Mechanics of Gravitic Drive

[unknown]

OK, Everybody. There's something that's bothered me for a long time
about David's universe, and that's the gravitic impeller wedge drive
system.

A long-standing constraint on acceleration has been the limits of the
gravity compensator, reducing the acceleration felt by the occupants
of a ship to something that their bodies can handle. What I can't
understand is WHY such a thing would be needed? An impeller wedge
is an area of tightly focused gravity projected ahead of the ship,
arranged "above" and "below" it. This gravitational field draws the
vessel forward, which moves the field forward, ad infinitum.

Here's the rub. Gravitational attraction, whatever the mechanism
for interaction is (and we don't know the answer to that one yet),
operates right through matter. David's model seems to be predicated
on the assumption that the gravitational attraction of the wedge acts
on the hull, but not on anything inside the hull (as in crew), thus
creating the requirement for a compensator. If the gravitational
force were able to reach through the hull, then the contents of the
hull (and the crew) would be subjected to the same acceleration as the
hull - and effectively be in a free-fall state with respect to the
hull itself. If the wedge bands were too close to the hull, or if
they were unbalanced, then you could get some quasi-tidal forces if
you moved about the ship too rapidly, but your body wouldn't feel any
excessive accel as long as you remained at rest. Your maximum accel
would only be limited by the strength of the wedge, at least until you
began to approach relativistic speeds. In fact, the constraining
factor would be your particle and radiation shielding, which would be
a constraint of velocity, not accel.

Anyone else have any thoughts on this? It's a fairly glaring hole in
what is otherwise a pretty well thought-out tech base.

[deowll]

Post by unknown
OK, Everybody. There's something that's bothered me for a long time
about David's universe, and that's the gravitic impeller wedge drive
system.
A long-standing constraint on acceleration has been the limits of the
gravity compensator, reducing the acceleration felt by the occupants
of a ship to something that their bodies can handle. What I can't
understand is WHY such a thing would be needed? An impeller wedge
is an area of tightly focused gravity projected ahead of the ship,
arranged "above" and "below" it. This gravitational field draws the
vessel forward, which moves the field forward, ad infinitum.
Here's the rub. Gravitational attraction, whatever the mechanism
for interaction is (and we don't know the answer to that one yet),
operates right through matter. David's model seems to be predicated
on the assumption that the gravitational attraction of the wedge acts
on the hull, but not on anything inside the hull (as in crew), thus
creating the requirement for a compensator. If the gravitational
force were able to reach through the hull, then the contents of the
hull (and the crew) would be subjected to the same acceleration as the
hull - and effectively be in a free-fall state with respect to the
hull itself. If the wedge bands were too close to the hull, or if
they were unbalanced, then you could get some quasi-tidal forces if
you moved about the ship too rapidly, but your body wouldn't feel any
excessive accel as long as you remained at rest. Your maximum accel
would only be limited by the strength of the wedge, at least until you
began to approach relativistic speeds. In fact, the constraining
factor would be your particle and radiation shielding, which would be
a constraint of velocity, not accel.
Anyone else have any thoughts on this? It's a fairly glaring hole in
what is otherwise a pretty well thought-out tech base.

Magic

[Spinner]

Post by unknown
OK, Everybody. There's something that's bothered me for a long time
about David's universe, and that's the gravitic impeller wedge drive
system.
A long-standing constraint on acceleration has been the limits of the
gravity compensator, reducing the acceleration felt by the occupants
of a ship to something that their bodies can handle. What I can't
understand is WHY such a thing would be needed? An impeller wedge
is an area of tightly focused gravity projected ahead of the ship,
arranged "above" and "below" it. This gravitational field draws the
vessel forward, which moves the field forward, ad infinitum.
Here's the rub. Gravitational attraction, whatever the mechanism
for interaction is (and we don't know the answer to that one yet),
operates right through matter. David's model seems to be predicated
on the assumption that the gravitational attraction of the wedge acts
on the hull, but not on anything inside the hull (as in crew), thus
creating the requirement for a compensator. If the gravitational
force were able to reach through the hull, then the contents of the
hull (and the crew) would be subjected to the same acceleration as the
hull - and effectively be in a free-fall state with respect to the
hull itself. If the wedge bands were too close to the hull, or if
they were unbalanced, then you could get some quasi-tidal forces if
you moved about the ship too rapidly, but your body wouldn't feel any
excessive accel as long as you remained at rest. Your maximum accel
would only be limited by the strength of the wedge, at least until you
began to approach relativistic speeds. In fact, the constraining
factor would be your particle and radiation shielding, which would be
a constraint of velocity, not accel.
Anyone else have any thoughts on this? It's a fairly glaring hole in
what is otherwise a pretty well thought-out tech base.

The drive acts on the nodes attached to the hull. The honorverse is
modeled on the age of sail .. so think of the nodes as masts and the
wedges as sails - which is why you need compensators

--
2+2!=5 even for extremely large values of 2

[r***@gmail.com]

Post by Spinner

OK, Everybody.  There's something that's bothered me for a long time
about David's universe, and that's the gravitic impeller wedge drive
system.
A long-standing constraint on acceleration has been the limits of the
gravity compensator, reducing the acceleration felt by the occupants
of a ship to something that their bodies can handle.   What I can't
understand is WHY such a thing would be needed?    An impeller wedge
is an area of tightly focused gravity projected ahead of the ship,
arranged "above" and "below" it.  This gravitational field draws the
vessel forward, which moves the field forward, ad infinitum.  
Here's the rub.   Gravitational attraction, whatever the mechanism
for interaction is (and we don't know the answer to that one yet),
operates right through matter.   David's model seems to be predicated
on the assumption that the gravitational attraction of the wedge acts
on the hull, but not on anything inside the hull (as in crew), thus
creating the requirement for a compensator.   If the gravitational
force were able to reach through the hull, then the contents of the
hull (and the crew) would be subjected to the same acceleration as the
hull - and effectively be in a free-fall state with respect to the
hull itself.  If the wedge bands were too close to the hull, or if
they were unbalanced, then you could get some quasi-tidal forces if
you moved about the ship too rapidly, but your body wouldn't feel any
excessive accel as long as you remained at rest.   Your maximum accel
would only be limited by the strength of the wedge, at least until you
began to approach relativistic speeds.   In fact, the constraining
factor would be your particle and radiation shielding,  which would be
a constraint of velocity, not accel.
Anyone else have any thoughts on this?  It's a fairly glaring hole in
what is otherwise a pretty well thought-out tech base.  

The drive acts on the nodes attached to the hull. The honorverse is
modeled on the age of sail .. so think of the nodes as masts and the
wedges as sails - which is why you need compensators
--
2+2!=5 even for extremely large values of 2

The acceleration compensators are there to keep the vessel and its
contents accelerating at the same rate. When the acceleration field
is unbalanced, the ship, being rigid, still has has uniform
acceleration, but objects within it accelerate relative to the ship.
For small imbalances that have the field increasing from bow to stern,
the vessel seems to bow (a sailing ship can sag in the middle), as the
bow and stern are 'uphill' relative to the center. When the
acceleration increases from the stern to the bow, the vessel seems to
hog (if a ship lacks sufficient bouyancy at the ends, they will sag)
and the ends seem to be downhill from the center.

The first source of imbalance are tidal effects. The first method to
address this is to have the impeller not act on the ship merely as a
supermassive gravity well in front of it, but to form an Alcubiere-
like metric of a large spacetime curve shaped as if there was a large
mass in front of the vessel and an equally large negative mass
(negative masses repels normal matter) behind the vessel. For small
vessels, the drop in push as you go forward, away from where the
negative mass would be is balanced by the increase in pull as you get
closer to where the normal mass would be. The overall net effect is
that as you get away from the center, there is an increasing gravitic
pull forward and dust seldom accumulates on rear bulkheads. As ships
get longer, the simulated masses have to be further and further away
to keep the tidal effects small. Placing the location of the
simulated masses further away, for the same acceleration, also
requires them to be more massive.

The second source of imbalance comes from how the impeller curves
space. The impeller folds higher order space into the local level
space to affect local curvature. Unfortunately, hyperspace is neither
constant nor predictable, so the simulated masses move and shift in
unpredictable ways. As larger starships need to simulate larger
masses at longer distances, they are less able to quickly reposition
them in response to hyperspace shifts. The purpose of the compensator
is to trim the impeller wedge to keep the simulated masses in balance
with each other to keep every loose object (cargo, furniture,
crewmembers) from being accelerated at several g's towards fixed
objects within the vessel. Extreme imbalances will overmatch the
vessel's structure and either attempt to compress it into a disk, or
draw it into a wire. Really extreme conditions will do both at the
same time, but to opposite ends of the vessel. As the ship deforms,
the center of gravity will shift and previously safe zones will enter
the callous grip of the imbalanced acceleration.

[Quadibloc]

Post by unknown
An impeller wedge
is an area of tightly focused gravity projected ahead of the ship,
arranged "above" and "below" it.  This gravitational field draws the
vessel forward, which moves the field forward, ad infinitum.  
Here's the rub.   Gravitational attraction, whatever the mechanism
for interaction is (and we don't know the answer to that one yet),
operates right through matter.   David's model seems to be predicated
on the assumption that the gravitational attraction of the wedge acts
on the hull, but not on anything inside the hull (as in crew), thus
creating the requirement for a compensator.

I would instead take it that the propulsion system involved is not an
"antigravity" propulsion system in that some reactionless mechanism is
creating a gravitational field pulling on the ship.

Offhand, though, I don't recall the precise distinction between the
impeller wedge on the one hand, and the Warshawskis on the other, the
latter being the analogue of sail, the former giving the armaments of
the ships some of the directional characteristics of the cannon on
wooden sailing ships.

John Savard

[Spinner]

Post by Quadibloc

Post by unknown
An impeller wedge
is an area of tightly focused gravity projected ahead of the ship,
arranged "above" and "below" it.  This gravitational field draws the
vessel forward, which moves the field forward, ad infinitum.  
Here's the rub.   Gravitational attraction, whatever the mechanism
for interaction is (and we don't know the answer to that one yet),
operates right through matter.   David's model seems to be predicated
on the assumption that the gravitational attraction of the wedge acts
on the hull, but not on anything inside the hull (as in crew), thus
creating the requirement for a compensator.

I would instead take it that the propulsion system involved is not an
"antigravity" propulsion system in that some reactionless mechanism is
creating a gravitational field pulling on the ship.
Offhand, though, I don't recall the precise distinction between the
impeller wedge on the one hand, and the Warshawskis on the other, the
latter being the analogue of sail, the former giving the armaments of
the ships some of the directional characteristics of the cannon on
wooden sailing ships.
John Savard

The only thing that makes sense, sorta, is this:
1. The nodes build the sails and wedges and "manage" them
2. Said nodes and sails pull on the ship, but the gravity gradient is
insane because they are so close. Think "Neutron Star" by Larry
Niven.
3. Because the gradient is so high, there are significant tidal
effects, probably in the 100s of G range .. but they are naturally a
percentage of the total accel.
4. Thus, the pull on one deck could be 5000g at the floor and at the
ceiling it could be 5050g (made up numbers) - this would be
uncomfortable (and fatal)
5. Given 4, the compensators simply correct tidal effects within the
ship. The ship is 'falling' into a gravity well at 600g, so the
compensators only handle the internal tidal effect so there is no
reason for the hulls to be made of unobtanium.
6. Same with the missiles - if the tidal change from node to node is
only a few hundred or thousand G - its no problem for standard
containers. (a 'copperhead' artillery shell is full of sensors, and
it's fired from a howitzer.

Basicaly, things are lugged around by artificial black hole gravity
wells .. the compensators simply handle the minor (dozens/hundred)
gravities that naturally come from being so close to a gravity well as
strong as a wedge.

Ta Da

--
2+2!=5 even for extremely large values of 2

[unknown]

Post by Spinner
1. The nodes build the sails and wedges and "manage" them
2. Said nodes and sails pull on the ship, but the gravity gradient is
insane because they are so close. Think "Neutron Star" by Larry
Niven.
3. Because the gradient is so high, there are significant tidal
effects, probably in the 100s of G range .. but they are naturally a
percentage of the total accel.
4. Thus, the pull on one deck could be 5000g at the floor and at the
ceiling it could be 5050g (made up numbers) - this would be
uncomfortable (and fatal)
5. Given 4, the compensators simply correct tidal effects within the
ship. The ship is 'falling' into a gravity well at 600g, so the
compensators only handle the internal tidal effect so there is no
reason for the hulls to be made of unobtanium.
6. Same with the missiles - if the tidal change from node to node is
only a few hundred or thousand G - its no problem for standard
containers. (a 'copperhead' artillery shell is full of sensors, and
it's fired from a howitzer.
Basicaly, things are lugged around by artificial black hole gravity
wells .. the compensators simply handle the minor (dozens/hundred)
gravities that naturally come from being so close to a gravity well as
strong as a wedge.
Ta Da

Yes, but.....

Remember just how large things are in Weber's universe. We tend
to think of things like wedges as sitting quite close to the hull of a
ship, but he's talked about them extending over 300Km from the vessel
generating them. At those kinds of distances, Tidal accelerations
would be minimal, especially as the vessel isn't actually moving or
rotating with respect to the wedge. As long as the two bodies (the
gravity well and the vessel) are motionless with respect to each
other, tidal forces (as such) do not exist. A human being inside the
vessel might be able to generate some minor tidal accelerations by
running VERY rapidly through the vessel, but I doubt that they would
be large enough to measure.

Enough said. This has always bothered me, and I was just curious if
anyone else had considered it.

Michael

[r***@gmail.com]

Post by Spinner
1. The nodes build the sails and wedges and "manage" them
2. Said nodes and sails pull on the ship, but the gravity gradient is
insane because they are so close.  Think "Neutron Star" by Larry
Niven.
3. Because the gradient is so high, there are significant tidal
effects, probably in the 100s of G range .. but they are naturally a
percentage of the total accel.
4. Thus, the pull on one deck could be 5000g at the floor and at the
ceiling it could be 5050g  (made up numbers) - this would be
uncomfortable (and fatal)
5. Given 4, the compensators simply correct tidal effects within the
ship. The ship is 'falling' into a gravity well at 600g, so the
compensators only handle the internal tidal effect so there is no
reason for the hulls to be made of unobtanium.
6. Same with the missiles - if the tidal change from node to node is
only a few hundred or thousand G - its no problem for standard
containers. (a 'copperhead' artillery shell is full of sensors, and
it's fired from a howitzer.
Basicaly, things are lugged around by artificial black hole gravity
wells .. the compensators simply handle the minor (dozens/hundred)
gravities that naturally come from being so close to a gravity well as
strong as a wedge.
Ta Da

Yes, but.....    
     Remember just how large things are in Weber's universe.  We tend
to think of things like wedges as sitting quite close to the hull of a
ship, but he's talked about them extending over 300Km from the vessel
generating them.  At those kinds of distances, Tidal accelerations
would be minimal, especially as the vessel isn't actually moving or
rotating with respect to the wedge.   As long as the two bodies (the
gravity well and the vessel) are motionless with respect to each
other, tidal forces (as such) do not exist.   A human being inside the
vessel might be able to generate some minor tidal accelerations by
running VERY rapidly through the vessel, but I doubt that they would
be large enough to measure.  
Enough said.   This has always bothered me, and I was just curious if
anyone else had considered it.
Michael

Tidal forces are not the result of bodies moving relative to each
other, but because the bodies are not point masses. Each object
within a grav field is at a its own distance from the grav source, so
each object has to calculate its own acceleration. While a ship is
not a point mass, its acceleration is calculated by assuming it was a
point mass located at its center of mass, so each object within the
hull experiences tidal effects as a function from its distance from
the vessel's center of mass. For a source at 300km, it is roughly one
part in every 150,000 for each meter of seperation. While this seems
negligible, for a 600m long vessel running at 500g's, the tidal
effects at each end are 2g's.

If the space curvature from the impeller is equivalent to a normal
mass pulling from the front and a negative mass pushing from behind,
the tidal effects mostly cancel out, so the sources can be much
closer, but slight misalignments of where the simulated sources are
will have severe effects.

[Loren Pechtel]

Post by Spinner
1. The nodes build the sails and wedges and "manage" them
2. Said nodes and sails pull on the ship, but the gravity gradient is
insane because they are so close. Think "Neutron Star" by Larry
Niven.

A better addressing of neutron star tidal forces is Dragon's
Egg/Starquake by Robert L. Forward. He works out the math of putting
a *MANNED* station in a very low orbit around a neutron star--and no
antigravity, either.

Post by Spinner
5. Given 4, the compensators simply correct tidal effects within the
ship. The ship is 'falling' into a gravity well at 600g, so the
compensators only handle the internal tidal effect so there is no
reason for the hulls to be made of unobtanium.

Actually, they are. G forces that would squash the occupants to red
paste leave the hull intact.

[Loren Pechtel]

Post by unknown
Here's the rub. Gravitational attraction, whatever the mechanism
for interaction is (and we don't know the answer to that one yet),
operates right through matter. David's model seems to be predicated
on the assumption that the gravitational attraction of the wedge acts
on the hull, but not on anything inside the hull (as in crew), thus
creating the requirement for a compensator. If the gravitational
force were able to reach through the hull, then the contents of the
hull (and the crew) would be subjected to the same acceleration as the
hull - and effectively be in a free-fall state with respect to the
hull itself. If the wedge bands were too close to the hull, or if
they were unbalanced, then you could get some quasi-tidal forces if
you moved about the ship too rapidly, but your body wouldn't feel any
excessive accel as long as you remained at rest. Your maximum accel
would only be limited by the strength of the wedge, at least until you
began to approach relativistic speeds. In fact, the constraining
factor would be your particle and radiation shielding, which would be
a constraint of velocity, not accel.

Does it act on the hull or does it act on the drive components built
into the hull?

He does have some crazy notions about how strong the hull can be--has
there ever been a ship built that could withstand anything like the 2k
g's one ship pulled? (Unmanned, operating under remote control.)

[michael roegner]

On Mon, 08 Mar 2010 16:22:19 -0800, Loren Pechtel

Post by Loren Pechtel

Post by unknown
a constraint of velocity, not accel.

Does it act on the hull or does it act on the drive components built
into the hull?
He does have some crazy notions about how strong the hull can be--has
there ever been a ship built that could withstand anything like the 2k
g's one ship pulled? (Unmanned, operating under remote control.)

I'd have to be dubious about any practical hull design which could
take the 600+ G's of acceleration that the current generation of
Manticoran vessels are boasting if the structure of the hull actually
had to handle the stresses of accelerating that kind of mass at
those accel rates.

If, as one person suggested, the accelerative force is applied to the
drive nodes, which then "pull" the ship along, then a bit of math
would suggest that they have materials technologies that literally
boggle the mind. I'm not too sure how many nodes a drive ring
actually sports, but they'd have to be made from some truly incredible
materials to handle that kind of stress. And more to the point, the
ship would have to be so heavily reinforced that you probably
wouldn't have room for crew or cargo. I dunno, maybe they
could use Slaver stasis fields to stiffen things up?

Even more difficult is the concept of the newer missiles, some of
which are juicing at up to 90K+ gravities. Clearly, if the body of
the missile has to handle the strain of accel, then these bad boys
are pretty much a solid block of titanium (or equivalent). We know
that they have sophisticated sensor suites, laser warheads, and lots
of electronics onboard as well - are we to believe that those
components can handle 90K gravities of accel? I think not. The ONLY
way that this could work is if the wedge actually pulls on the entire
vessel (or missile) at once, thus obviating the need for the hull to
take the accel forces. And if that's the case - you don't need a
compensator. Q.E.D.

[deowll]

Post by michael roegner
On Mon, 08 Mar 2010 16:22:19 -0800, Loren Pechtel

Post by Loren Pechtel

Post by unknown
a constraint of velocity, not accel.

Does it act on the hull or does it act on the drive components built
into the hull?
He does have some crazy notions about how strong the hull can be--has
there ever been a ship built that could withstand anything like the 2k
g's one ship pulled? (Unmanned, operating under remote control.)

I'd have to be dubious about any practical hull design which could
take the 600+ G's of acceleration that the current generation of
Manticoran vessels are boasting if the structure of the hull actually
had to handle the stresses of accelerating that kind of mass at
those accel rates.
If, as one person suggested, the accelerative force is applied to the
drive nodes, which then "pull" the ship along, then a bit of math
would suggest that they have materials technologies that literally
boggle the mind. I'm not too sure how many nodes a drive ring
actually sports, but they'd have to be made from some truly incredible
materials to handle that kind of stress. And more to the point, the
ship would have to be so heavily reinforced that you probably
wouldn't have room for crew or cargo. I dunno, maybe they
could use Slaver stasis fields to stiffen things up?
Even more difficult is the concept of the newer missiles, some of
which are juicing at up to 90K+ gravities. Clearly, if the body of
the missile has to handle the strain of accel, then these bad boys
are pretty much a solid block of titanium (or equivalent). We know
that they have sophisticated sensor suites, laser warheads, and lots
of electronics onboard as well - are we to believe that those
components can handle 90K gravities of accel? I think not. The ONLY
way that this could work is if the wedge actually pulls on the entire
vessel (or missile) at once, thus obviating the need for the hull to
take the accel forces. And if that's the case - you don't need a
compensator. Q.E.D.

I think it was Asimov that said that any tech sufficiently advanced is going
to look like magic to those less advanced which this would be except it is a
complete fiction having nothing to do with the real world which gets me back
to my original answer: magic. Author waves magic wand and we do a suspension
of disbelief.

[Spinner]

Post by deowll

Post by michael roegner
On Mon, 08 Mar 2010 16:22:19 -0800, Loren Pechtel

Post by Loren Pechtel

Post by unknown
a constraint of velocity, not accel.

Does it act on the hull or does it act on the drive components built
into the hull?
He does have some crazy notions about how strong the hull can be--has
there ever been a ship built that could withstand anything like the 2k
g's one ship pulled? (Unmanned, operating under remote control.)

I'd have to be dubious about any practical hull design which could
take the 600+ G's of acceleration that the current generation of
Manticoran vessels are boasting if the structure of the hull actually
had to handle the stresses of accelerating that kind of mass at
those accel rates.
If, as one person suggested, the accelerative force is applied to the
drive nodes, which then "pull" the ship along, then a bit of math
would suggest that they have materials technologies that literally
boggle the mind. I'm not too sure how many nodes a drive ring
actually sports, but they'd have to be made from some truly incredible
materials to handle that kind of stress. And more to the point, the
ship would have to be so heavily reinforced that you probably
wouldn't have room for crew or cargo. I dunno, maybe they
could use Slaver stasis fields to stiffen things up?
Even more difficult is the concept of the newer missiles, some of
which are juicing at up to 90K+ gravities. Clearly, if the body of
the missile has to handle the strain of accel, then these bad boys
are pretty much a solid block of titanium (or equivalent). We know
that they have sophisticated sensor suites, laser warheads, and lots
of electronics onboard as well - are we to believe that those
components can handle 90K gravities of accel? I think not. The ONLY
way that this could work is if the wedge actually pulls on the entire
vessel (or missile) at once, thus obviating the need for the hull to
take the accel forces. And if that's the case - you don't need a
compensator. Q.E.D.

I think it was Asimov that said that any tech sufficiently advanced is going
to look like magic to those less advanced which this would be except it is a
complete fiction having nothing to do with the real world which gets me back
to my original answer: magic. Author waves magic wand and we do a suspension
of disbelief.

Arthur C. Clarke. Often referred to as Clarke's Law: "Any
sufficiently advance technology is indistinguishable from magic."
--
2+2!=5 even for extremely large values of 2

[Don Sample]

Post by Loren Pechtel

Post by unknown
Here's the rub. Gravitational attraction, whatever the mechanism
for interaction is (and we don't know the answer to that one yet),
operates right through matter. David's model seems to be predicated
on the assumption that the gravitational attraction of the wedge acts
on the hull, but not on anything inside the hull (as in crew), thus
creating the requirement for a compensator. If the gravitational
force were able to reach through the hull, then the contents of the
hull (and the crew) would be subjected to the same acceleration as the
hull - and effectively be in a free-fall state with respect to the
hull itself. If the wedge bands were too close to the hull, or if
they were unbalanced, then you could get some quasi-tidal forces if
you moved about the ship too rapidly, but your body wouldn't feel any
excessive accel as long as you remained at rest. Your maximum accel
would only be limited by the strength of the wedge, at least until you
began to approach relativistic speeds. In fact, the constraining
factor would be your particle and radiation shielding, which would be
a constraint of velocity, not accel.

Does it act on the hull or does it act on the drive components built
into the hull?

It seems to act on the hull, and objects generally within the wedge.
There are multiple comments about how towing pods can slow a ship down,
unless those pods are towed within the wedge.

[michael roegner]

Post by Don Sample
It seems to act on the hull, and objects generally within the wedge.
There are multiple comments about how towing pods can slow a ship down,
unless those pods are towed within the wedge.

If that's the case, then either A) they've come up with a hull
material that blocks gravity waves (but does not
cancel out accelerative forces), or B) there's no need
for a compensator and ships can accelerate just as
hard as they have the power curve to support it.

I can think of several examples in the stories where A is
contraindicated, so I guess that we've just got an
unexplained inconsistency.

[Loren Pechtel]

Post by Don Sample

Post by Loren Pechtel

Post by unknown
Here's the rub. Gravitational attraction, whatever the mechanism
for interaction is (and we don't know the answer to that one yet),
operates right through matter. David's model seems to be predicated
on the assumption that the gravitational attraction of the wedge acts
on the hull, but not on anything inside the hull (as in crew), thus
creating the requirement for a compensator. If the gravitational
force were able to reach through the hull, then the contents of the
hull (and the crew) would be subjected to the same acceleration as the
hull - and effectively be in a free-fall state with respect to the
hull itself. If the wedge bands were too close to the hull, or if
they were unbalanced, then you could get some quasi-tidal forces if
you moved about the ship too rapidly, but your body wouldn't feel any
excessive accel as long as you remained at rest. Your maximum accel
would only be limited by the strength of the wedge, at least until you
began to approach relativistic speeds. In fact, the constraining
factor would be your particle and radiation shielding, which would be
a constraint of velocity, not accel.

Does it act on the hull or does it act on the drive components built
into the hull?

It seems to act on the hull, and objects generally within the wedge.
There are multiple comments about how towing pods can slow a ship down,
unless those pods are towed within the wedge.

I think that's a different matter.

The drive doesn't seem to care about the mass of what's being pulled
inside the wedge but it does care about the mass of anything being
towed outside the wedge.

[r***@gmail.com]

Post by Loren Pechtel

Post by unknown
Here's the rub.   Gravitational attraction, whatever the mechanism
for interaction is (and we don't know the answer to that one yet),
operates right through matter.   David's model seems to be predicated
on the assumption that the gravitational attraction of the wedge acts
on the hull, but not on anything inside the hull (as in crew), thus
creating the requirement for a compensator.   If the gravitational
force were able to reach through the hull, then the contents of the
hull (and the crew) would be subjected to the same acceleration as the
hull - and effectively be in a free-fall state with respect to the
hull itself.  If the wedge bands were too close to the hull, or if
they were unbalanced, then you could get some quasi-tidal forces if
you moved about the ship too rapidly, but your body wouldn't feel any
excessive accel as long as you remained at rest.   Your maximum accel
would only be limited by the strength of the wedge, at least until you
began to approach relativistic speeds.   In fact, the constraining
factor would be your particle and radiation shielding,  which would be
a constraint of velocity, not accel.

Does it act on the hull or does it act on the drive components built
into the hull?
He does have some crazy notions about how strong the hull can be--has
there ever been a ship built that could withstand anything like the 2k
g's one ship pulled?  (Unmanned, operating under remote control.)

The Honorverse canon is inconsistent in that regard. If the materials
really could support those loads, the biggest concern about the
failure of a skydome's foundation is finding the structure after the
wind has finished playing with it. The fact that, in Flag in Exile, a
falling panel of the stuff meant to stay erect in only a planetary
gravity field is heavy enough to kill someone strongly implies that
starship hulls are not actually handling the stresses km per second
squared accelerations.

[Loren Pechtel]

Post by r***@gmail.com

Post by Loren Pechtel
He does have some crazy notions about how strong the hull can be--has
there ever been a ship built that could withstand anything like the 2k
g's one ship pulled?  (Unmanned, operating under remote control.)

The Honorverse canon is inconsistent in that regard. If the materials
really could support those loads, the biggest concern about the
failure of a skydome's foundation is finding the structure after the
wind has finished playing with it. The fact that, in Flag in Exile, a
falling panel of the stuff meant to stay erect in only a planetary
gravity field is heavy enough to kill someone strongly implies that
starship hulls are not actually handling the stresses km per second
squared accelerations.

There is the freighter that was kamikazed by remote control, though.
It *WAS* taking the load. There's also the mention of reducing bodies
to a thin red paste if the compensator fails.

[Spinner]

Post by unknown
OK, Everybody. There's something that's bothered me for a long time
about David's universe, and that's the gravitic impeller wedge drive
system.
A long-standing constraint on acceleration has been the limits of the
gravity compensator, reducing the acceleration felt by the occupants
of a ship to something that their bodies can handle. What I can't
understand is WHY such a thing would be needed? An impeller wedge
is an area of tightly focused gravity projected ahead of the ship,
arranged "above" and "below" it. This gravitational field draws the
vessel forward, which moves the field forward, ad infinitum.
Here's the rub. Gravitational attraction, whatever the mechanism
for interaction is (and we don't know the answer to that one yet),
operates right through matter. David's model seems to be predicated
on the assumption that the gravitational attraction of the wedge acts
on the hull, but not on anything inside the hull (as in crew), thus
creating the requirement for a compensator. If the gravitational
force were able to reach through the hull, then the contents of the
hull (and the crew) would be subjected to the same acceleration as the
hull - and effectively be in a free-fall state with respect to the
hull itself. If the wedge bands were too close to the hull, or if
they were unbalanced, then you could get some quasi-tidal forces if
you moved about the ship too rapidly, but your body wouldn't feel any
excessive accel as long as you remained at rest. Your maximum accel
would only be limited by the strength of the wedge, at least until you
began to approach relativistic speeds. In fact, the constraining
factor would be your particle and radiation shielding, which would be
a constraint of velocity, not accel.
Anyone else have any thoughts on this? It's a fairly glaring hole in
what is otherwise a pretty well thought-out tech base.

This may be a duplicate but...

The only thing that makes sense, sorta, is this:
1. The nodes build the sails and wedges and "manage" them
2. Said nodes and sails pull on the ship, but the gravity gradient is
insane because they are so close. Think "Neutron Star" by Larry
Niven.
3. Because the gradient is so high, there are significant tidal
effects, probably in the 100s of G range .. but they are naturally a
percentage of the total accel.
4. Thus, the pull on one deck could be 5000g at the floor and at the
ceiling it could be 5050g (made up numbers) - this would be
uncomfortable (and fatal)
5. Given 4, the compensators simply correct tidal effects within the
ship. The ship is 'falling' into a gravity well at 600g, so the
compensators only handle the internal tidal effect so there is no
reason for the hulls to be made of unobtanium.
6. Same with the missiles - if the tidal change from node to node is
only a few hundred or thousand G - its no problem for standard
containers. (a 'copperhead' artillery shell is full of sensors, and
it's fired from a howitzer.

Basicaly, things are lugged around by artificial black hole gravity
wells .. the compensators simply handle the minor (dozens/hundred)
gravities that naturally come from being so close to a gravity well as
strong as a wedge.

Ta Da
--
2+2!=5 even for extremely large values of 2