jmidgley

Hi It's a Canon MV5iMC - called an Elura Somethingorother in the US. Yeah, I know, get a Sony. On the other hand, I already own this camera, whereas I'll have to buy a Sony. I might just do that anyway, maybe off Ebay, just as soon as I figure out which PC model I want - there's so many of them. John

Hi Is it possible to get a decent wide angle lens for a video camera with a 28mm thread? Or is it usual to cobble something together with a 28mm to something-elsemm adapter? Cheers John

Tough to finger trap? Nah. You should see this stuff I've got for making parafoil kite lines - like a spider's web. 1000lb Spectra (which I also use as closing loop material) is fairly large stuff. For the few times I need a fid, I just use a fine piece of wire from a hobby store folded in half - I could epoxy it into a handle, but I'm lazy. You can make a continuous loop with no external fraying ends by pulling each end into the core. Pull one end in going one way, then right next to that entry point pull the other end in going the other way. Does that make sense? John

Hi I've tried to watch the video, but for some reason I only get to see a selection of random 'stills' as the progress bar moves along. Frustrating. From what I can make out of the site, it looks like a pretty vertical cliff (wouldn't make a very good base exit point otherwise, I suppose!). From your description, it slopes away on the other side of the ridge. This would make it a poor choice for going 'over the back' on ridge lift alone. The rotor would have you slapped into the ground behind the edge. A paraglider pilot would consider going over the back if they have gained a significant amount of height in a thermal, in addition to the height gained purely from ridge lift. A rule of thumb I use (but I don't claim any great science behind it) is to fly only as far back as allows you to still get 'line-of-sight' on the slope of the thing you're soaring. So if it's a gentle-ish slope, you can afford to drift back from the edge a bit, so long as you can still see the slope. But if you're flying a cliff and the cliff face disappears from view...get forward! At the risk of stating the bleeding obvious, the ease with which you can observe the rule above, and still maintain any manoevreability along the ridge gives you a good indication of your wind-speed safety margin. If you can boat up and down the ridge, only pointing pointing slightly outwards, all is well. When it gets to the point where you're hanging stationary pointing into wind, you only need the wind to pick up a fraction more and you're toast. Ideally, be aware of the potential for a gradual change from scenario A to scenario B! Cheers John

Thanks all I'll do a bit more digging about Lillo - sounds ideal. John Which 'cheapies' fly to Madrid?

Hi I like Empuriabrava - I've been there seven times. The only people who are there more than me are the students of Warwick Uni, who appear to live there. However, I'm getting a bit fed up with sitting around waiting for the tramontana to disappear. Last time I went (in November last year) 9 out of 10 days were blown out; previous March was almost, but not quite, as bad. Also, I feel I ought to get about a bit more. Are there any other DZs in Europe that turn around lifts like EB does when it's going well? With reasonable airport proximity? Frankly, I can live without nightlife for the duration of a long weekend. Just so long as I can hear the magic words at the end of the day "Boarding call, Twin Otter load 37..." John

Aha! Thanks. I imagine that there's some research somewhere behind those figures - unless they plucked them out of the air... Regards John

Mmmm... Assuming a vertical descent onto solid flat ground, such as might be experienced by someone under a round non-driven reserve, or someone stepping off a wall. In the latter case (unless it's an awfully high wall) the subject would be accelerating, but given the height of the wall it's easy enough to work out the speed at the moment of impact. In ideal conditions, the reserve would have a fixed descent rate. So the question is, is there some received wisdom (from the military, say) about the likelihood of injury or death as speeds increase. I'm thinking of something like[1]: 10 feet per second (equivalent to 1.5' wall)- no injury 16 fps (4' wall) - small proportion minor injury 20 fps (5'9" wall) - large prop minor injury 32 fps (16' wall) - dead as a door nail The 'impact' goes up with the square of the speed too, I'm sure. Anyway, that's the kind of thing I'm after. John [1] Numbers illustrative only!

Can anyone settle a debate with some facts? I'm looking for some data on likely injury/surviveability with increasing vertical descent rate. Of course if the data supported my position, that would be fine, but I'll protect the last vestiges of my intellectual honesty by not saying what that position is... Regards John Midgley

Hi I think the one you're talking about is the Bernina 217. There are 2 versions - I think the 217N takes cams and the 217 doesn't. If you find 2, I'll have one - been looking forever. John

I've had a 170 Sabre2 for 27 jumps now, loaded at about 1.25. Control is predictable and progressive, landings are perfectly straightforward and don't require perfect timing. It seems to retain enough energy to recover from an over-enthusiastic initial flare, allowing you to just hold the brakes and finish the flare later. You can stooge about conservatively or fling it around like a madman. It seems to be very stable and will return to the S+L without positive input. There are suggestions about systematic off-heading openings, but I've had none that I wouldn't put down to bad packing/poor body position. I'm glad I bought one! ------------------ Now had this canopy a little over 100 jumps. It's my low-timer view that consistent packing and deployment are rewarded by consistent openings. Once it's open, it flies like a dream. At full throttle it moves fast; in deep brakes you can hang around for ages. Stall is signalled well in advance, and recovers quickly when you return to half-ish brakes. Front riser pressure builds very quickly in turns, to the point where you're doing one-arm pull ups. All that positive pitch pressure means it returns to the straight and level very quickly once you let go. It's always proved very easy to land, even when the pattern sets up downwind! I don't have a lot of experience of skydiving canopies of this sort, but it seems fairly insensitive to harness (as opposed to brake) input, requiring a significant effort to steer 'no hands' (by comparison with a paragliding canopy). Certainly no regrets 100 jumps in.

I can't compare them, since I've never been to the other DZ you mention, but I did my AFF at Empuriabrava, and have been back there 5 times in 2 years. From AFF upwards, they have excellent coaching available (I did Skydive U there, and more recently had FF coaching from Babylon). The facilities are excellent, the staff are friendly (especially the manifest girls, even after the thousandth stupid question of the day!). Empuriabrava itself has plenty going on. Disadvantage is the Tramontana, a local wind which effectively halts skydiving, possibly for days at a time. Hire a motorbike, catch up on your reading/sleeping/drinking, visit the Dali museum in Figueras, go skiing; don't do what I do and sit at the DZ! John

Can't quite tell; did he go stowed?

Hi Following a conversation with a rigger who's opinion I value, I determined that my kill line was right on the verge of being too short - at full 'cock', the apex tapes were at the same tension as the kill line. I replaced the kill line, and now always cock the chute, not by pulling on the hacky, but by reaching in at the base of the PC and pulling the kill line through the bridle. This serves two purposes - since I dont have a window either, it allows me to see by glancing through the mesh, right up until the moment I put the PC in the pouch, that there's a bend in the kill line when the apex tapes are taut and therefore the chute is cocked. It also prevents kill line shrinkage creeping up on me un-noticed, since I see it every pack job. In your case I suppose it might have the collateral benefit of allowing an inch or so of 'creep' before it starts to affect the PC - it also saves that thing I hate to see; people HEAVING on the hacky, trying to wring every last millimetre of kill line out, when by just a gentle tug at the kill line itself, you can leave the stitching on the hack unmolested for when you need it... Now you can all queue up and tell me why no one else does this, and why it's going to kill me. Regards John

Take any object that glides. If it's possible to alter it's speed, it will have a lowest speed (at which it stalls) and a maximum speed (which might be a design limit, or imposed by drag, or simpy 'no brakes' in the case of ram air canopies - ignoring strategies for deforming the leading edge). At each of these speeds the glider will sink at a certain rate (the numbers change for different wing-loadings, of course). At each speed in between, having settled to that speed, the glider will sink at a certain rate. If you plot all those speed/sink rate points, you get a polar curve, which looks like a lop-sided, upside down 'U'. At one point, not far from stalling speed on a ram -air, you'll find 'minimum sink'. Well worth finding this point. Further along the curve (ie faster) you'll find a point where the distance covered is maximised with respect to the sink rate - 'maximum glide'. It may not be with brakes fully up, but probably quite close. Any faster and you'll cover *less* ground. Figures like '50%' are going to be impossible to judge in practice, but if 'min sink' happens to be a surviveable descent rate, PLF or otherwise, it would be as well to get a feel for where it is on your canopy. Don't know whether that answers your q, but hey. John

Aw. You guys, you guys. Thanks. Funny everyone should latch onto sewing canopies - I never mentioned that! But I suppose that the same consequence arises - having bought it for whatever original application, the temptation is, since you've got 1000's of metres of the damned stuff, you use it for everything. 'E' and '#69' as specifiers seem to be completely unknown in England, but M40 appears to buy the same stuff. Now, onto the differences between different kinds of string... Regards John

Hi Just curious - why nylon rather than polyester thread? Mechanical properties? UV resistance? Cost? There's bound to be a good reason... Regards John

Hey, hey mate; what's wrong with hang gliding?! The nearest to aviation heaven it's possible to get. Us HG pilots (well, OK, me) think you should try before you diss... I've always imagined that standing on an exit point, PC in hand, would capture some of the thrill of standing on an alpine ramp like St Hilaire de Touvet (~ 2000' vertical?) or Plan Praz (? the one outside the cable car station above Chamonix, anyway), watching the streamers, waiting for them to start twitching..... 321 bon vol! Regards John M

I've had one for 90 or so jumps, ever since I lost a protrack off the side of a Gath... The sizes are bizarre - my normal size head is 'XXL', apparently. Unlike other correspondents, I can't feel the protrack. I've stitched the chin strap, as it tended to wander slightly in use. Older models were notorious for cracking around the chin strap rivets, but the new shells don't seem to do this. I'll buy a new helmet when I get a camera, I think, but keep this for occasional use. John

Hi I've done this very trip a number of times. I stick the rig in an anonymous-looking rucksack who's external dimensions fall within the published limits. Don't volunteer anything to anyone. You haven't seen me, right? Having said that, I went with a chap who just put the rig on his back, leg straps and hardware dangling - he just sauntered on! John

Hi Taking the other tack (geddit?), if you literally mean just learning the mechanics of sewing, then an ordinary 'domestic' would be a great idea. They go for peanuts 2nd hand, and have often led an easy life. I picked up a Pfaff 1471 for a song, and it's amazingly strong. It will push a 110 needle (#18 size?) and 'E' thread through 6-8 layers of denim weight cloth if I take it at a run. It also has a kind of Pfaff-special walking foot arrangement called IDF, which helps to keep two layers of cloth aligned, particularly slippery stuff like rip-stop. I'm working on the basis that I'll probably kill it in the end - I'm looking out for a Singer 20U or such like, but in the meantime it's nice to have facilities like needle down (where the machine always stops with the needle in the cloth) and multi-step zig-zag. Regards John

If I might... At good (i.e. low) glide angles, such as attained by high performance gliders, the hypotenuse can be used as a proxy for the adjacent side, without introducing much error - in other words the aircraft's airspeed can be used as a proxy for the distance covered horizontally (assuming still air). At the atrocious glide angles attained by skydiving canopies and worse, by human beans, this is no longer the case - you have to work with the actual distance covered horizontally and the sink rate. At a 'real' glide angle of 1:1 (45deg) if you were falling at, say, 80mph (and achieving a horizontal speed of 80mph) your airspeed would be 113mph-ish. HTH, HAND. John

I pay for packjobs in Empuria because a) I'm on holiday and b) I'm on another load in 10 minutes. I pack for myself in England mostly because it's rare that I'm going to be jumping again inside an hour, so it seems a bit daft to pay someone, just to sit around bored! Also £5 vs. 4.5 euros... John

Yeah I could have been a bit more specific, couldn't I? Especially if you've had both: I've been on the lookout for a used 20U, without success so far. I have had an opportunity to briefly play with one, and I wasn't *that* wowed with it's grunt (appreciating that it's more 'artisan' than industrial). How does the Bernina compare? I understand that *some* of them can be fitted with cams to give you things like 2- or 3-step zigzag, but I don't know how universal that is. So, just impressions of it's quality, likely longevity, maybe even how much to pay...? Regards John

Hi Does anyone have any experience of this machine, as an alternative to the ubiquitous Singer 20U? Regards John