Using lift to increase speeds

wrote:
Orbital speed is where centripetal force equals gravity force and is
given by;

v = sqrt(GMe/r)

Which can be derived from the following three equations;

F = G*m*Me/r^2 - gravitational force
a = v^2/r - centripetal acceleration
F = ma - relating mass and acceleration

a = F/m = GMe/r^2 - gravitational acceleration
a = v^2/r - centripetal acceleration

Setting the two accelerations equal

v^2/r = GMe/r^2
v^2 = GMe/r
v = sqrt(GMe/r)

If we increase velocity by 41.4% we double the centripetal
acceleration, which means that if we were to fly an aircraft at Mach 33
we'd need wings to hold it in the atmosphere! Since wings lift
aircraft all the time against gravity, it seems reasonable to believe
that wings could hold an aircraft down. Everything would seem quite
normal to the occupants, except down would be up to them, and the lift
would be directed toward the Earth's center.

The vehicle if possible would be capable of circumnavigating the Earth
in 60 minutes - and delivering payloads to targets anywhere in 30
minutes or less.

Would such a craft be possible?

Yes. I speculated about this possibility for the use with beamed
propulsion:

From: Robert Clark
Date: Sat, Nov 19 2005 2:23 pm
Email: "Robert Clark"
Groups: sci.astro, sci.physics, sci.math
Subject: Math question for the trajectory of beamed propulsion.
http://groups.google.com/group/sci.a...a00732000ef7f7

This would also be applicable to the scenario where electrical power
for propulsion is transmitted though long cables:

From: Robert Clark
Date: Fri, May 27 2005 12:10 pm
Email: "Robert Clark"
Groups: sci.astro, sci.space.policy, sci.physics,
sci.electronics.design, sci.electronics.misc
Subject: Long cables to power "ioncraft" to orbit?
http://groups.google.com/group/sci.a...2b09463e87dde6

The problem is that though the height to orbit might be 100 km, the
horizontal distance travelled might be 2000 km in order to build up
sufficient speed for orbital velocity.
The proposals for beamed propulsion I've seen though do not use
lifting surfaces for the craft:

Riding Laser Beams to Space.
http://www.space.com/businesstechnol...on_000705.html

However, the lift to drag ratios at hypersonic speeds suggest we might
be able to increase the thrust and therefore the acceleration by
several times if the craft was designed for aerodynamic lift. See the
graph showing lift to drag ratio versus Mach number he

Waverider Design.
http://www.aerospaceweb.org/design/w...averider.shtml

With airplanes you have the thrust directed horizontally to overcome
the drag force against forward motion and the lift provides the force
to keep the airplane aloft. Since subsonic L/D ratios can be 15 to 1
and higher the thrust required from the engines is much less than the
actual weight of the plane.
However, with beamed propulsion a key problem is the dimunition of the
power with distance, which decreases with the square of the distance so
you want to keep the distance short. The idea then in this case using
aerodynamic lift would be to use the thrust produced by the beamed
propulsion to overcome gravity and drag and use the lift force to
provide the higher acceleration to reach orbital velocity in a shorter
distance. Essentially the craft would be pointed upwards so that the
wings/lifting surfaces provide the "lift" in the horizontal direction.
The graph on the "Waverider Design" page shows the L/D ratio can be
about 7 to 8 at hypersonic speeds. For instance if the beamed
propulsion provided a thrust of 1 g to counter gravity plus 4 g's
against drag for a total of 5 g's in the vertical direction, then the
horizontal acceleration could be as much as 8*4 = 32 g's.
Note though it would be important to keep the craft oriented so that
so that the velocity vector is always pointed through the forward
centerline of the craft. When lift and drag calculations are made it's
always in regard to the craft moving so the airstream is flowing more
or less parallel over the wings/lifting surfaces, according to angle of
attack. If instead the airstream was flowing perpindicular to the plane
of the wings the lift would be much less and drag would be much greater
so the L/D ratio would be severely reduced. The aerodynamic control
surfaces would be used to keep the craft properly oriented.
Estimates for beamed propulsion are about 1 megawatt of power to send
1 kilogram to orbit. If say such beamed propulsion provided thrust for
5 g's of acceleration then the lifting force could provide 32 g's, or a
factor of 6 more. So the distance required would be smaller by a factor
6. This means the power required would be smaller by a factor 6^2 = 36.
Then 36 times greater mass could be lifted for the same power. This is
dependent though on how much acceleration beamed propulsion could
provide. If it were 7 g's then the lifting acceleration would be 8*6 =
48 g's, about a factor of 7 more. Then the power required would be less
by 7^2 = 49, and 49 times greater mass could be lifted.
There are apparently megawatt class lasers already in operation:

Mid-Infrared Advanced Chemical Laser (MIRACL).
http://www.fas.org/spp/military/program/asat/miracl.htm

Let's say they are at the 10 megawatt stage now. Then this could
accelerate 10 kilos to orbit. Then with aerodynamic lift it could lift
perhaps 360 kilos to orbit, which is the size of a small sized
satellite.


Bob Clark

I wasn't thinking about space travel. Just air travel.

I was thinking of negative lift as a means for transportation between
points on Earth. The energy usage, and how you power the thing comes
later. But it seems to me if you can have wings to lift an airplane
against the force of gravity, you can also use wings in the atmosphere,
60 km or less altitude, to apply force along with gravity to hold an
airplane to Earth that was travelling at escape velocity.

Its really simple mechanics. Orbital velocity is calculated that way,
set g0 to (a) and solve for V after putting the radius in for the Earth
you have;

a= v2/R so, v = SQRT(g0*Re) = SQRT(9.82*6,366,197) = 7,906.7 m/s

So, if we travelled at the same radius at a speed that would cause
force to be equal to that of gravity aboard the craft, but directed
outward, we'd have to double g0, which taking the square root of 2x the
same number above gives us the square root of 2x the number above or
11,191.8 m/s - which is escape velocity for Earth.

An aircraft that travelled in this way would have an interesting crash
profile in cruise. If the aircraft lost lift during cruise, it would
zip out of the Earth's atmosphere and not be able to return! It would
climb into an escape trajectory! It would likely slow as it rose, but
not much if the altitude of operation were high. It would likely enter
a highly elliptical orbit that had several day period. Entering the
atmosphere again at perigee.

A typical journey would be an interesting one. The aircraft would
accelerate and climb and as it gained speed weight would disappear (but
the acceleration of the aircraft would still be there) and as you moved
through orbital speed (still at low altitude enough to produce
'negative' lift) you'd have to roll over and 'climb' to the Earth as
you accelerated. If you didn't want to do that sort of manuver you'll
have to design wings that can lift down as well as up by a slight
change in angle of attack, or flap setting. But I like the idea of the
roll maneuver. Then you'd cruise until you had to slow down at the end
and repeat the operation in reverse.

It wouldn't be a long cruise. We can figure out what that might be.

Since the circumference of the Earth is 40 million meters by
definition, then to get to the opposite side of the Earth requires
1,788.6 seconds or 29.8 minutes.

Now, if we accelerate at 20.0 m/s/s (a little more than 2 gees) means
it would require 560 seconds to achieve this speed - 9 min 20 sec. To
slow at the other end of the journey at the same rate will require the
same amount of time. Another 9 min and 20 seconds. This is a total of
18 min 40 seconds.

The distance covered is d = 1/2 a * t ^2 so, d = 1/2 * 20.0 * 560^2 =
3,136,000 m at each end. A total distance of 6,272,000 m - leaving
only 13,728,000 m traversed at 11,191.8 m/s which would take 1,226.6
seconds. That's 20.44 minutes.

So, with the acceleration at each end the vehicle would take about
39.11 minutes to get to the other side of the world - saving about 8
minutes of travel time over that of a ballistic flight, and not
exposing the passengers/payload to zero gee! lol.

Since villages and towns are defined psychologically by trip times,
general availability of this sort of transport technology would create
a world wide global village. A step beyond the viritual global village
created by communications technologies like international TV and
telephony of the 1960s.

The energy requirements of such a flight would be equal to that of any
escape maneuver, plus energy suficient to take care of the added drag.
Wave riders - if such can be developed for this speed - may be of some
benefit. But I would suspect that a Cd of 0.14 would be achievable -
whatever you like to call it. High altitudes and low air densities
help. My BOE calculations indicate that propellant sufficient for 1.5x
escape velocity should be adequate.

Some sort of advanced external combustion jet might be possible. If
so, we can dispense with the oxygen that a rocket would need. Jet fuel
burned in a jet engine has performance when expressed in terms of
specific impulse has a specific impulse of 2000 seconds. So, we can
estimate the payload fraction.

Vf = g0 * Isp * LN(1/(1-u)) -- u = 1/EXP(Vf/(g0*Isp)) = 57.5%
propellant

This leaves 42.5% for everything else. If structure fraction is 20%
this leaves 22.5% for payload.

If we take the weights of a Boeing 777-300ER as a reference;

http://www.flug-revue.rotor.com/FRtypen/FR77730e.htm

Weights (Massen)
Operating weight empty (Einsatzleermasse): 167830 kg
Max. payload (max. Nutzlast): 69853 kg
Fuel capacity (Kraftstoff): 181264 litres (47890 gal) equivalent to
145541 kg
Max. zero fuel weight (max. Masse ohne Kraftstoff): 237685 kg
Max. taxi weight (max. Rollmasse): 341100 kg
Max. take-off weight (max. Startmasse): 340195 kg
Max. landing weight (max. Landemasse): 251290 kg

And calculate the fractions;

Max Take Off Weight: 340,195 kg 100%
Fuel Weight 145,541 kg 42.9%
Empty Weight: 167,830 kg 49.3%
Payload w/max fuel 26,824 kg 7.8%

We're doing better than the Boeing 777-300ER- which would be
interesting. If the passengers could take the 2+ gee forces during
take off and landing! lol.

There are three (at least) very favorable assumptions here; we can
maintain 2000 sec Isp equivalent jet operation at escape velocity, we
can maintain a Cd of 0.14 at escape velocities, and we have a
structural fraction of 20% 2/5ths that of the Boeing 777-300ER.

But that should be achievable;

http://darwin.nap.edu/books/0309097150/html/4.html

We can also cheat a little. We can have a reusable booster rocket loft
the aircraft to about 3.6 km/sec and return to the launch center. But
this would require a booster rocket be located at the terminus so that
aircraft could return.

The coolest approach would be for the aircraft to take off after being
fueled with jet-fuel from a conventional runway - and appear anywhere
in 30 minutes or less - which would be awesome!

If the fuel were jet fuel, you'd have about 2x your payload weight in
fuel. A 120 pound person would burn through 20 gallons of gas per
trip! But these ARE rather long trips! lol.

If 40% of the people of a world with 8 billion people had personal
aircraft of this type and used them four times per day, there'd be 3.2
billion aircraft and they'd burn 256 billion gallons of jet fuel per
day! 6 billion barrels per day. About 360x the current usage of all
fuels by the US!

If we sucked carbon out of the air at the same rate we deposited it
we'd maintain CO2 balance, but the processing of that much carbon, even
if balanced would likely pose challenges to the environment.

Another possibliity is beaming energy from space to the aircraft. That
would avoid emissoins altogether. Coordinating 12.8 billion global
flights per day would be an interesting challenge in such a world. But
an advanced global wireless internet combined with advanced GPS and
computing aboard the aircraft, it might be possible to sustain this
sort of traffic.

Even though 3.2 billion aircraft being used 4x per day by a population
of 8 billion people sounds like an ecumenopolis like Coruscant, of Star
Wars fame, you'd be hard pressed to see the traffic outside major
population centers. Actually with easy travel worldwide, population
centers would dissolve over time.

Anyway, even with this high rate of traffic, you'd have about 1
aircraft flash by per hour for every 2 square kilometers of surface
area! The the number of flights (12.8 Gf) times their duration (0.5
hr) and divide by the numbrer of hours per day (24) now difice that
number (0.26 Gf/h) into the surface area of Earth (509,295,000 sq km)
to obtain the number of square kilometers that see an aircraft per hour
(1.95)

Before the production of billions of aircraft, we could have the
production of just a handful. And those could be used to create an
airline of very interesting capabilities. But given that the airlines
aren't doing well these days, and given the commercial failure of the
SST, we might have to wait for jet fuel prices to drop to try that.

But this would would be a cool way to deploy troops very quickly. That
way the US could get rid of all its forward bases and all the problems
with that.

Actually, instead of troops, more interesting would be to have remotely
controlled robots commanded by troops at home, from a spaceborne
communication system. You don't even have to land the aircraft. You
just cruise over the battlefield at escape speed and drop robots that
execute a landing with MEMS based rockets and they start fighting. The
robots would be expendable. So, no resupply or supply chain needs to
be supported. Just plenty of robots at the ready to replace the ones
that are being worn out. Having expendable troops also changes the way
we approach fighting. The robots would be equipped with demolition
charges that would be detonated at the end of their useful life. The
controlling soldiers would be out of harm's way throughout and be able
to command several robots in several different theatres, or different
robots in the same theatre to continue a battle. Also, a team of
soldiers could operate a fighting robot over a 24 hour period, so the
robots would be a continuous fighting presence, even as their
controllers went home, rested, and returned for an 8 or 12 hour
command.

A factory of the type that makes automobiles, could make 5,000,000
remotely controlled robots that received wireless commands (encrpted)
from space at a cost of $30,000 each. 1 million soldiers at US bases
well secured from the fighting, could command 500,000 to 1,500,000
active robots that were pre-placed at locations throughout the world.
These would be supported by 10,000 flights per year of this super
aircraft - 1 per hour - which would require a dozen aircraft with
normal fueling and maintenance. All from a single well secured base in
the US. Each flight deploying 500 robots. A robots life would range
from 45 days to 15 days - depending upon the severity of fighting each
was facing. The troops would command in these battlefields for as long
as the fighting lasted.

That's $200 billion per year to maintain the equivalent of 1,500,000
troops in the field, with 5,000,000 casualties per year - intense
fighting - using only 1,000,000 human commanders.

Combined with our other capabilities, including our nuclear and
intelligence capacities, we could outfight any combination of
conventional forces in the world, without losing soldiers ourselves!

Central to this idea is a handful of a dozen or so aircraft that can
circle the Earth in 80 minutes and deploy 30,000 kg of payload anywhere
along that path.

Another interesting possiblity is to create a 100,000 smaller sized
aircraft, automated, capable of carrying 20,000 kg of payload. This
is along the path toward 3.2 billion personal aircraft. LOL.

This is the equivalent of 100 bags of groceries. In a world of 8
billion people they'd need a bag of groceries twice a week. That means
16 billion bags per week. That's 16 million flights per week. About
100,000 flights per hour. So, since a flight takes about an hour,
you'd need about 200,000 aircraft to provide a delivery service to
every man woman and child on Earth. Go to the USDA website to see how
much of each food type people eat in the US. This would be a first
pass for figuring out the payloads and stuff.

Imagine a single hydroponic facility located in Western Sahara between
Morocco and Mauritania. This unfortunate place has plenty of sun
plenty of sand, about a quarter million people, and lots and lots of
phosphate. With massive desalination of seawater, and approaching the
250,000 people in this place, particularly the rebel guerillas who are
fighting to maintain their land against two very weak rivals. We
could create a huge hydroponic farming facility that took the
phosphate, desalinated water, and 200,000 aircraft of the type
described, along with global space communications, provide a means to
create AND distribute high quality groceries and other small items,
like clothing, toiletries, shoes, etc., to everyone on Earth twice a
week.

The cost of the facility and other infrastructure would be shared by
major retail, farming, and industrial interests. Just as syndicates
are formed to operate oil driling platforms operating in government
leased ocean stretches, supplied by major industrial and eingeering
firms.

Global communications can be used to bring those being supplied into
the global economic infrastructure. Receiving a satellite broadband
connection along with virtual reality gloves and goggles, would allow
folks to apply for employment. MP3 players and VR goggles would allow
folks to engage in educational activities, learning languages, customs
and so forth of others. They would also have entertainment value.

Just as cell phones are given away to promote the selling of telephone
services, so too we can imagine that food and clothing and toiletries
along with the communications hardware could be given away to promote
jobs and consumption as well as political ends, like peace and
prosperity.

Jobs available would be operating guard robots that would be put in
places that had been pacified. Other jobs would be to operate the
robots that tended the hydroponic crops within the vast greenhouses
built over the West Sahara, tending the hardware that made the fresh
water, and all the other stuff that made the magic happen. There would
also be assembly and production jobs making all the material that was
being distributed and all the efforts needed to support the massive
distribution of materials.

Sensors and other hardware could also be carried aboard the 100,000
vehicles in flight. This would allow the identification of folks who
weren't connected, they could be marked, and an introductory package
could be delivered to them, appropriately marked in their own language.


Of course the importance of food and clothing in each person's life
would fall over time as wealth accumulated world wide, and as people
became more sophisticated. There would be a period of housebuilding a
period of acquisition, this is where universal super aircraft would
come into wide use, then a period of searching and personal definition,
a period of integration- similar to the post World War II social
changes in America.

Behind it all would be the hypervelocity aircraft - the element that
tied the world together, just as the automobile tied the US together.

wrote:
I was thinking of negative lift as a means for transportation between
points on Earth. The energy usage, and how you power the thing comes
later. But it seems to me if you can have wings to lift an airplane
against the force of gravity, you can also use wings in the atmosphere,
60 km or less altitude, to apply force along with gravity to hold an
airplane to Earth that was travelling at escape velocity.

Your idea being that you wouldn't need a propulsion system
wasting fuel while this was happening?

The problem is, to get to those speeds requires a lot of fuel, too.

And you'll never eliminate drag.

You'd probably be better off just going above the atmosphere,
orbiting in frictionless space, and falling back to Earth at the
appropriate point.

--Blair

wrote:
wrote:
I was thinking of negative lift as a means for transportation between
points on Earth. The energy usage, and how you power the thing comes
later. But it seems to me if you can have wings to lift an airplane
against the force of gravity, you can also use wings in the atmosphere,
60 km or less altitude, to apply force along with gravity to hold an
airplane to Earth that was travelling at escape velocity.

Your idea being that you wouldn't need a propulsion system
wasting fuel while this was happening?

No I mentioned drag in my discussion.

The problem is, to get to those speeds requires a lot of fuel, too.


Agreed. I estimate you'll need 1.5x the propellant needed to achieve a
straight escape velocity, to execute a single turn around the Earth in
this way - as mentioned in my discussion! lol.

And you'll never eliminate drag.

Of course - which is why I mentioned the cost of drag in my discussion.

You'd probably be better off just going above the atmosphere,
orbiting in frictionless space, and falling back to Earth at the
appropriate point.

Yes, if you didn't mind the altitude and so forth. But if you wanted
to drop troops off or bombs off or bags of groceries off in transit, it
would be nice to stay low.

You're actually ahead of a rocket if you can run a jet efficiently to
make use of the oxygen in the air. So, that's how you pay for the drag
loss so to speak.


--Blair

Read before commenting Blair! lol.

Robert Clark wrote:
wrote:
Orbital speed is where centripetal force equals gravity force and is
given by;

v = sqrt(GMe/r)

Which can be derived from the following three equations;

F = G*m*Me/r^2 - gravitational force
a = v^2/r - centripetal acceleration
F = ma - relating mass and acceleration

a = F/m = GMe/r^2 - gravitational acceleration
a = v^2/r - centripetal acceleration

Setting the two accelerations equal

v^2/r = GMe/r^2
v^2 = GMe/r
v = sqrt(GMe/r)

If we increase velocity by 41.4% we double the centripetal
acceleration, which means that if we were to fly an aircraft at Mach 33
we'd need wings to hold it in the atmosphere! Since wings lift
aircraft all the time against gravity, it seems reasonable to believe
that wings could hold an aircraft down. Everything would seem quite
normal to the occupants, except down would be up to them, and the lift
would be directed toward the Earth's center.

The vehicle if possible would be capable of circumnavigating the Earth
in 60 minutes - and delivering payloads to targets anywhere in 30
minutes or less.

Would such a craft be possible?

Yes. I speculated about this possibility for the use with beamed
propulsion:

From: Robert Clark
Date: Sat, Nov 19 2005 2:23 pm
Email: "Robert Clark"
Groups: sci.astro, sci.physics, sci.math
Subject: Math question for the trajectory of beamed propulsion.
http://groups.google.com/group/sci.a...a00732000ef7f7

This would also be applicable to the scenario where electrical power
for propulsion is transmitted though long cables:

From: Robert Clark
Date: Fri, May 27 2005 12:10 pm
Email: "Robert Clark"
Groups: sci.astro, sci.space.policy, sci.physics,
sci.electronics.design, sci.electronics.misc
Subject: Long cables to power "ioncraft" to orbit?
http://groups.google.com/group/sci.a...2b09463e87dde6

The problem is that though the height to orbit might be 100 km, the
horizontal distance travelled might be 2000 km in order to build up
sufficient speed for orbital velocity.
The proposals for beamed propulsion I've seen though do not use
lifting surfaces for the craft:

Riding Laser Beams to Space.
http://www.space.com/businesstechnol...on_000705.html

However, the lift to drag ratios at hypersonic speeds suggest we might
be able to increase the thrust and therefore the acceleration by
several times if the craft was designed for aerodynamic lift. See the
graph showing lift to drag ratio versus Mach number he

Waverider Design.
http://www.aerospaceweb.org/design/w...averider.shtml

With airplanes you have the thrust directed horizontally to overcome
the drag force against forward motion and the lift provides the force
to keep the airplane aloft. Since subsonic L/D ratios can be 15 to 1
and higher the thrust required from the engines is much less than the
actual weight of the plane.
However, with beamed propulsion a key problem is the dimunition of the
power with distance, which decreases with the square of the distance so
you want to keep the distance short. The idea then in this case using
aerodynamic lift would be to use the thrust produced by the beamed
propulsion to overcome gravity and drag and use the lift force to
provide the higher acceleration to reach orbital velocity in a shorter
distance. Essentially the craft would be pointed upwards so that the
wings/lifting surfaces provide the "lift" in the horizontal direction.
The graph on the "Waverider Design" page shows the L/D ratio can be
about 7 to 8 at hypersonic speeds. For instance if the beamed
propulsion provided a thrust of 1 g to counter gravity plus 4 g's
against drag for a total of 5 g's in the vertical direction, then the
horizontal acceleration could be as much as 8*4 = 32 g's.
Note though it would be important to keep the craft oriented so that
so that the velocity vector is always pointed through the forward
centerline of the craft. When lift and drag calculations are made it's
always in regard to the craft moving so the airstream is flowing more
or less parallel over the wings/lifting surfaces, according to angle of
attack. If instead the airstream was flowing perpindicular to the plane
of the wings the lift would be much less and drag would be much greater
so the L/D ratio would be severely reduced. The aerodynamic control
surfaces would be used to keep the craft properly oriented.
Estimates for beamed propulsion are about 1 megawatt of power to send
1 kilogram to orbit. If say such beamed propulsion provided thrust for
5 g's of acceleration then the lifting force could provide 32 g's, or a
factor of 6 more. So the distance required would be smaller by a factor
6. This means the power required would be smaller by a factor 6^2 = 36.
Then 36 times greater mass could be lifted for the same power. This is
dependent though on how much acceleration beamed propulsion could
provide. If it were 7 g's then the lifting acceleration would be 8*6 =
48 g's, about a factor of 7 more. Then the power required would be less
by 7^2 = 49, and 49 times greater mass could be lifted.
There are apparently megawatt class lasers already in operation:

Mid-Infrared Advanced Chemical Laser (MIRACL).
http://www.fas.org/spp/military/program/asat/miracl.htm

Let's say they are at the 10 megawatt stage now. Then this could
accelerate 10 kilos to orbit. Then with aerodynamic lift it could lift
perhaps 360 kilos to orbit, which is the size of a small sized
satellite.


Bob Clark

What if anything do you know about Usenet contributor ' tomcat '?
-
Brad Guth

Brad Guth wrote:
Robert Clark wrote:
wrote:
Orbital speed is where centripetal force equals gravity force and is
given by;

v = sqrt(GMe/r)

Which can be derived from the following three equations;

F = G*m*Me/r^2 - gravitational force
a = v^2/r - centripetal acceleration
F = ma - relating mass and acceleration

a = F/m = GMe/r^2 - gravitational acceleration
a = v^2/r - centripetal acceleration

Setting the two accelerations equal

v^2/r = GMe/r^2
v^2 = GMe/r
v = sqrt(GMe/r)

If we increase velocity by 41.4% we double the centripetal
acceleration, which means that if we were to fly an aircraft at Mach 33
we'd need wings to hold it in the atmosphere! Since wings lift
aircraft all the time against gravity, it seems reasonable to believe
that wings could hold an aircraft down. Everything would seem quite
normal to the occupants, except down would be up to them, and the lift
would be directed toward the Earth's center.

The vehicle if possible would be capable of circumnavigating the Earth
in 60 minutes - and delivering payloads to targets anywhere in 30
minutes or less.

Would such a craft be possible?

Yes. I speculated about this possibility for the use with beamed
propulsion:

From: Robert Clark
Date: Sat, Nov 19 2005 2:23 pm
Email: "Robert Clark"
Groups: sci.astro, sci.physics, sci.math
Subject: Math question for the trajectory of beamed propulsion.
http://groups.google.com/group/sci.a...a00732000ef7f7

This would also be applicable to the scenario where electrical power
for propulsion is transmitted though long cables:

From: Robert Clark
Date: Fri, May 27 2005 12:10 pm
Email: "Robert Clark"
Groups: sci.astro, sci.space.policy, sci.physics,
sci.electronics.design, sci.electronics.misc
Subject: Long cables to power "ioncraft" to orbit?
http://groups.google.com/group/sci.a...2b09463e87dde6

The problem is that though the height to orbit might be 100 km, the
horizontal distance travelled might be 2000 km in order to build up
sufficient speed for orbital velocity.
The proposals for beamed propulsion I've seen though do not use
lifting surfaces for the craft:

Riding Laser Beams to Space.
http://www.space.com/businesstechnol...on_000705.html

However, the lift to drag ratios at hypersonic speeds suggest we might
be able to increase the thrust and therefore the acceleration by
several times if the craft was designed for aerodynamic lift. See the
graph showing lift to drag ratio versus Mach number he

Waverider Design.
http://www.aerospaceweb.org/design/w...averider.shtml

With airplanes you have the thrust directed horizontally to overcome
the drag force against forward motion and the lift provides the force
to keep the airplane aloft. Since subsonic L/D ratios can be 15 to 1
and higher the thrust required from the engines is much less than the
actual weight of the plane.
However, with beamed propulsion a key problem is the dimunition of the
power with distance, which decreases with the square of the distance so
you want to keep the distance short. The idea then in this case using
aerodynamic lift would be to use the thrust produced by the beamed
propulsion to overcome gravity and drag and use the lift force to
provide the higher acceleration to reach orbital velocity in a shorter
distance. Essentially the craft would be pointed upwards so that the
wings/lifting surfaces provide the "lift" in the horizontal direction.
The graph on the "Waverider Design" page shows the L/D ratio can be
about 7 to 8 at hypersonic speeds. For instance if the beamed
propulsion provided a thrust of 1 g to counter gravity plus 4 g's
against drag for a total of 5 g's in the vertical direction, then the
horizontal acceleration could be as much as 8*4 = 32 g's.
Note though it would be important to keep the craft oriented so that
so that the velocity vector is always pointed through the forward
centerline of the craft. When lift and drag calculations are made it's
always in regard to the craft moving so the airstream is flowing more
or less parallel over the wings/lifting surfaces, according to angle of
attack. If instead the airstream was flowing perpindicular to the plane
of the wings the lift would be much less and drag would be much greater
so the L/D ratio would be severely reduced. The aerodynamic control
surfaces would be used to keep the craft properly oriented.
Estimates for beamed propulsion are about 1 megawatt of power to send
1 kilogram to orbit. If say such beamed propulsion provided thrust for
5 g's of acceleration then the lifting force could provide 32 g's, or a
factor of 6 more. So the distance required would be smaller by a factor
6. This means the power required would be smaller by a factor 6^2 = 36.
Then 36 times greater mass could be lifted for the same power. This is
dependent though on how much acceleration beamed propulsion could
provide. If it were 7 g's then the lifting acceleration would be 8*6 =
48 g's, about a factor of 7 more. Then the power required would be less
by 7^2 = 49, and 49 times greater mass could be lifted.
There are apparently megawatt class lasers already in operation:

Mid-Infrared Advanced Chemical Laser (MIRACL).
http://www.fas.org/spp/military/program/asat/miracl.htm

Let's say they are at the 10 megawatt stage now. Then this could
accelerate 10 kilos to orbit. Then with aerodynamic lift it could lift
perhaps 360 kilos to orbit, which is the size of a small sized
satellite.


Bob Clark

What if anything do you know about Usenet contributor ' tomcat '?
-
Brad Guth




I know quite a bit. What do you need to know?


tomcat

tomcat wrote:
I know quite a bit. What do you need to know?

Excluding everything that's NASA/Apollo; what do you otherwise know
about LL-1 and of the required energy for station-keeping demands
within that interactive zone?

Since SOHO hasn't used a sixth of what they'd expected, and I'd expect
ACE being that mush better yet, therefore how much LL-1 station-keeping
reaction fuel per metric tonne of craft per month (per lunar cycle), or
per 12 lunar cycles are we talking about?
-
Brad Guth

Brad Guth wrote:

tomcat wrote:
I know quite a bit. What do you need to know?

Excluding everything that's NASA/Apollo; what do you otherwise know
about LL-1 and of the required energy for station-keeping demands
within that interactive zone?

Since SOHO hasn't used a sixth of what they'd expected, and I'd expect
ACE being that mush better yet, therefore how much LL-1 station-keeping
reaction fuel per metric tonne of craft per month (per lunar cycle), or
per 12 lunar cycles are we talking about?

Per Brad per what per are per you per yapping per about per now?

--
COOSN-266-06-39716
Official Associate AFA-B Vote Rustler
Official Overseer of Kooks and Saucerheads in alt.astronomy
Official "Usenet psychopath and born-again LLPOF minion",
as designated by Brad Guth

"Who is "David Tholen", Daedalus? Still suffering from
attribution problems?"
-- Dr. David Tholen

Robert Clark,
It must have been GOOGLE/Usenet lunch time again because, I've gotten
back into Usenet after another one of my usual account-full, please
post later messages.

For some reason(s) that seem to continually defy the regular laws of
fly-by-rocket physics, whereas these all-knowing fly-by-rocket wizards
of this mostly Jewish run Republican Usenet that summarily sucks and
blows via NASA's infomercial-science, are still acting as though it's
their one and only truth and nothing but the truth, as having been
insisting that the adding of whatever g forces to their rocket-science
is nothing but representing a good thing, adds measurably to their
hocus-pocus capability of getting whatever payload(s) of tonnage away
from Earth (especially if going for the moon), and otherwise beats the
holy heck out of anything the likes of what "tomcat" or much less that
of whatever I've had to offer that's involving lower amounts of applied
thrust that's offering lesser g forces to overcome, as based upon the
energy usage that involves greater density fuel that burns off at a
sufficient but less aggressive rate from a mostly composite rocket or
spaceplane.

Of course, you can't hardly start yourself off with such an effort if
the 30% inert GLOW has your rocket butt summarily glued to the
launching pad, and then having to fight the added insult to injury of
whatever the extra forces of applied acceleration will unavoidably
contribute as to demanding of extra applied thrust energy that'll tend
to keep yourself or of whatever tonnage from getting nearly as much
away from Earth. The 'tomcat' waverider spaceplane at perhaps
representing a 5% inert GLOW (including payloads) is at least taking us
in the right direction.

I'm fairly certain that our 'tomcat' already knows everything there is
to know about all of this:
Waverider Design
http://www.aerospaceweb.org/design/w...averider.shtml

On Earth, such as utilizing a blimp or balloon craft and of it's
payload demands zero thrust in order to obtain a maximum of perhaps 20
km in altitude.

On Venus that blimp or balloon like craft and of it's payload maximum
altitude is more likely capable of 100+km, of which for the likes of
Venus is nearly LVO (Low Venus Orbit), especially if considering the
65+kg/m3 worth of buoyancy and of the 90.5% gravity factor to start off
with, and if that effort were involving a "waverider" format of a rigid
airship might logically be all the better. Taking further into account
the available solar energy of 2650 w/m2 plus the underside getting an
extra secondary/recoil influx of roughly 75%~80% on top of that,
whereas lo and behold you've got yourself one hell of a nifty renewable
energy resourse that's only going away when and if you elect as to
cruise that rigid airship into the somewhat cooler and obviously dark
nighttime season of Venus.

Though technically doable, I'm not exactly in favor of promoting the
Venusian waverider rigid airship cruising itself extensively above 100
km, whereas instead I'd focus upon the toasty 25 km ~ 35 km zone as
being a whole lot safer and having loads of extra buoyancy to work
with, which seems a whole lot more nighttime/daytime compatible while
still remaining sufficiently cool, and if need be capable of cruising
as great as 55 km by day that's still affording nearly a bar of what's
mostly a CO2 atmospheric pressure and perhaps merely a desert like
300~325 K (27°~52°C) by day that's well illuminated and worthy of an
otherwise bone dry thermal environment that's still relatively
retrograde calm.

Cruising within the nighttime season isn't actually dark, just being
more IR illuminated from all of those surface geothermal considerations
that are the primary issues having contributed to why the Venusian
environment is so humanly hot and nasty, as well as downright lethal if
you're butt naked and/or too dumbfounded to know better.

tomcat; speaking about "Using lift to increase speeds": how the heck
are you comming along with the R&D as related to those 3D CAD drawings
and 3D visulations of depicting those Venusian terrestrial (waveriders
if need be) rigid airships?
-
Brad Guth

Brad Guth wrote:

... Of course, you can't hardly start yourself off with such an effort if
the 30% inert GLOW has your rocket butt summarily glued to the
launching pad, and then having to fight the added insult to injury of
whatever the extra forces of applied acceleration will unavoidably
contribute as to demanding of extra applied thrust energy that'll tend
to keep yourself or of whatever tonnage from getting nearly as much
away from Earth. The 'tomcat' waverider spaceplane at perhaps
representing a 5% inert GLOW (including payloads) is at least taking us
in the right direction.

I'm fairly certain that our 'tomcat' already knows everything there is
to know about all of this:
Waverider Design
http://www.aerospaceweb.org/design/w...averider.shtml

...
-
Brad Guth

I found this after a Google search:

Tomcat's Spaceplane.
http://www.thespacerace.com/forum/in...p?topic=927.90

His proposal isn't worked out in detail, but his basic idea is to use
rocket engines such as the Space Shuttle main engines but with a
lifting body to use aerodynamic lift. This is different from hypersonic
scramjets in that it wouldn't be airbreathing, just using a lifting
body with rocket engines. There was a long discussion on that forum on
its feasibility, or lack thereof.
I was also thinking about this possibility. The idea might be workable
with a slight addendum: when loaded with fuel and oxidizer, the total
weight could be higher than the the actual thrust, the lift being used
to raise the craft to high altitude. The thrust would be used to to
propel the craft forward against drag and lift would be used to raise
it, just as with airplanes. This it would seem would save fuel since
the lift force is greater than the drag.
But what you really want is horizontal, i.e., tangential, velocity to
put a rocket in orbit. So after much of the fuel is burned when the
thrust is now exceeding the weight why not now orient the craft so the
lift force is directed horizontally? Now the thrust is providing
vertical acceleration to overcome the gravity and the drag as with
usual rockets, but the horizontal acceleration is being provided by the
lift force.
The calculation of the trajectory though is made more difficult by the
fact that you are not travelling in a straight-line or in a circle at a
constant speed where the lift is easy to calculate. I'm trying to find
an optimal trajectory that would result in minimal fuel usage to reach
orbital speed.



Bob Clark