Being towed too slow?

[Steve Leonard]

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

[Hal[_2_]]

On Nov 16, 8:44 pm, 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

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.

[John Smith]

Steve Leonard wrote:

> have your radio call be 'Towplane pulling
> Glider (Insert your callsign here), please speed up

Even better would be to know the callsign of your tow plane. I consider
a short radio check with my tug before taking off a basic safety rule, YMMV.

[Ian]

On 17 Nov, 04:44, Steve Leonard >
wrote:

> Or better yet, spend a little time talking with the
> towpilots and getting to know them.

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.

Ian

[[email protected]]

Hi Folks,

I'm new to this list.
I'm the towpilot at Great Western Soaring in Crystalire which is in
the Mojave desert, right up by the mountains, in California.
Come and see us, you can find us on the web.

Tow speed is always an issue.

I have found very often, when glider pilots complain of incorrect
speeds, it is because their AIS are not working properly.

Yes it is a good idea to communicate with the towpilot, but how many
glider 'renters' have their own radios??

Les H


On Nov 16, 8:44 pm, 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

[[email protected]]

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

[Ian]

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

Our ... whats?

Ian

[Marc Ramsey[_2_]]

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

Fred, I assume you've worked some contests (which is what this
discussion is primarily about), you know what it's like. You can't just
amble over and talk to the tow pilot prior to each launch, nor are you
supposed to even do a radio check. You get hooked up and go, and if you
have any issue with that, you go to the back of the grid.

That said, I've had tow pilots I know quite well (with a tow slip that
clearly says I want 65 knots), yank and bank at 50 knots while I'm still
rolling on the ground in the Duo with a passenger. Even tow pilots have
bad days, and despite some assurances to the contrary, many heavy
gliders are bears to handle on tow at 50 knots...

Marc

[Mike Lindsay]

In article
s.com>, Ian > writes
>On 17 Nov, 04:44, Steve Leonard >
>wrote:
>
>> Or better yet, spend a little time talking with the
>> towpilots and getting to know them.
>
>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.
>
>Ian

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.
--
Mike Lindsay

[Shawn[_4_]]

Ian wrote:
> On 17 Nov, 16:55, wrote:
>> Hey, glider pilots, go back to your FARs
>
> Our ... whats?

F@ckin' American Rules :-)


Shawn

[J a c k[_2_]]

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

[Ian]

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

[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

[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

[Shawn[_4_]]

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

[play]

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

[5Z]

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

[[email protected]]

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"

[Ben]

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/wikipedia/commons/f/fe/Airplane_vortex_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/about/Organizations/Technology/Facts/TF-2004-02-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?

[John Smith]

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.

[Mike Lindsay]

In article >, Ben <
>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.
>
Er, yes. I think you have got this a bit wrong.

We have to do an exercise in our annual check called "boxing the wake".

One of the objects is to show you where the turbulence behind the tug
is. You fly out to one side, go lower and lower, still out to the side,
then gradually fly to a position behind the tug but below the wake. It
never stops surprising me how far below the tug you have to be to be
clear of the turbulence.

This is a bit unpleasant for the tuggie, who has to use a bootfull of
rudder to keep straight.

In the normal, high tow position we use, the tug appears about a wing
span or a wingspan and a half above the horizon, and the air in that
position is usually pretty quiet.

So it looks to me as if the disturbed air is deflected downwards,
probably about 20 degrees. Which is what you'd expect from the way a
wing works. The plane in the picture was just taking off, not in free
air, so not really comparable.

As to gaining energy from the upgoing bit of the tugs wingtip vortices,
I'll bet you a pizza that the increased drag your rudder would produce
to fly in that position would more than compensate for any advantage
you'd get.

>http://upload.wikimedia.org/wikipedia/commons/f/fe/Airplane_vortex_edit.jpg

--
Mike Lindsay

[Ben]

Mike Lindsay wrote:
> In article >, Ben <
>
>>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.
>>
>
> Er, yes. I think you have got this a bit wrong.
>

> So it looks to me as if the disturbed air is deflected downwards,
> probably about 20 degrees. Which is what you'd expect from the way a
> wing works. The plane in the picture was just taking off, not in free
> air, so not really comparable.
>
> As to gaining energy from the upgoing bit of the tugs wingtip vortices,
> I'll bet you a pizza that the increased drag your rudder would produce
> to fly in that position would more than compensate for any advantage
> you'd get.
>
>
>>http://upload.wikimedia.org/wikipedia/commons/f/fe/Airplane_vortex_edit.jpg
>
>

It looks like in this wind tunnel picture that the airflow is deflected
downward even at quite a distance above the wing.

http://www.jefflewis.net/graphics/aircraft/aerodesign_P0001845.html


It seems like even in
high tow you might still be in an airstream that is deflected downward
significantly compared to the airstream that the towplane is feeling.
I was speculating to myself that with a glider like a 1-26 or 2-33, you
don't really notice the problem, since your stall speed is so low
relative to the towplane, but when a heavily ballasted glider with a
stall speed in the mid to high 40kt range gets towed by a towplane with
a stall speed in the low 50kt range, you're starting to get where
perhaps that downward component of the airstream that the glider is
flying in compared to what the towplane is flying in becomes
significant, and the glider may come close to flying in a near stalled
condition even though the towplane is still happy as a clam. Has
there been any actual scientific wind tunnel data published on the
towplane - glider configuration to actually analyze this in a systematic
way as opposed to the valuable, yet still anecdotal, opinions expressed
so far on the thread? I was wondering if any of the Akafliegs had
studied this but couldn't find anything on a Google search. I did see
one study by NASA on a 747 towplane - towing a proposed freighter
glider but you had to order it, so i didn't read it.

On the subject of trying to gain energy from the towplane's wingtip
vortices, I saw a video of a goose flying formation with an ultralight
trike where the goose was flying just in front of the trike's wing and
not flapping at all, getting a free ride from the upward
deflected air in front of the wing. Could this be used by advanced
students of leeching technology? The other example might be Dr.
MacCready's little hand tossed glider you could push along with the air
deflected by your hands. Perhaps when getting towed, we have the
opposite problem, since we are usually flying in the downwash from both
wingtip vortices of the towplane, we lose energy rather than gain it. I
was thinking maybe if you hold some bank relative to the towplane,
rather than using rudder to get out to the side, and perhaps with a CG
hook rather than a nose hook, it might not create as much drag to fly
out to the side and get in the upward part of the wingtip vortex and
perhaps get a boost. Somebody should do some real scientific tests on
this. Is Dick Johnson listening?

[Ben]

>I was wondering if any of the Akafliegs had
>studied this but couldn't find anything on a Google search. I did see
>one study by NASA on a 747 towplane - towing a proposed freighter
>glider but you had to order it, so i didn't read it.

Apologies for the above, I found some pretty relavent links by searching
on Formation Flight Aerodyamics, so I'm sure it's all been worked out.
But maybe not as well analysed yet for the particular problem of a heavy
glider on tow.

[Martin Gregorie[_1_]]

Ben wrote:
>
> It looks like in this wind tunnel picture that the airflow is deflected
> downward even at quite a distance above the wing.
>
> http://www.jefflewis.net/graphics/aircraft/aerodesign_P0001845.html
>
> It seems like even in
> high tow you might still be in an airstream that is deflected downward
> significantly compared to the airstream that the towplane is feeling.
>
The other thing it shows is that, to keep a normal AOA on tow, you'll be
pitched up further than in free gliding flight.

If you hit PREV a few times in that sequence there's a nice head-on view
of smoke tracing the tip vortex. The top of the vortex slopes slightly
down as it travels rearward, so away from the ground there is no
significant upward flow behind the top plane's tip as somebody else
suggested.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |