Flapless Approaches Options

[AirbusA380]

Why is the pitch attitude slightly higher during such a procedure? Is it to prevent accumulation of excessing airspeed due to less drag from no flaps, or it is to maintain a higher AoA due to the smaller wing surface area?

[Piltdown Man]

The AoA relates to the relative airflow and the chord line. Lowering flap means that the chord line has moved (you increased the incidence) and to maintain the same AoA, you have to lower the nose.

PM

[cessnapilot72]

The increased AoA also increases drag, which aids in slowing the aircraft down on approach.

Flapless approaches are a fine balance between a whole lot of factors!

[Piltdown Man]

"The increased AoA also increases drag, which aids in slowing the aircraft down on approach." Only if you are flying slower than minimum drag which judging by most flapless approaches I've seen is the most unlikely. Now I'll guess some numbers: PA28 & C172 approx 65 kts. So unless you are approaching at a speed significantly less than that, the drag won't be that great. However, come in faster than that (as I normally see) and as you reduce speed, you reduce your drag - making life even more difficult! And how about this - come in below min drag, and then if you accelerate, you reduce your drag! Eeerrrrgg!

PM

[dash8q300]

Wouldn't the pilot have to pitch down to see the runway!? If you're flying with a nose up pitch how are you supposed to tell where you are going? Perhaps if the aircraft had an ILS or autoland system you wouldn't need to look outside. That can still be a danger issue if you can't see your surroundings properly and other aircraft directly ahead of you.

Dash,

[Aspiring Boeing ...]

Well wouldnt a flapless aproach mean more airspeed to keep the a/c in the air, thus meaning more breaking power/ more runway length in which to stop?

Regards,
Chris

[Piltdown Man]

Flapless approaches in a C172 require approximately 10 knots more than a flapped one (8 kts plus 1/3rd) - not a lot really. And yes there is more intertia and it is important to remember that this is the product of mass x speed squared. Looking out shouldn't be a problem, because if you are not big enough to see out you are not big enough to fly that type. But have you two above ever wondered why this procedure is practiced? And what speed do you reckon that a flapless approach should be done at?

PM

[dash8q300]

Flapless approaches in a C172 require approximately 10 knots more than a flapped one (8 kts plus 1/3rd) - not a lot really. And yes there is more intertia and it is important to remember that this is the product of mass x speed squared. Looking out shouldn't be a problem, because if you are not big enough to see out you are not big enough to fly that type. But have you two above ever wondered why this procedure is practiced? And what speed do you reckon that a flapless approach should be done at?

PM

How stupid of me! It's not like pilots frequently do flapless landings. They would practice this procedure for emergencies, like the flap motor or hydrolics not working or perhaps a water landing in a low wing aircraft?
As for the speed they land at I would have no idea. A 747 has a landing speed of about 140kts, so I'm guessing maybe 180-200kts without flaps?? I don't know.

I am just learning all this stuff so please excuse me when I come out with weird or stupid comments

Dash,

[Aspiring Boeing ...]

Well i know a 747 weighing its "normal" landing weight lands at about 160/170 tks. (when i say normal i mean with max pax and 20,000lbs fuel left) Without flaps your probably talking at least 210kts, maybe more. I know the 737 landing speed is between 120 and 150kts depending on weight.

Regards,
Chris

[Piltdown Man]

How about sticking to bug smashers before you start leaping into the big stuff? Even on my small little plane, the approach speed varies by 45 knots (lowest approach speed approx. 113 Kts) depending on wind, weight and flap setting. Flying flapless would add just a measely 15 kts and makes the whole thing a non-event. So the larger aircraft have too great a speed range to make any "guessing" worthwhile and also somewhat pointless eg. your guesses for a normal landing already have a 30 knot difference. So stick with C172 and PA28 figures. These can be found quite easily.

PM

[trijetflyermd11]

Well i know a 747 weighing its "normal" landing weight lands at about 160/170 tks. (when i say normal i mean with max pax and 20,000lbs fuel left) Without flaps your probably talking at least 210kts, maybe more. I know the 737 landing speed is between 120 and 150kts depending on weight.

Regards,
Chris

The B747 speeds for normal landing are in the range of 130-145 kts. Size doesn´t really matter if it comes to approach speeds. The A380 for instance lands under normal conditions at around speeds of 130-140 kts. It part of the designers´ job to build a plane that can land at the slowest speeds possible. The 210 kts you mentioned are on the very high side. Most tires have a max tire speed of around 200-205 kts. The concord had a special set of tires with higher max. tire speeds. You´re right on if it comes to B737 speeds. The 150kts though are usually after adding a few knots for strong wind or gust compensation.