Flapless landing

[elcol]

Anybody know what the increment to the landing distance is for a flapless landing on a PA28.
Thanks

[Final 3 Greens]

elcol

I don't have a flight manual to hand, but IIRC this data is not published in it (at least for the -140, 151, 161 and 181) and you have to look at the flaps 40 data and make an educated guess.

Again, IIRC,the approach speed is about +5knots.

If you need to know serioulsy (i.e. you are field length limited), I'd book a couple of circuits with an instructor, get a briefing and then take a view on the difference.

Have done many over the years, I don't recall it being dramatic, but then again I was using runways with 700-1650m length, so not really length limited.

[24Carrot]

elcol

Just ball-park, back-of-the-envelope numbers, so please don't rely on them:

If you touch down at a 10% higher stall speed that's 20% extra energy to lose in the ground roll, which would be about 20% longer.

During the "flare" you have to lose about 10% extra speed energy with maybe a 25% "better" Lift/Drag ratio (which is 25% less drag to slow you down unfortunately) so it could take 30-40% extra air distance. Obviously the wind will affect the distance over the ground.

Some practice on a long runway is probably the best way to find out the real answer...

[FREDAcheck]

An educated guess might be based on the landing roll distance increasing with at least the square of the landing (ground) speed. Each stage of flaps reduces the recommended approach speed by 3mph (from 85mph approach, flapless) on a PA28.

Assuming you actually manage to touch about 5mph lower than the approach speed, then the increase in landing roll from full flap to no flap would be at least 27%. I say "at least", because I think landing roll increases by more than the square of the speed as brakes are less efficient at high speed, but stand to be corrected. Also, the faster you go the less accurate the touch down (as it's all happening faster in relation to your reaction time).

Edit: missed 24carrot's reply, but would agree the actual increase is likely to be more (rather than less) than the 27% minimum figure I give.

[Choxolate]

CJ Boy
Why would you want to do a flapless landing in a PA 28?
Apart from being part of PPL syllabus possibly in case it actually happens one day and the flaps jam in the up position or the mechansim fails or ... well I'll leave the rest to your imagination.
I know it may come as a surprise but sometimes mechanical things fail unexpectedly for a whole variety of possible reasons.

[pploony]

Also flapless landings give better controllability in strong winds/crosswinds.I have done them regularly in both the PA28-161 & 181 versions.It handles very well in these conditions,and the ground run is not that much greater due to the 'headwind'.

[cjhants]

depends what type of PA28 you are flying. the more modern warrior 3`s can float a long way before the speed bleeds off enough to want to land. the older chrokees will sink a bit more quickly as the speed bleeds off.

assume you will be doing it with an instructor, so do it as per the brief. my guess is that he/she will let you practice flapless on a longish runway, advise you to come in a bit fast and aim for the numbers so you can experience the float compared to a flapped approach. its a different feel to your normal approach, with a diffent flatter picture out front. but do it as per the briefing rather than what you have been advised on a forum.

i seem to remember when i was training on warrior 3`s the FI got me to do an approach and touch and go and 70kt or so, and then approach at about 5kt faster. the extra float in calm conditions meant we had to call it a full stop.

[Whopity]

Also flapless landings give better controllability in strong winds/crosswindsIf I was landing a PA28 in a 28-30 kt X-wind I would take full flap every time; and I teach accordingly. I would not dream of landing flapless, drifting sideways across the runway, waiting for something to happen. Maybe if it was very gusty, I would reduce to 25 degrees flap but no more.
the ground run is not that much greater due to the 'headwind'In a strong crosswind there won't be much headwind!

[bingofuel]

If you land (or attempt to) a PA 28 in a 30kt crosswind I would imagine you are in uncharted territory, did not the test pilot only demonstrate it up to 17kts?

[Final 3 Greens]

If you land (or attempt to) a PA 28 in a 30kt crosswind I would imagine you are in uncharted territory, did not the test pilot only demonstrate it up to 17kts?

Yes, it was demonstrated at 17, not limited to 17.

I've landed one in a 25 knot crosswind without any drama. It was a steady wind. (I am just a regular PPL, no super hero skils.)

Also agree with Whopity about using full flap where possible, although I might take the final stages quite late, to keep a little more lateral stability further up, where there may be stronger gusts.

Nonethless, being current on flapless seems to be sensible, any mechnical system can fail (one hopes, symmetrically.)

Flapless landings in a PA28 are really not a big deal nor very difficult - speed control on the taper wings is important, but that is the same for all landings on these aircraft.

The OP asked a precise question about the incremental distance, for which there is not a POH answer unfortunately, IIRC.

[Vone Rotate]

Just a thought, where would you stand if you stacked a PA28 in a 30kt x-wind in and aircraft demonstrated up to 17kts insurance wise? Would you still be covered?

God forbid, if anyone got injured how would you stand against being sued?

I'm sure it has more to do with rudder authority than the highly experianced test pilot could't be ar*ed to find a stronger x-wind than 17kts.

We all know best hey, who needs the POH anyway!:ugh::ugh::ugh:

[Final 3 Greens]

Just a thought, where would you stand if you stacked a PA28 in a 30kt x-wind in and aircraft demonstrated up to 17kts insurance wise? Would you still be covered?

AFAIK you would be covered, since the 17 knots component is a demonstration, not a limit.

I'm sure it has more to do with rudder authority than the highly experianced test pilot could't be ar*ed to find a stronger x-wind than 17kts.


I would rather that Ghengis or a similarly qualified person answered your question, although I have my own view.

Having said that, I am certainnly not a test pilot nor 'ace of the base' and there was more than enough rudder authority to cope with a steady 25 knots.

Had it been gusting strongly, I would have diverted to a field with a more into wind runway, but for reasons of pilot skill rather than airframe limitation.

I would have done the same in a Bulldog, which has a lot of rudder authority.

[machonepointone]

Just for the record, the POH for the PA28-161 states "In high wind conditions, particularly in strong crosswinds, it may be desirable to approach the ground at higher than normal speeds with partial or no flaps."

However, what would Piper know about landing a Warrior in strong crosswinds?

[BEagle]

However, what would Piper know about landing a Warrior in strong crosswinds?

From what you've written, not very much it would seem.

Why fly at higher speed in an unfamiliar configuration when the crosswind is 'strong' - whatever that might mean.

I agree with Whopity; I once went to Kidlington to collect another aircraft planning to land on the westerly runway. When we got there, they told us that it was waterlogged (no mention of that when we rang beforehand....), so we'd have to use the southerly. There was a 25-30 kt surface wind, but the aircraft was easy enough to fly in those conditions with full flap and 65KIAS approach speed.

[Whopity]

I have landed a PA28-180 with 35 kts X wind. The student on that trip who was an experienced PPL doing an IIMC course wanted to add about 15 kts, 5 for X-wind, 5 for granny and another 5 just in case. If he had continued at this speed he would have drifted off the very wide runway. With the correct speed and a slightly angled approach there was no problem at twice the demonstrated maximum using full flap.

[Final 3 Greens]

"In high wind conditions, particularly in strong crosswinds, it may be desirable to approach the ground at higher than normal speeds with partial or no flaps."

Isn't that the most beautfully ambiguous statement ever?

It sounds as if it was written by a lawyer.

What is the definition of 'high wind'?

What is the definition of 'strong crosswinds'?

What is the definition of 'approach the ground'?

What is the definition of 'higher than normal speeds'?

What is the definition of 'it may be desirable'?

What is the definition of 'partial or no flaps'? surely they mean flaps set ;)

This sentence contains 26 words, but little meaning as far as I am concerned.

Probably there for product liability reasons.

[elcol]

Hi Guys
Thanks for all the interesting replies.
Obviously the bottom line here is that there is no given increment for a flapless landing only one derived from experience which is a bit disconcerting really.
The CAA safety sense leaflet makes no mention of it either.
http://www.caa.co.uk/docs/33/ga_srg_09webSSL07.pdf

Anyway thanks again,

elcol

[bjornhall]

AFAIU the reason for using less flaps in a crosswind is that it allows you to land at a higher speed, giving better rudder efficiency and smaller drift- and bank angle. Whereas one reason for using less flaps in high or gusty winds is that it makes it easier to keep the nose wheel from touching down first. Right?

I don't do it that way, since I think there are other and stronger reasons why using more flaps is a better idea, but I can at least see the point... :)

But there is no way I would do a no flap landing in a PA28 unless there was a lot of extra runway available... Less problem in a C172, where the POH contains the needed data (35% longer landing distance with flaps up).

[Final 3 Greens]

Bjorn

As I understand it, when you take flap, you change the wing profile (spanwise) and create more lift in the centre, less at the tips.

So the wing has less lateral stability in gusts.

Thinking of the inboard stall strips on a PA38 seems to align with this, as you want more lift towards the tips, to maintain lateral stability and control.

Nonetheless, as previously declared, I want to take the max flaps I can, for the reasons you stated.

[liam548]

these are the speeds I use for the PA28

lift off- 55kts

climb out with 2 stage flap 65-70kts

climb clean 80kts or 65 kts for Vx

cruise 100kts (at around 2300rpm)

base leg 75kts

Final 70kts

Final approach short runway 65kts

Final flapless 75kts

sorry forgot to mention these are for a Warrior

[Captain Stable]

The inboard stall strips are merely to ensure that the wing stalls from the root outwards.

liam, you didn't specify which version of the PA28 your speeds are for - they are significantly different for different versions - Cherokee, Warrior, Archer, Arrow II, Arrow IV, Arrow IVT, Dakota...?

[Intercepted]

What a mess!

I was reading this thread from the beginning and not until the last post (Captain Stable) it was mentioned the importance of stating what type of PA28 you are talking about.

Some people are referring to PA28 as it was one model. You should know better if you are going to post such important things as landing speeds.

The original question didn't state what model of PA28 to refer to either. I know my personal flapless speeds for a 140 and a 161, just tell me wich one you are interested in.

[Final 3 Greens]

Capt Stable

The stall strips ensure that the outer wings generate lift, when the inner wings have reduced or no lift, thus assisting lateral stability (and providing effective ailerons)

What would happen if the outer wing stalled first?

What happens if you take flaps and increase the lift in the inner wing section?

Reduced lateral stability.


Intercepted

Why don't you read the original question again? The OP wishes to know the incremental landing distance, not the approach speed.

The type of PA28 is irrelevant, because this data is not published in the POH.

[Captain Stable]

The stall strips ensure that the outer wings generate lift, when the inner wings have reduced or no lift, thus assisting lateral stability (and providing effective ailerons)

What would happen if the outer wing stalled first?

What happens if you take flaps and increase the lift in the inner wing section?

Reduced lateral stability.I'm not quite sure what you're trying to say here. The inboard stall strips have no effect whatsoever on airflow over the outer sections of the wing, so cannot ensure anything about what they produce. If the outer section of the wing stalled first, you would have significantly reduced lateral stability and therefore pronounced probability of wingdrop close to the stall leading to possible spin. Taking flaps reduces the stall speed by increasing lift and drag at low speeds.

When you say "the inner wings have reduced or no lift" do you mean that the wing is already at the stall?

I stick to what I said earlier - the inboard stall strips are to ensure that, clkose to the stall, it is the inboard sections of the wings that stall first, aiding lateral stability.

[Final 3 Greens]

Capt Stable

I think we are saying the same thing.

The stall strips cause the inner wings to stall first (producing reduced or no lift), which ensures that the outer wings are still producing lift at the same time, increasing lateral stability, as you say.

Taking flaps does indeed lower the stall speed by increasing lift, but only across the inner sections (where the flaps are), so thinking spanwise, lateral stability is reduced.

Im only using the stall strips as a reverse analogy, not as a direct comparison.

My hypothesis is that taking flaps in gusting crosswinds is (a) good, because it reduces the tendency to float and thus drift in the flare, but (b) bad, as it reduces lateral stability and thus resistance to gusts.

On the other hand, once one gets lower and the wind speed often reduces, I'll take flaps for the erasons Whopity has already outlined.

Hope this makes sense now.

[bjornhall]

How does having the outer parts of the wings stall first decrease lateral stability? And perhaps more to the point, how does that affect lateral stability when the wings are not stalled, as would hopefully be the case during the final approach and flare? I know having the inner parts stall sooner increases controllability, but I don't know how it increases stability?

Not using flaps allows for a higher approach speed, which increases aileron authority and lateral stability.

[BackPacker]

I've been thinking along the same lines as Bjornall. Lateral stability is not a function of the distribution of lift left/right/inboard/outboard, but rather a function of how the aircraft reacts to upsets of that distribution, and how easy it is to correct for this.

Along those lines, I would rather have the inboard portion of the wing generate most of the lift. If there is a gust then the resulting moment of roll will be less (moment = arm x force), compared to the situation where the outboard portion would do most of the work. And this means that less opposite moment (aileron input) would be required to keep the aircraft level.

I've experienced that long/slender wing aircraft such as gliders and a DA-40 are harder to fly in gusty conditions compared to short wing aircraft such as an R2160. Then again, there's also a difference in wing loading between these aircraft so their lower stability may not be entirely due to the larger moment generated by the larger wing.

[Malcom]

I cannot believe anything could ever go wrong with a European registered aircraft, with all that expensive gold plated maintenence.


Therein lies the mis-conception about Part M. Its not the maintenance thats gold plated. Its the paperwork trail that is, sometimes to the detriment of the maintenance jobs.:ugh:

[24Carrot]

I was taught that:

If the inner wings stall first, the pilot can notice an inadvertent stall while he still has aileron authority.

If the outer wings stall first, but not quite simultaneously, a wing can drop (at least the extra leverage makes it more likely).

which made sense to me.

FWIW I go with Whopity on the flapped crosswind approach: get it on the ground and rolling as slowly and as early as possible.

[Captain Stable]

[Uninformed, uneducated speculation=ON]
Given that the main problem in strong crosswinds on landing would be gusts, I agree that having the majority of lift close to the CofG is probably preferable. The main factor, of course, would be whether a gust will lift a wing beyond the capability of aileron to bring it back down again. In a dihedral aircraft like a PA28 this is going to be more of a problem than a plank such as the C152's wing.

I'm not sure whether the lower wing of a PA28 would also cause further problems with more pronounced ground effect than with a high-wing type.

Where that puts us on the question of flaps extended or clean wing for a crosswind landing I have no idea. I can see merit in both sides of the argument - but I'm not an aerodynamicist.
[Uninformed, uneducated speculation=OFF]

[liam548]

In very general terms and without being aircraft specific is it not good practice to have a slightly faster approach speed and possibly fly it clean while flying in gusty conditions on final?

Thats what I thought.

[BEagle]

No.





.

[liam548]

No.





.

ok then. I presume there is no general advice applicable to all aircraft?

[Lister Noble]

Fly it within the POH.

[trex450]

Just a thought, flapless or clean, if you have a strong crosswind (demonstrated limit or above) and you are using the crab method then is it not stupid to aim for a slow speed (near the stall) on touch down. My reasoning is that if, when you kick off the drift, you have not got enough rudder to straighten up and then have to go around then you are relying purely on the engine for acceleration. You are already at a height that does not enable the nose to be lowered without causing you to land, you are also drifting sideways across the runway, either way unless you have bags of power available then it is all going to get rather nasty. Of course the slower you are going the less rudder authority you will have anyway. Always better if possible to use the wing down (in my humble opinion) then at least you can fly it all the way onto the ground and know in advance that you are able to deal with the crosswind.

[Final 3 Greens]

trex450

I've never had any trouble landing a PA28 (or PA32) in a strong crosswind using the crab method (which my pax said is more comfortable than wing down), using the recommended approach speeds in the POH.

It is an inevitable fact that one will end up flying at slow speed in proximity to the ground during a landing ;)

I have gone around from about 10 feet one particularly gust day and there was no drama, just a nice clean climb away.

[BackPacker]

My reasoning is that if, when you kick off the drift, you have not got enough rudder to straighten up

I'm pretty sure that there's a certification requirement that the aircraft has to be capable of landing normally with a crosswind component that's x times the stall speed. (x=0.5 or thereabouts?) So you should have sufficient rudder and aileron authority to obtain the required wing down/sideslip attitude, and sufficient ground clearance in that attitude all the way down to the recommended touchdown speed, at the stated *demonstrated* crosswind limit.

Of course if you exceed the limits of the POH, you're a test pilot and all bets are off.

[homeguard]

NO! - is very unfair and unhelpful to a genuine question.

From the PA28 Archer 111:

'The gross weight of the Archer 111 with power off and full flaps is 45 KIAS. With flaps up this speed is increased by 5 KIAS'.

'In high winds, particularly in strong cross winds, it may be desirable to approach the ground at higher than normal speeds with partial or no flaps'.

The advantages of flap;

1) They allow a lower nose attitude improving the forward vision at various speeds, particularly useful when approaching to land.

2) Owing to the increased drag they allow a higher power to be used giving to the benefit gained from the increased propwash such as an enhanced fin/rudder, tailplane/elevator and also lift, lift increase is marked with most twin props.

3) Reduced approach speed of 1.3 the stall, owing to reduction in the in the stall speed with flaps deployed.

4) Reduced float during the hold-off

Disadvantages of flap.

1) Owing to the changes in the lift/drag co-efficient the aircraft is less stable in pitch,roll and yaw.

2) Less power over drag is available.

3) less range in pitch owing to the increase in angle of attack induced by flap.

Therefore in normal conditions the benefits of flap are clear but in turbulent conditions greater skill in control is required. To maintain the approach path or should a go-around be required say because of windshear then the ability to resist sink and/or to climb is impaired and requiring greater changes of power.

[liam548]

NO! - is very unfair and unhelpful to a genuine question.

From the PA28 Archer 111:

'The gross weight of the Archer 111 with power off and full flaps is 45 KIAS. With flaps up this speed is increased by 5 KIAS'.

'In high winds, particularly in strong cross winds, it may be desirable to approach the ground at higher than normal speeds with partial or no flaps'.

.

Is that not what I said above?

.....is it not good practice to have a slightly faster approach speed and possibly fly it clean while flying in gusty conditions on final?

Thats what I thought.

[Captain Stable]

The gross weight of the Archer 111 with power off and full flaps is 45 KIASKinda interesting units of measurement for weight/mass... ;) :confused:

[homeguard]

'The gross weight of the Archer 111 with power off and full flaps is 45 KIAS. With flaps up this speed is increased by 5 KIAS'.

should read:

'At the gross weight the stalling speed of the Archer 111 with power off and full flaps is 45 KIAS. With flaps up this speed is increased by 5 KIAS'.

thank you for noting the typing error.