[Lab] thought about flight

Wed Mar 18 22:17:46 EDT 2015

I saw some videos and a description of university researchers that were using a helium blimp to do autonomous robotics… I came across this a year ago, but can’t find it at the moment. I think they were from GB. What they indicated worked well is have it slightly heavier than air so it would easily come down, but did not take much energy to keep it up (basically at the motor’s minimum setting). It was fairly steerable with props that could swivel. I think it had one prop on each side and another for trim, or perhaps two on each side… This is also less susceptible to wind than a fully buoyant craft.

Using heat is interesting. Mylar would help keep it contained, and you could seal an electric heat source. Chemical, like a candle, would usually need venting. If you take a battery like this (http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=37353 ), it can keep an 80 W bulb on for an hour (it is actually 96Wh). A smaller heat source is probably more than enough…

-Matt

From: Lab [mailto:lab-bounces at artengine.ca] On Behalf Of Jason Cobill
Sent: 2015.March.18 17:18
To: lab
Subject: Re: [Lab] thought about flight

   It doesn't take much (chemical) energy to heat the air enough to go buoyant, there's an old cub scout trick where you hang a tea light candle under a garbage bag (see also Tailand's festival of lights <https://youtu.be/N9Ko-yvJzHU> ) and it'll float away for hours. (Before landing in a wooded area and lighting the countryside on fire)

   Getting enough heat output from a candle to lift equipment, a camera, fans, rudders, might be challenging. What about a small fuel canister - something like a can of spray lubricant or the tube they use in super-condensed camping stoves? I wonder what kind of energy to weight ratio you could get? Now you've got basically a miniaturized traditional hot air balloon. Think of the places you'll go!

   Generating that kind of heat electrically makes me wonder if the lift you produce could ever exceed the weight of the batteries. Maybe if you "warmed it up" from a plugged-in source, then used the batteries to maintain the heat of the envelope? Even without doing the math, I'm skeptical.

   Before you build this thing - consider that there has to be some kind of law against flying canisters of petrochemicals around, particularly near airports. Or not? I leave this as a legal research exercise for the reader.

   -Jason Cobill

On Wed, Mar 18, 2015 at 12:24 PM, Darcy Whyte <darcy at inventorartist.com> wrote:

I love all the new movement towards quad copters and stuff.

They need quite a bit more energy than fixed wing so I've been thinking about buoyancy. Then there's the helium/hydrogen problem.

Has anybody entertained using hot air? I wonder if the hot air came from electricity it would be better or worse than a quad... Perhaps a closed container...

My intuition says it's worse but it's a thought...

--

Darcy Whyte

Art+ inventorArtist.com <http://inventorartist.com/>  | Aviation rubber-power.com <http://rubber-power.com/> 

Contact: darcy at inventorArtist.com | 613-563-3634 by appointment (no text)

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