Landings - I don't get it

[Denco]

I flare to 5 degrees at about 20 feet of radial altitude with the speed of vref on a  3 degree G/S. Sometimes the landings are smooth but sometimes the plane smashes the ground. Why?

Edited February 19, 2017 by Denco

[Morten]

Well, flaring too early will cause a hard landing (airspeed drops close to a stall), so will flaring to late (high vertical speed).  Also at what point you idle the throttles is important. Just before you flare, your vertical speed will be about 700 fpm, or in other words 10-15 feet/sec, so timing the flare just 1 sec +/- wrong will put you 10-15 feet away from where you should be causing a non-smooth landing.  Jan can give you much better advice than I can, but I bet he'll tell you a smooth landing is not something real pilots aim for because that can cause you to land too far into the runway (float) which might be dangerous, tail strike, cost extra fuel/time missing exit's, wear on brakes etc.

Edited February 19, 2017 by Morten

[Denco]

I decrease my throttle at 10ft. 

[frumpy]

The pitch-up depends on the weight and speed. At low speed you can pull higher.

For a normal landing, 5° is too much, I think. Jan did a description of

the landing in one of the tutorials, check them out. I think it was like 3° plus from the

approach attitude, but I'm not sure.

 

You might want to try to get a feel for the delays between the altitude callouts:

 

Edited February 19, 2017 by frumpy

[Denco]

30 minutes ago, frumpy said:

I think it was like 3° 

Yea but the G/S is 3 degrees so on flare I pitch only 2 degrees to get to 5 degrees. Doesn't seem that much to be honest. 

[frumpy]

Glideslope angle is not your pitch. A steeper glideslope means less pitch angle.

 

Read the tutorial (I think it was the first one), check out a 737 AOM, check out

the landing videos.

[Litjan]

If you come in on the ILS, your approach angle (the path the plane takes) is usually 3 degrees. So you must pull up BY 3 degrees to enter level flight - not TO 3 degrees. In other words, notice your attitude as you fly down the ILS (it might be anywhere from 0 to 5 degrees nose-up) and then ADD 3 degrees to it when you flare.

Example: During approach you determine your attitude to be 4 degrees nose-up to stay on the glideslope. For flare, pull up to 4+3 = 7 degrees nose-up.

Thats all there is to it! (Well, in theory... )

Jan

 

[Denco]

25 minutes ago, Litjan said:

If you come in on the ILS, your approach angle (the path the plane takes) is usually 3 degrees. So you must pull up BY 3 degrees to enter level flight - not TO 3 degrees. In other words, notice your attitude as you fly down the ILS (it might be anywhere from 0 to 5 degrees nose-up) and then ADD 3 degrees to it when you flare.

Example: During approach you determine your attitude to be 4 degrees nose-up to stay on the glideslope. For flare, pull up to 4+3 = 7 degrees nose-up.

Thats all there is to it! (Well, in theory... )

Jan

 

This is exactly what I've been doing. Sometimes it works sometimes it doesn't. I guess I must practice more. I really like the flight model of the 733. One tiny mistake on landing and it's going to be a bad one. Should the flare speed be vref or vref+5?

Edited February 19, 2017 by Denco

[Lucasvh]

To an extent I'd say that every landing is unique in its own way. Generally I flare as documented but due to turbulence, wind or just questionable flying by the pilot () my speed might be off, or my sinkrate increased very quickly, making me flare and idle the throttles at diffrent times than I generally would. 

You kind of need to "get a feel" of the aircraft, much like driving a car you know how it will react if you do X and Y.

I'm no pilot so I can't speak for the legitimacy of my actions, but hey it works!  

Edited February 19, 2017 by Lucasvh

[frumpy]

16 hours ago, Denco said:

 Should the flare speed be vref or vref+5?

Vref+5 is a common approach speed if there is no wind.

 

edited: As Jan says below, you need vref at touchdown, not over the threshold as I said.

However, the threshold should be right below you with the "50" callout (this way

you can tell whether you are high/low, and anticipate the effect on landing on

the right spot).

Edited February 20, 2017 by frumpy

[Denco]

I think I narrowed down what was causing the "anomalies". I did a few touch and go's with what Jan's said in mind. I flared with more force then I used too and it was better. Lesson learned is that one should not be afraid to flare with a bit of force. It has to be a quick and determined flare.

 

[Litjan]

There are a lot of aerodynamics and physics at play during those crucial last few seconds. The pitch change needs to be fast, and the plane will need a few moments to decrease the sink rate - so yes, we call it a "break" where you do a fast and deliberate input. A lot of factors will affect the trajectory of the plane, and very few landings are really alike. We aim to fly the approach with Vref+5 (and wind correction), bleeding the speed of to Vref at touchdown.

Its mostly a matter of repititve training at different conditions.

Jan

[cmbaviator]

Is it normal to feel a huge nose down torque when getting closer to the ground, I know that the ground effect will apply a negative torque, but it seems to be very abrupt even more when retarding the throttle, the pitch is decreasing pretty fast.

In the pmdg b744 v3, there is almost no negative torque when approaching ground effect, you even need to manually decrease the pitch below 200fts agl because of the huge increase of lift but no negative pitch torque felt. On the forum they said that normal but I'm surprised that the there is no negative torque applied on the queen when entering into ground effect. As I know that you had flown the b744, Jan, I'd like to have your input on the flaring of the b744 compared to the b733

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[Morten]

FSX/P3D ground effect is all wrong judging from what I've read about it. They have mixed up two different types off effect. Also be aware that we had reports of problems with ground effect in the latest XP11 bets's

[cmbaviator]

FSX/P3D ground effect is all wrong judging from what I've read about it. They have mixed up two different types off effect. Also be aware that we had reports of problems with ground effect in the latest XP11 bets's

I was talking about xp10. Ok xp11, its way too exagerated.

Id guess thzt pmdg woukd have tweaked the ground effect model in P3D

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[Morten]

Well, you said their 747 has "huge increase in lift", if thats the case they have not...

 

[Matheus]

I fly A320 on real life and the thing the most impressed me on the IXEG is the feeling that you actually landing a jet.

There are a lot of factors you must take account on your landings, things like your weight (heavier aircrafts are easier to land), the runway`s characteristics, the weather, etc. When you are flying an airliner, you must leave your ego at home, so a super smooth landing is in the end of the list of the things that you are aiming for. So always land on the touchdown zone, don`t scratch your tail on the runway, keep the G forces in the aircrafts limits and stop within the runway limits (with a good margin, please!!).

Back to your question: If you do always the same thing on a landing, the result will be always different! Try to feel how is your aircraft behaving and time your yoke and throtle inputs on that, after some landings you`ll be closer to your expactations, for sure!

[cmbaviator]

Well, you said their 747 has "huge increase in lift", if thats the case they have not...

 

The b747 enters in ground effect at 200fts, and you need to apply some forward pressure to maintain the path, some b747 pilots said thats realistic.

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[Morten]

5 hours ago, cmbaviator said:

The b747 enters in ground effect at 200fts

Not quite, there are atleast 4 types of ground effect that starts at different altitudes depending on wing design. The pitch down effect is just one of them.... so you need to know exactly which one of them you are talking about and the wing design.  There are a lot of misconceptions about "ground effect", also amongst experienced pilots.  

M