of being Always perfectly centered with the Velocity vector. That is meaning you are using pitch which is wrong (it would only be correct for small adjustment for Desc.Rate before being on glide slope if you were using ATC approach mode).

You should trim AOA when full falps down so bracket is centered stable and then never pitch again until touch down, only adjusting descent rate by throttle input (walking it being the right way to compensate spool).

 

Hippo I also have single throttle, but when in landing config and trimmed AOA everything is totally stable and easy with throttle - going straight or turning - if not for you I only think about bad trim because it was hard for me before doing right.

 

Best to show a little video so users can quickly help I think (not me I don't have RL knowledge except gliders, but sometimes I've learn Something from others so I can say something).

 

Also the way ICLS is showing where to go, the way you have to anticipate its slowing reaching right path, is a matter of usage - before having good habbit of it it's easy to overshoot, overcorrect etc...

 

is very interesting, mainly because it's very clear at a decent res and you can see a lot of detail (hud on ddi, engine indications).

 

It seems like the engine response is quicker to me.

 

Notice how much the pilot is using the thrust levers.

 

(Admittedly - bad weather, superhornet.)

Edited April 25, 2020 by Hippo

[Greyman]

Yes. Maybe fire up a free flight mission, get to below 250kts and deploy gear and flaps. With throttles at idle, wait for speed to drop to say 150kts, using airbrakes if necessary, and then add some gas, at the same time as trimming the nose up to get the flight vector indicator aligned with the centre of the "E" bracket. You should then just need to adjust your throttle(s) to find a speed that keeps you on the level and with the desired AoA. Retract aibrakes btw,

 

That speed will depend upon your aircraft's weight, but you'll find it quick enough.

[Ramsay]

FLAPS FULL, GEAR DOWN and ON AOA? Are you telling me that can keep the aircraft straight and level in this config (constant 0 fps vertical speed indication), without seeing the behaviours I described, and without constantly jiggling the throttles?

 

I can keep the aircraft straight and level without too much jiggling of the throttles but I guess that'd be dependent on what you call "too much" or how well you anticipate your throttle changes.

 

Walking (what you call jiggling ?) the throttle becomes part of normal flying and second nature.

 

This video has the control indicator displayed, so you can compare his throttle inputs to you own.

 

[Bagpipe]

I don't really think the plane is designed to be flown straight and level with full flaps and gear down, as this is a landing configuration by way of design. I'm reading this thread and not understanding what the problem is. It almost feels like you are not grasping the physics involved?

And without ever flying the real aircraft (??) i doubt you ever fully will. (not trying to be rude here).

 

The throttles are supposed to be walked(jiggled), and the aircraft is supposed to descend in landing config....

[Flamin_Squirrel]

You did notice I said FLAPS FULL, GEAR DOWN and ON AOA? Are you telling me that you can keep the aircraft straight and level in this config (constant 0 fps vertical speed indication), without seeing the behaviours I described...

 

Yes.

 

...and without constantly jiggling the throttles?

 

No. Constant corrections are required.

[Hippo]

The throttles are supposed to be walked(jiggled)

 

(real life) Source for this claim, please.

Edited April 25, 2020 by Hippo

[Hippo]

Let me attempt to ask my question again.

 

Set the aircraft with GEAR DOWN, FULL FLAPS on speed AOA. Attempt to fly as straight and level in this configuration as possible.

 

Once nearly there, say you have a negative vertical velocity (vv), you make a small thrust increase and wait...

 

1. it now takes several (around 3) seconds for this thrust increase to cause a change in fpm (flight path marker) motion / vv.

 

2. the fpm very slowly oscillates up and down around a central point, rather than settling

 

It seems to be impossible to end up with 0 vv, without constant throttle corrections, no matter how small.

 

This is what I see in the sim, does the real aircraft behave in this way?

 

The behaviour I see in the descent is the same in that I can't maintain a constant rate of descent - I see the same oscillations once I stop moving the throttle. I would expect that the vv would settle to a constant value (on a calm, no turbulence or gusts, day).

Edited April 25, 2020 by Hippo

[G B]

Regarding number 1: the reaction time depends on the magnitude of the VSI. There were always be some lag, but it could range from small to large depending on a number of factors. If your VV is .5 degrees below the horizon, lag will be minimal. If you’re screaming down at 2000 fpm, lag will be greater. This “lag” is why Magic Carpet (now called PLM) was invented for the Rhino and F-35.

 

Regarding number 2: there should not be “oscillations.” It is difficult to find a “perfect” power setting that will hold 0 VSI over a period of time. IRL, nobody just sets the throttle and then just leaves it. Small power corrections will be required (albeit subconsciously) to maintain 0 VSI in the landing configuration while straight and level.

[Greyman]

at around 3:15, for evidence that pilots do "walk the throttles". He doesn't say it explicitly, but you should see from the movement of his hand that he isn't going to be moving both levers together on approach.

[Hippo]

at around 3:15, for evidence that pilots do "walk the throttles". He doesn't say it explicitly, but you should see from the movement of his hand that he isn't going to be moving both levers together on approach.

 

 

Thank you - that was very interesting and certainly backs up your point.

 

 

EDIT: But... doesn't it also suggest that the response to the throttle changes must be almost instant?

Edited April 25, 2020 by Hippo

[G B]

Walking the throttles is a very common technique. But it is technique. Not ALL pilots use it.