HacDC Spaceblimp

A collection of stuff about HacDC's near space initiatives, including the Hackerspaces In Space Contest entry (2010).

Documentation

Spaceblimp-2

Flight date: 8/21/10

Time of liftoff: 10:47 (All times are GMT-5)

Time of touchdown: 11:49

Time of recovery: 12:20

Total flight time: 1:02 (62 minutes)

Liftoff to recovery time: 1:33 (93 minutes)

Touchdown to recovery time: 0:31 (31 minutes)

Weight of payload/chute: 1lb 13oz

Total cost of launch:

Airframe & Rigging:

Balloon: 800g Kaymont/Totex latex weather balloon cost: $?

Parachute Cord: 250-lb test Dacron line

Balloon Cord: 50-lb test Dacron line

Fill: 180 cubic-feet Helium - cost: $90

Chute: Rocketchutes flat 24" - cost: $9

Capsule: Insulated lunch pail (free, valued at ~$7)

Payload:

Canon model PowerShot SD300 running CHDK (Canon Hack Development Kit) intervalometer script - cost: $20

Canon Li battery cost: $3.25

Canon 2GB SD card: $6

Falcom (uBlox based) GPS receiver + Serantel Antenna module - cost $47

Radiometrix VHF Narrow Band 300mW transmitter - cost $38

Ultralife U9VL-X Lithium-Manganese Dioxide non-rechargable battery cost: $7

Flight computer/Terminal Node Controller (TNC) - cost $19

HacDC Spaceblimp Flickr Group Pool

/ aprs.fi Flight Map

Some details on the avionics:

Our balloon carried a minimalist avionics package consisting of a custom built APRS tracker and a Canon PowerShot SD300 digital camera.

The camera is configured to take pictures every 20 seconds using CHDK (http://chdk.wikia.com/wiki/CHDK) and one of the stock intervalometer scripts. It is powered by its own rechargeable lithium battery and operates independently of the tracker.

The tracker is based around an atmega328p AVR microcontroller, running code derived from an open source AVR based APRS tracker called the WhereAVR (http://garydion.com/projects/whereavr/). By updating the sine wave generation code to use filtered 7-bit pulse width modulation in place of the 4-bit resistor network, we were able to improve tone quality with a reduced part count. A few additional components were added, including an I2C eeprom for local backup of flight data, external and internal I2C temperature sensors, and a cutdown MOSFET for switching power to a short strip of nichrome wire coiled around the balloon line (the cutdown system was not used in our final flight because we were apprehensive about the complications it added to the balloon rigging).

To keep things light, compact, and simple, we designed a surface mount circuit board to integrate all of the trackers components with a Falcom FSA03 GPS module and a 300mW Radiometrix HX-1 144.39 MHz transmitter. The board was fabricated using the toner transfer method and hand soldered.

For an antenna we used the common 300 ohm twinlead j-pole design (http://www.qsl.net/wb3gck/jpole.htm), tuned as close as possible for use on our frequency (144.39 MHz) and fed with a short length of 50 ohm coax cable for routing/strain relief.

The tracker is powered by a single lithium 9v battery, and regulated down to 5v and 3.3v by linear regulators on the board. The typically undesirable loss of power to heat with these regulators is useful in this case for warming the electronics in the extreme cold temperatures encountered during the flight.

Each chase vehicle had a radio tuned to 146.415 for simplex communication between the vehicles, and another radio tuned to 144.390 for receiving packets from the balloon. For packet decoding we used radios with built in TNCs or laptops with external modems/soundcard modems and TNC software (Soundmodem and Xastir for Linux, AGWPE and UI-View for Windows).

Press

Email from Heather Goss (8/25/10)

(DCist, http://dcist.com/profile/dcist_heather/posts)

"I'll probably run most of this as a straight interview -- if it helps, answer lengths of a sentence or two, to a paragraph are usually good, unless it requires a more detailed answer. Can't wait to hear more!

• Can you tell me a little about HacDC? How did you get involved? What kinds of other big projects have you done?

The official description of what we are can be found at http://hacdc.org/about/. The shorter version is that HacDC is a member-supported space dedicated to making things by inventing, extending and repurposing new and junked stuff. We also research common interests by forming working groups and building projects, and building associations with like minded communities of interest, in DC and beyond. The general public is welcome to all events and is encouraged to join the hacker space.

I [Alberto] came to HacDC via DorkbotDC the DC chapter of the international group of people to doing strange things with electricity. Two of our members, Nick Farr and Adam Koeppel were DorkbotDC regulars and they germinated the idea to form a hacker space on DC. A joint DorkbotDC and HacDC build-a-thon event was planned at the Koshland Museum of Science, spearheaded by DorkbotDC regular Mark Adams. The first friends and members of HacDC came from that community.

HacDC is a relatively young organization but has organized several workshops aimed at teaching the basic skills necessary to be able to approach present and past technology with the creative mindset to mutate it in an innovative or idiosyncratic way. HacDC maintains a wiki with much of the organization's history (in progress) including ongoing and past projects: http://wiki.hacdc.org/

• Tell me about Hackerspaces in Space. What was the goal? How many groups were involved?

The Hackerspaces in space contest was initiated by Workshop 88 (http://www.workshop88.com/), a hackerspace in Chicago. According to their website, 19 groups are involved from as far away as Thailand. The contest officially ended on August 31st. The rules are here: http://www.workshop88.com/space/assets/download2.php and include rules on cost, launch and recovery team size and scoring criteria include retrieval time, weight of package, and cost. Our working group was dubbed the spaceblimp project (because near-space balloon didn't have the same ring to it and spaceblinp has a 70s disaster movie feel to it) and included a small core group of very talented and motivated people who dedicated many, many hours of planning, design, experimentation, funding, and execution.

• What was your experience building the spaceblimp? Did you have any interesting challenges to overcome? How long did it take to build the blimp?

The rules were pretty limiting and we're still not sure where we rank. We learned that it's difficult to get a balloon into near space cheaply. We lost one balloon the week before the successful launch and that was demoralizing and traumatic. As with most projects, the highly motivated few who drove the process had the most to lose so they were more nervous than the bystanders.

• What was launch day like? (I'm curious more about everyone's feelings/reactions than a blow-by-blow of the day. Also can you give me the nitty gitty -- time, location, how long did it run.) Did anything surprising or crazy happen?

The final launch took place on August 21, at Camp Spring, MD. The jet stream was acting crazy so the balloon deviated from the original prediction. The team was divided into launch and recovery subgroups. They both became parts of the chase team once the balloon was aloft. The stats on the launch can be found on the wiki: http://wiki.hacdc.org/index.php/HacDC_Spaceblimp#Documentation

"My feeling, at least, was excitement mingled with extreme dread; we'd lost the last capsule pretty badly, and if this one didn't make it we would completely miss the competition deadline. I really wanted to see it all go well, and it's really thrilling to do that countdown and release it into the sky," recalls Tom Cohlmia.

• What were the results of HacDC's launch in particular? Was it successful? How high did it go? And were you able to recover your payload? Did any other blimps achieve something spectacular?

Ours was a big success! The payload went to 60,000 feet, and then parachuted back to the ground. The payload was found in someone's backyard, a few feet from their swimming pool. Everything was intact, though, and the pictures turned out great. Total time from launch to recovery, 1 hr 33 mins, travelling 27 miles as the crow flies.

• What are the applications of the spaceblimp project? (What kinds of research can be done with blimps, and/or can even the process of developing new near-spacecraft like this help us in other ways?)

"If there's anything else you want to add, please let me know! Also, please send along any helpful links (I've got the ones to HacDC, Hackerspace, and the Flickr page), as well as a short bio describing you and anyone else who responds. Thanks!"