Agreed with John here. Why was this posted at all? Given (a) that conventional aircraft engines can get sulfate and other aerosols to altitudes above 20 km, and that (b) both models and basic understanding of stratospheric circulation suggests this is a sufficient altitude.
This list would be more useful if the posts had a higher signal-to-noise ratio. David -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of John Latham Sent: Friday, April 27, 2012 9:09 AM To: [email protected]; [email protected] Subject: RE: [geo] Good popsci article on key SRM facilitator tech Hello Andrew, Not sure if this is the same point as that made by Steve below. Please dont call stratospheric sulphur seeding SRM. The implicit message conveyed by doing so is that there is only one SRM scheme whereas in fact there are several. Sulphur seeding is the best recognised and best supported SRM idea. It can easily handle having a few neighbours. You are of course not the only one who doesnt make this distiction. All Best Wishes, John. John Latham Address: P.O. Box 3000,MMM,NCAR,Boulder,CO 80307-3000 Email: [email protected] or [email protected] Tel: (US-Work) 303-497-8182 or (US-Home) 303-444-2429 or (US-Cell) 303-882-0724 or (UK) 01928-730-002 http://www.mmm.ucar.edu/people/latham ________________________________________ From: [email protected] [[email protected]] on behalf of Stephen Salter [[email protected]] Sent: Friday, April 27, 2012 3:40 PM To: [email protected] Subject: Re: [geo] Good popsci article on key SRM facilitator tech Andrew May I suggest the insertion of the word 'stratospheric' before SRM in your last email. Stephen Emeritus Professor of Engineering Design Institute for Energy Systems School of Engineering Mayfield Road University of Edinburgh EH9 3JL Scotland Tel +44 131 650 5704 Mobile 07795 203 195 www.see.ed.ac.uk/~shs On 27/04/2012 15:27, Andrew Lockley wrote: > > Mech eng fans will be interested in this great article on high > altitude engines, which have potential for application to the heavy, > high altitude lift needed for SRM. > > Please view online to access rich media. > > http://www.bbc.co.uk/news/science-environment-17864782 > > A > > More from Jonathan Follow Jonathan on Twitter > > Key tests for Skylonspaceplane project > > COMMENTS (215) > > The pre-cooler demonstration is a major step in proving the Skylon > concept > > UK engineers have begun critical tests on a new engine technology > designed to lift a spaceplane into orbit. > > The proposed Skylon vehicle would operate like an airliner, taking off > and landing at a conventional runway. > > Its major innovation is the Sabre engine, which can breathe air like a > jet at lower speeds but switch to a rocket mode in the high atmosphere. > > Reaction Engines Limited (REL) believes the test campaign will prove > the readiness of Sabre's key elements. > > This being so, the firm would then approach investors to raise the > £250m needed to take the project into the final design phase. > > "We intend to go to the Farnborough International Air Show in July > with a clear message," explained REL managing director Alan Bond. > > "The message is that Britain has the next step beyond the jet engine; > that we can reduce the world to four hours - the maximum time it would > take to go anywhere. And that it also gives us aircraft that can go > into space, replacing all the expendable rockets we use today." > > To have a chance of delivering this message, REL's engineers will need > a flawless performance in the experiments now being run on a rig at > their headquarters in Culham, Oxfordshire. > > The test stand will not validate the full Sabre propulsion system, but > simply its enabling technology - a special type of pre-cooler heat > exchanger. > > Sabre is part jet engine, part rocket engine. It burns hydrogen and > oxygen to provide thrust - but in the lower atmosphere this oxygen is > taken from the atmosphere. > > The approach should save weight and allow Skylon to go straight to > orbit without the need for the multiple propellant stages seen in > today's throw-away rockets. > > But it is a challenging prospect. At high speeds, the Sabre engines > must cope with 1,000-degree gases entering their intakes. These need > to be cooled prior to being compressed and burnt with the hydrogen. > > Reaction Engines' breakthrough is a module containing arrays of > extremely fine piping that can extract the heat and plunge the intake > gases to minus 140C in just 1/100th of a second. > > Ordinarily, the moisture in the air would be expected to freeze out > rapidly, covering the pre-cooler's pipes in a blanket of frost and > compromising their operation. > > But the REL team has also devised a means to stop this happening, > permitting Sabre to run in jet mode for as long as is needed before > making the transition to a booster rocket. > > Sabre engine: How the test will work > > Groundbreaking pre-cooler > > 1. Pre-cooler During flight air enters the pre-cooler. In 1/100th of a > second a network of fine piping inside the pre-cooler drops the air's > temperature by well over 100C. Very cold helium in the piping makes > this possible. > > On the test rig, a pre-cooler module of the size that would eventually > go into a Sabre has been placed in front of a Viper jet engine. > > The purpose of the 1960s-vintage power unit is simply to suck air > through the module and demonstrate the function of the heat exchanger > and its anti-frost mechanism. > > Helium is pumped at high pressure through the module's nickel-alloy > piping. > > The helium enters the system at about minus 170C. The ambient air > drawn over the pipes by the action of the jet should as a consequence > dip rapidly to around minus 140C. > > Sensors will determine that this is indeed the case. > > The helium, which by then will have risen to about minus 15C, is > pushed through a liquid nitrogen "boiler" to bring it back down to its > run temperature, before looping back into the pre-cooler. > > "It is important to state that the geometry of the pre-cooler is not a > model. That is a piece of real Sabre engine," said Mr Bond. > > "We don't have to go away and develop the real thing when we've done > these tests; this is the real article." > > The manufacturing process for the pre-cooler technology is already > proven, but investors will be looking to see that the module has a > stable operation and can meet the promised performance. > > The BBC was given exclusive access to film the rig in action. > > Because REL is working on a busy science park, it has to meet certain > environmental standards. > > This means the Viper's exhaust goes into a silencer where the noise is > damped by means of water spray. > > The exhaust gases are at several hundred degrees, and so the water is > instantly vaporised, producing huge clouds of steam. > > Anyone standing outside during a run gets very wet because the vapour > rains straight back down to the ground. > > Future direction > > The REL project has generated a lot of excitement. One reason for that > is the independent technical audit completed last year. > > The UK Space Agency engaged propulsion experts at the European Space > Agency (Esa) to run the rule over the company's engine design. > > Esa's team, which spent several months at Culham, found no obvious > showstoppers. > > "Engineering is never simple. There are always things in the future > that need to be resolved - problems crop up and you have to solve > them," said Dr Mark Ford, Esa's head of propulsion engineering. > > "The issue is, 'do we see anything fundamental from stopping this > engine from being developed?', and the answer is 'no' at this stage. > > "The main recommendation we made is that we would like next to see a > sub-scale engine - so, a smaller version than the final engine - being > tested. > > "So far we've looked at critical component technologies. The next step > is to put those technologies together, build an engine and see it working. > > "We want a demonstration of the thermodynamic cycle. We'd also like to > see the engine operating in air-breathing and rocket mode, and the > transition between the two." > > This sub-scale engine is one of the activities proposed for the next > phase of the project. > > Also included is a series of flight test vehicles that would > demonstrate the configuration of the engine nacelles - the air intakes. > > Additionally, updated design drawings would be produced for the Sabre > engine and the Skylon vehicle. > > So far, 85% of the funding for Reaction Engines' endeavours has come > from private investors, but the company may need some specific > government support if it is to raise all of the £250m needed to > initiate every next-phase activity. > > "What we have learned is that a little bit of government money goes a > long way," said Mr Bond. > > "It gives people confidence that what we're doing is meaningful and > real - that it's not science fiction. So, government money is a very > powerful tool to lever private investment." > > This public seed fund approach to space has certainly found favour > recently within government. > > Ministers put more than £40m into developing the communications > payload for the first satellite operated by the Avanti broadband > company, and they are giving more than £20m to SSTL to make a > prototype radar satellite. > > -- > You received this message because you are subscribed to the Google > Groups "geoengineering" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
