Galaxy Stardrive Strength Indices

[Sionnach Glic]

We have almost nothing to go on with slipstream physics so it's possible.

Why didn't you mention that in the thread itself?
And no, we don't know anything about how slipstream works, but it's highly unlikely that the ship would even hold together after being weakened by more than a thousand times. Therefore, it's more likely that the hull was simply never that strong in the first place.

Also, the 'weakned by 1000 times' was in response to a comment about weapons yields that were completely unproven. So the ship needn't have been weakned that much, or even at all.

And our canon evidence is, we've seen the legs hold the ship up on multiple occasions, with no mention of an active system being used.

I've also seen the crew walk around just fine when the ship is in space. Should I therefore assume that they aren't using an artificial gravity system?
Also, they hardly ever mention the SIF at all. And why would they? It's always on. So why should we not assume that a system which helps keep the ship together also helps keep the ship standing? The legs, as they are, are far too small and poorly placed to hold the ship on their own. Therefore, an active system holding the ship up is the logical and most sensible possibility.

[Blackstar the Chakat]

But they've mentioned artificial gravity and SIF fields on occasion, so we know they exist. But they have never mentioned such a thing during landing. And they mentioned tons of other stuff like switching to atmospheric thusters, so why wouldn't they mention an avtive system? On the Demon Planet they had almost no power, why would they put the ship at even more risk? Even Janeway wouldn't be that stupid. We have on-screen evidence that the ship can handle normal gravity, and nothing to suggest that four legs couldn't support it. With their more advanced materials and improved hydrolics holding up Voyager shouldn't be a problem.

And the reason why I didn't bring up Slipstream physics before is because...I didn't think of it before.

[kostmayer]

Just read through the old thread on this topic. Maybe next time I should do that first before reopening the debate

[Blackstar the Chakat]

Just read through the old thread on this topic. Maybe next time I should do that first before reopening the debate

Ya Rochey tends to be a stubborn old man about certain things. It is can be very annoying.

[Deepcrush]

Uhh, I think everyone on this site is stubborn in one way or another.

[Thorin]

The ship weighs 7*10^8 Kg. In a 1g enviroment, the landing struts must exert an upwards force of 7*10^9 N. Assuming the centre of mass is directly above the forward most struts (this is being very generous to your arguement), this means the average area of the struts holding up this mass is about 100m^2. This gives the amount of pressure that the material must withstand at 70,000,000 pascals.

So, the landing struts must be able to withstand 70 million pascals of pressure (70 MPa)
Titanium has a bulk modulus of 110 GPa.
So if those struts were made of titanium, at approximately 100m^2 of area, they can withstand the weight of voyager with only a 0.0636% reduction in volume. That is negligible.
If we even used something with a greater bulk modulus - Molybdenum Nitride, for example, would give a reduction in volume of a mere 0.02% reduction in volume. This is equivalent for the strut, for every vertical metre it is tall, to loose 0.02 mm of it's height. A nice assumption is that these struts are about 10m tall, so over all that distance, they only loose 2 mm of height due to compression.

As these struts will be made out of tritanium/duranium, we can expect a far greater bulk modulus. Now, these calculations are valid for uniform compression - but all the weight is vertical. It is, however, relatively easy to make the compression uniform, by 'wrapping' round a very high tensile strength material round the struts, such as to spread out the compressing force.

If someone is able to prove that my calculations are wrong, or that a tritanium/duranium alloy is significantly weaker than titanium, then just titanium struts could keep up Voyager. Duranium/tritanium alloys could probably hold up about 10 Voyagers ontop of each other.
The end.

[Captain Seafort]

I assume those figures are for vertical struts - how much would the fact that the legs are actually splayed affect the validity of the calaculations?

[Thorin]

I assume those figures are for vertical struts - how much would the fact that the legs are actually splayed affect the validity of the calaculations?

A fair comment. As long as the pressure is uniform (or roundabouts), then it would have zero effect. As I said, it can be made [virtually] uniform by 'wrapping' the struts in high tensile strength material, as it spreads the pressure. However, as you pointed out, it is admittedly harder to make the pressure uniform if the struts are anything other than spherical or plain blocks, but I'm pretty sure it would still be possible, by simply making the 'wrapping' material thicker in different areas. The more complicated the shape of the struts, the more complicated the mathematics to figure out how to make the pressure uniform. But still possible.

Whether or not an SIF is used, really is, to me, irrelevant. SIFs have shown to be fully functioning even in full powerloss, and there has never been a 'real' problem with them in any show. But the facts of the matter are, just looking at the physical capability of materials, those struts can hold up Voyager. There are other variables, but quite simply ones we could not possibly hope to calculate, so we've got to simplify it to say that physics-wise, the struts are viable.

[Sionnach Glic]

Okay, I have a very simple logical way of showing this:
The ship has SIF. Fact.
SIF increases hull strength by a good deal. Fact.
The landing gear are part of the ship. Fact.
Therefore, it is reasonable to assume the SIF also increases the strength of the landing gear. Correct?

Now:
The landing gear appears to be too small to hold the ship up on their own.
Therefore, it is simple to assume it is due to the SIF's influence that the tiny legs are able to hold it up. Yes?

Now, this theory is good because it does not introduce any unknowns into it. We know about SIF's. We know about legs. We know the ship's weight.
What we don't know, is the materials used. We don't know the hull's strength on it's own. My theory eliminates these unknowns, and goes with what we know.
Can you see any problems in that, at all?

But they've mentioned artificial gravity and SIF fields on occasion, so we know they exist. But they have never mentioned such a thing during landing.

They've never mentioned shutting down the SIF while landing. So why should we asume they turn off a system which is normaly kept on at all times?

And they mentioned tons of other stuff like switching to atmospheric thusters, so why wouldn't they mention an avtive system?

They don't need to mention it if it's already on.

On the Demon Planet they had almost no power, why would they put the ship at even more risk?

They still had the power for certain things that would take a lot of power. Again, they never mentioned the SIF going down, so why should we asume it did?
Also, if they had to land then why would they shut off the thing that's keeping them from falling over? It's natural to asume they still had the SIF operative.

We have on-screen evidence that the ship can handle normal gravity, and nothing to suggest that four legs couldn't support it.

We have pictoral evidence that shows the ship shouldn't be able to stand up on it's own. Therefore, an active system is the logical explaination.

And the reason why I didn't bring up Slipstream physics before is because...I didn't think of it before.

Yes, you did. You brought it up in the previous thread, then didn't reply to Seafort's points about it.

Ya Rochey tends to be a stubborn old man about certain things. It is can be very annoying.

Pot. Kettle. Black.
The irony of yourself calling anyone stubborn is quite ammusing.

A nice assumption is that these struts are about 10m tall, so over all that distance, they only loose 2 mm of height due to compression.

I have a couple of pictures that may help us determine how tall the struts are.



They help at all?

<snip>

Okay, that seems fair enough to me.
However, would those calculations assume that the weight is distributed evenly? The pictures above show that the weight seems to be all over the place. Wouldn't that mean the pressure is different, this effecting the calculations?

[Thorin]

Okay, I have a very simple logical way of showing this:
The ship has SIF. Fact.
SIF increases hull strength by a good deal. Fact.
The landing gear are part of the ship. Fact.
Therefore, it is reasonable to assume the SIF also increases the strength of the landing gear. Correct?

Agreed. But we're talking about whether it would need it otherwise it would collapse, or whether it would need it just for extra strength.

Now:
The landing gear appears to be too small to hold the ship up on their own.
Therefore, it is simple to assume it is due to the SIF's influence that the tiny legs are able to hold it up. Yes?

Appears is a very, very, very, subjective word. From my point of view, no. Because I always convert things to numbers.

Now, this theory is good because it does not introduce any unknowns into it. We know about SIF's. We know about legs. We know the ship's weight.
What we don't know, is the materials used. We don't know the hull's strength on it's own. My theory eliminates these unknowns, and goes with what we know.
Can you see any problems in that, at all?

As I said, my numbers wouldn't work if it was weaker than titanium. But why on earth it would be weaker than what we make fighter planes out of today, when we have cannon hulls are made of duranium/tritanium, which are stronger (surely??) than titanium.

We have pictoral evidence that shows the ship shouldn't be able to stand up on it's own. Therefore, an active system is the logical explaination.

It only appears so to you, not to the numbers.

I have a couple of pictures that may help us determine how tall the struts are.



They help at all?

It wouldn't really matter because there's already a percentage reduction in size, so the reduction will be proportional to the size either way, whether it's 1000m or 1cm.

Okay, that seems fair enough to me.
However, would those calculations assume that the weight is distributed evenly? The pictures above show that the weight seems to be all over the place. Wouldn't that mean the pressure is different, this effecting the calculations?

No. The weight of a body always acts where over what we call 'the centre of mass', so whether it's heavier in a particular point doesn't matter, it always accumulates the centre of mass. The centre of mass, I have taken (quite generous to your arguement, as it makes the back legs completely useless) to be directly above the forward most struts. I can assure you, my calculations are correct, as Seafort has seemingly confirmed.

[Blackstar the Chakat]

So in theory we could hold up Voyager using modern materials. Their materials should be more then enough. Rochey, it has been mathmatically proven that it's not nessesary for an SIF field to support the ship, so unless you have something more then 'it doesn't look possible' it has been proven possible.

Also, I've never done pot and I'm not black. And I know I'm stubborn

[Sionnach Glic]

Appears is a very, very, very, subjective word. From my point of view, no. Because I always convert things to numbers.

Good point.

It wouldn't really matter because there's already a percentage reduction in size, so the reduction will be proportional to the size either way, whether it's 1000m or 1cm.

Okay then.

No. The weight of a body always acts where over what we call 'the centre of mass', so whether it's heavier in a particular point doesn't matter, it always accumulates the centre of mass. The centre of mass, I have taken (quite generous to your arguement, as it makes the back legs completely useless) to be directly above the forward most struts. I can assure you, my calculations are correct, as Seafort has seemingly confirmed.

Okay then. Debate conceded.

Also, I've never done pot and I'm not black. And I know I'm stubborn

Actualy, my 'pot, kettle, black' thing was refrencing an old saying "The pot calling the kettle black".
Basicaly, I was pointing out you can hardly have a go at someone else for being stubborn.

[Blackstar the Chakat]

You know what they say, it takes one to know one. And since I am one then I would know one, right?

Well at least we finally concluded one of the longer and harder debates.

[Thorin]

And on a more personal note Rochey, on the previous thread where we discussed this and you may remember me getting slightly annoyed/angry, the reason is because I provided these calculations there, yet they seemed to have been slightly pushed to one side and not talked about again, even though they proved the same thing here as they did there, that the struts could hold up the ship, so I hope you'll forgive me (finally) if you see why I got like I did.

[Sionnach Glic]

You know what they say, it takes one to know one. And since I am one then I would know one, right?

Exactly.

And on a more personal note Rochey, on the previous thread where we discussed this and you may remember me getting slightly annoyed/angry, the reason is because I provided these calculations there, yet they seemed to have been slightly pushed to one side and not talked about again, even though they proved the same thing here as they did there, that the struts could hold up the ship, so I hope you'll forgive me (finally) if you see why I got like I did.

No problem, I recall you posting some calcs in the previous thread. I asked whether some of our more physics-minded members could verify them, and we wandered onto some other stuff instead. I just didn't realise that modern materials would hold the thing up.