Comment by Machinery Max on March 18, 2012 at 11:23pm

beautiful! would buy one. i'm wondering if it can be solar-powered. not elimitating battery of course

Comment by Andrew Rabbitt on March 19, 2012 at 4:55am

Thanks Max!  I doubt you could do solar power successfully without an odd looking aircraft - well, more odd than this one!  The Helios is probably the best example of what actually works.

Also, on the forward swept wing, most of the wing area is behind the CoG, so adding solar cells is putting mass in the most sensitive area.  Getting the CoG forward far enough has been something of a challenge without adding to it.

Actually, as my brother pointed out to me over the weekend, the Helios holds one of the records for sustained straight-and-level flight at 96,863 feet!  Proof that you can still fly when you get up there! :) 

Comment by Andrew Rabbitt on March 19, 2012 at 5:14am

I wanted to add back into the blog two posts that were made when this blog was accidentally published too early.  The first was:

bGatti - You might change the diagonal to avoid landing on two parts. If the "cockpit" piece sloped \ instead of /, this smaller and more easily replaceable piece would likely absorb the balance of bad landings.

and the second was:

MC - Andrew, It is very nice visually appealing design, very good animation and fantastic music selection! Is it legal to use (quad band) GSM on high altitude? I think there are some rules and regulations where  (how high) can we use GSM.  What about the rules/regulation about the size/weight, on-board avionics selection for the HAB operations?  Is it legal (how to make it legal) in Australia to launch HAB with such a payload?

@bGatti, I guess a bad, nose-first landing will take out the nose-cone, but a good (auto?) landing will actually only land on the main fuselage, at least on level ground.  I take your point though and will consider the strength of the nose-cone intersection under a 'sub-optimal' arrival!

@MC, you raise two very interesting and important questions. Firstly, I know that the FCC have a ban on mobile/cellular communications use whilst airborne, but I don't know of anything similar in Australia.  I have done some searching for regulations about this but I wouldn't claim to have any definitive answer in this area.

Regarding the operation of the whole rig in Australian airspace, the regulations that apply are in CASR101 under free balloons and, presumably model aircraft - it will always be an amateur/hobby project, at least as a HAB payload.

The free balloon regulations are pretty easy to navigate and people have already sent HAB's aloft with payloads of similar and larger masses, presumably without getting into trouble.  As far as the model aircraft aspect is concerned, there are a few greyer areas and I read that OCTA, as long as I have line-of-sight, I can (claim) all is OK.  One thing I must check is whether class G, or anything considered OCTA goes beyond FL100 - I should know this, being a (lapsed) PPL, but...  Ultimately, I may choose to fly in an ambiguous geographical area and leave it up to the authorities to prove any flights actually occured in their jurisdiction...

In any case, if and when the flight actually occurs, I will be doing my damnedest to ensure no conflict with manned aircraft.

Comment by Dez Socks on March 23, 2012 at 11:25am

In 1983, AeroVironment obtained funding from an unspecified US government agency to secretly investigate a UAV concept designated "High Altitude Solar" or HALSOL. The HALSOL prototype first flew in June 1983.

1983.....1983 and we still cant use it. I'm looking into amorphous solar cells but i only just want to supplement or run extras on board

Comment by Mike Wrobel on March 26, 2012 at 9:22am

Andrew,

  Have you made considerations for cold-soaked batteries?  I used to test missiles and we had special issues with even mil-spec batteries at -65F (-54C).  You are going much higher.  Did you consider temperature?  How about temperature on your servos?  Motors?  Hinges?  Might be able to put a warmer on the balloon side, but still might need something for the descent to keep things warm.  Good Luck!

Comment by Andrew Rabbitt on March 26, 2012 at 7:47pm

Hi Mike. There is an earlier blog post where the issues of thermal management were discussed. It turns out to be less complicated in practice than first imagined

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