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Landing


williehayesjr

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Interesting. I do have a bit of curve for the axis but not too much. I find that trimming works well enough and only minor adjustments are needed, but you have to be very on-the-ball with your throttle and glideslope to begin with ... spiky pots would probably throw you off.

Do you see spiking when you have the control display open?

Over the years I've had to gradually increase the dead zone from "0" to "5". So yes. I thought the dead zone took care of it but perhaps not.

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Over the years I've had to gradually increase the dead zone from "0" to "5". So yes. I thought the dead zone took care of it but perhaps not.

 

In my opinion a deadzone itself can make precision input more difficult, especially the larger the deadzone is. When the stick input breaks out of the dead zone it tends to move quite abruptly. Having a very very slight slope response (with the user curve) near the stick center position doesn’t have the ‘jumpiness’ problem that a hard deadzone does. Just my .02 cents.

 

I’ve seen posts about some type of magnet mod to fix the X-52 drift issues. Not sure if it works or is a permanent fix. What does the axis response look like in saitek properties?

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In my opinion a deadzone itself can make precision input more difficult, especially the larger the deadzone is. When the stick input breaks out of the dead zone it tends to move quite abruptly. Having a very very slight slope response (with the user curve) near the stick center position doesn’t have the ‘jumpiness’ problem that a hard deadzone does. Just my .02 cents.

 

I’ve seen posts about some type of magnet mod to fix the X-52 drift issues. Not sure if it works or is a permanent fix. What does the axis response look like in saitek properties?

It's been quite awhile since I've been into the Saitek properties. Just took a look. The "thrust" (Z?) axis doesn't even come down to zero which is interesting since I can cold start the engines. But I just went into the Saitek properties and altered the dead zone for it. As I move it up and down, though, it's movement is jerky. The two joystick axes are also bobbing around a bit.

 

I'll try your curve approach. What you say makes a lot of sense.

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  • 1 year later...
Why can't I ever land on the two rear wheels. I seems as though I always land on one of the rear two wheels? Am I going too fast or too slow (160 knots)?

 

 

I'm resurrecting the thread with some more recent videos to help new Eagle drivers to land.

 

It's been said many times, for regular, no or little crosswind landings:

 

 

- Glide slope: 2.5 to 3°

- Flight Path Marker: positioned on the first skid marks on the runway

- Angle of attack (AOA): 21 units (11°).

- Flare: 20 feet above ground level, to 22-23 units of AOA, wings level

- Airbrake: extended as needed a few seconds before touchdown, or upon touchdown

- Aerodynamic braking after touchdown: 13 to 15° pitch up.

- Wheel braking: after nosewheel down and under 100 knots

 

 

Straight-in landing demo:

 

 

 

 

Overhead break and landing tutorial:

 

 

 

 

(Really) Heavy Landing (and in that case approach parameters are different: more shallow glide slope, 22 or 23 AoA, touchdown early on the runway)

Skip to 0:36 for the F-15.

 

 

 

 

 

Hope it helps!

Steinsch

Flying Virtual F-15s since 1989

YouTube channel: http://www.youtube.com/c/CommanderSteinsch

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I don't know about extending the airbrake before touch-down... it increases your sink rate (as in it generates a downward force). I suppose it could prevent you from balooning.

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I don't know about extending the airbrake before touch-down... it increases your sink rate (as in it generates a downward force). I suppose it could prevent you from balooning.

 

I don't know if it's the manual procedure. However, many videos of F-15s landing show the airbrake being extended slightly before touchdown. I've even seen Japanese F-15s approaching with the airbrake extended, way before touchdown.

 

I don't think extending the airbrake before touchdown is compulsary. But accelerating your sink rate after your flare almost stopped your descent and you're 1 or 2 m above the runway is not necessarily bad in my view. The extra drag helps to have more weight on wheels as soon as you touch down and make your aerodynamic braking less floaty. I imagine a gust of wind may make you leave the ground for a couple of seconds if residual lift is still high.

Steinsch

Flying Virtual F-15s since 1989

YouTube channel: http://www.youtube.com/c/CommanderSteinsch

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My vote for airbrake at or after touchdown.

Exactly 13 degrees nose up - the watermarks even blinks IRL if you hit it right. 15 is risky. Not applicable to strong crosswinds or short runways - you put the nose down early then.

Add the full aft stick after nosewheel down.

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Haha wow beautiful landing Steinsch. One thing I think deserves emphasis is how stable you are on final, just rock solid all the way in. Players should strive for that I think, rather than jinking around looking for the runway.

 

Do you use VR? Significantly increases ability to perceive sink rate, was for me anyway

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I don't know about extending the airbrake before touch-down... it increases your sink rate (as in it generates a downward force). I suppose it could prevent you from balooning.

I don't think that the F-15 speed brake generates a downward force. It's not like spoilers on a wing which reduce lift and besides that, it would make formation flying rather difficult.

 

Furthermore at this low speed and high AoA its effect is already very weak, especially considering the fact that the speed brake automatically retracts at 25 units AoA.

 

Last but not least, the -1 landing distance is only valid with the extended speed brake.


Edited by bbrz

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Haha wow beautiful landing Steinsch. One thing I think deserves emphasis is how stable you are on final, just rock solid all the way in. Players should strive for that I think, rather than jinking around looking for the runway.

 

Do you use VR? Significantly increases ability to perceive sink rate, was for me anyway

 

Thanks, Delta. No VR for me, just a head track. My approaches are not always that smooth, but yes, this is what I try to achieve every time. :)

Steinsch

Flying Virtual F-15s since 1989

YouTube channel: http://www.youtube.com/c/CommanderSteinsch

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My vote for airbrake at or after touchdown.

 

I still think it depends on circumstances. If the pilot feels they're a bit fast just before touchdown, the airbrake might help. Or it might just boil down to pilot preference once all parameters are under control (good flare execution, controlled and low rate of descent, wings level a few meters above the runway.) Here are some videos showing the extending of the airbrake before touchdown:

 

(F-15E)

 

Exactly 13 degrees nose up - the watermarks even blinks IRL if you hit it right. 15 is risky.

 

The USAF manual says 12 to 15°. In my experience in-game, 15° is noticably more effective than 12°. More risky, probably, if the pilot cannot control their attitude well. Worth it and satisfying when you can pull it off quite consistently.

 

Add the full aft stick after nosewheel down.

 

That's very F-18-like! :) In normal conditions (higher speed heavy landing may be another story), I prefer to put weight on wheels after nosewheel is down, as I haven't noticed any difference while testing full aft stick. Maybe it's because the F-15 is way heavier than the F-18 and W-o-W is going to be more effective? I don't know.

Steinsch

Flying Virtual F-15s since 1989

YouTube channel: http://www.youtube.com/c/CommanderSteinsch

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The USAF manual says 12 to 15°. In my experience in-game, 15° is noticably more effective than 12°. More risky, probably, if the pilot cannot control their attitude well. Worth it and satisfying when you can pull it off quite consistently.

I cannot find the source at the moment but 13 was meant as optimal. It's mentioned in DCS FC3 F-15C manual too. I don't like to take risks during SOPs even in the sim as it's just feeding bad habits.

 

That's very F-18-like! :) In normal conditions (higher speed heavy landing may be another story), I prefer to put weight on wheels after nosewheel is down, as I haven't noticed any difference while testing full aft stick. Maybe it's because the F-15 is way heavier than the F-18 and W-o-W is going to be more effective? I don't know.

I would assume after the nosewheel goes down you put more WoW by keeping the stick aft.

 

 

 

If you have some consistent test results for both nose up and nose down airbraking please provide the numbers.

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I would assume after the nosewheel goes down you put more WoW by keeping the stick aft.

Correct. With the required 14° pitch up after touchdown and no wheel brakes, the real F-15C needs a ground roll of 5500ft.

If you need the maximum landing performance you lower the nose immediately after touchdow and the ground roll dramatically decreases to 3500ft.

Usually, you can start braking already with the nosewheel still in the air and you control the pitch down rate with the stabilators.

 

On the F/A-18 things are a bit different because the main gear is considerable more aft of the CG than on land based planes. Hence full aft stick will not, or at least not as easy, keep the nose up.

 

Without groundspoilers/lift dumpers getting the weight onto the wheels is always a problem if you need maximum braking performance.

Applying full aft stick during/after lowering the nosewheel would theoretically increase the braking performance a bit.


Edited by bbrz

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Here are some tests comparing:

 

- Aerodynamic braking at 15°

- Aerodynamic braking at 13°

- Aerodynamic braking (using the stabilizators as airbrakes, progressively then fully aft under 100 kts)

- No aerodynamic braking

 

The point was to:

 

1. Demonstrate that aerodynamic braking works in DCS.

 

It definitely does (for some reason, some people still doubt that).

 

2. Determine differences, if any, between 15°, 13° and 12° aerodynamic braking.

 

In my tests, it took 0.47 NM to bring the plane from touchdown speed to 70 kts, after which wheel brake was applied. 13° took 12% longer, 12° +25% (not shown on the video).

 

Landing with the stick pulled back as much as possible without making the nose go up required 47% more distance. And no aerodynamic braking whatsoever took +62% more than a 15° AB to bring the plane to 70 kts. So full aft stick definitely has some positive effects as draconus mentioned (I'm just wondering know if this is mainly the result of the extra drag or the weight on wheels).

 

I agree with bbrz, the fastest way to stop the F-15 is wheel down as soon as possible and apply wheel brakes right away. It works in-game, and when landing heavy it's often the only choice. But it is my understanding that the crew chief would kick your ass IRL for overheating the brakes.

 

Anyway, the test I did was to demonstrate the effects of aerodynamics on landing in various scenarios, from touchdown to 70 kts. It was by no means to demonstrate which method resulted in the shortest landing roll.

 

 


Edited by Steinsch

Steinsch

Flying Virtual F-15s since 1989

YouTube channel: http://www.youtube.com/c/CommanderSteinsch

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..the fastest way to stop the F-15 is wheel down as soon as possible and apply wheel brakes right away. It works in-game, and when landing heavy it's often the only choice. But it is my understanding that the crew chief would kick your ass IRL for overheating the brakes.

I don't think that the brakes will come even close to overheating during a max performance landing, since the takeoff abort speed can be as high as 180kts (at almost MTOW).

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I don't think that the brakes will come even close to overheating during a max performance landing, since the takeoff abort speed can be as high as 180kts (at almost MTOW).

But the heavy landings speed will not be much lower than that. Otoh we don't have brakes overheating simulated at all.

 

 

@Steinsch: thx, cool video.

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But the heavy landings speed will not be much lower than that

That's correct, but the big difference is the way higher energy when aborting the takeoff. Accelerating vs decelerating, plus the very high pitch attitude during landing.

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So, to my knowlegde aircraft brakes reach their heat limit pretty fast. I would think that maximum brake application during a heavy weight landing or aborting at such a high speed will most likely seal the brake´s fate. I do not think that they can be used again. Such large and heavy aircraft use multi-disk brake systems to absorb the enormous heat. It is very much possible that the tires catch fire in an overheat event.

The Eurofighter is to my knowlegde the only fighter aircraft to use brake fans on the main wheels to decrease cooldown time. So always set the chocks from inward side of the wheel or you´ll get a face full of hot air and carbon dust.

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So, to my knowlegde aircraft brakes reach their heat limit pretty fast. I would think that maximum brake application during a heavy weight landing or aborting at such a high speed will most likely seal the brake´s fate.

It takes about 10min for the brakes/tires to reach their maximum temp after brake application and it's likely that a rejected takeoff at high weight and high speed (and a max performance heavy weight landing) will ruin the brakes and the tires.

 

I was just trying to point out that max braking after a landing at the usually low weight and speed will not necessarily upset the crew chief.


Edited by bbrz

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necessarily upset the crew chief.

 

In the German airforce the brake temperature is checked as soon as the aircraft reached it´s parking position. In our case the crew chief will not be upset at all because he is not the one to inspect or change the wheel assembly. That´s the job of the base maintenance people.

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In the German airforce the brake temperature is checked as soon as the aircraft reached it´s parking position.

And as soon as the plane is at the parking position you can place fans in front of the brakes:)

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In the German airforce the brake temperature is checked as soon as the aircraft reached it´s parking position. In our case the crew chief will not be upset at all because he is not the one to inspect or change the wheel assembly. That´s the job of the base maintenance people.

 

To me, the crew chief is the senior enlisted guy in charge of the maintenance of an aircraft in the Air Force. It is also referred as the plane captain in the Navy. Once the aircraft is on the ground and parked, it's "theirs".


Edited by Steinsch

Steinsch

Flying Virtual F-15s since 1989

YouTube channel: http://www.youtube.com/c/CommanderSteinsch

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Yeah, it's interesting how different nations handle things. In the GAF the crew chiefs are part of a team of two or three line maintenance technicians and responsible for pre- and postflight inspections. They declare the aircraft ready for flight and report any problems. But they are not responsible for any maintenance work.

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Found these videos of Japanese approaching with the airbrake fully extended.

 

I understand that some planes land with airbrakes partially extended because if they need to go around, they can just retract them quickly and already have relatively high engine RPM.

 

Is it the reason the Japanese F-15s do that, and if yes, why don't the USAF Eagles do the same?

 

 

 

Steinsch

Flying Virtual F-15s since 1989

YouTube channel: http://www.youtube.com/c/CommanderSteinsch

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No, this doesn't have anything to do with the engine spool up / go around in case of the F-15.

 

The RPM during the approach is way above the slow acceleration area, and the difference between speed brake in and out is only approximately 2%.

 

The F-15A preliminary manual says to extend the speed brake to assist in speed reduction for the gear extension and the later manuals are stating that the use is optional.

 

The main difference between speed brake in and out is, that with the speed brake retracted, the tendency to float is higher.

 

So if there's a slight ballooning during the flare, you will float along quite a bit longer than with the retracted speed brake. Contrary to the real F-15, the ground effect in the DCS version is (almost?) non-existant.


Edited by bbrz

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