Do they really need catapults?

[ShadowEnigma]

I just want to point out that people can stand on moving buses, trains, planes, etc without falling over. If you get use tot he movement of the veseel you tend not to notice it anymore. Granted at some acceleration speed you'd have to hold on or something, but any "normal" acceleration speeds it's not as hard as you might think to counteract it, subconsciously.

[Sparrow]

Originally Posted by ShadowEnigma

I just want to point out that people can stand on moving buses, trains, planes, etc without falling over. If you get use tot he movement of the veseel you tend not to notice it anymore. Granted at some acceleration speed you'd have to hold on or something, but any "normal" acceleration speeds it's not as hard as you might think to counteract it, subconsciously.

A bus or car or plane acelerating slowly may not present much problem... but if the bus / car /plane acelerates heavy and also does cornering you will fall.. a standard bus acelerates at quite low G rate, have in count that a supercar like Top Ferraris acelerates at arround 1G for only like 1 or 2 seconds and then aceleration drops as it looses against air resistance... now the aceleration of a Bus compared to that its ridicolous and even so most people will fall if the bus acelerates to its max without warning and they are not holding into something.. a ship in combat situations would be expected to acelerate and turn fast..and those forces would still act on crew as they dont have any "inertial dampers" and only have rotation providing 1G in one direction..

Back in my degree's days i was one day going with a guy in his 125hp car (wich is not that much and pitifull compared to supercars).. i renember that when he floored the gas pedal, for those seconds of aceleration i couldnt separate my back from the seat.. and that probably was arround 0,3Gs..
I cant imagine bein in an Omega's bridge maning one of those "standing up" consoles and the ship then taking a "simple" 0.5G aceleration.. i would be hanging on the console to avoid "falling" to the backwall .

Hyperion class cruisers made more sense.. all crewmembers on the bridge (the only seen area of the ship) were straped to seats and the seats could move arround if necesary.. that ship would had the edge over the Omegas in agility since it could move in any direction the crew could withstand without blacking out.. that means short burst acelerations of probably up to 6-8G and continued turning easily at 2-4Gs where the Omega with all that people just standing up would had problems doing any movoment superior to 0,3Gs

[weedkiller]

I always liked the idea of gravity chairs like in the novel "Sphere", not the movie. The bridge on that ship had the crew sitting in deep chairs with cushions like a flight suit, which enveloped most of the body to account for changes in inertia. The ship had enough mass that quick, darting movements were probably unlikely, but you would still have to hold onto something without them, kinda like riding your bus.

[Mister Oragahn]

Originally Posted by Neakal

Since launch tubes are a closed environment (unlike aircraft carriers) its probably simply safer and more controllable to use catapults to ensure that Vipers leave the battlestars on full speed.

Obviously. Otherwise the Vipers would have to be shaped like bullets and shells, and the launching tubes like the tubes of rifles and cannons.
With such a design, using the thrusters instead of the catapult would build up a huge pressure behind the fighter, and once it existed the tube, it would probably fart out in silly random directions.
Way to go for a nice by the book take off.

[Mister Oragahn]

Originally Posted by weedkiller

I always liked the idea of gravity chairs like in the novel "Sphere", not the movie. The bridge on that ship had the crew sitting in deep chairs with cushions like a flight suit, which enveloped most of the body to account for changes in inertia. The ship had enough mass that quick, darting movements were probably unlikely, but you would still have to hold onto something without them, kinda like riding your bus.

This design would be limited, since the chair could do nothing to stop your internal organs from smashing into your bones. Pasta inside.
You may gain a very few gees at best, and there's still the limit at which your brain just switches off.
Without magic inertia dampening or some adaptive artificial counter-gravity to nullify any sudden acceleration, you're not going to gain much.

[Sparrow]

Originally Posted by Mister Oragahn

Obviously. Otherwise the Vipers would have to be shaped like bullets and shells, and the launching tubes like the tubes of rifles and cannons.
With such a design, using the thrusters instead of the catapult would build up a huge pressure behind the fighter, and once it existed the tube, it would probably fart out in silly random directions.
Way to go for a nice by the book take off.

That depends on the volume of the thrust of the Vipers ... they dont use rockets as "chemicals" and we dont know how Tylium works... as it sure doesnt work "burning" with oxigen (plus the line from Tyrol mentioning "reactor" being still warm in the miniseries , tought that could mean the engines were still usable)..
One thing is sure.. it has to have an inmense thrust to achieve the calculated up to arround 3000Gs calculated aceleration its capable of.

[Mister Oragahn]

We see that Vipers wait the last moment in order to max out their engines, generally when they're just about to leave the tunnel. For most of the acceleration, the thrusters show they're even below "idle" level.

[Longshaor]

Without knowing exactly how Viper engines function, it's all rather speculative, but it is worth looking at the nearest thing we have to launching a Viper - launching an ICBM out of a submarine. In that, an explosive charge is used to vapourize water into steam, which is then used to shove the missile out of the tube and to the surface. Why not just ignite the engine in the tube? That'd blow out the bottom of the sub and make surfacing again less than likely.

I would submit (no pun intended) that by using a catapult you'd negate any possibility of damage to the airlock end of the launch tube from the Viper's engines.

[Mister Oragahn]

Originally Posted by Sparrow

Even so B5 seated the tone for future shows that tried to be more realistic, like BSG and get away from the old StarWars atmosferic style physics (and even so StarWars oddly doesnt screw's up much, ships fly like if they are planes sure, but we dont see them "stoping" in mid space due to lack of fuel or explosions stop spot on

In fact, we even see the Millennium Falcon fly on some weird axis after contributing to the destruction of the Death Star and you even see that the TIE fighter that crashed in the Death Star II actually struggled against its own inertia and its pilot attempted to point the fighter in the other direction, but the damn thing hit a huge pipe and went bouncin' around like crazy.

That said, the Clones Wars CGI stuff really went down a notch in terms of realism and fucks momentum anytime it has a chance to do so. Plus you got fires in space, always going up. I wonder if that's not caused by Lucas having more responsibilities and never being the one caring about such details.

[Mister Oragahn]

Originally Posted by Sparrow

That depends on the volume of the thrust of the Vipers ... they dont use rockets as "chemicals" and we dont know how Tylium works... as it sure doesnt work "burning" with oxigen (plus the line from Tyrol mentioning "reactor" being still warm in the miniseries , tought that could mean the engines were still usable)..
One thing is sure.. it has to have an inmense thrust to achieve the calculated up to arround 3000Gs calculated aceleration its capable of.

It doesn't really matter what they use. If they had to accelerate in the tubes under their own engines' power, they'd still have to exhaust matter, be it crudely consumed like today, or some fancy ion drive tech. The difference would be that less mass would be needed as particles would be ejected much faster. But the momentum still has to be the same.
Which means that the tubes may have an artificial gravity pointing out, so as to precisely allow the ship's mass to be expelled faster.
But one would ask why bother with such nit nack when a ramp will just do the job? Well, artificial gravity would actually counter the problems of inertia, since all atoms would be pushed in the same direction.
Now, it's hard to prove because pilots are well seated in their ships and they don't get to have head jerk backwards like in the old BSG, so we can't say hey look, their head sits still when they're pushed out.
Another reason suggested by others is somehow getting enough speeds while protected. The nacelles have large amounts of armour, so having your fly through a tunnel to get out would probably be better if they did get some help without burning too much fuel already.

Other than that, the Vipers on their own are capable of enormous accelerations, so they wouldn't need ramps at all if it were solely a matter of acceleration.

[RedneckHamster]

The issue of acceleration vis-a-vis artificial gravity can be solved by powering down any and all centrifuge units during a thruster burn. Realistically speaking, burns make up an astronomically tiny portion of spaceflight.

Regarding catapults:
In astrodynamics, we refer to a spacecraft's overall fuel capacity as its 'Δv (delta-v)', literally meaning change in velocity. This is noted in km/sec, and is a reflection of a spacecraft's ability to increase or decrease its velocity. For a rough metric, roughly 20km/sec in delta-v is sufficient to reach Lunar orbit from Earth. A bit more, and you're looking at a reasonable combat mission profile with emergency reserves.

In the BSG re-imagined series, we can assume 4g acceleration, where g= 9.81m/sec^2 and 170ft launch tubes.
Using the equation (v^2 = vo^2 + 2aΔd), where v= final velocity in m/sec, vo= initial velocity in m/sec, a= acceleration in m/sec^2, and Δd = distance in m, we can calculate the net velocity change from a launch tube.
4g= 4*9.81m/sec^2 = 39.24m/sec^2
170ft = 170ft/3.28m = 51.83m

vo= 0 m/sec
a= 39.24m/sec^2
Δd= 51.83m

v^2 = vo^2 + 2aΔd
v^2 = 0^2 + 2(39.24)(51.83)
v^2 = 0 + 2(39.24)(51.83)
v^2 = 2(39.24)(51.83)
v^2 = 4067.62
v = 63.78m/sec
v = 0.0638km/sec

From this, we can see that the catapult imparts next to no effective change in velocity- the Viper will be travelling at 142.67mph, slow for an atmospheric aircraft!! The basic kinematic equation dictates that it will be more effective to increase the velocity of the carrier craft than to use a catapult.

However, it is feasible to use extremely long electromagnetic launch rails. In my writing, I use a 3.125-mile-long track at constant 10g acceleration to save 1km/sec Δv. It is stressful on the fighter's crew, but imparts 15.67 times the velocity of a BSG flight tube.

[Caldumidoan]

It's not so much about the numbers, but the need for the Vipers to get a boost from the battlestar in the first place. The "battlespace" isn't particularly big, perhaps 100 km or so. Battlestars bring them there. And Vipers move relatively slowly relative to the battle's centre of mass. Certainly way below 1 km/s, which wouldn't give pilots enough time to react. (The battle's center of mass may be moving at such speeds, though.)

[Geo]

Besides, it wouldn't do Vipers much good to have a serious boost by the catapults. Once they clear their tube they have to change direction anyway, and that's the harder the more inertia you receive from the launch.
Nah, the most important reason to use catapults at all might as well be that Colonial Fleet doesn't want thrusting engines in the ship itself. Imagine a Viper engine accident in a tube during launch with all this highly explosive fuel onboard.

[Caldumidoan]

According to the Viper launch sequence in the miniseries and the Raptor launch in Dirty Hands, they do actually thrust the engines as part of a pre-launch check. The latter was even on a crowded hangar deck, and the engine did blow up a few minutes later.

I try hard to rationalize stuff, but for the catapults, I've given up. The only reason for using catapults at full speed all the time is because it looks good. Launch tubes make some sense, though. A battlestar can jump straight in and launch two full broadsides, which is more than can be safely launched through the flight decks in one go. The tubes can then be reloaded in parallel, while refilling the hangar deck takes more time.

[ShadowEnigma]

It could be possible that an extended burn is dangerous but a quick check isn't? Who knows. I do think that this may be one of those things that is there to help the audience connect (considering most aircraft carriers use catapults) as well as the fact that yes, it does look cool.

It does give the benefit of not having to do an extended burn in the tube, which would save a little fuel. And theoretically the Battlestar would want to orient the pod to face towards the enemy so the entire side of the vessel should launch straight towards their target. That doesn't help the other side much though.