Standardization in Slack Rope Recovery?

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

On Saturday, February 6, 2016 at 11:57:42 AM UTC-5, John Cochrane wrote:
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

I don't believe any of us said to, "yaw the nose at the last moment".

It's more of, "Get the nose started to the side (using rudder)" so you:
-avoid the loop
-slow the glider
-sorta maintain relative altitude to the towplane
-maintain sight of the towplane

It should be obvious that yawing inside the turn (if the towplane is turning) does not help at all. So, rudder away from the turn. It does not take much.

When the rope comes tight, it's not a huge swing in either ship, it's just a realignment and a lessening of rope shock.

If all else fails, drop the rope (especially if you lose sight of the towplane).

On Sunday, February 7, 2016 at 10:44:44 AM UTC-5, Charlie M. (UH & 002 owner/pilot) wrote:
On Saturday, February 6, 2016 at 11:57:42 AM UTC-5, John Cochrane wrote:
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

I don't believe any of us said to, "yaw the nose at the last moment".

It's more of, "Get the nose started to the side (using rudder)" so you:
-avoid the loop
-slow the glider
-sorta maintain relative altitude to the towplane
-maintain sight of the towplane

It should be obvious that yawing inside the turn (if the towplane is turning) does not help at all. So, rudder away from the turn. It does not take much.

When the rope comes tight, it's not a huge swing in either ship, it's just a realignment and a lessening of rope shock.

If all else fails, drop the rope (especially if you lose sight of the towplane).

Out of curiosity, I looked up "Slack towline" in the "Joy of Soaring" (mine is from 1974, pg28), basically what I posted is what is in the book (at least used to be a "standard" manual in the US).

The trouble I've found with attempts to slow down with slip or spoilers is that it's very hard to get timing right. You want to slow down while the slack is getting bigger. You don't want to be slowing down once the slack is big, or as the rope is coming out. A second delay, and you're making things worse.

A steady slip or spoilers in very rough air can be quite helpful for keeping slack from starting. Some times on long retrieve tows I put a few degrees of slip in and leave it there, which smooths things out nicely.

John Cochrane BB

On Sunday, February 7, 2016 at 12:02:53 PM UTC-5, John Cochrane wrote:
Some times on long retrieve tows I put a few degrees of slip in and leave it there, which smooths things out nicely.

I haven't done many retrieve tows of sufficient distance to obviate the tow pilot's typical advice that "I'll keep climbing until you release". But when I have, I've been reminded of how much easier it is to get slack in the rope once the tow combination has leveled off.

A little slip works. But I like to move into low tow position, assuming I've briefed (or radioed) the tow pilot ahead of time. There's very little tendency to get slack in the rope. Low tow can be discomforting visually if you've never done it (a different angle) so it's worth practicing. Or fly with an operation like Valley Soaring Club (NY) that uses low tow almost exclusively.

Chip Bearden

On Sunday, February 7, 2016 at 3:32:32 PM UTC-5, wrote:
On Sunday, February 7, 2016 at 12:02:53 PM UTC-5, John Cochrane wrote:
Some times on long retrieve tows I put a few degrees of slip in and leave it there, which smooths things out nicely.

I haven't done many retrieve tows of sufficient distance to obviate the tow pilot's typical advice that "I'll keep climbing until you release". But when I have, I've been reminded of how much easier it is to get slack in the rope once the tow combination has leveled off.

A little slip works. But I like to move into low tow position, assuming I've briefed (or radioed) the tow pilot ahead of time. There's very little tendency to get slack in the rope. Low tow can be discomforting visually if you've never done it (a different angle) so it's worth practicing. Or fly with an operation like Valley Soaring Club (NY) that uses low tow almost exclusively.

Chip Bearden

I believe a number of training manuals suggest using low tow for long tows (like Middletown, NY to HHSC, NY...).
Yes, Middletown, NY is almost exclusive low tow (except for some training and what a transient pilot likes).