1
$\begingroup$

The classical rigid airship uses a heavy envelope which accounts for the large buoyancy balloon. This comes on account of aerodynamics. My first concept was a thin and long "cigar" where the cockpit, passenger compartment and cargo room are located at opposite ends for balance. A "fishbone" skeleton connects the two ends by passing through the envelope. I quickly abandonned this idea. Later, I thought of another design, where the different compartments are built AROUND the envelope instead.

The rigid airship's skeleton is like a spoked doughnut. It looks like a bicycle wheel but with a wider hoop. The doughnut serves as reinforcement of the envelope and is large enough for passengers. It is not necessary for the whole ring to serve as a passenger lounge. However, putting passengers and cargo at opposite ends will give a good balance.

The advantages I see are:

  • Structure serves as lounge and skeleton, therefore reducing material usage and weight.
  • placing engines on different areas directly over the skeleton is easy
  • the body is circular and lense-shaped, allowing the ship to handle side-winds better.
  • the buoyancy balloon is behind the front side and not above it, therefore reducing drag.
  • the connection of the balloon to the ship is a long stitch line around the balloon. Therefore, the weight of the ship hanging to the balloon is well distributed along the stitch line.
  • the top side is not as curved as that of the conventional airships. This means that solar panels will receive more direct sunlight. Solar-powered airships are already used as unmanned surveillance stations.
$\endgroup$
  • 1
    $\begingroup$ For disadvantages, see the same reasons that oceangoing ships are not designed as saucers. Think drag, with corresponding extra weight and increased vulnerability to bad weather. Side-winds didn't break up airships often...but up-shear and down-shear did. Also, remember that airships are essentially a bunch of enormous shaped balloons with a relatively small passenger/crew basket slung underneath. Volume for passengers and crew is easy to come by - the governing factor is always weight. $\endgroup$ – user535733 Oct 5 '17 at 19:49
  • $\begingroup$ Yes, but question is about reducing weight and drag. Side winds would make mooring more difficult, but hopefully the shape will allow building smaller hangars $\endgroup$ – Christmas Snow Oct 5 '17 at 20:21
  • $\begingroup$ The saucer shape will have higher weight and drag than a similar-volume cigar shape. The cigar shape is about as efficient as you will get with balloons traveling in a straight line. Saucers were already looked at $\endgroup$ – user535733 Oct 5 '17 at 20:26
  • 1
    $\begingroup$ "The classical rigid airship uses a heavy envelope which accounts for the large buoyancy balloon." Huh? $\endgroup$ – RonJohn Oct 6 '17 at 3:24
  • $\begingroup$ My first concept was a thin and long "cigar" The Hindenburg was long and thin. $\endgroup$ – RonJohn Oct 6 '17 at 3:25
5
$\begingroup$

I think that you're possibly thinking about this in a slightly odd way. Airships are the shape that they are for two conflicting reasons - maximising buoyancy and minimising drag. The former favours a sphere and the latter a teardrop shape. A saucer is a long way from an optimal envelope mass/internal volume ratio.

Your concept of combining load-bearing members with accommodation could work, but by far the simplest solution for that is to go for a conventional zeppelin design but with a monocoque section (similar to an aircraft fuselage) running parallel to the direction of travel, which can accommodate passengers/cargo and also replace a structural beam.

$\endgroup$
2
$\begingroup$

Rather than worrying about the shape of the craft, what about looking at the materials used in building it?

It could be that your society is technologically advanced to the point where it can use Carbon Nanotubes to build things:

CNT are at least 100 times stronger than steel, but only one-sixth as heavy, so nanotube fibers could strengthen almost any material.

Also, could use Graphene aerogel which could be used as an insulating filling, and perhaps even help lift the craft (thanks to @PipperChip)

The classic cigar-shape of flying craft and submersibles is used simply because it is the most aerodynamic shape when it comes to moving through fluid. (Most physics models treat air as a fluid when studying this.) So changing the shape of the craft is likely to create more problems than it solves.

You've already noted in your question that you've had to "balance" the craft.

So I strongly suggest looking at the materials of construction instead.

$\endgroup$
  • $\begingroup$ The physics stack exchange has your back on making aerogels buoyant: physics.stackexchange.com/questions/71069/… . In short, you need to only wrap it in something that keeps the air out. The aerogel could be used to reduce the weight of the craft, creating supporting members, paneling, etc. $\endgroup$ – PipperChip Oct 5 '17 at 22:57
2
$\begingroup$

The only really valid reason to vary from the traditional "cigar" shape of an airship is to utilize the envelope for dynamic lift.

There is actually a class of vehicles which use aerodynamic lift from the envelope to improve performance. The first one I ever heard of was created by the AEREON corporation and the story told in a wonderful book called "The Deltoid Pumpkin Seed" by John McPhee.

enter image description here

AEREON 26

By making the airship neutrally buoyant, the vehicle was calculated to require far less engine power for take off and flight. The vehicle would have many of the attributes of an airship, but be much faster, and have fewer issues in terms of ground handling.

enter image description here

Airships with positive buoyancy have issues when on the ground

A "donut" shaped airship will have very few of the attributes of a neutrally buoyant airship (even if the cross section is airfoil shaped, you have a large and relatively inefficient low aspect ratio wing, rather than a lifting body or an efficient high aspect ratio wing. This is in addition to the already mentioned issues of extra weight and reduced lifting capacity for its size.

$\endgroup$
  • $\begingroup$ That makes me think if a saucer-shaped body allows a hydrofoil effect. The fuselage may incorporate more carbon fiber parts for better strength and less weight. All of that may reduce the required size of the balloon even further. This basically becomes a hybrid airship. $\endgroup$ – Christmas Snow Oct 6 '17 at 5:58
  • $\begingroup$ Indeed neutral buoyancy is essentially how a submarine works. If you're making a lifting body though it's likely that it's actually going to be slightly negatively buoyant. $\endgroup$ – Matt Bowyer Oct 6 '17 at 14:28
1
$\begingroup$

Your flying saucer airship is going to be impossible to control

Every designer for ships that move through a liquid (water or air) has to make some decisions about directional stability and maneuverability. On the manuevability end of the spectrum, a ship with a 1:1 aspect ratio between length and width will be exceptionally maneuverable since there's not much that resists turning. On the other end of the spectrum, a long ship will stay pointed in the same direction with almost no effort.

Your flying saucer is on the maneuverability end of the spectrum so it will be able to rotate to a different direction easily. This is great until you actually want to get somewhere. Your crew is going to have to stay alert at all times to make sure the craft stays on course. For a long cigar shaped craft, going somewhere is as easy as pointing the ship that way. After that the ship will tend to stay pointed that direction.

$\endgroup$
  • $\begingroup$ This may be true for a completely smooth saucer-shape, but a tail (like that of an airplane) may solve the problem. A close scenario is that of hovercrafts. The SR.N1 model is almost circilar in shape and holds two tail fins at the back. $\endgroup$ – Christmas Snow Oct 8 '17 at 18:34

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.