ATR 42 and 72 - aerodynamics during landing

[Stuck_in_an_ATR]

I've been flying both the 72 and 42-500 for some time and found the 42 much more forgiving during landing. The 72 seems very prone to balooning and it's is easy to to flare high. On the other hand, the 42 seems to land quite nicely by itself almost everytime - one just has to be careful with the power levers...

Can anyone explain me why those two similar planes behave differently? My theory is that the 72 has longer wingspan than the 42, thus higher aspect ratio and steeper lift curve - i.e a change in the AoA produces higher lift change, which leads to ballooning. Also, the 72 has a lower landing flap setting so is less draggy during flare (though it falls like a brick with PL's retarded too much). Am I right, or off track here?

[Kit d'Rection KG]

Try thinking about the fuselage length and empennage...

[Kit d'Rection KG]

PS... If your trainers haven't explained all of this to you, they should have done.

[Aussie]

Some things can be missed or forgotten....

Aussie

[Stuck_in_an_ATR]

PS... If your trainers haven't explained all of this to you, they should have done.

Seems they haven't... Perhaps you can rectify their neglect? :8

I know different length of fuselage means different moment arm of the stabilizer, which affects controlability and stability. I know I may expect the 72 to behave differently form the 42, but I still don't know EXACTLY what makes the 72 trickier to land than the 42 - hence my question....

[error_401]

Trying to figure that myself.
But the simple answer might be: "The 72 is a different aircraft".
Different wing. Different lenght. Different empennage. Different speeds.
Depends on the models if you are flying the 42-300 and 72-200 also different prop rpm settings which makes a huge difference.
The 72 still tricky to land with a tendancy to skip on landing. (Those gentle skips where the main landing gear is just unloaded). Flare a little too much and you get a float. In high winds or crosswind I use props at 100 % rpm for approach and landing. Gives better results and avoids floats and skips as the characteristics are closer to the 42.
Have fun

[aeroconejo]

OK.....ATR training skipper here......

While the 72 is effectively a 'stretch' of the 42 it does handle noticeably differently in certain phases of flight. It is (obviously) larger, has more power and different aerodynamic characteristics to the 42.

The landing technique is basically to keep some power on until you get to around 10 ft on the rad alt and then close the power levers and flare considerably less than you do in a 42 (which isn't much anyway). Some of my colleagues say 'just drive it on'.

Hope this helps

aero

[Stuck_in_an_ATR]

Thanks for input! - I've been flying the type for almost 3 years and it's not that I have any problem landing the 72 (o.k. - I foul it up from time to time:}). Just trying to figure out what makes the 72 behave like it does... As one of my trainers said - "the 42 is an airplane, while the 72 is just a machine to carry people" :)

[AHRS]

Thanks for raising the issue old chap!
I read your quote with interest.I have flown the ATR42 but not the 72.I have also flown various types of jet transport on 6 axis simulators(Trident 3e,Tristar,Challenger,Hawker 800) as well PC pretty much most jet transport from Concorde,747-4,707,767,777,A340-5/6.

Based on my real flying experience from the ATR 42 and quoting from my PC simulated experience(and I assure a lot can be learnt from these models)-especially between the handling quality differences between same type with different fuselage lengths e.g A340-500/600:I can present my views for which I invite any valuable critique.First however, I prefer to entitle the subject as a FLIGHT CONTROL issue rather than an aerodynamic one(although that is the net effect).

1) I believe when attempting to produce a standard landing performance, the FCOM should take precedence in providing the basic guide and to improvise as the situation dictates in your best judgement to execute an acceptabe landing.Problems arise when obsession with smooth landings dominate the hand to eye coordination and recommended practices are ditched in the process.So first take a look at the difference in the FCOM between the ATR42 AND 72 at say 50 and below-with respect to power management and target pitch attitude..and above all keeping perspective of the sink rate at that point(radio height calls are valuable for providing such cues.A glance at the IVSI at 50 FT SHOULD GIVE YOU A QUICK CLUE AS TO THE TREND AND CORRECTIVE MAGNITUDE REQUIRED).The IVSI IS A PRIMARY CONTROL INSTRUMENT AND INVALUABLE DURING FLARE,HOWEVER, IS DOES NOT GET THE ATTENTION IT FREQUENTLY DESERVES FOR THIS PHASE!i MEAN WHAT CONTROLS A GOOD LANDING(ASSUMING YOU ARE IN THE SLOT AND ARE DUE TO ALND ON THE TOUCH DOWN ZONE)?..THE SINK RATE!

2)The longer fuselage and more rear main wheels position of the ATR72 should have you gain a different perspective for the "seat of the pants flare feel".Because the wheel height on both these aircraft being similarly low..i imagine it feels/imaginarily pronouncedly lower on the ATR 72 due to geometrical differences and thus instictively prompts you to want to flare a little prematurely and thus higher(extra for mother mentality) it is a psychological issue.The longer fuselage will generally require a slightly less target flare pitch attitude.This target pitch attitude like on any aircraft can be observed and should in the long run be part of your subconscious.

3)An additional factor to consider is the higher landing speed of the 72.Come a little excess of it and float/balloon...all the aspects of an unstabilised flare will prevail...and the rest is familiar.....
The 72 is a heavier and bigger machine and should be treated closer to medium jet transport handling thinking..it will require earlier stability on the approach and little tinkering on the flare, if you are "in the slot"

4)Finally, the landing flare on a longer fuselage type such as is the difference between the 42 and 72 would require a slightly lower pitch demand and even lower pitch rate demand(flare inputs should be smoother to effect a less turning moments about the CG.Knowing the expected CG(nose or tail heavy) can help with what kind and amount of flare input you should require.ALL THIS SHOULD BE DONE SUBCONSCIOUSLY OFCOURSE, BUT YOU HAVE TO BE AWARE OF THE SITUATION IN THE FIRST PLACE.It should take place on your "personal approach briefing".

5)Seat position/pilot-eye height should not be discounted either...do callibrate the seat position against those white and orange balls as suggested by the FCOM.

Finally, if this flare control issue is a common fleet feature then it should be addressed to ATR and have their test pilots review the FCOM.

Need I add more?


I've been flying both the 72 and 42-500 for some time and found the 42 much more forgiving during landing. The 72 seems very prone to balooning and it's is easy to to flare high. On the other hand, the 42 seems to land quite nicely by itself almost everytime - one just has to be careful with the power levers...

Can anyone explain me why those two similar planes behave differently? My theory is that the 72 has longer wingspan than the 42, thus higher aspect ratio and steeper lift curve - i.e a change in the AoA produces higher lift change, which leads to ballooning. Also, the 72 has a lower landing flap setting so is less draggy during flare (though it falls like a brick with PL's retarded too much). Am I right, or off track here?

[Clandestino]

Need I add more?:=
I'm afraid not, sir. The techniques you described might very well work with Microsoft Flight Simulator but are slightly incompatible with real flying. Your notions of IVSI being primary instrument in flare or that ATR72 should be treated like medium jet are a bit unrealistic.

[AHRS]

Absolutely not, sir. The techniques you described might very well work with Microsoft Flight Simulator but are not compatible with real flying. Your notions of IVSI being primary instrument in flare or that ATR72 should be treated like medium jet are a bit unrealistic, to say the least. I'd suggest that your ideas could get better acceptance on some MSFS fans forum than here.

If I had meant them to be for MFSM I would have very well suggested so.I think if you read more carefully you will have noted that I actually have flown the ATR42 and was a master at that.

I admit to perhaps incorrectly used the word primary instrument on the IVSI sounded a little too focused and it shouldn't be, but I assume you are already in side the flare(you have selected the target pitch attitude at the right height(which in the case of the ATR42 was 20ft)...and to most certainly include the IVSI in the scan for it will, if you dont already feel the sink or hear the frequency of radio height calls,provide you a trend check.

The ATR72 every one knows is not a Turbo fan, but the momentum and size differences compared to the ATR42 and relative to smal to medium jets like Fokker 80/100 should require a little more diligence than it deserves as a turbo prop.I have not flown the ATR72 and so if your opinion is qualified you may critique this.

OtherwiseYour abrasive opinions should best be kept to yourself I suggest.You are welcome to prove me wrong..but prove me you must instead of relegating me to the world of Microsoft, which I have experienced additional to my real flying (as you put it) since 1988.Got my "real" licenses in 1990......MORE COMMENTS??

[click]

Having flown the 42 and the 72 and NOT a master may I add a few cents worth?:} Selecting a target pitch attitude and having your eyeballs inside the cockpit below 50' is.......rather shall I say it? Ok, queer. Both machines are great for the short hops inside a couple of hours, the 72 balloons a lot so you gotta drive her on. We had several versions of the 42. The 320, 400 and 500. The 500 finally has some balls and increased gross weight so you can actually take fuel and people as well. Aeroconejo is right, the 72 has to be landed flat or you'll end up with racing stripes up your butt, the 42 is like a big Cessna 172, chop the throttle at flare, bring the nose up and land like you've been taught:ok: .

[ICING AOA]

my rule is the following:

"only real pilots can land the ATR72 properly, the remaining pilots are just crap" :ok: :cool:



speaking about the 72, did anyone here knew that there are some new emergency doors ? check this pic !

http://www.planepictures.net/netshow.php?id=565369

[AHRS]

I was driving a similar message mate(unless you wanna misquote people without digesting what they write first)...if you read closely.You land it with a shallower pitch.If your scan is disciplined , there are no rules to say you can't scan/glance both in and out...nothing queer about that, just dextrous mate.Even during the flare you are notsupposed to fixate on any parameter...Perhaps you should try and see what improvements that leads to.It doesn't take much guts to glance at the IVSI whilst landing an airplane I assure you!If you declare yourself NOT as a master of your job, then I pity you and will have to take your comments lacking in substance. Ballooning generaly is seen as a pilot induced probem and not aircraft induced..airworthiness authorities would otherwise see to it that a remedial measure is taken.

Having flown the 42 and the 72 and NOT a master may I add a few cents worth?:} Selecting a target pitch attitude and having your eyeballs inside the cockpit below 50' is.......rather shall I say it? Ok, queer. Both machines are great for the short hops inside a couple of hours, the 72 balloons a lot so you gotta drive her on. We had several versions of the 42. The 320, 400 and 500. The 500 finally has some balls and increased gross weight so you can actually take fuel and people as well. Aeroconejo is right, the 72 has to be landed flat or you'll end up with racing stripes up your butt, the 42 is like a big Cessna 172, chop the throttle at flare, bring the nose up and land like you've been taught:ok: .

[AHRS]

Thanks for your self assured comments.Ever tried landing a 17t ATR42 on an african short bush airstrip surrounded with obstacles in rain with non other than a remotely placed ndb for guidance?What makes a pilot real as per your definition?

my rule is the following:

"only real pilots can land the ATR72 properly, the remaining pilots are just crap" :ok: :cool:



speaking about the 72, did anyone here knew that there are some new emergency doors ? check this pic !

http://www.planepictures.net/netshow.php?id=565369

[Clandestino]

My appologies to the master of ATR-42, I havent recognized that your generous employer has equipped your 42 with IVSIs. Since they have to have something to be driven by, I'd like to know: how many IRSes were on your ATR? Two or was there a third standby? Perhaps they were not mere IRSes but ADIRS or even GNADIRS units?
F-ATCS (on which I've accrued 98 hrs, far too much for my liking) definitevely had plain ADC driven VSIs and their usefulness during flare, should someone be so foolish as to check them then, was zero or below. Watching the people chasing the green arc during RA reversals was not much fun either. Especially during CLIMB, CLIMB NOW as altimeters would already start winding up quite quickly, while VSIs would still insist we're descending.

[kulkma]

Does any one know what is the Eye to Wheel height for ATR 72-600 please?

[Twomonthsoff]

Coming from an experienced TP captain who is current, the ATR72 is a dog of an aeroplane; handles poorly, insufficient power especially when it comes to icing conditions; you must get your flare/hold off correct, keep it at about 5deg during landing, much more ie 8 and you will scrape your butt! Lo bank hi bank etc etc, IMHO, it’s way too complex for us simple pilots. It’s an accountants aeroplane, burns average 630-680 ph where I operate (ISA +15) which is v good. I am most definitely not saying in any way that it’s unsafe but this type requires care and attention through all phases of flight and as far as I’m concerned, of all the types I’ve operated, my least favourite. And one more thing, ATR attempting to improve things with their shiny multi screened 600; just doesn’t work for me, it’s still just an underpowered 72 that’s frankly no good for the hotter climates. 42-500 is a very capable machine; I operated this in the tropics too with very high LSALT’s; a pilots machine much more so than the 72; if you’re down a donk, it will keep you out of trouble!

If you’re not convinced, why do Aussie TP operators prefer the Q400; it simply performs under those conditions

[Twomonthsoff]

Spot on #7