Here are minutes of our meeting on Thursday -- please just reply with (or let me know) any corrections -- thanks!:
Phoning in: Arnold Gaertner (NRC), Yorke Brown (Dartmouth), Cordell Grant and Houman Hakima (UTIAS-SFL), Karun Thanjavur (UVic), and our 3 JHU students working with Nathan & Susana
Yorke and Cynthia did a set of largely successful, however not yet uniformly perfect, drop tests of the dummy payload with the new parafoil and modular cutdown system from the roof of the Wilder Bldg. on the Dartmouth campus last week. They have now made a small adjustment to the new cutdown system and will do a second set of roof drop tests (which will be be followed by a set of tethered-balloon drop tests when uniformly perfect) ASAP. The drop tests of course must be consistently perfect (the gondola wouldn't be much use if dropped from 2+ km and the parachute doesn't open properly), but when they are, and if the weather is still decent in NH this autumn, flights will resume. Yorke additionally has a few needed software updates to make prior to the next flight (and also he'll shortly work on the back-up telemetry card with a second DNT transceiver, but we'll work with the current system in the meantime).
Karun is making progress on Zemax-based computational modelling -- he has contacted LabSphere and AlliedScientificPro for any info they have on numerical optical models for the integrating spheres (or for any of their integrating sphere products), and has begun to create simple standard Zemax models of lenses, laser light etc. Paul and Karun have finished making a very large (about 3 m^3) dark-box in the downstairs lab at UVic, and the computer automation for the spherical-coordinate goniophotometry stand that they have developed is working. In addition to his Zemax work, Karun will also be using the UVic machine shop to make some enhancements/modifications of the portable payload attitude calibration test stand.
Houman and Cordell are progressing well with the 3-D modelling of the nanosat payload, and of the multicolour laser module, and will be contacting us with questions when they arise. They'll also have some new drawings for us to look at soon.
We now have very clear and successful radio transmission and reception at > 1 km (however gets quite flaky at > 3 km with this simple system) using the new 433 MHz radios we have for testing (http://embeddedwirelesssolutions.com/ews_rfm23bp_433mhz_development_kit). Undergraduate Diane Lehmann and I have now tried transmission between the tops of the Bob Wright and the Elliott Bldgs. on the UVic campus (200 meters, completely clear and fault-free), from the top of the Elliott Bldg. to the top of nearby Mt. Tolmie (~ 3 km, fairly flaky), and from the top of Elliott to the top of nearby Mt. Douglas (~ 5 km, very flaky). For the system to be useable at the needed ~50 km range, we'd need to try: 1) using reliable datagrams (i.e. repeat send until assurance of delivery is received) rather than the simple unreliable datagram protocol we were using; 2) using frequency-hopping; 3) using larger and better antennas; and then, if still absolutely necessary, 4) boosting TX power using a 10 W or more amp. However, it's not necessarily clear that taking those steps is, right now, the very highest priority for us: this 433 MHz system would be intended for use in Europe/Asia/Australia, and we are not imminently about to fly there; we could indeed potentially use 433 MHz as a backup in our flights in North America, but first we'd like to try 1) using a second 910 MHz system as backup, and then 2) perhaps using an optical transmission/reception system as the additional tertiary (and potentially extremely long-range-capable) backup, before going to our HAM-licence-requiring frequency like the 433 MHz (30 cm) band here in North America. So, next on this front, we'll be trying some experiments and calculations with optical communication between ground and gondola, prior to proceeding with the further advances to the 433 MHz system.
We now have a simple toy Monte Carlo program to study photon scattering in a diffusive medium (a few plots at https://particle.phys.uvic.ca/~jalbert/photontoymc.pdf) and I'll be posting more on this, as well as on analytic photon scattering calculation results, and comparison between the two methods, very shortly. I've also of course continued my weekly contacts of Dale George and Barry Prentice of Buoyant Aircraft Systems for the superpressure balloon quotation -- this will be the very first stratospheric superpressure balloon made in Canada, so they've had to shake down some issues (mainly to do with making good seals between the gores of the thin polyethylene balloon envelope) before sending us the quote -- and I will contact them again on Tuesday. Additionally I'm working on a proposal for an Ericsson-Canada grant program due by the end of this month (http://www.uvic.ca/hsd/current/facultystaff/rcpd/centres/Ericcson%202014%20Invitation%20Letter.doc).
Our three JHU senior undergraduate engineering design students working with Nathan and Susana joined and asked some excellent questions regarding the cutdown system (hot wire vs. release motor). Yorke and I explained the motivations for Yorke & Max's change from the former to the latter (due to observed limitations on the supplied current) a year and a half ago -- Yorke's website (http://altair1.dartmouth.edu/design.htm) lists the components for the most recent system. Recommendations for JHU include using either a motor-based cutdown system, or perhaps even no cutdown system at all, and just using balloon burst: Cutdown is only really necessary when one is very limited in what site one wants to land in (e.g. on an island -- such as future flights in Hawaii). Design is very much simpler if one has no cutdown system at all. So it might perhaps be a lot easier to just test return-to-base capability from balloon burst, and not add the complexity of a cutdown system for Maryland tests. The JHU/STScI team will of course decide which of these paths they will take.
Skype worked fairly reasonably for this telecon, following some initial hurdles: I had thought it would be trivial to merge calls on Skype after multiple people connect to me; it turns out that merging incoming calls is only possible on the PC version of Skype, and not on Skype for Mac. Thus, the proper way to do a telecon using Skype is for me to call out to a group. So, for our next telecon, I will send out a group call (which will go to every ALTAIR individual who has ever connected to me via Skype, including occasional but rare attendees e.g. Ray Carlberg and Chris Stubbs), and answering will put you through to the meeting.
That's all I remember, please send things that I forgot. Next telecon in two weeks, on Thursday, Oct. 23 at 1:30 pm Eastern time (trying Skype again).
cheers, thanks all! justin
On Thu, 09 Oct 2014 04:57:09 GMT, Justin Albert wrote:
> Hi, > > Telecon tomorrow (Oct. 9) -- our first time trying Skype! -- at the > usual time: 1:30 pm Eastern (10:30 am Pacific, 19.30 European). > Discussion items include: operations status and progress toward flights, > light source modelling, goniometric and pre- and post-flight > calibration, nanosat and new laser module design, computing/website, > grant applications, and recap of schedules. A reminder of the CSA > project timeline is attached. > > Here's how to connect to the conference tomorrow: > > 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. > > 3) Once I am one of your contacts, just click on my contact icon to call > me. You will then be added to the phone conference. (And by the way, > just doing a regular Skype voice call is fine, there's no need to do a > video call, but either Call or Video Call should work.) > > 4) Just send me an e-mail ( jalbert@uvic.ca ) if you have any trouble > with the above. > > Here's the tentative agenda: > I) Progress toward flights, drop tests, robustness improvements, other operational work > II) Light source studies and modelling, pre- and post-flight calibration, and goniometric calibrations > III) Nanosat, new integrating spheres, and multicolour laser module designs > IV) Computing/website > V) Grant applications > VI) 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 >