Freesteel Blog » 2013 » August
This was the formerly unlisted video of my crash down on the Gyrn in Wales which made me feel quite sorry for myself with my total lack of competence and ability to have a good time with this sport (skip to 2min 30).
Then I went to Austria and life was great, particularly at Greifenburg.
Things weren’t so bad back at Loser either, with a series of take-offs and landings that I loved — all of them.
Back home in Liverpool I wanted to fly some more, but haven’t had the chance. Got offered a dive trip out to Liverpool Bay yesterday, and persuaded Becka to come.
Pretty murky all told, but did the job of dropping us into a thoroughly different universe where we happily swam with the fishes in the dark until the air ran out.
What more could you ask for out of an experience?
We all know how rotten software patents are. Unfortunately, software companies are too often run by idiots who play the game by contributing to the worsening of the situation and doing absolutely nothing to make it any better.
Anyways, 19 months ago in March 2012 we got a press release:
Delcam will preview its new Vortex strategy for high-speed area clearance on stand 4011 at the MACH exhibition to be held in Birmingham from 16th to 20th April…
Vortex, for which Delcam has a patent pending, has been developed by the company specifically to gain the maximum benefit from solid carbide tooling, in particular those designs that can give deeper cuts by using the full flute length as the cutting surface. It can be used for two- and three-axis roughing, three-plus-two-axis area clearance and for rest machining based on stock models or reference toolpaths…
Unlike other high-speed roughing techniques that aim to maintain a constant theoretical metal-removal rate, the Vortex strategy produces toolpaths with a controlled engagement angle for the complete operation. This maintains the optimum cutting conditions for the entire toolpath that would normally be possible only for the straight-line moves. As a result, the cutting time will be shorter, while cutting will be undertaken at a more consistent volume-removal rate and feed rate, so protecting the machine.
Sounded a lot like the Adaptive Clearing strategy which I invented in 2004, and was most accurately replicated in 2009 by Mastercam.
Thursday, August 22nd, 2013 at 8:02 pm - Hang-glide
We walked up the Trisselwand one the morning. Even at 8am there was wind blowing around the shoulder where the thermal updrafts can always be found. I walked back down while Becka bribed Tom and Matt with lunch at Appelhaus for going on a longer walk. They both ordered roast gemse, and then it rained properly for the rest of the day.
I was left alone at base camp for a couple of days to work while more caving and detackling was happening at top camp. Due to a meeting in the afternoon I didn’t get off for my cycle tour round Grimming till 4pm.
First I went to the secret lake which cut through between the mountain and the rest of the range that I had discovered from the air.
Then there was a long stretch on a major highway to get to the eastern end of Grimming and round.
I arrived at bast camp at 9pm as it was getting pitch black after five hours at full speed the whole way on just one apple and two pieces of flapjack.
Today I flew for an hour while the others did the Via Ferrata on the Loser.
The clouds were low and I got into their turbulent sunny edge. It felt like the most natural place to be. Then I headed over to the Tristlevan, and the thermal was missing from the usual spot, so off I bombed, passing over base camp on the way. They saw me from there this time.
We’re driving home tomorrow to face the real world. There is some kind of crazy autumn and winter I have in store coming up. I don’t know what it is but I’d so much rather be flying.
Sometimes you get a feeling when you start an idea that you’re going to spend the rest of your life debugging it to make it work.
The idea behind Adaptive Clearing just worked the first time I implemented it. The theory behind it is fundamentally sound. Trajectories in 2D are unambiguous, and you know when they come close and cross.
Monday, August 19th, 2013 at 4:40 am - Hang-glide
As seen for two seconds over Grundlesee. (Is there another name for it?)
Another very good day. Day before was cancelled due to over the back wind creating an enormous rotor in the valley, according to the locals who said not to fly, because you can always save it for another day. (Did I ever.) It’s good advice to take local advice. They described for me a couple more thermal hot-spots to know about in the different valleys, the kind that haul you up to cloudbase at 3200m and set you on your way. I tested one of them out, and have it in the bag for next year. Cold hands again without gloves. I loved every minute of it.
Just to show willing, and because it’s not working out as effortlessly as I’d hoped, here are some notes on my approaches to five axis theory.
One classical approach is to create a 3-axis toolpath for a ball nosed cutter ignoring the shaft. Then work out a sequence of tilt angles at each point along the toolpath so that the shaft and holder doesn’t collide with the part. The actual cutting tool is invariant to the tilt because it’s a sphere. I made an adequate implementation of this last year.
Another common approach is to create a path in the part surface that is to be the tool contact point and then derive a tool position and tilt from this a la single surface machining. There’s a similarity between this and the first approach in that the fulcrum for the tilt is the contact point at the surface of the tool rather than at the centre of the ball.
I shouldn’t need to go into why deriving a toolpath from a sequence of contact points is an epic fail, having dispatched this as a viable option for all but the simplest, most unrepresentatively unrealistic, yet intuitively compelling cases back in 1994. It’s daleks and staircases. Folks who believe it can be done either haven’t personally tried to make it work, or, if they have made it work will most likely have debugged their code into a completely different algorithm.
Friday, August 16th, 2013 at 7:15 am - Hang-glide
I was going to do some 5-axis machining theory today, but the sky gods had other ideas. Way back at the start of expo I had this notion that, since you couldn’t expect to do much more than a maximum of three hours of flying in a day, it wasn’t going to disrupt things too much. But the fact is when you actually do fly like this for three hours with your head in the clouds, it’s hard to give a damn. I was flying like a demon today, and now I can’t make myself care about programming.
The Grimming is a crazy gnarly mountain on the south side of the valley as you go east from Bad Aussee which is the gateway to the Schladming valley and the tall side of the Dachstein. And I got above it, which is a dream come true.
There were enough thermals today for numpties to get to do awesome things with a lowish cloudbase at 2700m. Did I say I got to cloudbase? Five times. That’s more than all the times I got there in eight years of hang-gliding pre-1997 before I gave it up in frustration. That’s the power of this new GPS-powered thermal sat-nav. It’s a flight computer that says when you need it to:
“Hey, diptstick, you left the lift over here. Now get back and get into it, and stop fannying around like you think you know where you’re going — which is on the deck if you don’t get a grip right now.”
Flying over Grundlesee lake having finally got away from Loser. Grimming is that dark lump on the horizon I am looking at.
A view of Grimming from the cloud level before I dived for it’s left hand side, and nearly bombed out along its shocking southern face before I found lift all the way past on its right hand end.
This is the GoogleEarth track of that fly-by into the Enns Valley. One of the rules of successful XC flying is you don’t worry about the retrieve drive. While it is a short distance over the mountain range, the road goes the long way round. After getting up, I went back over Grimming to see the top.
It’s difficult to capture just how jagged the face of Grimming is. It’s all crumbly jagged pillars, like a Greek temple in ruins — except their pillars started out as pillars. Here it was solid rock at one time that looks like it was caught in a hailstorm of boulders. It was too easy to imagine screwing up round here and planting myself like a car crash in some inaccessible notch. For weeks the people of the valley would be able to look up in the sky and see this little patch of orange on their mountain, and nobody would ever be able to get it down.
At 3:30pm all the sailplanes around Austria began to converge on to me. I think their airfield was in the valley. There were stumpy ones, and sleek ones with white wings as skinny as helicopter blades. Their pilots were enclosed in comfy perspex bubbles.
Meanwhile, my hands were getting a little cold. I packed a pair of fingerless gloves down my front. When I got them out I realized they were a complete joke. Try putting on a tight pair of gloves while carrying a tea cup and saucer.
When I get home I’m going to make myself a pair of bar mitts. And get a harness that fits. This one is way too short and I hope I can do a lot more of this.
I looked up this area on the paragliding map, which is the finest application mash-up of meaningful, actionable geographic data I have ever seen, and go this orange spot denoting a thermal hot-spot.
The cool thing was I reached it all by myself without knowing about it. I think this was a lot of luck. In fact, the whole route was pretty jammy, according to the locals as they normally hop through the mountain ranges without taking that risky short-cut across the valley.
I got another flight off Loser today. One hour. This time among a gaggle of paraglider students on a partly overcast day.
The day started at 6:30am with a drive to the train station to pick up Tom, the latest back-up caver for the expedition. I brought him back to base camp for breakfast, drove him up the hill at 8:30am and walked him half-way to the cave along the path for someone else to collect him as I walked back to the car park to begin setting up for 11.
It’s all so routine now — even the diagonal run down the ramp to take account of cross wind. Lift was weak, but enough to take me up to 2100m before finally settling in for the long slow altitude decline as I tried and failed to get lift off every ledge and cliff forest on the way down. About five paragliders managed to cling on, so maybe its my lack of concentration that always hits me at the half hour point.
Whatever was going on, I eventually ended up here: across a forest, around a corner and above a lake.
Many years ago a friend of mine got to this place, missed the lake and landed in the very top of the trees. The Altaussee fire brigade had to fish her out.
Luckily, 3 minutes of gliding which burned through 200m of altitude got me 200m above the landing field, so a happy ending. I even landed on my feet. Still, I think it deserves a red mark.
Then a local paraglider friend showed me the path back up to the top of the hill to fetch my car. It was grueling. I’ve not recovered yet, but may have to do it again on the next flyable day as all of the cavers appear to be at top camp and not coming down.
Expo is small this year. Everyone is up the hill, except for me and Becka, and Becka isn’t with me at base camp because she has disappeared to a different caving expedition run by Austrians for the week. The weather has reverted to type, with several days of rain.
I’ve been working and programming for a change and my eyes are sore. A recap of some things.
In the last week of July when it was perfect flying weather I was at the 16th International Congress of Speleology in Brno.
It happens every four years and was a little too proto-scientific for me. I followed up every talk that had to do with data loggers and temperature sensors, and the general message is that nobody really knows what to do with the data. In particular, the Hoffman institute who collects lots of lovely data, and then stuffs it all into an excel spreadsheet with no idea what to do with it later.
In spite of the attendance by all the major contributors to the field, there was no scheduled workshop on cave surveying software. (Software is not real science, see?) So we had to invent one in a cafe at short notice.
Becka had a go at the speleo-oplympics and got scars from the chest tape on the 100m prussick (done in a T-shirt). Unfortunately it wasn’t a fair fight because a couple of Russian ladies who took this sort of thing a lot more seriously and probably trained throughout the year came along and cleaned up. People came out to see them race through the SRT obstacle course, which they did many times to get it right.
Then we got to expo. We’ve had the mid-expedition dinner. Got a visit from the deputy mayor of Bad Aussee for our 30th year of squatting in the same campsite every summer.
Yesterday we went canyonning in Strubklamm. Seems you can do a canyon too many times. I knew every corner off by heart. The jumps were good, although they didn’t seem to require the usual amount of dithering, standing on the edge, Will I? Won’t I? When do I go?
There’s kind of a decision-making protocol happening in your brain, with one part holding you back because it’s a silly pointless dangerous thing to do, and one part that eventually has the guts to over-ride it.
It’s like that with the hang-gliding. Except you can get sufficiently focussed on waiting for the moment when the wind is right that your guts are tricked into missing the moment. It needs to throw its veto in at the exact instant when you could simply step back, and this requires accurate timing as to when you higher brain is minded to be about to do something ridiculous. If the trigger for the action is external rather than internal, then it’s a little more tricky for it know when to step in react. It gets there too late when you’re already off.
It is exquisite magic that you can become a speck in the beautiful sky. Of course, it does not look like that when you are up there, because all you see is the ground around you looking down. The realities of where you feel and where you are are quite different. You’re in another dimension.
Meanwhile, I’m working through yet another half-baked idea on 5-axis machining, after all the other ones have failed. I’m getting far enough away from the usual approach that something might work. I do know now that it should not be done by (a) drive surface projection or (b) contact point driving, so it’s all about finding the alternatives.
Well, I got there. To cloudbase above Loser during 2 and a half hours of flying. It was quite hazy, so the pics don’t come out. Maybe I need a helmet where you can see me smile.
Here’s take-off, with the camera pointing backwards.
Sometime in the middle of the flight.
And in the landing field heroically unhooking.
I love these wings. Even in rough air they’re silk. After 20 years (give or take a hiatus) I now believe I know what coring a thermal actually means.
Cloudbase was reached at 3k ASL after four attempts popping off from the north cliff of Loser, which was a good result given the AlpTherm prediction of the day:
Afterwards I was beat. And the ground was so hot that I just lay there in the field beside my lovely glider.
Same time tomorrow.