Manoeuvre drive placement...?!

[Redcap]

Sudden thought, prompted by a comment over on the Cartographer's Guild...

Given that manoeuvre drives above a certain level are gravitic in nature, and do not so much produce thrust, as drag the ship where the crew directs, there doesn't seem to be a requirement to stick the drives at the back of the ship, as there would be for a reaction drive that emits exhaust product to generate thrust in a single direction.

With this in mind, is there any point (sic) in always sticking the M-Drive at the back of the ship, instead of, say, the middle?

 

[AnotherDilbert]

There's no reason the thruster plates have to be hooked up to the stern; they could go up front or inside, for that matter. Whatever makes this work builds up a lot of light and heat though, so it's a lot easier to sink them from outside.

SSOM, p4.

Thruster plates (Manoeuvre drives) are not really gravitic:

Thrusters are somewhat more advanced than gravitic propulsion units, but operate in a similar manner. Their development is an outgrowth of the combined effects of both gravitic technologies and nuclear damper technologies. By reacting with both the strong and weak nuclear force, thrusters are able to produce a reactionless thrust which allows a spaceship to move at high speed even beyond the limits of a strong gravitational field.

SSOM, p2.

 

[Brandon C]

That explanation may forbid internal bow mounted M-drives in the ship, but you could still mount them in external structures.

 

[Redcap]

SSOM?

Never mind, figured it out, Starship operators Manual, published by DGP. Thanks, I'll go have a dekko.

 

[Redcap]

OK, how 'Canon' is this, given how much of the DGP material has been effectively redacted from the system?

Could I do what the poster over on CG did, and mount the entire kit and caboodle in the centre of the ship, for example, thus making 100% of the hull of the ship available for, say, access hatches, airlocks, portholes, turrets, and so on, without need to position a thuster plate, venturii, or cone?

 

[whulorigan]

OK, how 'Canon' is this, given how much of the DGP material has been effectively redacted from the system?

Most of the later versions of Traveller (TNE excepted) used this concept from DGP:SSOM, though the reference to Strong and Weak Nuclear Force manipulation seems to have been dropped entirely in favor of a purely gravitic interaction. Later versions, however, have generally noted that Thruster efficiency drops to 1% beyond 1000 diameters from a gravity source (whereas in SSOM they effectively had infinite range).

The plates themselves would seem to require an external mounting, as they will be dumping heat and ionization from them during operation (the "blue glow"), according to SSOM, which also notes that all attempts to damp or attenuate this byproduct of operation have resulted in downgrading the efficiency of the Thruster.

One of the sidebars in SSOM by the "Old Timer" explicitly mentions some young Naval Architect who thought he had the brilliant idea that he could get some extra thrust out of a specific configuration with the drives mounted at the front, and how simulations showed the ship maneuvering and all lit up and glowing from the ionization on the plates as it approached, giving away its position across the entire system.

Could I do what the poster over on CG did, and mount the entire kit and caboodle in the centre of the ship, for example, thus making 100% of the hull of the ship available for, say, access hatches, airlocks, portholes, turrets, and so on, without need to position a thuster plate, venturii, or cone?

Whether or not the "plates" can be positioned independently of the rest of the thruster M-Drive mechanism, or whether they are an inseparable integral part of the drive is unclear.

 

[whulorigan]

Here is another thought:

According to SSOM, thruster plates only give full thrust along a principal vector perpendicular to the plate. They only yield 25% thrust along axes parallel to the plate, and only 10% thrust in the direction that is both perpendicular and diametric to the plate's normal direction of thrust.

If a plate does not have to be mounted to an exterior surface, then why not mount the plate within an internal housing that permits the plate to rotate freely on all axes in order to take full advantage of 100% thrust based on vector orientation?

 

[Redcap]

Most of the later versions of Traveller (TNE excepted) used this concept from DGP:SSOM, though the reference to Strong and Weak Nuclear Force manipulation seems to have been dropped entirely in favor of a purely gravitic interaction. Later versions, however, have generally noted that Thruster efficiency drops to 1% beyond 1000 diameters from a gravity source (whereas in SSOM they effectively had infinite range).

The plates themselves would seem to require an external mounting, as they will be dumping heat and ionization from them during operation (the "blue glow"), according to SSOM, which also notes that all attempts to damp or attenuate this byproduct of operation have resulted in downgrading the efficiency of the Thruster.

One of the sidebars in SSOM by the "Old Timer" explicitly mentions some young Naval Architect who thought he had the brilliant idea that he could get some extra thrust out of a specific configuration with the drives mounted at the front, and how simulations showed the ship maneuvering and all lit up and glowing from the ionization on the plates as it approached, giving away its position across the entire system.



Whether or not the "plates" can be positioned independently of the rest of the thruster M-Drive mechanism, or whether they are an inseparable integral part of the drive is unclear.

Yeah, that's pretty much what I gathered from SSOM and the other CT/MT material as well; I didn't get any of the intervening rules sets et al until MGT, which failed to mention anything that I could find in that regard.

Here is another thought:

According to SSOM, thruster plates only give full thrust along a principal vector perpendicular to the plate. They only yield 25% thrust along an axes parallel to the plate, and only 10% thrust in the direction that is both perpendicular and diametric to the plate's normal direction of thrust.

If a plate does not have to be mounted to an exterior surface, then why not mount the plate within an internal housing that permits the plate to rotate freely on all axes in order to take full advantage of 100% thrust based on vector orientation?

Interesting idea, and one which would require a load of internal volume to be set aside for the purpose, I expect.

I think I'll stick with conventional drive layouts for the moment, until someone comes along with something that can be ruled as canon for the size, configuration, and placement, of M-drives. Stuffs up a ship design idea I had, but that's life.

Cheers for the comments

 

[kilemall]

Strictly IMTU......

Independent of the M-drive itself, I have jump working by opening a portal ahead of the ship, doing so by means of a massive muon-catalzyed fusion pulse, then using the leftover plasma to vent for a raw reaction acceleration and force the ship through the portal ASAP.

Since the portal is acting as an event horizon, time slows down onboard even as the jump itself is instantaneous, therefore the occupants are not crushed by the 1000 G accel. The week onboard happens during the jump, as time 'goes the other way' FTL.

Voila, it's a week onboard, near instant in 'realtime' so no matter created/destroyed issues, all that fuel goes somewhere logical- and ships have big nozzles on the back.

Since my M-drives can be mixed, it's trivial for the low-reaction mass versions to just reuse the same nozzles.

And 1000D limited drives just doesn't work for The Cloud.

 

[flykiller]

is there any point (sic) in always sticking the M-Drive at the back of the ship, instead of, say, the middle?

if you care about yard accessibility (swaps, repairs, full-on overhauls), then engineering components should be near the exterior to minimize hull cuts.

if you care about streamlining then the ship usually will have a fore/aft profile.

if you care about pilot eyes-on visibility, then the bridge should be in the forward direction of travel.

if you care about efficiently contiguous crew space, then that crew space will be between the bridge and engineering.

if you care about passenger and cargo ingress/egress, then this access should be located at the points most convenient to boarding/debarking facilities - typically forward or midsection.

engineering usually will wind up aft or on side-mount pylons of one nature or another.

 

[Redcap]

Strictly IMTU......

Independent of the M-drive itself, I have jump working by opening a portal ahead of the ship, doing so by means of a massive muon-catalzyed fusion pulse, then using the leftover plasma to vent for a raw reaction acceleration and force the ship through the portal ASAP.

Since the portal is acting as an event horizon, time slows down onboard even as the jump itself is instantaneous, therefore the occupants are not crushed by the 1000 G accel.

Voila, it's a week onboard, near instant in 'realtime' so no matter created/destroyed issues, all that fuel goes somewhere logical- and ships have big nozzles on the back.

Since my M-drives can be mixed, it's trivial for the low-reaction mass versions to just reuse the same nozzles.

And 1000D limited drives just doesn't work for The Cloud.

Yeah, we'll, if it were just IMTU, then it'd internal drives, plates at the centre balance axis of the ship, and devil take the Hindmost. Unfortunately, this is for OTU usage, so I have to pay attention to the rules in the book. Which is irritating, but there y'go

 

[Redcap]

you care about yard accessibility (swaps, repairs, full-on overhauls), then engineering components should be near the exterior to minimize hull cuts.

if you care about streamlining then the ship usually will have a fore/aft profile.

if you care about pilot eyes-on visibility, then the bridge should be in the forward direction of travel.

if you care about contiguous crew space, then it will be between the bridge and engineering.

if you care about passenger and cargo ingress/egress, then this access should be located at the points, presumably forward or midsection, where such access will be most convenient to boarding/debarking facilities - typically forward or midsection.

engineering typically will wind up aft or on side-mount pylons of one nature or another.

Not necessarily on all those points, but main one first, the Hull can be so designed that the cargo bay doors just happen to be a straight line to the engineering deck, via an internal bulkhead that's designed to be unbolt ed every so often, thus permitting full and u tethered access to the engineering deck(s). In a small 100-500, say, size ship, this should be eminently possible. The rest tends to follow by inference, but as I just got to work, I'll ha e to leave these points for later!

 

[mike wightman]

CT maneuver drives are fusion rockets, it says so in HG 79 edition, one of the reasons to have separate main and engineering compartments.

I never liked DGP's explanation of how their maneuver drive works.

The MgT route of handwaving gravitic based thrust works well enough but I still prefer the TNE HEPlaR.

IMTU the maneuver drive uses 'gravitics' interacting with the Higgs field to reduce the inertial mass of a ship (bit like null grav modules on grav vehicles) so that the plasma rocket or ion engine used as main thrust can produce 1-6g of thrust. Damage the gravitics and the drive efficiency is reduced considerably.

 

[flykiller]

the Hull can be so designed that the cargo bay doors just happen to be a straight line to the engineering deck, via an internal bulkhead that's designed to be unbolt ed every so often, thus permitting full and u tethered access to the engineering deck(s).

could be done, especially in a grav-control setting. but most dockyards don't like maneuvering high-mass loads in tight spaces, they just want to get it out and onto the dock.

 

[aramis]

OK, how 'Canon' is this, given how much of the DGP material has been effectively redacted from the system?

Could I do what the poster over on CG did, and mount the entire kit and caboodle in the centre of the ship, for example, thus making 100% of the hull of the ship available for, say, access hatches, airlocks, portholes, turrets, and so on, without need to position a thuster plate, venturii, or cone?

Marc recently (september) sent me a "This is all canon and labeled" listing.
DGP was NOT labeled Apocrypha; The bro's keith (Gamelords), Fasa, Traveller Chronicle, and MJD/Comstar/Avenger were...

Marc is prepared to release a DGP CD as soon as RS comes around to an equitable agreement.

 

[AnotherDilbert]

engineering usually will wind up aft or on side-mount pylons of one nature or another.

Hear, hear!

This is the efficient way to design ships. You can use other configurations, but they should cost extra.

Yeah, we'll, if it were just IMTU, then it'd internal drives, plates at the centre balance axis of the ship, and devil take the Hindmost. Unfortunately, this is for OTU usage, so I have to pay attention to the rules in the book. Which is irritating, but there y'go

You can place the thruster plates in the middle of the ship, but you should need extra cooling, costing space and money.

You can place the thruster plates in movable nacelles, but they would have to handle massive forces, costing space and money.

Or you can handwave that away. It's entirely up to you.

 

[mike wightman]

Marc recently (september) sent me a "This is all canon and labeled" listing.
DGP was NOT labeled Apocrypha; The bro's keith (Gamelords), Fasa, Traveller Chronicle, and MJD/Comstar/Avenger were...

Marc is prepared to release a DGP CD as soon as RS comes around to an equitable agreement.

Does that mean 1248 is apocrypha now? The future is not set...?

 

[AnotherDilbert]

CT maneuver drives are fusion rockets, it says so in HG 79 edition, one of the reasons to have separate main and engineering compartments.

More specifically, CT'77-79 uses reaction drives, CT'80- uses reactionless drives.

 

[mike wightman]

CT 80/81 doesn't comment and therefore the previous version continues until MT.

Then come TNE Frank Chadwick is on record as saying reaction drives were the CT intent all along.

I'll stick with reaction drives.

 

[flykiller]

You can use other configurations

well there's also the top and bottom method - this works great for boats allowing full forward pilot visibility while retaining full aft access. might work for a larger boat too, say a cargo handler like the u.s. army's ch-54b cargo helicopter.