Definitely great to hear from other people doing this! I see you have a launch coming up in September. I think lots of us would love to come see it, if you're open to people attending. We should definitely take the opportunity to learn more from each other. I see from your website that your first launch went about as well as ours did!

@J, I think we already talked among ourselves about doing one of those as a future project, but I did want to pipe up with interest from here (or at least, I certainly still want to do that!)... we should figure out exactly what instrumentation we want on that capsule--maybe spend more than thirty minutes on that one. (:

@Ryan, somebody from Greenville media asked me if we had been communicating with your group--at the time we hadn't, but it sounded like they wanted to talk to you. Did you manage to get a little press from them?

I'm game! How high do you think we could go?

The altitude we can achieve depends on how light we can make our capsule, and how much we raise to fund the launch!

If we could come up with some shared funding model, we could collaborate and together go higher than we could go alone. I’ve heard of other clubs financing it like this:

Each launch gets team members; each team member puts in two amounts. One amount is guaranteed to be used up in flight: helium & balloon, and tiny misc. The second amount is an equipment contingency. So, if we get the capsule back, we all get our second amount refunded. If we don’t get the capsule back, the second half goes to replace hardware.

So, each team member puts in $X (one-time charges) and $Y (equipment contingency; refunded when we get capsule!) The more team members, or the greater we charge ourselves, the higher we go.

If we shot for these altitudes (no guarantees!) I would estimate our out-of-pocket costs for the one-time-use items as follows:

80,000 feet: $125
90,000 feet: $145
100,000 feet: $165
110,000 feet: $185
115,000 feet: $245
120,000 feet: $375
125,000 feet: $525

That is with our the same weight as our Mark II capsule, about 1.9 pounds.

Note that the costs start going up a lot…to get a little more altitude. You have to buy BIG balloons, and the cost goes up dramatically!

These costs are different than our ‘contest costs’ for the last flight. For a non-contest launch, we are paying ‘full price’ for out-of-pocket items. That is, we don’t pay for the SPOT, camera, parachute-- we have those things. But, we do pay for the full tank of helium, plus delivery, haz-mat, shipping, taxes, etc-- stuff that wasn’t included in the contest cost.

So, 100,000 feet….$165….20 team members…..$8.25 each.
So, 120,000 feet….$375….20 team members…..$18.75 each.

Plus, for 20 members, about $10 each in equipment contingency; we each get it back when we recover the capsule!

My estimates, anyway! That is a ‘skinny’ altitude shot: no extra bits of equipment: SPOT & Camera only. We could launch one in September, if we got enough team members that wanted to do it.

Jonathan

I can't find a stitched photo anywhere! Could someone post a URL?

To the team: I was actually waiting to see more photos, then was going to try and stitch some of them for you. I use Realviz Stitcher for panoramic photography. Would be happy to do it, if someone would point me to a photo repository.

I like the proposed Sunday, September 26th!

I propose we set a $X that enough people are comfortable with (e.g. $10, $20) and then we order the largest balloon that our funds support! We'll need a some minimum number of people to make it happen.

The way the smaller cylinders works out, the balloon size doesn't make much of a price difference in helium. That is, if we bought the small bottle, we'd have enough gas for any of the balloons we might buy. (Price per cubic foot is higher than the contest balloon, but out-of-pocket is smaller.)

Altitude recorder: we can put more bits in the box, including a very small/light GPS (e.g. the eTrex Vista, ~150g) to log altitude data. We will achieve a slightly lower altitude, and we'll need a slightly higher $Y amount (lost equipment contingency, refundable.)

We could use APRS also; same issue though. More data, but lower altitude. I have an APRS that has flown a couple times. We'd get the benefit of real-time altitude tracking, and we'd get the data (iGated) even if we don't get the box back. (I propose we TEST this on a long line, to make sure it is getting i-gated, before releasing the cell.) This is 581g, with batteries; also pushes the $X cost a little for more AA lithium, and the $Y up for unrecovered capsule.

Jonathan

Would that be for both one time charges and equipment contingency? My first thought would be to say $25 but there's something powerful, I think about making it $20 since people can just reach for a $20 bill and donate that. So, how about we say $20 and then go recruit as much as we can?

When I was thinking about how to get altitude an eTrex Vista was actually my first thought. I've heard that the GPS receivers do work that high, and even if not it has a barometric altimeter which should hopefully work too. And, it will save it to a tracklog that we can retrieve later. I really do want to fly APRS again in a future mission, but I think if we're trying for altitude that we should make it as simple as possible and I think it doesn't get much simpler than an eTrex Vista.

A world record is definitely out of our pocket book, based on this article in Wikipedia:

http://en.wikipedia.org/wiki/Flight_altitude_record

Unmanned gas balloon

The altitude record for unmanned balloons was (1991 edition of Guinness Book) 51.8 km (170,000 ft). The vehicle was a Winzen-Balloon with a volume of 1.35 million cubic metres, which was launched in October 1972 in Chico, California, USA.[citation needed]

In 2002 Japan achieved a new record: an ultra-thin-film balloon named BU60-1 made of polyethylene film 3.4 µm thick with a volume of 60,000 m³ was launched from Sanriku Balloon Center at 6:35 on May 23, 2002. The balloon kept ascending slowly at a speed of 260 m per minute and successfully reached the altitude of 53.0 km (173,900 ft), establishing a new world record for the first time in 30 years.[11]

I really like the idea of hosting an altitude competition.

The guys at workspace88 have been great, but I was surprised at just how small a group they are - a fairly small hackerspace near Chicago - we easily have more people involved in our nearspace attempt than all of workspace88 (unless I misunderstood their size from their wiki page).

The point is that if they could pull off the Hackerspaces in Space challenge that captivated the attention of so many people and teams - us included - I do strongly agree that we could put together a similar competition for an altitude competition.

Great idea... ;-)

Actually, 10 members at $10 equipment replacement each ($100 total) wouldn’t be enough to replace gear if the capsule was lost.

So, it would have to be $20 + $20. Maybe that is too much?

Jonathan

whew.

we certainly can't have another contest by the 26th. are we doing a height shot first and THEN a contest?

sorry--it's been a busy couple days; I'm still here and watching!

Yeah, that's what I was thinking was meant--just trying to clarify. tx, @R.

Just a thought, but what about having a contest to coincide with the NC State Fair - Oct. 14-24th. TechShop RDU will have a booth there with TONS of exposure.

yep - I just remembered that a factor of two in density doesn't really translate to a factor of 2 in lifting capacity.

Duh!!!!

It's only about an 8 % increase (comparing with density of standard air).

But IS a lot cheaper. How MUCH cheaper??

I'll wager someone can come up with those specifics quite readily.