Flap deployment when?

[Vev]

I was taking the other day with friends and the question of when do we deploy our flaps during configuring for a landing.

 

One of the guys said that he often deploys flaps during his base turn, which is something I have never done and was warned by my instructor not to do some years ago when I learnt to fly... this fellow asked me why he shouldn't deploy flaps in a turn and quite frankly I didn't have a qualified answer... whilst a few people in the discussion made comments, I don't think we cracked it.

 

What do you guys think?

 

Cheers

 

Vev

 

 

[Tomo]

Are we just talking Jabiru aircraft?

 

In most Jab's I pull on first stage on base, so after the turn. Also in the faster J230's if you pull power back, roll around onto base, the turn washes the speed off just nicely into the white arc for flap extension, well that's what I've discovered anyway.

 

In the Cessna's first stage of flap is often deployed on late downwind before turning base.

 

Can't help with flap deployment during the turn... as I don't think I've ever done it. Or even thought about it before!

 

I'm most interested to hear from the experienced, or those in the know, also :thumb_up:

 

 

[Gnarly Gnu]

For me 1st stage when turning base... one instructor requires just prior to turn, another prefers during the turn (more GA style I believe). I do the latter as the turn helps to wash off some speed so by mid turn on they go. 2nd stage on short final in normal circumstances i.e. unless there is significant cross wind or if the approach is a little low etc. Don't know about deploying mid base or later, I guess your circuit would be a little faster.

 

 

[facthunter]

. When an aircraft pitches up, as flaps are extended, (and the majority do) it can be very smooth to extend them as you roll into the turn. This reduces the need for back stick force and washes the speed off . Ab-inbitio pilots may do otherwise as you don't want to overload the early trainee, by doing too many things at once, but it can avoid unnecessary trim and power change on the approach. Nev

 

 

[Bandit12]

I would also agree that in the early stages, it might be asking a new pilot to multitask a little too much. I usually go to first stage of flap in the turn to base as well.

 

 

[Ultralights]

is there any rule as to when flap should be deployed? eg, in a forced landing where you only deploy flap once you know you can make the field, apart from that, well, for me it depends on a lot of factors, weather, runway length, approach. apart from the mentioned forced landing scenario, i base my flap setting on the windsock, and use it as a rough guide, windsock down, then full flap, windsock horizontal, flap up. though thinking about it, i mostly deploy flap on finals, either early or late. . if im going for a short field, with good approach terrain, then ill get 1 stage out on late base to get everything settled, then final stage on early final, set power and attitude and control everything on the throttle.(much like the 3.3deg airline approach). steep glide approach or ugly terrain under the approach (such as water or suburbia). well, flap on late final. or if i have a nice long runway, and steepish approach, i will often use no flap. short runway and steep approach, then full flap. so many variables its not really worth selecting one point. as for my students for the sake of simplicity in their early stages, flap on base, then final flap position on final depending on windsock. but as they progress towards licence and XC, then ill get them to see the use of flap as another flight control at your disposal and use it as required to achieve what you want. my most common aim though is glide approach every time, and flap on mid to short final mainly to move aiming point.

 

 

[Spin]

I was originally taught (in GA) to extend during the turn and as facthunter pointed out, it is helpful to prevent the usual attitude change during deployment. It is a subject which some instructors have strong feelings about and I've also been subject to a finger wagging lecture on the subject. I always get a bit of a grin when instructors thump the table about this sort of thing, knowing full well that other, equally qualified people teach the opposite.

 

 

[Yenn]

As required bythe current circumstances, or in my case never as I don't have flaps.

 

 

[eightyknots]

. When an aircraft pitches up, as flaps are extended, (and the majority do) it can be very smooth to extend them as you roll into the turn. This reduces the need for back stick force and washes the speed off . Ab-inbitio pilots may do otherwise as you don't want to overload the early trainee, by doing too many things at once, but it can avoid unnecessary trim and power change on the approach. Nev

 

is there any rule as to when flap should be deployed? eg, in a forced landing where you only deploy flap once you know you can make the field, apart from that, well, for me it depends on a lot of factors, weather, runway length, approach. apart from the mentioned forced landing scenario, i base my flap setting on the windsock, and use it as a rough guide, windsock down, then full flap, windsock horizontal, flap up. though thinking about it, i mostly deploy flap on finals, either early or late. . if im going for a short field, with good approach terrain, then ill get 1 stage out on late base to get everything settled, then final stage on early final, set power and attitude and control everything on the throttle.(much like the 3.3deg airline approach). steep glide approach or ugly terrain under the approach (such as water or suburbia). well, flap on late final. or if i have a nice long runway, and steepish approach, i will often use no flap. short runway and steep approach, then full flap. so many variables its not really worth selecting one point. as for my students for the sake of simplicity in their early stages, flap on base, then final flap position on final depending on windsock. but as they progress towards licence and XC, then ill get them to see the use of flap as another flight control at your disposal and use it as required to achieve what you want. my most common aim though is glide approach every time, and flap on mid to short final mainly to move aiming point.

Both very good answers: I have learned a lot from this. The only problem is that the aircraft I am training in (a Piper Super Cub) has no flaps for me to try this out on.

 

 

[Chris Tarran]

I was taught glide approaches and the process was throttle off at the end of downwind, allow speed to bleed off to the white arc and then extend flaps (to T/O) prior to the turn to base. If doing a short field approach I put out full flaps after turning final. This is in a Tecnam J2002 Sierra.

 

 

[sfGnome]

I was taught glide approaches and the process was throttle off at the end of downwind, allow speed to bleed off to the white arc and then extend flaps (to T/O) prior to the turn to base. If doing a short field approach I put out full flaps after turning final. This is in a Tecnam J2002 Sierra.

Interesting. I was taught the same, and it's never even occurred to me to do it differently. Having read this discussion, I'll have to have a bit of a play next time I'm up...

 

 

[foxy]

I like the idea of putting the first stage of flap out after im on base, and have the aircraft set up at its base speed....in my 170, its 70knts on base, then trim for the pressure. Then once the flaps come down, even with forward pressure on the control column, i dont move the trim. If the trim is still 'nose up' for that previous 70 knts, u dont have to fight against the trim during the flare..... My 2 cents...... :D

 

 

[Guest Jake.f]

I have been taught to go for one stage during base at some point, then set up for 55kts. Never had to use two stages with the massive runways here.

 

 

[jerrajerra]

I'm taught 1st stage of flap on base, 2nd and if required 3rd stage on final.

 

 

[pudestcon]

I'm feeling deprived; never flown a plane with flaps!!

 

Pud

 

 

[Vev]

Hi Guys,

 

Thanks for the input and the interesting discussion.

 

By the sounds of it, there is no dangerous effects from deploying flaps in the turn?

 

Cheers

 

Vev

 

 

[winsor68]

I have found with the Savanah you very rarely require the second stage of flap... its as Ultralights says, flaps are an extra glide path control, and I find the Sav nicer/easier to land with one stage. Of course if you were wanting to pull up nice and short and really use the capabilities of the aircraft you would use full flap but this is something that I will approach with time and caution (stol ops).

 

I deploy flaps during or just after the base leg turn and trim... second stage as required.

 

 

[Deskpilot]

Any time, even in the turn, PROVIDED your speed is below 72Knts. (Jab LSA55). Whatever aircraft you fly, if you're going to deploy flaps, only do it after you've bled off your speed. I hate to think what would happen if one flap broke and was left thrashing around and hanging buy one hinge only.

 

 

[motzartmerv]

I think the term "flaps as required" is lost on a lot of people. Sure a routine is whats needed when learning a basic approach, but I would encourage pilots to develop a "sence" for when more or less flap is required. I like Ultralights use of the windsock to help, however winds aloft can often be quite different to on the ground. Slippery types need exellent judgment of when and how much flap should be deployed and some instructors don't like useing power against flap, so early deployment which requires power to get you to the keys is looked down upon (by some) while other GA orientated instructors insist on forcing the "power as required" situation.

 

I would say that if conditions required you to deploy flap in the turn then by all means do it, I can't see anything inherently dangerous about it other than the distraction.

 

Talk to your instructor about the pro's and cons for your type.

 

cheers

 

 

[jerrajerra]

I follow a particular guy on youtube training at Moorabin (C172) and in it he deploys flaps on the turn and levels out to circuit height (1000ft) on commencement of downwind. Same AC, different training, different instructors/institutions. But generally an interesting read on what everyone does how why what functions are applicable depending on AC.

 

 

[Guernsey]

I'm feeling deprived; never flown a plane with flaps!! Pud

That's a good thing Pud, so there's no need to get in a flap about it.

Alan.

 

 

[Guernsey]

This particular thread is another one of those fantastic reasons for being a member of this forum.

 

I was always taught (GA) to turn base, slow down, apply first stage of flap then apply more flap as required on finals and do not apply flap during a turn.

 

Having flown many aircraft both with and without flaps over the years I find that like some others have stated that I am now reviewing my set ways regarding approaches with flaps. I now intend to broaden my thinking and try some of the methods mentioned. Thanks guys for your inputs.

 

Alan.

 

 

[facthunter]

The function of flaps is to add drag, provide the same lift at a lower speed and allow a better view over the nose. There is not much case for flying the full length of downwind in a normal aircraft with flap out, though on some types with the more efficient Fowler flaps the drag at small angles is not too great On faster types you would extend flaps to allow a lower safe manoeuvering speed, otherwise you could be around 230 knots.

 

Some aircraft ( like the Technam) have a flap extend speed very close to the minimum clean manoeuver speed in rough air and care should be taken to not exceed the permitted flap speed. Your airframe life and reliability are adversely affected by any overloading over the stipulated speeds, weights or turbulence or dynamic loading. Assymetric flap has been mentioned and it is well to bear in mind that when you are extending flap, be very aware of any tendency to roll caused by the flap extension. I doubt if many aircraft would be controllable in roll by the ailerons if a full flap assymetry is experienced so rudder might be applied as well and the flaps attempt to be restored to symmetry by retraction if that is appropriate. Nev

 

 

[winsor68]

Of thread but here is a thought... I extend flaps on the Sav at or below 55knots... if the whole circuit was flown with half flaps could you get a LP endorsement in this aircraft (I got HP- I guess it just gets over the line for it).

 

 

[68volksy]

In the Warrior I was taught first stage of flap as part of downwind checks. Second stage after the turn to base and after decreasing throttle. Then set for 80 knots (which i've found is pretty much impossible to miss with revs at 1800rpm and almost full forward trim). Third stage after turning final with full forward trim and you're sitting on 70 knots at 1800rpm. This pretty much has me hitting the threshold (still working on smoothing out that flare...) in anything up to about 15 knots headwind with only minor adjustments to pitch/power.

 

Warrior flaps deploy at around 100kts so extending on downwind doesn't affect things too much. Teraya and Mike always seem to throw in some distraction or other to mess all this up though and get me out of the comfort zone which I suppose is a good thing...