That should read: "...by the switches or was the air flow non-laminar ?"
On Mon, May 23, 2016 at 11:30 PM, w9ya <[email protected]> wrote: > Hi Chris; > > Hmmm..... well the logical question is did the two holes on either > side if the camera shroud ever function correctly ? i.e. Were they > occluded in any way by the switches or was the air pressure > non-laminar ? If so, then you really only had two holes total; one of > which could have been momentarily blocked. > > Best regards; > > Bob Finch > > > > On Mon, May 23, 2016 at 10:01 AM, Chris Attebery > <[email protected]> wrote: >> Hi Bob, >> >> There were 4x 1/4" holes in the altimeter bay. One on each side of the >> camera shroud for the screw switches and two more spaced 120 degrees from >> the center line of the camera shroud. >> >> My theory is that the camera shroud caused some sort of pressure wave after >> it hit mach. The pressure doesn't seem to change from 3.5 seconds until 5 >> seconds even though the rocket is traveling ~1100ft/sec. Then a quarter >> second after it passes back though mach at ~5.25 seconds there is a pressure >> spike. There is another pressure spike at ~6.5 seconds and that is when >> everything went down hill. >> >> You're required to use redundant electronics for your L3 flight. Next time >> I'll use something that is accelerometer based so I don't have to worry >> about these issues. >> >> BTW: I figured out how to use the zoom functions in AltOS last night after I >> posted this. I took a snapshot of the portion of the data relevant to this >> discussion. >> >> On Mon, May 23, 2016 at 8:23 AM, w9ya <[email protected]> wrote: >>> >>> Um..... I like to have THREE pressure ports....i.e. just in case. >>> Here's how (and why): >>> >>> It seems that this flight qualified as a "just in case" scenario. I >>> generally make each hole .67-1.0 the size of the specified size of the >>> single hole specification, all of them the same actual size, and space >>> them equally around the circumference of the body. The idea being that >>> while one hole can/may be "blocked" to incoming air pressure, blocking >>> two of the three holes should not happen. >>> >>> I am guessing the hole located near the camera shroud was the problem. >>> >>> Best regards; >>> >>> Bob Finch >>> >>> P.S.... I am big fan of backup electronics but I almost never actually >>> use more than one altimeter for deployment. Good electronic bay >>> modelling along with good electronics seems to negate the need for me. >>> >>> On Mon, May 23, 2016 at 12:48 AM, Keith Packard <[email protected]> wrote: >>> > Chris Attebery <[email protected]> writes: >>> > >>> >> I've attached a rendering of the altimeter bay and camera shroud. In >>> >> hindsight I should have sealed the camera in a separate bay from the >>> >> altimeters. I would probably stretch the rocket a bit more to get some >>> >> separation between the electronic and the camera shroud. I need to look >>> >> into getting a second accelerometer based altimeter for backup too. >>> > >>> > Hrm. Thinking about this some more, is it possible that the rocket went >>> > sideways? It's really hard to make an ebay airtight enough so that a >>> > plugged static port would read a steady, and even increasing pressure >>> > while the rocket was still going up. If there was some major structure >>> > failure near motor burn out, I would have expected to see more noise in >>> > the acceleration data though, so it would have had to be a fairly gentle >>> > failure mode. >>> > >>> > -- >>> > -keith >>> > >>> > _______________________________________________ >>> > altusmetrum mailing list >>> > [email protected] >>> > http://lists.gag.com/mailman/listinfo/altusmetrum >>> > >>> _______________________________________________ >>> altusmetrum mailing list >>> [email protected] >>> http://lists.gag.com/mailman/listinfo/altusmetrum >> >> _______________________________________________ altusmetrum mailing list [email protected] http://lists.gag.com/mailman/listinfo/altusmetrum
