Landing with reduced airbrake

On Monday, May 14, 2018 at 10:30:05 PM UTC-5, Richard McLean wrote:
Hi again flubber,

I just re-read (most of!) that thread .. an I do remember it now.

It doesn't really address my question which is (to paraphrase):

In gliders with a low angle of attack 2 point attitude (e.g. DG-1001 & LS8)

does anyone else find that trying to land with lots of airbrake inevitable

results in a tail-strike, and therefore reducing the airbrake to (let's
say) 1/2
at around 100 ft or so is advsed?

I'm not sure why the concern for a tail-first touchdown. Unless you snatch the stick back at the last moment, or are really slow and stalled and basically falling, a tailwheel first touchdown (when fully held off with low descent rate) is not going to hurt the plane - and guarantees the lowest touchdown speed and no bounce, if that is the goal, by rotating the wing to a lower AOA when the tail touches.

I try for the tail to touch first when I land my LS6, and at most it touches just before the main. Really hard to get that tail down further!

That being said, if going into a really short field, I want a good sink rate and the tail touching first for a really short landing run. You can burn off a bit of energy by a firm touchdown (just don't get carried away!)

If you have the luxury of easing off the brakes on final, then you are going for style points instead of landing distance, and it's more a matter of how much brake you like out when you flare and land. But not a good idea to be sawing on the airbrakes on short final!

Cheers

Kirk
66

On Tuesday, 15 May 2018 12:13:46 UTC+8, kirk.stant wrote:
On Monday, May 14, 2018 at 10:30:05 PM UTC-5, Richard McLean wrote:
Hi again flubber,

I just re-read (most of!) that thread .. an I do remember it now.

It doesn't really address my question which is (to paraphrase):

In gliders with a low angle of attack 2 point attitude (e.g. DG-1001 & LS8)

does anyone else find that trying to land with lots of airbrake inevitable

results in a tail-strike, and therefore reducing the airbrake to (let's
say) 1/2
at around 100 ft or so is advsed?

I'm not sure why the concern for a tail-first touchdown. Unless you snatch the stick back at the last moment, or are really slow and stalled and basically falling, a tailwheel first touchdown (when fully held off with low descent rate) is not going to hurt the plane - and guarantees the lowest touchdown speed and no bounce, if that is the goal, by rotating the wing to a lower AOA when the tail touches.

I try for the tail to touch first when I land my LS6, and at most it touches just before the main. Really hard to get that tail down further!

That being said, if going into a really short field, I want a good sink rate and the tail touching first for a really short landing run. You can burn off a bit of energy by a firm touchdown (just don't get carried away!)

If you have the luxury of easing off the brakes on final, then you are going for style points instead of landing distance, and it's more a matter of how much brake you like out when you flare and land. But not a good idea to be sawing on the airbrakes on short final!

Cheers

Kirk
66

Gday Kirk,

The concern is that students are breaking tailwheels in our DG-1001. The latest one probably form a loss of energy after a higher than optimal flare.

We have an old DG-1000 with a much higher 2 point nose attitude and it hasn't been an issue in 10 years or so .. but our brand-new DG-1001 (with nosewheel & much lower main wheel) has a much lower 2 point attitude which means that with a high rate of descent e.g. full brake and/or too slow the glider can touch down heavily on the tailwheel & it bursts.

One suggestion was that we limit the rate of descent for students by getting them to reduce airbrakes prior to the landing - even if they are still overshooting. A very experienced pilot suggested reducing the airbrake (if it's full for an overshoot) at around 100 ft to moderate the rate of descent and help prevent the tail-strike described. His theory is that some gliders with a small 2 point attitude are more prone to this.

Cheers,

Richard