Tom Knauff's newsletter

I'm extremely happy to see the text in parenthesis on point no.3. I have
called attention to this to the Soaring Safety Foundation. In coaching a
new tow pilot (I am not one) he made his first couple of attempts at this
at a somewhat slow but vigorous rate. The result was a large yaw and the
Pawnee with its large dihedral looked almost like rocking the wings.

At 18:35 02 July 2008, Uncle Fuzzy wrote:
On Jul 2, 10:12=A0am, George Knight wrote:
Yes, =A0I'd like to know what the third one is!

At 02:33 02 July 2008, Mike Schumann wrote:If you really want to help
edu=
cate the pilots that need it, why not

include what the signals are in your post!





Mike Schumann- Hide quoted text -

- Show quoted text -

1. Tow plane Wing rock - release immediately
2. Tow plane yawing back and forth - towplane unable to release rope
3. Tow plane rudder waggle (too quickly to significantly yaw the
airplane) - check glider for extended spoilers.

On Jul 1, 8:26*pm, "Bill Daniels" bildan@comcast-dot-net wrote:
Q#3: *Any uniform green color indicates a growing crop. *This could be
alfalfa, corn or something else. *You can land in freshly cut alfalfa or hay
but not much else. *Green usually means some form of irrigation which adds
additional hazards like sprinkler pipes. *Landing in a crop is likely to
cause some irritation among the farm folk. *Dirt, if it's reasonably smooth,
level and large enough, is always landable. *(Answer: C)

I agree with most of that but it may be too simple an answer. You need
to know what crop is grown in the area you are flying and how tall it
is likely to be at that particular time of year. You also need to
know how it is watered or irrigated. Landings in siphon irrigated
cotton fields, that are common in Arizona, can be made safely with no
crop damage if you are able to keep both wheels in the same furrow and
if the cotton is still short. On the other hand I know of a glider
that sufferered significant fuselage damage on landing in a recently
plowed field. The dirt clods were as hard as concrete and up to a
foot across.

Of all the landouts I have made I think the best field surfaces were
mown alfapha and wheat stubble. One of the worst was a fallow dirt
field that was so soft it was almost impossible to roll the glider to
the trailer as it sank six inches deep in powder. Nice short landing
roll though!

So I don't know what answer Tom wanted to that question. My answer
would be to make a choice based on size, slope, surface and a
knowledge of local crop conditions. The best choice could be either
green or brown but I'd take a look at the brown one first and hope it
had a thermal.

You can see why I don't like multiple choice tests

Andy

Andy wrote:
I agree with most of that but it may be too simple an answer. You need
to know what crop is grown in the area you are flying and how tall it
is likely to be at that particular time of year. You also need to
know how it is watered or irrigated. Landings in siphon irrigated
cotton fields, that are common in Arizona, can be made safely with no
crop damage if you are able to keep both wheels in the same furrow and
if the cotton is still short. On the other hand I know of a glider
that sufferered significant fuselage damage on landing in a recently
plowed field. The dirt clods were as hard as concrete and up to a
foot across.

Wow - does this mean I need to get an endorsement for agricultural science
on my certificate before I solo, or just before attempting a cross country?
;-)

"Jim Logajan" wrote in message
.. .
Andy wrote:
I agree with most of that but it may be too simple an answer. You need
to know what crop is grown in the area you are flying and how tall it
is likely to be at that particular time of year. You also need to
know how it is watered or irrigated. Landings in siphon irrigated
cotton fields, that are common in Arizona, can be made safely with no
crop damage if you are able to keep both wheels in the same furrow and
if the cotton is still short. On the other hand I know of a glider
that sufferered significant fuselage damage on landing in a recently
plowed field. The dirt clods were as hard as concrete and up to a
foot across.

Wow - does this mean I need to get an endorsement for agricultural science
on my certificate before I solo, or just before attempting a cross
country?
;-)

Wouldn't hurt.

I agree with what Andy wrote. A freshly cut crop like a wheat stubble field
is a great runway. Fallow wheat fields are nice too.

Wheat stubble is usually brown, however, not green. Uncut wheat looks
almost the same until you are low enough to see the "waves of grain" and
then it may be too late to pick something else. If you land in standing
wheat, close the air vents. I didn't and got a very upset hornet in the
cockpit with me.

Big, hard clods in a plowed field are a problem for gear doors if not more.

On Wed, 02 Jul 2008 18:13:30 -0600, Bill Daniels wrote:


"Jim Logajan" wrote in message
Wow - does this mean I need to get an endorsement for agricultural science
on my certificate before I solo, or just before attempting a cross
country?
;-)

Wouldn't hurt.

Agreed.

As an easier alternative, the information in this site may also be useful
outside the UK:

http://www.field-landings.co.uk/

I think the paired air-ground pictures (click 'CROP IMAGES') should be
useful almost anywhere round the world if you translate the time of year
to suit your seasons.


--
martin@ | Martin Gregorie
gregorie. |
org | Zappa fan & glider pilot

At 03:26 02 July 2008, Bill Daniels wrote:

Examples of the questions include:

snip

During a steep, continuous left hand turn, how are the controls held?

A. Left Aileron, right rudder, back stick
B. Left aileron, left rudder, back stick
C. Right aileron, right rudder, back stick
D. Right aileron, left rudder, back stick


Q#2: This one needs a some qualification since it depends on the glider.

Obviously, into-the-turn aileron (left in a left turn) would never be
used

in a continuous turn so the choice is between C and D.

I find many gliders, once stabilized in a turn, will track nicely with
the

string centered with my feet off the pedals indicating no rudder is
needed

at all. Only opposite aileron (right in this case) is used to hold off
the
overbanking tendency - this right aileron provides all the left yaw
(adverse
yaw) needed to center the string. Gliders with less adverse yaw will
need

some into-the-turn rudder (Answer: D). Gliders with a lot of adverse
yaw

may need a little out-of-the-turn rudder (right) (Answer: C).

One must add that the Dick Johnson technique of using a slight slip also

works nicely and adds a little to the performance. Dick holds
out-of-the-turn rudder to oppose overbanking and keeps the stick
centered.

In my experience, this works best on gliders with generous dihedral and
without winglets or polyhedral.

snip

Bill Daniels

I notice from the back seat in a left turn that the yaw string for the
front cockpit is slightly more to the right than the one in the back; I
believe this to be because the front one is farther from the center of
lift -- or the tangent of the turning radius.

This leads me to believe that the rudder, also displaced from the center
of lift would likely align itself with its own relative wind and would
thus be slightly to the left if unattended.

I do not think of this as holding bottom rudder. I was taught to hold a
little top rudder and it might just be that a bit of pressure on the top
rudder would place it somewhere between the place it would naturally seek
and perfect alignment with the fuselage if not actually to the outside.

I do note that if the nose drifts too low in a turn it is much easier to
move it back to the proper position by applying top rudder than it is to
add more back pressure on the stick. I believe this is also much safer --
a little bit of slip instead of lowering the airspeed with the stick while
holding top aileron and bottom rudder, the classic setup for spin entry.

React, Bill?

Nyal Williams wrote:

I notice from the back seat in a left turn that the yaw string for the
front cockpit is slightly more to the right than the one in the back; I
believe this to be because the front one is farther from the center of
lift -- or the tangent of the turning radius.


I suspect not. Assuming the following: 1. on a 2 seater, the front yaw
string is about 6 ft (2m) ahead of the center of lift. 2. According to
the American Soaring handbook, a 45 degree banked turn at 60 mph (52
kts) has a radius of 240 feet (73m).

High school level geometry and trigonometry (I've been out of high
school for a looong time :-) ) shows that this results in an error of
only 1.4 degrees - small enough to be ignored for all practical purposes.

I suspect that a yaw string, typically taped to the canopy, may have
errors because the string is in the boundary layer.

Tony V.

I suspect that a yaw string, typically taped to the canopy, may have
errors because the string is in the boundary layer.

Tony V.

Closer than the OP, but still doesn't seem quite right. The front yaw
string is much more subject to 'crossflow effect' (on most ships) than
the back one due to canopy shape and the string's relative placement
on a compound curve that is sometimes splitting air striking it
(besides, both strings are in the boundary layer...)
With this in mind, it is not a bad idea to "calibrate" ones yawstring
by comparing it's position relative to a panel mounted slip-skid ball
when flying a new ship, perhaps even marking the coordinated positions
(at 45 deg banks?) with pinstripe tape if they are far off center.
Jonson also covers this in the previously mentioned article about
mildly slipping during thermalling turns (named "Circling the
Holighaus Way" http://www.owp.us/Johnson/CirclingTheHolighausWay.pdf
). He explains it much more elegantly than I and it is worth reading
if you have not already seen it.

-Paul

sisu1a wrote:

With this in mind, it is not a bad idea to "calibrate" ones yawstring
by comparing it's position relative to a panel mounted slip-skid ball....

But the 2 instruments measure different things. The yawstring (in
theory) measures airflow angle at the fuselage. The inclinometer
measures the difference between gravity and the opposite centripetal
force - when in balance, the ball is centered.

The question is, which is a better measure of coordination? Or, IOW,
which is more important? Because of the difference in drag at the
wingtips during the turn, the nose may yaw away from the center of the
turn. The yaw string would show that, while at the same time, the
inclinometer would be centered. I understand that some believe that
that's the way it should be. Others believe that you need to hold rudder
into the turn to minimize the drag.

I should experiment in my LS6. Lord knows that I'm tired of looking up
at the gaggle :-).

Tony V.

Martin Gregorie wrote:
As an easier alternative, the information in this site may also be
useful outside the UK:

http://www.field-landings.co.uk/

I think the paired air-ground pictures (click 'CROP IMAGES') should be
useful almost anywhere round the world if you translate the time of
year to suit your seasons.

Thanks for link - I've bookmarked it for futurer reference.