Standardization in Slack Rope Recovery?

Where I fly only low position aerotows are performed and even in turbulent conditions with glass gliders, rope slack doesn't seem to be much of a problem.

Are high position aerotows more prone to developing rope slack?

On Tuesday, February 2, 2016 at 9:31:22 PM UTC-7, Surge wrote:
Where I fly only low position aerotows are performed and even in turbulent conditions with glass gliders, rope slack doesn't seem to be much of a problem.

Are high position aerotows more prone to developing rope slack?

I flew in low tow in South Africa for many years and clearly remember a few instances of very slack rope. One time the tow plane flew into a strong thermal and slowed so fast that the tow rope snaked back over my canopy and far down the fuselage. This was in a Jantar-1 that had the hook under the front belly.

I was taught the offset and yaw recovery method rather than the dive and hope-for-the-best method and I use it fairly often in our strong summer conditions. I am much more scared of simulated rope breaks below 200-feet!

Mike

On Tuesday, February 2, 2016 at 11:31:22 PM UTC-5, Surge wrote:
Where I fly only low position aerotows are performed and even in turbulent conditions with glass gliders, rope slack doesn't seem to be much of a problem.

Are high position aerotows more prone to developing rope slack?

I would say yes, it's a lot easier to let the nose drop and accelerate, thus causing slack.
In low tow, an easy way to get slack is to turn inside the towplane.

At our field, almost all our tows are low tow. I mostly do high tow at contests, training and checkrides.

maybe the question is not why there are different techniques for required tasks.

rather, why do CFIs, who are giving checkouts and BFRs to experienced pilots (as opposed to primary instruction), demand one specific method?

Shouldn't they use the "Satisfactory Performance" criteria as outlined in the PTS, which says:

Satisfactory performance to meet the requirements for certification is
based on the applicant's ability to safely:

1. perform the TASKs specified in the AREAS OF OPERATION for
the certificate or rating sought within the approved standards;

2. demonstrate mastery of the aircraft with the successful outcome of
each TASK performed never seriously in doubt;

3. demonstrate satisfactory proficiency and competency within the
approved standards; and

4. demonstrate sound judgment and ADM.

--bob

On Tuesday, February 2, 2016 at 11:31:22 PM UTC-5, Surge wrote:
Where I fly only low position aerotows are performed and even in turbulent conditions with glass gliders, rope slack doesn't seem to be much of a problem.

Are high position aerotows more prone to developing rope slack?

Where we fly low tow is the standard procedure. We rarely, if ever, get significant slack during tow, even in early training. We have to go out of our way to teach slack rope procedures.
To get slack you most commonly are coming down from a somewhat too high position that is not likely in low tow.
UH

The best way to demonstrate slack rope recovery is to take your BFR on a wave day with rotor in the pattern. Scenario based BFR.

I once took a very instructive BFR with Marty Eiler at Cal City. Needless to say, with lots of wave/rotor flying, Marty had plenty of experience in what actually works in real slack rope situations. He chuckled at the yaw the nose at the last moment stuff, encouraging me to try it and see how it made matters worse.

His technique is to stay a bit off to one side, high if possible, and make sure the glider is banked toward to towplane with nose low and pointing towards the towplane as the slack comes out.

The key is to avoid a kiting attitutde. This makes absolute sense. Think about rope coming taut with the glider nose up and banked away in a kite attitude, vs. nose down and banked toward the tug. The kite is going to be a lot rougher.

When the rope pulls the glider, you don't want that to raise the glider's angle of attack, so the lift force fights the rope. Ideally, the rope pull should lower the glider's angle of attack, and the lift force should be somewhat in the direction of the rope. The key point is the glider's attitude when rope comes out, not relative motion.

The yaw at the last minute idea, beyond being very hard to do (especially bouncing around in rotor), will typically leave the glider slightly banked away from the towplane, unless you're very very good and also banking the other way at the same time. It also points the glider away from the tug. Trying to speed up at the last minute means you get lower and lower. Any amount of last minute maneuvering is going to be very hard to do in the real situation of extreme turbulence. Holding a good attitude is easier.

After a lot of subsequent experimentation I haven't found a better technique, at least one that I can perform reliably.

John Cochrane BB

When the rope pulls the glider, you don't want that to raise the glider's angle of attack, so the lift force fights the rope. Ideally, the rope pull should lower the glider's angle of attack, and the lift force should be somewhat in the direction of the rope. The key point is the glider's attitude when rope comes out, not relative motion.

Interesting technique John, this does sound a little familiar to the "Freeze it, fix it, face it method," perhaps just explained a bit better. The one thing i don't understand is the line above...Wouldn't a nose-low situation with towplane-induced pulling the nose up cause an increase in AOA, not a decrease? I can, however, see that configuration helping from a total energy perspective, but not sure that attributing the additional "cushion" to an AOA change, as much as preventing a dive on the towplane.

Not trying to argue or disprove, just clarify... Thanks for the technique, i will have to try it out this spring.

Chris

On Saturday, February 6, 2016 at 7:57:42 PM UTC+3, John Cochrane wrote:
His technique is to stay a bit off to one side, high if possible, and make sure the glider is banked toward to towplane with nose low and pointing towards the towplane as the slack comes out.

That's largely what I do.

I think the key is that if you're getting slack rope developing it's because you're going faster than the towplane.

The amount of slack that develops is the integral (sorry) of your excess speed and the amount of time you have the excess speed.

I don't like to throw away energy by slipping or using the brakes. It should be a very rare thing indeed.

Much better to store the energy by climbing. You can then get most of the speed back by descending, lessening the jolt as the rope comes tight.

The sooner you start to climb the less slack accumulates.

It doesn't matter how high you are above the tow plane as long as the rope is slack. So you've got 150 ft of altitude above the towplane and 150 ft below the towplane to play with. That's a lot.

Also 150 feet to the side. Most people seem to forget this. You can bring out the slack when *you* want to by flying out to the side, and turning back as it's about to come tight. And with no risk whatsoever of a tug upset. If you get the slack out while you're out to the side, turning back into the middle gives you more more rope. It means that you can have no jolt even if you're going considerably slower than the towplane at that point.

So, yes, a combination of higher (to store energy that you can turn back into speed) and to one side (for visibility, to take out the slack early, and to "put back" a controlled amount of slack as needed to eliminate the jolt..

Both descending and coming back from the side help you to match speeds.

The big big key is to concentrate on controlling the amount of bowing in the rope and the trend in the amount of bowing, not at the actual speeds and positions.

In the same way that you don't try to calculate the distance to a ridge you want to cross and your height above it, but just look at how the angle is changing and if you can see more or less stuff beyond the ridge as you get closer.

On Sunday, February 7, 2016 at 1:16:52 PM UTC+3, Bruce Hoult wrote:
On Saturday, February 6, 2016 at 7:57:42 PM UTC+3, John Cochrane wrote:
His technique is to stay a bit off to one side, high if possible, and make sure the glider is banked toward to towplane with nose low and pointing towards the towplane as the slack comes out.

That's largely what I do.

I think the key is that if you're getting slack rope developing it's because you're going faster than the towplane.

The amount of slack that develops is the integral (sorry) of your excess speed and the amount of time you have the excess speed.

I don't like to throw away energy by slipping or using the brakes. It should be a very rare thing indeed.

Much better to store the energy by climbing. You can then get most of the speed back by descending, lessening the jolt as the rope comes tight.

The sooner you start to climb the less slack accumulates.

It doesn't matter how high you are above the tow plane as long as the rope is slack. So you've got 150 ft of altitude above the towplane and 150 ft below the towplane to play with. That's a lot.

Also 150 feet to the side. Most people seem to forget this. You can bring out the slack when *you* want to by flying out to the side, and turning back as it's about to come tight. And with no risk whatsoever of a tug upset. If you get the slack out while you're out to the side, turning back into the middle gives you more more rope. It means that you can have no jolt even if you're going considerably slower than the towplane at that point.

So, yes, a combination of higher (to store energy that you can turn back into speed) and to one side (for visibility, to take out the slack early, and to "put back" a controlled amount of slack as needed to eliminate the jolt.

Both descending and coming back from the side help you to match speeds.

The big big key is to concentrate on controlling the amount of bowing in the rope and the trend in the amount of bowing, not at the actual speeds and positions.

In the same way that you don't try to calculate the distance to a ridge you want to cross and your height above it, but just look at how the angle is changing and if you can see more or less stuff beyond the ridge as you get closer.

OK, "no risk whatsoever of a tug upset" from the rope coming tight while out to the side was a bit too strong. It's better than pulling the tail up, but it can still cause problems if at a sufficiently low level, as in this accident near Christchurch:

http://www.stuff.co.nz/national/7131...l-crash-report