Leaving Orbit (A contradiction of canon rules)

[Ishmael]

it dependes on what you mean by 'control surfaces'.
pressure/suction slats use no 'control surfaces' yet can be very effective. If I recall properly, the rf-5a vigilante used a system of such for control.

Also, it the speeds that most ships move through atmospheres during GG skimming, just about any fin-like control surface would have to be insanely strong ( massive structure or materials ) keep from being broken off. IMTU, a ship can only turn as many G's in a dogfight as its structure is rated for. and while smaller ships might be able to handle hi stresses without extensive internal structure, large ship's cannot..aka c-5a galaxy's don't barrel-roll or do loops too well.

imtu, the type 's' IS a lifting body
take a looksee at the traveller-oolite yahoo group to see a model of one.

 

[boomslang]

Originally posted by Matthew Bailey:
This is actually wrong. A spaceship may launch from a planet and leave orbit with just a fraction of a G in thrust.

It will take it a long while to get airborn, and then a long while to get up enough velocity to exit the atmosphere, and then more time accellerating to leave orbit...

As has been pointed out, this presumes enough atmo to actually provide lift as well as streamlining that actually takes advantage of it.

But the bigger problem is: how does such a ship end up on the surface of such a world anyway? Either there was enough atmo to let it fly down (probably scortching the hull; note that typically, 2G+ Traveller spacecraft do not need to make high-speed, high-temperature entry interfaces -- they slow down and enter atmo at subsonic velocities if possible), or it must've been built planetside. If it was built locally, that means local Starport B or better, and that means a highport is present, and that's where it's smarter to build it.

So if it landed without cratering, it can take off OK. "If".

 

[boomslang]

Originally posted by Matthew Bailey:
This is actually wrong. A spaceship may launch from a planet and leave orbit with just a fraction of a G in thrust.

It will take it a long while to get airborn, and then a long while to get up enough velocity to exit the atmosphere, and then more time accellerating to leave orbit...

As has been pointed out, this presumes enough atmo to actually provide lift as well as streamlining that actually takes advantage of it.

But the bigger problem is: how does such a ship end up on the surface of such a world anyway? Either there was enough atmo to let it fly down (probably scortching the hull; note that typically, 2G+ Traveller spacecraft do not need to make high-speed, high-temperature entry interfaces -- they slow down and enter atmo at subsonic velocities if possible), or it must've been built planetside. If it was built locally, that means local Starport B or better, and that means a highport is present, and that's where it's smarter to build it.

So if it landed without cratering, it can take off OK. "If".

 

[Judas Iscariot]

Yes, it does assume enough atmosphere and streamlining.

I would think that was a given, but just in case... My Point assumes that the planet in question has a dense enough atmosphere and streamlining, which contrary to some people's opinions, DOES include atmosphic control surfaces (whatever they might be)

 

[Judas Iscariot]

Yes, it does assume enough atmosphere and streamlining.

I would think that was a given, but just in case... My Point assumes that the planet in question has a dense enough atmosphere and streamlining, which contrary to some people's opinions, DOES include atmosphic control surfaces (whatever they might be)

 

[far-trader]

Here's a thought that keeps bouncing around in my head but I keep forgetting to post it, partly because posting of late has become a pita

What about TUG-Boats?

You know, any heavy-gee world could be considered in a manner similar to a port with sandbars, currents, or other such impediments to safe navigation to the dock that TUG-Boats are available to assist ships with 1G drives between orbit and the down port.

I'm thinking the Modular cutter with a 30ton tractor beam module might be neat. Multiple TUG-Boats for larger craft, probably need at least two for even a 200ton ship. I haven't worked out the stats yet but I'm going to over the next little bit during my brief downtimes

Ya hear me, the idea is mine. MINE, MINE, MINE... Look for it later today... presuming I can get past these blasted EXlocks

 

[far-trader]

Here's a thought that keeps bouncing around in my head but I keep forgetting to post it, partly because posting of late has become a pita

What about TUG-Boats?

You know, any heavy-gee world could be considered in a manner similar to a port with sandbars, currents, or other such impediments to safe navigation to the dock that TUG-Boats are available to assist ships with 1G drives between orbit and the down port.

I'm thinking the Modular cutter with a 30ton tractor beam module might be neat. Multiple TUG-Boats for larger craft, probably need at least two for even a 200ton ship. I haven't worked out the stats yet but I'm going to over the next little bit during my brief downtimes

Ya hear me, the idea is mine. MINE, MINE, MINE... Look for it later today... presuming I can get past these blasted EXlocks

 

[mbrinkhues]

Not sure about B2/B5 but in MT and above you could simply use Contra-Gravity Lifters to compensate for the ships weight (not mass) and then slowly thrust away. Since the neutral buyoance is already there all your thrust goes to lifting the beast.

 

[mbrinkhues]

Not sure about B2/B5 but in MT and above you could simply use Contra-Gravity Lifters to compensate for the ships weight (not mass) and then slowly thrust away. Since the neutral buyoance is already there all your thrust goes to lifting the beast.

 

[boomslang]

Originally posted by far-trader:
thinking the Modular cutter with a 30ton tractor beam module might be neat. Multiple TUG-Boats for larger craft, probably need at least two for even a 200ton ship. I haven't worked out the stats yet but I'm going to over the next little bit during my brief downtimes

Ya hear me, the idea is mine. MINE, MINE, MINE... Look for it later today... presuming I can get past these blasted EXlocks

Well, tractor beams specifically are kind of a high-TL option, especially for a world that's rinky-dink Starport D-.

You could perhaps use a couple of empty-cargo-module Cutters (along with Pinnaces, the second-best thrust-to-mass ratio of the standard small craft when scaled up to externally-slung loads; proper Shuttles are first) and a very, very strong towline material, but if small craft -- specifically Cutters -- are available, why isn't surface-to-orbit shuttle service?

 

[boomslang]

Originally posted by far-trader:
thinking the Modular cutter with a 30ton tractor beam module might be neat. Multiple TUG-Boats for larger craft, probably need at least two for even a 200ton ship. I haven't worked out the stats yet but I'm going to over the next little bit during my brief downtimes

Ya hear me, the idea is mine. MINE, MINE, MINE... Look for it later today... presuming I can get past these blasted EXlocks

Well, tractor beams specifically are kind of a high-TL option, especially for a world that's rinky-dink Starport D-.

You could perhaps use a couple of empty-cargo-module Cutters (along with Pinnaces, the second-best thrust-to-mass ratio of the standard small craft when scaled up to externally-slung loads; proper Shuttles are first) and a very, very strong towline material, but if small craft -- specifically Cutters -- are available, why isn't surface-to-orbit shuttle service?

 

[pendragonman]

Ok, not tractor beam. Going with the more traditional view of tugs, magnetic tow cables ala "Empire Strikes Back".

 

[pendragonman]

Ok, not tractor beam. Going with the more traditional view of tugs, magnetic tow cables ala "Empire Strikes Back".

 

[Supplement Four]

Originally posted by far-trader:
What about TUG-Boats?

S4 digs it. Thumbs up.

 

[Supplement Four]

Originally posted by far-trader:
What about TUG-Boats?

S4 digs it. Thumbs up.

 

[Supplement Four]

The IISS Ship Files has a 300 ton Freight Hauler. It picks up cargo containers in space and transports them. No reason why a similar design couldn't work as a tug.

OK, here's an idea you don't see in Trav often: What about a Jump Tug? It could be like the Jump Ship in Sup 10. A subsidized merchant loads up to the gills with speculative trade. Then, pays a J-3 Jump Tug to jump the ship three jumps farther than it could normally go in one hop.

I wonder if the economics of this would work out? Maybe the Jump Tugs cost 1000Cr per vessel displacement ton?

Hmm...

 

[Supplement Four]

The IISS Ship Files has a 300 ton Freight Hauler. It picks up cargo containers in space and transports them. No reason why a similar design couldn't work as a tug.

OK, here's an idea you don't see in Trav often: What about a Jump Tug? It could be like the Jump Ship in Sup 10. A subsidized merchant loads up to the gills with speculative trade. Then, pays a J-3 Jump Tug to jump the ship three jumps farther than it could normally go in one hop.

I wonder if the economics of this would work out? Maybe the Jump Tugs cost 1000Cr per vessel displacement ton?

Hmm...

 

[far-trader]

Yes, the MT version of Tractor "beam" won't work. It's too big, too expensive, too power hungry, and too powerful for our purpose. I have also never been much of a believer in the stats for it. As an outgrowth of gravitics it is imo over sized, over priced, over powered, and under rated.

Repulsors are closer to an extrapolation (again imo) of gravitics turned into a directed force. So it is with that in mind that I interpolated what is, and Chucky is on the mark here, more a "force" tow cable.

Calling it a Tractor Beam fits. The sole purpose of the device is to allow the Cutter to make a "fast line" to the object to tow, without the whole mess of using physical attachments.

I'm throwing a copy of this up in The Fleet forum as well, please direct design specific questions regarding it there (TUG-Boat Cutter Module (CT design)) .

-------

30ton TUG-Boat module for 50ton Modular Cutter

The TUG (Towed Under Gravitics) module is a widely used and versatile addition to any starport's Modular Cutter fleet. With a few of these modules available the Cutters can greatly expand their roles in port operations.

Built at TL15(1) the modules are easily shipped to even low tech backwater ports for use and can be inexpensively return shipped for maintenance or service.

The core of the module is a 25ton gravitic tractor/repulsor(2) with an onboard 2.5ton dedicated fusion power supply and fuel for 4 weeks of operations(3).

By approaching a free body(4) and engaging the TUG module when in close proximity the Cutter is made fast with the free body without putting undue stress on either body or making actual physical contact.

Once the Cutter, or Cutters, are connected in this fashion to the free body the total maneuver capability is calculated as for a single body. This allows the Cutter or Cutters to assist in the lift or descent of underpowered craft or even unpowered loads.

A typical employment of this arrangement is in aiding 1G ships in landing and taking off from worlds with more than 1G surface gravity, typically by employing 2 or more TUG-Boats to assist.

Total cost is MCr10 after standard design discounts.

(1) - Based on fudging the TL14 50ton repulsor bay with a USP of 3, cost of MCr6 and power requirement of 5EP.

Stats are: TL15, USP 1 repulsor/tractor, 25dtons, MCr3.0, -2.5EP

(2) - Because imo both technologies are the same.

(3) - Halving the requirement of 5EP.

(4) - To lift a body the TUG module must be able to separate it from it's environment. Generally any body not attached firmly to another is treated as a free body for this purpose.

 

[far-trader]

Yes, the MT version of Tractor "beam" won't work. It's too big, too expensive, too power hungry, and too powerful for our purpose. I have also never been much of a believer in the stats for it. As an outgrowth of gravitics it is imo over sized, over priced, over powered, and under rated.

Repulsors are closer to an extrapolation (again imo) of gravitics turned into a directed force. So it is with that in mind that I interpolated what is, and Chucky is on the mark here, more a "force" tow cable.

Calling it a Tractor Beam fits. The sole purpose of the device is to allow the Cutter to make a "fast line" to the object to tow, without the whole mess of using physical attachments.

I'm throwing a copy of this up in The Fleet forum as well, please direct design specific questions regarding it there (TUG-Boat Cutter Module (CT design)) .

-------

30ton TUG-Boat module for 50ton Modular Cutter

The TUG (Towed Under Gravitics) module is a widely used and versatile addition to any starport's Modular Cutter fleet. With a few of these modules available the Cutters can greatly expand their roles in port operations.

Built at TL15(1) the modules are easily shipped to even low tech backwater ports for use and can be inexpensively return shipped for maintenance or service.

The core of the module is a 25ton gravitic tractor/repulsor(2) with an onboard 2.5ton dedicated fusion power supply and fuel for 4 weeks of operations(3).

By approaching a free body(4) and engaging the TUG module when in close proximity the Cutter is made fast with the free body without putting undue stress on either body or making actual physical contact.

Once the Cutter, or Cutters, are connected in this fashion to the free body the total maneuver capability is calculated as for a single body. This allows the Cutter or Cutters to assist in the lift or descent of underpowered craft or even unpowered loads.

A typical employment of this arrangement is in aiding 1G ships in landing and taking off from worlds with more than 1G surface gravity, typically by employing 2 or more TUG-Boats to assist.

Total cost is MCr10 after standard design discounts.

(1) - Based on fudging the TL14 50ton repulsor bay with a USP of 3, cost of MCr6 and power requirement of 5EP.

Stats are: TL15, USP 1 repulsor/tractor, 25dtons, MCr3.0, -2.5EP

(2) - Because imo both technologies are the same.

(3) - Halving the requirement of 5EP.

(4) - To lift a body the TUG module must be able to separate it from it's environment. Generally any body not attached firmly to another is treated as a free body for this purpose.

 

[Judas Iscariot]

Aside from the fact that a ship would probably not need a tug, It is a good idea, as it would probably be cheaper to use the tug than to spend all of the fuel needed to break free on your own...

Would depend upon the G of the world and the ship in question...

Tow cables are no problem... We already have cables that are strong enough to tow junk to orbit... We just have nothing that is capable of doing the towing yet... Plenty of stuff to tow.. No tug... Pity...