Sign in to follow this  
Followers 0
Northstar1989

Giant Airships. Awesome!

32 posts in this topic

Posted (edited)

So, there has been a lot of excitement in the past few years about certain companies working on new, modern, ultra-large cargo airships- most notably the Aeroscroft designs, the largest of which may be able to lift 450-500 tons!

http://www.nextbigfuture.com/2016/03/hybrid-airships-nearing-significant.html?m=1

I thought this was awesome, and very Kerbal somehow- especially because with Airships the "Build It Bigger!" principle really does apply- particularly thanks to the Square-Cube Law (which in this case means that for an airship with a given envelope thickness the total mass of the envelope only increases with the square of the dimensions, whereas the enclosed volume increases with the cube of the dimensions)- meaning that larger airships have relatively higher lifting-capacities thanks to needing to devote relatively less mass to the envelope material compared to their size...

Awesomely, Wikipedia even specifically mentions aerostats (balloons, blimps, etc.) as beneficiaries of the Square-Cube Law in its page on the subject.

Also, check out this Popular Mechanics article on the subject:

http://www.popularmechanics.com/flight/a9787/airship-of-dreams-lighter-than-air-travel-is-back-16292687/

Note that the Square-Cube-Law also helps airships resist being pushed around by wind a bit- as larger airships present relatively less Surface Area for wind to act on.  The problem still grows in absolute, though not relative, terms however- so an awareness of which way the wind is facing,  large rudders and other control-surfaces, and taking off with the airship pointed parallel to the wind is still extremely important in most situations...

Finally, see this Telegraph UK article on the return of airships.  It's somewhat outdated, but provides a bit more historical context...

http://www.telegraph.co.uk/news/science/8252162/The-return-of-the-Zeppelin-not-just-a-flight-of-fancy.html

 

Regards,

Northstar

 

Edited by Northstar1989
4 people like this

Share this post


Link to post
Share on other sites

Note that I'm pretty sure you only have square-cube advantages to blimps.   Rigid dirigibles (like Zeppelins) presumably need to hold themselves together without a buoyant gas and thus lose all the advantages.

Don't underestimate the power needed to deal with the aerodynamics either.  They may get all the square/cubed from size, but still need to overcome the wind plus any speed you need.  I've heard the Goodyear blimp go overhead and it is *LOUD*.

Share this post


Link to post
Share on other sites

Posted (edited)

8 hours ago, Northstar1989 said:

particularly thanks to the Square-Cube Law (which in this case means that for an airship with a given envelope thickness the total mass of the envelope only increases with the square of the dimensions

If the envelope is one big bag, its wall thickness must grow as well because:
1) The stress is proportional to the radius of curvature, i.e. to size, and inversely  proportional to the envelope thickness.
2) All stuff is hanging on the balloon spine.

If (afaik as usually) the envelope just holds together numerous ballonettes, their thickness would stay the same. But their amount (ergo, their total mass) is defined only by the cargo weight. So, the enevlope mass again grows as fast as cargo.

So, not "square", but just "slower than cube"

 

8 hours ago, Northstar1989 said:

Note that the Square-Cube-Law also helps airships resist being pushed around by wind a bit

How big would be a balloon to carry Boeing-747? How much is its total area?

28 minutes ago, wumpus said:

square-cube advantages to blimps

See p.1. If your blimp has the same thickness for 100 and 1000 t craft, that means you've overthickened and overweighted the former one.

28 minutes ago, wumpus said:

Rigid dirigibles

.... are same elastic bodies. Just with another rigidity factor.

Edited by kerbiloid

Share this post


Link to post
Share on other sites
11 hours ago, Northstar1989 said:

So, there has been a lot of excitement in the past few years about certain companies working on new, modern, ultra-large cargo airships- most notably the Aeroscroft designs, the largest of which may be able to lift 450-500 tons!


Only among people with the memory of a goldfish, the rest of us remember the last fifteen times companies were working on "new, modern" cargo airships of various kinds and how they went precisely nowhere.  Every five to eight years since (roughly) the mid 60's, somebody with more money than sense discovers airships...  With great fanfare they announce a new designs and there's tons of cool concept art of lovely silvery whales cruising serenely through the sky.  Many of the even get so far as producing flying hardware...  and then reality sets in.

There's no market for them.  They're a solution in search of a problem.

Though they're compared to aircraft (because they fly), they're not actually competing in the same market.   Aircraft handle cargos that are speed sensitive, a market segment airships cannot compete in.   Cargos that aren't speed sensitive (and all bulk cargos) go via ships, trains, and trucks - and airships aren't particularly competitive in that market.   There's significant capital investment plus considerable infrastructure investment...  and airships are vulnerable to weather conditions that do no more than require the crews of competing modes to don a light jacket.

They could compete in underdeveloped parts of the world, but those parts of the world have insufficient demand for cargo in the amounts airships carry to offset the entry costs.  They could compete with heavy lift aircraft, but that market is pretty small and well served by existing vehicles.  The low speed of the airship also means you'd need more of them to service the existing demand - running smack into the same entry cost wall.  The DoD keeps looking at them, but they keep running into the same problems as commercial operators, they're insufficient replacements for existing modes while having significant vulnerabilities and a high entry cost.

3 people like this

Share this post


Link to post
Share on other sites

Posted (edited)

Even if imagine a superzeppelin carrying 50 000 t facility to grizzlies and penguins where no railroad, no seaport, when this facility will start, it anyway will require full logistics infrastructure.
So, you can build the road first, then deliver the jumbo by trains.

Spoiler

Unless it's named Kirov

14165122246321.jpg

 

Edited by kerbiloid

Share this post


Link to post
Share on other sites

Posted (edited)

Maybe operating large, slow things isn't the way forward anymore ? From a transportation standpoint, unless the goods / cargo are very, very resistant to changes (of physical characteristics and value), it's better to have a quick transport even in small amount (though large, quick transport would be the golden prize) and for the ones that's really resistant it's still better again to just have a pack of small, slow things (so they become large) or a larger and slower thing as well (in this case, land transport or water vessels).

Edited by YNM
ignore the "news", wrongly reads the date

Share this post


Link to post
Share on other sites

Somewhat related:

What about a "big" telescope in a high altitude blimp? To overcome atmosphere extinction, overcome seeing and be able to see in wavelengths impossible in the surface, without the need to be in orbit and the capability to have maintenance be upgradeable.

It maybe is stupid, I'm very tired today.

Share this post


Link to post
Share on other sites
8 hours ago, kunok said:

What about a "big" telescope in a high altitude blimp?

A huge elastic blimp with a telescope: trembling, rotating after every wind blow, beneath the rest of the atmosphere, with unpredictable position and orientation.

P.S.
Also, a railway, airlines, cargo truck company are expensive, but they bring money to the owner every day.
While a megazeppelin would wait for Santa to carry its total payload (1000 t of presents for all good children) at once.

Share this post


Link to post
Share on other sites
16 minutes ago, kerbiloid said:

A huge elastic blimp with a telescope: trembling, rotating after every wind blow, beneath the rest of the atmosphere, with unpredictable position and orientation.

Welcome to the 21st century - where telescope mounts that can trivially compensate for such things have been common for decades.

1 person likes this

Share this post


Link to post
Share on other sites

Posted (edited)

20 minutes ago, kerbiloid said:
8 hours ago, kunok said:

What about a "big" telescope in a high altitude blimp?

A huge elastic blimp with a telescope: trembling, rotating after every wind blow, beneath the rest of the atmosphere, with unpredictable position and orientation.

We have SOFIA. Unless a blimp is much, much more unstable than airplanes I don't see a difference - if anything, a blimp can be a better platform (fitted with the right propulsion systems it may be able to pretty much sit there all the time. yes unless it's jet stream.)

20 minutes ago, kerbiloid said:

While a megazeppelin would wait for Santa to carry its total payload (1000 t of presents for all good children) at once.

If all the children are in China and Santa is in Finland, it's sensible. (but ships are better already in this case, availability wise.)

Edited by YNM

Share this post


Link to post
Share on other sites

Posted (edited)

11 minutes ago, DerekL1963 said:

Welcome to the 21st century - where telescope mounts that can trivially compensate for such things have been common for decades.

Welcome to the 20th century - where telescope mounts are still either mounted in concrete or are orbiting the Earth far from the air flows.

10 minutes ago, YNM said:

Unless a blimp is much, much more unstable than airplanes I don't see a difference - if anything, a blimp can be a better platform

A hundreds-meters balloon with a hudreds-meters rope with a 10 t hubble below, trembling and rotating, floating with unpredictable winds changing every hour, moving up and down with air flows, with a half of the view field closed by the balloon itself?

Btw how would they send a repair team? Airplane can't, rocket can't. Only on lesser zeppelins. The docking of two zeppelines 40 km above the Earth would be a magnificent show.

Edited by kerbiloid

Share this post


Link to post
Share on other sites
7 minutes ago, kerbiloid said:

A hundreds-meters balloon with a hudreds-meters rope with a 10 t hubble below, trembling and rotating, floating with unpredictable winds changing every hour, moving up and down with air flows, with a half of the view field closed by the balloon itself?

Was to reply "if the whole thing is on top instead ?", but I guess structural gets in the way here.

Still, are blimps more / less "bumpy" than airplanes ? I mean, SOFIA is on an airplane, and airplane also gets turbulence etc. right ? Also, I was thinking something along a system to keep the whole thing resists the wind changes - somewhat like RCS on space probes.

Share this post


Link to post
Share on other sites

Posted (edited)

9 minutes ago, YNM said:

Still, are blimps more / less "bumpy" than airplanes ? I mean, SOFIA is on an airplane, and airplane also gets turbulence etc. right ? Also, I was thinking something along a system to keep the whole thing resists the wind changes - somewhat like RCS on space probes.

An orbital telescope doesn't need fuel at all. Gyrodynes, solar panels and no air drag.
While any flight of SOFIAscope requires, I guess, several tons of fuel.

Also the higher is telescope to make the view clear, the thinner is air around, the less efficient are propellers and jets. Also don't forget the plane vibration.

Edited by kerbiloid

Share this post


Link to post
Share on other sites

Posted (edited)

4 minutes ago, kerbiloid said:

An orbital telescope doesn't need fuel at all. Gyrodynes, solar panels and no air drag.
While any flight of SOFIAscope requires, I guess, several tons of fuel.

Also the higher is telescope to make the view clear, the thinner is air around, the less efficient are propellers and jets.

Orbital probes takes waay more fuel during launch than a handful of plane operations. (and more (initially) expensive, un-service-able and un-upgrade-able, or takes a lot more money to do so.)

Noted on the engines, thanks. But I suppose all boils down to size, we're not talking mesosphere here, still stratosphere.

SOFIA's primary mirror is the same size as HST's.

Edited by YNM

Share this post


Link to post
Share on other sites

Posted (edited)

4 minutes ago, YNM said:

Orbital probes takes waay more fuel during launch than a handful of plane operations. (and more expensive, un-service-able and un-upgrade-able, or takes a lot of money to do so.)

Say, a Falcon of kerolox means ~=150 t of kerosene. I guess, several tens flights of Sofia, .several hundreds hours of observations. While an orbital scope means tens thousands hours per the same spent fuel.

Edited by kerbiloid

Share this post


Link to post
Share on other sites

HST needed 5 shuttle launch to keep it alive until today. (but it does deliver more things back in turn, I suppose.)

Share this post


Link to post
Share on other sites

Posted (edited)

6 minutes ago, YNM said:

HST needed 5 shuttle launch to keep it alive until today. (but it does deliver more things back in turn, I suppose.)

But unlikely refueling. And it was the first. 
Modular design rules. And large series. And the 21st century thing - a simultaneous coordinated work of a telescope constellation like one, in thousands km from each other (by definition unavailable for the aeroscopes).

(Also the first Hubble mission was caused only by somebody's curvy arms. Literally - when they delivered a lens to correct the mirror with wrong curvature or so.)

Edited by kerbiloid
1 person likes this

Share this post


Link to post
Share on other sites

Posted (edited)

Off/T :

32 minutes ago, kerbiloid said:

(Also the first Hubble mission was caused only by somebody's curvy hands. Literally - when they delivered a lens to correct the mirror with wrong curvature or so.)

This went wrong when they made it : https://en.wikipedia.org/wiki/Null_corrector

And yes, interferometry rules ! You can even have backyard interferometry telescopes if you want :wink:

EDIT : Look at this !

That's like, they're doing LISA on a 747 round whole telescope !

Edited by YNM
1 person likes this

Share this post


Link to post
Share on other sites
20 hours ago, DerekL1963 said:

Though they're compared to aircraft (because they fly), they're not actually competing in the same market.  

The hope is to replace helicopters.  This is why they typically start by looking for military customers (who are already prepared to ship things via helicopter).  Even this shows little sign of working as the market for cargo helicopters is vanishingly small.

Share this post


Link to post
Share on other sites
10 hours ago, kerbiloid said:

Welcome to the 20th century - where telescope mounts are still either mounted in concrete or are orbiting the Earth far from the air flows.

Yeah.  Unless they're mounted in an airplane.   (And 2017 is in the 21st Century - so, you're way out of date.   Seriously, the problems you list are long, long solved.)

Share this post


Link to post
Share on other sites
22 minutes ago, DerekL1963 said:

Unless they're mounted in an airplane.   (And 2017 is in the 21st Century - so, you're way out of date.   Seriously, the problems you list are long, long solved.)

How many telescopes are currently flying on planes, and how many telescopes are currently being built on ground?

Share this post


Link to post
Share on other sites
20 minutes ago, kerbiloid said:

How many telescopes are currently flying on planes, and how many telescopes are currently being built on ground?

That's a completely irrelevant question - what we're addressing here is your implied claim that balloon borne telescopes are not possible.   Which claim you should address by simply googling "balloon borne telescope".  That'll lead you to a ton of sites describing flown and flying systems, contact them and tell them they're lying and what they're doing is not possible.

Share this post


Link to post
Share on other sites
19 minutes ago, DerekL1963 said:

that balloon borne telescopes are not possible

They are possible. Also humans can build their homes on trees, but usually they don't. Efficiency rules. Orbital telescope sleeps in bed and doesn't eat. Airborne one just makes problems where they weren't.

20 minutes ago, DerekL1963 said:

That'll lead you to a ton of sites describing flown and flying systems

Sites are nice, but existing crafts are better.

Share this post


Link to post
Share on other sites

Posted (edited)

There is at least one airship company planning on servicing mines in the far north like the Northwest Territories or Nunavut, where roads are few and unpaved and rails are nonexistent. Heavy-lift airships would make it cheap to move ore to railheads or ships in the Northwest Passage. 

Edited by StrandedonEarth

Share this post


Link to post
Share on other sites
4 hours ago, kerbiloid said:

They are possible. Also humans can build their homes on trees, but usually they don't. Efficiency rules. Orbital telescope sleeps in bed and doesn't eat. Airborne one just makes problems where they weren't.

Whatever.    Here in the real world, balloon borne telescopes are useful and common.
 

4 hours ago, StrandedonEarth said:

There is at least one airship company planning on servicing mines in the far north like the Northwest Territories or Nunavut, where roads are few and unpaved and rails are nonexistent. Heavy-lift airships would make it cheap to move ore to railheads or ships in the Northwest Passage. 


So how are those mines moving ore now?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0