The East River turn

I have a question for this group, but first must state (as will soon
become obvious) that I'm not a pilot and know just enough about flying
to be dangerous, i.e., not much. The question: I've read on this
newsgroup that the turn that Lidle's plane was making was tight (I'm
very familiar with this territory -- my parents lived on 64th and 1st
for 30 years) and that the radius of a turn varies directly with the
square of the airspeed. So, too fast, and you might swing too wide. Too
slow, and you risk stalling (a very bad thing at such low altitudes, I
would think). Couldn't you lower the flaps prior to entering the turn,
to lower your stall speed and thus permit a lower airspeed and a
tighter turn? If this is not a stupid question and is feasible, how
would lowering the flaps interact with a crosswind from the east, as
apparently was the case on Wednesday? Would the lowered flaps make the
plane more sensitive to what would be a tailwind as it was turning,
blowing it more toward Manhattan, negating (somewhat or completely) the
point of the lower airspeed?

/Don Allen

wrote:
I have a question for this group, but first must state (as will soon
become obvious) that I'm not a pilot and know just enough about flying
to be dangerous, i.e., not much. The question: I've read on this
newsgroup that the turn that Lidle's plane was making was tight (I'm
very familiar with this territory -- my parents lived on 64th and 1st
for 30 years) and that the radius of a turn varies directly with the
square of the airspeed. So, too fast, and you might swing too wide. Too
slow, and you risk stalling (a very bad thing at such low altitudes, I
would think). Couldn't you lower the flaps prior to entering the turn,
to lower your stall speed and thus permit a lower airspeed and a
tighter turn? If this is not a stupid question and is feasible, how
would lowering the flaps interact with a crosswind from the east, as
apparently was the case on Wednesday? Would the lowered flaps make the
plane more sensitive to what would be a tailwind as it was turning,
blowing it more toward Manhattan, negating (somewhat or completely) the
point of the lower airspeed?

/Don Allen

Not a stupid question at all. However, if the plane was going too fast
(not sure what flap speed is on the SR20) it'd have to reduce power and
slow down before lowering any flap. The problem here is time. It seems
as if they essentially flew into a box canyon and had to make the 180
turn quickly before busting LaGuardia's airspace so the turn was
probably made at something nearer to cruise speed which would mean a
larger turning radius and prohibit flaps.

wrote:
Couldn't you lower the flaps prior to entering the turn, to lower your
stall speed and thus permit a lower airspeed and a tighter turn?

Yes, you could. This, of course, assumes that you had done some pre-flight
planning and knew this was what you were going to need to do.

If this is not a stupid question and is feasible, how
would lowering the flaps interact with a crosswind

If you know the airspeed and bank angle, you can compute two related
numbers: turn radius and rate of turn. To figure out how the aircraft is
affected by a crosswind, the easiest thing to look at is rate of turn.

A "standard rate" turn takes 1 minute to do a 180 heading change. That's a
pretty slow turn and is usually only used in instrument flying. In visual
conditions, you would normally be flying turns several times that rate.
Lets assume for the moment it'll take us 20 seconds to make a 180 degree
turn. Let's further assume there's a 10 knot crosswind. 10 knots is about
17 feet per second. So, in 20 seconds, the wind will blow us 17*20 = 340
feet.

If we use flaps to let us fly slower, we'll not only be making a smaller
radius turn, but we'll also have a higher rate of turn, the crosswind will
have less of an effect.
`

In my Cessna 185 the smallest radius turn is pretty much like this. Slow
down, full flaps, at stall warning 45 degree bank, full power.

It will go around remarkably tight.

Karl
"Curator" N185KG

"Kingfish" wrote in message
ps.com...
Not a stupid question at all. However, if the plane was going too fast
(not sure what flap speed is on the SR20) it'd have to reduce power and
slow down before lowering any flap. The problem here is time. It seems
as if they essentially flew into a box canyon and had to make the 180
turn quickly before busting LaGuardia's airspace so the turn was
probably made at something nearer to cruise speed which would mean a
larger turning radius and prohibit flaps.

The radar track showed they were going at 97 knots. At that speed, turning
with a 50-degree bank should've worked fine, with no need for flaps.

--Gary

"Gary Drescher" wrote in message
...
"Kingfish" wrote in message
ps.com...
Not a stupid question at all. However, if the plane was going too fast
(not sure what flap speed is on the SR20) it'd have to reduce power and
slow down before lowering any flap. The problem here is time. It seems
as if they essentially flew into a box canyon and had to make the 180
turn quickly before busting LaGuardia's airspace so the turn was
probably made at something nearer to cruise speed which would mean a
larger turning radius and prohibit flaps.

The radar track showed they were going at 97 knots. At that speed, turning
with a 50-degree bank should've worked fine, with no need for flaps.

--Gary


Did it show whether they started in the middle, or well off to one side?

Any Idea what the winds were that day?

I hate to ask it, but did they turn "downwind"? (See, I didn't actually
say "downwind turn")

Al G

It looked like he started about 2/3 of the way across to the east. A little
bit farther east and a little bit slower and it probably wouldn't have been
a problem.

mike

"Al G" wrote in message
...

"Gary Drescher" wrote in message
...
"Kingfish" wrote in message
ps.com...
Not a stupid question at all. However, if the plane was going too fast
(not sure what flap speed is on the SR20) it'd have to reduce power and
slow down before lowering any flap. The problem here is time. It seems
as if they essentially flew into a box canyon and had to make the 180
turn quickly before busting LaGuardia's airspace so the turn was
probably made at something nearer to cruise speed which would mean a
larger turning radius and prohibit flaps.

The radar track showed they were going at 97 knots. At that speed,
turning with a 50-degree bank should've worked fine, with no need for
flaps.

--Gary


Did it show whether they started in the middle, or well off to one
side?

Any Idea what the winds were that day?

I hate to ask it, but did they turn "downwind"? (See, I didn't
actually say "downwind turn")

Al G