Michael Ash
2008-12-08 17:21:59 UTC
Fate never misses an opportunity to show me that I still have things to
learn, it seems!
I went out to fly my glider again yesterday. The forecast showed quite
strong winds, with 15-20kts on the surface and increasing sharply with
altitude, straight perpendicular to our local ridge, which meant good
ridge and possibly wave lift.
Got to the airport and assembled. The wind was doing this weird on and off
thing. For a few minutes I was tempted to use my one-man rigging aid
(which rolls around too much in a wind to use it on a day like that)
because it was just a dead calm behind the hangar. And then it started
blowing very strong and I was glad I didn't give in to temptation. Instead
I recruited a helper to carry the wings out and put them on directly. They
are heavy! But I was pleased with how quickly I was able to get them
attached, since I've only done it a few times before. It's a nice
advantage of having something a little more modern, they tend to go
together much more easily than the older stuff.
I ended up being the first tow of the day. The tow pilot had taken a spin
on his own and said it was very bumpy, so I made sure to strap in tight. I
wanted him to tow me in front of the ridge but he didn't want to fly
directly over the top because that's where the bumps would be worse.
Instead he proposed that we fly parallel to the ridge (perpendicular to
the wind) until we got past the end, then turn towards it and deposit me
there.
We took off and it was quite a fight all the way. Normally on tow you want
to use very tiny control deflections to make miniscule corrections to keep
position. Yesterday I was using full deflections left and right, often
full left followed immediately by full right. There's something a bit
unnerving about having full stick and rudder in and still rolling in the
opposite direction. Much more so when tied to another airplane by 200ft of
rope and he's doing the same thing... sometimes in the opposite direction!
We fought it up past the end of the ridge where the turbulence was as
terrible as it ever was, and then turned 90 degrees into the wind to
approach the end. At this point it was like we had become a helicopter.
It felt like we had simply ceased to move. I figured the wind had to be at
least 30kts at that altitude (we were around 2500ft above the airport at
that point). I wanted to have some idea of what the wind was doing so I
checked my airspeed indicator to see if I could estimate by subtraction...
and discovered that it was reading zero. Crap! I verified that my
altimeter was working properly by talking with the tow pilot, but the
airspeed indicator stayed firmly on the peg.
(Later on I figured out that this failure was probably due to not
inserting the pitot-static tube in the tail all the way. This goes in when
assembling the glider, and it has two "stops" when inserting. If you're
absent-minded and only push it to the first stop, you'll see what I saw.)
I debated going back for a bit, but decided to press on. The failed ASI
would be most critical in landing and there was no reason to get to that
stage right away. I figured that the more I flew it around in the air the
better I'd be when it came to the landing.
Our progress was so slow that we were more than 4000ft above the airport
when I decided to release, still behind the ridge. But plenty of altitude
to get to it. I dove for it and arrived still very high. I found lift
*everywhere*, but it was still crazy turbulent even in front of the
mountains. It was probably coming off the next set of mountains another
12 miles or so upwind, but usually it gets much better when clear of the
near ridge. I was just getting pounded constantly, even at 4-5000ft well
above the mountains, and after a while it got tiresome.
Finally decided to head for home after I'd taken enough punishment. I flew
back over the airport and just let it come down on its own. Went through
the landing checklist. Flaps, better leave them neutral this time, I want
the extra speed. Undercarriage, down. Speed... well, that's going to be a
problem. Try to fly "fast". Airbrakes work, look for traffic and land the
plane.
Downwind leg went by in a flash with all that wind on the tail. Got abeam
the numbers and said to myself, "self, you'd better turn base real early
with all this wind". Turned early, found myself drifting downwind at a
crazy rate. Crabbed into it at a good angle. Decided I was getting low.
Pushed the spoilers in. Still low. Runway's rising on the canopy rapidly.
Spoilers closed and locked. Runway *still* rising. Better do something
fast. Aimed for it and shoved the nose down. Dove into ground effect and
below whatever it was that caused all this, and finally managed to cross
the threshold at about 6ft.
Never before had I been so glad to be on the ground. I sat in the cockpit
and closed my eyes for a few seconds before getting out and pushing off
the runway.
I was very close to not making the runway there. I thought that if I was
lucky I might have made the grass underrun. Unlucky, it could have been
very messy and expensive.
As usual there was a chain of events leading up to this that I wanted to
discuss:
0) Decision to fly. I'm putting this at 0 instead of 1 because I don't
think it was an error. It was a strong day but within my capabilities.
However I still want it on the list because it's clear to me that
challenging weather exacerbates other problems.
1) Mistake during assembly when inserting the pitot-static tube causing
ASI failure. I knew about the two "stops" when inserting but, presumably,
it slipped my mind. My inexperience with assembly certainly contributed
here.
2) Flew downwind too wide and turned base too late. I should have kept my
downwind closer in, although this was not critical. I should have turned
base no later than the end of the runway, but I actually waited another
couple hundred feet.
3) Flew too slowly in the pattern. This one is really speculative because,
as noted, my airspeed indicator didn't work. But my impression is that I
was too slow for the conditions when I turned final. I think this happened
because of the illusion of great speed with the tailwind on downwind.
And then, fortunately, I broke the chain with:
4) Reacted quickly and correctly by diving for the ground to increase
speed and escape from the sink or wind gradient that was making me come up
short.
#0, as I mentioned, I don't consider a mistake. However it left me in a
much less forgiving environment for the rest. None of the others would
have mattered on a calm day.
#1 was just foolishness. I think that, having made this mistake and
suffered the consequences, I won't do it again. However it may merit
special mention on the assembly checklist.
#2 was probably partly due to being out of practice with high winds (they
tend to come in the winter here, and so I've had little flying in such
high winds for the past 8 months or so), and partly due to to being too
focused on making a "nice" landing near the threshold. With 3000ft of
pavement and a minimum landing roll in these winds of probably 300ft or
less, there was simply no good reason not to turn very early and aim
partway down the runway.
#3 came from the failed ASI but also insufficient compensation for it. I
probably should have flown *really* fast, instead of just "faster" as I
thought I was doing. In a glider it's way easier to bleed off a bunch of
extra energy than it is to make up a shortfall!
#4 is a maneuver I'd heard about a lot but never had the occasion to use,
whether for practice or for real, before yesterday. I'm *very* glad I was
able to think on my feet fast enough to realize what I had to do and do
it.
In the end it worked out ok, and turned out to be one of those good
learning experiences which scares the crap out of you but doesn't break
anything or hurt anybody. As such, I want to learn as much as I can from
it, which is why I'm writing it up here. If it helps or simply entertains
some of the rest of you, so much the better!
learn, it seems!
I went out to fly my glider again yesterday. The forecast showed quite
strong winds, with 15-20kts on the surface and increasing sharply with
altitude, straight perpendicular to our local ridge, which meant good
ridge and possibly wave lift.
Got to the airport and assembled. The wind was doing this weird on and off
thing. For a few minutes I was tempted to use my one-man rigging aid
(which rolls around too much in a wind to use it on a day like that)
because it was just a dead calm behind the hangar. And then it started
blowing very strong and I was glad I didn't give in to temptation. Instead
I recruited a helper to carry the wings out and put them on directly. They
are heavy! But I was pleased with how quickly I was able to get them
attached, since I've only done it a few times before. It's a nice
advantage of having something a little more modern, they tend to go
together much more easily than the older stuff.
I ended up being the first tow of the day. The tow pilot had taken a spin
on his own and said it was very bumpy, so I made sure to strap in tight. I
wanted him to tow me in front of the ridge but he didn't want to fly
directly over the top because that's where the bumps would be worse.
Instead he proposed that we fly parallel to the ridge (perpendicular to
the wind) until we got past the end, then turn towards it and deposit me
there.
We took off and it was quite a fight all the way. Normally on tow you want
to use very tiny control deflections to make miniscule corrections to keep
position. Yesterday I was using full deflections left and right, often
full left followed immediately by full right. There's something a bit
unnerving about having full stick and rudder in and still rolling in the
opposite direction. Much more so when tied to another airplane by 200ft of
rope and he's doing the same thing... sometimes in the opposite direction!
We fought it up past the end of the ridge where the turbulence was as
terrible as it ever was, and then turned 90 degrees into the wind to
approach the end. At this point it was like we had become a helicopter.
It felt like we had simply ceased to move. I figured the wind had to be at
least 30kts at that altitude (we were around 2500ft above the airport at
that point). I wanted to have some idea of what the wind was doing so I
checked my airspeed indicator to see if I could estimate by subtraction...
and discovered that it was reading zero. Crap! I verified that my
altimeter was working properly by talking with the tow pilot, but the
airspeed indicator stayed firmly on the peg.
(Later on I figured out that this failure was probably due to not
inserting the pitot-static tube in the tail all the way. This goes in when
assembling the glider, and it has two "stops" when inserting. If you're
absent-minded and only push it to the first stop, you'll see what I saw.)
I debated going back for a bit, but decided to press on. The failed ASI
would be most critical in landing and there was no reason to get to that
stage right away. I figured that the more I flew it around in the air the
better I'd be when it came to the landing.
Our progress was so slow that we were more than 4000ft above the airport
when I decided to release, still behind the ridge. But plenty of altitude
to get to it. I dove for it and arrived still very high. I found lift
*everywhere*, but it was still crazy turbulent even in front of the
mountains. It was probably coming off the next set of mountains another
12 miles or so upwind, but usually it gets much better when clear of the
near ridge. I was just getting pounded constantly, even at 4-5000ft well
above the mountains, and after a while it got tiresome.
Finally decided to head for home after I'd taken enough punishment. I flew
back over the airport and just let it come down on its own. Went through
the landing checklist. Flaps, better leave them neutral this time, I want
the extra speed. Undercarriage, down. Speed... well, that's going to be a
problem. Try to fly "fast". Airbrakes work, look for traffic and land the
plane.
Downwind leg went by in a flash with all that wind on the tail. Got abeam
the numbers and said to myself, "self, you'd better turn base real early
with all this wind". Turned early, found myself drifting downwind at a
crazy rate. Crabbed into it at a good angle. Decided I was getting low.
Pushed the spoilers in. Still low. Runway's rising on the canopy rapidly.
Spoilers closed and locked. Runway *still* rising. Better do something
fast. Aimed for it and shoved the nose down. Dove into ground effect and
below whatever it was that caused all this, and finally managed to cross
the threshold at about 6ft.
Never before had I been so glad to be on the ground. I sat in the cockpit
and closed my eyes for a few seconds before getting out and pushing off
the runway.
I was very close to not making the runway there. I thought that if I was
lucky I might have made the grass underrun. Unlucky, it could have been
very messy and expensive.
As usual there was a chain of events leading up to this that I wanted to
discuss:
0) Decision to fly. I'm putting this at 0 instead of 1 because I don't
think it was an error. It was a strong day but within my capabilities.
However I still want it on the list because it's clear to me that
challenging weather exacerbates other problems.
1) Mistake during assembly when inserting the pitot-static tube causing
ASI failure. I knew about the two "stops" when inserting but, presumably,
it slipped my mind. My inexperience with assembly certainly contributed
here.
2) Flew downwind too wide and turned base too late. I should have kept my
downwind closer in, although this was not critical. I should have turned
base no later than the end of the runway, but I actually waited another
couple hundred feet.
3) Flew too slowly in the pattern. This one is really speculative because,
as noted, my airspeed indicator didn't work. But my impression is that I
was too slow for the conditions when I turned final. I think this happened
because of the illusion of great speed with the tailwind on downwind.
And then, fortunately, I broke the chain with:
4) Reacted quickly and correctly by diving for the ground to increase
speed and escape from the sink or wind gradient that was making me come up
short.
#0, as I mentioned, I don't consider a mistake. However it left me in a
much less forgiving environment for the rest. None of the others would
have mattered on a calm day.
#1 was just foolishness. I think that, having made this mistake and
suffered the consequences, I won't do it again. However it may merit
special mention on the assembly checklist.
#2 was probably partly due to being out of practice with high winds (they
tend to come in the winter here, and so I've had little flying in such
high winds for the past 8 months or so), and partly due to to being too
focused on making a "nice" landing near the threshold. With 3000ft of
pavement and a minimum landing roll in these winds of probably 300ft or
less, there was simply no good reason not to turn very early and aim
partway down the runway.
#3 came from the failed ASI but also insufficient compensation for it. I
probably should have flown *really* fast, instead of just "faster" as I
thought I was doing. In a glider it's way easier to bleed off a bunch of
extra energy than it is to make up a shortfall!
#4 is a maneuver I'd heard about a lot but never had the occasion to use,
whether for practice or for real, before yesterday. I'm *very* glad I was
able to think on my feet fast enough to realize what I had to do and do
it.
In the end it worked out ok, and turned out to be one of those good
learning experiences which scares the crap out of you but doesn't break
anything or hurt anybody. As such, I want to learn as much as I can from
it, which is why I'm writing it up here. If it helps or simply entertains
some of the rest of you, so much the better!
--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon