Common Production Shell

I want to pitch a new idea. I want to build a basic airship shell that can be mass produced. Then people can add whatever systems to it that they want to. It will be modular. The basic shell will be comprised of a super cheap envelope (like the shroud Nav plans to use) and a basic ppg style gondola with a motor mount plate. 

I think the beauty of the approach is that people can modify the basic shell to do whatever they want to. They can mount whatever engine they want to. They can add structural supports and mount  multiple engines if they want to. People can operate at full buoyancy, or they can super heat with exhaust. You can upgrade the gondola to an optional trike (like IM is building). You can make the shell into whatever you want and you don't have to build everything from scratch. You only have to build the modifications. This allows for the reduction in cost that comes with larger production numbers. We can use 4 stroke engines, 2 stroke engines, solar power, generators, or whatever. All you would have to do is bolt it on and meet the UL requirements. You can super heat your gas too because it does not raise the maximum lift (and thereby the maximum weight) very much. It is mostly for variability.   

There must be a couple of basic concessions. We have to use a common shape for the basic envelope. This shape can be modified, but the basic shape should be versatile enough for many people to be happy with it, while being cheap. So for this shape I propose a lenticular envelope with only 2 gores. One top circle and one bottom circle. We could use the uber wide sheets of shrink wrap that Nav has sourced. It will inflate into a good versatile shape that is good for up, good for sideways, and pretty good for forward (better than a sphere).  

Two, we may have to accept a leaky envelope that may not last for very long. I think this will be more than offset by low cost and mass production. If we make 10 or so envelopes, we can make them for hundreds rather than thousands of dollars a piece. If we want to use a less leaky envelope we can, but we may not be able to find it is super wide rolls. 

This is just an idea, what do yall think?

Certainly interesting. I'm imagining a sectional ring having two bands sandwiching the gores. It's not hard to bend aluminum or plastic into a large circle. This would construct the ship similar to how embroidery hoops are done, but flat instead of on edge. An opening above the pilot would allow for inserting cells and adding heat if chosen.

The  Shell  is not  the gas  envelope   in  this  idea ?  Its  a shrouded  frame  to  hold  what  ever  gas containment system   you  choose ? 
 Rolling  tubes into  hoops  Is   a non complicated and  least  expensive  process .  You  could  even  build a Tubing  roller at home  and hand  crank it    for  not  much.  Get  a  wood  shop  to  make you some  round   hard wood  dies  that look like pulleys  to  fit  the tubing  you  plan to use.  The  circumference   of  the  shape  will be  rather big   so  the  deflection in  each  tube  section  wont be extreme. 
  This is  where modeling pays off  big  time . Are you  planning  a  RC version Dude?

I was calling the basic setup the shell. That would include an envelope/shroud and a harness with a mounting point for an engine. It would be the most basic airship possible, but without an engine already mounted. 

I haven't yet planned any modeling. Most of the complicated work would be done by people who customize the basic shell. So modeling the shell would be easy and straightforward. 

The top half of a  T 10 round parachute (  surplus  store )   would produce the gore type patron for lenticular  ,  I  would say   "maybe  " some form of non stretch   top panel reinforcement  maybe  required  here , or maybe   Just  the  webbing  with out the gores  in  the  chute ,  to  take  the  stress of the upward push of the gas in  the  envelope  and  transfer it to the load ring . .

Surplus parachutes should make good slow speed airships. For a lenticular just oozing around the neighborhood, with the cool swiveling gondola setup. The two chutes join at the center with a nice rigid ring to suspend stuff from. There are sun-shades or something I saw that reduce to a much smaller shape by twisting the perimeter ring in over itself. A cute trick to put the ship away.
Work out a way to deal with the lift cells and you have a winner.

The "common shell specification" encourages an organized airship project. A standardized  body serves to channel creative thought toward one objective.

   It's a good topic for the Webcon Tuesday evening. I think lenticular is a beautiful aeroshape and offers lifting body dynamics and is the best way to go but with form-modifications to solve aerodynamic difficulties.

We can all input our preferred ways to make the lens fly.

I still haven't replaced my faulty microphone, but I'll try. Getting a lenticular to fly right should not be impossible. You put a good tail and stabilizer on it, and there you are.

The  RC hover disk   does  a  real nice job  of  flying  slow  and stable .
  Fins  and  elevator  on  the bottom for  a  airship  ?   Fins  have  wheels   on bottom   and  a nose gear on  the   Gondola ? 

Yep, the RC Hoverdisk looks pretty stable. Just a matter of economically scaling it UP!, I'd say.

Indeed. And that is a very aggressive shape, making aerodynamic lift. Think how much easier it will be with the addition of pendulum stability and while at a lower angle of attack. 

Also we talked a little about the envelope for a common production shell. Nav says he has identified rolls of shrink wrap that are up to 40 ft wide. If we use that material, we can build the envelope with only 2 gores: one top circle attached to one bottom circle, just like grocery store balloons. This would be super cheap and easy. We just need to get a better estimate of how much volume a 40 ft diameter (un-inflated) balloon will have. It needs to be enough volume to lift about 400-500 lbs. For reference, I calculate that a sphere 24 ft in diameter (inflated) provides enough volume to lift 500 lbs using hydrogen. So I don't think we will have any problem getting that much volume from a lenticular shape up to 40 ft in diameter. I figure we could experiment with a grocery store balloon to get a better estimate of volume compared to a sphere of the same diameter. 

A 40 foot diameter saucer shape four feet high at the edge and cones 30 feet in diameter at six feet tall each is 16 feet thick in the middle and has a volume of about 7993 cubic feet and lift of 519 lbs with helium at 0.065 lbs per cubic foot

 With 2  sheet construction   It  would be   constructed just like  the hover disk , With a  outer rim  pocket  for  the circumference tubing  hoop  .  Being  out side the  gas lift  chamber ,  the hoop  can   easily  be  accessed  for  adding  attachments  on it ,  and  also  the tubing  sections themselves  joined together  easy  by  having  openings  in  the  rim pocket .   It  would be  Way Cool! 
   Now  being  a relatively unknown  in its  gas  retention qualities   , this  40  ft  wide shrink  wrap   boat cover stuff. in a flat  sheet configuration  Could it  now  , be  a super   easy  process to  add  the aluminized  nylon  to  the  inside side  of  the  shell?  or  even use  aluminum  foil  itself  using  a  spray on  contact  adhesive .  
  What I'm getting at  here  is   Not  so much  a  Gas  tight  envelope out  of some type of  foil. Although  we  would  strive to  make it  as tight as  we could , the  heat  shrink   is  the gas tight part ,   The foil is more of  a  gas reflector  now,  making it  harder  for the gas to  find its way out and  extending its  UP  time  a grate deal .  Just  a thought .
 This site  says  40 ' X 100'   7 mill weighs  141 lbs.   So  2  -  40'  circles would  be  about  100 lbs  I'm guessing .  276. 06   dollars  not  bad  .  http://www.bigshrink.com/shopexd.asp?id=996
 

Yah, the shrink wrap could be augmented with liners to improve gas retention (I like the idea of gluing on foil). Or you can use internal gas bags. You can do whatever you want to improve the basic design. That is why I like this concept so much. 

The shrink wrap weighs a little over 1/2 ounce per square foot, that is pretty light, but, sadly has no cloth reinforcement to keep it from billowing out terribly between trusses.   Also you cannot glue anything to it until you are done shrinking it with heat. and it will be difficult to glue anything to it from the inside once it is assembled and impractical to do it from the outside.   I think, however, it may be possible to PAINT it with a layer of acrylic.   I believe your best bet then is to use heavier inner gas bags.   I think your real problem will be the weight of the skeletal frame.  Aluminum will be too heavy and expensive, 2 inch PVC is a little flimsy but can be pressurized to over 100 psi.   You will need landing gear to keep it level on the ground.  Consider the design of the Reliant from "The Wrath Of Khan" it has the saucer shape, landing nacelles with good steering and plenty of lift and it's a good lifting body shape.

  It would be disastrous to the reputation of personal airships for someone to accidentally drown in an unintended water landing. The convenience of water landing can't be ignored. A moored airship could clock around on the water, like the early floating hangars. We have members in Alaska, where float planes are the popular way of travel.
  Maybe water landing is not what a common production shell would do, but it would be a good alternative. The simplicity of the swiveling motor cloud hopper will appeal to most, but there will be a market for the saucer with landing pods. It's more complicated, but it has more versatility of use.

Indeed Mike. You can always add that capability later since floats don't even add to your UL weight. 

Right ,  I dont think  shrinking  the   material  in  this particular  instance   was  the  idea.   It  its  size  and price  in a single  sheet   that  has  the   interest  .   Therefore   "skinning  the inside"  could be  practical. 
  I  was impressed  with the  bursting  strength  !  235 PSI   is   mighty  impressive  !  It  may  not  need  any  reinforcements  such  as   parachute   webbing  as mentioned   earlier .  I dont think  solar  heating  will  be  enough  to  shrink  the material   in  flight , unless  it  was painted  flat black.   
  Here is   some food  for  thought.   Just Suppose    the  shrinking  capability   could be  used  in  selected  areas  for  shaping   to  a  desired  form or  adding  aerodynamic  detail s ...???      

You certainly could shrink certain areas to reduce bunching, like around the equator. I would probably be scared to that though. I wouldn't want to risk ruining the bag after it is built. 

 I dont think  it  would  be  an  issue ,  With the  scrap  pieces,   you  could  get  very handy  with  learning  how  it  reacts .     Even  a  hot air gun  could be used   instead of the propane  blow torch. If you  were  still  squeamish . I've  seen this  wrap used at Ranger Boats  .  Its  hard to   NOT  do it  right . 8)