So far we use Canon A470 model cameras because they are cheap, and the sensor quality is great.

The camera is capable of doing so much more than what is available through the stock options, so we use CHDK to make other features available to us.

To answer your question, I read that the lcd power and the sensor power are connected, so if you turn one off, then you turn both off, and I need the sensor. However, there was an option that I found that allows you to turn the backlight off a millisecond after it pops on, that saves power, but we don’t use it.

We just turn the sounds and the flash off.

If you have any more questions, let me know.

Balloon – 350 grams
Total payload weight – 1.8 lbs
Nozzle lift – 2.79 lbs
Free lift – .99 lbs
Peak altitude – 90,000 feet
Ascent speed – 780 ft/min
Time to burst – 1.9 hours
Helium required – 54 cubic feet
Balloon diameter at launch – 4.7 feet

This data came from a program called Liftwin.

The data above assumes that you are at 0 feet above sea level, and the air temp is 60 degrees. Now this is not rocket science, so exact measurements are not necessary. If it’s 70 degrees outside, your ascent speed changes to 770 feet/min. Generally speaking, it’s better to launch in cold weather as you get more bang for your buck. However, launching in warm weather is absolutely acceptable. The catch is that warmer weather requires you to use more helium to get the desired free lift to get your desired ascent speed. However, more helium in your balloon = lower possible max altitude.

I hope this helps. I would love to help even more if possible. Send me an email at justin@justinhamel.com as I would enjoy speaking to you on the phone about your project.

I highly suggest using a Spot personal tracker. Last i checked, they are about a hundred bucks. Cell phones scare me for this kind of project…

As far as free lift goes, if you have a flight package (ie balloon, parachute, payload) that weighs 1 lb, you are going to have to have more than one pound of lift to make it rise. So if you have 1.5 lbs of lift, then you have .5 lbs of free lift. So, yes. Your jug theory is correct.

I will get the calculations to you soon.

Do you have your project documented? I would love to read about what you did. We can all learn something from each other.

We have talked about getting involved with our local school districts to share our experience and strengthen classroom learning.

I imagine that doing this on your own doesn’t really create many opportunities for useful data collection. I think that with the input of a few classrooms, we could come up with some cool science experiments to send up.

I’m sure that opportunities will present themselves.

I’m glad I could help with the calculations. Let me know if I can be of any more assistance in that area.

My project partner, Chris, and I built a new filler nozzle last night. It took a new hours to make, but it’s solid. I will take pictures of it for you on Wednesday. It’s not too hard to make, it’s mostly time on the lathe.

The new nozzle thing weighs 2 oz. The original one weighed 4.3 oz.

I look forward to learning more about your project. What are your goals?

-Justin Hamel

Thanks for the Calcs!! We were thnking at 65 cu ft…but we’ll go with your 51 Cu ft suggestion. We already purchased a parachute from Kaymont. We have not recieved it yet…but may consider purcahsing the one you suggested. I wanted to see the chute we purchased first and do a few test runs on it befor we abandon it for a better one like the one you are suggesting. Thanks again for the info!! We’ll keep you updated on our progress and look forward to your Nov 11th launch.

So I did a little math for 350 gram balloons.

I assume that your camera, cellphone, payload container, and parachute weighs 1.6 pounds.

If you fill your balloon with 51 cu. ft. of helium, that should result it your payload reaching an altitude of 92k feet.

51 cu. ft. of helium would provide you with .98 lbs of free lift. That will give you an ascension rate of 700 ft/min give or take.

I highly suggest using the parachute that we used. It is incredibly sturdy, but also light weight. I suggest purchasing the 5 ft parachute. The 6 ft is not that much more expensive, but I think that it will not work properly without the proper amount of load. Additionally, it might slow your descent too much.

Let me know if this helps…

-Justin Hamel