Aging ships

[BP]

... Forcing spaceship to have the armor rating of a tank doesn't seem right to me because the space shuttle and station aren't plated with 40AV worth of armor are they?
just an idea

OK - was waiting for someone to compare Traveller tech with today’s …

I’ll just list a few key points starting with the Space Shuttle and ISS

#1 Aside from liftoff and re-entry burn (ignoring minor corrections and gravity well), they don’t 'actively' accelerate – and no where near 6G continuous
#2 They actively avoid problems - they are in ‘known space’ with a whole infrastructure of planet-wide, orbital surveillance (including solar flare watch) not to mention historical data.. For example – the ISS is in an orbit high enough to avoid known meteor showers (and of course radiation belts) – it wasn’t placed there by accident and it couldn't survive many other orbits
#3 They do have protection – The ISS has hundreds of shields to protect astronauts and equipment including heavy impact blankets made with Kevlar (like bullet-proof vests, hence my RW analogy above) and a special fabric (ceramic I believe) – and the windows are very thick (multiple pressure and debris panes and not glass) and have metal shutters (I saw a Russian one that irises) and I believe can also be covered with the impact blankets…
The Earth and near Earth environment also provides protection from solar winds, radiation, etc.
#4 Even with all these considered - radiation and to a lesser extent micrometeorites are not insignificant in determining the rated life spans of space equipment. The ISS only had a design life of 15 years – 2015 I think… (not that most space hardware doesn’t last long past their designed lifetimes). And the space shuttles I believe are planned for retirement in 2010 (we’ll see).
#5 They are not cost effective – they are for research and funded by tax bases – and a significant part of their budget and personnel time is spent certifying, monitoring and repairing – Traveller ships are expensive – 15~30% on annual maintenance would put the TU out of business!

One should also mention the numerous space probes – after 30+ years Voyager 1 & 2 are still ‘going’ (late 70’s) – but keep in mind the following salient points-
#1 See 1-3 above - They are on planned trajectories and again not accelerating (anymore – several gravitational assists along the way)
#2 They are very tiny compared to Traveller starships – Their dispersed structures provide a very small impact area from any given angle
#3 They are not changing directions (back and forth against solar winds nor across orbital paths)
#4 They are unmanned

[Due to power constraint their instruments aren't really 'functioning' any more (intentionally - I think one UV spectro was) - but when they were, numerous allowances had to made for degredation over the years]

(Note these are from 'memory' - so google before quoting any 'facts' :wink: )

 

[BP]

..http://www.netcomposites.com/news.asp?5014

Nice - the A-10 Thunderbolt had self-healing fuel tanks - something I've known since the early 80's and why I mentioned self repairing in my Titaniatum example above - I didn't know A-10's specific method - but I've always considered the survivabilty of the A-10 a good 'quality' standard.

Appears that this particular design went back to WWII.

 

[AndrewW]

One should also mention the numerous space probes – after 30+ years Voyager 1 & 2 are still ‘going’ (late 70’s) – but keep in mind the following salient points-
#1 See 1-3 above - They are on planned trajectories and again not accelerating (anymore – several gravitational assists along the way)
#2 They are very tiny compared to Traveller starships – Their dispersed structures provide a very small impact area from any given angle
#3 They are not changing directions (back and forth against solar winds nor across orbital paths)
#4 They are unmanned

Now don't go forgetting Pioneer (and the Pioneer anomaly). Or the way beyond warranty lifespan of the two rovers still going on Mars.

 

[Ishmael]

OK - was waiting for someone to compare Traveller tech with today’s …

I’ll just list a few key points starting with the Space Shuttle and ISS

#1 Aside from liftoff and re-entry burn (ignoring minor corrections and gravity well), they don’t 'actively' accelerate – and no where near 6G continuous
#2 They actively avoid problems - they are in ‘known space’ with a whole infrastructure of planet-wide, orbital surveillance (including solar flare watch) not to mention historical data.. For example – the ISS is in an orbit high enough to avoid known meteor showers (and of course radiation belts) – it wasn’t placed there by accident and it couldn't survive many other orbits
#3 They do have protection – The ISS has hundreds of shields to protect astronauts and equipment including heavy impact blankets made with Kevlar (like bullet-proof vests, hence my RW analogy above) and a special fabric (ceramic I believe) – and the windows are very thick (multiple pressure and debris panes and not glass) and have metal shutters (I saw a Russian one that irises) and I believe can also be covered with the impact blankets…
The Earth and near Earth environment also provides protection from solar winds, radiation, etc.
#4 Even with all these considered - radiation and to a lesser extent micrometeorites are not insignificant in determining the rated life spans of space equipment. The ISS only had a design life of 15 years – 2015 I think… (not that most space hardware doesn’t last long past their designed lifetimes). And the space shuttles I believe are planned for retirement in 2010 (we’ll see).
#5 They are not cost effective – they are for research and funded by tax bases – and a significant part of their budget and personnel time is spent certifying, monitoring and repairing – Traveller ships are expensive – 15~30% on annual maintenance would put the TU out of business!

One should also mention the numerous space probes – after 30+ years Voyager 1 & 2 are still ‘going’ (late 70’s) – but keep in mind the following salient points-
#1 See 1-3 above - They are on planned trajectories and again not accelerating (anymore – several gravitational assists along the way)
#2 They are very tiny compared to Traveller starships – Their dispersed structures provide a very small impact area from any given angle
#3 They are not changing directions (back and forth against solar winds nor across orbital paths)
#4 They are unmanned

[Due to power constraint their instruments aren't really 'functioning' any more (intentionally - I think one UV spectro was) - but when they were, numerous allowances had to made for degredation over the years]

(Note these are from 'memory' - so google before quoting any 'facts' :wink: )

hey! I wasn't the first person to mention the space shuttle!

The space shuttle is the closest thing to a spaceship we have real knowledge about so far, so....
Most trav rules say ships must have a minimum AV of 40... 20cm of hard steel or about 6cm of modern depleted uranium composite armor. That's just overkill imho. I understand today's "ships" are armored to a certain degree, but with greater protection than a tech13 grav tank ( from a published example vehicle )???
I mentioned the spaced armor idea based on an old paper by W.VonBraun I saw once concerning micro meteor protection without requiring a large mass. The idea is that the micro meteor becomes a plasma jet at impact with the sacrificial layer and the cone shaped jet is dispersed a bit by more layer and the area the impact increased so it has a less chance of penetrating. ( impact energy per impact area ).

about the points you raise.
#1 the ship's acceleration means little as its the relative velocities involved at the time of impact that matter... it doesn't matter if the ship is accelerating at 6g or 600 g or .6 g.
#2 presumably, most traveller worlds have similar infrastructure for in-system navigation for .plotting out orbits and 'stuff' in them... it's the job of the IISS to keep such data up to date. Shipping lanes are likely to take such data into consideration when in-bound or out-bound trajectories from the main world are plotted
#3 I'm not saying ships should have little or no protection, just that the level required by trav's rules seems much greater than real-life; I doubt the various panels and impact blankets are equivalent to 20cm of hard steel.
#4 I don't feel I can discuss radiation shielding as trav doesn't bother with it either, but our only real data points for long term equipment in space are the Voyager missions and they are still going despite not being inside of a modern AFV for micro meteor protection.
#5 Of course they are not cost effective... they are one-off designs, pretty much hand-built. They would not have the cost efficiencies of a traveller spaceship's mass production. Nor do they have the infrastructure dedicated to maintainence and repair that trav ships enjoy.

about space probes.

#1 same as #1-#3 above.
#2 okay...that one's true.. the chance of impact increases by (increase in volume)^(2/3); a ship with 8 times the volume will increase its cross-sectional area such that it'd have 4 times the impacts ( assuming a constant density of micr meteors to impact with).
#3 I'd put this in the "planned trajectories" group. Flight paths will be chosen to avoid danger and changes in direction will be to avoid danger as well.
#4 as they are unmanned, they wouldn't have the added protection/armors given to protect a crew. With less protection than the space station, for example, they still function for years in deep space.

they are still working though
http://voyager.jpl.nasa.gov/mission/weekly-reports/index.htm
amazing to me!

I just don't think Traveller spaceships should have tank armor as per the rules... allow less armor even if it might mean an increase in maintainence or chance of danger. ( I handwave radiation issues away like a pesky mosquito .. it would only pop up if the plot wanted it )
This is important to me as I actually use mass when determining performance. ...and I actually use reaction drives ( HePLAR ) along with fuel limits. I just fudge fuel flow rates... I don't care if exhaust velocity is C.

btw, please don't take my lack of 'smileys' as meaning I'm being belligerent.
I just don't like using them; I think my kids use them way too much.

 

[lastbesthope]

I think the biggest problem for ships is micrometeoroid impact - Traveller has usually ignored this, but a ship travelling at any clip is going to have big problems if it hits something. Heck, a tiny paint chip in Earth orbit almost cracked the shuttle's windscreen, and the shuttle's not even under any significant acceleration while in orbit - imagine what all the interplanetary dust is doing to the hull of ships going at 1g acceleration.

It's nothing to do with the acceleration of the impacting or impacted bodies, it's to do with the relative impact velocity and masses involved.

Oh, and being really geeky, the shuttle is under acceleration in orbit, of about 1g (g adjusted for higher altitude) that's why it's in orbit. If there was no acceleration it would continue in a straight line at tangent to the orbital path and disappear into the big black.

LBH
(Rocket scientist)

 

[EDG]

It's nothing to do with the acceleration of the impacting or impacted bodies, it's to do with the relative impact velocity and masses involved.

If a ship's been going 1g acceleration for a couple of hours, it's going to have quite a bit of velocity. That said, I guess I'm also assuming that the paint chip isn't going in the same direction as the ship and that they're catching up to it very gradually. So yes, you're right and I wasn't being very clear.

 

[BP]

...Most trav rules say ships must have a minimum AV of 40... 20cm of hard steel or about 6cm of modern depleted uranium composite armor...

That's why I skipped all trav rules between CT and MGT! I haven't seen this in the MGT products (Core and HG).

(see previous post about not providing good seperation between fiction and RW [like having a 5 year old explain how airplanes work].)

BTW: Belligerent is in the eye of the beholder - I don't take posts that way (even when they are meant to be - life's too short)

 

[lastbesthope]

It's nothing to do with the acceleration of the impacting or impacted bodies, it's to do with the relative impact velocity and masses involved.

If a ship's been going 1g acceleration for a couple of hours, it's going to have quite a bit of velocity. That said, I guess I'm also assuming that the paint chip isn't going in the same direction as the ship and that they're catching up to it very gradually. So yes, you're right and I wasn't being very clear.

S'ok, just tyring to keep rookie physics mistakes out of it :lol:

You're right the acceleration leads to speed building up, but at the time of impact it's velocity thatcounts, not how quickly, or slowly I accelerated to that velocity.

For instance, if I get T-boned by a car pulling out of a side road and into my front wheel of my motorbike, the important thign is that I'm doing 30 mph, not whether I gently accelerated to 30 mph obver a half mile, or floored it off the line a block back (not that I'd ever do that :lol: )

LBH

 

[BP]

...Oh, and being really geeky, the shuttle is under acceleration in orbit, of about 1g (g adjusted for higher altitude) that's why it's in orbit. If there was no acceleration it would continue in a straight line at tangent to the orbital path and disappear into the big black.

LBH
(Rocket scientist)

Aha! I knew the resident Rocket Scientist would swoop in here (gotta find a better hiding place - its like he's everywhere)
- that's why I find myself using phrases like 'they don’t 'actively' accelerate'...

[ok- so go ahead and tear apart my numerous blatant 'rookie physics' mistakes - crap I already see several...]

 

[lastbesthope]

Aha! I knew the resident Rocket Scientist would swoop in here (gotta find a better hiding place - its like he's everywhere)

That would be because I AM everywhere :twisted: 8)

LBH

 

[BP]

Moderator = Grandfather? All has been revealed!

[scampers aways, tenacle tipped tail tucked between legs...]
(OH NO! I think I crossed the streams again - that can't be good!)

 

[AndrewW]

(OH NO! I think I crossed the streams again - that can't be good!)

Grandfather is making you think you did that.