Flat landings

[Thumpango]

Dear Instructors,

I wonder if you could take a look at my thread on the Private Flying forum under "Flat Landings/Examiners". The reason is that the approach speed for a fully flapped Warrior PA28-161 appears a little controversial. Please read the thread and any input would be most welcome as you are the teachers.

Many thanks for your help.

[Charlie Foxtrot India]

Thumpandgo,

I've put a reply on your other thread.

There is no question of what approach speed is correct, it is the one in the POH, it is the manufacturers recommendation and the one that insurance companies will expect you to observe in order to provide cover. 65 knots on final approach with full flap in the Warrior.

Anyone who tells you otherwise is misinformed. This is a classic example of old wives tales infiltrating correct practice.

Good luck!! Hopefully you can soon change your username to Greaseandgo.:)

[FormationFlyer]

There is a difference between approach speed & Vat.

On the pa28 75kts is the typical approach speed, however Vat is 63kts (everyone I know uses 65kts) for a normal full flap landing.

I think the folks over in private flying have got confused between the two...

[slim_slag]

There is a difference between approach speed & Vat.

I think the folks over in private flying have got confused between the two...

I think the word "approach" was being used loosely, as it is in real life, but the discussion was definitely about the merits of crossing the threshold/numbers at >65 knts, and even at 75knts. cheers.

[FormationFlyer]

Ah. Thats where im going wrong.

You see I thought I was instructing real world students about real world aviation in the real world ;)

Obviously I misunderstood.... :D

Seriously, 'approach' and 'threshold' speed are two different things - for instance you dont fly 63kts full flap on the 'initial approach' do you? no.

Now its not surprising that folks over in private flying have lapsed into shall we call it 'colloquial' language and thus get VERY VERY confused in the process. :confused:

As an instructor I will tell my student to set up 75kts as the approach speed for a visual circuit....turn base, carb ht hot, pwr 1500-1700, hold att - then as speed reaches 75kts set the descent attitude.

Thus when an instructor tells his student 'use 75kts as an approach speed' he means precisely that. Now if you ask him what speed should be used over the threshold youll get a different answer....for a pa28 typically 65kts for normal/glide and 70kts for flapless.....

Obviously I need to take off my rose tinted specs! ;) :D

On a genuine note - is there perhaps a difference in terminology used by instructors in the UK and those in the states regarding the terms 'approach speed' and 'threshold speed' - maybe this is where some of the confusion lies? :confused:

:)

[martinidoc]

I'm not sure how important it is to teach accurate adherence to the VAT speed. The important speed is the "approach speed". If this is correct, and the coordination of flare and throttle control is correct, VAT will fall into place. Once over the threshold I think it is more important to get the attitude correct than to be glued to the ASI to check whether you have 65 or 63Knots.

[Stiff Under Carriage]

Now its been a while since teaching on Warriors though from memory it went like this:

Turning base - PWR 1500-1700RPM, Carb Ht, 1st Stage flap; resulting in 80kts.
Turn Final - expected altitude given spacing 500'AGL
Mid Final - Second Stage Flap; Should have no need to touch power, speed should drop to 75kts.
Mid - Late Final - Full Flap, again shouldn't need to change PWR - airspeed reduces to 70kts.
Approaching Threshold - PWR reduces to idle slowly throughout flare to achieve idle at/just prior to, touchdown with Vref (Threshold speed) at 63-65kts.

Given conditions stable have a try to perfect but you'll find it works a charm.

Mind you this is from memory.

Good Luck

SU/C;)

[slim_slag]

ff

You want the Yanks to speak proper and use the Queen's English - again!! Them's fighting words :D

[FormationFlyer]

LOL! :)

No genuine curiosity as to whether or not there was a difference in terminology - Im not worried which is 'right or wrong' only whether or not there is a difference.

On the subject of approach speed if you are at 75kts and flare your speed will not drop off to 50kts by touchdown...the definition of Vat is speed over the threshold - to flare @ 75kts and touchdown at the correct speed you are looking at flaring @ 100'...however, unless I am mistaken Vat is defined @ 50' over the threshold (same as performance charts are calclated from). Thus you need to positively adjust to Vat rather than expect it to happen for you.

I will scan the ASI until the flare is started...I have 65kts pegged *before* commencing the flare. This leads to a touchdown speed in the 50kts region.

This is the way I was taught, this is the way I teach, it works for every approach...if you need 60kts for a short field approach you dont want to have 75kts at the start of the flare - you will take too much runway up...

Remember touchdown speed is once again different to threshold speed - there WILL be a deceleration from threshold speed to touchdown speed - it appears here that a touchdown speed of 65kts is being advocated! or did I misunderstand something? :confused:

As I said I aim for Vat *before* the flare...by the time the flare is complete hold-off is at a speed not far off of the stall...maybe 50-55kts.

The sequence I use/teach goes

Turn base , carb ht hot, set 1500-1700rpm, 2 stages of flap, hold att & let the airspeed reduce approaching 75kts lower the nose & trim.

Turn final, radio call, when short final full flap speed 65 kts.

Over the threshold start to reduce power & flare. Hold off (try to avoid landing - as I say to students - dont try and find the runway - its still there and will always find you! - pity the italian display pilot @ RAF Fairford this year hadnt been told this...)

If you are lucky the stall warner just went off as you touched down - failing that it should have been pretty close - i.e. speed of about 50kts (stall with full flap is 44kts).

Similar technique for short field - but peg 60kts - obviously requires playing the power now though...

This is a really interesting thread....Im curious for other comments...maybe one or two of the others here will wake up & chip in!!!! :D

[Chuck Ellsworth]

Hi FormationFlyer:

May I comment on one of your statements?

Quote " If you are at 75 kts. and flare your speed will not drop of to 50 kts. by touch down...."

That all depends on how you fly your airplane.

You can be at 175 kts and flare and given enough time and distance, by maintaining the proper attitudes without power, gravity and drag will decay your velocity ( speed ) and your airplane will drop to whatever airspeed it stalls at prior to runway contact.

The real secret is allowing all this to take place at the correct height above the runway during the decay of air speed especially when it stalls...6 inches above the runway at the stall is about perfect.

This is really not black magic or something beyond mere mortals being able to grasp, it is just plain old physics, aerodynamics and airplane handling. :D

I am sure you did not mean to state it the way you did. :)

Cat Driver:

[FormationFlyer]

True. hey - we are about

However, I dont teach my students to fly 75kts and then flare at 75kts from 150' or wherever...why? Because the manoeuvre you are talking about requires judgement....which they havent developed yet...

Illl bet at the threshold/50' you will be at Vat even if you start your flare from 175kts....you must be (well there abouts - depending on the 'type' of approach)...otherwise you wouldnt reach the runway in the same place at 6 inches just above the stall...

Im sure you will agree that flare height is governed by three things...sink rate, initial airspeed and target airspeed all types of landing follow that same principle - so we are entirely in agreement there.. :)

Examining it further - to end up landing at the same place @ the same speed means that you can only vary the point you start the flare at (for a given configuration)...and whatever happens you will fairly closely be at the same speed over the threshold.

Therefore what I am saying is if you dont place yourself over the threshold @ the right height at the right speed you will get a different performance.

If you take 2 identical aircraft - one over the threshold/50' @ 75kts and one at 65kts, the one at 75kts will land deeper for the same approach type and technique if they are to both have the same touchdown speed.

eek...hope folks can follow that....dont you agree?
:cool:

Regards

[slim_slag]

ff

So we have

Approach speed
final approach speed
missed approach speed
low approach speed
threshold approach speed
instrument approach procedure speed
approach speed demanded by tower because you have a 737 up your tail

any others?

[FormationFlyer]

:D LOL my friend!!!

Damnit. :eek: Forget the 737 one! Thanks for reminding me....

Oh yeah there is more...

Bar approach speed when paying for drinks
Bar approach speed when not paying for drinks

:D

[slim_slag]

:D :D

Yeh, and I have problems with approach speed towards minger in corner of same bar when chucking out time arrives and I'm feeling lonely. Just got learn to slow down!

Seems like it all depends on context. I find it hard to pay good money to climb away from the airfield at 79 knts, then have to pay good money to descend towards the airfield slower!!!! Approach at bottom of yellow arc speed sounds more like it :) :)