Calling our technical experts - Any chance this thing works?

C M Edwards · 2004-05-28 15:48:12

How much money are we talking about? [...]
Not 1000T but maybe just 10kg to LEO?
[...]
Are lightweight solar panels and lightweight batteries the current show-stopper?
[...]
An Ascender needs 5.2 million cubic feet (IIRC based on web articles) and it appears in FY2002 228 million cubic feet of helium was transferred.

At this point, I'm just guessing. All I have is a little knowledge about gas airships and the equations telling me that this should work. I have no connections or inside knowledge of the approach taken by JP Aerospace.

I suspect that a proof of concept vehicle can be launched for less than $20 million US, if you're willing to take the risk of a ground launch (skipping development of a Dark Sky Station).

I don't believe that special "spray on" solar cells or anything else particularly fancy will be required. A large enough solar array of more conventional design can be suspended from the envelope just like everything else on an airship.

The vehicle has to built above some minimum size in order to carry the solar array and batteries for night-time operation of the engine. (The engines have to run 24-7.) I think we're looking at 20 to 50 tons. That's quite massive, but it can be accomodated.

5.2 million cubic feet of helium at an altitude of 42 km is only 25000 cubic feet at sea level. That 5.2 million cu.ft. figure is probably exactly what's needed for a 1.6km long airship, but I think that one could get by an airship using closer to 25000.

Euler · 2004-05-28 18:48:08

The net weight does increase as the vehicle climbs above its equilibrium altitude, but it does not jump from zero to the full displacement at the moment motion starts.

I never said it did. However, the drag is proportional to the air density and to the square of the velocity, and the terminal velocity at the initial altitude is only a few meters/second. The total drag is nearly constant, equal to or slightly less than the thrust of the engines. This means that when the airship reaches an altitude such that the air is 100 times thinner than the initial altitude, it will only be traveling 10 times faster. A few 10s of meters/second is not enough for the orbital velocity to be significant. That means that the airship will have to support 99% of it's weight from dynamic lift.

The lift increases with altitude as well (as a result of greater speed),

No, the dynamic lift is constant, and proportional to drag. The increased speed and thinner atmosphere should balance each other.

The vehicle has to built above some minimum size in order to carry the solar array and batteries for night-time operation of the engine. (The engines have to run 24-7.) I think we're looking at 20 to 50 tons. That's quite massive, but it can be accomodated.

Solar panels are not particularly affected by scaling. If you have 1/10 as many of them, you will produce 1/10 the power. Most batteries are not much affected by scaling either. Ion engines are affected a little, but it is not a huge amount, and the engines themselves will mass much less than the power supply and fuel anyway. I think a proof of concept vehicle could be under 1 ton. It need not reach orbit or carry payload, just get up to a few km/s velocity and a larger version could be considered.

C M Edwards · 2004-06-04 15:54:50

I’m continuing my own analysis of this propulsion method.

It’s capacity is likely somewhat less than my previous estimates, primarily because it turns out that the most obvious configurations can’t be launched from lower altitudes. The vehicle must start from an altitude in excess of 40km. This limits the vehicle mass to less than 200 tons, because that’s about the most that can be lifted into the thin air at that altitude..

Euler, the aerodynamic lift is indeed roughly constant, as it depends on relative velocity and engine thrust. However, there are other sources of lifting force available during the ascent, some of them important for an airship even though they would be negligible for a garden variety airplane.

The airship experiences forces in the horizontal and vertical directions, which can be described as the conventional Thrust, Drag, Lift, and Weight. However, they can be further resolved into: Engine Thrust, Tail Wind Force, Drag, Aerodynamic Lift, Bouyancy, Centrifugal Lift, and Weight. Many of them are variable, and their interplay creates several critical points in the Lift Force curve during the ascent. Those critical points have to occur at a Lift greater than zero, or they can’t be surmounted. Finding parameters that will get the vehicle over one critical point without catastrophically reducing available lift at the next is challenging.

At this point, I can say that the original estimate of 5 days to orbit from JP Aerospace may have merit after all. Wind speeds in the mesosphere and higher approach large fractions of orbital velocity, and the airship is large enough to be carried along with them just like a kite if it can be given the lift to reach them. The centrifugal force of this motion provides additional lift, and the wind force provides far greater acceleration than can be gotten from an ion engine alone. It may even be enough to reach orbit in 5 days.

Losing the ability to lift 1000T to orbit has reminded me that my usual success rate with evaluating such concepts is only about 50/50. However, I still believe an Airship To Orbit vehicle of the type described by JP Aerospace can fly, and with a reasonable payload.

Euler · 2004-06-04 17:49:58

Wind speeds in the mesosphere and higher approach large fractions of orbital velocity, and the airship is large enough to be carried along with them just like a kite if it can be given the lift to reach them. The centrifugal force of this motion provides additional lift, and the wind force provides far greater acceleration than can be gotten from an ion engine alone. It may even be enough to reach orbit in 5 days.

Are you serious about this? I had no idea that there could be wind speeds in the multiple km/s range.

C M Edwards · 2004-06-04 20:29:12

I am very serious. (Fits existing popular models and some limited observations; shouldn't be physically impossible; etc.) A better question would be, "Is this correct?"

I'll have to get back to you after a library trip. I don't have definitive data linking the atmospheric model I'm using back to reality.

Not yet.

mboeller · 2004-06-05 06:32:52

Hi;

based on the ATO-Handhout from JP-Aerospace and the following page [ http://www.grc.nasa.gov/WWW/K-12/airpla … t.html]air density ] I tried to figure out if the ATO is possible or not.

Basics (see link) :
air-density @ 140000 feet = 0,002675 kg/m³
air density @ 200000 feet = 0,000271 kg/m³

From the Handout it seems the DarkSkyStation has 5 fingers each around 2000m long with an diameter of around 125m
So the Volume of the Station is 122718464,8 m³. That means the Station can weigh up to 328 tonnes, which is imho an reasonable figure.

The ATO reaches an max. height of 200000 feet using buoyant lift only. The ATO has only 2 "wings" with an length of around 1800m and an diameter of ~110m ( this is an upper figure, cause as it seems the "wings" look more like real wings in reality ). The Volume of the ATO is < 34211944,5 m³ then.
So @ 200000 feet the ATO can weigth ~ 9280 Kg at the most. If the wings are elliptical then the volume and the buoyant lift is even lower.

IMHO the ~ 9 tonnes for the ATO seems far too low to support an nearly 2km long vehicle with ion drives, fuel, structure, and payload.

So I have to ask, are my calculations correct, or not?

One final remark;

IMHO the ATO cannot use an normal ion drive to reach LEO, cause then the weigth of the fuel would be too much for the ATO.

So maybe JP-Aerospace use an alternative drive. I think two different systems could work :

1,) Ion-Wind Drive. This sort of Ion drive uses the surrounding air as fuel and accelerates this air with HV-electricity to accererate the vehicle. An german university tries to use this sort of engine to propel small UAV's, so imho this is an viable alternative.

2,) Plasma-Skin Drive. This is an real black-world-drive. So far not much is known about it. The Plasma-Skin-Drive is also able to mask an aircraft from radar, so most of the work is done from the military and hidden. I have found only one sourse of open informations : http://jlnlabs.imars.com/plasma/html/s_ … dpthr1.htm I'm not sure if this will even work, but it matches the comments from JP-Aerospace about their drive quite good IMHO.

Josh Cryer · 2004-06-06 07:00:37

IMHO, that movable skin isn't going to work, but I only looked at it a little bit last night, I admit. I mean, if the plasma itself can attract particles, and then speed them up, and then expell them, then it might work, but as far as I can tell, it's just scattering them. I know it may be slightly off topic for this thread, but I'd be interested in others opinion. (Granted, it takes a lot of electricity to run, too, so it might not be viable on those grounds alone.)

Also, mboeller, do you have a link for Ion-Wind drives? I google'd to no avail.

This is one of my most watched threads, though I haven't participated, the thought of blimps to space intrigues me greately.

mboeller · 2004-06-06 11:20:15

Also, mboeller, do you have a link for Ion-Wind drives? I google'd to no avail.

Sure;

One of the best know Ion Wind Drives was called Ionocraft 40 years ago. Here is an really good description of it :

http://www.rexresearch.com/desev/desev. … /desev.htm

I hope you don't mind the overall source, but this page is IMHO really packed with informations.

C M Edwards · 2004-06-08 15:32:24

I’m back from the library, and I still think airships to orbit is a good idea.

However, I am starting to wonder how on Earth JP Aerospace came up with their five days to orbit timeframe.

The projection that led me to expect upper mesosphere windspeeds of more than one kilometer per second is in error. Actual measurements of upper mesosphere windspeeds are hard to come by, because they cannot be obtained by balloon soundings or Doppler radar but require the use of expensive sounding rockets to launch radar targets, and thus are not available on any regular basis. The few actual measurements I was able to find indicate upper mesosphere windspeeds are closer to only a few hundred meters per second – less than 5% of orbital velocity. Theoretically, there should be thermoclines higher in the thermosphere where windspeeds rise into the kilometers-per-second range, but those are at altitudes where the ATO’s terminal velocity would already well exceed orbital velocity and thus are outside the range of interest.

The ATO would still receive a boost in both lift and energy from upper altitude winds, one comparable to that provided by equatorial launch and nothing to be sneered at, but won’t receive enough extra energy from the wind to dramatically reduce ascent time from my earlier estimates. (Not by the amount that the folks at JP Aerospace are talking about.)

Perhaps the folks at JP Aerospace made the same computational error, and put it in their brochure? Certainly there is no way this thing can reach orbital velocity in five days using an electric rocket engine.

Euler · 2004-06-08 16:59:05

Without super high wind speeds, we are back to needing the vehicle to support itself almost entirely from it's dynamic lift. I still have my doubts that this can be done.

Proponents of thin film solar cells claim that they could have specific power values an order of magnitude higher than current solar panels. This could explain some of the higher acceleration of the JP Aerospace blimp. However, I am not convinced that even this would be enough to make the idea workable.

C M Edwards · 2004-06-12 12:06:32

I believe I’ve found out where the extra energy is supposed to come from in order to reduce ascent times to less than a week.

The mesosphere and lower thermosphere experience heating and cooling over the course of the day, causing them to expand and contract on a daily basis (expansion during the day, and contraction at night). This expansion and contraction occurs on a broad scale and is quite dramatic in scope. Continuity (basically, conservation of mass for fluids) requires airflow for the uneven change in volume of that much gas. That means wind. However, the expansion/contraction doesn’t just occur across the day/night terminator but up and down as well. This creates regular updrafts and downdrafts in the upper atmosphere (Upward in the day, downward at night). The air rises and falls on a daily basis, creating a huge wave of thermal expansion that travels around the globe once per day.

An ATO vehicle can ride this wave, gaining energy from it.

These updrafts can reach speeds of up to 100m/s, depending on latitude, altitude and time of year. However, 15m/s to 50m/s appears to be about average. The updrafts start to make themselves felt at 50km and can be observed as high as 250km – well above the altitude where the ATO’s terminal velocity exceeds orbital velocity. The vehicle will not ascend much faster than this during the updraft “crest” of the expansion wave. However, the wing area of the craft is so great that even a relatively slow updraft will carry it heavenward with more force than all the aerodynamic lift it can produce on its own, and a climb rate of 15m/s with an updraft beats the climb rate of 0.05m/s to be expected without it.

This upward boost, once per transit around the earth, lifts the vehicle up to altitudes where its terminal velocity is faster, allowing it to accelerate more rapidly. The boost happens relatively gradually, allowing the vehicle to accelerate up to terminal velocity and maintain lift at its new altitude. The contraction “trough” encountered on the Earth’s night side does create a downdraft and cause the vehicle to descend, but under roughly constant density conditions (no collapse of the gas cells) and does not completely negate the gains in altitude and velocity acquired during the day. It’s able to retain a little bit more energy from each pass of the expansion wave.

The airship is ratcheted into the sky, courtesy of the upper atmosphere’s day/night cycle, obtaining progressively higher altitudes and velocities with each pass. Given that the vehicle doesn’t start at orbital speeds, it may be possible to use a highly inclined spiral trajectory starting at the Earth’s pole to take maximum advantage of this effect, minimizing the amount of time it spends in the wave “trough” and maximizing its time in the “crest”.

The effect is strongest in the mesosphere and peters out near the top of the ATO’s trajectory due to thinning air.

There are still portions of the ascent where the ATO must produce at least 80% of its own weight in aerodynamic lift alone (no centrifugal lift, updrafts, or other sources), and preferably more. One such critical point occurs at the start of the trajectory when its buoyancy peters out before updrafts are sufficient to support it, and the other occurs at the end of the trajectory when the atmosphere is no longer dense enough for updrafts to provide any support. However, the effect of mesospheric updrafts pretty much removes the critical points in between.

If it can surmount these two critical points in its trajectory (and I think it can), an ATO can fly to orbit in less than two weeks.

Timeslicer · 2004-06-19 19:13:09

I think it's worth thinking about the shape of this thing. There are several "mysteries" - why the V shape, why such skinny wings, why make it so huge?

Obviously they're not just aiming for maximum bouyancy - a zeppelin or sphere shape would be best for that.

It's not just drag - a zeppellin shape is more nearly ideal for that.

It's not just dynamic lift - a delta wing shape could give the same lift area with much more volume, hence better bouyancy.

My conjecture is that they need lots of linear length to array their means of thrust - i.e. longer, skinnier wings equals more thrust for a given amount of lift surface and drag. Hence the V shape.

Also, I'd guess that the depth (front to back) of the wings is dictated by their means of propulsion. This makes me suspect that it is some sort of ionic wind system, as some here have mentioned previously. Since that relies on charge separation, there's probably some ideal distance that gets good ionic acceleration per mass of wing cross section - too small and you don't get enough thrust nor enough interior volume for good bouyancy; too large and thrust increases far slower than mass.

They probably also need a lot of fuel to power their ionic engines, which dictates a certain volume of lift cells - which is why it's so huge. And given that the ideal wing cross section was fixed by the above factors, they had to make them longer to get more volume, so they'd have enough excess lift capacity to carry a decent mass of cargo above their fuel requirements.

This craft isn't going to go beyond low earth orbit - an alternative means of propulsion is required beyond that, namely a rocket - and this ship is not structured for rocket propulsion. So they'll either need to carry a rocket vehicle for missions beyond LEO, or meet up with a space tug of some sort. Probably they're aiming to have enough capacity to carry up a space tug in one mission, and fuel and cargo for it in each subsequent mission.

It seems like they could also make these things nuclear powered, but the massive shielding required for a manned craft would still make for a big craft.

BTW - if you've seen the movie Riddick, you may have been struck by the thought that those big floating/flying ships might be designed along these lines...

bolbuyk · 2004-06-28 07:09:15

I bought an old book some time ago (1965 or so) and there they showed a plan of lifting a rocket with a balloon with Helium. It hung in an angle of about 45 degrees. They wrote it had no advantagemants. It still used the same amount of stages when launched from the ground.

C M Edwards · 2005-08-28 14:53:16

This update is coming late. I’ve gotten into a bad habit of just googling and blogging for my news on this topic rather than actual research, and so I didn’t come across this information until it was five months old. JP Aerospace has been relatively quiet about it, but it could pose a major financial problem for them.

According to a series of articles in Aerospace Daily & Defense Report, The US Air Force is planning to renegotiate their contract for JP Aerospace’s Near Space Maneuvering Vehicle (NSMV) on the grounds that it has failed to produce results during testing.

According to the articles (AD&DR 20 Oct 2004, 2 Nov 2004, 5 Nov 2004, and 18 Mar 2005), all USAF testing of the NSMV was handed over to Global Solutions for Science and Learning (GSSL) in 2004, who examined JPA’s ascender prototype. GSSL declared that the prototype could not fly because of propeller problems and other unspecified “engineering oversights.” They delayed testing to upgrade the NSMV and exchange the propeller with one of their own design.

GSSL flew two of its own scientific balloons to test their own propeller design prior to putting it on the NSMV. Both flights suffered mechanical failures and returned no results. GSSL declared the NSMV tests a failure, and the Air Force has followed suit. In March 2005, the Air Force announced that NSMV had not done what they expected it to do, and they were now looking at “an appropriate investment strategy to manage to risk of the project.” I have no data about the current state of JPA’s contract, but their USAF support is no longer unqualified.

If USAF withdraws completely, this could be devastating for JPA. Which would be a shame, because, IMHO, the GSSL testing was inconclusive. The GSSL report, while potentially damning, was based on design analysis only. All equipment failures were of GSSL hardware; no JPA hardware was ever flown during six months of GSSL stewardship. Given that JPA claimed to have already conducted successful tests of its propeller and other ascender prototypes prior to the USAF tests, the question of NSMV’s failure is a matter of JPA’s word against GSSL’s.

GSSL’s position as a competitor for similar USAF contracts does not lend it increased credibility in this instance, but its prior record as a contractor does, and they insist NSMV won't fly. If USAF dumps JPA completely, JPA may find it has only two choices to maintain continued credibility with the rest of its sponsors: release its own test data, or fly a working ascender prototype itself on short order. Either would show up GSSL. Neither is a particularly attractive choice.

John Creighton · 2005-08-28 17:46:58

It is a beautiful concept but a 6 km blimp? That is enormous. I didn't catch the size of it when I first read these posts. What is the chance of it getting punctured. Perhaps it would be strong if made of carbon nanotubes. (lol) (The magic pill.). Actually though that would be interesting because then the ship would be the payload. Carbon is in short supply on the moon and needed for space elevators. The ion engine in space would be useful. The whole concept would be beautiful. Take everything up into space and keep it there. A carbon nanotube canvas could even be fashioned into a space station or a space ship. And you know what? If this works on earth it will work that much better on Venus.

John Creighton · 2005-08-28 18:12:39

This site : http://slashdot.org/article.pl?sid=04/05/25/1949225 says it would deliver mass to orbit at about a dollar per tonne. If true that would so solve the problem of getting the material up into space to build a space elevator.

GCNRevenger · 2005-08-28 20:49:07

What??? Use the hyper-expensive vastly difficult to manufacture CNT balloon material for bulk carbon!? No way!

John Creighton · 2005-08-28 22:05:42

What??? Use the hyper-expensive vastly difficult to manufacture CNT balloon material for bulk carbon!? No way!

We are going to need tons of it to go make a space elevator so if we can't make it cheaply for balloons then we can't make a space elevator economical. End of story. Anyway, the price of carbon nano tubes has come down with the latest process. It will drop further.

GCNRevenger · 2005-08-29 05:32:05

Ummmm no:

1: A space elevator won't weigh that much

2: The tubes for the new CNT sheeting are NOT any cheaper, they are still made the regular $500-a-gram way. The sheeting is just a very novel way to use them, not make them.

SpaceNut · 2005-08-29 06:02:30

Notice further down on photo link at hobbyspace, the ship is moved to space by ion drive after floating to near space altitudes.

C M Edwards · 2005-08-29 07:29:21

JP Aerospace claims that their design process for this airship to orbit thing has been underway since at least 2002, and they've had the physical model for an all-airship ascent for much longer than that. Both John Powell and Al Differ at JPA have stated publicly that no undeveloped materials (e.g., unobtainium or carbon nanotube anything) would be necessary for the project, and all of their anticipated contruction materials had been used in high altitude ballooning for years.

So, no, they were probably not holding out for CNT fabric.

Martian Republic · 2005-08-29 09:48:10

I have read articles on that too of using the balloon idea. You have to have two different groups of balloons to make the system work and a high altitude station they call the Darkstar where those two balloons groups meet. The reason they have to have two balloon groups is that they can't use the lower balloons to get into space and they can't bring the upper balloons into the lower atmosphere because they would be crushed by the dense atmosphere. So you would have the Darkstar station sitting about 100,000 feet or so in the air floating around the North Pole somewhere as the transfer station between those two balloon groups. The lower group of balloons are basically the common verity blimp or some variation of it. But, the upper balloons are a whole lot lighter so they can go higher than ever where the Darkstar Station is. Now the plan is to outfit these balloons with something like ion drive or something similar which can give a steady thrust, but where you would not have to bring a lot of fuel to use it. Ion drive is one of the candidates that fills this requirement. Plan is engage there ion engines going parallel to earth for about one to two weeks and as the balloon pick up ground speed in relationship to the earth, it begins to go higher up until it achieve orbit. The reason that you would have to have your ion in use for one to two weeks is, that how long it would take you to get into space by using this method. Now to come back down, you reverse the process and it would take maybe one week to get back down. Since balloon is taking that long to get into space and to come back down, it wouldn't need a heat shield for reentry. This is basically how it suppose to work and the theory behind it. He still working on the proof of concept along with making it working or getting a working model. But, this is basically what he trying to do in a nutshell.

Larry,

hcm1955 · 2006-04-14 13:16:21

It sound like you still need some type of small chem based rocket to push to orbit. Just enough thrust to over come drag, and carry fuel

Bert

MarsDog · 2006-04-14 14:24:08

It sound like you still need some type of small chem based rocket to push to orbit. Just enough thrust to over come drag, and carry fuel

Could try beamed power.
But then, there is the Sun already, just need to focus the light onto a small cylinder,
using hydrogen as the propellant.

Using beamed microwave for Exhaust of 8 km/sec:
http://monolith.caltech.edu/Papers/ParkinThruster.pdf
http://monolith.caltech.edu/Papers/ParkinLauncher.pdf

aldiffer · 2006-05-11 23:44:57

That's about what I thought they would say. They got a nice opportunity to look at a competing vehicle and declare it unworthy. It would have flown, though. There is nothing surprising in that old news.

I am now the CTO at General Orbital. I've carried my interests in inflatables over to our new company where we are putting our own stamp on things. We are a little busy trying to raise cash right now, so I haven't kept up with what people are saying. I'll try to check in occasionally, though.

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Re: Calling our technical experts - Any chance this thing works?

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