Here are minutes of our meeting on Thursday -- please just reply with (or let me know) any corrections -- thanks!:
Attendees: Yorke Brown (Dartmouth), Arnold Gaertner (NRC), Konstantin Baibakov (USherbrooke), Karun Thanjavur (UVic), Susana Deustua (STScI), Cordell Grant and Houman Hakima (UTIAS-SFL).
Yorke, Cynthia, Maggie, and I did a set of three tethered balloon drop tests early this Saturday (May 9) morning at Garipay Field in Hanover, to test Yorke's new parafoil rigging scheme (and secondarily to check the manual operation of the controllable helium bleed valve we'd like to have on future balloon flights). We used the dummy payload (just a 6 lb. weight shaped like the regular payload, with no radio or any equipment onboard) as the test payload. Photos of the tests can be found on the regular ALTAIR Shutterfly site, at https://altairphotos.shutterfly.com/pictures/282 , and the videos can be found at https://particle.phys.uvic.ca/~jalbert/TetheredBalloonDropTests_9May2015/ (FYI in order to upload the videos to our Shutterfly site in addition to photos, we'd need to upgrade to the Premium Shutterfly service -- $$ that I'd prefer not spending). The tests were mildly successful, although not perfect: as one can see from the videos, the parafoil opened nearly all the way (~95%) each time, but not 100% completely; it would provide a perfectly fine parachute in that state, although steering might potentially be compromised. (Note that with a drop from free-flight at a significantly higher altitude, it is certainly possible that the last ~5% of the parafoil would open.) On the last of the three drop tests, an annoyance happened -- the descending parafoil became caught on the tether line and as a result, 6 of the parafoil's 48 strings got sliced as a result of the dynamic friction between them and the tether on the descent. We are currently splicing new strings to fix those 6 strings. Such a fix has successful precedent: when the ALTAIR12 flight ended in a tree, and the arborist service (Chippers) retrieved it for us, some of the parafoil strings were sliced, and were successfully repaired via knotted splices as well. We should have that fix completed by tomorrow. Future tethered drop tests will be via two very widely-spaced tethers, rather than a single tether, to avoid this happening again. The test of the manual operation of the helium bleed valve http://www.grainger.com/product/VALTERRA-Gate-Valve-4HGE8 (to be automated as http://projectaltair.org/HyperNews/get/AUX/2015/04/26/21.12-18702-balloonvalve3.jpg) was a complete success -- with the valve fully opened, the balloon appears to deflate from a kg or so of lift to a zero-buoyancy state on the order of a minute or two, which is perfect, not too slow (like the one in the writeup from which we got the idea http://www.benoxley.com/b/altitude_controller_report.pdf) nor too fast (if it drained in a few seconds then the valve would be too difficult to control). Yorke has started making the automation per the above drawing for that, and will likely complete that (plus a lip to keep the balloon firmly attached to the valve, so that we can then mount the rigging off the valve, rather than off the balloon neck) this week. I'm hoping we'll get a chance to at least do another drop test while I'm here (I leave on the 18th, and intend to come back mid-July), and hopefully Konstantin Baibakov from USherbrooke will be able to come down to Hanover for that (if and when it happens). It is currently rainy here, and the weather forecast is sunny this Thursday, and cloudy (but not rainy) this coming Sunday, but is otherwise rainy.
At UVic, Karun, students Marlene Machemy, Caio Simoes de Almeida, Patrick McManus, and I did another 10 km Mt. Tolmie to Observatory Hill test this past Monday evening of the 532 nm laser (before I left to fly to Hanover on Tuesday morning). Marlene and Karun felt the data that we took from the optical test was good, and Marlene is currently analyzing the data to determine the frequency spectrum of the intensity fluctuations due to the atmosphere over that 10 km path. She'll post some results from that when ready.
You've seen the excellent LED additional source design renderings from Houman, and he and Cordell are currently working on the comments regarding fixing possible unwanted optical reflections from that. Houman has also essentially finished writing up the work up in his master's thesis, and will ask us additional questions if any come up.
Susana reported that the JHU group of senior undergraduates is now graduating, following their very successful work on a powered payload, and we'll be looking forward to their final writeup (which should be out soon), which will be an excellent guide for our future work in that area. Finding new students will be a challenge for Susana and Nathan, as next year's senior engineering undergrads will want to work on something new, but they will work on that. And in the meantime we will have their writeup to help guide us.
That's all I remember, please send things that I forgot. Next telecon in 2 weeks, on Thursday, May 21 at 1:30 pm Eastern time.
cheers, thanks all! justin
On Thu, 07 May 2015 01:35:24 GMT, Justin Albert wrote:
> Hi! > > Telecon tomorrow (May 7) at our usual time: 1:30 pm Eastern (10:30 am > Pacific, 19.30 European). Discussion items include: flight plans, light > sources and light source modelling, goniometric and pre- and post-flight > calibration, communications tests, new nanosat bus and payload solid > models, JHU progress, computing/website, grant applications, and recap > of schedules. A reminder of the CSA project timeline is attached. > > Here's how to connect: > 1) Open Skype on your computer (note that of course, you should first install Skype, http://www.skype.com , on your machine if you haven't already). > 2) In the "Contacts" menu, add me ( jalbertuvic ) as a contact, if you haven't already. > 3) Just wait for me to Skype-call you at the usual time (1:30 pm Eastern, 10:30 am Pacific). > 4) If there is any trouble, or if you don't get a call for some reason and would like to join, just send me an e-mail (jalbert@uvic.ca). > > Here's the tentative agenda: > I) Flight plans! > II) New diffused light source and its modelling, pre- and post-flight calibration, and goniometric calibrations > III) Communications tests (possible backup optical and radio, etc) > IV) New nanosat solid models from Houman and Cordell > V) Progress at JHU / STScI > VI) Computing/website > VII) Grant applications > VIII) AOB > > Talk to you all tomorrow, thanks! > justin > > Attachments: > http://projectaltair.org/HyperNews/get/AUX/2012/11/12/18.02-43361-Schedule-20120702_hqp.pdf >
