uer16

Members
 View Profile  See their activity

  • Content

    74

  • Joined

  • Last visited

    Never

  • Feedback

    0%

Posts posted by uer16

  1. Nothing (apart from limiting the amount you can carry, which the FAA does). I was just referring to the use of lipo batteries on safety critical stuff. I.e. APU battery on a 787, or in our case a battery on a riser. I'm sure it can be ok if done carefully, but it seems easier to just use more stable chemistries.

    In any case I don't know what they use so it's kinda pointless to speculate.

  2. Or even worse, during flight, which will instantly melt the riser in half and blind the pilot with sparks/fire :D. Hopefully we learned after B787 that lithium+aircraft=bad idea.

  6. We actually did this with a contactor (think big high-current relay) and a single 30 Ah 15C LiPo cell from our hybrid racecar. It was very underwhelming: it started off at 800 amps, it heat up itself and the 0AWG wires, then inflated, de-laminating the layers, then the current dropped off quickly to 0. A bit of smoke but that's it.

    What was a lot more impressive was poking one with a nail, we were glad that we did it in a blast shield. I highly recommend you do this at least once, I learned to respect these batteries and be more careful around them. Use a 5m long stick with a nail or screw at the end.

  9. pchapman


    You mean unimpressive now, or for initial production in 1991?



    Unimpressive now, as in if something like that was made in 2015, it would raise a few eyebrows. Modern tech would probably make newer AADs look a bit different.

    In any case, unimpressive doesn't mean bad in an application like this, less mystery is better.


    ..and how the hell did this get so far off topic :D
    edit: misread question

  10. Quote


    Like I said its closely guarded IP, similar to the recipe of Coke a Cola. Soif you knew all the criteria you would probably be the owner of Cypress



    Shouldn't be hard to dump the flash/rom and figure out the disassembly. What MCU does the cypres have anyway? Should be old enough to not have fancy crypto. Might even have JTAG which will marginally simplify stuff. Of course if they went with an ASIC (which I doubt, production volume too small), all bets are off.

    In any case, the "five other parameters" might include jumper orientation. Like adjusting for belly to earth or back to earth and such.

    Might also be the state machine accounting for order of operations (i.e, will only fire when you go constant->ascending->freefall, but not in other weird scenarios). You can even count timer ticks as a "parameter".

    Hell, they might have thrown a gyro and accelerometer to do some sensor fusion, would make sense for calculating orientation (don't know any other way to do it really). I'd love to get an out of date AAD and reverse engineer the hell out of it.

    Edit: found Dave's (from EEVBlog) teardown of a cypres, very interesting if anyone's curious (probably was linked here before, but I didn't find anything in search): https://www.youtube.com/watch?v=9-wzPTiLz5c. Uses some old Motorola ZC4 series along with a COTS analog pressure sensor and external ADC. Very unimpressive imho, which makes sense if you believe in KISS.
    Also not sure how they determine the orientation of jumper with only the one pressure sensor (or maybe that's the newer cypres?).

  14. So I was gear-checking my student rig that has b12s on legstraps, and noticed that the v-ring was put on reversed, putting all the load on the wrong side of the friction bar. It may or may not have been jumped like that.

    I'm curious as to how much strength loss occurs when it's misrigged like that, does anyone have any numbers? The v-ring in question is PS70113.

  15. Wow, didn't expect that many replies.
    First of all, thanks a lot for the input guys. Good to see that this community can give beginners some solid, legit advice :)
    Well, if boredom is such a big problem (didn't expect that) I'm probably gonna stick with something more conventional. Maybe s Storm to spice things up a bit. Anyways, I'm probably gonna speak to my instructor and more jumpers for more opinions on that matter, but it's already pretty clear where this is going..

  16. Just brainstorming here.
    Looking forward to buy my first rig this summer. I have decided that a very docile square 7-cell loaded at about +-.8 would be appropriate for me (I weigh 140 naked btw).

    I understand that this is a no-go for most of you. But apart from the (apparent) hard openings at terminal, what are the real dangers of doing so? In my opinion, there are lots of remedies to these hard openings: direct control, sail slider, primary stow, slidergate, tailgate, and it just goes on and on.. Yes, they may last less because of F111, but are easier to pack at the same time because of this. The chances of linetwists also decrease because of very low aspect ratio.

    Also, I am leaning towards CRW and maybe WS in the future, so a more-or-less appropriate canopy will help from the start.

    So I am asking you guys, what am I missing and why is this a bad idea? FYI, thought about a 190 Spectre at first, but now I am looking at a 200 Seven or a Flik with hybrid topskin.