You can get a good estimate of the purity of a gas by calculating the lift per unit volume. The typical "balloon helium" we get here in the UK is about 95-97% pure (the remaining 3 - 5% assumed to be

The latter (rapid ascent and gas release at the desired altitude) . Another idea in the paper is a lift balloon - where the superpressure balloon is filled to just the correct amount on the ground and

Looks like that link does not work - search for the paper "Characteristics and Performance of Three Low-Cost Superpressure Balloon (Tetroon) Systems " Steve

See the ping-pong valve described here: https://tinyurl.com/y5ukveyb see fig 4 Steve Virus-free. www.avg.com

Actually that does look more like the problem. Steve Virus-free. www.avg.com

Hi Zack - Ive not tried (or even seen) that particular pi camera before but I see its based on the 5Mp OmniVision OV5647 sensor - that was the sensor used by the original pi v1 camera. Raspberry pi re

Hi folks - I'm looking for a home-brew unwinder (AKA dereeler) design - I've got a launch to do with a limited launch area and I really need to use an unwinder. Ive seen the designs for the Vaisala an

Cross posted from [picoballoon] - given recent UFO interest: https://www.india.com/viral/ufo-or-weather-balloon-mysterious-balloon-like-white-object-spotted-in-japans-sky-twitter-is-bewildered-4062181

humm - read "in" as inches missed the almost invisible ' Steve

Its possible but quite unlikely I think - 30in balloons (I assume you are talking about the variety used for floater flights with payloads of a few grams) usually float about 8,000m (25,000ft) - about

What makes you say that? From the Hydrogen cylinders used (and rolling countryside) I'd say it was shot in the UK by UK company Sent-Into-Space https://www.youtube.com/watch?v=RoIPcV8FwsQ&t=28s Steve

Wow 797miles (1283Km) is pretty impressive. I assume the great circle distance being referred to is the direct ground distance between the ground stations - rather than adding up the two halves. Do da

My guess would be that the pressure drops as the balloon is released because the envelope is under less tension - held to the ground the full lift of the balloon is transferred into envelope tension -

Here is one I think: https://drive.google.com/file/d/1kPggddrY6XEHVHylGjTU2moUN4Bt7bwz/view?usp=sharing Steve G8KHW/AJ4XE

Thanks Mark - I've just cross posted to the UKHAS group. Steve G8KHW/AJ4XE

The MS5611 is a better chip to use for HAB - its rated down to 10mbar (approximately 28km). Both the BMP180 and BMP280 have an erratic output value issue outside of their rated range. Steve G8KHW

If your using a Raspberry Pi why not consider the Raspberry Pi Pi-In-The-Sky APRS variant: https://store.uputronics.com/index.php?route=product/product&path=62&product_id=52 Steve G8KHW

Cross posting to [UKHAS] Steve G8KHW Virus-free. www.avg.com

Ive been researching Operation Outward - a UK WW2 operation that launched 100,000 Hydrogen met balloons over a 2.5 year period (trailing wires and dropping incendiary devices on Germany). There were m

Word from the other side of the pond:- The Mancunian Balloonian project at the University of Manchester UK ( http://manseds.co.uk/index.html ) have been using the API to the Habitat predictor to do Mo