high tow vs low tow

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.Â* I've been dangling on the end of a slow rope with a full load and
had to start dumping while on tow.Â* 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.

On 2/27/2019 6:52 AM, wrote:
On Wednesday, February 27, 2019 at 7:45:46 AM UTC-5, Tango Eight wrote:
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
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

--
Dan, 5J

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.

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

On Tuesday, February 26, 2019 at 11:02:17 PM UTC-8, 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.

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



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.

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

On Wednesday, February 27, 2019 at 2:29:16 PM UTC-5, Mike the Strike wrote:
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

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!

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.

On Wednesday, February 27, 2019 at 2:21:01 PM UTC-8, Cookie wrote:
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

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?

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