Such a tower has never been built in the history of mankind, and is not likely to be built in the near future, without compelling evidence for its necessity. The above mentioned website does not present this compelling evidence for the necessity of such an engineering effort.
On page 002, the website considers a payload of 530 kg, but here on page 003, the payload is now considered to be as high as 80 tons, not including the mass of the overcarriage nor the counterweight. There has not been presented a believable method by which the initial capacity of the facility can be expanded to its presumably final capacity. With regard to the system's hypothetical feasibility, it is immediately apparent that the cost of developing such a growth path would be a major impediment to any such feasibility.
As illustrated, it most certainly is not a re-entry vehicle.
It is inconceivable to think that 60kW of power can effectively rotate a structure of 400km in diameter. It is not discussed in any of the articles so far, how the envisioned structural mass and launch mass gets from sea level to 150 km altitude.
Power is delivered to the counterweights by ground based high powered solid state lasers. Solar panels made of Aluminum Gallium Arsenide photovoltaic cells receive the energy from the lasers.This is not believable. Earlier in the thread, the author has rejected out of hand any discussion of costs as being pertinent to the idea of feasibility. Here is a new power transmission scheme which has not been considered sufficiently.
The tower is from 100-150 km high and supports an estimated 3,100 tons of passenger elevators, cargo elevators, research station, rotating truss and ribbons.This launch scheme is completely infeasible.
The following are a few excerpts from the backup PDF's used to support the contentions. Joseph A. Carroll (Carroll, J.A.,1986). Carroll suggested that a rotating sling on the surface of an airless body such as the moon might accelerate 10-20 kg payloads to orbital velocity. This is an application in a low gravity vacuum, proposing to send very small payloads into orbit. Part of this idea was intended as an alternative to a linear mass driver. The concept of a mass driver is for "dumb" masses to be fired in the general direction of an orbital catching device, with the expectation that the masses will then be processed by an unspecified mechanism. Perhaps the masses are propellant, perhaps they are ore for refining. Here, there is a thread called "Sling me to (or from) the Moon" which addresses some of these concepts.
As illustrated the overcarriage is not a re-entry vehicle, and cannot return to the launch site, because it is too delicate to survive the forces of re-entry. In addition, unmanned flyback for a 20 ton vehicle from the altitude envisioned, 150 or so km, has not been demonstrated at all, which would necessitate the development costs of proving this concept. It is an unfeasible concept in its entirety.
This is an example of taking the facts of an ultimate strength and modulus of elasticity of a single material and simple geometry, and incorrectly applying these values to the vastly more complex materials and geometry of the 80 ton craft being envisioned. This paper goes on to discuss the four frangible nuts necessary for holding the LV to the launch structure until the proper speed has been obtained. This is an example of improper attention to detail. The entire scheme is unrealistic; that the bolt strength is calculated to the extent that it is, does not bolster the feasibility of the entire scheme.
The air bearings are intended to provide a lifting force to support the launch loads, presumably. However, at the intended launch altitude, air resistance is thought to be virtually negligible. It is not clear to me how these devices are thought to work.
As illustrated, there are no "conventional" aspects to the fuselage design.
An assumption without justification.
This is an inadequate foundation analysis.
Why, from a financial perspective, is your system a better bet than laser/microwave launch or super guns or space fountains/launch loops?
It is like comparing unicorns to fairies, dragons and leprechauns.
Jerry, I'm afraid I'm not qualified to offer an opinion on the engineering of your concept, all I can say is that you do need to recognize that even if there are no, zero, zip, technical obstacles to the construction of a STLS, it still has to make sense in financial terms, there have been a lot of alternatives to current methods used to get to orbit proposed, many of which could work in technical terms, all have so far failed to get finance.Why, from a financial perspective, is your system a better bet than laser/microwave launch or super guns or space fountains/launch loops?
Quote from: Andrew_W on 12/23/2011 07:36 pmWhy, from a financial perspective, is your system a better bet than laser/microwave launch or super guns or space fountains/launch loops?Why compare it to three concepts that are also not proven?It is like comparing unicorns to fairies, dragons and leprechauns.
building 747's would not have been viable in 1950,
I agree that some economic analysis is needed upfront. The economics are one of the biggest selling points of this system. You need to look at costs and revenue. Revenue from aviation may be considerably higher than space launch. The 10km tower has been analyzed in peer reviewed studies and found to be feasible.
I'm pretty sure that unicorns, fairies, dragons and leprechauns are somewhere out past oogie boogie science and not appropriate to this forum.
Quote from: JFSuch a tower has never been built...It is not likely to be built in the near future...
Such a tower has never been built...
It has an aerodynamic shell to protect the structure during reentry, body flaps for attitude control in the atmosphere, reaction control system for attitude control in space, prime power and avionics, landing gear, and a parafoil for landing.
It is inconceivable to think that 60kW of power can effectively rotate a structure of 400km in diameter.
Four 5 MW superconducting electric motors rotate this structure. The superconducting motors already exist as prototypes to 50 MW superconducting electric motors built for nuclear powered aircraft carriers (see the reference material accompanying the concept paper).
Here is a new power transmission scheme which has not been considered sufficiently.
Lawrence Livermore National Laboratory has done lethality testing and modeling using a high-power solid-state laser ...
This launch scheme is completely infeasible.
On the contrary, nothing you've said above backs up this claim. The only thing your comments show is that you've tried to disprove my concept by skimming the introductory remarks covering each subsystem and you didn't even get to the tower. Without reading the detailed technical information in the concept papers, you can not give a true technical evaluation of this concept.
This was fun. Lets do it again sometime but pick a subsystem and lets debate it.
I agree that some economic analysis is needed upfront. The economics are one of the biggest selling points of this system. You need to look at costs and revenue.
Thread will be pulled if it doesn't improve.
Put your considerable talents to some other use.
I include a scan of your tower concept drawn to scale, with the tower located somewhere in the center of Florida. You have not specified a location for this system, so I did. It would be infeasible to clear the real estate in Florida to implement the tower/ribbon system. Perhaps it would be more feasible to consider an island somewhere, but even so, there would have to be negotiated significant changes in global airspace, to allow clearance for such a continually operating system. Without doing any further calculations, the scale of the enterprise is too large to be realistic.
The power needs of the launcher are for useful power, not destructive power. An intermittently fired tactical weapon is not suited for the constant use needed for the rotating device.
I most certainly did get to the tower. Referring to my sketch below, it is clear that the slenderness ratio of the tower is too high to seriously merit further consideration. For purposes of casual analysis, a tower of 3100 mt divided by 150 km, is about 20 kg per meter. There is no way that such a lightweight tower with the functionality required included in the mass estimate can be built. However, it is possible to calculate in great detail, various statistics about such a tower. The calculation does not demonstrate feasibility.
The online description is incomplete.
Quote from: Chris Bergin on 12/23/2011 07:33 pmThread will be pulled if it doesn't improve.It is unlikely that there should be such a hoped for improvement.
This is a tower under tension.
QuoteThis is a tower under tension.Where does the tension come from when most of the tower is outside the atmosphere?
Why compare it to three concepts that are also not proven?It is like comparing unicorns to fairies, dragons and leprechauns.
I have a 30o arc to fire the solid-state laser. It is not continuous. Although, it will fire longer than it takes to bring down a ballistic missile with the Airborne Laser Lab. Some R&D in cooling the laser will be required. But not impossible.
Quote from: JohnFornaro on 12/24/2011 02:25 pmPut your considerable talents to some other use. I'm retired. This gives me the chance to dream and to pursue a dream. Thanks for the compliment.Quote from: JohnFornaroI include a scan of your tower concept drawn to scale, with the tower located somewhere in the center of Florida. You have not specified a location for this system, so I did. It would be infeasible to clear the real estate in Florida to implement the tower/ribbon system. Perhaps it would be more feasible to consider an island somewhere, but even so, there would have to be negotiated significant changes in global airspace, to allow clearance for such a continually operating system. Without doing any further calculations, the scale of the enterprise is too large to be realistic. The scale is daunting. But not impossible. I would prefer continental US for the large volume of traffic I expect but, there is an island in the south pacific near the equator that would be perfect for the STLS, a tropical paradise. It is US territory and has been up for sale for awhile. There are a few islands nearby, so I would have to negotiate airspace issues.
The tower itself would be 15 kilometers (9.3 miles) tall, 230 meters (754 feet) across, and weigh approximately 800,000 tons, or about twice the weight of the world's largest supertanker when fully inflated with a variety of gasses, including helium.
(a) find and develop a technology that both solves a problem on Earth now and can be scaled to solve a problem in space later – a product/service that customers will demand,(b) make lots of money doing this, and finally(c) invest a portion of profits from the established terrestrial ventures for the R&D to solve the space problem when the time is right and demand exists.
The calculation does not demonstrate feasibility.