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 Post subject: Cautions and Concerns on re-entry??
PostPosted: Tue Nov 29, 2011 11:29 am 

Joined: Tue Nov 29, 2011 9:08 am
Posts: 3
Greetings,

I would like to try a Near Space type launch and recovery. I have a question that has been bugging me.
Are you ever concerned about your balloon causing a wreck or property damage when it descends?
I picture a worst case situation like it descending on an interstate and causing a wreck.

Once launched , you can’t guarantee where it lands and that it won’t be near a busy highway – can you?

Next – while less severe than a car wreck, what about the balloon and box causing property damage?
What cautions, safety, and liability type concerns do you consider before a launch?

Thanks
-Sparky_


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 Post subject: Re: Cautions and Concerns on re-entry??
PostPosted: Thu Dec 01, 2011 6:47 am 

Joined: Wed Aug 03, 2011 10:01 am
Posts: 22
All very good points. This is one reason the Citi commerical bothers me a little bit, there's no hint at the safety issues involved.

Prior to a launch, I run flight predictions based on the characteristics of the balloon and parachute. On my last flight, I assumed an ascent rate of 1,200 per minute and a final landing speed of 1,000 feet per minute. The maximum altitude was predicted to be 85,000 feet.

With these numbers, I go to the Near Space Ventures website (nearspaceventures.com) and used their online Balloon Tracking software (Baltrak). I load these numbers into the webpage and selected the closest airport to the launch site. Winds aloft data (predictions) from a part of the National Weather Service combines with my flight description to predict the flight path and recovery zone of the near spacecraft. If the flight path looks safe, I'll launch. If it doesn't look safe, I'll delay the launch or move it to another location. Because no prediction is 100%, I look at the descent portion of the flight to make sure it doesn't pass over a major town. I also look at the area surrounding the recovery site to make sure it doesn't include any dangerous areas. The azimuth of the recovery zone is usually pretty good, but the range can be off (balloons never behave eactly like you think). So I'm really looking at an ellipse around the recovery site.

I file a NOTAMS before lift off so pilots will be aware that a weather balloon is going up. The National Weather Service launches nearly 200 weahter balloons daily and has done so for decades. As far as I know, no damage has never been caused by these flights. So adding my six or so flights per year is not significant.

Fortunately, when you look down from near space, the earth looks pretty blank with almost no indication that humans live on it. The percentage of surface area covered by human-made structures is tiny compared to the land as a whole. The chances of landing some place I don't want to land is pretty low.

Onwards and Upwards


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 Post subject: Re: Cautions and Concerns on re-entry??
PostPosted: Fri Dec 02, 2011 11:57 am 

Joined: Tue Nov 29, 2011 9:08 am
Posts: 3
Thank you - I'm just starting to read up on this hobby - I did not know about that websits.

Thanks again
Sparky_


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 Post subject: Re: Cautions and Concerns on re-entry??
PostPosted: Fri Dec 09, 2011 6:33 am 

Joined: Wed Aug 03, 2011 10:01 am
Posts: 22
No problem. Be sure to check my website, nearsys.com. I have links under publications to my near space book. It's a free download from Parallax.

Onwards and Upwards


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