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When do you lose the ability to fly your aircraft?

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When do you lose the ability to fly your aircraft?

Old 30th Mar 2022, 18:19
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I like to always fly it onto the runway with extra energy to prevent a gust of wind making me look stupider.
vs.
FTAOD you should always land at the minimum airspeed you can, even if you need full control deflections to keep your line. If you can't do that then find another runway.
I think we could have a good long debate on that whole issue -- maybe in a new thread!

Yes one doesn't want to start landing way too fast, especially if talking about a larger heavier aircraft that might be more runway length limited. Or forcing the plane to the ground, leading to bounces or porpoising.

[Edit: what I wrote below isn't that different from the first time, but I guess I'm trying to describe the whole process again to try to get the explanation through.]

But normally in a light plane I don't want land at absolute minimum speed either. In typical cases just flare, let it descend slowly to the runway at a rate acceptable to the aircraft's landing gear, plant it firmly but not hard, and transition to rolling out on the runway. One doesn't want to be eking out more and more flare, nose getting way high, with stall horn blaring (in a certified aircraft), more likely to get drifted by crosswinds -- especially if one has already straightened out, as one might not know whether it will be 1 or 4 more seconds before for the plane runs out of lift and drops the last couple inches to the ground. Going for the absolute minimum speed leaves the plane susceptible to every little bit of turbulence or gust. Fun to do in very calm or zero turbulence conditions, but not for everyday.
(Obviously there are going to be variations by aircraft type, how much the gear absorb any landing shock, whether it is a regular tri gear landing or crosswind one-wheel landing by a tail dragger, etc. so I'm not trying to cover every possible situation.)



Last edited by pchapman; 31st Mar 2022 at 19:25.
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Old 30th Mar 2022, 19:00
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Rick Durden explained it well in this Avwebb post, so I'll just link to it
https://www.avweb.com/features/the-pilots-lounge-102-the-last-10-feet/
(Sorry I can't work out how to do it!)
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Old 30th Mar 2022, 20:58
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Aircraft with low mass and high drag are different from larger aircraft such as the C150 and Pa38, especially if they have a nthin wing section.The loss of airspeed and lift is sudden. Microlites and near-microlites need a different technique to do smooth landings.

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Old 30th Mar 2022, 21:58
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Heston,

Thanks for the link to that excellent article:
https://www.avweb.com/features/the-p...-last-10-feet/
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Old 30th Mar 2022, 22:44
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One doesn't want to be eking out more and more flare, nose getting way high, with stall horn blaring (in a certified aircraft), more likely to get drifted by crosswinds -- especially if one has already straightened out, as one might not know whether it will be 1 or 4 more seconds before for the plane runs out of lift and drops the last couple inches to the ground. Going for the absolute minimum speed leaves the plane susceptible to every little bit of turbulence or gust. Fun to do in very calm or zero turbulence conditions, but not for everyday.
Sorry pchapman but airspeed = lift: too high an airspeed assists any gust and will not prevent it albeit the controls are very marginally more effective.. At some point you must land; the aeroplane need not be kicked straight early. a little late will do no harm to a safe landing. Once in contact with the runway then the aircraft is most vulnerable to gusts if the speed is too fast. You need to be as heavy as possible on touchdown and this will be at the lowest speed and with the most effective braking. Landing too early, too fast and the aircraft is light and the application of brakes will be unpredictable and may be asymmetrical in effect should the weight from the wheels not be equal.
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Old 31st Mar 2022, 15:50
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Aircraft with low mass and high drag are different from larger aircraft such as the C150 and Pa38, especially if they have a nthin wing section.The loss of airspeed and lift is sudden. Microlites and near-microlites need a different technique to do smooth landings.
Sorry, I disagree with that entirely. I fly a C42 and the landing technique is no different, the wing doesn't suddenly stop producing lift - stalls are ridiculously benign whether clean or with full flap.

You do notice and feel gusts more on final approach due to the low inertia and mass but the response to power is so quick there is no problem.

Agree that the article Heston linked to is excellent.
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Old 31st Mar 2022, 18:36
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"Microlites and near-microlites need a different technique to do smooth landings."

Absolutely Spot On, true microlites, e.g. Rans S4 need power on through landing if one is to avoid falling heavily. The 'standard' power off and glide the last bit is not any good, uness of course in an engine out case when a steep dive and excess of speed will let you get away with it. [Reference RansMail articles).
Even as an 'aeroplane' the Rans S6-116 model can run out of lift quite suddenly, likewise the Reality Escapade needs care (viz. u/c write off by a very experienced Jodel pilot when executing a classic gliding final and falling the last bit.
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Old 31st Mar 2022, 19:21
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Originally Posted by Fl1ingfrog View Post
Sorry pchapman but airspeed = lift:
Let's not forget that angle of attack is in there somewhere too! Getting the nose down for tri gear should make a big difference (depending on all the angles and incidence and wing sections involved).

The Avweb article sounds interesting although will take a while to read through. Sounds like it involves someone who was touching down 20 mph faster than stall. Different from the, say, <5 mph that I was thinking about.

If you want to land shorter, plant the aircraft down on the ground at a light descent rate after the flare, get the nose down (for tri gear) to kill lift so you can start using brakes. (Unless its some aircraft where aerodynamic braking were better than wheel brakes.)
Don't keep the nose way up in the air, floating along another few hundred feet, trying to eke out just another few mph less airspeed, right to the minimum, while floating along along inches above the ground, waiting for an unpredictable stall point (because you can't look at the airspeed at this point and or its effectively off the clock anyway), possibly exposed to unexpected ground contact from any gust that moves you a few inches down, while you are also unsure of when to take out any crosswind correction, because you don't know when that stall will come and you'll touch down.

I thought in larger aircraft and the military they also tend to like planting the aircraft down instead of getting to the very minimum possible airspeed. And that's in aircraft where approach speed control is more important, and too fast touchdowns may lead to undesirably long landings.

Anyway, it's a good agree-to-disagree sort of topic. Hopefully we are talking about issues that don't totally overlap -- minimum speed vs. a reasonable speed slightly faster vs. way too fast touchdowns.




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Old 31st Mar 2022, 19:31
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Originally Posted by pchapman View Post
Let's not forget that angle of attack is in there somewhere too! Getting the nose down for tri gear should make a big difference (depending on all the angles and incidence and wing sections involved)....

If you want to land shorter, plant the aircraft down on the ground at a light descent rate after the flare, get the nose down (for tri gear) to kill lift so you can start using brakes. (Unless its some aircraft where aerodynamic braking were better than wheel brakes.)
Don't keep the nose way up in the air, floating along another few hundred feet...
That is just so bad it's not even wrong!
- you risk breaking the nose leg- you shouldn't need to "kill lift" because you should be slow enough that there's sufficient weight on the wheels anyway- if you can float another few hundred feet then your approach speed was too fast

And anyway, what do I do in a Piper Cub or other taildragger? And don't tell me they need a different technique. They aren't called 'conventional gear' for no reason.
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Old 31st Mar 2022, 21:37
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If you want to land shorter, plant the aircraft down on the ground at a light descent rate after the flare, get the nose down (for tri gear) to kill lift so you can start using brakes. (Unless its some aircraft where aerodynamic braking were better than wheel brakes.)
I strongly advise you against this. Pushing the nose down will mean that you become a wheelbarrow, the main wheels kept light on the ground by the main plane above. you are very vulnerable to gusty conditions by doing this especially if the surface is wet. Braking will not become fully effective until the aircraft has slowed. By holding the nose up you induce aerodynamic braking plus with the downforce from the tail plane also increasing the weight of the main wheels and friction and therefore the braking when it becomes appropriate.

You can be assured that aerodynamic braking is many times more effective than the wheel brakes during the early stages of the landing.
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Old 31st Mar 2022, 22:58
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Every SEP instructor's mantra is 'MORE RIGHT RUDDER'.
Second to this is 'DON'T PUSH'.

TOO
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Old 1st Apr 2022, 01:11
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It is tough to argue the subtleties of these situations; one gets buffeted on all sides.
One person says the plane might have too much lift after touchdown and still be light on its wheels. So I say, lower the nose to reduce the angle of attack. Which isn't supposed to be the same as slamming the nose down to wheel barrow, or slamming it down so hard to risk structural damage. Or I get told that despite lowering the nose to reduce lift, I'll still have so much lift that the plane will STILL be light on its main wheels. I do like aerobraking too, and discussing aerobraking vs. wheel brakes at different speeds is a good topic. But of course at some point you do have to lower the nose -- otherwise on some aircraft if you aerobrake too long you run out of elevator effectiveness all of a sudden... and the nose slams down harshly. And while I explicitly say I'm only talking about tri gear, I'm also challenged about why taildraggers should be any different. Yes, I do suggest a different technique....don't try to lower the nose on a taildragger all the way to the ground after landing, that gets expensive on props! (Hmm, for those who debate taildragger wheel landings vs. 3-point landings, how can the actual touchdowns possibly differ if everyone should be landing at minimum possible speed?) While there are some good points to debate in all this, sometimes it seems that no statement can be made that can't be over-interpreted. If I say to pull up from cruise flight, someone will say that'll pull the ruddy wings off!

Then we also have issues of terminology: I never used the term "push" but then someone else used it and then someone else complains about that! Clearly lowering the nose after landing may just require a relaxation of back pressure and is not likely to require any push on the stick, which could indeed be detrimental to the nose gear. An instructor in particular would want to be careful with terminology.

Anyway, I'm always willing to learn and re-evaluate the interplay of different factors in handling an aircraft, but I'm not seeing enough to convince me that keeping on going to the very stall is particularly useful on landing.
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Old 1st Apr 2022, 10:30
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Originally Posted by mikehallam View Post
"Microlites and near-microlites need a different technique to do smooth landings."

Absolutely Spot On, true microlites, e.g. Rans S4 need power on through landing if one is to avoid falling heavily. The 'standard' power off and glide the last bit is not any good, uness of course in an engine out case when a steep dive and excess of speed will let you get away with it. [Reference RansMail articles).
Even as an 'aeroplane' the Rans S6-116 model can run out of lift quite suddenly, likewise the Reality Escapade needs care (viz. u/c write off by a very experienced Jodel pilot when executing a classic gliding final and falling the last bit.
The C42 is a true microlight and is used extensively as a trainer - you do not need power on through the landing.
Hold the speed with attitude and maintain the sight picture with power - basic stuff - but when you come to round out/flare you want the throttle closed. A gentle flare will reduce the speed and RoD and as the main wheels touch, keep the nose coming up to wash of the speed before allowing the nose wheel to contact the ground.

BTW I learned on Jet Provost back in the day and the RAF aimed for a threshold speed and flared with the throttle closed to land about 85 Kts. The only reason to plant the landing was if the runway was very wet in order to prevent aquaplaning.
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Old 1st Apr 2022, 18:08
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Originally Posted by [email protected] View Post
The C42 is a true microlight and is used extensively as a trainer - you do not need power on through the landing.
Hold the speed with attitude and maintain the sight picture with power - basic stuff - but when you come to round out/flare you want the throttle closed.
Weeell...
In the sense that it was meant above, a C42 is not a "true"microlight specifically because it can be landed more like a slightly heavier GA aircraft; that is with the throttle closed. Yes of course it is a microlight and it is widely used as a trainer, but folk who learn on it can come a cropper once qualified if they try to use the same landing technique in older designs like, say, an Xair, which definitely do need a different technique.
In any case it depends on what you mean by landing with the throttle closed. Yes flare with it closed in a C42 if you must, but don't close it a 50 feet as you come over the hedge - that might work for you in a C150 but not in a C42. I've never flown a jet so I've no idea about the correct technique in a JP.
If the only microlight you've flown is a C42 I strongly recommend getting some differences training before moving to other types (doesn't have to be an instructor, just someone you trust who knows the type).
As a general comment - it's microlight not microlite.
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Old 1st Apr 2022, 19:34
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I think some of you don't understand the difference between low inertia and low speed. It's entirely possible to land (for example) an x-air engine stopped. The round out is more dramatic if you like, as the angle through which you need to rotate is quite large, and the hold off (deacceleration) won't last very long, due to the low inertia. It does require some precision and, dare I say, skill. Practice helps.
Likewise, a cub can be plonked on the runway at quite a high speed ( for a cub) and kept there as long as you a) put it on the mainwheels and b) keep it rolling on the mainwheels with a moderately firm stick forward. Flying conventional gear does not always require a three point landing. Sometimes it's better to land one wheel at a time. Again, practice helps.
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Old 1st Apr 2022, 20:12
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Originally Posted by Piper.Classique View Post
...possible to land (for example) an x-air engine stopped. The round out is more dramatic if you like, as the angle through which you need to rotate is quite large, and the hold off (deacceleration) won't last very long, due to the low inertia. It does require some precision and, dare I say, skill..
I've done exactly that many times, so thank you

The point is that in a low inertia draggy machine if you close the throttle at a height at which everything would work well in a spam can, you will quickly slow down and hit the ground earlier than you expected with a high descent rate. It's the change in power that catches you out, not having no power. How would we do PFLs and real engine out landings?
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Old 1st Apr 2022, 22:23
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So the only bone of contention is when you actually close the throttle - surely that depends on your approach angle and airspeed.

If you have the correct angle and airspeed - shallow = more power and steeper = less - then you will still want to close the throttle just before you flare, regardless.

The idea of holding power on all the way to the ground is anathema to most people's idea of correct technique.

A glide approach is just a steeper version - not by much - and works on microlights and heavier aircraft so what is the issue?

No-one is advocating closing the throttle at 50' as a practice - you use the throttle for as long as you need to to maintain the approach angle but you still close it before you flare.
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Old 2nd Apr 2022, 09:30
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Heston, I think we are singing from the same hymn book here. I honestly can't think of any heavier than air flying machine that can't be landed without use of the engine.
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Old 2nd Apr 2022, 10:36
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Should be noted that the POH/FM landing distances given are calculated from 50 ft above the threshold with the throttle closed. Other than noting this there cannot be a rule with regard to the throttle closed or not. Some types nose weight can be heavy and therefore retaining additional power can help. Certainly in gusty conditions the extra slipstream is invaluable by enhancing the effectiveness of the rudder and elevator for single engine types.
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Old 2nd Apr 2022, 10:37
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I honestly can't think of any heavier than air flying machine that can't be landed without use of the engine.
Space-X Rocket?
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