The huge LEMV* surveillance airships now being built by British designers for the US Army may be able to carry substantial cargoes as an alternative to sky-spy equipment, according to reports. The LEMV airship to be built for the US Army. Credit: Northrop/HAV Might not just be a spy-eye but a sky truck, too. Aviation Week, in …
If the machine is appropriately shaped and compartmented then could additional lift be provided.
I'm thinking hear of making it a bit 'wing shaped' with retractable stubs into which helium could be expanded as height increases.
It may not have enough power in its own engines to drive it forward to get aerodynamic lift, initially, but a winch or tow plane (or 2 or 3 or many drones) may do the trick. Once Airborne then it has 3D to move in.
Will the upper surfaces be equipped with PV solar cells to recharge the batteries/fuel cells for the electric motors or H2 fueled engines?
Shows you how little I know, I guess.
A metric tonne?
Half a billion dollars to move three tonnes?
How could this possibly be worth bothering with?
Hate to think of the depreciation on that
Using a Trebuchet for transport would be equally silly and much cheaper!
And more fun
Just think about how many dead cows you can throw!
Excuse me sir, but using a Trebuchet for transport is anything but silly!
Definitely cheaper though as you say
All that technology...
It always amazes me that simplistic solutions always seem to be adopted, even when they compromise the outcome.
Rather than trying to manage the quantity of the gas by setting it at launch, why not have a small compressor and pressure vessel on board? As the craft gains height, helium could be extracted from the envelope and stored in the cylinder.
As the craft descends, the stored helium can simply be added back to the envelope to re-establish buoyancy,
This is just the same sort of control that a diver uses in water - except that divers vent gas from the buoyancy cell(s) on ascent, rather than trying to scavenge it. But that's because carrying a compressor would not be feasible. We're not airships...
"offloading a big cargo would still probably call for taking on a lot of ballast, which might be hard to arrange at many Afghan bases"
I believe they have plenty of rocks there.
I hate to disagree with you but.
There's no reason why mini compressors can't reduce the mass of helium in the bags, to increase the ceiling height. Submarines have used this technique for a hundred years.
Someone please explain:
Why can't you outfit a helium-filled blimp with one of those miraculous devices that take gas and compress it, storing it into pressurised gas containers? That'd save venting the spendy gas, and enabling its use for another day, or another descent maybe.
Me, I wouldn't mind trying to run the thing on hydrogen. It's not a passenger craft, you know.
The reason why compressors are impracticable in helium balloons is simply because compressing a large volume of gas quickly requires a huge amount of power and heavy weight equipment. Then you need high pressure tanks to store the compressed gas. Any compressor light enough to be carried on an airship without hopelessly compromising payload capacity is going to be nothing like powerful enough. The volumes of gas involved are simply enormous measured. You would need to be able to compress hundreds of thousands of litres in a matter of several 10s of seconds.
A compressor with a total swept volume capacity of 10 litres (which would be fairly big) would require 10,000 strokes to suck in a 100,000 litres (which would probably take a few minutes), and you'd need multi-stage to get it down to a decent volume. and the whole thing would need a lot of power plus fuel and weigh rather a lot.
That's why compressors haven't been used in Airships and ballasting/venting are preferred. The position with subs is not the same. Volumes are much smaller, weight isn't a problem and there's usually plenty of power available. Water has the great advantage of being pretty well incompressible. The atmosphere is anything but.
Thanks. It doesn't exactly answer what the weight ballpark would be, but "too heavy" is clear enough. Since we're talking large and slow-ish things, ten minutes to compress enough of the volume to stop the buoyancy-providing bubble from bursting while ascending sounds reasonable, as in not prohibitively slow, at least to my layman's ear. Then again diesels have become light enough for aircraft use not too long ago so maybe this might be fixed some day too. Or, I dunno, systems with lasers forcing the helium molecules into high-pressure store one by one, who knows. Crazytech, eh.
Practicality of compressors revisited...
There's plenty of stuff around compressors on airships. It has been a subject of research and pretty well every designer has decide it is impractical. Every now and then somebody floats (pun intended) a maverick idea, but nothing much comes of it. Do some research on the Internet and you'll find this type of stuff.
As for the weight - measured in the region of several tonnes. As far as time goes, an airship can rise an awful long way in a couple of minutes. There are cases in the old, pre-WWII days, of airships rising many thousands of feet in a minute despite venting hydrogen, which is a lot faster than any practical compressor could achieve. Airships are not only vulnerable to the expansion of their lifting gas as they rise, but also to relatively minor changes in air pressure due to variations in local atmospheric and weather conditions.
Generally using thrust to force the airship down is going to be more efficient than trying to balance bouyancy through compressing relatively large volumes of gas. However, once you lose control then there will be no choice but to vent as nothing will deal with the situation fast enough.
Not quite so bad?
If you run a compressor only for saving helium after offloading, maybe you can afford several tens of minutes rather than several tens of seconds.
If you are doing repeat deliveries, the first item to be delivered could be the compressor, which you keep on the ground at the destination. Subsequent runs don't have the weight penalty of carrying a compressor. On the last run you wreturn with the compressor as (partial) ballast.
The yanks are looking at compressors
The compressor idea is not impracticable, the yanks have been looking at it for a few years now. They have been looking at it from using it for freight.
Look at it this way in a commercial freighting arrangement once the airship has landed the compressors don't even need to be on the airship they can be ground based and powered from a ground based source. This would be the equivalent of taking on ballast except the ballast is in the form of compressed He in pressure tanks.
Re: Someone please explain:
"wouldn't mind trying to run the thing on hydrogen. It's not a passenger craft, you know."
But it is a military vehicle, and tracer is much less effective against helium
Yes, tracers might be a spot of bother. But even so, what if you'd make the container fabric self-sealing (like military fuel tanks) and fire-retardant (like commercial airline interiors or better)? Hydrogen still needs oxygen to burn.
Option 2 - I hear they have some sand over there, equip it with an industrial sized "no-loss-of-suction" dyson, along the lines of that capital ship in Spaceballs ;-)
Why not pump the helium into compressed containers? It's well known that helium seeps out of just about anything, but if you were to compress it to a matter of 5 to one, you'd save on venting the stuff and be able to trim the height.
Does anyone else see
a giant, floating, pasty white arse???
No ballast available?
How about good old sand bags. Pretty simple to arrange, even in Afghanistan.
Does my bum look big in this?
I remeber seeing the first Ford Ka and thinking someone had taken a normal car and inflated it with a bicycle pump.
This "cargo lift" capacity is in the same class as the "need" for cross-range capability in the Space Shuttle was: an idiotic and unnecessary waste of development funds.
Use this thing for what it was originally intended, and either use a current cargo lifter or call for a new design for one.
The cross range capability of the Shuttle was by far not the most dangerous or unreliable aspect of the craft.
The biggest problem with the Shuttle was it's launch system and the tendency for things to fall off of it or to explode. I am not the first person to point this out here.
Two words: O ring.
Who mentioned danger or reliability?
and I may not be the first person to point out that your answer has no relevance whatsoever to the point that was made.
The comment was that it's generally cheaper and easier to make dedicated craft for each required purpose, rather than wasting time & effort making a multi-purpose craft that fulfills none of the roles particularly well.
HAV 304 and Skzcat.
The HAV 304 that Hybrid Air Vehicles in Blighty are developing for the LEMV contract is designed primarily for medium altitude surveillance, however the military do like multi role vehicles and it can be changed over to a cargo transport fairly easily. If however the primary purpose of the HAV was cargo then a slightly different design called the Skycat will be used. The Skycat is similar to the 304 but will have larger engines and a slightly different hull and hoverskirt arrangement, for roll on roll off and an even larger static weight range as a result.
Regards JB ( www.hybridairship.net )
Answers to some comments on HAV's.
Some rather odd comments that need a few answers so here goes:
Firstly the HAV 304 is a hybrid air vehicle, which means it is a cross between a blimp and a flying wing plus a hoverskirt undercart. It does not need wings and a layer of PV panels would not justify their weight or work too well in Afghanistan. The amount of Helium is fixed and it does not need to be changed unless there was a big configuration change such as changing from medium altitude surveillance to low altitude heavy lift. Then the Helium would be topped up to increase payload, otherwise almost no Helium is required after initial inflation. All military aircraft have to use JP8 fuel which is a cross between jet fuel and diesel. Hydrogen could be used in a civil version but the present engines are Centurion 4.0 diesels which are very efficient anyway.
Secondly the 517 million dollars was for 3 HAV's not one and half the cost is for the special surveillance payloads. Initial prototypes are always expensive but a production HAV will cost less than an equivalent aircraft and far less to operate in fuel terms.
Thirdly forget about storing or compressing Helium and other research programs as they are all too heavy to be useful at present. Due to it's high static weight capability an HAV does not need such systems.
Fourthly the ballast question only applies to normal airships not to HAV's as they can take off heavy enough to avoid a light landing. Even if an extreme condition did arise then sandbags can always be loaded into the cargo bay.
Regards JB ( www.hybridairship.net )
Of course there'd be odd comments.
But thanks for the clarification anyway. So no venting (which was speculated about in the main article, btw). The hydrogen comment was about floating it with hydrogen, not necessarily using that as fuel (but if you have it anyway... but I digress). And, well, we've been told on a couple occasions that extremely light-weight and bendable sheet-like PV is coming our way, and if anything an airship doesn't have a shortage of it's area, so the connection is fairly natural to make. Whether it's viable after all is another thing, of course.
But what I'd really like to know is about the carrying capacity of this thing. Can you give us some numbers, like what happens if you reduce the mission time to, say, one week and drop all the excess kit and fuel, maybe drop the ceiling a bit. How much can it carry then? How far will it go in that time with that cargo?
I'm confused (again)
So these airships can only land by using upward thrust from the engines as they are heavier than the bouyancy of the gas bag. I presume that having landed that then the engines are put into either no up thrust or down thrust to maximise the negative bouyancy. You then claim that the weight penalty of a compression system would be excessive, but why not use the drive engines as compressors, seeing as how they are not needed for lift when the airship is on the ground? This is easily done by using one bank of the V8 as an engine to drive the other bank as a compressor. Half of a 4 l engine running at 3000 rpm will compress at least 3000 litres of gas to 150 psi per minute, 4 engines will compress 12000 litres/min.
The next problem is the weight of the storage system. No problem at all as soon as one stops thinking about dedicated and heavy cylinders. The floor of the cargo deck needs to be strong enough to handle the cargo, and the lightest way of getting the strength is to use extruded box section alloy. Connect all of the box sections together and use that as your storage "cylinder". Compression and storage of excess He for practically no weight penalty.
It just requires a little thinking outside of the norm.
Thinking outside the norm.
There is reasearch into Helium compression for ballast control of normal blimps, but although they have got the weight of the compressor and power source within reasonable limits, the bottle is a different story as any kind of metal cylinder is too heavy and the composite cylinders explode in a fire or if they get hit with a high velocity round. No way at present as it would be like flying with a potential bomb.
For a hybrid air vehicle there is no requirement for ballast due to the lifting body allowing very heavy take offs using aerodynamic lift with a short take off run. Vectored thrust is also used to help but most of the gain is pure arodynamic lift and as only 30 kts is the sort of speed required the take off run is very short and any flat surface will do.
Regards JB ( www.hybridairship.net )
Can it handle mobile (US: cell-net?) phone calls?
If so I'd guess it has at least a reasonable and justifiable existence as a mobile comms centre maybe better enhanced if it supported multi-national capabilities?
Uh? Massive? El Reg, stop exaggerating!
'Massive new US spy airship 'could be used to carry big cargoes'.
Uh? Massive? El Reg, stop exaggerating! In English, 'massive' means 'massive' -- as big as or bigger than the biggest.
This airship is a toy when compared to the Hindenburg, for starters it's a puny 300ft in length, the Hindenburg was over 800ft--and, to boot, it was built over 74 years ago out of crappy materials. A few stats here:
(Always knew IT types either failed history or never studied it.)
Is this a joke?...
Whats going to stop someone shooting a bullet at it and making it fly around the sky like a balloon? Or more seriousy whats to stop someone sending an RPG right at it?... I imagine it would be pretty difficult to miss....
No real worries about getting shot down as the HAV 304 normally operates at 20,000 ft and Bin Laden and his boys don't have anything better than a Russian heavy machine gun, which is good for about 5000 ft. It would be good if they did try shooting though, because it gives away their position to the targeting folks. Even if they manage to buy and import larger IR homing missiles, they will find they just wasted a bunch of money as the 304 has diesels that won't give a good enough signiture for a lock, even on the ground runs. In reality they will be much harder to shoot down than a helicopter.
Regards JB ( www.hybridairship.net )
@Noviz - Airships are much harder to shoot down than you'd think
I agree with 'heliumblimp', airships are much harder to shoot down than you'd think.
In WW-I there were many accounts of where German airships over London were shot at and the bullets passed right through them without significant damage. Even filled with highly flammable hydrogen, the airships did not catch fire. The only damage to the ship was to the gas cells (bags) that were specifically hit, these simply lost their gas (hydrogen). As there were many gas cells, the buoyancy lost by bullets passing though a few bags was small; even then--with a cell taking a finite time to deflate--any noticeable loss of buoyancy only occurred after the ship had left the combat zone.
It was not until the British developed incendiary 'bullets' that would specifically catch the hydrogen on fire that airships were very vulnerable.
However, today, any such airship would use helium and not hydrogen, thus both bullets and incendiary shells would have little effect. In fact, the cellular nature of the airship combined with helium and the use of modern materials not available back then, would make the airship quite a formidable device (especially so given that its size and large lifting capacity would also allow it to be extremely well armed both with attack and defensive weaponry).
Unlike a plane, even if hit with a missile and badly damaged, its large size and that it's mostly cellular 'packets' of helium, large parts of it would likely remain buoyant (at least until it could escape the danger zone--as did the German Zeppelins of WW-I).
Combine the airship's intrinsically buoyant properties with an operationally redundant design (i.e.: where multiple copies of operational systems are widely distributed across the airship) and it's likely to still function, even with significant damage.
Thanks for both of the good answers :) Wasn't expecting it! haha
In order to bring down a helium filled airship you need helium tipped bullets.
The helium tipped bullet hitting the helium gas causes the helium to fuse and create a chain reaction causing the helium at 0.1786 g/L to convert to carbon at ~2.3 g/cc, causing an almost instant implosion of the gasbag and the generation of an additional very strong negative lift.... as the 1000 cubic meters of helium converts to 120Kg of carbon....
One bullet downs one airship.
a plan so cunning...
If the engines are able to thrust both upwards and downwards, would this in part negate the problem of it becomming uncontrolably bouyant (sp?) once it's offloaded its cargo?
Static weight issues.
It does help to have full function up and down vector for the main engines of a normal blimp like a Skyship has, but for a hybrid air vehicle it does not matter, as they are shaped like a flying wing, albeit a fat one and produce so much lift with a short take off run that they can start so heavy that the finishing up light and having to valve off Helium problem, no longer exists. That is why the US military chose a hybrid design.
Regards JB ( www.blimpingaround.com )
why is such a short article divided into two pages?
It's especially silly as the asterisk on the first page refers to a note on the bottom of a second page.
Encumbering readers with this sort of unnecessary bother is a travesty, I tell you! A travesty! I've half a mind to delete The Register from my bookmarks.
are so 1999
Lots of rocks
Assuming you don't mind moving dirt around, there's usually a few rocks or a little bit of sand nearby most US bases.
@ JonB - I expect that's rather cheaper than arranging spy satellite coverage of a similar area (non-stop) for 3 weeks.
LEMV are go!
I see no reason why they shouldn't paint this thing green and call it Thunderbird Two. That way it'd be so much easier to control the altitude, because it'd be on strings.
I can almost sense a Lewis Page airship compressor strop coming on....
When offloading in Afghanistan, could one of these ships fitted with some oversized shopvacs simply slurp up some sand and rock? You'd only be able to unload where the ground is sandy, but that might be plenty of places over there...
Paris, because she'd suffer no such restrictions...
Maybe this is sillly...
But it seems to make more sense to use hydrogen. Then you can effectively convert between lift and ballast using fuel cells in conjunction with atmospheric oxygen.
It also means that if you need to get rid of lift in a hurry you can dump the hydrogen and make more from water later.
yes, but ...
... if it had more than one bag and only the top one was hydrogen, and the rest was helium, then perhaps it would be a workable idea.
@Purple People Eater - Reckon it is silly.
Reckon it is silly. As I said in another post, the German WW-I Zeppelins over London weren't vulnerable to bullets but they were so when the British eventually developed incendiary fire.
History has shown that significant damage can occur to an airship without its hydrogen catching fire but when it actually does then it's absolutely catastrophic. Despite it's few disadvantages*, helium has one incredibly important feature which is that it's chemically totally inert--nothing short of nuclear fission will make it 'burn'.
Formula learned for history:
Airships + H2 = Madness.
* If I recall correctly from my physics days, in practice, helium has about 6-8% less lift than hydrogen. Experts, correct me if I'm wrong.
BTW Purple People Eater, with that alias you must be a refugee from 1958, Sheb Wooley et al. Oh, perhaps too, you're very one-eyed on many issues. ;-)
Formula learned from hysterical radio reporters live-on-air. The H2 didn't mix with air to supersonically go boom. It just burned, and the ship came down placidly. Most deaths, in fact, were from panicked people jumping from 30 metres up. Looking at the death toll and comparing it to a "much safer" kerosene-filled sardine can^W^Wairliner crash, and keeping in mind they've had some century or so to improve upon fire safety.... I'd like to see that hydrogen-floated blimp with the benefit of a hundred years of airline fire safety applied.
Wikipedia claims 8% and calls the difference neglible. Time in a 1924(!) piece claims:
``The total lift of a helium-filled dirigible is accordingly some 10% less than that of the hydrogen-filled airship. The difference does not appear important at first sight, but the total lift of the gas carries the structure, the motors and the crew. It is only the last 20% or so that is available for carrying fuel, and hence a difference of 10% in the gross lift may spell a difference of 50% in the fuel-carrying capacity. On long-distance flights this difference is vital.''
Only Bin Laden himself thinks the LEMV should use hydrogen!! The last thing we need is a Hindenburg mk 2. It would make the HAV very vunerable to sabotage on the ground, silly accidents by engineers or lightning strikes. Helium is the only approved lifting gas for airships and no one is talking about any changes at present.
Regards JB ( www.blimpingaround.com )
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