Topic: SM:P VM Q's 052811

[snrdg051306]

Hello arakish,

I stand corrected and thanks for getting me straightened out on the topic of materials. I'll just say that I'm an ignorant old retired submarine sonar technician.;-)

A space drive is at the basic level a jet engine that creates thrust to move a craft in the opposite direction that the thrust is applied. In vacuum a normal space drives thrust output is more efficient since there is virtually no drag and gravity. Using the same normal space drive in an atmosphere the thrust output has to provide lift to overcome both drag and gravity. A craft floats on or below the surface of water, similar to floating in space, in which case the space drive is providing thrust to move the craft. The major effect is that craft's speed will be slower in each environment.

reentry The event occurring when a spacecraft or other object comes back into the sensible atmosphere after being rocketed to higher altitudes

per The Aviation/Space Dictionary 7th edition Larry Reithmaier p. 271.

sensible atmosphere That part of the atmosphere that offers resistance to a body passing through it

per The Aviation/Space Dictionary 7th edition Larry Reithmaier p. 288.

To me re-entry is similar to landing an aircraft which doesn't stop a normal space drive from working in the atmosphere.

A ship cannot displace the land which means that the drive, a propeller, cannot create thrust in the same manner as the system would in water. By the same token I cannot fly an aircraft, pulled/pushed by a propeller or pushed by a jet engine, through the land either.

Note there are other factors involved with whether or not a spacecraft can actually fly through the atmosphere, float on or below the surface of water.

Running late need to go to the dentist.

Tom R

[Defendi]

the ideas are mutually exclusive because in essence they are both effects that come from making the material stronger.  You are either using less of this stronger material (to reduce the amount used) or using the same amount (to increase the strength).  The house rule works because your finding a happy medium between the two, given the amount that you've improved the material strength.  Doing both separately just doesn't work logically when one of the goals is to use less material, not more.

[markc]

the ideas are mutually exclusive because in essence they are both effects that come from making the material stronger.  You are either using less of this stronger material (to reduce the amount used) or using the same amount (to increase the strength).  The house rule works because your finding a happy medium between the two, given the amount that you've improved the material strength.  Doing both separately just doesn't work logically when one of the goals is to use less material, not more.

 Thanks very much for your thoughts and explanations it makes things a lot clearer.
MDC

[Defendi]

Great.  I was afraid that one made things LESS clear. 

[snrdg051306]

Evening MarkC,

The space shuttle is really a powered glider with the propulsion shutdown while traveling through the atmosphere. The shuttle's nozzles, as you suggest, would not react to well to the cooling effect of water after being used.

To be honest I hadn't considered what Tech Level the thruster nozzles had to be in order to survive immersion into water. I was guessing that the drive nozzles were made of the same materials as shown in the Hull & Superstructure Data chart on SM: P VM p. 98 and should be able to handle the stresses of being immersed in liquid. From the general details I would say any drive nozzle built with Crysteel can be used without being destroyed.

I'm still not sure which tech level stuff like the shuttle and solar panels are at in the SM: P universe. Today the International Space Station's main power source is by using solar arrays, in SM: P they are only used for an emergency source of power. So my thought about Tech Level 17 might be out to lunch.

[snrdg051306]

Evening Defendi,

Great.  I was afraid that one made things LESS clear. 

The explanation was by far better than my attempt, which was OTL on most of the facts. Of course I was close, kind of, when I mentioned needing two alloys.;-)

By the way I would like to say thank-you for a great construction system under the circumstances that SM: P was published. I'm glad that someone pointed to the system.

Tom R

[arakish]

I also stand corrected on some points.

@markc
I did not know you were talking about the reactionless drive.  Forgot about that one.  It could be called a hyper-gravitic drive in a sense.  You are producing force through the application of power/energy.  Sorry.

@snrdg053106
You are correct in the sense that space drive engines can also work in an atmosphere.  You are also correct in that they will not be as efficient as drives designed to work in an atmosphere.  As above, only the reactionless drive would be able to operate in space, atmosphere, and underwater.

@defendi
Yes superior alloys can make a hull stronger to a point.  But to truly strengthen a hull, you would still need to make it thicker or laminate it in layers.  We have always allowed persons to apply a double hull, even HAT XXX can be doubled up if the person is willing to spend for the mass and volume.  We just rule that this will double the ship's hits.  But this is usually only done for the true battlewagons such as Monitor Battleships, etc, since their maneuverability simply makes them sitting targets.  Thus, they need the extra armoring to withstand the extra attention.

Thus, I stand corrected.

rmfr

[snrdg051306]

Small error and correction:

The shuttle's drive is shutdown during reentry, they are being used for climb to orbit sucking up the fuel in the external tank.

[snrdg051306]

Hi again arakish,

Comments about drives and I'm still pondering on the superior alloys. If something filters out I'll be back with a reply to the superior alloys.

I agree that the ion, fusion, and ramjet drives aren't able to operate in an atmosphere or on/below the surface of water. The following is my thinking on which normal space drive system might work for one or both environment.

In addition to the Reactionless drive I would include the second generation drives as capable to provide adequate thrust for short duration atmospheric flight. On the surface of a liquid the location of the drive nozzles and their construction material may or may not short duration operation for propulsion. What I mean by short duration is landing and taking off from the surface. Operating them submerged is probably not a good idea and one I wouldn't use. However, someone might be able to convince the GM that the drive works underwater.

I'd rule out the ion drive based on the systems low thrust output for atmospheric flight and IIRC the small issue of the ionized particles potential to cause damage.

Fusion drives per SM: P VM p. 103 are a crime when used within an inhabited atmosphere because the exhaust is radioactive. However, if the exhaust were not radioactive then the drive might be used for atmospheric and water surface travel. Submerged might or might not be a problem.

Ramjet Drives wouldn't be used because of the low output thrust, size of the magnetic scoop, and the need to accelerate to 1% of light speed.

Tom R

[Ynglaur]

Evening MarkC,

If a drive unit can operate in vacuum and provide propulsion in an atmosphere then I would guess liquid like water wouldn't be a problem. Of course a plot device could be that due to age, a manufacturing flaw, damage, or anything the GM can think of could cause a failure. I think that Chris Bunch in the Last Legion series allowed starships to operate on the water without any problems. Okay, being hit with ordnance did have some negative consequences. I also think that the ships could submerge as well, guess I'll have to read the books again.

Tom R

Not necessarily.  Constructs designed to operate in a vacuum are designed to contain pressure from within.  Constructs designed for liquid submersion are generally designed to withstand pressure from without (assuming the inside of said construct has a gaseous atmosphere, open space, etc.).  It's certainly plausible that an advanced civilization could develop constructs able to handle both...but there would still likely be a cost to do so.

[Defendi]

Thanks.

[Defendi]

I never did much with solar panels because I figure their too limited a technology.  Sure they're probably tech level 25 or whatever, but I suspect you start getting seriously diminishing returns around tech level 18 or 19 and the power requirements of almost any system will far exceed the potential energy in the sunlight they can capture.

[snrdg051306]

Hello Ynglaur,

Absolutely right that the hull is constructed differently for a craft operating in vacuum and submerged. The basic principal in both cases is to keep the people inside the hull alive. In most of the design systems I'm familiar with they hand-wave this little issue away, much to my relief and what little sanity I have left.

Thanks for the reply,

Tom R

[snrdg051306]

Afternoon Defendi,

I have not been able to figure out away to show that a solar array would be a good alternate power source without any success. All the other power sources characteristics are determined by the output of the source, while solar panels are based on the volume and mass of the item to be powered.

The base cost is about the only characteristic that I came see that makes any difference. In terms of powering the ISS the cost is going to be ¢417 based on the mass of the ISS and the solar panel formula. Solar panels are the cheapest solution for everything and TL but a Cosmic Power Generator.

I get the feeling I'm not done but I can't figure out where to go from here.:-(

Tom R

[snrdg051306]

Evening arakish,

Could you please cite the source that was used to conclude that a double hull has double the hit points?

I've scoured my SM: P stuff and the only way I've found to increase hit points is by adding an armor belt to a maximum of 25% of the normal material, SM: P VM p. 99.

Tom R

[markc]

 I do not know of any source that says double hull is x2 hull hits. I do know of an SM2 rule for XX double hull that gives +50 DB.



MDC

[snrdg051306]

Morning MarkC,

To me referring to SM2 is citing a source, which I thank-you for the information. Unfortunately, I haven't found the source in SM2 SpaceMaster Companion I (Stock # 9002 ISBN 1-55806-135-5), Armored Assault (Stock # 9020 ISBN 1-55806-060-X), or Star Strike (Stock # 9010 ISBN 1-55806-051-0).

CAT 30 (XXX) Ordium II has a cost multiplier of 50, other than that

Wait a minute the minimum SM2 CAT is 21 (XXI) and the maximum SM: P is XX (20).

Did the web gremlins sneak in and change the words?

Dirty little buggers if they did;-)

Tom R

[snrdg051306]

Darn-it, MarkC I forgot to ask if you could possibly dig-up the source you recalled about the +50 DB for a double hull.

Thanks again,

Tom R

[snrdg051306]

Hello arakish,

Answering MarkC's reply  my brain finally noted that in the reply to Defendi on superior alloys the material code was CAT XXX.

SM: P CAT material codes go from XI to XX, while SM2 codes are the CAT 21 (XXI) to CAT 30 (XXX).

Is the CAT XXX really CAT XX?

 Unfortunately, I still haven't found any mention of doubling hit points for a double hull of the best CAT material in either SM: P or SM: 2.

I also seem to have a different idea of double hull construction and hit points.

To me a double hull is a modified single hull that splits the designs total mass between outer and inner plating.

Here is my understanding of hit points per SM: P VM p.100. a design's base hit points is equal to the mass of the construct regardless of the CAT Material code used. A 100-ton construct using a single, reinforced, or double hull CAT has a base hit points of 100. To increase the hit points you need to add an armor belt, which also increases the DB per SM: P VM p. 99. The maximum DB and hit points the 100-ton design can have is +25 DB and an additional 25 hit points for a total of 125 hit points regardless of CAT type.

In the reply to Defendi

We have always allowed persons to apply a double hull, even HAT XXX can be doubled up if the person is willing to spend for the mass and volume.  We just rule that this will double the ship's hits.  But this is usually only done for the true battlewagons such as Monitor Battleships, etc, since their maneuverability simply makes them sitting targets.  Thus, they need the extra armoring to withstand the extra attention.

I'm getting the impression from the above quote that a double hull is two complete hulls joined together which would double the hit points by doubling the mass of the design. Of course I'm probably totally lost in space in my understanding. ;-)

Tom R

[markc]

 I do not remember exactly where I remember the rule from but it maybe from a SM2 companion or adventure or errata. I will try and dig up my source when I have a chance. The rule just increased the volume % of CAT XXX (Single) which IIRC was just mass like armor. I think this rule grew out of tec advances in the game world and the unique structure of CAT XXX.


 Yes in SM2 vehicle armors are in the 21-30 range and in SM:P they use I-X human armor and XI-XX for vehicle armor.


MDC