A cheap and easy way to space.

Page 7 - Seeking answers about space? Join the Space community: the premier source of space exploration, innovation, and astronomy news, chronicling (and celebrating) humanity's ongoing expansion across the final frontier.
C

csmyth3025

Guest
In order to achieve truly affordable access to space we need - at a minimum - a fully reuseable launch-to-orbit crew vehicle. What comes to mind is an air launched, scaled-down version of the proposed VentureStar - which had a proposed payload capacity of 45,000 lb.

The other thing that comes to mind is the cost of fuel. Taking the prototype x-33 as an example, the fuel specifications are 30,000 lb of liquified hydrogen and 180,000 lbs of LOX. According to Astronautics.com, in 1980 NASA was paying $0.08/kg for LOX and #3.60/kg for liquified hydrogen. The fuel costs for one flight of the x-33 would be about $6550 for LOX and about $49,100 for the liquified hydrogen. I'm thinking that a different (cheaper) fuel would be a better choice. Most liquid-fueled rockets use a highly refined version of kerosene (RP-1). The Russians (among others) have investigated - and used - Liquified Natural Gas.

Liquified hydrogen is attractive because of its high Isp - but it seems that it's darn expensive and darn hard to work with.

Chris
 
A

Astro_Robert

Guest
Halman,

Actually the sewpt wing came into play for transonic and later supersonic flight. For long range, long straight wings and subsonic flight is best. This is why unpowered gliders and the U-2 spy plane feature such wings.

However, as a vehicle with straight wings enters the transonic regime (roughly 0.9M - 1.1M) the wing tips will experience a great deal of stress. And in fact at Mach 1.0 it would be likely that the wingtips of a vehicle with straight wings would lie outside the sonic envelope created by the nose, and probably be ripped off the airplane for that reason. Its been a while, but if I recall correctly wing sweep increases wing performance in the transonic region specifically, relative to straight wings which would suffer more transonic flow effects.

Swing-wing aricraft such as F-14, F111 and B-1 are able to use the forward wing position for good subsonic performance, and then use the swept position for supersonic flight.

Back in the 80s, NASA actually experimented with an airplane with forward swept wings. My recollection was that it proved very agile, but that there were serious concerns about trying to fly it supersonically.

As for your carrier wing, I would wonder how much benefit it would provide if it is subsonic, verses say a Pegasus launch vehicle which is air-dropped (One of the principal benefits of the Pegasus style launch is responsiveness in terms of launch window, rather than any substantial increase in payload fraction). And if a carrier wing were to be supersonic, its development costs would be substantial.
 
H

halman

Guest
Astro_Robert":1djje0p4 said:
Halman,

Actually the sewpt wing came into play for transonic and later supersonic flight. For long range, long straight wings and subsonic flight is best. This is why unpowered gliders and the U-2 spy plane feature such wings.

However, as a vehicle with straight wings enters the transonic regime (roughly 0.9M - 1.1M) the wing tips will experience a great deal of stress. And in fact at Mach 1.0 it would be likely that the wingtips of a vehicle with straight wings would lie outside the sonic envelope created by the nose, and probably be ripped off the airplane for that reason. Its been a while, but if I recall correctly wing sweep increases wing performance in the transonic region specifically, relative to straight wings which would suffer more transonic flow effects.

Swing-wing aricraft such as F-14, F111 and B-1 are able to use the forward wing position for good subsonic performance, and then use the swept position for supersonic flight.

Back in the 80s, NASA actually experimented with an airplane with forward swept wings. My recollection was that it proved very agile, but that there were serious concerns about trying to fly it supersonically.

As for your carrier wing, I would wonder how much benefit it would provide if it is subsonic, verses say a Pegasus launch vehicle which is air-dropped (One of the principal benefits of the Pegasus style launch is responsiveness in terms of launch window, rather than any substantial increase in payload fraction). And if a carrier wing were to be supersonic, its development costs would be substantial.
Forgive me for being obtuse, but I thought that the swept wing design of virtually every commercial airliner was to reduce drag, thus improving fuel economy on long flights. These are not transonic aircraft, the last that I heard. The swing-wing design was to improve landing and take-off characteristics, which suffer when the wing is swept.

Another aspect of the design that I am proposing is that the orbiter start its engines while still attached to the carrier wing, run them up to full power for a few seconds, while the wing adapts a nose-up attitude, and then separate. This avoids the loss of altitude incurred when the launch vehicle is dropped before engine start. Proper design of the carrier wing would allow the orbiter to power up and launch without damaging the carrier wing.
 
C

csmyth3025

Guest
Astro_Robert":2c4bfzcb said:
Halman,

...As for your carrier wing, I would wonder how much benefit it would provide if it is subsonic, verses say a Pegasus launch vehicle which is air-dropped (One of the principal benefits of the Pegasus style launch is responsiveness in terms of launch window, rather than any substantial increase in payload fraction). And if a carrier wing were to be supersonic, its development costs would be substantial.
To say that the development costs of a supersonic carrier wing would be "substantial" is a relative term that should be viewed in the context of other crew launch-to-orbit proposals such as the now-canceled Constellation project, part of which comprised the Aries I/Orion crew-launch system. Wikipedia provides this cost estimate for the development and per-flight cost of the crew-launch system:

Regarding the Orion Crew Exploration Vehicle (CEV):

"...The FY2006 budget request includes $753 million for continuing development of the CEV. As of 2005[update] the total development costs of the CEV are estimated at $15 billion.[19]
Lockheed Martin's contract for the initial "Schedule A" part of the Orion project, awarded on August 31, 2006 and running through 2013, is worth $3.9 billion. Additional development options in the "Schedule B" part of the contract could be worth up to another $3.5 billion.[20]..."

Regarding the Aries I:

"...The total estimated cost to develop the Ares I through 2015 has risen from $28 billion in 2006 to more than $40 billion in 2009.[36]
Originally scheduled for first test flights in 2011, the independent analysis by the Augustine Commission found in late 2009 that due to technical and financial problems Ares I was not likely to have its first crewed launch until 2017-2019 under the current budget, or late 2016 with an unconstrained budget.[37] The Augustine Commission also stated that Ares I and Orion would have an estimated recurring cost of almost $1 billion per flight.[38]..."

For comparison, the development cost of the Concorde is given as "...In December, 1974, a written Parliamentary answer gave the information that the cost to Britain and France of developing Concorde up to the point at which it will enter airline service was then estimated to be £974 million....". The value of the Pound Sterling is given as $2.65 US in March, 1972 (per Wikipedia). This results in a development cost of $2.58 Billion (in 1972 dollars).



Supersonic high-altitude aircraft are not cutting-edge technology. The XB-70 Valkyrie was a mid-to-late 50's design that first flew in 1964. It was capable of sustained Mach 3 speeds and had a service ceiling of 77,000 ft. The Concorde was an early-to-mid 60's design first flown in 1969. It was capable of sustained Mach 2 and had a maximum operating altitude of 60,000 ft. This aircraft racked up 50,000 flights and 2.5 million passengers in 27 years of commercial service (1976-2003). In that time only one aircraft was lost (an accident that was attributed to debris on the runway puncturing a fuel tank during take-off in 2000).

The advantages of air-launch have been listed previously in this thread. Primarily, air-launch significantly reduces the "gravity drag" associated with vertical take-off of the orbiter needed to climb above the denser lower atmosphere. It should be noted that the density of the atmosphere at ~53,000 ft is about 1/10 sea level air pressure. The orbiter itself is thus able to devote more of its fuel to down range velocity - the main delta V component needed to achieve LEO.

So far we've been accustomed to throwing pieces of our launch vehicles overboard as we us them up. This practice doesn't lend itself well to a commercially viable transportation system. I believe that a fully reuseable launch system is needed. It seems to me that a high altitude carrier wing coupled with a scaled-down VentureStar-like orbiter for crew transport is feasible with existing technology and economically viable - especially if demand for crew transport increases due to commercial interest in space activities.

For now it seems we're stuck with ground-launched expendable rockets for launching (unmanned) heavy payloads to LEO. It will take some future technology to alter this equation.

Chris
 
H

halman

Guest
One of the primary reasons that I have been championing this concept of an air-launched orbiter is because the number of launches to rotate crew personnel will greatly exceed the number of launches needed to build space stations, outfit lunar expeditions, and assemble Mars and Near-Earth Orbit exploration vehicles. If some of the first launches of a heavy-lift booster are for sending up the components and fuel for an Orbital Transfer Vehicle, the payloads to follow will be larger than if the booster were required to inject the payloads into their final orbits.

After we get the OTV up there, we start launching space station components to be used as a base for the OTV, then fuel tanks to refuel the OTV, then another OTV, and so on. But each heavy lift launch is going to need several crew launches to support it, and crew launches will continue after the hardware has been inserted into its final orbit.

One of the primary weaknesses of the Constellation program was the small crew capacity it offered. The Orion capsule was originally designed to carry 5 people, if I remember correctly, and weight constraints lowered that to 3. The International Space Station was designed for a minimum of 6 crew, if memory serves, although that requirement has been modified. But the more people we have in space, the more science we can perform, and the faster we can learn.

As I pointed out in another thread, there is about 6 trillion dollars invested in various equity markets around the world right now. If we can attract even one tenth of one percent of that, we will accelerate the development of space exploration technology tremendously. But we are going to have to be able to put people into space in order to convince investors to bet on us, because people are the only way that things get done. Robots are great, once all the variables have been figured out, and a routine, repetitive process established. But we are far from doing that with space manufacturing right now.

What we need is a core of investors who are willing to accept a 15 to 20 year period of no returns, to influence investment by sovereign wealth funds, such as those in China, so that we are able to operate outside of the restraints imposed by politics. The United States space program has never really had a chance to accomplish anything, because the Congress keeps trying to micromanage the program for the benefit of individual states. A corporate approach, with clearly defined goals, would accomplish far more in a short period of time than anything the U. S. government is likely to do.
 
C

csmyth3025

Guest
If a corporate approach isn't do-able, at least a co-operative approach between the US, the ESA, Russia, China, Japan, India and any other entities (publc or private) would be very helpful.

Chris
 
E

EarthlingX

Guest
csmyth3025":1orvj6gm said:
If a corporate approach isn't do-able, at least a co-operative approach between the US, the ESA, Russia, China, Japan, India and any other entities (publc or private) would be very helpful.

Chris
Wikimedia, picture of the day, i don't know why, but i feel it's related :
File:Blind man carrying a paralysed man.jpg


This is a featured picture on Wikimedia Commons (Featured pictures) and is considered one of the finest images.
This is a featured picture on the Turkish language Wikipedia (Seçkin resimler) and is considered one of the finest images.
 
H

halman

Guest
15 billion dollars to develop a capsule and a service module?!? Corporate welfare, not engineering, that is what I would call it.
 
C

csmyth3025

Guest
halman":3m3fngjf said:
15 billion dollars to develop a capsule and a service module?!? Corporate welfare, not engineering, that is what I would call it.
One does have to wonder why upgrading a 35 year old proven design that's already been sucessfully flown more than a dozen times will cost $15 billion. Wikipedia lists the Apollo program costs as follows:

"...The costs associated with the Apollo spacecraft and Saturn rockets amounted to about $83 billion [Apollo spacecraft: $28 billion (Command/Service Module: $17 billion; Lunar Module: $11-billion), Saturn I, Saturn IB, Saturn V launch vehicles: about $46 billion] in 2005 dollars..."

Notice that the cost associated with the command/service module (essentially, the Orion CEV) was $17 billion to design and build it from scratch. Have they thrown out all the design drawings, test and flight data and specifications for the Apollo? If so, then I guess we're saving $2 billion trying to re-invent the wheel.

Chris
 
H

halman

Guest
I also find it fascinating that the per-flight costs of the Ares-I are "almost 1 billion dollars". This is about what a shuttle flight supposedly costs, although I have heard that the 'actual' cost is more like 750 million. So much infrastructure is required for assembling the stack, rolling it out to the pad, prepping it for launch, and, when it is time to launch, paying all of the people who sit at the consoles, verify range information, operate cameras, etcetera. These costs will be practically identical with the Areas-I, even though it has a solid-fueled first stage, because it launches vertically.

Vertical launching is simply more expensive, I believe, because of the inherent dangers involved. Add to that the problems with weather, and vertical launching is not our best option, I think.
 
C

csmyth3025

Guest
Just for general information, I found this item at:
http://www.aerospaceweb.org/question/ae ... 0025.shtml

"...Okay, back to the Shuttle. Maximum q is usually a factor in all space launches, but we will consider the Shuttle for this example. As the Shuttle ascends during launch, it accelerates quickly. The dynamic pressure q is dependent on the square of the speed, so it must be increasing rapidly as well. Like any vehicle, the structure of the Shuttle can only withstand a certain level of dynamic pressure before it suffers damage. We will call this damaging value of q the "critical q." Before the critical q is reached, the engines of the Shuttle are throttled down to about 65%.

However, while the Shuttle climbs in altitude, not only does the velocity increase rapidly, but the air density decreases rapidly. At some point about one minute after launch and at an altitude of about 35,000 ft (10,675 m), conditions are such that the dynamic pressure has reached "maximum q." After this point, the density begins to drop rapidly enough that the Shuttle can be throttled to full power without fear of structural damage, and the dynamic pressure drops to zero by about 2 minutes after launch..."

I was unable to copy and paste the graphic associated with this article, but it indicates that the Shuttle is going about 1,023 mph at max-Q, or about Mach 1.54 at this altitude.

The main point here is that it doesn't make a whole lot of difference whether the carrier wing is going 500 mph or 1,000 mph - it's the altitude that's important to allow the orbiter to use its thrust unhindered by atmospheric drag to increase its down range velocity (and altitude). A heavy lift cargo aircraft such as the C-17 Globemaster III has a service ceiling of 45,000 ft and the Russian AN-225 has a reported service ceiling of 36,000 ft. Both have a cruise speed of about 500 mph. Neither of these planes use exotic materials or powerplants.

Chris
 
C

csmyth3025

Guest
I found an interesting .pdf file here: http://www.reactionengines.co.uk/downlo ... _22-32.pdf

It details a British single-stage-to-orbit spaceplane (SKYLON) that employs a combined air-breathing turbojet/rocket engine called Sabre. The thing that caught my eye is that this vehicle has an ignition weight of 275,000 kg (605,000 lb) and a payload to LEO of 11,620 kg (25,564 lbs). The air-breathing turbojet is designed to function from speeds of 0 (take-off) to Mach 5.5 at an altitude of 26 km (85,320 ft). Beyond that it operates as a pure LOX/LH2 rocket.

An air-launched vehicle of this type might be more suitable than the (canceled) VentureStar concept for crew transport. Although the SKYLON is intended to be ground-launched, I believe the advantages of air-launching a vehicle of this type with a similar payload capacity could significantly reduce the overall weight.

Chris
 
V

vulture4

Guest
Worth funding further development, although an air launched Skylon would have to be a lot smaller than 275 metric tons!
 
N

neutrino78x

Guest
Well I would certainly rather pay the Brits for access to space than the Russians!!! Because, although not fully as free as the USA -- they still have a Queen -- they are far more free than Russia.

And, does Reaction Engines Limited get some funding from Her Majesty's Government? They seem deserving of a loan or grant or something...

--Brian
 
C

csmyth3025

Guest
neutrino78x":126dagbp said:
Well I would certainly rather pay the Brits for access to space than the Russians!!! Because, although not fully as free as the USA -- they still have a Queen -- they are far more free than Russia.

And, does Reaction Engines Limited get some funding from Her Majesty's Government? They seem deserving of a loan or grant or something...

--Brian
According to their website:
"...The Technology Demonstration Programme started in February 2009 and has the objective of validating the key technologies of the SABRE engine. The programme is funded in part by the European Space Agency and in part by private investment..."

They may have funding for other projects (such as the SKYLON), but I haven't had a chance to research it that much yet.

Chris
 
E

EarthlingX

Guest
Some more info from ESA, with videos :
Achievements obtained within the European LAPCAT program

General outline

The baseline mission requirement of LAPCAT is to reduce travelling time of long-distance flights, e.g. Brussels to Sydney, in about 2 to 4 hours. This requires a new flight regime with Mach numbers ranging from 4 to 8. At these high speeds, classical turbo-jet engines need to be replaced by advanced airbreathing propulsion concepts and hence related technologies need to be developed.



LAPCAT-MR1: Left: Conceptual Design of a Dorsal-Type Mach 8 vehicle: blue indicates the passengers’ area, other colours define different fuel tank shapes. Right: Geometrical comparison with the A-380 and An-225. (courtesy ESA)

Last update: 24 June 2009


There is also LAPCAT II :


LAPCAT II overview

LAPCAT II is a logical follow-up of the previous, co-funded EC-project LAPCAT I, whose objective was to reduce the duration of antipodal flights (that is, flights between two diametrically opposite points on the globe) to less than two to four hours. Among the several vehicles studied, only two novel concepts – for Mach five and Mach eight cruise flight – are retained in the new program. The project, co-funded by the European Commission under the theme of air transportation, will last for four years and involves 16 partners representing six European member states.
 
C

csmyth3025

Guest
On the general subject of providing people with access to LEO, I'm not convinced that a single-stage-to-orbit vehicle is the right way to go. If you look at the sketches of the proposed SKYLON, for instance, what you see is essentially a horizontally launched, ground launched rocket. Although the configuration of this vehicle may perform well in supersonic and hypersonic high altitude flight, the size of the wings tells me that it must rely almost entirely on the thrust of its engines to gain altitude through the lower atmosphere. Using thrust to gain altitude in this manner uses a lot of fuel.

I think that ultimately the configuration that will work best is a beefed-up version of White Knight II as a carrier wing married to a spaceplane concept such as SKYLON. One advantage would be that the carrier wing could carry some (if not most) of the weight of the fully loaded orbiter on take-off, thus reducing the weight of the orbiter's landing gear to what is needed for landing the dry weight of the vehicle plus the return payload. Another advantage would be the ability of the orbiter to run its Sabre engines in the lower atmosphere at reduced thrust to supplement the thrust of the engines of the carrier wing, thus reducing the orbiter's fuel consumption and the size of the carrier wing's engines to more realistic values.

Time will tell over the next 10 or 20 years what system works best - but I have a lot of faith that Burt Rutan and Scaled Composites are on the right track. I like the SKYLON concept, but I just don't think that going from the runway to orbit in it will prove economically viable, or even feasible.

Chris
 
H

halman

Guest
Talking about feasibility made me think of the Apollo taking off. Nearly 5 million pounds, going straight up. Arthur C. Clarke described it as "similar to a fully loaded destroyer going straight up." The Saturn V had 5 engines, each producing 1 million pounds of thrust. Those engines had to run for for nearly 3 minutes, without destroying themselves. Then, they were thrown away.

Backtrack to 1938: The U. S. Air Force is requesting designs for a new bomber aircraft, one which can carry 1,000 pounds of bombs 1,000 miles. The Boeing Company submits a design which is radically different from any other, a four engine behemoth which is called the Model 299. Writers in newspapers question the ability of a single man to control this monster, in spite of the electric assist system. The Model 299 wins the competition, and the B-17 was born.

Compare the B-17 to the 747. The B-17 seems tiny. Yet, one man controls this huge aircraft, if the computer isn't flying it. People don't even think twice about boarding one for a flight lasting 14 hours, and covering 5,000 miles.

When we contemplate an aircraft with a wing span of 100 meters, we must remember that the B-17 seemed huge in its day. We must keep in mind that the newest 747 could carry the weight of a fully fueled, fully loaded B-17 (65,000 pounds,) 8,000 miles!

Simply because something has never been done before does not mean that it cannot be done. Just because something works does not mean that it is the best way of accomplishing what it does. Progress occurs because people decide not to wait for perfection.
 
C

csmyth3025

Guest
halman":1xc3xsfh said:
Talking about feasibility made me think of the Apollo taking off. Nearly 5 million pounds, going straight up...

...Simply because something has never been done before does not mean that it cannot be done. Just because something works does not mean that it is the best way of accomplishing what it does. Progress occurs because people decide not to wait for perfection.
I agree with your thinking on this 100%. Reaction Engines Ltd. should most certainly continue their work on SKYLON and their Sabre engine. Scaled Composite should continue their work, as well as SpaceX and the other companies that are contributing their efforts to achieving better access to space. The great thing about commercializing access to space is that there are now a lot of people working towards the same end. Most have different ideas about how best to get to space. Some will succeed and some will fail, but working on more ideas increases the chance that better methods will be found. It's likely that there will be niche markets for a variety of launch-to-orbit schemes, depending on the specific needs of the customer.

The major problem with governmental institutions like NASA is that they have "a" program (like the Space Shuttle) and, since they're the only player on the field, they're not very open to taking new or different ideas seriously. We now have a chance to explore those ideas and, hopefully, to let the launch market decide which ones work best for their needs.

Chris
 
E

EarthlingX

Guest
csmyth3025":1ziehmie said:
The major problem with governmental institutions like NASA is that they have "a" program (like the Space Shuttle) and, since they're the only player on the field, they're not very open to taking new or different ideas seriously. We now have a chance to explore those ideas and, hopefully, to let the launch market decide which ones work best for their needs.
Chris
Market has already made some decisions, as can be seen in percentages taken by carrier/ launcher class.
 
J

js117

Guest
by halman


In my visualization, a launch rail is indispensable, because the stack will weigh in at around 2,500,000 pounds. An undercarriage that could support that amount of weight is going to weigh hundreds of thousands of pounds, which is totally unnecessary. A cradle, which rolls along the launch track, can support the weight of the two vehicles, and act as the driven element in the catapult. This way, the stack is removed somewhat from the powerful magnetic fields of a railgun. The term 'catapult' implies rapid acceleration, which is misleading, I think. What is desired is to be able to accelerate the stack smoothly to a speed where the carrier wing has several tons of positive lift, so that it will fly out of the cradle, which I estimate will be at about 300-350 miles per hour. This insures positive control once the stack is airborne, and avoids the fuel penalty involved in the carrier wing's engines being solely responsible for accelerating the stack from a standing start.

There is a intresting discussion on www.nasaspaceflight.com about maglev captault system.

Maglev Catapult + Scramjet
The link http://forum.nasaspaceflight.com/index. ... ic=20900.0
 
H

halman

Guest
js117,

The discussion your link leads to brings up many of the points that I have tried to address; I am not proposing to accelerate the stack to anywhere near supersonic speeds, just to a high enough speed that the carrier wing will have plenty of lift; the stack sits in a cradle which is supported by wheels, not a magnetic levitation system; the carrier wing allows orbital inclination to be independent of the catapult orientation; because the stack is only being accelerated to about 350 mph, the launch track does not have to be 20 miles long, but I wouldn't be surprised if it was ten miles long, because enough length must be included for an abort from full take-off speed.

That discussion touches on some wonderful concepts, but I am in a hurry. I want something that could be operational in 5 years, if we spend the money on it. The system described in that discussion is a minimum of 20 years out, possibly more. I don't think that we can wait until the necessary advances are made, if we want to be sure that access to space will continue. We have a window of time, which is closing rapidly, in which to accomplish getting ourselves established in space. There simply are not enough young engineers in the world to be able to guide a large-scale industrial revolution in space right now, and the number is dwindling rapidly, as people retire.

I believe that the system that I propose could be the primary method of putting people into space after a short introductory time, and that developing it would allow us to avoid the cost of man-rating any step rockets. It wouldn't hurt to man-rate something like the Falcon 9, but we really don't want to wait around until they can afford to fly often enough to establish the man-rating. The Soyuz is an adequate back up vehicle, if our main destination is going to be the International Space Station, at least for a few years.

Part of the reason that man-rating is so difficult is because during vertical launches, there is so little room for error. Also, large rockets have had a long history of catastrophic failure, many of which would have destroyed any capsule because there was very little warning of a problem. I believe that my proposed system would be tested with an orbiter which has a small, two-or -three man crew compartment which would be robust enough to withstand the vehicle breaking up at velocities of Mach 5 or better, as well as independent re-entry, plus it could be equipped with ejection seats. Once the basic design has been shown to be reliable, the next orbiters to be built would have larger crew compartments which are not designed to separate from the vehicle, and which would carry the full complement of 10 passengers.

At some point in time, we have to accept the risks involved, and believe that we have created a safe enough system so that ejection seats and break-away crew compartments capable of independent re-entry are not required, just as passengers on airliners are not issued parachutes, and they don't sit in ejection seats. We also have to accept that space travel involves velocities and energies so great that failures are likely to be fatal. Nothing could have saved the Columbia astronauts, because they were already in the atmosphere, traveling at hypersonic velocities. The crew of the Challenger might have survived if the crew compartment had been reinforced so much that the payload would be nearly zero. But they were already traveling fast enough that ejection probably would have been deadly.

Most people think of ejection seats as some kind of safety device. They were created primarily so that pilots of supersonic fighter aircraft would have a way of getting out of a shot up plane that was moving too fast to crawl out of. Ejection seats are dangerous, require frequent maintenance, and have a very limited usefulness. A lot of people also believe that the crew compartment should be able to separate from the launch vehicle, or re-enter by itself, so that the maximum possible level of safety could be achieved. That is simply not possible, if the launch vehicle is going to be a realistic size.

We also need to remember that the only fatalities to occur during space flights by NASA have been the result of management decisions regarding whether or not to fly in the face of conditions which were very likely to result in the loss of the vehicle and crew. When the shuttle has been operated within design parameters, it has been a very safe vehicle.
 
H

halman

Guest
js117,

The lifting body has been considered the ideal re-entry vehicle for some time, because it is not a ballistic projectile, but a controlled, maneuverable craft, which can land like an airplane. That is of vast importance, as the dissipation of energy in the last moments of the landing is critical, and difficult to control without using lift of some kind.

Many people were shocked by the breakup of the Columbia, thinking that the fault lay with the lifting body design. That is like saying that a car is unsafe because it has bald tires. That has nothing to do with the design, but with the way that the design is used. If you let holes get punched in the spacecraft prior to re-entry, it is likely that the vehicle will be lost.

Some people oppose the lifting body design because of the increased weight over capsules. Making something expendable is often an excellent way to reduce its weight and cost, but making a primary form of transportation expendable becomes costly. Even with mass production, step rockets will end up costing more than reusable spacecraft. Perhaps most importantly, pilots like to be able to fly, not just sit and wait.


A normal person is someone you haven't gotten to know yet. :)
 
C

csmyth3025

Guest
I've been watching a video interview with Burt Rutan date March 3, 2010 that can be found here:

http://bigthink.com/burtrutan

It's about an hour long. There's a lot of interesting information in this video that gives us some insight into Burt Rutan's thinking. Perhaps the most interesting statement (to me) that he makes is - and I'm paraphrasing here - : "Unless at least 1/2 of the "experts" on the subject of your project think that what your trying to do is impossible, your doing development, not research."

Another comment he makes is on the subject of "space travel". He draws an analogy that the way people envisioned the use of the "personal computer" in the late 70's and early 80's is not even close to what we think of as "personal computing" today. This forum - and the internet broadcast of his interview - a just two small examples of what I think he's talking about.

I think that from now on, when I hear or read about an idea or a "possible future" comment that seems really wild and whacky, I'll be a little less inclined to dismiss it.

Chris
 

ASK THE COMMUNITY

Latest posts