Half a croissant, on a plate, with a sign in front of it saying '50c'
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Quis custodiet the custard?

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Solar Blimp

just a little faster than a balloon...
  (+11, -2)(+11, -2)
(+11, -2)
  [vote for,

Build a blimp with a huge black air chamber on top. The chamber should cover the entire upper area of the envelope and have valves at the front (spring loaded, so air can get in but not out) and at the rear (also spring loaded, so it opens when chamber pressure rises above a certain level and closes when the chamber is empty. As soon as the blimp is in motion, air enters the chamber through the front valve until the chamber is full. The trapped air heats up in the sun until the rear valve opens, propelling the blimp forward slowly. When the chamber is empty again, the whole process is repeated. (Several chambers could be used to give a smoother ride)
RaoulDuke, Aug 17 2005

Moebius heated airship https://www.thepari...io-a-moebius-14.png
[unhelpful_fool, Jun 04 2019]


       The blimp is in motion when the rear valve opens, but that very motion causes the front valve to open, hence both valves are open at the same time?
If the valves were motorised, then it would work better, I think. Gulp, heat, fart.
Ling, Aug 17 2005

       I´m not sure if both valves need to be motorised. The front valve won´t open during the power stroke, because the chamber pressure is above atmospheric pressure.
RaoulDuke, Aug 17 2005

( + )
.\ /

       Not exactly a stirling engine, because the air is not cooled inside the engine. More like a solar heated pulse jet engine. I think the intake should be at the bottom of the blimp, so rising hot air will make the engine self-starting.
RaoulDuke, Aug 18 2005

       //pulse jet// ... er, more like "peristalsis". Very nice, bun for you. Get there before sundown!
lurch, Aug 18 2005

       Assuming you have a destination in mind, how you gonna steer this thing?   

       Don't care where you're going? Then why worry about making a little extra groundspeed?   

       Pretty interesting, though.
bpilot, Aug 19 2005

       The blimp has a rudder and an elevator. Maybe the exhaust valve should be at the end of the rudder for faster turns. The whole thing could be made from a flexible material like a paraglider.
RaoulDuke, Aug 21 2005

       You'll not get anywhere fast, but for the idea of pootling around under the power of solar farts, bun.
moomintroll, Aug 21 2005

       Run a spine of concentrating power mirrors to a fluid and you could get a more effective system that looks like this thing from Moebius.
unhelpful_fool, Jun 04 2019

       // //pulse jet// ... er, more like "peristalsis". //   

       No, I'd say it's a solar pulsejet that happens to have a peristaltic motion. It could be actually peristaltic if the chamber wall had muscle wire or something in it that contracted under solar heating. But then you'd need a way to synchronize or sequence the muscles to pulse or peristalse*.   

       *Neither "peristalse" nor "peristalt" is in any dictionary I've checked (verbs for that noun and several similar ones being lexical gaps in English), but the Google cloud spellchecker accepted the former as a plausible word after less thinking time.   

       // this thing from Moebius //   

       What… is that thing? (Other than "very imaginative", of course.)
notexactly, Jun 11 2019


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