Solar Powered Thermal Airship Project

Sir: Congratulations. The idea of a giant fresnel  lens inside a transparent blimp envelope is truly ingenious. Please keep us apprised of your progress on this fascinating project.

 I  wish  you   the  best of luck !  Thanks  for  posting   here !
  Because of  the  super heating   as you  say ,   Normal   envelope  materail ,  as  we  think of it,  will  need to  be  different .  The average working  temps  will  be  hotter  than   a  hot  air  balloon  ? And  pressurized  If  I  read  your post correctly  .   What  options  are you considering  for  the envelope ?      

THis lens is huge, I have never seen one this large.   It would kill a person who fell infront of it, would it not?   Still a fascinating idea to have a lens this big and you seem to have put a clever design out to deal with tracking.  There is something like 1300 watts of energy in a square meter of sunlight, maybe more so that is almost two horsepower potential.   Photovoltaics will acheive 30 to 40 percent of that for less than one hp per square meter of sunlight.  Can you estimate how many horsepower or wattage this thing could produce?
.     Your lens will surely sag under it's own weight, have you address this problem and how it will effect the focus?
I would like to see a scaled down model of this.  Good luck, Metin.

You would need a different lens design, you won't be able to find a one piece lens that large. You could use something like this for a large scale test. http://smallblimps.lefora.com/2010/11/18/new-lightweight-solar-concentrator/

One note, your center of gravity is going to settle under your center of buoyancy. Looks like you might be a little tail heavy with the current drawings. Moving the cockpit a bit forward would solve that.

A fresnel lens that large could probably be manufactured with little difficulty. Of course, having just one lens made might cost a million bucks. You´d need to order 50,000. Now, as for keeping it flat. The lens itself could be sandwiched between two transparent, inflatable cushions. Or perhaps multiple cushions on both sides of the lens. By adjusting the air pressure (or hydrogen pressure!) within the cushions, you could probably keep the lens flat and hence assure a sharp, steady focal point. 

I'm wondering if you should look a lenticular shape for this project.  I can see the reason for the round shape but if the lenticular can be accomodated the streamlining is much better  (much better aerodynamics than the round ball) and ground handling--- (tying the ship down in adverse weather conditions is way superior).

The lenticular shape still gives great ease of movement on the horizontal plane and still able to have the internal fresnel lens track with the sun. 

See:   http://www.skylifter.com.au/  for a great lenticular company that already has a few scaled ships flying (though not see-thru).

I was thinking  along  the  same  lines  as Boldt on  lenticular   Only   using  2 envelopes  of  smaller dia  joined with a keel  and   with a  clear  inflated shrouded space between them for  aerodynamics . This is   for  the lens  to  be  RIGID  mounted  with  no  chance of it  getting   off  the collector  and  causing   ....well ..... real bad  things  to  happen very  fast . After  all   you cant  just  turn  this  lens  on  and  off    in  an  instant .  
 See if this  quick drawing  makes  sense or  not .  
 I'm  not  downing  this concept  so please  dont see my  observations as downing  this     because     I  do  think  it has REAL  merit  .  With  2  envelopes   it  would  be   super easy  to  trim  for  ascend or  descend mode  .     
 IM

god i love the look of this.

using a fresnel you can easily add a sterling engine to this, the heat can do two things at the same time. (three if you use the engine to generate electricity as well as motion)

It occurred to me that if you used steam, you would be generating your lift gas, which would be contained in the envelope it is lifting, condense back to water, be boiled off into steam while running either a steam engine or a Stirling engine creating forward thrust and electricity as well.   It would be an engineering nightmare, I am sure, as steam is dangerous and can collapse very quickly, but it makes the mind wonder of many wonderful things.

a sterling does not need to be open, and steam is not such a good idea. if things cool down you end up with hundreds of litres of water lying around...ie extra weight.

hot air, hot gases, thats the way to go. the sterling can be sealed and work perfectly well.

any idea how much hp can be generated by a stirling engine?  What is the efficiency?  Pretty good isn't it?  Since one can run off of the heat of your hand.   But are they powerful?

Stirling engines are pretty efficient, but the are also fairly heavy. It is hard to find stirling engines in a useful size too. 

They don't have to be heavy. Since they work on the differential between two pressures/temperatures instead of absolute pressures like an internal combustion engine, they can be built from light, non-traditional materials.  You might even be able to use a clever arrangement of the lift bag  or other membrane within the envelop to create an effective sterling engine.  It won't be putting out a lot of power, but it might be enough for this application.  Someone here proposed doing so, but I couldn't find it with a quick search...

Yah, I proposed using the envelope itself as part of a stirling engine. http://smallblimps.lefora.com/2010/11/11/airship-as-a-stirling-engine/#post5

This was to help solve the problem of low power to weight ratios in stirling engines. Heat engine design and thermodynamics are not my strong suits, so this idea never got very far. I think it is a good idea though.

I thought of using the stirling engine to recover heat energy from a gas engine, and then for the heat radiance of an electric motor but it is too heavy and would put out too little power.   But there must be a way to create energy from the heat of a thermal ship as well as get lift.   All things considered, energy is wasted all around us and we hardly realize it.   The great thing about the sterling engine is that you do not have to have an exhaust, you can keep your hot air in the gas bag or envelope.   We could design one and scale it up, but could we get a couple of hp out of it?  If not it would be better to use solar electric power and retain the heat as extra lift.

here are some pages, with good notes on sterlings. in order of importance, from my point of view.

one thing, they can be made to be very light...and for Nav...they are very quiet...

http://www.sesusa.org/

a good video and link to green power science

http://www.greenpowerscience.com/

Metin,

Nice portfolio, like the clustered/modular space habitats.  Also like the layout of your CV. Noticed you are on LinkedIn.  Would like to add you to my LinkedIn account for some (far) future design work...

Yes!!  You can have both a solar powered airship AND a deathray to zap your enemies from above!  LOL.

LOL. That is my other forum, SmallDeathRays,org.