750 in a Standard Libelle
by Col Vassarotti
"Where've you been the last few days - the soaring's been phenomenal!!". Somehow these words did not fill me with joy. For years I've been trying to fly a 750 kilometre task in Standard Libelle "Bravo Echo". It's been great fun and I've enjoyed many a long flight in the process. The magic and challenging 750, though, has always eluded me. In any glider, a 750 needs very favourable soaring conditions.
Libelles, of course, are not just any glider; but, like other standard class sailplanes of the late 1960s they are a little short of performance at the top end of the speed range. So, it's fair to say 750 success in a Libelle requires particularly good soaring weather.
These exceptional days do come along. The trick is to be there when they do. Then it's down to the pilot and glider being prepared, with the task declared to an official observer and the launch organised. Take off should be at the first sign of thermal activity. It all sounds easy. The problem is that those perfect soaring days have a habit of occurring when you are not at the airfield.
My perfect 750 day would feature light winds and reliable lift kicking off at about 1100 and going through to 2000. Realistically, thermal strength and depth would be low for the first hour, but compensated by rapidly improving conditions by 1230 or thereabouts. Such a dream day would deliver 5-6 knot thermals to 10000' (or better) from 1400 onwards. Clouds and cloud streeting would also be immensely helpful. This idyllic state would naturally prevail over the entire 750km flight route with no adverse weather changes such as thunderstorms, wind shifts or high cloud cover. As the pundits would say: "in your dreams Col..."
Canberra Gliding Club's Christmas camp for 1998/99 at Temora was great fun as always. The soaring was good, although short of outstanding. Over 6 days I managed 1200km of cross country in BE. Only one day looked a rough chance for 750. Unfortunately, despite an encouraging start at about 1100 conditions were very slow to improve. Lift strength was 3-4 knots at best and there were no clouds. North of Parkes the thermals deteriorated and I could not climb any higher than 3000' above the ground. As I had done on so many previous attempts I cut my losses and flew back to Temora; yet another nice long flight for the log book and very enjoyable, but not the elusive 750.
Predictably, as I prepared to drive home to Canberra on Sunday 3 January the sky looked magnificent. High, flat-based, well shaped cumulus clouds stretched horizon to horizon painted in sharp relief against the crisp blue of a fresh airmass: perfect soaring conditions. Temora airport was buzzing with excited glider pilots gleefully topping up their aircraft with water ballast and preparing for big flights. Morose thoughts of lost opportunities reduced my enjoyment of the drive back to Canberra.
I could hardly bring myself to look at the sky over the next few days. And there were big flights. Les Kinsley achieved Silver C, then Diamond Goal; Sue Hanley, Norm Sutton and Lou Szabolics flew their 500km Diamond Distance tasks. Rod Stone and his brother Ray flew a creditable 428km in the Puchacz only to be outdone by John Thomson and Stewart May who promptly covered 493km, also in the Puchacz. Rod was not too upset, though, because he succeeded in flying the coveted 750 in his Discus, 76. "It was such a good day Col" he told me enthusiastically (I didn't really want to know), "it was easy".
The news of all this achievement by Canberra pilots and others greeted me when I returned three long days later. With son Daniel's help I rigged BE on Wednesday evening. Was it possible, I wondered, the good weather might continue for just one more day? Thursday 7 January dawned with a clear sky, light northerly wind and rapidly mounting temperatures. Dan and I prepared the Libelle. John Thomson agreed to be my official observer. In the absence of any weather information I opted for a cross/downwind first leg and declared Urana, 150km to the south west as my first turn point. Second turn was Goonumbla 309km north, then Grong Grong 230km south as the third, with a 70km final leg back to Temora.
Dave Pietsch beat me to the launch point. He had declared 1000km in his elegant ASW 20 "Zulu Zulu". He took off at 1050 and disappeared rapidly northwards and downwards. The surface air was motionless with absolutely no sign of early morning thermals. The sky was dusty blue and cloudless. John Caldwell had just launched Dave behind the Pawnee. I questioned him intently. Had they encountered any lift on tow I wanted to know? John grinned. "Some bubbles" he said enigmatically. I waited another 15 minutes. There was still no movement in the surface air. I decided to launch anyway and took off at 1115.
After release I was relieved to find 1 - 1 1/2 knots lift going to 3000' above ground. I drifted towards Ganmain working between 1500 and 3000' and from one potential outlanding paddock to the next. Over the years I have accumulated a lot of practice at this nail-biting brand of flying. At times the time difference between the top of the climb respite and the adrenalin rush of circuit and outlanding can be 3 short minutes. This day the going was fairly easy and I was reasonably relaxed until Dave radioed that he thought he might outland at Barmedman. This did not sound good. There was better news 15 minutes later when he reported he was climbing again and back on track. By the time I reached Ganmain the lift was improving rapidly to about 4 knots and going to 5000'. Even better, cumulus were beginning to form, conveniently marking the thermals.
Conditions improved even more south of the Murrumbidgee with 5 knot average climbs to a 7000' cloud base. I photographed the turn point at Urana at 1330. At this stage I was slightly behind schedule but very encouraged by the even stronger lift and signs of cloud streeting ahead on track. The only worrying aspect was the high overcast which placed Urana and the entire countryside south in shadow. There were still cumulus underneath but they were smaller and less well defined. I hoped fervently this ghastliness would not follow me north. Urana to Forbes was very good. South of the Murrumbidgee was sensational with 8 knot average climbs to 12000' cloud base. I had switched on the oxygen before take off (more in hope than any real expectation of needing it). This paid off handsomely as I found it possible to make 20 - 30km glides between 10 and 12000' with a clear head and clear conscience.
By the time I reached Lake Cowal, cumulus were more scattered with bases about 9000', but conditions were still excellent. My confidence level was pretty high because I had made up lost time and was ahead of schedule. BE glides well at 75 - 80 knots with its maximum (albeit minuscule) 50kg of water ballast; but I had been pushing at 90 knots, sacrificing glide performance to take advantage of the good climb rates. At 70 knots the Libelle's natural sink rate is about 2.4 knots. At 90 knots airspeed this almost doubles to 4.7 knots down. The greater distance between the clouds and their lower bases meant that flying at this speed reduced my working height band from a luxurious 7 - 12000' to a less comfortable 5 - 8000' (4 - 7000 AGL). This worked nicely until I approached the Lachlan River.
About 15km west of Forbes a couple of clouds didn't produce lift. I pushed on and lo and behold found myself at 1500' above a group of stubble paddocks 2km west of the Gunning Range. So much for only taking 8 knot thermals - now I was scratching in zero sink waiting for a thermal to kick off. After 10 minutes of this frustrating and sweaty activity I contacted a respectable 4 knots and clambered back to 6000' . Keen to make up lost time I said good-bye to my 4 knots and pushed on to the next cloud. Within 3 minutes I was down to 4000' ; but, most importantly, nicely centered in an 8 knot thermal. Abeam Parkes I nervously watched the altimeter unwind yet again to 4000' . Only last week I had reached almost this identical point from Temora and encountered very poor lift. On that occasion I was grateful just to stay airborne and struggle back south to better conditions.
Luckily history did not repeat itself. I hit a booming thermal which I managed to centre from the very first turn. The Cambridge variometer pegged at 10 knots, the instrument's maximum. Out of curiosity I timed the rate of climb by stop watch: a genuine 12 knot thermal to 9000'. At about 6000' I was joined by a two-seater - a K13 or a Bergfalke, I think. It climbed well but the pilots must have been impressed at the rate BE rocketed upwards. Reaching cloud base I left the thermal to the two-seater about 2000' below and zeroed in on Goonumbla, first silo north of Parkes. At 1620 I took the turn point photograph. Next leg was to Grong Grong. The sky looked great. The 309km second leg had been completed at 109 kph. I relished the prospect of the higher cloud base and cloud streeting which I had enjoyed earlier between the Murrumbidgee and the Lachlan.
And it was good. At least it was good until I was within sight of Ariah Park. The GPS told me I had 85km to run to reach Grong Grong. Temora was a further 70km. It was 1730. It all seemed easily achievable. I could almost taste the cold beer at Temora, maybe less than 2 hours away. Ominously, the sky was not looking so benign. That high cloud I had seen near Urana was now much further north. The ground from Mt. Beckham to the southern horizon was in shadow. The only cumulus were thin, scrappy and altogether unimpressive. I was looking at a clearly decaying sky. "Stay high, stay high" I told myself.
At the last of the good cumulus I wound up to cloud base at 9000' about 15km north of Ariah Park and started a cautious 70 knot glide into the gathering gloom. 7000' on the clock and still 60km to Grong Grong. "Not good" I thought. Over to the south west there was an isolated well-shaped cumulus. It was mid-way between my present position and Narrandera. Diverting to it meant going at least 15km west of track. On the plus side, it held the prospect of a good climb to 9000' . To glide directly to Grong Grong from my present position meant arriving there with zero height unless I found lift along the way. There had been none since I started my glide north of Ariah Park.
I heard Ziggy Kominek at The Rock in the Jantar CQT. He was at 7000' and said it was heavily overcast and dark and thought he was unlikely to make it back to Temora. Dark, I'll say it was dark! I looked over towards The Rock, such a prominent landmark that it can usually be seen from the air for well over 100km. It was invisible. (I heard later that when Ziggy took his turnpoint photo the camera flash went off!). Following Ziggy's example I called Canberra base at Temora and admitted I was not too confident I would make it back. Stewart May offered helpful advice to Daniel at this point. Taking account of Dan's inexperience at glider retrieves (or even towing the trailer), Stewart gestured vaguely towards the south west and said "Grong Grong is that way". While all this was going on I made my decision to divert towards the solitary cumulus and arrived there at 5000', still no closer to Grong Grong. The rate of sink increased as the Libelle slid quietly into its shadow. I held my breath. Joy abounding! BE surged upwards in a 7 knot thermal which I rode to 9000'.
Now I had enough height to reach Grong Grong with sufficient to spare for at least the first 10km of the 70 between Grong Grong and Temora. The turn point was very difficult to see. The entire area was in shadow from the overcast although there were patches of filtered sunlight which dappled the ground in places. Looking at the ground I was intrigued and encouraged to see long plumes of dust blowing horizontally from the south and streaming upwards. Optimistically, I thought I might get some assistance from a tail wind on the home run to Temora. Down to 3000' above ground after turning Grong Grong I dumped the water ballast while working a miserable half knot of lift. The climb rate improved to 2 knots. "Good", I thought "if I can just get another 3000' I can make final glide." Perversely, the late evening thermal quit after just 1000' .
The air was very still. Temora remained out of reach. Suddenly it happened! BE bucked, pitched and rolled in turbulence just like the rotor we are all so familiar with at Bunyan. The vario screamed up to 7 knots and instantaneously sagged to 10 knots down. It felt like flying inside a gigantic tumble dryer. The southerly air flow seemed to have formed a convergence zone with the upper north westerly stream. Wave and rotor flying techniques worked nicely. Elongated turns, pushing into the best lift and very tight turns in the strongest lift zone meant I climbed at 7 glorious knots for about 2000' . Then it all stopped. But now I had 7000' - more than enough for a comfortable and very satisfying glide to Temora. I landed at 2005. Now, that's what I call an outstanding day.
Epilogue: Ziggy made it home too for his 750. Bruce Campbell (Cirrus) and Garry Stevenson (Libelle) also flew 750. They showed better judgement than Ziggy and I by tasking in the sector west and north of Temora - away from the southerly overcast. Dave called off his 1000km attempt after initial slow progress. He still managed more than 800km. Sue Hanley completed 500km in her Astir IKI.
It rained the next day.
