high tow vs low tow

[Steve Koerner]

As a US pilot, I've flown low tow a few times but mostly just high tow as that is the convention here. I'm wondering what all of the trade-offs are by the two methods? Might it be time to reconsider this?

As pointed out on another thread, low tow would seem to be safer against the problem of glider kiting up to overpower the tugs up elevator. I'm wondering if it's ever possible for a low tow glider to go too low and overpower the tugs down elevator?

Also, how does low tow compare in the other common dangerous towing situation wherein the tug flys too slow for a highly ballasted glider? My own experience with a seriously too slow tug is that I end up falling to low tow whether I like it or not.

Has anyone done a lot of tows both ways and have reasons as to which way is better?

[John Foster]

The risk of the tow rope wrapping around the glider is higher if you have a rope break on low tow.

[BobW]

On 2/24/2019 8:27 PM, Steve Koerner wrote:
> As a US pilot, I've flown low tow a few times but mostly just high tow as
> that is the convention here. I'm wondering what all of the trade-offs are
> by the two methods? Might it be time to reconsider this?
>
> As pointed out on another thread, low tow would seem to be safer against
> the problem of glider kiting up to overpower the tugs up elevator. I'm
> wondering if it's ever possible for a low tow glider to go too low and
> overpower the tugs down elevator?

Having performed low tows only by way of demonstrating 'em during BFRs
(remember them?), the aerospace engineer in me has little doubt that 'all that
glider mass back there' *could* 'cause alarming things to happen to the tug'
if Joe Glider Pilot is either seriously asleep at the stick or intentionally
and unilaterally plays Joe Test Pilot.

That said, my visual take on low tow is that 'well before' a tug-upsetting low
tow position is likely to be reached, Joe Glider Pilot will almost certainly
find the visual picture so alarming that he'll take corrective action. Clearly
that's not the case with high tow...

So, OZ glider pilots, how do you folks manage to kill your tow pilots? Too
much beer? :)

Bob W.

---
This email has been checked for viruses by AVG.
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[JS]

(Other than landing on tow)
High tow makes the most sense to me, even in Australia.
Fly the glider!
Jim

[Charlie Quebec]

It only makes sense if you like towplane crashes. When a glider kites on high tow down low there is no time for the tow pilot to recover.
Had this been a low tow, the likely hood is very strong that the pilot would have survived. In Au, we only do low tow training, and I’ve never seen
any problems or even the slightest upset of the tow plane on low tow. Some years ago we used to go to high tow to release, but even that was scrapped.
It needs to be remembered that low tow means just below the slipstream. C of G hooks make high tow even more dangerous.

[Cookie]

High tow, low tow....

One of the (many) arguments in aviation that you just can't win.

I teach my students to be proficient at both.

The I give them my lecture, "when in Rome......."

-Cookie

[Charlie M. (UH & 002 owner/pilot)]

Since this topic comes up every few years, very diplomatic reply you posted Cookie.

Yes, in the US, high tow is the norm except for training demonstration/practice.

Our club is an exception, we have been doing low tow as the norm since I started flying some 45 years ago. We do teach high tow, I use high tow at other fields...."When in Rome...."
Others flying at our place are given the option of which to fly, we tell the towpilot if a high tow is to be expected.

[Tango Eight]

I realize that you come here chiefly to wind people up, but let's just set that aside for a moment.

If you have a shred of actual evidence for the relative safety of low tow, cite it. The guys who studied the problem and test flew upset scenarios at altitude don't agree with you.

Chris Rollings:

"The belief that low-tow significantly reduces the risk of sling-shot tug
upsets is mistaken. The trigger is if the glider pitches up to about 30
degrees above the line of the rope. Being in low-tow when that happens
simple makes the sunsequent event take about half a second longer - not
enough extra time to greatly increase the chance of releasing before the
critical point."

Critical point: it's the acceleration of the kiting glider that does the tow pilot in. The towplane is suddenly slowed, probably below 1g stall speed, accompanied by loss of elevator authority, then it's pitched over and put into a deep negative angle of attack. Take away: low tow doesn't and can't prevent this from happening. The glider pilot has the task of preventing this from happening. See figure 2 here https://members.gliding.co.uk/library/safety-briefings/safe-aerotowing-booklet/

Rope length is far more important to tow (in)stability than either tow position or hook location. Anyone can test. Try a 150' rope and a 225' rope. Difference is obvious and dramatic. In contrast, the difference between high and low tow is pretty subtle as far as control pressure goes and I honestly feel no difference in stability. We use 225' because it's the longest our tow pilots can safely manage on final approach (road crossing). I have on rare occasion towed on even longer ropes (275') and felt that was over doing things.

Nose vs CG hook is another myth. It would take a lot of work to assemble the data, but anecdotally we already know: the vast majority of tug upsets and upset/accidents involve nose hook equipped gliders. Most CG hook gliders (e.g. ASW-20s and such) tow very nicely.

T8

[Cookie]

Charlie M.

Regarding Valley Soaring...where low tow is used...

I avoid using the term "high tow" because over the years I've seen many pilots who interpret this as meaning to "fly above the tow plane"...I've done many an uneasy check ride where the pilot, thinking they were doing high tow, flew way above the tow plane...

Of course the term high tow, means to "fly above the wake", NEVER above the tow plane!
So I started using the terms .."low tow", and "normal tow"...but one of the Valley pilots aptly pointed out that low tow is "normal" for them!!!!

So now I have to teach my students what I call "below the wake" tow and "above the wake tow"

BTW...with the powerful tow planes we have at our field, which can climb quite steeply...above the wake, is actually quite a bit below the tow plane...

Conversely, on a cross country tow, when the tow plane is flying level, and the wash goes straight back...."low tow" (just below the wake) is not really all that low...(almost the same sight picture as above the wake in a steep climb!

Cookie

[uncl...@ix.netcom.com]

I've done something over 20,000 flights at both ends, 12k or so at the back and something over 8k at the front.
Properly flown, as high as possible without being in the wake, the glider is very closely aligned with the thrust line of the tug and has almost no effect on trim.
Flown too low, the glider pilot can have a poorer view of the horizon.
Being a bit high is obvious.
The rope wrapping hazard happens if there is slack caused by a fairly quick, big descent. I have never witnessed this happening in operations I have been involved with.
We tested the "pull the tail down" risk and could not accomplish it. The angles don't work. In trying this we had our Cub down to below 45 MPH with the glider behind hanging low. It was more stable with the glider on at that speed.
My experience is that low is easier to teach and do at the beginning because the view is a bit better and the wake is not anywhere near as much of an issue.
Get slack- Move to the side to take it out, just like high(normal?) tow.
Rope will hit the glider. Could happen if way too low when tug releases it. If the glider is in proper position when releasing the rope doesn't go much up or down. If the tug releases the rope drops below and behind and probably, but not surely back releases.
Rope will wrap around the glider- I have yet to figure out how a rope can go upwind against a 60 mph headwind.
The rope will scratch my belly when using a CG hook. No scratches on my ships in 40+ years of low tow.
Most training, from my experience, teaches pilots to fly too low.
If one wants to get better at this, a couple dual flights with an experienced instructor can be useful.
Also note that many tugs have mirrors set up such that the tow pilot can't see the glider in low tow.
Tell your tow pilot what you plan to do. Trim settings are different so he or she may want to adjust.
To finish. Both options can be done safely. I believe low tow is more easily done safely.
Flame suit on.
UH

[Cookie]

You've noted that many fly low tow "too low"

I've noted that many fly high tow "too high"

Hmmmm?



Cookie

[Cookie]

Only one "freak" incident I saw where low tow may have caused an "issue"

Well actually it was a high tow gone bad...

It was a rough day...the glider pilot was seemingly attempting to fly "high" tow.

For some reason, the glider went low....the rope broke...

The rope blew back over the glider and made a complete 360 "wrap" around the glider fuselage....the glider landed with the rope still wrapped around it. The glider canopy had a long "burn mark" where the rope slid along it.

Luckily the rope did not get wedged into an aileron gap or tail surface.

Cookie






On Monday, February 25, 2019 at 8:54:59 AM UTC-5, uncl...@ix.netcom.com wrote:

[Cookie]

You make some very good arguments in favor of low tow....Does that mean you win the overall argument?...I dunno?..most glider ops in USA still use high tow. ( guess they have their reasons?)

My concern about all of this tow position stuff is this....
Does using low tow simply mask the "symptom", the larger problem of not-so-proficient glider pilots on tow?

In the incidents I've seen or heard about... It was always the glider pilots lack of skill, or inattention, which caused the problem...the root cause was the glider pilot, not the tow position...

That being said....If I were a tow pilot (I'm not)...and I were towing somebody in a glider, who I had no idea of his ability, experience, etc....I would be much happier if he flew low position...

Cookie




On Monday, February 25, 2019 at 8:54:59 AM UTC-5, uncl...@ix.netcom.com wrote:

[Steve Koerner]

Hank -

Do you have any thoughts on the separate problem of tow too slow with a ballasted glider? Wondering which might be better for that big problem. Maybe that problem is the same either way.

Second, I'm wondering about how glider lift off occurs for a low tow. Do you typically lift off with the towplane then immediately transition to low position or does the glider attempt to hold it down on the runway until the sight picture is correct for low tow?

[uncl...@ix.netcom.com]

On Monday, February 25, 2019 at 10:09:35 AM UTC-5, Cookie wrote:
> You make some very good arguments in favor of low tow....Does that mean you win the overall argument?...I dunno?..most glider ops in USA still use high tow. ( guess they have their reasons?)
>
> My concern about all of this tow position stuff is this....
> Does using low tow simply mask the "symptom", the larger problem of not-so-proficient glider pilots on tow?
>
> In the incidents I've seen or heard about... It was always the glider pilots lack of skill, or inattention, which caused the problem...the root cause was the glider pilot, not the tow position...
>
> That being said....If I were a tow pilot (I'm not)...and I were towing somebody in a glider, who I had no idea of his ability, experience, etc....I would be much happier if he flew low position...
>
>
> Cookie
>
>

> Not trying to win anything but if I can clear up some misinformation it could be a good thing. Knowledge is important and commonly limited.
Low tow may mask proficiency issues a bit simply because it is a bit easier to do- my experience.
I completely agree that proficiency is a major concern. How many things do we do only 20 or 30 times a year that can kill somebody if we do it wrong?
The point Chris R made about rope length is also very important.Short ropes make position errors more critical.
UH

[uncl...@ix.netcom.com]

Too slow is obviously a problem in either position- duh! That said the first thing most will feel in high tow is poorer position control when sinking into the wake. Control isn't as much an issue in low tow but it still feels bad.
In a flapped ship adding some more flap can get a bit of lift without pulling the leading edge up and reducing control.
Ships with no flaps are just screwed.
On takeoff I teach:
Lift off normally and get stable at a comfortable height, say 6- 8 feet.
Hold that position as the tug accelerates and lifts off.
When the tug starts to climb hold the glider down a bit so the tug outclimbs the glider . The glider stays in ground effect and the tug wake is dissipated.
As the tug wake starts to be above the glider smoothly transition to climb in the low tow position. Avoid doing this late and then having to climb hard to catch up.
Easier to do than describe but it feels very odd to someone not famailiar.
UH

[Tango Eight]

Jus' for clarity, the only bits I quoted Chris on are in quotes. I get the blame for everything else in that post.

T8

[Charlie M. (UH & 002 owner/pilot)]

OK, I will start with.....I am biased to UH, he was one of my early instructors and we have other connections.

The "only" time I see an issue with low tow is with a VERY high wind gradient and someone being waaaayyyyyy too low near the ground.
The relevant airspeed of the tug vs. the glider (especially on a weaker tug) may put the glider in a poor position speed wise.

I will say, I have towed out of our field on very gusty days with, about a 45* cross wind, near gross weight (say, a ASW-20 A or C, so, about 9lbs/sqft.).
Yes, it ''twas sporty down low", why not? Big cross wind, over trees, higher wingloading, etc.

I have had rope breaks and a few TP dumped ropes while low tow, the rope just drops below the glider, try to drop a broken rope over the field on the grass.

As to the towpilots, what I have heard is that low tow allows them to trim a climb in their ship, thus less tiring over a day. High tow is usually outside the trim limits, thus always using your arms to maintain a climb pitch. Part of this is a correct low tow puts the glider basically on the pitch line from tug spinner and down the rope to the glider...

I remember decades ago in upstate NY at a contest. Summer day, ballast, weak towplane (leaving site and tug out, not trying to slam the site). I started in high tow. We were attempting to do circles close to the field to clear terrain, I ended up in low tow since I was just hanging on. It appeared that it helped climb a bit, but I was not happy.

In general, the "perfect world" done wrong/incorrect still sucks and may be dangerous.

At our place, we teach both.
Other places, we do as they do, but if it gets bad, we may fall back to what we have more time with.

A search on RAS will likely pop up multiple threads with the same basic question, which tow is better?

I guess this discussion is akin to, "what contest rules should we use?", sheesh......

[chip.b...@gmail.com]

I flew at Valley Soaring for a while and did low tow. Worked fine. The only negative I heard was that the glider appears to be lower in the first critical phase of climb so it takes longer to get to the 200' safe 180 turnaround point. But I've also heard that low tow is more efficient because there's less/no trim drag from the towplane using up elevator to keep the tail down and therefore climbs faster. So perhaps it's a wash.

I'll move into low tow on cross-country aerotows if I've briefed the tow pilot or can communicate with him/her because it seems easier to hold position.

Yes, kiting a glider is going to upset the towplane regardless of the tow position. But at least if you're in low tow, you'll feel the wake as you pop up thru it, which provides an alert that might help prevent situations as was described in the NTSB report where the glider pilot may have taken his eye off the towplane for a few seconds.

Chip Bearden

[Charlie M. (UH & 002 owner/pilot)]

To add a tiny bit, some high tow proponents have said, "I want to clear low obstructions, thus I fly high tow....!"
I usually counter with, if the towplane clears, there is typically enough energy for the glider to clear, even from low tow. Also, as Chip stated (and I agree), low tow does not require as much parasitic drag from the towplane tail to maintain a climb angle, thus more efficient. This also means the towplane is marginally higher clearing an obstacle, thus more energy for the sailplane to clear even if too low doing low tow.
Again, big wind gradient can be a negative factor if too low.

We break ground, sit in ground effect (pretty much the most efficient place for any aircraft), let towplane accelerate, break ground, then establish a climb. Once the sight picture looks good, the sailplane starts a climb.
Turbulence from towplane wing wash/vortex is essentially "0" since that does not really form until some climb is done. By the time it starts, the sailplane should be starting up.

As stated before, any method done wrong/incorrect is still poor.

[Cumungus]

Steve.

First reading this post brought back memories of the R11 Truckee contest in 2015.
If I remember correctly, you struggled tremendously to take off each day.
It is understood that R11 was hosted at an advanced site, though even in a fully loaded racing glider, it does not require superhuman skills to get off the ground and tow safely.
Note also that ground looping half way down the runway is not the fault of the wing runner...
Further reports from towpilots indicated that they could rarely see you in their rearview mirrors. In fact, there were several occasions where you were almost released by the towplane.

My best advice is to consider practicing normal takeoff and tow, where you keep the towplane's wheels on the horizon and the rope tight with basic techniques.
Intentional high tow and low tow in heavy, high performance gliders on rough days make things scary for the towpilot and their friends and family.
It is important to be able to recover from unintentional position upset, but there's no reason to intentionally upset your position.
Please, do us all a favor and stay in the standard tow position.

P.S. I hope to never have to see your gear doors up close again...

[Steve Koerner]

Hello there Cumungus.

Who are you?

Why would you choose to ridicule me and make your wise suggestions over the internet?

And, why four years after the fact?

[Ramy]

Sounds to me that this method of staying low in ground effect for low tow position will increase the time we spend in the dangerous zone below 200 feet, in addition to transitioning through the wake while low and slow. Personally I prefer to spend as less time as possible down low, and would rather transition to low tow position at safe altitude and safe speed. Especially at high density altitude such as we have in the west, fully ballasted combined with not so powerful towplane, the last thing I would want is to purposely stay in ground effect at the end of the runway while the tow plane slowly climbs higher. I never tried this, so maybe it is not as bad as i think it is.

Ramy

[tom.k...@gmail.com]

In Australia we now transition higher, I use around 200’ before going into low tow.
I have flown high tow at many overeas comps and still find low tow much more stable.
The only time I fly high tow at home is on long cross country tows where I also pull the gear up (nose hook only!) and let the tug pilot accelerate in level flight.
The issue of tug pilots ignoring what type and weight of glider behind them is much more of a safety issue than the simple high/low equasion.
(I am a tug pilot too!)
Tom

[Tango Eight]

On Tuesday, February 26, 2019 at 10:16:56 PM UTC-5, Ramy wrote:
> Sounds to me that this method of staying low in ground effect for low tow position will increase the time we spend in the dangerous zone below 200 feet, in addition to transitioning through the wake while low and slow. Personally I prefer to spend as less time as possible down low, and would rather transition to low tow position at safe altitude and safe speed. Especially at high density altitude such as we have in the west, fully ballasted combined with not so powerful towplane, the last thing I would want is to purposely stay in ground effect at the end of the runway while the tow plane slowly climbs higher. I never tried this, so maybe it is not as bad as i think it is.
>
> Ramy

One reason I will never do this in a ballasted glider is wind shear.

Low tow increases the glider pilot's vulnerability to a slow tow.

best,
Evan

[uncl...@ix.netcom.com]

On Tuesday, February 26, 2019 at 10:16:56 PM UTC-5, Ramy wrote:

> Sounds to me that this method of staying low in ground effect for low tow position will increase the time we spend in the dangerous zone below 200 feet, in addition to transitioning through the wake while low and slow. Personally I prefer to spend as less time as possible down low, and would rather transition to low tow position at safe altitude and safe speed. Especially at high density altitude such as we have in the west, fully ballasted combined with not so powerful towplane, the last thing I would want is to purposely stay in ground effect at the end of the runway while the tow plane slowly climbs higher. I never tried this, so maybe it is not as bad as i think it is.
>
> Ramy

My experience is that the slightly improved takeoff performance puts the glider at an equal to slightly higher height shortly after transition to the tug climbing attitude.
UH

[uncl...@ix.netcom.com]

If excessively low on tow wind shear can be a factor. Properly flown, my experience is that it is not.
Possibly you can explain your second contention. Slow is slow no matter which position you are in.
UH

[Charlie M. (UH & 002 owner/pilot)]

And I think this is an example of not being properly trained in low tow.
You are in ground effect until the towplane reaches the proper sight view in front of the glider which is not too far off the ground.
If you are looking up at the bottom of the towplane, you waited too long. This would accentuate the negative effect of wind gradient.

[Tango Eight]

I think your argument here is that "a properly flown low tow doesn't hurt much." In which case my point has been made, yes?

T8

[Dan Marotta]

Some gliders have the CG hook just forward of the gear doors.  I always
raised the gear in my LAK-17a on tow (at a safe altitude, of course) to
get a marginal improvement in climb rate.  Everyone says that low tow is
best for XC tows.  I've only been on the front end of the rope on an XC
tow, so I can't address the back end.

--
Dan, 5J

[Dan Marotta]

While I agree that "slow is slow", I think it's much better to be in
high tow position and be able to sink to low tow if the tug gets too
slow.  I've been dangling on the end of a slow rope with a full load and
had to start dumping while on tow.  It's not comfortable.

Of course that proper thing is to not get slow and I blame this on an
inexperienced tuggie who strives for a good climb rate at the expense of
the glider.

--
Dan, 5J

[Charlie M. (UH & 002 owner/pilot)]

I would say, a "properly flown tow" doesn't hurt much.
There are issues in ANY formation flying, a glider aero tow is formation flying.
Do we at least agree on that (that an aero tow is formation flying)?

Any aero tow (or even winch launch, etc.) has some risk.
I have seen people fly low tow as a "new thing" when they normally did high tow. Common issue is waiting late to climb with the towplane.

As I stated earlier, this discussion has been hashed out on RAS before as well as other places.
To me, this is a "no win" for anyone.
We train for both, which is good.
I normally fly whatever tow is "usual" at a site.

[Mike the Strike]

All my early flights were in South Africa, where low tow was the norm at my home field. I only remember one problem, when my heavily-ballasted Jantar-1 over-ran the towplane when it slowed on hitting a strong thermal. The towrope snaked over the canopy then passed over my left wing in a large loop. I recovered just fine, but it did catch my attention!

I have had many more problems trying to maintain high tow in a fully ballasted Discus 2b and had several occasions where I ran out of elevator authority due to a slow tow, usually releasing prematurely. I managed to stay on once in such a slow tow, but sank into low tow position and had insufficient elevator to resume high tow at the speed flown. Maybe low tow has a slight aerodynamic edge with modern ships?

Mike

[Bruce Hoult]

On Tuesday, February 26, 2019 at 11:02:17 PM UTC-8, tom.k...@gmail.com wrote:
> In Australia we now transition higher, I use around 200’ before going into low tow.
> I have flown high tow at many overeas comps and still find low tow much more stable.
> The only time I fly high tow at home is on long cross country tows where I also pull the gear up (nose hook only!) and let the tug pilot accelerate in level flight.

Weird, because long cross country tows is exactly the one time the rest of us use low tow!

The height difference between a good low tow and a good high tow isn't much anyway. Twenty feet / six metres maybe? Maybe less.

[Cookie]

Yes!

Above the wake during a level (not climbing) tow, will place the glider quite a bit above the tow plane...not a good place to be...

Low tow during level tow, just barely below the wake will place the glider only very slightly lower than the tow plane...a good place to be...

So...anybody winning the argument yet? LOL


Cookie

[Cookie]

So....I think you are bringing up a completely different issue now...the speed of the tow. If the problem is too slow of a tow....the solution is to get the tug to go faster...the solution is not high tow or low tow....

Accepted procedure is for the glider pilot to brief the tow pilot on any pertinent information needed for the tow...such as airspeed to be used...

Many previous discussions on why a glider can fly at a fairly slow airspeed in free flight, yet can't comfortably fly that slow while on tow.

Cookie

[tom.k...@gmail.com]

You do realise high and low refer to the slipstream don’t you!?

Speed of tow is the most important thing, I have not had so much flying in the USA but it is a problem at comps here when tug pilots used to towing slow two seaters and empty older gliders and turn up at a comp to tow heavily ballasted gliders. I understand there have been accidents over there from this.
ASGs and JSs need more speed than 2-22s but some tug pilots cannot seem to see that! ;)

[Tom BravoMike]

I have always believed the wake basically goes DOWN behind the tow plane, being compressed, i.e. heavier, air, and/or maybe for other reasons. I don't remember feeling any wake turbulence just following the tow plane at the same height, climbing or level flight.

[Surge]

On Monday, 25 February 2019 15:28:09 UTC+2, Tango Eight wrote:
> Chris Rollings:
> Being in low-tow when that happens
> simple makes the sunsequent event take about half a second longer - not
> enough extra time to greatly increase the chance of releasing before the
> critical point."

So low tow does offer more time to react to a tug upset.
From the info at hand it appears that a tug upset occurs over a duration of about 3 to 4 seconds. An additional 0.5 seconds on 4 seconds is a 12.5% increase.
Why throw a free 12.5% additional safety margin away?

[Martin Gregorie]

On Wed, 27 Feb 2019 18:12:56 -0800, Tom BravoMike wrote:

> I have always believed the wake basically goes DOWN behind the tow
> plane, being compressed, i.e. heavier, air, and/or maybe for other
> reasons. I don't remember feeling any wake turbulence just following the
> tow plane at the same height, climbing or level flight.
>

Its caused by a wing generating lift. If you assume that the wake's
downward angle is 1/3 of the wing's AOA you won't be far wrong.


--
Martin | martin at
Gregorie | gregorie dot org

[Bruce Hoult]

On Thursday, February 28, 2019 at 12:35:13 AM UTC-8, Martin Gregorie wrote:
> On Wed, 27 Feb 2019 18:12:56 -0800, Tom BravoMike wrote:
>
> > I have always believed the wake basically goes DOWN behind the tow
> > plane, being compressed, i.e. heavier, air, and/or maybe for other
> > reasons. I don't remember feeling any wake turbulence just following the
> > tow plane at the same height, climbing or level flight.
> >
> Its caused by a wing generating lift. If you assume that the wake's
> downward angle is 1/3 of the wing's AOA you won't be far wrong.

So maybe 2 to 3 degrees from a towplane, a 1:20 to 1:30 slope, 2 or 3 metres at the end of a 60m towrope.

[Cookie]

What is the more controlling factor, is the tow plane is continuously climbing up and away from the wash. Leaving the wash behind if you will.

At say 60 knots, and 10 knots climb..that is a 1 in 6 angle.....giving the glider pilot the impression that the wash is dropping...but really the glider and towplane are climbing compared to the wash.

I've done many "level" (not climbing) tows. The wash essentially comes straight back. To fly outside of the wash, the glider must be either above the tow plane, or below it.


Cookie

[Tango Eight]

I think we have two distinct types of events to consider, that differ in their causes, effects and kinetics.

In the case of "kiting" accidents, what does the towplane in is the *pitch of the glider*, not the pitch of the tow rope. It's the acceleration of the glider that produces the dangerous deceleration of the tow plane. We think that beyond a critical (glider) pitch of about 30 degrees, the situation is not recoverable. I don't think low tow buys you much in this scenario.

In "distraction" events, the glider remains below the critical pitch, the situation remains recoverable much longer, the problem is caused when the glider drifts so far out of position that the angle of the rope becomes a problem for the tug. Or it may turn into a kiting event.

Here's the order of priorities for prevention of both types of problems:

1. PIC that maintains situational awareness and positive control, all the time.
2. Rope of reasonable length. We find that 200 - 225' works well. Longer gets to be a problem for recovery at our airport.
3. Tow position probably improves margin in distraction scenario.

I have reservations about using low tow at our club because a PTT below 200' means something is going to get bent with high probability (it's roughly a ten second window of time between able to land straight ahead and able to make a safe 180). On a 225' rope, low tow is about 30 feet lower than high tow, why throw away 15%? :-)

best,
Evan

[Charlie Quebec]

Put simply, kiting accidents just don’t happen on low tow. The only time I’ve ever seen a tug upset was a glider that had to use high tow
fortunately, the glider released immediately and landed ahead. Again, to be simple, the tug is at all times visible to the glider pilot, it cannot disappear
under the nose, a feature unique to low tow. As for the small height gain, I have the opposite view, being lower gives a better chance of straight ahead landings.
I can’t recall a single accident caused by an upset in low tow. I stay as low as possible after lift off, and wait for the tug to climb above me and stay there.
As my glider has winch hook only, I would not risk the tug pilots life by doing high tows. All I’m seeing is spurious arguments in favour of high tow, that put the risk on the tow pilot not the glider pilot.
I’d rather crash myself than kill an thuggish, but that’s just me.

[cern...@gmail.com]

Low tow isn't common in Italy, and in the EU as far as I know. We practice the low-tow position during basic training, then it's at the pilot's discretion. Occasionally during the season I use it for a minute or so, and every time I make my first flight on a new type.

What's the standard low-tow procedure? Do you still take-off in the high-tow position then transition to low-tow at a given altitude?
Or do you watch the towplane climb, then start climbing when "it looks about right"? the latter seems scary to me (as I've never done it).

Thanks!

Aldo Cernezzi

[Charlie M. (UH & 002 owner/pilot)]

Low tow is.....sailplane breaks ground, stays close to ground (since close ground effect basically negates the sailplane drag), let towplane accelerate, lift off, when towplane "looks about right" follow it up.

This is the short version.

Having, taught newbs for both, low tow seems easier and safer.

There is ALWAYS the outlier where, "I think high tow would have been better".
To me, sorta like, "I won't wear seat belts because I knew of a case where they were thrown free in a crash and survived because they didn't wear seat belts".

I stick with low tow, but teach and fly both.

As I stated before, this is a "no win" conversation.

[Jonathan St. Cloud]

I received my glider training in Minden. Some of you might have heard rotor can be a real thing there. From day one I was conditioned, if I ever lost sight of tow plane to release immediately, and I have! Other than training the only low tow I have been in was back in the 90's we (local not Minden) had a string of very poorly (not) trained tow pilots. It was so bad pilots were making signs that said "Fast tow". To this day there are no radios in the local tugs :( I was flying a loaded ASW-24 and was so slow and low that the tow rope was basically just inched in front of the leading edge (CG Hook). Thank goodness for the Nixon/Murray water system, dumps fast. Since this tow pilot was towing away from field low and slow, I to wait until I thought I could make it back to airport before I released. On the ground I spoke to the tuggie. He had no clue gliders carried water ballast. I held up a sign that said I had water ballast before the tow he thought that was drinking water! That same day he towed a 1-26 at 70 knots straight away from airport with no mind of return to airport for the 1-26 driver. Since I got back into gliding our tow pilots are some of the best pilots of anything I have ever met! Perhaps all this boils down to improper initial training. If I was sleeping, dreaming of being on tow, and in the dream lost sight of tow plane, I would still be pulling for that release. Of course I don't mess with anything else on tow because I have been trained while flying tow, that is the only thing you should be doing!

In Minden before each training session we briefed the tow and we briefed immediate release if lost sight. It was much more than cursory, or something we mentioned a few times, it was part of every before flight emergency procedure spoken outloud.