Sunday, January 07, 2007

I don't know much about this clip except that it's a glider, and the landing doesn't seem to go very well.

5 comments:

aluwings said...

re: your comment about the landing not going well - at first I was thinking the same, but after watching it a second time, I think it was a normal, grass field landing with a rollout ending up right where the pilot wanted it (off the side near the glider trailers/parking).

Jim Howard said...

How many gliders have a CDI?

Aviatrix said...

Yeah, remember that gliders don't really have landing gear, just one wheel in the middle under the cockpit and a tail skid, so that once rudder efectiveness is loss, there is no steering on the ground.

The pilot says in the air "not much wind today" but turning final the trees appear whiter than they did before. It's hard to tell in a video, but I suspect it is because the wind is blowing directly towards the trees we see, inverting the leaves to the lighter undersides. A small light aircraft landing downwind is going to float a lot further than otherwise.

I've only landed in a glider twice, but I don't recall the "rollout" being as long as this one, adding to my suspicion that the landing groundspeed was higher than normal.

Too bad the pilot isn't here to defend himself.

nec Timide said...

Yes, I would have like know a little more detail. There may be some tailwind, but more important factors are the left cross component and the fact that he seems very hot. The 'CVR' is not very clear but he says "90 degree flaps all the way". In a glider the lift control devices (flaps, spoilers, dive breaks) provide glide slope control the same way the trottle does in a powered airplane.

He keeps moving his hand from the flap lever to assist with the stick, this is bad technique and almost costs him pilot induced oscillation as he enters the flare. The right wing goes down and is dragging and he has full right rudder for at least part of the ground run but the glider continues to weathercock left probably due to a left crosswind component. There is rather more wing dragging than is generally desired. Training gliders have outriggers with springs, more advanced machines get by with skid pads, either way dragging the wing loads the spar and attachment fittings.

Watch the yaw string (on the pitot head in the centre of the canopy) during the turn to turns to base and final for evidence of poor rudder control. I think this was an instructional flight where the instructor let things go far enough to be impressive during the debreif. The aggressive check back, check forward looks like the "hand of god" preventing a carrier style arrival.

All that said, a go around is not an option in a glider, you have to do your best with the cards you're dealt and how well or badly you've played them to that point. It could have gone much worse, but didn't and sometimes that is enough.

Soaring Student said...

That glider landing was a bit rough, but not nasty.

There was some yaw as he was heading into the circuit, and I was surprised that the landing was performed with no spoilers (half spoilers are the norm, so you can either extend the glide or accelerate the rate of descent). But you see the lack of spoilers in the nose-down attitude during the approach.

The roll-out looked normal enough - it looked like he was trying to extend the roll-out to get to the hanger area (otherwise you've got a bunch of tugging an towing to do).

Usually, pulling the spoilers back to to full extension also engages the brake, and I note that spoilers were not pulled fully back, which is why I figured the long rollout was intended.

In a glider the airlerons (and the rudder) are effective at an amazingly low speed - you can keep a wing up at running speed. Similarly, I've just kicked the rudder at the end of a runout and veered off the runway.

I agree on the positioning of the hands.. one should be on the spoiler, on on the stick, throughout the landing sequence. You don't and accidental full spoiler deployment 50' AGL and short of the runway (normally you'll glide for another 1000' feet before touchdown - and that's in a low-performance glider).