Flapless landing
 

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

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.

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...

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.

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.

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'.

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.

If 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.
In a strong crosswind there won't be much headwind!

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.

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:

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

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.

Flapless Landings
 

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?

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.

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.

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.

thanks
 

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

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).

Another reason for flapless landings.
 

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.

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