Lighter Than Air versus winged designs for high altitude

S

sublight

Guest
Anytime somebody says "higher and longer" they should be talking LTA. Winged lift designs cant even come close.
 
unless you are flying below 60,000', the winds will kill the lighter than air idea. Above 60,000', for any reasonable payload weight, you need, oh, about a million (yes, 10^6) cubic feet of helium in your envelope.
 
AeroFranz said:
unless you are flying below 60,000', the winds will kill the lighter than air idea. Above 60,000', for any reasonable payload weight, you need, oh, about a million (yes, 10^6) cubic feet of helium in your envelope.
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Well that would certainly fall in line with the mythic "stealth blimp's" gigantic size wouldn't it? :)
 
AeroFranz said:
unless you are flying below 60,000', the winds will kill the lighter than air idea. Above 60,000', for any reasonable payload weight, you need, oh, about a million (yes, 10^6) cubic feet of helium in your envelope.
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Anyone designing LTA craft to operate for several decades into the future had better design for hydrogen, not helium. Chances are good that we will see the end of cheap helium relatively soon... a decade or less. So given the glacial pace of aeronautical development these days, any new program that baselines helium will probably find itself well and truly screwed.
 
Hydrogen by itself would give about 10% better specific lift, not too shabby. There will always be people bringing up the whole Hindenburg deal, but with current materials i don't see why it shouldn't be perfectly safe. For an unmanned vehicle that stays up at 65,000' for months/years, it's a no-brainer...but that's just me. Use hydrogen burning engines or regenerative power, and you don't even have to worry about changes in buoyancy versus weight.
 
flateric said:
Boeing Unveils Unmanned Phantom Eye Demonstrator
ST. LOUIS, July 12, 2010 -- The Boeing Company [NYSE: BA] today unveiled the hydrogen-powered Phantom Eye unmanned airborne system, a demonstrator that will stay aloft at 65,000 feet for up to four days.
# # #
Photo credit: Boeing photo


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LTA platforms are much better suited for this role. The only reason the Air Force keeps asking for high altitude winged systems is because they are deathly afraid the LTA craft will siphon off the satellite budget. Because LTA is that damn good...
Have a look.... http://www.youtube.com/watch?v=ojGcX2H81NQ
 
I'd like to apologize in advance to the site owners, moderators and contributors for this, since it doesn't have any direct relevance to the Phantom Eye demonstrator. But enough is enough.

Sublight,

I fail to see how LTA platforms have any relevance to Boeing's HALE concept.

You have tried to tie your "Stealth Blimp" beliefs to countless topics over the past few years without contributing any factual information to the subjects at hand. You have attempted to link, without a shred of evidence, your theories to the Senior Citizen, "active stealth", Tier III........the list goes on. Your comments, while usually simply a nuisance, have actually derailed useful discussions within the forum.

I'll go ahead and say it - this forum is home to, probably, a majority of the leading experts on advanced projects on the planet, including esteemed aviation writers and artists, world famous engineers, pilots and many others. You have attacked individuals who have contributed more to our understanding of advanced projects than any other group that I am aware of.

This board is dedicated to objective research based on discussion and sharing of verifiable evidence. Information gathered, analyzed and compiled by individuals on this site has been cited by many of the leading aerospace publications in the world - most recently, for information uncovered on the PAK-FA/T-50. More than any other forum or publication, it serves not only to satisfy the curiosity of us aerospace enthusiasts, but more importantly preserves the legacy of the unacknowledged engineers, project managers, and test pilots involved in creating these projects. Their contributions are awe inspiring, but will probably forever live in obscurity due to security classifications and other restrictions. Many of them are no longer with us, and it's certainly possible that some may have even given their lives in the pursuit of this technology. Let's not disrespect their accomplishments, or the stature of the members of this group, with wild speculation based on belief and not any sort of verifiable facts. There are plenty of places where discussion based on fantasy and wishes are welcome.

I believe that it goes without saying that this is not the place for this.

Once again, I apologize for this rant, but it had to be said.
 
I think criticism of the phantom eye is warranted, and the Air Force's pursuit of very high altitude winged platforms should be scrutinized. The contents of the video aren't some fantasy, the retired air force colonel narrating the video worked for General jumper and I think anybody following this forum will find the extended contents very, very, interesting.
 
This whole concept of backtracking enemies on the ground from very high altitude works well...when there is no cloud cover.
 
AeroFranz said:
This whole concept of backtracking enemies on the ground from very high altitude works well...when there is no cloud cover.
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"the highly classified Advanced Synthetic Aperture Radar System-2 (ASARS-2) that produced near-photographic quality ground images through the clouds at considerable standoff ranges"

You were saying??? B)
 
sublight said:
"the highly classified Advanced Synthetic Aperture Radar System-2 (ASARS-2) that produced near-photographic quality ground images through the clouds at considerable standoff ranges"

You were saying??? B)
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I was saying...
A) What are the power requirements?
B) How much ground does it cover in a single "frame"
C) How easy is it to track (does it look like a searchlight to a radar-seeking missile)
D) How many images per second

Or in other words... how many hugenormous blimps requiring how many gigawatts of power would be needed to provide complete coverage to something the size of a city with "photographic" quality imagery captured at a rate no slower than a standcard CC security camera?
 
sublight said:
AeroFranz said:
This whole concept of backtracking enemies on the ground from very high altitude works well...when there is no cloud cover.
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"the highly classified Advanced Synthetic Aperture Radar System-2 (ASARS-2) that produced near-photographic quality ground images through the clouds at considerable standoff ranges"

You were saying??? B)
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Your clever plan is missing the step where you give all the bad guys radar reflective tinfoil hats. ASARS-2 (and its successor) cannot accurately track an individual, only groups of persons. It is not very effective at all for the mission you are proposing. If you are going through all the trouble to identify the bad guys at the free hats for insurgents stand, why not just detain them there?
 
Orionblamblam said:
sublight said:
"the highly classified Advanced Synthetic Aperture Radar System-2 (ASARS-2) that produced near-photographic quality ground images through the clouds at considerable standoff ranges"

You were saying??? B)
Click to expand...

I was saying...
A) What are the power requirements?
B) How much ground does it cover in a single "frame"
C) How easy is it to track (does it look like a searchlight to a radar-seeking missile)
D) How many images per second

Or in other words... how many hugenormous blimps requiring how many gigawatts of power would be needed to provide complete coverage to something the size of a city with "photographic" quality imagery captured at a rate no slower than a standcard CC security camera?
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So you are saying a fleet of predators would offer more efficient coverage than an LTA?
 
sublight said:
So you are saying a fleet of predators would offer more efficient coverage than an LTA?
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You know, that didn't seem to answer any of the questions I asked. Or is that some cryptic cypher that if I only knew the key would crank out numbers of gigawatts?
 
sublight said:
So you are saying a fleet of predators would offer more efficient coverage than an LTA?
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Only saying that if there is low altitude cloud cover, it don't matter if you're in a fixed wing, Rotary wing, lighter-than-air, glider, or steam-powered ornithopter for that matter. A sensor operating in the visible light spectrum ain't goin' to do nuthin' for ya.
 
Orionblamblam said:
sublight said:
So you are saying a fleet of predators would offer more efficient coverage than an LTA?
Click to expand...

You know, that didn't seem to answer any of the questions I asked. Or is that some cryptic cypher that if I only knew the key would crank out numbers of gigawatts?
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Since you're Jesus, you are supposed to tell me what the power requirements of the ASARS-2 is.....
 
sublight said:
Since you're Jesus...
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Sigh.

You continue your slide into utter irrelevancy.

Someday you might want to consider thinking about things *critically,* rather than simply lashing out emotionally whenever someone asks you a valid question. Until then...

BabyJesusCry.jpg
 
sublight said:
Since you're Jesus, you are supposed to tell me what the power requirements of the ASARS-2 is.....
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Or you could find out yourself. Google is your friend.
But back to the topic. At very high altitudes LTA craft need much more lifting gas for a given payload.
For the mission you're interested in here, the higher you are, the more electrical power (and antenna) you're going to need. Those two things are in conflict.
To track individuals using radar, you'd need relatively short wavelengths, which demands even more power. Like, enough that the guy you're tracking will burst into flames if he has enough change in his pockets.
 
a (REALLY) large aircraft that's suppose to observe stuff defeats the idea of reconnaissance and covert surveillance IMHO
 
Orionblamblam said:
sublight said:
Since you're Jesus...
Click to expand...

Sigh.

You continue your slide into utter irrelevancy.

Someday you might want to consider thinking about things *critically,* rather than simply lashing out emotionally whenever someone asks you a valid question. Until then...

BabyJesusCry.jpg
Click to expand...
Jesus, I will never get tired of your pithy quips.... You are better than that first cup of coffee in the morning. ;D
 
saintkatanalegacy said:
a (REALLY) large aircraft that's suppose to observe stuff defeats the idea of reconnaissance and covert surveillance IMHO
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Aircraft that *might* be up there somewhere that you couldn't easily see with the naked eye even if you knew where it was, are less intrusive than giant lurlking spybots hanging over peoples heads. Granted, the jihadis are unlikely to be able to bring down a blimp lurking at 60,000 feet... but if everyone not only knows it's there but can actually *see* it's there, and knows it's watching them 24-7, there could well be unfortunate social/psychological responses.

Granted, the British seem to have accepted that if they step outside (especially in, say, London) they will be watched and recorded by Big Brother every second of their lives. But the general assumption is that the watchers are not The Occupying Enemy.

A lurking and visible eye in the sky owned by some nation other than the local one could well make things *worse.* Americans accepted Soviet spy satellites, and probably would have accepted Soviet spy aircraft along the lines of the U-2. But giant Soviet blimps hanging over our cities? Not a chance in hell.

Predator or similar drones, while probably much less capable individually than a massive single blimp, can get in and get out in a hurry, and are difficult at best to see when at operating altitude.
 
High power requirements for an LTA is not necessarily an immediate deathknell.

Lasermotive, one of the intermediate stage winners of the space elevator climber contests, is seriously proposing remote power transmission via laser for military purposes (though admittedly, for applications such as recharging perimeter monitoring sensors via a laser tower in the center of a forward base).


An LTA is as reasonably close to a non-moving target as you can expect for an aircraft. The question then becomes how realistic is it to put a power receiver antenna on the LTA skin surface, both from a direct weight cost and the associated power conversion equipment weight costs.

Lasers would imply a thin film solar cell skin. Efficiencies are still hovering a little over 10% in that category, but the greater issue is upconverting the voltages from the solar panel skin into something useful. Transformer and power control weight is going to be nasty. There would be a secondary heat issue, but that may be more help than hindrance. That said, most of the recent semi-autonomous LTA designs all feature solar cells on the upper third of the envelope skin surface, but that is for solar recharge applications, not the power density of a laser beam (even if spread out to hit a large skin area).

The alternative is a rectenna embedded in the skin. This converts beamed microwave power into electricity directly, and has much higher conversion efficiency. But you may still have transformer weight issues, and now you are bathing your sensor platform in EM, even if you could achieve a tight beam targeting the envelope and not the gondola. The efficiency advantage could win here though, from a weight standpoint.

So you would have an LTA with sufficient fuel to navigate and operate basic systems, but all high power systems are fed by remote power beaming. There are all sorts of neat tricks you could pull if you had that much electricity. Naturally the radar is the primary consumer followed by high bandwidth highly directional communications links, but there could be the potential for laser self defense (no ammo?), electrolysis of onboard water ballast for makeup hydrogen gas, and perhaps using the lasermotive concept of being a power relay and using a laser (reuse the self defense laser?) to supply forward sensors and equipment with recharge power (getting around operational security issues of shining a spotlight on your assets is left as beam steering algorithm exercise to the reader)
 
came across this today...

http://www.theregister.co.uk/2010/07/16/zephyr_7_days/

EDIT- included article text and image.

A British-made solar powered aircraft has been airborne above a US military test range in Arizona for more than seven days continuously, it has been announced.
The "Zephyr", made by controversial MoD boffinry selloff bonanza firm Qinetiq, is still in flight above the US Army Yuma Proving Ground as of publication, having taken off last Friday. At 168 hours as of just before 3pm UK time, this far outstrips the official world record for longest duration unmanned flight (30 hours 24 minutes, set by the RQ-4A Global Hawk in 2001).

In order to make the Zephyr's new record official, a representative of the Federation Aeronautique Internationale (FAI) is present at Yuma. The books will be amended once the aircraft is safely down: however Qinetiq intends to keep it airborne for another week if possible before that.

The Zephyr uses electricity from its solar cells to recharge its batteries during the daytime and runs off the stored power at night. It is intended to carry out surveillance and communications-relay tasks above the battlefield, where it would offer a long-endurance alternative to normal aircraft or satellites.

According to Qinetiq, the goal of the current flight is to show that Zephyr is the world's first "truly eternal plane", capable of staying up for months.

“The team has worked tirelessly over the past few years, making truly significant leaps forward in overall design and construction - and to see it successfully soar into the sky was fantastic,” gushes Jon Saltmarsh, Zephyr chief at Qinetiq. “By being able to remain over a location for weeks or months at a time, it can usefully deliver a host of practical and more affordable solutions to both civil and military customers.”

The new and upgraded Zephyr has been enlarged from previous versions and features a new power-management system and T-tail for reduced drag.

There's no doubt that the current flight is a significant achievement for Qinetiq. However, as with Zephyr's previous unofficially record-breaking flight one can't help noticing that the firm has chosen to make the attempt in uniquely favourable circumstances.

Yuma Proving Ground lies in the Sonoran Desert just 32 degrees north of the Equator, and the northern-hemisphere summer solstice is only just past. The sun is tracking as nearly dead overhead as it ever does over US territory just now, meaning that the Zephyr is getting far more energy from its cells than it would farther north or at other times of year.

One should note that in operational use the Zephyr will have to power a payload as well as itself - and for much of the year in many locations it will have to do this with less output from its cells than it is getting now.

If the sun-plane is generating a large surplus above what it needs to stay airborne, well and good: Qinetiq are offering no details at this point. If it isn't, though, its claim to be the first useful "eternal plane" will look rather unfounded. ®
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cheers,
Robin.

P.S. caption to the image reads "Make the most of it lads, your sons will be doing the next servicing." ::)
 

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I believe the pictures depict an earlier incarnation of Zephyr. The new one has a T-tail and downturned wingtips. Flightglobal might have pictures.
 
ouroboros said:
Lasers would imply a thin film solar cell skin. Efficiencies are still hovering a little over 10% in that category...
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Not exactly true in this case. Such low efficiences are the result of trying to convert *sunlight* into electricity. Sunlight of course having every wavelength imaginable. But lasers are by definition one fixed wavelength. Conversion efficiencies for properly tuned PV arrays can be well over 90%.

As for microwaves... a simple solution to the problem of nuking your payload: use two blimps. One the payload blimp, the other the "power" blimp, connected by a hundred yards of kevlar re-inforced power cable. Float the power blimp directly over the payload blimp. Give the payload blimp some minimal battery backup and some microwave rectenna in case the cable gets severed (wind shear, perhaps), in order to let the payload blimp make it to a safe recovery.
 
The modifications are more extensive than that. Weight, size, and planform have changed.
An article on AvWeek, July 5th, says:

"50% larger wing area, increased span of just over 72ft, and downward canted ogive winglets"
"The 110-lb UAV will carry 6lbs of comms-relay payload"
 
http://www.bbc.co.uk/news/science-environment-10733998


cheers,
Robin.
 
When it goes 9,448 miles non-stop or stays up 264 hours I'll get impressed.... :)

http://en.wikipedia.org/wiki/N_class_blimp
 
Funny thing about solar aircraft is that their performance characteristics vary with location and time of year. It is no accident that the mission is being flown at ~20 deg latitude in summer....
Try this stunt in winter and you probably wouldn't be able to close the daily energy cycle.
 
Funny thing about solar aircraft is that their performance characteristics vary with location and time of year. It is no accident that the mission is being flown at ~20 deg latitude in summer....
Try this stunt in winter and you probably wouldn't be able to close the daily energy cycle.
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See my earlier post on the previous page...


cheers,
Robin.
 
To be truly useful, you need to operate year round at, say, 38 degrees N ;)
 
I'd have said more in the range 30-38 degrees N myself.... ;)


cheers,
Robin.
 

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