Glider Mid Air Collision at World Championships

[Oscar]

There's airmanship required where the positioning of gliders in the thermal is recommended to allow best vision and situational awareness. Plus the important method of joining at leaveing the thermal. Leaving has many methods and it not just peeling off. Mike

My most treasured memory of a thermal, was in a Standard Libelle, trying for a 300k task - along with a whole gaggle of others who had selected the same task. First turning point out of Narromine was Coonamble. I'd booked a Hornet for the task, and been checked out by John Rowe ( his current WC-record holding Hornet, a real honour for me!), but there'd been a double-booking, so John asked me to use the H201B Libelle. My 'check' with John was: 'Here's the water-dump, fill it up before you go'. I'd never flown a Std Libelle, but had some time in a Club Libelle, so that's not as cavalier as it sounds.

 

Around that area, thermals are usually marked by Cu-Nim at the top (unlike Tocumwal, where blue thermals are the general rule, and MUCH harder to find), and the day was just starting to bubble. This was the only marked thermal in sight between Narromine and Coonamble, and everybody headed for it. I was a relative latecomer, but on the upside, it was really starting to get into stride by then and I got a really great ride, climbing through four (from memory) others, including a Std. Cirrus which was supposed to have better performance.

 

I suppose I SHOULD have called the Std. Cirrus up and told him that his wheel was still down BEFORE I climbed through him... He thanked me for the message, in a voice that took some heat out of my water-bottle for sure..

 

 

[johnm]

Remind us oscar ..... whats the water ballast for?

 

Whats the forward lhs cockpit lever .... pilot slidind it fore and aft ?

 

Thanks

 

 

[Oscar]

Water ballast gives you penetration, and being (at least mostly) in the wings, better gust speed capability. You could think of it - as a rough analogy - as being like loading up a ute and having more kinetic energy at the bottom of a hill to keep you rolling up the other side, and also getting a better ride over rough road. You lose on the climb, but in a good day, there's enough oomph in a thermal ( or ridge lift) to compensate.

 

The forward lever that the pilot plays, will be the flaps, which in the higher-performance gliders have reflex capability that unloads the wing drag by effectively removing a bit of the wing lifting area, and lowering the force required from the elevator as well to counter the 'tipping' force of a standard wing by moving the C/P slightly forward on the wing. That allows you to fly at higher speed with less drag through sink or still air because the fuselage doesn't have to be nosed-down to get the speed up - from inside the cockpit, it's a bit like putting your foot on the accelerator of a quite powerful car - you don't get the 'nose-down, higher speed' feeling, the horizon remains basically where it was but the ASI winds around quite convincingly. Conversely, when you hit lift, you can use positive flap to slow you down and increase the wing area to maximise an area of lift.

 

If you look at the video on: Flying Tiger Country, you'll see the pilot playing the flaps to cross areas of sink, but you will also see that the aircraft doesn't pitch down.

 

 

[reefer]

Remind us oscar ..... whats the water ballast for?Whats the forward lhs cockpit lever .... pilot slidind it fore and aft ?

 

Thanks

That would be his Flap handle in his ASG29.

 

 

[diesel]

I flew a Saltoo many years ago. Got my silver c in it. My x/cty was all done in rotor and I contacted the wave above my destination.

 

The same salto had an interesting landing with a broken canopy and the pilots glasses missing.

 

No damage but grass stains on top of the wings.

 

Work that out. A very tough little bird.

 

Chas

 

 

[Blueadventures]

My most treasured memory of a thermal, was in a Standard Libelle, trying for a 300k task - along with a whole gaggle of others who had selected the same task. First turning point out of Narromine was Coonamble. I'd booked a Hornet for the task, and been checked out by John Rowe ( his current WC-record holding Hornet, a real honour for me!), but there'd been a double-booking, so John asked me to use the H201B Libelle. My 'check' with John was: 'Here's the water-dump, fill it up before you go'. I'd never flown a Std Libelle, but had some time in a Club Libelle, so that's not as cavalier as it sounds.Around that area, thermals are usually marked by Cu-Nim at the top (unlike Tocumwal, where blue thermals are the general rule, and MUCH harder to find), and the day was just starting to bubble. This was the only marked thermal in sight between Narromine and Coonamble, and everybody headed for it. I was a relative latecomer, but on the upside, it was really starting to get into stride by then and I got a really great ride, climbing through four (from memory) others, including a Std. Cirrus which was supposed to have better performance.

 

I suppose I SHOULD have called the Std. Cirrus up and told him that his wheel was still down BEFORE I climbed through him... He thanked me for the message, in a voice that took some heat out of my water-bottle for sure..

Maybe Steve (the aussie glider pilot) and his his Dad were running Narromine then as they ran it for 7 years some time ago.

 

 

[Bruce Tuncks]

Nice video Oscar, yep you need to use 45 degrees of bank in many thermals especially blue ones. See how the glider in the video had the horizon parallel with the diagonal screws on the instruments? That's 45 degrees.

 

Once I shared a thermal with 2 Nimbus 3's turning at 60 degrees of bank. Their turn was really tight, they looked like the wings were almost vertical.

 

I tell guys that the ideal in an unballasted 15m glider is 45 degrees at 45 knots. Not that I can do this myself, 45 to 50 knots is my best.

 

 

[Oscar]

Blue thermals are certainly different...My only real attempt at an x-c out of Tocumwal was in an IS29D2; in company with a mate in a 29D. Never flown blue thermal skies before, and there's lots of good-looking areas that are not so good because of the irrigation - as I found out. Outlanded in a small paddock, between the irrigation ditches. My mate watched me fail to get lift and went elsewhere, and scraped home - bastard... Ingo was NOT impressed, as he'd said 'have plenty of height before you head off', but didn't mention how much and we'd thought 3,500 was quite reasonable - it wasn't, not for me. I thought I'd cracked it lucky when a Valiant Ute ( yep, there's a hint as to how long ago..) pulled up beside the fence and a VERY attractive young lady got out, wearing a pair of tight stubbies, a halter top, Blundstones and lots and lots ( and lots more) of real tanned skin.

 

Then her two youngsters climbed out of the ute...

 

The D2 was very nice to fly, but my absolute favourite is the 201B; that thermal experience I recounted above was my very first climb in one, ever, and that feeling of having the wings attached to your shoulders was magical. I took it right up into the 'saucer' underneath the cloud until it was skimming the canopy (about 9,000'), and then rolled out on heading, trimmed and locked the stick in my hand until I popped out the side of the cloud. Hit the outflow sink and pushed the nose down and ran for Coonamble. I have never felt so strongly that any other aircraft was doing everything I wanted, before I knew I wanted it done.

 

 

[bexrbetter]

Water ballast gives you penetration, and being (at least mostly) in the wings, better gust speed capability.

When/how often do you dump the water?

 

 

[Exadios]

When/how often do you dump the water?

Whenever needed, but certainly before landing - which is why you often see the last of the water being dumped on final.

 

The idea is to match the amount of water to the day. The stronger the day the more water. A typical competition tactic is to load more water than you think will be needed and, after testing the thermals, dump some before the start. This is because it is very difficult to add water while in flight. :)

 

Also, as the day dies towards the end, it is common to dump some more.

 

 

[Oscar]

1: when you don't need it any more. On a strong day, you'll often see racers dumping water after they have crossed the finish line, using the mass to help them climb back to circuit height after rocketing across the finish line at Warp 5.. You can easily gain 1,000 feet from a 130-knot finish at 100 feet, as the water drains out. You don't want to land with full ballast.

 

2: when you absolutely have to, to stay in the air. When the day dies beneath you, and it's better to get home than 'die fighting'.

 

I am not sufficiently experienced with water-ballasted gliders to be authoritative, but I suspect that for most, it's a 'all or nothing' situation. I guess people with the skill of a Hans-Werrner Grosse or an Ingo Renner could judge, as the day is dying, to dump just enough to make THIS climb work..

 

Edit: see Exadios's post above, he has better information!..

 

 

[bexrbetter]

Thanks Guys, appreciate your time and effort to explain it.

 

 

[djpacro]

Basic principle is that the maximum L/D ratio is a constant so being heavier the glide angle is the same but at a higher airspeed so you get there faster. Sink rate is higher of course hence the need for strong conditions overall.

 

 

[Bruce Tuncks]

A really good coach taught us what Exadios said... You take off with lots of water ballast and then you dump enough so you can stay within the strongest part of the thermal.

 

And Ingo Renner once said that he often beat guys who were carrying too much water.

 

 

[Old Koreelah]

Remind us oscar ..... whats the water ballast for...

...so bored instructors can have fun bombing unsuspecting spectators on the ground.

 

 

[facthunter]

Heavier means turns less tight. Larger radius.. Nev

 

 

[johnm]

wikipedia - could be true .................... some have mentioned these reasons - sounds fair to me

 

'wiki quote

 

The extra weight provided by the water ballast is advantageous if the lift is likely to be strong, and may also be used to adjust the glider's center of mass. Moving the center of mass toward the rear by carrying water in the vertical stabilizer reduces the required down-force from the horizontal stabilizer and the resultant drag from that down-force. Although heavier gliders have a slight disadvantage when climbing in rising air, they achieve a higher speed at any given glide angle. This is an advantage in strong conditions when the gliders spend only a small amount of time climbing in thermals. The pilot can jettison the water ballast before it becomes a disadvantage in weaker thermal conditions'

 

 

[facthunter]

At heavier weights your best L/D speed is higher, your glide angle (all other factors being equal) is virtually the same and your sink rate is higher (in the same ratio as your airspeed increase) If you choose to move the C of G rearwards, you will often achieve a better performance by reducing the aerodynamic down load on the tail. Nev

 

 

[Oscar]

I have to say that I've not heard of using water ballast in the tail, but I'm not across all the latest developments. I do know that some competition pilots used to (carefully) ballast for the max. possible aft. c/g for themselves; John Rowe had done so for his Hornet, and I'm rather smaller than him. My check flight in his Hornet was one of the more 'interesting' flights I've ever had; the tug pilot climbed out at 50 kts and the Hornet wallowed along behind him like a drunken sailor, I had to pedal like buggery to keep it shiny-side up, didn't dare use ailerons.. Then at 800 feet, I thought the tug waggled its wings and bunged off somewhat gratefully.

 

Since I didn't have any height and was not feeling all that comfortable about how it was flying anyway, I decided to see how well the brakes worked in case I had to outland the next day. Turned to line up with the cross-strip, pulled the brakes - they were excellent, my water bottle shot over my shoulder and down into the footwell. Then, as my weight came onto the straps, the in-flight adjustable rudder pedals decided to go forward for a look-see - I hadn't locked them properly in place.

 

I had to swap from using secondary effect of rudder to using secondary effect of ailerons for directional control (evening up the wear, I suppose..) Got it all nicely lined up and then a guy on the strip, right where I had planned to touch-down, started to pull his glider across the strip in front of me without having looked back.. Brakes away again ( fortunately, Narromine has HUGE long strips..)

 

Got it parked; John Rowe came over STEAMING from the ears ( I assume he'd watched the whole messy flight). 'What the hell were you doing there?" I apologised and told him that I'd lost the rudder pedals. He calmed down a bit, and then looked at me (sans a 'chute'), and said something on the lines of: 'Ah, bugger, what do you weigh?" I told him, and he went quiet, then said: 'Tomorrow, you fly with a chute, this thing is ballasted for me'.

 

Then he went to have a chat with the guy who'd pulled his glider over the strip; I suspect it was a somewhat terse conversation.

 

 

[Nobody]

As far back as the original Discus most glider have had a tail tank. It is necessary because the water in the wings is in front of the spar and so forward of the CofG. If you add ~180l of water the CG moves a long way forward, still safe but detrimental to performance. The tail tank balances this out. When the tail tank is full there is a requirement to dump the water when the temperature gets to a certain value( i cant remember at the moment) lest the water freeze in the tail and cause structural damage. The small volume is prone to freezing before the main wing tanks. The temperature gauge is a required instrument if you use the water ballast.

 

 

[Exadios]

I have to say that I've not heard of using water ballast in the tail, but I'm not across all the latest developments. I do know that some competition pilots used to (carefully) ballast for the max. possible aft. c/g for themselves; John Rowe had done so for his Hornet, and I'm rather smaller than him. My check flight in his Hornet was one of the more 'interesting' flights I've ever had; the tug pilot climbed out at 50 kts and the Hornet wallowed along behind him like a drunken sailor, I had to pedal like buggery to keep it shiny-side up, didn't dare use ailerons.. Then at 800 feet, I thought the tug waggled its wings and bunged off somewhat gratefully.Since I didn't have any height and was not feeling all that comfortable about how it was flying anyway, I decided to see how well the brakes worked in case I had to outland the next day. Turned to line up with the cross-strip, pulled the brakes - they were excellent, my water bottle shot over my shoulder and down into the footwell. Then, as my weight came onto the straps, the in-flight adjustable rudder pedals decided to go forward for a look-see - I hadn't locked them properly in place.

 

I had to swap from using secondary effect of rudder to using secondary effect of ailerons for directional control (evening up the wear, I suppose..) Got it all nicely lined up and then a guy on the strip, right where I had planned to touch-down, started to pull his glider across the strip in front of me without having looked back.. Brakes away again ( fortunately, Narromine has HUGE long strips..)

 

Got it parked; John Rowe came over STEAMING from the ears ( I assume he'd watched the whole messy flight). 'What the hell were you doing there?" I apologised and told him that I'd lost the rudder pedals. He calmed down a bit, and then looked at me (sans a 'chute'), and said something on the lines of: 'Ah, bugger, what do you weigh?" I told him, and he went quiet, then said: 'Tomorrow, you fly with a chute, this thing is ballasted for me'.

 

Then he went to have a chat with the guy who'd pulled his glider over the strip; I suspect it was a somewhat terse conversation.

Aft CoG is scary. And 50 Knots is too slow. I'm surprised that the tug didn't have problems at that speed - let alone you. Do not let the tug fly slower than 65 Knots with water!

 

WRT the rudder pedals no doubt that you've learned your CHAOTIC check since then. :)

 

 

[Exadios]

Heavier means turns less tight. Larger radius.. Nev

To be exact faster (i.e. increased speed) means less tight turns. But, of course, increased wing loading means a speed increase is necessary.

 

 

[Oscar]

Aft CoG is scary. And 50 Knots is too slow. I'm surprised that the tug didn't have problems at that speed - let alone you. Do not let the tug fly slower than 65 Knots with water!WRT the rudder pedals no doubt that you've learned your CHAOTIC check since then. :)

Yep, it was a new tuggie - a croppie who'd been roped in as one of the usual guys was off sick. And I think I was about his third customer ever! Nice bloke; I went over and asked him if the tug was having problems ( I had though it must have, flying so slowly, which is why when what looked like a wing-waggle happened, I bunged-off instantly. He said 'No, I thought you guys didn't like to go fast?' It was a Pawnee 235 and had been bloody hanging on the prop, going up like a kite with me behind like a paper-bag on a string. And the Hornet felt like I was trying to tap-dance on top of a ball-bearing, very not nice at all.

 

Yep, I knew my chaotic check, and thought I'd done it properly, but I wasn't aware of the peculiarities of the Glasfugel set-up. And, once strapped-in properly with no chute behind me, I couldn't actually reach the pull-handle for the pedals in the air, being somewhat of a short-ar$e in the arms department as well as the legs..

 

Fortunately , I had had some really GREAT instructors who had taken safety very seriously and put me (and every pilot in the Club) through the hoops!

 

 

[Exadios]

Yep, it was a new tuggie - a croppie who'd been roped in as one of the usual guys was off sick. And I think I was about his third customer ever! Nice bloke; I went over and asked him if the tug was having problems ( I had though it must have, flying so slowly, which is why when what looked like a wing-waggle happened, I bunged-off instantly. He said 'No, I thought you guys didn't like to go fast?' It was a Pawnee 235 and had been bloody hanging on the prop, going up like a kite with me behind like a paper-bag on a string. And the Hornet felt like I was trying to tap-dance on top of a ball-bearing, very not nice at all. Yep, I knew my chaotic check, and thought I'd done it properly, but I wasn't aware of the peculiarities of the Glasfugel set-up. And, once strapped-in properly with no chute behind me, I couldn't actually reach the pull-handle for the pedals in the air, being somewhat of a short-ar$e in the arms department as well as the legs..

 

Fortunately , I had had some really GREAT instructors who had taken safety very seriously and put me (and every pilot in the Club) through the hoops!

'C'. :)

 

 

[Exadios]

As far back as the original Discus most glider have had a tail tank. It is necessary because the water in the wings is in front of the spar and so forward of the CofG. If you add ~180l of water the CG moves a long way forward, still safe but detrimental to performance. The tail tank balances this out. When the tail tank is full there is a requirement to dump the water when the temperature gets to a certain value( i cant remember at the moment) lest the water freeze in the tail and cause structural damage. The small volume is prone to freezing before the main wing tanks. The temperature gauge is a required instrument if you use the water ballast.

The temp given in the manuals is usually 2 degrees C.

 

Some of the twins have a little more complex tail water ballast arrangements. For instance our club DG505 has two tail tanks - 'A' and 'B'. The 'A' tank is to compensate for the wing water as in the single. The 'B' tank is to compensate for the rear pilot. So the 'A' tank can be dumped but 'B' tank cannot - which is a shame because that implies that the rear pilot cannot be dumped either - ha ha.

 

The singles are arranged so that tail empties faster than the wings so that there's no possibility of getting the C of G too far back. In contrast the DG505 has a system of actuator interlocks. In this case the wing tanks cannot be dumped until the tail tap is opened - and once it is opened it cannot be closed from the cockpit. So, once the pilot decides to dump all the associated tail ballast is lost.