Landing on undulating runways [Archive]

FlyingForFun

7th May 2003, 22:52

I'd be interested to hear from anyone who regularly flies into a field with an undulating runway. I suppose I'm talking about anything from an Elstree-style runway (the initial dip on 26 followed by the upward hill) through to private strips on ground which is not flat. I'm not talking about a constant up-slope or down-slope, nor about bumpy runways, both of which I can handle - I'm specifically interested in fields with several rises and falls over the course of the runway.

The reason I ask is because I visited Elstree for the first time last weekend, and found it extremely tricky. I made two landings there, both pretty much identical. Because it was a bumpy day, I was keeping my speed up a little bit. I started off by being high over the trees on final to 26. This made it difficult to get the speed back. I rounded out over the numbers, but then floated a short way down the runway due to my excessive speed. And that's where it went wrong. What happened, I think, is that I maintained a constant height relative to the far end of the runway (where my attention was focused). As I drifted down the runway, I reached the start of the up-slope part of the runway, and the ground rose to meet the aircraft. This resulted in a main-wheel first landing, something which every tail-dragger pilot knows is a bad thing (unless a wheel-landing was intended of course).

So any advice from pilots who handle this kind of thing regularly would be appreciated. Where exactly do you focus your attention in order to ensure that you remain at the correct height above the bit of runway you're currently overhead through the flare? Any Elstree pilots care to comment? And I'm sure there are many fields which are far more tricky in this respect!

Thanks!

FFF
-------------

Tall_guy_in_a_152

7th May 2003, 23:29

I had a similar experience on my one and only Elstree landing. I had attributed my high approach to 26 to the unusual aspect ratio of the runway (relatively wide) which (now that you mention it) is compounded visually by the up-slope at the western end.

As FFF says, I'm sure there are many more extreme examples of both these runway 'features', but in my limited experience Elstree is the worst.

TG

BlueRobin

7th May 2003, 23:39

Crest and dips are a problem that befalls the commercial guys too. E.g. original runway at Manchester has a big rise about 1/2 way along.

Hmmm...for a Europa to have a problem, the frequency of peaks must be high given the a/c's short landing distance?

My theory - armchair advice this Mr D... Your problem started with the protracted float, so keep the speed down to minimise it. Land on a uphill part with this short-field landing config. Make sure you don't have too much float/lift under wings as this will mean the subsequent crest acts as a ski-jump.

M14P

8th May 2003, 00:06

I absolutely buried my work-plane at Helsinki the other day - Rwy 15 has a Manchester-style bump in it. Everyone knows about it - the best I could come up with (having made a few excuses in the breifing for the ensuing thumper) was to say "Here it comes...!" about three-quarters of a second before impact.

Humfff!

pulse1

8th May 2003, 00:08

FFF,

I am so glad that you asked this question because I suspect that many of us have this problem. I certainly do and it is compounded by the combination of turbulence (high approach speed) and obstacles requiring a steeper than usual approach.

In my case, this causes a more sudden transition between looking at the flare point and then at the end of the runway.

In my gliding days, at Dunstable, we were taught to follow the ground but you cannot do this by looking at the end of the runway. It's a lot easier in a glider too. We used to laugh at the many aborted attempts of GA pilots trying to cope with the severe changes of slope.

I hope that we can get some good advice here.

QNH 1013

8th May 2003, 00:31

Undulating Runways: For practice try:

Eggesford in Devon

Nayland in Essex? (very different)

Fishburn in County Durham

They are all grass, and Nayland feels like landing on the side of a house roof.

drauk

8th May 2003, 01:45

FFF, something to think about is the discussion that has gone on here before about where to look to judge the round-out/flare.

You no doubt remember the postings of Chuck Ellsworth on this subject. Actually, in a more recent thread I recall you summarising the early postings he had made, where you discussed the fact that the different parts of the approach had different names and that was the cause of some of the confusion (I can't find that thread right now unfortunately). However, I think you actually misquoted him in that you said once you agreed that you were talking about having reached the flare point you transition your viewpoint to the end of the runway. (As this is from memory I apologise if I've misrepresented the posting you made) He actually said that was absolutely the wrong thing to do. And with Elstree's upsloping runway the problem is even more marked. Instead he recommends about 500' in front of you, if you're landing at around 50-70knts.

All my flying has been at Elstree and I'm not sure precisely where I focus when I'm landing, but on neither runway is it the far end. Solving your problem isn't made any easier by the fact that you can't fly circuits at Elstree, unless you do so with a resident instructor (and then only one from Cabair or Firecrest).

QDMQDMQDM

8th May 2003, 03:07

I don't think there's a magic formula -- just do it a lot, get the speed right and touch down where you planned to touch down. If you don't touch down at the right place on an undulating runway you can get into trouble -- too much float, downsloping etc. -- so it's more important to fly accurately than on 7000 feet of tarmac.

It's down to practice, like everything else.

QDM

Wycombe

8th May 2003, 05:27

Have only landed there once, but found that the westerly runway at Kemble has a bit of a strange perspective. The undershoot is in a dip and I found that the threshold came up to meet me, resulting in an arrival a few seconds earlier than anticipated!

Anyone else found this?

Bluebeard2

8th May 2003, 07:34

I used to fly quite a lot from Elstree, so I was used to the humpy runway. Can't say 26 ever presented too much of a problem, although I did used to always aim for the start of the pan for a round out just prior to the threshold - in a C152/C150 this would normally get you on at the numbers and would give you a fighting chance of a turnoff at alpha (the first taxiway on the left after the numbers) without excessive braking or a huge backtrack.

Funnily enough, it was the rarely used 08 which used to give me the willies. Apart from the 2deg downslope (plus trees at the end), the undershoot and threshold were flat, which did make judging the angle of descent very tricky. Just to add to one's woes, there would be a downdraft off the trees if there was a southerly wind, which would handily take 50ft off you. Nice.

FlyingForFun

8th May 2003, 16:48

Wow - seems like this is causing lots of people problems. Strange that I've never seen it discussed before!

Drauk, you're memory of what Chuck and I said is pretty much correct. I seem to recall that one of us (I think it was me) suggested that the common advice to "look at the end of the runway" was given because it is usually a good approximation to the correct place to look, but Chuck did give a formula or a guideline which was dependant on your speed. But I'm not sure that helps in this case... even if you concentrate on a point which is the correct distance in front of you, if the runway is moving up and down beneath you you won't have the visual references to be able to compensate for it.

Predictably, the Elstree fliers such as Drauk don't say that they have problems. So I'm sure there is a solution, which all the Elstree pilots instinctively know without even realising they know it.

Is there anyone who trained or who has done lots of flying at somewhere with a flatter runway, then moved to somewhere like Elstree? How did you find it when you first moved there? Have you learnt to deal with it since you've been there? Do you know what you did to learn to deal with it?

QNH, thanks for the suggestions of other places to go. Do you know if any of them offer free landing fees off of circuits? ;)

FFF
--------------

QDMQDMQDM

8th May 2003, 17:27

No landing fees at all at Eggesford -- circuit to your heart's content on a VERY undulating runway. ;)

QDM

Dude~

8th May 2003, 18:11

I used to fly from Popham and have recently started flying from Elstree. I think the key thing is to be consistant. Make sure your approach is stable, on speed, none of this 'extra 5kts for saftey' and a reasonable height, rate of descent and power/flap setting.

Airline pilots 'fly the numbers' and it works for them. If you arrive over the threshold at the right speed it gives a much better chance to land well, than if you arrive over the threshold off centre/ too high / too fast.

Of course, a stable, precise approach will not directly help on an undulating runway. Here you need to be prepared for whats going to hapopen. You need to think about the slope of the landing zone, and prepare mentally. It doesnt matter if you level off then let the runway rise to meet you rather than you sinking to meet the runway. Just so long as the speed is correct. At Popham, I tended to 'round out' (not flare yet) in a shallow bank to align with the runway, then power completely off and a gentle flare since the runway continues its downslope for a while. Here, a normal flare (ie maintaining height at the expense of airpseed) would leave you gaining height over the runway. THe opposite happens at Elstree on 26 where you need to flare and almost enter a very slight climb to prevent impacting the runway with too high a rate of descent. This is exasperated by aircraft with high Vat speeds. What this means is that your airspeed is going to decay very quickly so a little power may be helpfull, but then of course, at Elstree there is not much room to play with.

I once spent a whole summer at a grass strip with no obstacles and 900m practising presicion landings, and high rate of descent / high drag / power off flares. You have to be precise, otherwise you end up stalling at 4 or 5 feet.

Anyway, I have dribbled on enough. Think about the anatomy of your landings and go over it again and again then it will flow better when you come to fly. A relaxed mind will perform much better than a mind struggling to keep ahead of the aircraft!

:cool:

Tinstaafl

8th May 2003, 19:48

I have to operate into these sorts of runways so on reflection I think this is how I do it...

There seems to be a some competing requirements in the situation:

1. Some reference for pitch attitude control ie the end of the runway or some point along it far enough away to remove the perception of rate of longitudinal closure

2. Some reference to determine rate of vertical closure ie sink (or the opposite.... :O )

3. Some reference that might allow you to anticipate #2.

I think that with a flat (note: not necessarily level) runway then looking some distance down the runway can accommodate all those tasks. As soon as the runway becomes undulating, crested or dipped then that single reference point becomes inadequate.

1. Pitch reference: I use some length down the runway OR the end of the runway if it's short OR the visible horizon if it's crested.

This gives me an attitude reference point that is relatively constant. If crested then as I lose the crest I transfer to using further along the runway.

2. Sink rate: I tend to look much closer. Not very far in front of the cowling (10m? 20m? 50m? Not sure, but it's quite close). I also pay more attention to my peripheral vision.

Using the perceived sink rate I modify my 'normal' flare & hold off, pitching a bit faster if I'm sinking fast, less so if I'm not sinking enough. The goal is to approx. fly parallel to the surface regardless of its slope then achieve a controlled sink.

This is a very short term 'reaction' type input.

3. Anticipation: If I can see the runway is falling away/going to fall away then I plan not to hold off as much, allowing the a/c to descend. Similarly, if I can see the runway rising ahead of me then I pitch more with the aim of flying parallel to the surface (not the horizontal).

This is a slightly longer term modifier to #2 above.

The end result is that I scan ahead & back throughout the process.

Additionally I modify my power usage. If a downslope is the first 'problem' then I'll reduce power earlier &/or faster. If an upslope I'll reduce power later &/or more slowly. If quite a steep up slope initially I'll sometimes fly a quite shallow approach gradient (obstacles permitting of course) to reduce the amount of flight path change needed.

Another 1 or 2 kts above 1.3 Vs can be useful to give a **little** extra energy for the extra pitch up for the upslope. I don't mean 10 kts or whatever, but just the aiming for the fast side of the required speed instead of the slow side.

redsnail

9th May 2003, 05:13

FFF,
Good question. I've operated on some fairly entertaining strips in my time. Consistancy and practice are the key.
As you know, a good landing follows from a good approach.
So, a nice stabilised approach is the key. Get the numbers right will help the landing enormously.
Go to the aircraft manual and see what they say for the approach speed. For fun, calculate out the 1.3Vs speed too. This will hopefully convince you that you don't need to add extra speed for your approach. (ie you are well above the stall already). As you've found out, the extra speed becomes a liability when landing. ie the float etc.
I rarely add anything more to the Vref speed other than what our ops manual says we can. Reason? No performance data on "extra" additives.
So, we've hopefully got the mechanics of flying the approach sorted. Now, what about the strange and sometimes confusing visual cues? (The beauty of PAPI and VASI). It does come easier with practice but pick a point on the runway and fly to it. Shift the eyes away from the point when you can't see it. Try not to be rough or jerky at this point. The aeroplane will do what you ask.
The objective is to land where you want it to. Not where it thinks it should.
Nailing a good landing (and approach) into a tricky aerodrome feels great.
Don't fall into the trap of being "spooked" by the conditions. Stay on top of the aeroplane and use the published speeds and techniques.

gasax

9th May 2003, 15:59

I routinely fly onto a strip which has steep slopes and intermediate bumps. A lot of what is posted above is not very helpful.

Too many baby airline pilots - PAPIS on a runway that really undulates????? Get real the diference in level here is certainly visible but it is not big enough to be an excuse for a poor landing - all of the variation will be within the ground effect zone, so if the aircraft is pitched up enough to keep the nosewheel clear you will see/feel very little difference.

Some of the other posters have the guist of it - looking at the end of my strip is not possible - it is out of sight! What is very important is looking at the touchdown point and making sure that the aircraft is pitched up sufficiently to ensure landing mainwheels first. The second action is to land using power. Most of the time I arrive with a fair level of sink, that added pitch increases the effect, the only way to land now is to apply power to control your height above the landing point.

This usually means increasing to power to 25% of so in the roundout to check the sink and then landing at idle. It does need a bit of practice but it is straightforward.

Landing without power requires extra speed, because of the added drag during the flare, and it makes the whole process less forgiving.

But as far as undulations are concerned, on the down part simply hold the attitude and do not let the sink rate build. If you attempt to alter the attitude of the aircraft to match the downslope disaster lurks there. The throttle is the answer.

Dude~

9th May 2003, 16:20

Gasax,

I don't like your comment about too many baby airline pilots. You cannot diss flying the numbers. High speed approaches are the cause of numerous nose gear collapses amongst inexoerienced pilots.

You also say, 'What is very important is looking at the touchdown point', well only up to a point, but then this has beaten beaten to death before so we shant go into that here.

As for power, I think thats absolute bull. There is no need for power in the round out in light singles, maybe in a heavy single or light twin when rate of descent is high. Power will simply increase the landing run. It is perfectly possible to round out and flare without power, it simply has to be acurate because the aircraft will decelarate more quickly than with some power. Power will do nothing to help Flying For Fun's landings.

Just my oppinion and experience of course!

QDMQDMQDM

9th May 2003, 16:27

Power will simply increase the landing run.

No. Low speed, full flap, fistful of power, back of the drag curve, chop the power, plonk down exactly where you want and stop.

QDM

FlyingForFun

9th May 2003, 16:30

Tinstaafl - thanks, that was exactly the answer I was looking for! I think I will try to practice looking closer to the aircraft for sink rate clues before going somewhere like Eggesford to practice.

Everyone else, keep the advice coming, it all helps. Might be worth re-emphasising that I'm flying a tail-dragger, so keeping the attitude high enough to land main-wheels first isn't enough, I have one very specific attitude in which I must land. Nose-low and I bounce, nose-high and it'll stay on the ground but may not stay in one piece if I do that too often.

There is a theme, which Reddo has emphasised, about not adding an extra few knots. This sounds like a very valid point. On the day in question it was pretty gusty. I have a Vs0 of 42kts, and I usually use Va of 55kts. Flapless landings are not an option since the gear and flaps are on the same lever. Because of the gusts, I was approaching at 60kts - the gusts were reducing the IAS to below 50kts at times. Maybe I would be better sticking to airfields I know, or staying on the ground, in these conditions in future - at least until I'm more capable of handling these undulations.

FFF
------------

Dude~

9th May 2003, 17:24

I agree entirely QDM, but Gasax didnt mention the low speed, full flap back of drag curve thing.

Aerobatic Flyer

9th May 2003, 19:28

I do most of my flying from strips that are sloping / undulating. There are several factors to take into account.

First, preparation. Know what the slope / undulations are before you arrive. As a general rule, if you can see the slope from the air, it is quite steep. The undulations will probably therefore only become apparent when you're low, and you may not be in a position to land on the most favourable part of the strip.

Second, precision. This has been stressed by several people above. You need to choose your touchdown point, and make sure you touch down on it.:) The best way to do this is to pick an aiming point a suitable distance before your touchdown point (the distance depends on the wind, the aircraft type, the slope, and the speed at which you have decided to fly the approach), and fly a constant-speed approach to that aiming point. You don't need low-speed back-of-the-drag-curve heroics. If the strip is short as well as undulating, you just move your aiming point a suitable distance before the strip to ensure you touch down right at the start.

Third, the flare. Chuck Ellsworth detailed this far better than I can recently. As gasax says, on an undulating / sloping strip there's no point in looking at the end of the strip, 'cos you often can't see it. An important point about the flare on a sloping strip is that it should be initiated at the normal height above your touchdown point. This could mean that you are much higher than normal above the ground when you initiate the flare. You have to resist the urge to fly down to the normal height then pull up sharply to flare, or you will likely stall. It takes a bit of practice to get used to it, but is not a big deal.

Fourth, speed. The rule of thumb I use is as follows: normal approach speed for any slope up to 10%. Add 1km/h (one day the French will use knots for light aircraft... :rolleyes: ) per additional % of slope after that. So for a 20% slope, my approach is 10km/h (about 5 knots) faster than usual.

Fifth, power. Landing on a sloping strip, gasax's advice is spot on. If you cut the power to idle as you start the flare, and then have to pitch up significantly to get a 3-point attitude above the slope, your speed will fall very quickly and you will probably have a very abrupt arrival some way short of your intended touchdown point. If instead, you leave a bit of power on during the flare you can reach the 3-point attitude (do you say 2-point in a Europa :confused: )just above the touchdown point. Cut the power and you're down.

As a final comment, if you are able to choose your touchdown point I find it's generally preferable to land in the slope on an undulating runway. If you land in a "concave" section where the slope starts, the flare is more difficult - your pitch attitude needs to be continuously increasing to follow the slope. Landing in a "convex" section is harder still (but very satisfying if you get it right:cool: ). After the flare you need to relax the back pressure and follow the ground as the slope levels off. If you don't, you stall in from several feet up.... :uhoh:

Penguina

9th May 2003, 20:24

I am a novice, but trained at Elstree.

Landed on 26 for the first time in 8 months yesterday and there was a little balloon-ette. Thinking about it, and your post, I think there is a greater tendency to do this on 26 and to land flat on 08. It's tempting to overreact to the slope.

Also, I was told to look at the end of the runway when I learned, and found it didn't help at all. Maybe I've developed a technique where I look ahead, but ignore the slope (if successful)?

I don't understand why you need to come in faster for a runway with a 'surge' - can someone explain? (But then I've missed a bit of this thread I think and have to come back from lunch now... :rolleyes: ) I find wherever I'm landing it's easier if my airspeed is on the lower side towards the end. Surely that's universal? Power sometimes helps me control sink rate too, again, dunno if this has anything to do with undulating runways or not.

gasax

9th May 2003, 22:06

Nice try Dude - but wrong. My objection to baby airline pilots is light aircraft pilots who fly approaches at 3 degrees using PAPIS and the like. This is not the way to operate light aircraft.

As for adding extra speed I only stated that for power off approaches to steep slopes - do try to keep up!

Anyone flying a 3 degree approach is likely in a nosedragger to bounce or wheel barrow on an undulating runway. The aircraft simply has too much energy (speed!) to stop flying. Try that in a taildragger and you will get a huge balloon. To achieve a genuine holdoff in ground effect you will not be flying a Vs +30% - there is every likelihood you will be around Vs.

If you fly a steeper approach, or you achieve a genuine holdoff rather than just 'flying onto the ground' you are flying on 'the back of the drag curve' - whether you like to think about it as that or not. The genuine hold off however consumes a lot of runway, because the 3 degree approach gives you such a speed margin to start with. You are perfectly correct that adding power from that sort of aproach just increases the length of runway - it does - but if you are flying over a large concave area that is exactly what you need - otherwise the sink rate will push the wheels up through the wing/fuselage/whatever.

In the flare (a proper flare that is), the aircraft has much less power than it needs, the speed is decaying rapidly, landing is imminent, if not beaten by a stall. Now all this happens very close to the ground so you don't stall - but many do sink very rapidly!

Aerobatic has filled in the details nicely.

The summary is that adding speed on uneven surfaces adds complication and danger, fly the attitude use the engine and control your landing point.

Sorry for ranting, but landing fast is actually an oxymoron.

Monocock

10th May 2003, 00:27

Pardon me for my agricultural attitude to all this but for what it's worth heres my sixpenneth........

Questions I ask when going into an unfamiliar farm-strip. (I have yet to land at a tarmac strip that requires any massively different handling technique to normal, even the ones that do look lumpy like Elstree etc)

1. Are the bumps coming straight at you or are they slanted across the r/way? This does make a huge difference in terms of what to expect in the event of a balloon or even once you are rolling to a stop.

2. Are you landing into a x-wind where a ballooning episode could send things fruit shaped el-pronto?

3. What is the landing speed of the a/c? A Thruster is hardly going to be as affected by a lump at 30 kts as, say, a fast and floaty 182 with no passengers.

4. Is the last 150 m UPhill or DOWNhill. I recall landing away from the buildings at Eggesford once on a warm balmy day with no wind........anyone who knows it will understand what I mean.
:ooh: :ooh:

I do feel that if you try and judge the peaks and troughs then it is bound not to help really, the key is putting it down where you want it (normally about 30 yds behind where it ends up!!!)

Being too transfixed on the bumps only drags attention away from the rest of the job at hand such as flaring, keeping straight and watching the end of the runway coming at you.

I'll never forget going into Westbury-Sub-Mendip a couple of years ago and being so transfixed by the fact that the runway was curved that I almost forgot where I was aiming for, the plane gobbled up the runway faster than I would have liked.

The moments between travelling downhill and uphill always seem to slow the a/c down beautifully. I have always felt this is due to the "compression" factor in the u/c that takes out some of the momentum. You can feel it through the seat and this is the point I would normally apply the brake (if needed). Braking downhill (unless really necessary) never really seems that effective.

All the above relates only to particularly lumpy grass strips, perhaps not exactly where this thread was coming from originally?

IMHO I would say that taking off on strips such as those I am describing takes as much (if not more) concentration than landing.

QDMQDMQDM

10th May 2003, 00:43

Is the last 150 m UPhill or DOWNhill. I recall landing away from the buildings at Eggesford once on a warm balmy day with no wind........anyone who knows it will understand what I mean.

On a day like that, if you don't touch down here in the Easterly direction BEFORE the first hump you're in trouble, or rather you're not, as long as you go around straight away.

Watched several go-arounds the other day by someone in a high performance aircraft, clearly spooked by poor visibility and rain, coming in hot and high, touching down after the hump and thankfully deciding not to brake downhill on wet grass.

On the other hand, touch down before the first hump and you have to put on lots of power to taxy up it. Undulating fields can work for or against you.

QDM

Monocock

10th May 2003, 02:52

QDM, how's things in sunny Devon? Haven't been down to Eggeford for a year now but would like to call in one day soon.

Am I right in thinking that you lucky chaps who are based there must have some fantastic afternoons watching the antics that go on with first timers at that weird and wonderful strip? I can picture it now; barby smoking, beers flowing and........hey look lads here comes another one.........wahaaaaaayyyyyyyyyy!!!

Saying that, I find the flight down to you more stressful than a night in with the mother-in-law knowing my humble efforts at landing are going to be witnessed !!!!

Will drop in soon as have a friend at N. Tawton who I havent seen for over 12 months.

QDMQDMQDM

10th May 2003, 05:40

Will drop in soon as have a friend at N. Tawton who I havent seen for over 12 months.

You've even got a new one-way strip at North Tawton now:

http://www.devonstrut.co.uk/tawmill.htm

Head south with the cheese factory on your left and you're on final. The owner is a gem and the strip is very good, although the grass is too long for the next week or so until he has silaged.

Saying that, I find the flight down to you more stressful than a night in with the mother-in-law knowing my humble efforts at landing are going to be witnessed !!!!

Most people here are pretty charitable and actually very few come in who aren't up to it -- they just take a look and go elsewhere, not that it's really very difficult. Now, how about doing it at night...?! ;)

See you soon. We're having a number of fly-ins over the summer and they're usually well-attended.

QDM

Oktas8

12th May 2003, 06:54

This topic is very interesting, and I wonder if someone could answer a q I have about undulating strip landings?

Is it common practice to retract flap in the flare to allow the aircraft to settle to the ground more quickly if for some reason the aircraft floats further than expected (ie due wind gust etc)?

thanks,
O8

redsnail

12th May 2003, 13:13

Never heard of that technique. Wouldn't really want to try it either. If trying to make it "stick" last thing I would consider doing is retracting the flaps. My reasoning, the last stage of flaps are the "draggiest". I don't want to reduce the drag (any more than ground effect already has).

Any way, knowing my luck I'd retract the gear and not the flaps. Still, it would be a ripper of a short field landing. :D

mad_jock

12th May 2003, 20:06

I have never heard of dumping the flap in the flare.

At low speed you would drop like a brick with the nose dropping.

I have been taught though to dump flap after all the wheels on the deck to to stop gusts getting you up again, and to give the wheels more grip. Manual lever flaps lend themselves to this but electric take a bit more time.

If you want undulating runway try Barra it changes every time the tide comes in. Landing wasn't to bad just drop it on the top of a rise. Takeoff the sand sucks you down so when you do unstick you feel as if you leap into the air.

MJ

FlyingForFun

12th May 2003, 20:15

I've also heard of dumping the flaps only after you're firmly on the ground. Less lift means more weight on the tyres which makes the brakes more effective so you stop quicker, or so the theory goes. Can't say I've ever tried it though. And when the flaps and gear are on the same lever, as they are in my 'plane, it's not an option at all :eek: :D

I can see how, in theory, it may help with a short field landing, but I can't see how it's going to help with dips and crests, though?

FFF
-------------

gasax

12th May 2003, 23:04

It's never a dull moment here is it? People who cannot land on something not perfectly flat and now interesting 'advanced techniques'

I've heard of it but to be blunt think it's rubbish. The time period where flaps will give you enough lift to soar skyward after you have touched down is extremely short (so long of course as you didn't fly onto the runway at 1.3 x Vs!!!).

Of course there is the small matter of not retracting the gear inadvertantly, or seeing out of the windscreen to reach the flap lever, whilst you are still travelling quite fast.

Try actually holding the nose wheel off and the flaps will act as very effective airbrakes. On my Terrier (a taildragger) they are more effective than any brakes when in the full position.

Landing at the lowest sensible speed is going to be a far better bet than trying to stop 'lift' to enable better braking etc..

mad_jock

13th May 2003, 00:17

I agree gasax.

I was trying to figure out what O8 was meaning.

MJ

Oktas8

18th May 2003, 09:52

Thanks for the replies everyone - I appreciate your time.

To clarify, I was not referring to the practice of retracting flap when already on the ground, but retracting flap in the air in order to get on the ground earlier. Not that it makes much difference if you use the gear lever by mistake!

Zlin526

19th May 2003, 03:40

Somebody mentioned Nayland......

It's actually in Suffolk, and is remarkably free from undulations, just a steadily increasing upslope until you reach the crest of the hill, where it flattens out for about 150m. Wonderful strip, not for the faint hearted PPL fresh from GFT....

Normal take off is downhill, landings uphill no matter what the windspeed/direction is, but I have launched a Cub into wind from the 150m flat bit at the top.

I've spent the past 10 years trying to work out how a pilot (believed to be 'an instructor'), in a 150hp Super Cub (almost the world's best STOL aeroplane), managed to leave the aircraft in rather a mess in the upwind hedge????

Zlin

QDMQDMQDM

19th May 2003, 04:56

I've spent the past 10 years trying to work out how a pilot (believed to be 'an instructor'), in a 150hp Super Cub (almost the world's best STOL aeroplane), managed to leave the aircraft in rather a mess in the upwind hedge????

That deserves some kind of aviation achievement award. A little under gross, with a little wind down the runway, a 150Hp Super Cub is off in under 50 yards.

Interestingly, even though (perhaps because) it is such a benign low speed aircraft, many cub pilots die by stall / spin accidents. The chapter by Leighton Collins at the end of 'Stick and Rudder' gives a brilliant and chilling explanation of how such events come about. It should be compulsory reading and has certainly scared me off steep turns at low level (not that I needed much scaring).

David

QNH 1013

19th May 2003, 07:28

Zlin526, Thanks for correcting my rather poor geography - thats why I put the question mark in after Essex. Hope I've not insulted anyone in either county!
Your description of Nayland is spot-on but I should point-out to anyone who hasn't been there that the "upslope" at Nayland is the steepest I know of anywhere in the UK. (Waits to be corrected)
I've always managed to get airborne before the start of the downslope but I've often wondered what it feels like to go over the "edge" while still on the ground.

Zlin526

20th May 2003, 02:14

QNH,

North Essex/South Suffolk tends to merge anyway..Its only just in Suffolk.

I've heard of (but not seen) a Prentice being flown out from Nayland! Not the worlds best performer in the R.O.C dept, as I'm sure anyone who's flown one will agree. Which makes me wonder how far down the hill he was before the wheels left the ground.

I was 'Lucky' enough to have logged 40 mins in one once, and was convinced we only got airborne cos the Earths curvature effect, and because we had a concrete runway! How the RAF ever accepted it into service will always amaze me.

A wonderful place is Nayland, and all credit to Tony Harris for keeping it special!