theslim@engin.umich.edu (Eric Michael Slimko) (02/05/91)
In article <1991Feb4.172846.3706@zoo.toronto.edu>, henry@zoo.toronto.edu (Henry Spencer) writes: > .... > > For really tight turns, what you want is a waverider design that can fly > at high hypersonic speeds in an atmosphere. Then you can do a right-angle > turn or even a 180 around any planet with a substantial atmosphere, e.g. > Venus. Aerodynamic forces do a much better job of holding you down during > the turn than gravity. This also lets you use Mars rather than Jupiter > for outer-planets missions, which is nice because Jupiter's Van Allen belts > are a major hassle for Jupiter gravity assists. > -- I've heard about this kind of thing-- it sounds like a neat ideaalthough the aerodynamics of going that fast through an atmosphere would be rough, not to mention the materials the waverider would have to be made out of. Also, you'd better carry along big thrusters for correcting any errors made in the manuever. Anyone in netland doing any research with high velocity waveriders? One of the more interesting waverider missions I've heard of was using Mars for a gravity assist to get out to Pluto. I don't have the velocities handy, but I remember the time figure as being about 4 years to go from Earth to Pluto using that kind of trajectory. --- Eric Slimko theslim@caen.engin.umich.edu
pjs@euclid.jpl.nasa.gov (Peter Scott) (02/06/91)
In article <1991Feb5.154205.29266@engin.umich.edu>, theslim@engin.umich.edu (Eric Michael Slimko) writes: > In article <1991Feb4.172846.3706@zoo.toronto.edu>, henry@zoo.toronto.edu > (Henry Spencer) writes: > > .... > > > > For really tight turns, what you want is a waverider design that can fly > > at high hypersonic speeds in an atmosphere. > > I've heard about this kind of thing-- it sounds like a neat ideaalthough > the aerodynamics of going that fast through an atmosphere would be rough, > not to mention the materials the waverider would have to be made out of. > Also, you'd better carry along big thrusters for correcting any errors > made in the manuever. Anyone in netland doing any research with high > velocity waveriders? Doubt that he's on the net, but Duncan Lunan was big on this when he gave a seminar on the topic here a few years ago. He was with an organization that was planning scale tests, off the coast of Scotland I believe. Wonder what happened to them? -- "Diane, I'm holding in my hand | Peter Scott, NASA/JPL/Caltech a small box of chocolate bunnies" | (pjs@euclid.jpl.nasa.gov)
disprep@lonex.radc.af.mil (Disaster Preparedness) (02/06/91)
In article <1991Feb5.154205.29266@engin.umich.edu> theslim@caen.engin.umich.edu writes: >In article <1991Feb4.172846.3706@zoo.toronto.edu>, henry@zoo.toronto.edu >(Henry Spencer) writes: >> .... >> >> For really tight turns, what you want is a waverider design that can fly >> at high hypersonic speeds in an atmosphere. Then you can do a right-angle >> turn or even a 180 around any planet with a substantial atmosphere, e.g. >> Venus. Aerodynamic forces do a much better job of holding you down during >> the turn than gravity. This also lets you use Mars rather than Jupiter >> for outer-planets missions, which is nice because Jupiter's Van Allen belts >> are a major hassle for Jupiter gravity assists. >> -- > >I've heard about this kind of thing-- it sounds like a neat idea although >the aerodynamics of going that fast through an atmosphere would be rough, >not to mention the materials the waverider would have to be made out of. >Also, you'd better carry along big thrusters for correcting any errors >made in the manuever. Anyone in netland doing any research with high >velocity waveriders? > >One of the more interesting waverider missions I've heard of was using Mars for >a gravity assist to get out to Pluto. I don't have the velocities handy, >but I remember the time figure as being about 4 years to go from Earth to >Pluto using that kind of trajectory. > >--- These are very interesting ideas that, I agree, would allow a probe to change its direction in a hurry. The problem I see is that when the vehicle enters an atmosphere, it loses kinetic energy in favor of thermal energy. The idea of using this aero-assist method would seem to work okay for a solar impact mission, but I don't see how a probe could reach Pluto in four years after losing kinetic energy. Does it kind of bounce off of the Martian atmosphere and gain a whole bunch of kinetic energy somehow (not at all obvious to yours truly)? Or does the probe's proximity to the planet allow for a greater gravitational kick that more than overcomes the loss to heat? Whatever the reason, I'm certain Mr. Spencer can set my misgivings straight. - Andy ******************************************************************************* * Harold G. "Andy" Andrews II, 1Lt, USAF * "Many the man whose punctuality * * andrewsh@lonex.radc.af.mil * serves only to warm his chair." * * Rome Laboratory/IRRE (USAF/AFSC/ESD) * * * Griffiss AFB, NY USA 13441-5700 * -- Leonard somebody or other * * (315) 330-7788 (AVN prfx 587) * (Not an official USAF viewpoint) * *******************************************************************************
henry@zoo.toronto.edu (Henry Spencer) (02/06/91)
In article <1991Feb5.185021.10001@lonex.radc.af.mil> disprep@lonex.radc.af.mil (Disaster Preparedness) writes: > These are very interesting ideas that, I agree, would allow a probe >to change its direction in a hurry. The problem I see is that when the >vehicle enters an atmosphere, it loses kinetic energy in favor of thermal >energy. The idea of using this aero-assist method would seem to work okay >for a solar impact mission, but I don't see how a probe could reach Pluto >in four years after losing kinetic energy... You lose some energy to air drag in the waverider concept. However, you are doing a turn around a *moving* planet, and there is momentum transfer from planet to probe (or vice versa), just like with a gravity-assist maneuver. >... Does it kind of bounce off >of the Martian atmosphere and gain a whole bunch of kinetic energy somehow... Viewed from a distance, either a gravity-assist maneuver or a waverider turn looks very much like bouncing off the planet. Remember, the planet is moving, so bouncing off it can give you a velocity gain or loss, depending on which direction you come in from and the angle of the bounce. The waverider's advantage is that it can give you a much more drastic bounce, because the aerodynamic forces are much stronger than gravity. -- "Maybe we should tell the truth?" | Henry Spencer at U of Toronto Zoology "Surely we aren't that desperate yet." | henry@zoo.toronto.edu utzoo!henry
crad@polari.UUCP (Charles Radley) (02/06/91)
Here is an article from Duncan Lunana. He sent it to several NSS cahpters inlucing us in Ventura. We believ it is public domain and ok to post her and lsewhere:- Waverider by Duncan Lunan From October 17 to 19, The University of Maryland was host to a major event - the First International Hypersonic Waverider Symposium. This represented the rebirth of a concept of major scientific and political importance, long associated with Glasgow University, and something of a triumph for an amateur group which continued to push for the concept's recognition when it had largely been forgotten. The Waverider re-entry vehicle was devised by Prof. Terrence Nonweiler, Professor of Aeronautics and Fluid Mechanics and later Dean of Engineering of Glasgow University. It was intended to be the manned spacecraft in a British space program based on the Blue Streak missile in the 1960's - canceled by the Macmillan government, and largely forgotten thereafter. Its basis is a shape known as the 'caret wing', which generates a plane shock wave, attached to the leading edges, instead of the sonic boom generated by conventional wings at high speeds. The high-pressure area trapped under the Waverider wing generates lift, and the vehicle functions as a very high-performance glider. Waverider was conceived a a space shuttle, and its job is to deliver payloads from space to the surface of a planet with an atmosphere. In the 1970's, discussions at ASTRA (the Association in Scotland to Research into Astronautics) brought out a number of major jobs for the vehicle in the exploration of Mars, Venus, Jupiter and the rest of the outer planets. In the longer term, when we come to practical exploitation of the Solar System's resources, it will have to be on an international basis and with safeguards for the rights of developing nations. Waverider has a major role to play because its low wing-loading allows it a landing 'footprint', descending from space, which literally envelops the Earth, and also allows it a touchdown speed of less than 160 kph. A delivery vehicle which can land anywhere on Earth, on ordinary runways, will be of great political importance. Other ideas from the ASTRA discussions suggested that in the late 21st century transport Waveriders could have a role comparable to that of Containers in the late 20th. In 1981 ASTRA's Waverider study took a practical turn, and by late 1984 Gordon Dick of ASTRA had achieved the first free flights of hand-launched Waveriders. (Gordon Dick is a designer of sails an hang-gliders, now working as a technician at the Glasgow School of Art.) The first rocket launch took place in 1985, witnessed by Dr. Jim Randolph of the Jet Propulsion Laboratory, Pasadena, which is responsible for the Mariner/Viking/Voyager series of space probes. Dr. Randolph is head of the Starprobe project, which is intended to place an instrumented probe within two million miles of the surface of the Sun - described in some quarters as the most important scientific mission of the century. No rocket in existence can achieve that, so it has to be brought about by planetary slingshot - what's termed an 'aerogravity maneuver', in which the probe would fly through the atmosphere of Venus and Mars to redirect its path towards the Sun. In April of this year Dr. Randolph paid his third visit to ASTRA in Scotland, and confirmed that he regards Waverider as the prime candidate for the Starprobe carrier. The setting up of the Waverider conference in October was due in large part to Dr. Randolph's support of the concept, since he first learned of it from ASTRA in 1984. At his urging the University of Maryland undertook computer studies which resolved the major problem with the Waverider design, eliminating turbulence on the upper surface of the wing, thereby confirming work done in Scotland by Gordon Dick. This result was announced at a small Waverider symposium last year, and the effect was dramatic: the Call for Papers for this year's conference has been answered by no fewer than 78 speakers, and the American space agency NASA is now officially co-sponsoring the event. ASTRA will be represented by Duncan Lunan and Gordon Dick, who will unveil the latest version of his Waverider space shuttle design - including a control system which he hopes will be valid for all Waverider applications. Jim Randolph's Starprobe project will not go before the US Senate and Congress for funding until 1994. Meanwhile work in ASTRA continues, with radio-controlled models and wind-tunnel tests, with the future possibility of rocket flights sponsored by NASA; no amateur society has ever pushed a space project so close to official acceptance before, and the October conference was a very big forward step in that direction. (Ed. - This manuscript, written before the conference, was received after the conference was held. We hope to have further news of the conference and Waverider progress in later issues.)
crad@polari.UUCP (Charles Radley) (02/07/91)
Some of the velocity would be lost due to thermal dissipation, +but
most of it would be redi+rected into a new solar orbit with much higher
eccenricity. The trade of+f is increasing the aphelion by reducing
the perihlion. This is done by changing the velocity vector even
though the magnitude does not increase, and will as you said, be
a slightly smaller because of heat loss.
The perhelion can be below the surface of the Sun because the
spacecraft is heading away from the Sun.
The energy of a highly eccentric orbt can be the same as for a near
circular orbit, so conservation of energy is not violated, and there is
no need to invoke relativity !
Well, Henry, how does that sound ?henry@zoo.toronto.edu (Henry Spencer) (02/08/91)
In article <3302@polari.UUCP> crad@polari.UUCP (Charles Radley) writes: >Some of the velocity would be lost due to thermal dissipation, +but >most of it would be redi+rected into a new solar orbit with much higher >eccenricity. The trade of+f is increasing the aphelion by reducing >the perihlion. This is done by changing the velocity vector even >though the magnitude does not increase... > Well, Henry, how does that sound ? Correct as far as it goes, but it doesn't go far enough. If the planet were stationary, this would be a reasonable analysis. You keep the same magnitude of velocity *with respect to the planet*, but since the planet is moving, that can result in either increased or decreased velocity with respect to the Sun. If you bounce a ball off a car moving rapidly towards you, the ball comes back faster than you threw it. -- "Maybe we should tell the truth?" | Henry Spencer at U of Toronto Zoology "Surely we aren't that desperate yet." | henry@zoo.toronto.edu utzoo!henry
Ron.Rapp@p1.f940.n103.z1.fidonet.org (Ron Rapp) (02/09/91)
In a message to All <07 Feb 91 03:00> Eric Michael Slimko wrote: EM> From: theslim@engin.umich.edu (Eric Michael Slimko) EM> Date: Tue, 5 Feb 1991 15:42:05 GMT EM> Organization: University of Michigan EM> Message-ID: <1991Feb5.154205.29266@engin.umich.edu> EM> Newsgroups: sci.space -- Ron Rapp Internet: Ron.Rapp@p1.f940.n103.z1.fidonet.org Compuserve: >internet:Ron.Rapp@p1.f940.n103.z1.fidonet.org --------------------------------------------------------------------------
ahiggins@pequod.cso.uiuc.edu (Andrew Higgins) (02/10/91)
In article <1991Feb5.154205.29266@engin.umich.edu> theslim@caen.engin.umich.edu writes: >> For really tight turns, what you want is a waverider design that can fly >> at high hypersonic speeds in an atmosphere. Then you can do a right-angle >> turn or even a 180 around any planet with a substantial atmosphere, e.g. >> Venus. Aerodynamic forces do a much better job of holding you down during >> the turn than gravity. This also lets you use Mars rather than Jupiter >> for outer-planets missions, which is nice because Jupiter's Van Allen belts >> are a major hassle for Jupiter gravity assists. > >Anyone in netland doing any research with high >velocity waveriders? No, I don't work in this area, but I can provide you with a reference. Armed with the AIAA paper number, you should have no trouble locating this paper in a decent engineering library. "Hypersonic Maneuvering to Provide Planetary Gravity Assist" AIAA 90-0539 A. McRonald and J. Randolph Jet Propulsion Lab. Pasadena, Ca 28th Aerospace Sciences Meeting January 8-11, 1990/Reno, Nevada Abstract: In a previous papaer the authors analyzed aero-maneuvers at Venus and Earth. In this paper they extend the study to Mars, examining the potential of aero-assist maneuvers at Mars for missions to the Sun and to Pluto, using a high lift/drag vehicle such as the waverider to perform an atmospheric "fly-around" of Mars, in order to rotate the plaentocentric velocity vector, thus adding to the rather small rotation due to gravity alone. A fly-around in one direction or the other can place the aphelion or the perihelion of the resulting orbit at the Mars distance, for missions towards the Sun or towards Pluto, respectively. The parameters of such maneuvers are given as a function of Earth launch velocity. It is found to be advantageous in terms of Earth launch velocity to perform two aero- maneuvers, e.g., one at Venus and then one at Mars. Some problems regarding the actual implementation of the aeromaneuvers are discussed. -- Andrew J. Higgins ahiggins@pequod.cso.uiuc.edu