Pepsi Jedi, Shinobi Killfist, KarmaInferno...thank you guys for actually Getting It. I, personally, have always used "I saw this on A-Team/MacGuyver/Knight Rider" as an excuse to
allow something...

That tank was an APC. If you see the back of the tank it had a door (and a bumper sticker asking "How's My Driving?").

Ahem. Myth busted.

Yes....but who cares if it is COOL!™?

and people wonder why science is taking a back seat to beliefs these days...

As I said, its great for the A Team. It is significantly less cool if anyone else does it.

Or maybe science just doesn't have to matter as much in a Shadowrun game as it does in real life.

Actually all modern tanks can submerge themselves for short periods of time - or at least I know the Abrams can, I saw them do it. That was the least far-fetched of all the circumstances.

Most of them have snorkels, but complete submergance is rare.

But possible. If they go underwater they can drive themselves out.

I know Cardul didn't want to hear this, but that scene really was a poster child for the Hand of God use of permanent Edge burning. It just happened to have a fantastic GM describing what happened!

I mean, just look at everything that happened from the beginning. They're sitting in the cockpit of the transport with B.A. unconscious and strapped into a seat behind them. As the missiles approach, they're still up there... but by the time the explosion happens, they've all miraculously made it into the APC down in the cargo hold and have somehow not only managed to carry the massively huge B.A. but also had enough time to strap him inside. That alone defies description.

But I guess if you want to adhere to Cardul's wishes, you could say that was the Hand of God portion. They did, in fact, manage to survive instant destruction. They just also happened to be placed in extreme peril as a result; namely plummeting to their doom in an APC.

So if you assume all of that, and both the GM and the Players are having a ton of fun with the idea (which completely and utterly trumps all the naysaying about how unrealistic it is), well, it still depends on how you want to approach it. If I were in that situation (and I probably wouldn't as I prefer something between the Pink Mohawk/Stone Cold Professional scale), I'd probably split it into two distinct acts. The first would be to aim the tank. That's probably the most believable (again; believability trumps realism) part of the whole thing. Off the cuff I'd go with the teamwork rules with Hannibal's Military Tactics + Logic test augmenting Face's Gunnery rolls, with both of them using Edge to either reroll failures if their pools are big enough (and they likely are since they're the friggin' A-Team) or augmenting each roll to take advantage of any 6's that come up. I'd make it an Extended Test with, I dunno, maybe a threshold of 12 and a time interval equal to the reload time of the cannon. Two or three teamwork rolls by guys of their caliber would easily net that, and hey, that's about how many shots it took for them to get over the lake.

The hard part is figuring out how to handle the landing itself. Using whatever Edge they have left would definitely be a must, but figuring out the exact roll(s) is tricky. It's technically crashing, so I'd look to those rules and have Face using Gunnery in place of a vehicle skill. So it'd be Gunnery + Reaction (+Edge) augmented by Hannibal's Military Tactics + Logic (+Edge), but I'd increase the Threshold due to the circumstances. Probably put it at 6 or so. If they make it, minimal damage to them and the APC. Otherwise, I'd use the Ramming Damage Table to determine what they have to resist... and it's not pretty.

But yeah, in a nutshell: Hand of God to get into the APC, then Gunnery/Military Tactics teamwork rolls augmented by Edge to the bitter end.

As I understand it it is possible if the snorkel is not submerged so it can still suck in air. Middle of a lake looked pretty damn fully submerged to me. But I could totally be wrong.

Even if I knew the science on this I'd let it fly.

1 Surviving chute, um 1/2 the damage from a terminal velocity fall. A water landing, people if they hit the water feet first can survive some serious water landing falls as they pierce the water instead of splatting on it. I don't know why, I just know it happens. Nose first tank, I'd give the same benefit, maybe 1/2 the damage again. Gunnery tests= to a gymnastics test to reduce the damage from a fall.

Does anyone on the no way side of the equation actually know how much a single chute would slow the tank down, or are they making guesses based on what they think the world works like? This isn't meant as a knock, I'm curious if anyone here actually knows what they are talking about other than quoting basic velocity numbers.

Um having seen the movie twice now that is somewhat wong. First engine blows out, murdock makes obligatory joke comment. Next scene you are with the military types trying to get in contact with the drone pilots to stop them from shooting it down. Then a missile fires and takes out the plane. We have no idea what they are doing during that time frame, so as soon as the first engine blew they may have gone for the tank we don't know because it is happening off camera.

Eh. Just unstrapping B.A., figuring our how to carry him down into the cargo area, loading him in, and strapping him down again would have taken several minutes all by itself. There was less than half a minute or so between those two scenes. Still, I'd treat the whole thing as a Hand of God, period. Because that really is all it was. They were completely screwed.

Depends on the type of engine. Any sort of engine that requires oxygen to burn fuel can't be submerged (must have a snorkel). Even old school submarines could only submerge as long as their batteries were charged (they charged up batteries using diesel fuel with a snorkel or on the water's surface). One of the primary reasons subs are nuclear powered is because nuclear reactions don't require oxygen.

In the Shadowrun future one could easily say that battery technology has progressed enough to power a tank underwater for X amount of time.

Most people don't survive falls into water from any significant height. Trained divers (like cliff divers) can jump from extreme heights but even a 30 ft dive can seriously cripple/kill someone if they don't hit the water well. Surface tension of the water is what causes the effect you are speaking of. Breaking the surface tension of the water with your feet makes it easier for the rest of your body to pass into the water - but a lot of people break their legs/hips even if they hit feet first. The Golden Gate Bridge is only 200 or so feet above the ocean but most people that jump off the bridge die on impact.

As far as the tank's velocity - you need to know the mass of the tank and the surface area of the parachute.

Yeah the golden gate is a suicide spot of choice though they have been trying to stop that. But IIRC last year or the year before someone jumped and hit the water right or wrong actually since he was trying to kill himself and got out with a broken arm I think it was. I've done a 50' cliff jump and I got out fine. My sister jumped first and while it was mostly correctly, her ass hit a bit more than it should of so she surfaced screaming in pain. Which she then followed up with come on jump its not to bad. After that vote of confidence I still jumped or as she described it I stepped off the cliff and I didn't feel a thing. I had a harder time making it back to the boat in the currents than I did making the jump. I have no idea if tanks can hit it right and I doubt it is high on the list of things the government wants to test, but I'd give it to the players.

Point being while all of this is massively implausible to me, it is also massively awesome to me. And since it does not fall into the totally impossible camp IMO I'd let it roll if the players had come up with this plan. Thanks for the information on engines etc. it is interesting to know.

Actually this is an apples and oranges type of deal. The clip you posted only had a hammer hitting the water a split second before the dummy. That STILL reduced the g-force felt by the dummy from 296 G's to 270 G's.

Now take an explosive tank shell hitting long before the tank does... and the tank is still firing so you are still breaking the surface tension, then the tank hits.

I don't know how much it would reduce the surface tension, but it would be more than what the MythBusters were able to create.

So instead of "rip your limbs off deadly" it was just "break every bone in your body deadly."

I suspect a tank would be in much the same position.

Also keep in mind that a tank will fall (even with a single chute) at greater than 60 mph and have more mass, resulting in a higher force collision with the water's surface. Even a 50% reduction on the Gs* there is still going to cause the tank armor to shatter. Plus liquefy anyone inside the tank.

*Assume the tank weighs a mere 100 times more than a person (an Abrams tank weighs almost 1000 times the average human) and assume that it travels at the same falling speed (unlikely, given previously posted details about falling cars). Upon impact with the water's surface you're looking at a base 29,600 Gs. Reduce by half (for a generous 50% reduction in force for breaking the surface tension) and you get a whopping 14,800 Gs. That's the level of force electronics built into military artillery shells are expected to survive.

A tenth of that is the projectile in a space gun with a barrel length of 1 km and a muzzle velocity of 6 km/s (assuming constant acceleration).

One twentieth of that gives you the maximum brief human exposure with probable survival in a crash (100 Gs--maximum ever survived was 179 G after crashing a car at 110mph which decelerated to 0 in 50cm. Highest ever voluntarily subjected to was 82.6g for 0.04 seconds by Eli L. Beeding Jr. in 1958. He spent 3 days in the hospital.)

So no, you will not be crashing an Abrams into a lake at any degree of "speed" and expect to survive. Even given extremely lenient math on the physics.

(1) As has been stated, it wasn't an Abrams. It was an actual model of tank designed for being air-dropped, meaning someone smarter than you (or me, or him, or her) thought -- at some point -- it was a reasonably good idea to try this sort of thing. No, that doesn't mean it would work just like it did in the no-brainer popcorn summer action flick, but it might mean that you're overthinking it a little.

(2) Rule of Cool. What works at some game tables with flying colors won't work at others. Why argue about who's right?

There is no doubt in my mind that if the situation somehow arose, or one even similar to this, I would with, gleeful joy, allow my PCs to do something like fly a tank. They would just have to resuscitate me first, due to the fact that I'd have died laughing.

Impossibility makes Legends. Can someone truly fly a tank? No. Can we really barrel roll medical helicopters? No. Can we really free fall thirty stories and then lock the zip line to swing in a window without getting hurt? No. But we play our games to have fun. And in the spirit of sheer awesomeness and classical Pink Mohawk Shadowrun goodness I will propose my ruling on "Flying a Tank"

Flying a Tank

Step 1: Decide on how to "Pilot" a tank in midair.
A) Gunnery here seems like the best option in an attempt to steer the tank.
B)Every hit on a gunnery test, allows the tank to move it's low acceleration number once.

Step 2: Determine Speed of Falling Tank in SR4A Rule sets.
A)Terminal Velocity is approximately 80 meters per second.
B)A SR4A is 3 seconds long.
C)Thus a tank is moving 180 meters per turn.

Step 3: Determine ramming damage for a falling tank.
A)The Ramming Chart on page 169 SR4A says that between 61-200 meters per turn has a damage value of Bodyx2
B)The body of the tank is about 25-30. But well say 30, just for big numbers sake.
C)Therefore the tank is taking 60 damage. Resisted by Body+Armor (Half-Impact only applies to falling characters)
D)The tank falling into water would reduce the amount of damage by I'd say somewhere between 25% and 50%. But for Pink Mohawkness we'll say 50% (We do want them to succeed and all.) So, 30 Damage total.

Step 4: Resist Damage of falling tank.
A)A tank with a Body of 30 and Armor 20 is rolling 50 dice.
B)Taking hits(Which is low balling the guess, IMO), gets you to resist 12.5 damage. Round up to 13
C)That leaves you with 17 damage left to deal with.
D) So, tank takes 17, leaving it with 5 boxes remaining.

Step 5: Resist player Damage
A)My ruling has always been passengers take half the damage the car does when it smashes into something.
B)So PCs are each taking 9s, resisted by Body+Half Impact (Because they's still effectively falling)
C)Average Body of 3, with an Armor Jacket(8/6), and PPP Tech System (+2/+6)
D)That gives you 3(Body)+6(Half Impact). Total of 9 Dice
E)So you resist 2, by taking hits again lets say for average sake. So, 7s all together.

Conclusions
So everyone in the tank takes 7s. Definitely enough to shake them, and if anything else happen, they're pretty much boned. But the tank is still operable (Down the condition track, but hey, it can move). So as long as everyone didn't pass out, I'd say they're good to roll on out and ask for directions at the nearest old lady.

The Abrams was merely an example to compare to what I was using the math on. I was applying the physics to a tank that weighed 1/10th of an Abrams (and still liquified its passengers). The lightest tank I can find (Google is being unhelpful and returning paintball and scuba gear) is the Stingray, just shy of 50,000 pounds. Or over 300 times the wight of your average person (bumping my math previously posted by triple: Base impact of 88,800 Gs).

(I am, of course, assuming that the tank and the human being decelerate at the same rate upon hitting the water's surface, which is likely not true, but I don't have any math I can use to calculate what that rate might be. So I'm just assuming that in F = ma that 'm'ass increases a hundred/three hundred fold).

Rule 11: Everything is air-droppable at least once.

On that note, tanks are heavy. You'd need a lot of parachute to slow them down. A lot. You'd also make a tempting target on the way down,as firing that main gun is going to kill your stability.

Most tank-drop experiments had the crews seperate from the tanks, to minimize tank crews getting turned to salsa should that tank land wrong.

Also: Just because there was an experiment doesn't mean it was a reasonably good idea.

i'm not sure you understand what exactly 1 G is. weight/mass is not applicable.

You will, with relative ease, in a Pink Mohawk style game in which the original poster (and several others in this thread) were running. RealWorld™ physics need not apply.

Especially since even in a non-pink Mohawk campaign you can easily say 1 chute in 2074 handles are shit ton of weight fine, the 3 are only for stabilization and making sure it lands right etc. The chutes of the future do not have to have the same limits as the chutes of today.

It is when you're crashing into something (eg. the hard stop at the end of a fall).

Acceleration in that context has nothing to do with gravity (but can still be measured in Gs).

Force equals Mass times Acceleration.

Force (Gs) = Mass (20 ton tank) * 60mph -> 0mph in 6 seconds.

* The g-force acting on a stationary object resting on the Earth's surface is 1 g (upwards) and results from the resisting reaction of the Earth's surface bearing upwards equal to an acceleration of 1 g, and is equal and opposite to gravity. The number 1 is approximate, depending on location.
* The g-force acting on an object in any weightless environment such as free-fall in a vacuum is 0 g.
* The g-force acting on an object under acceleration can be much greater than 1 g.
* The g-force acting on an object under acceleration may be downwards, for example when cresting a sharp hill on a roller coaster.
* If there are no other external forces than gravity, the g-force in a rocket is the thrust per unit mass. Its magnitude is equal to the thrust-to-weight ratio times g, and to the consumption of delta-v per unit time.
* In the case of a shock, e.g. a collision, the g-force can be very large during a short time.

It's not the strength of the chute - it's the surface area. The strength is in the cords holding the tank to said chute - and enough of them could probably well hold a tank of that weight. But you'd need some serious surface area to make sure that tank actually slowed down - it's like trying to use a standard-issue umbrella to jump off a six-story building.

Just my two cents on the topic of hitting water.

IMHO it's not the surface tension of the water that cause the problem, it is a really weak effect - the kind that prevent dust or small insects to sink but not much more. Reducing it won't do you much good.

It's the inertia and viscosity of the liquid and the force you must exert to push it away to make room for your intrusion into the new medium. A good dive will focus the forces on the diver in a direction his body is more able to handle, move relatively little water and loose it's speed comparatively more slowly, minimizing stress to the diver.

In contrast in a belly flop you're basically trying to force a rather large volume of water to suddenly move in the same direction as you, slowing down much more abruptly and sustaining those forces in a direction our body is not really designed to handle.

Exploding tank shells n won't help much with that unless you have an extremely good timing. It can even make things worse. You may have seen pictures of underwater explosions, with that huge pillar of water rushing upward. In fact it's not directly the explosionthat creates the pillar, it's the displaced water rushing back and expending it's energy in a direction where there is less resistance - up.If you're unlucky this will add a lot of water rushing at high velocity toward you, increasing the brutality of your crash into the water rather than reducing it...

Fine add the line and creates enough surface tension. Heck do we even know if in todays day and age when these drops are done why they use 3 chutes. Does 1 chute create enough surface tension and the others are there for redundancy, stability or other issues and not just slowing it down. Maybe they only need 2 chutes and the 3rd is for redundency but one chute still slows it down a heck of a lot. They are dropping a multimillion $ vehicle maybe 3 chutes is huge overkill.

yeah, you might want to look at the second-to-last point also. notice that it is "per unit mass". (edit: to clarify, thrust is roughly synonymous to force. if you take force, and then divide by mass... you get acceleration. 'F = m * a' is equal to 'a = F / M', right? /edit)

you calculate the number of Gs by taking the *acceleration* and dividing that into the acceleration due to gravity. in no case does it matter how much the object weighs (although that would certainly apply if you were calculating force over all, it is not related to the number of Gs something is experiencing).

this is not to say i don't think the tank falling from an airplane into a lake isn't likely to be lethal... but g-force is a measurement of acceleration, not force.

This thread is a perfect example of what DS is. A discussion on whether you would allow an awesome over ther top cinematic maneuver turns into dueling physicists. Man, I love this place.

Today this tank is NOT DROPPED, thoses "chutes are Drag Chutes, the tank is supposed to roll off the cargo bay at very low heigth and the chute are there so he slow down and keep in the horizontal.

They are not designed to sustain it in gliding mode...