Being towed too slow?

Ian wrote:

I tend to have the opposite problem - tug pilots may not tow much
wood, and often go rather fast. So whenever I can, I make a point of
talking to the tuggy beforehand and letting them know my ideal speed
range.


I've had the same problem in a 1-26. At 75 MPH IAS the bird gets a
little more sensitive in pitch than I like on tow, so prior to departure
I have asked for a 65 MPH IAS max. 60 MPH IAS is not that easy for a
Pawnee to do, but just letting them know that it makes a big difference
to a 1-26 does help.


Jack

On 17 Nov, 20:48, Shawn wrote:
Ian wrote:
On 17 Nov, 16:55, wrote:
Hey, glider pilots, go back to your FARs

Our ... whats?

F@ckin' American Rules :-)

Ah. An equivalent of the Campaign Against Aviation, then? Or the Every
Action Stops Aviation lot ...

Ian

On 17 Nov, 19:31, Mike Lindsay wrote:

A lot of years ago I was towed at 80 KPH when the glider had a placard
reading Ne jamais depasser 65KPH. Nobody seemed the least bothered.

A lot of years ago I was given an aerotow retrieve in a Slingsby
Swallow by a tug pilot who was the CFI of a club which shall remain
nameless. Max aerotow speed: 61kt (or some pathetic number about
that). Actual tow speed: 90kt. And the Swallow was twitchy enough on
the elevator at the best of times. Still, I was poor(er) then, and the
CFI knew I was paying by the minute for the retrieve.

Ian

On 17 Nov, 21:49, J a c k wrote:
Ian wrote:
I tend to have the opposite problem - tug pilots may not tow much
wood, and often go rather fast. So whenever I can, I make a point of
talking to the tuggy beforehand and letting them know my ideal speed
range.

I've had the same problem in a 1-26. At 75 MPH IAS the bird gets a
little more sensitive in pitch than I like on tow, so prior to departure
I have asked for a 65 MPH IAS max. 60 MPH IAS is not that easy for a
Pawnee to do, but just letting them know that it makes a big difference
to a 1-26 does help.

My standard speed compromise with the Sutton Bank tuggy was to go up
with the CHT needles on the red line. Faster than I'd have liked,
slower than he'd have liked, but both reasonably happy!

Ian

Ian wrote:
On 17 Nov, 20:48, Shawn wrote:
Ian wrote:
On 17 Nov, 16:55, wrote:

Hey, glider pilots, go back to your FARs

Our ... whats?

F@ckin' American Rules :-)

Ah. An equivalent of the Campaign Against Aviation, then? Or the Every
Action Stops Aviation lot ...

That would be the Feds Against Aviation's (who's motto is "We're not
happy 'till you're not happy.") rule book.


Shawn

On Sat, 17 Nov 2007 13:48:43 -0700, Shawn wrote:

Ian wrote:
On 17 Nov, 16:55, wrote:
Hey, glider pilots, go back to your FARs

Our ... whats?

F@ckin' American Rules :-)


Shawn


I just snorted coffee all over my keyboard, thanks.... :-)

Peter

On Nov 16, 11:18 pm, Hal wrote:
On Nov 16, 8:44 pm, Steve Leonard
wrote:
If you are carrying water and the tow plane slows down below the stall
speed what would happen. I felt things were close once and used the
radio to request speeding up. Can't imagine rocking the wings when
you are in that situation.

Been there, done that. Unfortunately the &%#$% tow pilot was on a
different frequency. This was during a contest, so briefing & radio
check were implied, not done individually.

Had OK speed to about 500', then we started slowing down, and still
flying straight out, not yet on a crosswind. I'm in a fully loaded
ASW-20B. I immediately started asking for more speed, but no
response. I dropped through the wake with nearly full back elevator,
and stayed in low tow with stick against aft stop, ailerons feeling
like mush, so keeping wings as level as I could (actually, they were
rocking quite a bit) with rudder, and my left hand HOLDING the release
(no worries if I let go too soon) just in case I start spinning. Took
about 20 minutes to calm down while working the start gaggle after
release.

Why didn't I just release and get another tow? Well, although I was
quite worked up and not very happy, I was not in a safe position to
release at first, so I had to hang on at least for another 30-40
seconds. By then, since we were climbing, and I understood my
predicament, I was too busy dealing with a situation I now understood,
instead of creating a new one. So I decided I could calm down much
better in the sailplane in a thermal, than landing with water, on a
hot airport, pushing back to the launch line, yelling at the tow
pilot, etc, etc, etc.

-Tom

On Nov 17, 11:55 am, wrote:
Hey, glider pilots, go back to your FARs -- they require you to agree
with the tow pilot on four points before taking off: "airspeed
limitations, emergency procedures, signals, and maximum angles of
bank." (FAR 61.69). Some of this is standardized, so you don't have
to say you'll use specific signals, but speeds vary according to
ballasting, etc. So not only is it a good idea to talk to the tow
pilot, it is actually a requirement. When I'm towing I want to talk
to the glider pilot prior to hookup anyway so I know he has a working
radio and I know who will be billed. So to standardize, I like
towpilots to establish radio contact as you are being hooked up and
find out WHO the pilot is and Where he wants to go. A third item is
obviously the radio check, but if you've passed the name and
destination along, you've also established that your radio is
working. And this is the time to pass on your required tow speed.
Fred

Its all much too complicated.
I gave up on this getting towed business; much simpler now ;-)
See ya, Dave "YO"

Steve Leonard wrote:
Seems to be a common thing at contests or any other
time you are flying something different than what the
pilot is use to pulling. How about the next time it
happens to you, have your radio call be 'Towplane pulling
Glider (Insert your callsign here), please speed up
5 MPH' or some such if you aren't clearly able to identify
the towplane. Most of those guys know what glider
they are pulling at the time. They keep track so they
have a record of how many tows they made.

Or better yet, spend a little time talking with the
towpilots and getting to know them. When it is your
turn, watch and see who comes by to pull you into the
sky. If you are being pulled too slow or too fast,
call the towpilot by name with your request. But do
it very nicely, please. As John pointed out, these
guys work hard so we can go play. And sometimes, they
even get to go play, too.

Thanks again to all that have towed me!

Steve Leonard
Wichita, KS




I've been thinking about this and here is my simple minded non-expert,
but merely intuitive
explanation. Experts please tell me if I'm all wet.

Even though you are tied to the towplane and
get pulled along at what looks like from the ground to be the
same speed, the glider is actually experiencing a reduced indicated
airspeed and a relative wind at a different and unfavorable angle
compared to the towplane due to the disturbance to
the air from the towplane that the glider is flying through.
Check out this picture of what is happening to the air behind
an airplane not much bigger than many of our towplanes.

http://upload.wikimedia.org/wikipedi...ortex_edit.jpg

Anybody who has been in a sailboat race and in the wind shadow of
another sailboat and been "blanketed" will recognize the loss of energy
and sluggish
performance of his boat relative to the one ahead in the "clear air".
On tow, you're flying your glider between two large contrarotating
tornadoes right in the area of maximum downwash. Even in high tow, you
are still greatly affected by this downward component of the airflow
behind the
towplane, because the circulation extends well above the towplane's
wing. Relative to the angle of attack he is experiencing, at
the same tow speed, your effective angle of attack is not the same as
his, as
some of the air you are flying in behind him is actually being dragged
along in
the same direction as he is, so the indicated airspeed your glider feels
is less than what he feels. It's a bit like a continuous wind gradient.
The friction from the passage of the towplane causes the air to be
pulled along behind him and that's what your flying in.
Also there may also be some effects of being towed on longitudinal
and roll stability some of which were studied by NASA when towing an
QF-106 behind a C-141 Starlifter. Incidently, the Starlifter towplane
took off first at about 132 mph, while the QF-106 was still on the
ground. The QF-106 didn't lift off until they accelerated to 189 mph.
Maybe this same technique of towplane taking off first could be used at
some of the contests
to pull those really heavy gliders (only with good pre-flight
briefing between tow pilot and glider pilot, of course).

http://www.nasa.gov/centers/dryden/a...4-02-DFRC.html


Another interesting study involved some F-18's cruising in formation
in the upward part of the leader's vortexes and gaining as much as 100
mile of range by using that energy. Maybe if your glider is real heavy,
you should move way out to the side of the towplane, and try to get into
the upward going part of the vortex. You might be able to get some of
the opposite effects seen right behind the towplane where the downwash
is maximal. Has anyone ever experienced
a boost in glider tow behavior out to the side like that? Perhaps on
a double tow or something like that? Has anything like that been
formally studied and written up somewhere?

Ben wrote:

On tow, you're flying your glider between two large contrarotating
tornadoes right in the area of maximum downwash. Even in high tow, you

I know people who did the comparison themselves. Here's what they told
me: E.g. a Fox behind a "conventional" tug requires at least 65, better
70 knots to be safe. But the same Fox flyes perfectly happy at 55 knots
behind an ultra light (or very light or light sport or whatever it's
called in your country). I think this illustrates the effect of downwash
as well as any picture or NASA research.