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If I want reduce the landing roll distance, for example to clear the runway at the nearest exit, I was told by some instructors that to increase the drag using following methods:

  1. Pull up and hold the elevator at the upper extreme position.

Question 1: does that mean I should try to keep the nose wheel in air as long as possible?Is there any risk I leave the ground again due to aggressive pitch? Will there be any effect after all the wheels touched the ground, like keep the elevator up can increase the friction of the main wheels?

  1. Retract flap to reduce the lift to create more frictions.

Questions 2: when flap is retracted, I will have less lift so more friction force could be induced but does that mean the aircraft is in a cleaner config, so the drag is also reduced?

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  • $\begingroup$ see aero braking aviation.stackexchange.com/questions/51834/… $\endgroup$ – Pilothead Dec 18 '19 at 8:21
  • $\begingroup$ My experience shows that full flap deflection (the opposite of retracted) increase drag dramatically, especially on short final. Spoilers may be best suited to decrease lift. $\endgroup$ – Manu H Dec 18 '19 at 9:21
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    $\begingroup$ You didn't specify what aircraft you are talking to but brakes are the most effective way to stop in the shortest distance. $\endgroup$ – wbeard52 Dec 19 '19 at 15:16
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    $\begingroup$ @wbeard52: Not always true. Brakes aren't nearly as effective on dirt or grass (especially grass wet from dew or recent rain) as they are on pavement. And they're less effective on wet or snowy/icy pavement than dry. $\endgroup$ – jamesqf Dec 19 '19 at 18:44
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1) This does mean you should keep the nose up as long as possible, increasing the angle of attack when you are behind the drag curve increases the drag the wing produces and uses the elevator as a spoiler in effect. If you have done a full stall landing pulling up cannot get you back into the air, but if you land with extra speed pulling up could mean you start flying again, so you should only use this technique if you are sure you have a low enough airspeed. Good technique is not to yank the stick back, you pull it back while paying attention to the "feel" of the airplane, if it seems to want to fly again ease off on the back pressure.

2) Retracting flap after landing decreases lift and puts more weight on the wheels, making the wheel brakes more effective. It does decrease drag, however your wheel brakes are much more effective at slowing the airplane than drag from the flaps.

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You didn't specify what type of aircraft you are asking about. I will tell what I learned during my micro-light flight training (probably partially applicable to smaller General Aviation planes aswell).

For a tricycle landing gears you are supposed to land with the nosewheel up, since the landing gear is quite "flimsy" on micro-lights. So breaking while the nose is up introduces a forward momentum, which can bring your nose down quite hard, risking damage to your nosewheel and a prop strike. After flaring out you keep the elevator pulled usually but at some point the nosewheel comes down by itself and you can break safely.

In STOL competitions you see many taildraggers hitting the breaks hard, as soon as they touch down. There the breaking has to be controlled very well, to not get a prop strike.

For airliners in general it is a bit different (massive landing gear, good runway condition). I think as soon as the spoilers come up the airflow is disrupted and the lift component of the flaps is reduced (negligible). There was one famous landing of a stripped down IL-62 (called "Lady Agnes") landing on a 900m grass field, where right after touching down with all three wheels, they got the nose back up to use the whole wing as an airbrake and the extended spoilers to keep the main landing gear down for breaking. The flaps staid extended during the whole landing and rollout.

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