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Guest panda234

HANDS-OFF LANDING

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I was making an ILS approach to 08R at Gatwick (EGKK) in the stock C172 with the autopilot engaged and approach selected. I forgot to switch the autopilot off (distracted by the cat!) and the aircraft flared out and made a perfect landing - practically zero vertical speed at touch down.I flew it a few more times and noticed that just before touchdown the glide slope needle rose almost to the top just before the signal was lost. That must have been enough to cause a near perfect flare out.I guess this effect must be very dependent on aircraft type and the location if the ILS?Anyone noticed this elsewhere?

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Guest Charlie Hall

This is interesting. I have noticed a similar thing with an add on scenery for London Stansted (EGSS), though not whilst flying the ILS but by carefully slewing along the ILS path. I figured it was because the ILS was realigned to the slightly different runway position from stock. Is your airport and AfCad for EGKK the stock setup?

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My Gatwick's standard except that I've removed the VASI's from 08L/26R because the two runways are never used at the same time and only the one in use ever has lighting.

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I don't have an approach plate for Gatwick but I assume it is a standard Cat I ils?"ILS is classified by category in accordance with the capabilities of the ground equipment. Category I ILS provides guidance information down to a decision height (DH) of not less than 200 ft. What probably happened is your autopilot followed the glideslope to the 200 ft. decision height which is usually about 1/2 a mile or less from the runway-at that point you went "below" the glideslope-the autopilot tried to recapture by pitching the nose up while at the same time your airspeed bled off. By happy coincidence you ran out of airspeed over the runway and set down. Wouldn't suggest a regular practice of this though :-)http://mywebpages.comcast.net/geofa/pages/rxp-pilot.jpg

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Guest Charlie Hall

OK thanks. I'll go there later and try it myself.

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Gatwick ILS is Cat III though I'm not sure if FS recognises the differences.I'm sure it's just luck that it works.

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Guest av84fun

Actually, what you experienced is the limitation in FS9 software to model the entire landing phase and especially ground effect anywhere close to reality.I have raised this issue in other threads and don't want to be considered to be harping on it. A FEW aircraft will at least model a BOUNCE when the flair isn't executed properly...the RealAir Spitfire for example.But the vast majority of default and add-ons can simply be "flown on" the runway in essentially a nose down "glide slope" attitude at 400 fpm or so and result in a "chirp and stick" landing.When you noticed that in spite of your hands being off, "the aircraft flared out and made a perfect landing" what you saw was the faint hint of actual ground effect modeled in FS9 but that's not what would happen ITRW.ITRW, if you just drive it on nose down like that virually all except the lightest of aircraft (Cub drivers please chime in) your mementum will just drive right through the ground effect cushion...you will touchdown nose wheel first and either "wheelbarrow" and then quite likely crash or will slam the mains down and BOUNCE back up at which time PIO (pilot induced oscillations...i.e. using the exactly incorrect control inputs) will cause you to crash.Without getting all technical about it, ground effect results from the proximity of the wings to the runway causing a "cushion" of air that tends to create "float" until such time as airspeed bleeds off sufficiently to dissipate ground effect, at which point the aircraft can settle to the runway.Here is how ground effect behaves ITRW.1. Assuming a correct approach speed and deck angle and upon reaching a foot or two off the runway, the pilot must be cautious not to raise the nose too rapidly because if he/she does then the aircraft will "glance" off the ground cushion...which is called ballooning. The correct move is to fairly slowly increase the deck angle to no more the level and then wait for ground effect to dissipate...you can actually feel it in "the seat of your pants"...at which time AND ONLY THEN...is the nose very slowly raised to whatever the correct touchdown deck angle is in the machine you are flying. Many student pilots assume that the "flare" is one continuous movement and they will inevitably balloon for the reasons described above.2. If approach speed is too high, then one of two things will result. A) the better pilot will CAREFULLY raise the nose to no more than level and then just FLOAT.... AND FLOAT....AND FLOAT until ground effect dissipates or will execute a go around if sufficient runway is not available or B)the less skilled pilot will apply too much back pressure and the balloon ride will begin.The basic idea is not to think about "flaring" which is much too dramatic a word...but rather to first LEVEL OFF and then HOLD IT OFF...i.e. try NOT to land by slowly applying additional back pressure...which will cause the nose up deck angle or "flare" but the flare is the BYPRODUCT of correct landing technique...not the primary objective. Sometimes "round out" is used instead of flare but that is not correct either. The actual geometry is "flatten out" the "raise the nose" but the maneuver isn't "round" at all. In terms of the aircraft's trajectory, it is first FLAT and then angled slghtly DOWN in spite of the elevated nose.Flight models have advanced amazingly over the years and the better machines are really quite realistic now...except for the landing phase. Landing and airplane is just simply not as easy as most sim aircraft are modeled.So, even though incorrect technique will result in a lovely landing, better to do it correctly and hope that landing models become more realistic over time...although they may never because developers might quite correctly fear they would get too many complaints if their landing models were highly accurate.DISCLAIMER: I have not flown EVERY add-on model and I rarely fly jets so my comments are restricted to singles and twins up the King Air B200 category.ASEL/MEL/COMM/INST 1100 hours, time in most Cessna and Piper Singles, Mooney, C310/340 Navajo/B90 King Air

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Guest av84fun

EDIT to #1 above. You don't wait until you are 1-2 feet above the runway to START the level off move...maybe 15-20 ft. or so depending on the airplane. But you should be at a foot or two JUST AS you reach a level attitude.Regards,Jim

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Guest panda234

When you get close to the runway in rl there's an effect that makes you flare. It's the air that you're compressing under the aircraft and if your speed and attitude is right on you'll get a natural flare. My dad used to fly 104's, and he'd take someone up in a dual and just as they were landing he'd hold his hands over his head and say "look, no hands." Guaranteed to freak out the guy in the back seat. billg

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>When you get close to the runway in rl there's an effect that>makes you flare. It's the air that you're compressing under>the aircraft and if your speed and attitude is right on you'll>get a natural flare. My dad used to fly 104's, and he'd take>someone up in a dual and just as they were landing he'd hold>his hands over his head and say "look, no hands." Guaranteed>to freak out the guy in the back seat. >ROTFL :D I would never imagine F104 with his little wings (span and chord) and high wing loading, had a so significant ground-effect induced flare.

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> Sometimes>"round out" is used instead of flare but that is not correct>either. The actual geometry is "flatten out" the "raise the>nose" but the maneuver isn't "round" at all. In terms of the>aircraft's trajectory, it is first FLAT and then angled>slghtly DOWN in spite of the elevated nose.>I've seen different uses of the term "roundout". Although some call the flare the same as roundout, I've always called it the transition from a nose down attitude, to leveling out about 20' off the runway. Then as airspeed bleeds off, we flare a foot or so off the runway while making it a point to keep the nosewheel dropping last. Of course, all aircraft don't approach in a nose down attitude.>>DISCLAIMER: I have not flown EVERY add-on model and I rarely>fly jets so my comments are restricted to singles and twins up>the King Air B200 category.>The following is an excellent "jet" tutorial that didn't appear to make it over here. At least I havn't seen it here. But it's well worth reading, especially about landing jets with small wing surfaces & high wing loading.http://forums.flightsim.com/dcforum/DCForumID21/21707.htmlL.Adamson

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Guest panda234

murmur, there's not really a significant ground-effect induced flare in a 104. You basically fly it in, but there's enough of one, and enough ground effect, that if you do right you can do it hands off. billg

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Guest panda234

check out http://www.starfighters.nl, then click Starfighter Videos, then Riat Cottesmore landing. The first guy does a nice flare, kind of greases it. The second guy bounces, but hey....billg

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In my experience much of the 'float' one experiences during the flare has as much to do with approach speed as any 'ground' effect. On final approach in my Cessna 206 I use about 70 knots if I'm light, and 75 if I'm on the heavy side. I carry about 18 inchs of manifold pressure all the way to the threshold, and generally 35-40 degrees of flaps. The nosedown attitude is fairly pronounced because of the very large flaps, so the transition to 'flare' is significant. The 206 will not float if the airspeed is managed correctly.On the other end of the spectrum I also fly a Cessna 120. The 120 has no flaps, which results in a near level approach attitude at an approach speed of about 60 knots. If you need to increase the rate of sink, you pitch the nose up just a little (as long as you continue to manage the power and airspeed obviously). You can actually approach, with a little power, at or near the three-point touchdown attitude. Since I have no landing lights on the 120, I use this technique for night landings. Arresting the rate of descent at touchdown by adding a touch of power, usually results in a near greaser, again with no tendency to float at all. Having said that, though, if you mismanage the airspeed and attitude down final, you will fly into the next county when you begin the 'roundout'.However, to avoid confusion with respect to what I've just said, there is a transition phase from the initiation of the flare (when the angle of attach is increased) to touchdown, as the stored energy dissipates. I wouldn't refer to this as 'floating' though. Just my two cents,Leon

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>In my experience much of the 'float' one experiences during>the flare has as much to do with approach speed as any>'ground' effect. I agree. As far as I'm concerned, it's still lift from a too high approach speed. What I don't feel, is some big cushion effect, that some might expect by reading about it.But, I don't really feel much of anything. With a heavy wing loaded small airplane, you can even get the feeling that the floor is about to fall to the ground; and it can, if you don't watch it! :DL.Adamson

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>But, I don't really feel much of anything. With a heavy wing>loaded small airplane, you can even get the feeling that the>floor is about to fall to the ground; and it can, if you don't>watch it! :DI'm with you on that one. That sudden departure from what was, just a split-second ago, a perfect set-up for a great touchdown, will sure get your attention. You may only be a foot or two off the ground when the bottom falls out, but it will still cause a red face and a load of excuses to your passengers :-lol .Leon

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Guest panda234

yes, the sudden departure from what was to what is will always get your attention. That's why we do it. You have to check out the video link I posted above, not much of a flare at all, just fly it in. And yes, blood pressure goes up, heart beat goes up, that's why we do it, hehe. As an aside, the apollo astronauts had all kinds of instruments on them, checking out heart beat etc., and I forget which one, but one pilot didn't raise at all as it lifted off, and didn't raise either when he did the re-entry thingy where you either bounce up or burn if you don't do it right. I can be calm if I have to be, but jeeze, my heart would be beating fast. His didn't, his was like he was peeing in the morning. billg

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Guest av84fun

<>But approach speed is one of the factors in the ground effect equation. It is called the "ram effect." For example, there is no ground effect when you are taxiing but lots of pilots, who overload their aircraft or operated at excessive density altitudes, come to grief when the airplane "takes off" but then can't climb because it is the SPEED INDUCED ground effect that caused them to leave the runway...without which, the airplane won't fly and ends up in the weeds.<>Neither will any other aircraft...to any appreciable extent.<>Roger that...but not in the vast majority of FS9 aircraft...in fact, you don't get any appreciable float AT ALL, nor...again in "most not all" aircraft, you don't even bounce if you drive it onto the runway at 400 fpm and at an excessive airspeed. As you know, that IS NOT the way it works ITRW.<>Right, so long...as you stated in your post...that the approach is managed properly with respect to airspeed and deck angle. But my point is that even if you MISmanaged in the sim aircraft (most but not all) you get a "pro landing" anyway.Below is an excellent link for those interested in ground effect.Regards,Jim http://www.se-technology.com/wig/html/main...pen=aero&code=0

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Guest av84fun

<>With respect,L.Adamson, I think you are missing the point.If you are conducting a stablized approach and transition from a nose down deck angle to a level deck angle at, say, 1000 agl then, if you apply only sufficient back pressure to achieve the transition to level then what you will do is simply level out.But under the exact same conditions, if you apply the exact same back pressure within a wingspan of the ground you will balloon upward due to well documented aerodynamic laws.No, it's not felt DRAMATICALLY like bouncing on a trampoline and in fact, ground effect is mostly FELT when when is DISSIPATES and OBSERVED (by ballooning) when it initiates.In landing, ground effect is one of your best friends if the approach is managed properly because that slight but VERY noticeable sinking feeling you get in your butt is what signals that it is time to slightly but steadily increase the back pressure and that you can then do so without inducing an upward balloon. If you continue to raise the nose to touchdown attitude before that sinking feeling (whether you feel it or not...it is there) then you will balloon.The old time flyers weren't kidding when they said they "fly by the seat of their pants." The dissipation of ground effect is one of the things they were taling about.:D>>I may be misunderstanding you but those two sentences seem to be in conflict...except if you are differentiating between heavy and light wing loaded small airplanes...but the aerodynamic effects of ground effect are present in ANY aircraft...just to different degrees...but those without heaviliy calloused buttockses will feel it if they tune in.(:Regards,Jim

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Guest panda234

my bad, sorry, check this out...http://www.starfighters.nl/then do 104 videos and then Riat_Cottesmore_landing_2_F104S_ASAM_2000 for the video. My bad, argh...EDIT: it's starfighter videos...billg

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>in "most not all" aircraft, you don't even bounce if you drive>it onto the runway at 400 fpm and at an excessive airspeed. As>you know, that IS NOT the way it works ITRW.>For non-pilots like me, in this case do you mean bouncing after touching ground with gear, or bouncing solely due to ground effect, without touching at all?

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Guest panda234

If you saw the bounce, it wasn't very much of one. A little fast, a little low, and stuff happens. If you were the first guy down, you could have taken your hands off. billg

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Following up the points made in this thread, I repeated the flight but turned off the autopilot at 100 ft. There was a slight reduction in the rate of descent (not nearly as much as with the autopilot on) and the result was a heavy landing with a bounce. This suggests that most of the effect is due to the autopilot.The glide slope transmitter is modelled as being offset from the centre of the runway to reflect real-life: you can't have a transmitter sitting on the touchdown area for obvious reasons. This means that the distance from the aircraft to the glide slope transmitter can never be zero - its minimum value is the offset.IF FS calculates a target height based on the actual distance of the aircraft from the transmitter, THEN the target height will become too high as the aircraft approaches touchdown and the aircraft will appear to be below the glide slope. For example, when the aircraft is on the ground alongside the transmitter it could appear to be 3 deg and 7m below the glide slope assuming a 3 deg glide slope and a 150m offset. These values are based on ground level and they would be reduced by whatever height FS assumes for the aircraft relative to the bottom of its tyres. The transmitter offset for 08R at Gatwick (EGKK) scales at about 150m from the aerodrome chart.

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Guest panda234

wow, you're way too smart for me. I think you know what you're talking about, but I'll have to give you credit, I just don't know. The flare? Did you see the video? That was a flare, well, he greased it so well he didn't need to flare, really. But he did. Too bad nobody flies them anymore....billg

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To Jim (or indeed anyone)As a matter of interest, what do you think of the Flight1 C172R's landing behaviour? It seems quite good to me, but then I've never flown one in real life (and I can't remember much about my three landings in a Piper Warrior..)ThanksIan

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