Mobile Suit jumping and landing on earth

[Jameedaark]

Hello everybody. After reading several posts and reviewing the animated series, I was wondering, with the official data from the Gundam 0079 series, how mobile suits could jump and land on earth. For example, we often see zaku, gouf and the gundam himself doing hovering and soft landing maneuvers. With thrusts of the order of 0.65g or even the gundam of 0.93g it would be impossible in my opinion. Is it possible that they have a surplus of thrust not mentioned in official sources? Thanks to who will answer me.

[MythSearcher]

Hello everybody. After reading several posts and reviewing the animated series, I was wondering, with the official data from the Gundam 0079 series, how mobile suits could jump and land on earth. For example, we often see zaku, gouf and the gundam himself doing hovering and soft landing maneuvers. With thrusts of the order of 0.65g or even the gundam of 0.93g it would be impossible in my opinion. Is it possible that they have a surplus of thrust not mentioned in official sources? Thanks to who will answer me.

You can jump without thrust, all you need to do is to squat down and stand up really fast.
The thrust helps them jump higher(and fall slower) but isn't necessary for jumping.
With a thrust of 0.65g for example, if they keep it on for the duration of the jump, they will experience a 0.35g of downward acceleration, so it will be similar to something of Mars.(at 0.38g)
So how high they can jump will depend on the take off velocity v their legs can give them and the simple Physics of trajectory.

[Seto Kaiba]

The beauty of what are essentially thermonuclear hydraulics... Mobile Suits can produce some frankly terrifying amounts of torque.

[Jameedaark]

Hello everybody. After reading several posts and reviewing the animated series, I was wondering, with the official data from the Gundam 0079 series, how mobile suits could jump and land on earth. For example, we often see zaku, gouf and the gundam himself doing hovering and soft landing maneuvers. With thrusts of the order of 0.65g or even the gundam of 0.93g it would be impossible in my opinion. Is it possible that they have a surplus of thrust not mentioned in official sources? Thanks to who will answer me.

You can jump without thrust, all you need to do is to squat down and stand up really fast.
The thrust helps them jump higher(and fall slower) but isn't necessary for jumping.
With a thrust of 0.65g for example, if they keep it on for the duration of the jump, they will experience a 0.35g of downward acceleration, so it will be similar to something of Mars.(at 0.38g)
So how high they can jump will depend on the take off velocity v their legs can give them and the simple Physics of trajectory.

Look, I know it's possible to jump even without rockets. But using a simple ballistic calculator, with a thrust of 0.65g and a leg thrust of 1.4g, the zaku would make a jump of 163 meters in length or 80 in height at most. In addition to falling with a mass of 70 tons from 80 meters with an acceleration of 3.43 meters per second, it seems to me a good way to crash.
In the animations for example of 0083 it is clearly seen that the rear rockets are able to support a zaku even if it is about to fall, so they must at least have a max thrust of 70 tons or so ...

[Jameedaark]

The beauty of what are essentially thermonuclear hydraulics... Mobile Suits can produce some frankly terrifying amounts of torque.

Nice useless answer.
Sure nuclear hydraulics create a lot of power, but if a zaku is running at max 80km / h, I don't think it jumps with 5g of power. And the problem of the landing is not solvable with only the torque of the legs, I suppose.

[Seto Kaiba]

Nice useless answer.
Sure nuclear hydraulics create a lot of power, but if a zaku is running at max 80km / h, I don't think it jumps with 5g of power. And the problem of the landing is not solvable with only the torque of the legs, I suppose.

No, it quite adequately explains where the difference in power is coming from... we're talking about a drivetrain that has the power to take a 75,200kg MS from a standing start to an 88km/h run in a matter of a second or two. There is more than enough torque to give a Mobile Suit a vertical jump of considerable height on its own. Assisted by rockets and its own pre-existing horizontal velocity, that's enough power for quite a jump once you factor in the mobile suit's initial velocity.

There are cases in, for instance, MS IGLOO where Zaku II's are shown hopping a dozen or more meters into the air and 20-30m laterally seemingly without any intervention from their rockets at all.

[Jameedaark]

Walking at 88km / h for an 18m tall robot is equivalent to a 1.8m human walking at 8.8km / h. Not a great speed. It sounds like a lot from a man's point of view but with 10m long legs it doesn't seem like a big deal. Of course, a zaku definitely has the strength to jump ten meters without rockets, but Igloo is not a great example, as much as pseudorealism. Better 0079 or 0083 or 08thms team. Returning to the jumps, if we are in the pseudorealism of the official data, a zaku could make vertical jumps of up to 80 meters. Which can also be there, because the problem of going much higher is the fall. From 80 meters with ignited rockets, it would fall in about 7 seconds at a speed of about 80kmh. Probably the legs of the zaku are able to cushion the impact of 70 tons at 80kmh with the ground. Or at least I hope so, for the sake of the pilot. Having a few extra pounds of thrust would be better for softer landings.

[domtropen]

IIRC in 0079 even stock Zaku II can make a quick repetitive 18 meters hop without any rocket assist. And for Char's Zaku during the Garma death fight it can jump very far, very high and very fast without rocket assist too.

[Underrated GM Custom]

What always surprised me about the Zaku's jumping was that they could land without causing massive damage to their internal motors and servos. I can only imagine the size of the shocks and dampeners inside those suits in order to make that work. Talk about impact testing.

[MythSearcher]

Look, I know it's possible to jump even without rockets. But using a simple ballistic calculator, with a thrust of 0.65g and a leg thrust of 1.4g, the zaku would make a jump of 163 meters in length or 80 in height at most. In addition to falling with a mass of 70 tons from 80 meters with an acceleration of 3.43 meters per second, it seems to me a good way to crash.
In the animations for example of 0083 it is clearly seen that the rear rockets are able to support a zaku even if it is about to fall, so they must at least have a max thrust of 70 tons or so ...

I don't think they jump to 80m in show, the furthest a Zaku jumped as I recall was in 08th where it was more like 40m and maybe around 160m in length.

Also, if it's legs can take the jump, it can take the fall. The acceleration is essentially the same thing, considering drag is making it slower during the jump, it should actually be slower than the initial speed. Just like why you can always land if you initiated the jump and did not have a great height difference from where you jumped. (I mean, if you intentionally jump off a cliff or building, that is obviously not a regular jump we are talking about in this situation)
Look at a simple projectile Physics question neglecting air resistance, your initial speed will always by the same as your final landing speed because it is a mirror image. Since the initial speed is delivered by your legs, the final speed can be softened by your legs, its the same mechanical procedure in the opposite direction, but the force and impact you are taking are the same, and a machine is definitely more qualified than a human in that.

In 0083, they are not really supporting their fall but slowing it down. That is why they are jumping and not flying.

That said, I doubt they need to use full weight in ground combat.
I can understand why they carry to their full capacity in space because they needed the propellant, but on the ground, they likely only have to carry their weapon weight, they do carry some propellant, but likely limited, and some ground modifications may change them to thermonuclear jets instead of rockets.

[Jameedaark]

Look, I know it's possible to jump even without rockets. But using a simple ballistic calculator, with a thrust of 0.65g and a leg thrust of 1.4g, the zaku would make a jump of 163 meters in length or 80 in height at most. In addition to falling with a mass of 70 tons from 80 meters with an acceleration of 3.43 meters per second, it seems to me a good way to crash.
In the animations for example of 0083 it is clearly seen that the rear rockets are able to support a zaku even if it is about to fall, so they must at least have a max thrust of 70 tons or so ...

I don't think they jump to 80m in show, the furthest a Zaku jumped as I recall was in 08th where it was more like 40m and maybe around 160m in length.

Also, if it's legs can take the jump, it can take the fall. The acceleration is essentially the same thing, considering drag is making it slower during the jump, it should actually be slower than the initial speed. Just like why you can always land if you initiated the jump and did not have a great height difference from where you jumped. (I mean, if you intentionally jump off a cliff or building, that is obviously not a regular jump we are talking about in this situation)
Look at a simple projectile Physics question neglecting air resistance, your initial speed will always by the same as your final landing speed because it is a mirror image. Since the initial speed is delivered by your legs, the final speed can be softened by your legs, its the same mechanical procedure in the opposite direction, but the force and impact you are taking are the same, and a machine is definitely more qualified than a human in that.

In 0083, they are not really supporting their fall but slowing it down. That is why they are jumping and not flying.

That said, I doubt they need to use full weight in ground combat.
I can understand why they carry to their full capacity in space because they needed the propellant, but on the ground, they likely only have to carry their weapon weight, they do carry some propellant, but likely limited, and some ground modifications may change them to thermonuclear jets instead of rockets.

I partially agree. My calculations are based on zaku data and math formulas of a ballistic online calculator.
Obviously they are not accurate but they give an idea.
Regarding the jumps, if you look at the episode in which Ramba Raal and the Gouf appear, both Zaku and Gouf do some nice long jumps with the help of the backpack. Clearly in 0083 we are talking about vehicles with even greater power in the backpack for which they almost fly.
I agree that the legs should be able to cushion the landing. Also, as you say, they probably don't load much fuel on earth, they can't fly anyway. They will carry the fuel needed for a limited number of jumps.

[Jameedaark]

I don't think they jump to 80m in show, the furthest a Zaku jumped as I recall was in 08th where it was more like 40m and maybe around 160m in length.

Yes, my calculation on zaku j result in a maximum vertical jump of 80 meters or if it jumps at a 45 degree angle, about 170 meters in length and about 40 in height. The Gouf B is similar.

[Underrated GM Custom]

Also, if it's legs can take the jump, it can take the fall.

Not necessarily. Yes if we treat it as a simple physics problem and the forces are roughly equal going up and going down but that's assuming a perfect landing. Just like humans we can jump and land no problem, but it's a different story if you screw up the landing and roll your ankle.

Then we have to take into account that a MS components are primarily metal which have way different ductility and loading properties than our own muscle, bone and sinew; there would be awful failure mechanisms when it comes to a large transverse strain from a poor landing. Heck, when doing drop testing one of the first things that fail are any cheaply made nuts and bolts that shear off.

Stress failures of nuts and bolts is a little too much realism for a real robot show for me, so I'll just pretend they developed super titanium screws and rivets so the whole thing doesn't fall apart

[Seto Kaiba]

Stress failures of nuts and bolts is a little too much realism for a real robot show for me, so I'll just pretend they developed super titanium screws and rivets so the whole thing doesn't fall apart

... you say that in jest, but I can point to at least one tech manual that not only talks about it but goes into detail about how.

[MythSearcher]

Not necessarily. Yes if we treat it as a simple physics problem and the forces are roughly equal going up and going down but that's assuming a perfect landing. Just like humans we can jump and land no problem, but it's a different story if you screw up the landing and roll your ankle.

Then we have to take into account that a MS components are primarily metal which have way different ductility and loading properties than our own muscle, bone and sinew; there would be awful failure mechanisms when it comes to a large transverse strain from a poor landing. Heck, when doing drop testing one of the first things that fail are any cheaply made nuts and bolts that shear off.

Stress failures of nuts and bolts is a little too much realism for a real robot show for me, so I'll just pretend they developed super titanium screws and rivets so the whole thing doesn't fall apart :D

Well, considering they already did all the testing and have very high accuracy in AMBAC and immediate response in the force needed for a MS to even pick up a cow or a (larger than human size) wine glass, I'd say even if they did not perfected the computer program to do so, they are at least capable of making the program to be able to time the landing right in real time.
Considering the drag of a humanoid with human density is great(understatement) the landing should have less speed than the jump.

The only problem is that they do not have the required power output to jump to begin with. (Then again, this always loops back to the stated output aren't their maximum output and Rapport Deluxe surely list a much higher output in 5 digit HP compared to the 3~4 digit kW number we see)

[Seto Kaiba]

The only problem is that they do not have the required power output to jump to begin with. (Then again, this always loops back to the stated output aren't their maximum output and Rapport Deluxe surely list a much higher output in 5 digit HP compared to the 3~4 digit kW number we see)

More that it loops back to the problem that the stated output is the output of the generator after powertrain losses, not the reactor.

[MythSearcher]

More that it loops back to the problem that the stated output is the output of the generator after powertrain losses, not the reactor.

It obviously required much more power for all the systems, the thrust required something at least 10 times that output if the MS wanted to have at least reasonable operational time with the limited propellant they carry.
Moving the motors and servos will also require much more power to jump. (Or the initial velocity will be a pathetic one digit even if it has 100% efficiency, the Zaku, for example, has a maximum of ~5m/s standing up speed if we plug in 976kJ=0.5(74500kg)v^2, okay, some part of the leg's CoM is moving slower but you still need about 2s to stand up, nvm jumping)
Aiming with the weapons that will ikely weight in 5~10t range will be slow.
The heat hawk of the 06FZ also shouldn't be able to melt through that much material in such a short time if that is the only energy source. Granted, it can use capacitors, but still, the heat loss per m^2 already passed 100kW in the 1000 degrees C range, and we are talking about tens of thousands of degrees here. (https://www.engineeringtoolbox.com/radi ... d_431.html) Not to mention this is only radiation transfer, with air around, there's convection as well.
In fact, if it is as depicted in 0080, the outside armour of the MS gets to around 200 degrees in just 10 mins of operation by waste heat, just the waste heat should well be over 1000kW (consider there will be about 100~200 m^2 on the surface), and the M&Y generator was supposed to be highly efficient.

[Underrated GM Custom]

... you say that in jest, but I can point to at least one tech manual that not only talks about it but goes into detail about how.

Haha! I actually would really enjoy reading that if you don't mind sharing.

Considering the drag of a humanoid with human density is great(understatement) the landing should have less speed than the jump.

I mean yes, it's science fiction and we can hand-wave away that AMBAC solves all the problems. Can this well designed machine stick the landing without having their legs and fasteners explode outwards like a kid dropping their gunpla in the store? Yes, of course, there's no need to suspend disbelief there.

Picking up cows and wine glasses is all fine and dandy, but it doesn't account for the forces outside your sphere of influence. These walking war machines will get forced down not of their own volition, because of enemy fire, because the terrain crumbled under their weight, or because you said Kamille is a girl's name and now the building has a Gundam shaped hole in it. Falls like that could cause some severe internal damage in the same way that having a car travelling 60mph is no problem when it' s moving forward, but when it's travelling 60mph laterally it might destroy a lot of internal components that were designed with the intent of it going forwards and not sideways against it's will.

All I'm saying is that it's not as simple as a machine can jump therefore it can land without issue. Surely you agree that collision engineering is more sophisticated problem than speed up versus speed down?

[MythSearcher]

I mean yes, it's science fiction and we can hand-wave away that AMBAC solves all the problems. Can this well designed machine stick the landing without having their legs and fasteners explode outwards like a kid dropping their gunpla in the store? Yes, of course, there's no need to suspend disbelief there.

Picking up cows and wine glasses is all fine and dandy, but it doesn't account for the forces outside your sphere of influence. These walking war machines will get forced down not of their own volition, because of enemy fire, because the terrain crumbled under their weight, or because you said Kamille is a girl's name and now the building has a Gundam shaped hole in it. Falls like that could cause some severe internal damage in the same way that having a car travelling 60mph is no problem when it' s moving forward, but when it's travelling 60mph laterally it might destroy a lot of internal components that were designed with the intent of it going forwards and not sideways against it's will.

All I'm saying is that it's not as simple as a machine can jump therefore it can land without issue. Surely you agree that collision engineering is more sophisticated problem than speed up versus speed down?

Yes, I agree it is an issue, it's just that they have at least build in enough lore so that we know that at least in a regular, non-combat situation, they should be able to take it.
I mean, if you take into account accidents, cars really cannot survive heading 60km/h straight into a concrete wall of a normal building(the people inside might, but the car itself is highly unlikely) same thing for MS, which is why I like how they depict the jumps in 08th where they do it in caution, making sure they have enough propellant to do so(because if they don't, it will definitely be a crash land)

[Underrated GM Custom]

Yes, I agree it is an issue, it's just that they have at least build in enough lore so that we know that at least in a regular, non-combat situation, they should be able to take it.
I mean, if you take into account accidents, cars really cannot survive heading 60km/h straight into a concrete wall of a normal building(the people inside might, but the car itself is highly unlikely) same thing for MS, which is why I like how they depict the jumps in 08th where they do it in caution, making sure they have enough propellant to do so(because if they don't, it will definitely be a crash land)

Oh agreed, in universe I do think the legs can take it but I also think they have some massive dampeners in their legs otherwise the vibration mechanics up and down the legs would have an awful deleterious effect on all their fasteners. Those poor deck mechanics. While I love the skipping jumps in 0083 I think the hesitation in 08th is the most realistic portrayal of launching a 60+ ton machine through the air and hoping it can still walk afterwards.

My point about the car was that they're designed to go forward, but if they were to suddenly go sideways at the same speed a lot of internal components would have a shear failures. Can you design around that? Absolutely, as long as you don't break the limits of materials science you can over-engineer that car to move in a way it's not supposed to and be just fine.

Now let's consider that from a Gundam perspective and an engineering economics perspective. Let's say in-universe materials science would allow for a MS to take that sudden transverse force and it's internals don't snap in half but in doing so would require a considerable cost increase. Would it be worthwhile to design around having locomotion casualties?

Hard question to answer without knowing costs of course. If this engineering change would require a 5x increase to the Zaku II's cost, most likely not. But what if it was a 2x increase? Is it a worthwhile cost to have a MS can that be knocked to the ground after a catastrophic landing then get back up, or is it better to have twice as many suits. Tough question eh?