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Can I Land a plane ... or what?


Guest JRMobile
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Guest JRMobile

"Time now for Fun With A Porpoise. No, not Flipper's homage to Highlights magazine. Instead, we drop you into a Jabiru's PIC seat. You're cleared to land and, for test porpoises only, you are about to commit one of the most common (and preventable) landings errors: It's the bounce compounded by improper recovery. That oscillating up/down bouncing -- like a dolphin -- is called a porpoise. Air traffic controllers witness this on a depressingly regular basis and know that the average single-engine, tricycle-geared airplane will crash, break its nose wheel and slide like a belly-flopped sea mammal down the runway if a go-around is not initiated before the nose wheel impacts the runway for the (_____) time."

 

I got this one wrong and answered the "first" . The correct answer is the "third time" .

 

Can anyone shed some light on this as to why the 3rd contact is the critical number.

 

Cheers JR

 

 

 

 

 

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The first bounce :ah_oh: - you don't believe it, :yuk: but you have enough nerve and confidence to try again. :thumb_up:

 

At the second bounce 051_crying.gif.fe5d15edcc60afab3cc76b2638e7acf3.gif you realize you're not half the pilot you thought you were, but you can still land - right question.gif.c2f6860684cbd9834a97934921df4bcb.gif - I am a Pilot. :thumb_up:

 

At the third bounce :black_eye: your fundamental orifice takes over and you're training finally kicks in and you come to realize 040_nerd.gif.a6a4f823734c8b20ed33654968aaa347.gif that a real pilot would have gone around after the first bounce and now you're trying to save your aircraft and your life. :hittinghead:

 

So what about your DIGNITY:question: - remember your first solo when nobody saw how good you did. :thumb_up: Well don't worry, everyone in a 15 mile radius came to the airport today just to see your stuff up. 011_clap.gif.c796ec930025ef6b94efb6b089d30b16.gif

 

You'll be the popular topic for a short time until some other poor bastard 068_angry.gif.cc43c1d4bb0cee77bfbafb87fd434239.gif does the same or worse, thumb_down and you'll be off the hook. i_dunno

 

God I love flying. 006_laugh.gif.0f7b82c13a0ec29502c5fb56c616f069.gif006_laugh.gif.d4257c62d3c07cda468378b239946970.gif006_laugh.gif.0f7b82c13a0ec29502c5fb56c616f069.gif

 

regards

 

:big_grin::big_grin:

 

PS Now the good news - you'll only do it once.

 

 

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Bouncing.

 

There is no definative answer to this, certainly you cannot see the logic of saying the 3 rd is the answer. The first bounce is the time to re-assess, either go around or apply power to enable a correction or just (if the aeroplane has enough energy) allow it to descend amd hold off properly.

 

The one on groundlooping a tri-cycle undercarriage is incorrect too, in mt opinion, as ,while you can have a directional event with a nose wheel aeroplane, it cannot develop into a "groundloop" in the real sense as happens with a tailwheel aeroplane.

 

The tri-gear event is called wheelbarrowing, and once the weight is on the mainplanes, the situation becomes directionally more stable . The usual bad result of a nose-wheel fast turn is tippng towards the nose and wingtip. Nev..

 

 

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Guest JRMobile

Great answer Pete - your usual good humor 006_laugh.gif.0f7b82c13a0ec29502c5fb56c616f069.gif.

 

I got trapped when the question talked about "we drop you into a Jabiru's PIC seat" and as a Jab pilots who always tries to look after the nose wheel, knows that the first time is not going to be good!

 

And yes I do remember the first time it happened to me :black_eye: and was able to apply power after the second bounce for a go around (large pucker factor) at the time I put it down to wind shear but what I do remember is the speed with which it all went pear shaped. JR

 

 

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This is based on extensive scientific studies performed by the quiz author during his too many years as an FAA air traffic controller (tower).

 

Conclusion: 1) The control tower is a great place to watch bad landings, and 2) Pilots who insist upon landing nose-wheel first will bounce. Boing!

 

A tiny first bounce can be salvaged with proper pitch and, perhaps a spritz of power. But, should the poorly-trimmed, nose-heavy airplane smack nose-first a second time -- Bwa-Boing! -- the resultant bounce will be higher with staggering consequences. If left uncorrected -- by now the only out is a go-around -- the abused airplane will absolutely, no-doubt-about-it, smack the runway a third and final time. At this point the nose strut, plus all its delicate and expensive parts, will shatter, bend, and generally explode, leaving the PIC, who's not really in command, wondering, "Wha-happened?"

 

Remember: There are only two landing-gear wheels in a tricycle-geared airplane -- the left and right mains. The nose wheel is there to keep the propeller off the pavement; it's not for landing. One more reason to fly tail-draggers.

 

 

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I'm astounded.

 

A bit over the top Ian, but I am amazed that you would take a pro tailwheel position. Good for you. Nosewheels are not strong structures. I believe about 3 years ago( could be more) that 3 aircraft landing at Avalon,(Jabiru's) damaged their nosewheels by landing downwind, during an airshow where they were subject to air traffic control. A view put to me by a very experienced pilot involved with the organisation of the Avalon airshow , is that the PIC, as the final authority as to how the aircraft that he "commands" is flown should have refused to accept a clearance (and DIRECTION (implied) to land with a downwind component that he/she was unhappy with. While the principles involved here are basic, the simple facts are, that to a pilot who is not familiar with "air traffic control" most will be a little overwhelmed by the situation that they find themselves in, and will not assert the authority that the system expects they will, to manage and to fly within the safe limits which their normal judgement would have dictated. The "frailties "of the nosewheel, in this instance, brought about the inevitable consequences. Nev

 

 

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What has downwind landing got to do with nosewheels. They should not touch the ground until well after the wings have stopped providing lift. Isn't the real problem letting the nosewheel touch with the tail in the air and putting too much load on it?

 

 

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What happened.

 

Ian ,I am only telling you what happened. I would suggest that when you land downwind, you can get an increase of airspeed due to windshear, and they obviously felt the need to put the aircraft on the ground and did so with excessive airspeed , and the nosewheels took the weight rather than the mains. Most low-time pilots are not trained in downwind landings, and probably have never done one. You are correct in saying that the airspeed should be bled off, and the aircraft landed on the mains. I would suggest that it is unfamiliarity. ..Nev..

 

 

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One more reason to fly tail-draggers.

Here, here!

 

But seriously, don't try to land the plane, just land the back end of the fuselage (I normally say the tailwheel, but this also works for planes with a training wheel

 

Arthur.

 

 

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Guest Maj Millard

Ok lets stir up some hornets here. Yenn is entirely correct when he suggests that you primarily land on the mains with the lowering of the nose wheel as secondary, once the wings have lost lift. A downwind landing is esentially the same technique except that you must expect, and be ready for, a higher over -the -ground speed, due to the tailwind, and lack of the normal headwind, into which you would normally flare.

 

Two ways to compensate for this is (1) get off the power earlier, for more bleed -off of airspeed., (2) carry a slightly higher angle of attack to compensate for the lack of lift on the nose that the headwind would normally give you. Actual touchdown speed should then be similar to normal.

 

It is fairly obvious to me after all these years, that Jabarus have both a 'less than strong enough' main landing -gear,(bolt failures/delaminations), and a painfully- obvious 'too-weak' nose leg, (especially under side loads), as amply demonstrated by many frequent failures. Are pilots trying to take it easy on the main gear, and therefore hitting on the nose leg ?.

 

Is it because there are a lot of student/solo landings in Jab aircraft ?. No excuse, a trainer should have a tough landing gear as a minimum requirement.

 

Why hasn't the Jab factory strengthened the landing gear, and especially the nose leg ?. The Lightwing Sport 2000 had nose-leg probs when it came out, they kept strengthening it, and now it is as strong as the Sydney Harbour bridge.

 

Another classic example of a too-weak landing gear, the Skyfox and Gazelle. When copied in Australia from the American Kitfox, the landing gear, (and unfortunatly other structural areas) was reduced to .035 wall thickness chromemoly tube, one would imagine to save either weight, or money, or both. Three good bounces in one of those little babies, and bong, there goes the .035 landing gear tube with resulting wingtip and prop/engine/fuselage damage. Not good enough for an aircraft destined for the training role. The American Kitfox doesn't have a similar history of gear failures, or aileron hanger failures for that matter.

 

As one who has designed and built an aircraft from scratch, I know from experience that there are two main components on any aircraft that must not fail, ever !. The wings, and the landing gear. Landing gear must be strong, with about a three to one factor of strength, to what it may reasonabily be expected to be subjected to, especially in an aircraft used for training. Then you go out and do your best to become consistant with your particular aircraft's landing technics. 024_cool.gif.7a88a3168ebd868f5549631161e2b369.gif

 

 

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Ok lets stir up some hornets here. … A downwind landing is essentially the same technique except that you must expect, and be ready for, a higher over -the -ground speed, due to the tailwind, and lack of the normal headwind, into which you would normally flare. Two ways to compensate for this is (1) get off the power earlier, for more bleed -off of airspeed., (2) carry a slightly higher angle of attack to compensate for the lack of lift on the nose that the headwind would normally give you. Actual touchdown speed should then be similar to normal.

G’day MajMill,

 

Bzzz, Bzzz, Bzzz, this hornet is going to call you on this one.

 

You’re right about the higher ground speed, but your approach airspeed should be the same as usual, regardless of whether you have a tail or head wind. Groundspeed is not a cue for a safe approach and landing. :ah_oh:

 

As an example, the beer can has an approach speed of 60 knots, slowing to 55 knots over the fence and into the roundout.

 

With a 10 knot headwind, 30 degrees of flap at MTOW on a standard day, I should roundout and flare just above the runway and then float along until touchdown just on the stall at 42knots with a ground speed of 32 knots. With a 10 knot tailwind in the same configuration, I’ll still touchdown just on the stall at 42knots airspeed, but with a 52 knot ground speed. To compensate for a downwind landing I’ll have to factor for a longer roll out and having to bleed off the extra energy by braking owing to the higher ground speed.

 

I’m reluctant to accept that getting off the power early and carrying a higher angle of attack is the correct way of compensating for the increased ground speed of a tailwind/downwind landing. To me, it sounds like heading toward a low and slow stall on approach - splat!

 

Cheers!

 

Steven B.

 

And if I’m mistaken, I’m sure Motz will tear me a new one! :confused:

 

 

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The other factor.

 

Ahlocks, you have ignored the other factor . The windshear. As the wind at height (say 40 feet) may be ,say 15 knots tailwind, and at flare height 8 knots tailwind. The seven knots difference translates as an airspeed increase, which the pilot is not expecting. Jabiru's are fairly low drag aircraft, so they float excessively if you are too fast. (Especially if the engine Idle speed is a bit high as well), it doesnt want to land, so you land with too high an airspeed which must end up being nose down. Nev..

 

 

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006_laugh.gif.0f7b82c13a0ec29502c5fb56c616f069.gif..yea goodonya ahlocks.. No more new orrifie tearing allowed..;)

 

The thing that scares me about downwind landings isn't the nose gear or any other part of the acft collapsing.. Its the risk of having a complete stuffup and killing yourself..

 

Lets take Nevs example of the 15 tailwind at 40 ft, which will invariably drop to around half that at flair height ( local things considered of course).. so you experiance this sudden increase in headwind( decrease in tailwind) and the jab wants to keep on floating, and floating and floating, and you look out the window and think gees im hot, this is to quick man... better get out out and use the other strip before i float through the fence at the other end,.. and apply full power, raise the flap(if you had it out) raise the nose for best angle climb at say 65 kts.. now, your groundspeed is still hotter then normal, and the brain perceices this as extra airspeed, then at 40 feet you get the tail wind increase (remember that tailwind from the approach) so airspeed reduces without a visual cue other then the IAS, no problem you say, im hooking allong, i can raise the nose a bit more, and ssssqqqquuueeeeaaaakkkkkk goes the stall horn and you get a very close look at the local horticulture.

 

So i reckon that the extra groundspeed you 'see' as a change in the picture can act against you if your not on the spot johnny with the IAS..And if you set best angle climb and then get an increased tailwind, well, the angle is going to be well upset already by the tailwind isn't it. so that tree at the other end youve climbed out over time and time again may just be tall enough to tickle the U/C..

 

There.. evryone still has orriginal orrifie..;)

 

cheers

 

 

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Maj....mate....

 

Originally Posted by Maj Millard viewpost.gif

 

Two ways to compensate for this is (1) get off the power earlier, for more bleed -off of airspeed., (2) carry a slightly higher angle of attack to compensate for the lack of lift on the nose that the headwind would normally give you. Actual touchdown speed should then be similar to normal....

 

 

please have a rethink about this.....pretty please:thumb_up::big_grin:...010_chuffed.gif.c2575b31dcd1e7cce10574d86ccb2d9d.gif

 

 

 

 

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The Jabiru J160c and the J170 have a very strong main undercarriage, (from the 400 series). Just keep the nose wheel off the deck and she's sweet. Not sure about the earlier Jabirus or the current J120.

 

regards

 

 

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Ahlocks, you have ignored the other factor . The windshear. As the wind at height (say 40 feet) may be ,say 15 knots tailwind, and at flare height 8 knots tailwind. The seven knots difference translates as an airspeed increase, which the pilot is not expecting. Jabiru's are fairly low drag aircraft, so they float excessively if you are too fast. (Especially if the engine Idle speed is a bit high as well), it doesnt want to land, so you land with too high an airspeed which must end up being nose down. Nev..

Nah, still don't totally agree with you Nev. This is the 'stall while turning downwind' conundrum in another guise.

 

The aircraft is travelling within a moving body of air. As the tailwind subsides the aircraft's ground speed will subside with it. The aircraft will still be travelling along through the body of air at the same speed. Unless your talking real windshear i.e. a sudden reversal.

 

Touchdown speed is air speed and angle of attack plus a couple of other variables. (weight, air density etc.) and remains fairly constant. Ground speed is a variable related to wind speed and direction and is going to affect the distance you're going to travel while shedding energy to touchdown and while rolling out.

 

I'm am beginning to wondering if MajMill was referring to angle of decent rather than angle of attack though.....

 

 

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downwind groundspeed component. for each kt of downwind gives double over the ground. at least it felt that way with hanggliders and parachutes when i did the odd downwinder.

 

 

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Guest Maj Millard

My thanks to Ahlocks and Motzartmerv for your comments. I have taken them onboard and have rethought the whole thing.

 

The following may be considered to be valid in my case:

 

The majority, (80% or so) of my total time is in taildraggers. My comments on landing downwind, references mainly to tail draggers. On the occasions where I do fly something with a training -wheel up front, it is not usually mine, and I would be reluctant to do a downwinder in somebody else's plane, unless (a) I had no choice.,or (b) the owner was on board and had no problem with it.

 

After over 20 yrs flying ULs I fly mainly by instinct and feel these days. I certainly don't hang on the ASI on finals, although I do take a quick peek over the fence.

 

I generally do either a wheeler, or a 3-point landing, depending on how it feels, although most landings are 3 pointers. On a recent SS4 Storch ferry flight Julia Creek-Townsville I did six landings all up, in all winds.Three were wheel landings, the rest 3-pointers.

 

As the late great Bill Starke would often say "you do whatever you have to do at the time !"

 

Since I don't like putting aircraft on their noses :faint:generally a downwind wheel -landing is out of the question for me, although ag pilots will do them all day long, together with heavily-loaded downwind takeoffs.

 

I am never shy in tackling a downwind take off or landing. In fact I make a point of doing one now and then if I can, to keep the skills alive.

 

099_off_topic.gif.20188a5321221476a2fad1197804b380.gif So we are talking about a downwind landing in a taildragger ok.

 

Granted you are moving downwind in a moving mass of air, at the same speed as that mass of air. Any power you are carrying above what you need to stay in the air is increasing your speed over the ground. The same applies as though you were landing into the wind. You want to touch down as slow as possible, with adequet control, and definetly in a 3-point attitude(taildraggers) or on the mains with nose high in a trycical gear.

 

The higher than normal angle of attack I refer to, is right at flare, to assure the aircraft contacts in a 3-point attitude, and also to "stick' the aircraft on, as a higher than normal contact speed could reasonably be expected, landing downwind, if you haven,t got rid of the extra speed.

 

I have pulled off many downwinders over the years using the above techniques (and a dash of luck), and have yet to go 'splat' as Ahlocks may suggest. If you really want to up the excitement level sometime, try down -wind, down -hill, with no brakes !! 024_cool.gif.7a88a3168ebd868f5549631161e2b369.gif

 

 

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The higher than normal angle of attack I refer to, is right at flare, to assure the aircraft contacts in a 3-point attitude, and also to "stick' the aircraft on, as a higher than normal contact speed could reasonably be expected, landing downwind, if you haven,t got rid of the extra speed.

Ahhh… What you say makey more sense now…..exclamation.gif.7a55ce2d2271ca43a14cd3ca0997ad91.gif

 

I have pulled off many downwinders over the years using the above techniques (and a dash of luck), and have yet to go 'splat' as Ahlocks may suggest. If you really want to up the excitement level sometime, try down -wind, down -hill, with no brakes !!

Now that you’ve clarified that it’s during the flare, splat! seems far less likely. Try the same technique during the approach phase and report back with the results though. That’s where I was getting concerned.

Down wind, down hill and no brakes? Nah, a bit like tail draggers… doesn’t do anything for me. :yin_yan:

 

Cheers!

 

Steven B.

 

 

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