Bernt

Actually, I'm willing to spend in the range of 800-1000 euros. Some sort of flash memory is a must for me (don't want to unintentionally record on top of other footage again , and hate the rewinding and fast forward related to instant playback...) For the AVC (I suppose it's the same as H.264?), what average encoded bit's per pixel do you consider to be ok in the skydiving environment? With the different HD modes of HD1000 the b/pix ranges from 0.19 to 0.33. A bit off topic perhaps, but would be great with a sticky with links to skydiving video samples taken with various cameras and various resolutions, fps etc.

Yup, I was a bit too fast with the searching, only searched for "HD1000" which gave no hits.

Can you say a bit more about what makes you think so? This cam has gotten fairly decent reviews over at Steves-digicam.com forum (considering the cam as a consumer cam) http://forums.steves-digicams.com/forums/view_topic.php?id=577679&forum_id=27&highlight=sanyo+hd1000+review What AVCHD cam would you recommend instead? (I'm not planning on going commercial with my footage, more for re-living the fun on dark winter days...)

Anyone using this one as skydive cam? Any problems? http://www.sanyo-dsc.com/english/products/vpc_hd1000/index.html

I think that should be Finnish big balls season 2007...

That's an expensive jump ticket, but must have been very naiis. About the g's, motorcycle helmets have about 300 g's as peak limit in tests. That's right, 300! For example, for the Snell M2000 test standard, the impact speed is 7.75m/s which is the end speed after about 3m free fall. The DOT standard even allows 400 g's peak, but _only_ 200 g's over 2/1000 of a second. The duration is really the key when talking about g's. 200 g's during 2 ms gives a displacement of about 4 mm (~0.16 inches). So that's about how much your brain will be compressed against the inside of your forehead if you put on a DOT helmet and jump head first from 3m onto a concrete floor... And a reference for non-believers: http://www.smf.org/standards/pdf/mstds_cmp.pdf

I was thinking that PC oscillation is a problem, and as far as I’ve understood, PC oscillation is believed to be a main cause for offheading when everything else is done right (good body position, no winds, good packing, canopy doesn’t snag on the tray). But you have a good point: How often does this actually lead to an offheading more than, say +/- 60 degrees? 1:100, 1:1000? I guess it’s a personal decision what odds are ok, if we’re ever able to say what the odds are. And I agree that cost and cost vs. added benefit may in practise be showstoppers, but we won’t know that before we know what the improved design is (if one exists). So why look for a new design if we don’t know how big of a problem PC oscillation actually is? How would we verify the new design? How many jumps would it take? How about all the other factors that affect heading? Sounds like we would need a lab set-up. A new design may introduce new unforeseen problems… But then again, how many of the modifications that have been done sofar are based on solid numbers? I think most of them are based on subjective observations and good ideas. I mean, how much evidence do we have that snagging on the corners of the pack tray is a problem? (With wingsuit, just arch before deployment. If you have head-down deployment, what are the odds of offheading more than +/- 60 degrees due to the canopy snagging on the corners?) But I like the _idea_ of dynamic corners. (no disrespect towards the manufacturers here, I think this a part of the sport) Anyone have an opinion of what the odds are that PC oscillation alone will result in an offheading of more than +/-60 degrees, using a vented ZP PC? Anyone who likes the idea of a PC less prone to oscillations?

I just don't get it… Why should we settle and believe that the PC cannot be improved?!? Of course, jumper skills are more important than improving the PC, but why not improve the PC if possible?? The parameters we have to play with are atleast these: Porosity of the topskin fabric (F-111/ZP), vents, diameter of topskin vs. diameter of mesh. We need some facts on the table, and I don't have enough jumps to know, so to you with experience on this: 1. At what airspeeds does the oscillation mostly occur? 0-2s? 2-4s? 4-7s? 7+s? Let's pick the corresponding size(s) PC and experiment with that one. 2. I think what Tom Aiello said about the drag of F-111 vs. ZP is very interesting. Anyone want to measure the drag at various windspeeds for similarly sized F-111 and vented ZP PC's? If F-111 really makes a more stable PC, then this would be one of the first things to find out.

Summarizing the discussion sofar, parts of the problem are: 1) PC inflation before PC is centered above the jumper 2) Air escaping from the sides of the PC, non-symmetrically. The 'forces' working on the PC are: 3) the weight of the main parachute tries to pull the PC towards the center 4) Air spilling from the sides of the PC tries to push the PC away from the center, if the PC is not in the center already, or non-symmetrically mounted/fabricated. I agree with you crwper that the mass of the PC is probably not the main cause. It has mass, so some effect yes, but I think the other forces are more dominant. It hasn't been mentioned yet, maybe it's common knowledge, but I realised not so long ago the the PC does not inflate before it is loaded, meaning not before bridle stretch. Until then it's just a piece of cloth... For 2), F111 and vents seem to help, since less air escapes from the sides of the PC. For 1), we can put a small slider on the PC so that it has time to stabilize in the center before it starts inflating… he,he, anyone who wants to try this? How about more vertical surface on the PC (increasing the drag for movement sideways), like on a tandem drogue, see the attached picture (looks more like an ice cone though…). Or would this have minimal effect? Could the next PC be F111, vented and with more vertical surface? Has anyone experimented with vented F111 PC's? Or is vents not giving any benefits here? Any problems with more vertical surface on a PC? Why is ZP used instead of F111? More durable? Bernt "If you jump from a bridge in Paris, you are in Seine"

I'm using the Observer (1m resolution), and I'm quite happy with it. The compass needs fairly frequent calibration though, it's a simple procedure, but it usually takes me a few attempts before it succeeds. As a sidenote, the resolution of the displayed altitude and the accuracy of the altitude estimate is two different things. Suunto refers to the 'resolution' in their specs. The accuracy of the altitude estimate depends on the air temperature and actual altitude.

Short version About the accuracy, one can easily mistake the accuracy of the display (often referred to as 'Altimeter resolution') as the accuracy of the altitude estimate, at least I did... Actually, the amount of meters the estimated altitude is off, is not just a single number, but depends on air temperature and altitude. I have the Suunto Observer, and as an example of it's altitude estimate accuracy: With 0 degrees celsius at sealevel and at 100m (I live in Finland…

Thanks for all the replies and concern!

Most people would probably agree that velcro rigs and wingsuits don't go together. Of course, the idea of having the velcro peel prematurely and getting a horse-shoe malfunction does not sound very tempting. But some time ago I read about one guy who actually uses this combination, and I know that a Medusa (velcro rig with tuck tab on the shrivel flap) has been used at least twice with a Skyflyer without any complications. Now the question is: When using a velcro rig with a wingsuit goes fine, is it just luck? Why/why not? Has for example the airflow over the rig been studied when flying a wingsuit? - Bernt