Matevz13

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Posts posted by Matevz13

  2. benlangfeld

    That's exactly my point. Wing loading as strictly defined (at least the definition I see, which apparently is not the common usage) doesn't change, because it's defined as a function of mass. A manoeuvre introduces a component of acceleration, which does not alter mass, but does alter weight. It therefore does not alter wing loading per the strict definition.

    If your argument is that the definition on wikipedia is wrong, then I'll propose a fix to it and correct my understanding. Indeed John LeBlanc states the definition as a function of weight. Which is correct?

    If it's that the existing definition is indeed correct for aerodynamics in general but not useful to parachuting, then that's cool, but maybe we should have a distinct term with a different definition to avoid confusion.

    It may seem pedantic, but bad things happen when we think we're talking about the same thing but we're actually not: https://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_failure.



    Hay,
    all I am saying is that you can´t just equalize mass with load and that if Wing loading is defined as wikipedia is saying, naming of it - "Wing loading" is not really most accurate.

  3. benlangfeld

    Quote

    The assumption is correct, spiraling, by increasing the G-Number, will in fact increase the wing loading experienced by the canopy for the duration of the maneuver.



    So do you suggest Wikipedia be corrected? From https://en.wikipedia.org/wiki/Wing_loading

    ***In aerodynamics, wing loading is the total mass of an aircraft divided by the area of its wing.




    I believe I’m still correct in that the wing loading is not changed, being defined as a function of mass. One’s load factor (https://en.wikipedia.org/wiki/Load_factor_(aeronautics)) changes, and the impact on fight characteristics might be the same as an increased wing loading, but going full pedant, the two are not the same.

    Just a thought.. load or force can not be interpreted as a mass. For force or load we need to multiply mass with acceleration. And acceleration will be bigger or smaller - depending on maneuver preformed with canopy. So in theory wing loading is changing all the time.

  4. the.Legend

    I think that you misunderstood my comments. After all we're talking about some of possible scenarios with smaller probability of occurrence than when other safety system work correctly. As you mentioned, in posts above people already pointed out the most obvious flaws. What I'm mere suggesting is the things I'd pay attention to if I were to design this product.

    1) Let's assume that you have two-out for whatever reason. Also let's assume that one of main's line got wrapped around that piece where camera attaches to the plate (blue line in original attachment). Even if you cut away either camera or canopy or both you still have a line with two-sided hook tied to it. Because camera and hook plate are inseparable now. This situation is rather dangerous, don't you agree?

    2) Ease of installation is quite a big factor. Imagine that you bought an iPhone and the charger that goes with it actually consists of two wire pieces and every customer must solder them together to make it work. Pretty simple operation if you ask me. But would it be convenient for you as a customer?
    While it might not be an obstacle for some, it might be a deciding factor for others, so you're loosing customers.
    Yes, there are many similar products on the market, which foresee drilling holes. And others don't. If I had to choose between this and GrellFAB Front Mount I'd choose the latter because it works right out the box.

    3) Ok, I might be exaggerating about head injury by two bolts.

    4) As you may already know in skydiving nothing "unlikely" is impossible. In this very thread there was a mentioning of line got caught under grommet. How "unlikely" is that? With these springs I assume the scenario when you cut away the camera, don't cut away main, spring catches the line and while canopy is stalled or simply other lines aren't stretched yet it snags another line. While I agree this is a border-line scenario, its possibility still above zero.

    I genuinely wish people to design this product and stand out from their competitors.



    Hello,
    at first I must say that cutaway works so that after pulling a cable nothing will be on helmet anymore.
    When you will pull the cable springs will fly away from the force stored in them (they are also really small and light).

    We also agree that ease of installation is big factor, but we supposed, that those who will buy our product and do something to be safer they will take this into consideration - we really think that after cutaway nothing should stay on the helmet and we didn't found a way to do that in any other way than to drill into the helmet.

    I must just say, that after all the comments and all the constructive criticism we ''went back to the drawing board'' and made quite some changes to the shape of the mount. My college will write post about that shortly and then we can say something more about everything.

    Greetings,
    Matevž

  5. councilman24

    Take your mount and hang it on a wall sideways. Now hang your bath robe on it. If it stays its wrong. If it was wider at the helmet instead of the camera then your robe would fall off. Or do it this way. Wrap a bridle around it 360 degrees and see if it comes off cleanly. If your mount looked like a cone instead if a funnel it would. As it is I expect if you don't allow the helmet to rotate you can pull on it until your pins fail. Also the gaps between the camer and the mount should be a small as possible, ideally smaller than a line. Snags can come from all directions.

    IF it was wider on the bottom it would be harder to fit to the curve of multiple helmets. An idea I thought of was varying flexible gaskets to fit between the mount and helmet.



    At firs thank you for constructive criticism.
    We will try test you described first thing, when we will get new prototypes and will post photos of it.
    Base of mount is already wider than camera for 13mm. Do you think that is not enough?
    We are already putting thin layer of rubber between mount and helmet for better fit.

    Greetings

  6. mr2mk1g

    That almost looks worse than the stock mount.

    Try hanging 800lb (a light guy with gear pulling just 4 G) from the mount and see if those pins lock the cutaway cable from being able to release. Then try it with 1600lb.



    Hello,
    pins are designed that they will brake from overload at 77lbs (that is the upper limit). When mount is exposed to force of 70lbs force required to pull out the cable is 20lbs. We have tested thise deferente scenarios quite alot.

    Greetings

  7. obelixtim

    Think again.

    That looks dangerous. Not suitable for skydiving. Did you actually think about it, or ask any experienced camera flyers for advice?

    I've seen lines catch on things a lot less snaggy than that.

    No way would I be happy with anyone jumping that on any DZ I was responsible for.

    Are you or your buddy even skydivers? Your profiles don't indicate so. And your previous comments regarding why it won't break, or losing your helmet, indicate to me you don't understand why that might be a good thing.



    Hello,
    could you please explain why you think it is dangerous and not suitable for skydiving?
    And yes since we are not very experienced skydivers (we both are skydivers) we have been working with much more experienced skydivers. We also know that design as it is on the pictures isn't ideal and we have already changed it as explained in previous replays.

    Greetings

  8. Quote


    It looks like it is designed to create a snag hazard.

    It looks like the release wire would be inside the helmet.

    How does it release from an overload?



    Hello,
    as I explained in previous reply the design on the pictures isn't final and design is already changed so it doesn't have any gaps between camera and mount.

    Yes release wire is inside the helmet - between helmet and padding.

    Release mechanism is designed so that the pins holding the wire are the weakest members of the structure and they break when you put enough load on them.

  9. councilman24

    Why in the world do you try to protect the GoPro from snagging lines with something that looks a whole lot like a coat hook? Tangles are rarely neat and vertical. Expect or to hook things from any angle. Itr doesn't mater that a line oulled straight up slides off. Pull a line or bridle sideways and see what happens. Make the damn base wider than the go pro so that things tend to slide off instead of hang up. And make the gaps as small as possible. THEN your cutaway system would need to work much less often.

    When I was making a custom video mount with a hack saw, file and drill I made sure there were NO corners that something could get caught under from any direction. With something the size of a film slr, 1980's video camera and a newton ring sight you could be perfect but better than this. Sorry to be so blunt but there was another guy a few months ago who just couldn't understand it should wide at the helmet and taper around the camera.

    Btw darken the text and lighten the photos. Very hard to read some of tbe text against the dense photos.



    Hello,
    at firs I would like to say that we rally are thankful for the comment, since more people always know more.
    I must say, that the mount on the pictures is prototype, that was made to fit all different models of GoPros and was meant for testing mechanical specifications. As we said the mount is still developing and will be available at the end of February.
    We have already minimised the gap between the mount and GoPro to 0,1 mm and made mount wider, so it is wider than the camera.
    I will post some pictures as soon as possible.

    Greetings