Mobile Suit Delta V values

[Nebfer]

A while back their was some talk on what kind of endurance a mobile suit would have. While very little is given on how long a mobile suit can use it's engines, their are with a few assumptions enough info to get an idea how long a suit can operate (I would presume at max thrust) and how much Delta V it's thrust & propellant levels will generate.

Now the following info Assumes a ISP of 4,500, this is effectively ten times that of LH2 & LOX propellants used in real life (so divide these numbers by ten to see what a mobile suit will be capable of in real life), also many suits do not provide a brake down of weapons and propellant ratios, though their is enough to assume that most of though that do not have a some what similar ratio(s).
Nor I would class this as 100% accurate in any case, after all I have no idea what kind of ISP their engines use, this also uses a static value, it's not unlikely for their to be some variation between suits and time frames.
Also I have not done every suit nor do I intend to at this time (though I can do some requests, assuming the info is present).

Selected Suits from 0075 to 0083
Zaku I
Year........ 0075
Mass Full... 65,000
Mass Empty.. 50,300
Fuel Weight. 10,300 (1,139 Seconds worth at max thrust)
War load.... 5,000
Acell rate.. 0.63 (6.18m/s)
Thrust...... 40,700kgf
Mass Ratio..
Delta V..... 7.04km/s

Zaku II F
Year........ 0078 (late)
Mass Full... 73,300 kg
Mass Empty.. 58,100
Fuel Weight. 10,200kg (1,067 Seconds worth at max thrust)
War load.... 5,000
Acell rate.. 0.59Gs (5.79m/s)
Thrust...... 43,000 kgf
Mass Ratio..
Delta V..... 6.18km/s

Zaku II F2
Year........ 0079
Mass Full... 70,300
Mass Empty.. 49,900
Fuel Weight. 14,400 (1,213 seconds)
War load.... 6,000
Acell rate.. 0.76Gs (7.46m/s)
Thrust...... 53,400kgf
Mass Ratio..
Delta V..... 9.05km/s

Zaku II Fz "Kai"
Year........ 0079
Mass Full... 74,500
Mass Empty.. 56,200
Fuel Weight. 13,300 (753 seconds)
War load.... 5,000
Acell rate.. 1.07Gs (10.5m/s)
Thrust...... 79,500kgf
Mass Ratio..
Delta V..... 7.91km/s

Zaku II S
Year........ 0079
Mass Full... 75,200
Mass Empty.. 56,500
Fuel Weight. 13,700 (1,195 seconds)
War load.... 5,000
Acell rate.. 0.69Gs (6.77m/s)
Thrust...... 51,600 kgf
Mass Ratio..
Delta V..... 8.09 km/s

Zaku II R1A
Year........ 0079
Mass Full... 76,800
Mass Empty.. 61,800
Fuel Weight. 10,000 (865 seconds)
War load.... 5,000
Acell rate.. 0.68Gs (6.67m/s)
Thrust...... 52,000kgf
Mass Ratio..
Delta V..... 5.77km/s

Rickdom
Year........ 0079
Mass Full... 78,600
Mass Empty.. 43,800
Fuel Weight. 27,800 (2,360 seconds)
War load.... 7,000
Acell rate.. 0.67Gs (6.58m/s)
Thrust...... 53,000kgf
Mass Ratio..
Delta V..... 15.53km/s

Rickdom 2
Year........ 0079
Mass Full... 79,900
Mass Empty.. 45,600
Fuel Weight. 27,300 (2,194, 1,117 seconds)
War load.... 7,000
Acell rate.. 0.7Gs (6.87m/s) 1.38Gs (13.54m/s)
Thrust...... 56,000kgf (110,000kgf)
Mass Ratio..
Delta V..... 15.07km/s (15.13km/s)
The second set is for the 0080 numbers

Gelgoog (A)
Year........ 0079
Mass Full... 73,300
Mass Empty.. 42,100
Fuel Weight. 26,200 (1,917)
War load.... 5,000
Acell rate.. 0.84Gs (8.24m/s)
Thrust...... 61,500 kgf
Mass Ratio.. NA
Delta V..... 15.8km/s

Gelgoog Marine
Year........ 0079
Mass Full... 81,300
Mass Empty.. 45,100
Fuel Weight. 30,200 (2,471)
War load.... 6,000
Acell rate.. 0.68Gs (6.67m/s)
Thrust...... 55,000kgf
Mass Ratio..
Delta V..... 16.48km/s

----Federation----

GM
Year........ 0079
Mass Full... 58,800kg
Mass Empty.. 41,200kg
Fuel Weight. 12,600kg (1022 seconds)
War load.... 5,000kg (Asumed)
Acell rate.. 0.94Gs (9.23m/s)
Thrust...... 55,480kgf
Mass Ratio.. NA
Delta V..... 9.43km/s

GM Command Space type
Year........ 0079
Mass Full... 76,500kg
Mass Empty.. 44,600kg
Fuel Weight. 25,900kg (1,575 seconds)
War load.... 6,000kg
Acell rate.. 0.97Gs (9.52m/s)
Thrust...... 74,000kgf
Mass Ratio.. NA
Delta V..... 15km/s

GM C "Kai"
Year........ 0079
Mass Full... 58,800
Mass Empty.. 41,200
Fuel Weight. 12,600 (987 seconds)
War load.... 5,000
Acell rate.. 0.98Gs (9.62m/s)
Thrust...... 57,480kgf
Mass Ratio..
Delta V..... 9.5km/s

Guncannon Mass produced type
Year........ 0079
Mass Full... 70,200
Mass Empty.. 51,000
Fuel Weight. 10,000 (481 seconds)
War load.... 9,000
Acell rate.. 1.33Gs (13.05m/s)
Thrust...... 93,500kgf
Mass Ratio..
Delta V..... 6.28km/s

Gundam -2
Year........ 0079
Mass Full... 60,000kg
Mass Empty.. 43,400kg
Fuel Weight. 6,000
War load.... 10,600 (860 seconds)
Acell rate.. 0.93Gs (9.13m/s)
Thrust...... 55,480kgf
Mass Ratio..
Delta V..... 7.85km/s

Ball
Year........ 0079
Mass Full... 25,000
Mass Empty.. 17,200
Fuel Weight. 5,000 (938 seconds)
War load.... 2,800
Acell rate.. 0.96Gs (9.4m/s)
Thrust...... 24,000kg
Mass Ratio..
Delta V..... 8.89km/s


I'll post up the Zeta Era suits in a bit.
Any corrections, or suits one would like to see?

[toysdream]

Seems about in the right ballpark. Technically, the only factors that affect the delta-V calculation are the mass ratio and the specific impulse, so if we know (or can guess) the former, then the only question is the latter figure.

-- Mark

[Nebfer]

As promised Selected suits from the Zeta and Double Zeta era and the UC 90s

GM II
EFF
Year........ 0080
Mass Full... 58,700kg
Mass Empty.. 40,500kg
Fuel Weight. 13,200kg (958 seconds)
War load.... 5,000kg
Acell rate.. 1.06Gs (10.4m/s)
Thrust...... 62,000kgf
Mass Ratio.. 1.29
Delta V..... 9.96km/s

GM III
EFF
Year........ 0088
Mass Full... 56,200kg
Mass Empty.. 38,600kg
Fuel Weight. 12,600kg (698 seconds)
War load.... 5,000kg
Acell rate.. 1.45Gs (14.23m/s)
Thrust...... 81,200kgf
Mass Ratio.. 1.29
Delta V..... 9.94km/s

GM III Nouvel
EFF
Year........ 0088
Mass Full... 68,200kg
Mass Empty.. 42,300kg
Fuel Weight. 20,900kg (1,158 seconds)
War load.... 5,000kg
Acell rate.. 1.19Gs (11.68m/s)
Thrust...... 81,200kgf
Mass Ratio.. 1.29
Delta V..... 13.53km/s

Nemo
AEUG
Year........ 0087
Mass Full... 55,600kg
Mass Empty.. 36,200kg
Fuel Weight. 13,500 (949 seconds)
War load.... 5,900
Acell rate.. 1.15Gs (11.28m/s)
Thrust...... 64,000kgf
Mass Ratio.. 1.32
Delta V..... 10.71km/s

Hi-Zack
EFF
Year........ 0084
Mass Full... 59,600
Mass Empty.. 38,700
Fuel Weight. 14,900 (1,035 seconds)
War load.... 6,000
Acell rate.. 1.09Gs (10.7m/s)
Thrust...... 64,800kgf
Mass Ratio.. 1.33
Delta V..... 11.08km/s

Galbaldy beta
EFF
Year........ 0084
Mass Full... 56,900
Mass Empty.. 36,300
Fuel Weight. 14,600 (1,040 seconds)
War load.... 6,000
Acell rate.. 1.11Gs (10.9m/s)
Thrust...... 63,200kgf
Mass Ratio.. 1.35
Delta V..... 11.34km/s

Gundam Mk II
Titans/AEUG
Year........ 0086
Mass Full... 54,100
Mass Empty.. 33,400
Fuel Weight. 16,500 (914 seconds)
War load.... 7,000
Acell rate.. 1.5Gs (14.72m/s)
Thrust...... 81,200 kgf
Mass Ratio..
Delta V..... 13.45km/s

Zeta Gundam
AEUG
Year........ 0087
Mass Full... 62,300
Mass Empty.. 28,700
Fuel Weight. 25,600 (1,023 seconds)
War load.... 8,000
Acell rate.. 1.81Gs (17.75m/s)
Thrust...... 112,600 kgf
Mass Ratio.. 1.7
Delta V..... 18.16km/s

Rick Dias
AEUG
Year........ 0086
Mass Full... 54,700
Mass Empty.. 32,200
Fuel Weight. 16,500 (993 seconds)
War load.... 6,000
Acell rate.. 1.37Gs (13.44m/s)
Thrust...... 74,800 kgf
Mass Ratio.. 1.43
Delta V..... 13.35km/s

Marasai
Titans
Year........ 0086
Mass Full... 59,400
Mass Empty.. 33,100
Fuel Weight. 19,300 (1,164 seconds)
War load.... 7,000
Acell rate.. 1.26Gs (12.37m/s)
Thrust...... 74,600 kgf
Mass Ratio.. 1.48
Delta V..... 14.4km/s

Gaza D
Zeon
Year........ 0088
Mass Full... 68,400
Mass Empty.. 28,700
Fuel Weight. 31,700 (1,453 seconds)
War load.... 8,000
Acell rate.. 1.44Gs (14.13m/s)
Thrust...... 98,200kgf
Mass Ratio.. 1.86
Delta V..... 20.53km/s

The O
Titans
Year........ 0087
Mass Full... 86,300
Mass Empty.. 57,300
Fuel Weight. 23,000 (765 seconds)
War load.... 6,000
Acell rate.. 1.57Gs (15.41m/s)
Thrust...... 135,400kgf
Mass Ratio.. 1.36
Delta V..... 11.79km/s

Zaku III
Zeon
Year........ 0088
Mass Full... 68,300
Mass Empty.. 44,200
Fuel Weight. 18,100 (472 seconds)
War load.... 6000
Acell rate.. 2.53Gs (24.82m/s)
Thrust...... 172,600
Mass Ratio.. 1.36
Delta V..... 11.72km/s

Doven Wolf
Zeon
0087
Fuel Weight 29.7 tons
Delta V 17.57 km/s

The vastly higher Delta V / Endurance of the Doven Wolf likely indicating part of why the Zaku III was not chosen for mass production

---- UC 90 era----
Jegan
Year........ 0089
Mass Full... 47,300
Mass Empty.. 21,300
Fuel Weight. 20,000 (1,848 seconds)
War load.... 6,000
Acell rate.. 1.03Gs (10.1m/s)
Thrust...... 48,700kgf
Mass Ratio.. NA
Delta V..... 18.67km/s

Jegan D
Year........ 0094
Mass Full... 47,300
Mass Empty.. 21,300
Fuel Weight. 20,000 (1,452)
War load.... 6,000
Acell rate.. 1.31Gs (12.85m/s)
Thrust...... 62,000kgf
Mass Ratio.. NA
Delta V..... 18.66km/s

Jegan Stark
Year........ 0096
Mass Full... 61,800
Mass Empty.. 28,400
Fuel Weight. 26,400 (1,551)
War load.... 7,000
Acell rate.. 1.24Gs (12.17m/s)
Thrust...... 76,600kgf
Mass Ratio.. NA
Delta V..... 18.88km/s

Geara Zulu
Year........ 0096
Mass Full... 55,200
Mass Empty.. 21,800
Fuel Weight. 27,400 (1,986)
War load.... 6,000
Acell rate.. 1.13Gs (11m/s)
Thrust...... 62,100kgf
Mass Ratio..
Delta V..... 21.85km/s

Geara Doga
Year........ 0090
Mass Full... 50,800
Mass Empty.. 23,000
Fuel Weight. 21,800 (1,817)
War load.... 6,000
Acell rate.. 1.06Gs (10.4m/s)
Thrust...... 54,000kgf
Mass Ratio..
Delta V..... 18.9km/s

Edit: fixed Gundam Mk-IIs values

[toysdream]

Note that the Gundam Mark II has a mass ratio of 1.44, and thus a weapons payload of about 4.2 tons. (This is one of the very few cases where the mass ratio math doesn't yield a payload figure that's a round number of tons; the ZZ Gundam is another.)

Since the only variables in the delta-V equation are mass ratio and specific impulse, all these figures should be in correct proportion to each other, even if the actual numbers are off. This means that, if we knew the maximum delta-V or maximum thrust duration for even one of these machines, we could fill in all the rest. What a pity.

-- Mark

[Nebfer]

Note that the Gundam Mark II has a mass ratio of 1.44, and thus a weapons payload of about 4.2 tons. (This is one of the very few cases where the mass ratio math doesn't yield a payload figure that's a round number of tons; the ZZ Gundam is another.)

Since the only variables in the delta-V equation are mass ratio and specific impulse, all these figures should be in correct proportion to each other, even if the actual numbers are off. This means that, if we knew the maximum delta-V or maximum thrust duration for even one of these machines, we could fill in all the rest. What a pity.

-- Mark

Well the Wiki oddly dose not list the Ratio for the Mk II, and I managed not to check MAHQs entry. So I just assumed it had a slightly less payload than it's successor...

Though doing the math with the mass ratios I often came up with not exact numbers, often something like 5,153 kg, I would assume they where often rounded...

Their seems to be some interesting trends the Zeon suits after the Zaku II went for massive fuel ratios and as one can see often have noticeably higher velocity values than their federation counter parts. Though the Federation seems to get the idea with the Jegan...

The Zaku II R1A is interesting, it's really let down by it's low propellant capacity and higher thrust engines, resulting in the worst values of the suits I used.

The GM Command is a bit surprising as is the Gelgoogs and Rickdoms, with quite the Delta V values for their time frame... Though the 0080 suits I believe are a bit out of spec compared to their counter parts...

[toysdream]

In a lot of cases, a straight division by the mass ratio yields a figure like 6.1 or 5.9 tons, but if you try it with 6.0 tons the mass ratio comes out the same (thanks to the magic of rounding to two digits). There are only about 3-4 cases in all of Zeta and ZZ where you can't get the listed mass ratio value using a round number of tons, and the Mark II happens to be one of them.

A lot of the One Year War Zeon mobile suit specs are nonsensical, and they get retconned back and forth all the time. On the whole, I think these are bad examples to look at. Probably we can assume the vintage mobile suit specs from ZZ are accurate, but the older ones should be evaluated using the ZZ ones as a yardstick.

-- Mark

[Nebfer]

In a lot of cases, a straight division by the mass ratio yields a figure like 6.1 or 5.9 tons, but if you try it with 6.0 tons the mass ratio comes out the same (thanks to the magic of rounding to two digits). There are only about 3-4 cases in all of Zeta and ZZ where you can't get the listed mass ratio value using a round number of tons, and the Mark II happens to be one of them.

A lot of the One Year War Zeon mobile suit specs are nonsensical, and they get retconned back and forth all the time. On the whole, I think these are bad examples to look at. Probably we can assume the vintage mobile suit specs from ZZ are accurate, but the older ones should be evaluated using the ZZ ones as a yardstick.

-- Mark

In what way? Lighter base weights?, fuel fractions? Thrust (an obvious one)?
I would think that suits built to take ballistic weapons should be notably heavier than ones built later on... I think 50-60 tons is fine for OYW era suits, 30-50 tons for the late 80s. At 20 tons I think its cutting it a bit thin particularly if one wants to have any armor to speak of...

[toysdream]

The ZZ machines have lighter base weights, which seems reasonable enough given new materials and replacement generators. But we should be able to compare their propellant supplies to those of earlier models. The Dowadge and ReGelgu, for instance, have a bunch of extra propellant tanks that aren't installed on previous machines so you'd expect them to have more propellant. The fact that the ReGelgu has 34.9 tons of propellant, and its backpack is similar to that of the Gelgoog Marine but with a bigger built-in tank and a couple of huge extra ones tacked on as well, seems like reason enough to question the Marine's specs.

-- Mark

[Brave Fencer Kirby]

What made you pick 4,500 as your specific impulse? One of the major advantages of Gundam tech over current real-world rocket science is the fact that they're able to use nuclear fusion reactors to power their thrusters -- which have Isp waaaaay more than 10 times that of conventional chemical rockets.

For example, Atomic Rockets' entry on a helium-3 + deuterium fusion rocket. The listed exhaust velocity is 7,840,000 m/s, which makes the Isp just shy of 800,000 seconds. UC Gundam explicitly uses the He-3 + D reaction for its Minovsky reactors, but Atomic Rockets assumes hydrogen propellant, which may or may not be accurate for UC Gundam. (Hydrogen is the most efficient propellant you can use in terms of Isp, thanks to its low molecular weight, but it's a pain in the ass to store -- both because it's very low density and because it tends to "evaporate" through solid propellant tank walls, so it's likely that mobile suits use something else.) Using something like water for propellant would be less efficient (by about half, according to the NTR solid core entry), but even if we assume that UC mobile suit engines are 100 times less efficient than the theoretical Atomic Rockets value, that's still almost twice as efficient as the 4,500 number you're using. (For easy reference, here's a link to the Atomic Rockets hydrogen-oxygen chemical rocket entry.)

Edit -- also worth keeping in mind: those dV values seem on the high side for how we see mobile suits being used in the animation. In theory, getting from Earth's surface to low Earth orbit (LEO) takes 7.8 km/s of dV. (In reality, it's closer to 10 km/s, since you've got to punch through the atmosphere as well as reach 7.8 km/s orbital velocity. Also, your vehicle needs to have a thrust/weight ratio of greater than 1, which not all mobile suits do, but that's neither here nor there.) Given that we rarely-if-ever see mobile suits even travelling from place to place on their on in-orbit (eg, flying from one Lagrange point to another), much less blasting themselves into orbit from the ground, it's unlikely that they'd need that much dV.

On the flip side, dV budgets are assuming that you're doing one quick shot of thrust and then coasting the rest of the way to your destination, while mobile suits are accelerating near-constantly in combat, so maybe the values you've calculated aren't all that unreasonable. (Then again, it does make it harder to believe the repeated "whoops, we screwed up during a battle in LEO, now we're forced to go through atmospheric re-entry". So who knows?)

[toysdream]

What made you pick 4,500 as your specific impulse? One of the major advantages of Gundam tech over current real-world rocket science is the fact that they're able to use nuclear fusion reactors to power their thrusters -- which have Isp waaaaay more than 10 times that of conventional chemical rockets.

For example, Atomic Rockets' entry on a helium-3 + deuterium fusion rocket. The listed exhaust velocity is 7,840,000 m/s, which makes the Isp just shy of 800,000 seconds.

Different kind of engine. The figures you're citing are for a "leaky" fusion rocket, where the magnetic field that contains the reaction is opened at one end so that the actual reactants can whoosh out; mix in some extra bulk propellant, and you have a really hot exhaust stream with high velocity (and thus specific impulse) but pretty low thrust, plus a hole in your reactor.

The propulsion systems used in UC Gundam are nuclear thermal rockets, in which propellant is circulated around the reactor without actually going in, so that some of the reactor heat is transferred to the propellant. This is sometimes referred to as a "nuclear lightbulb," and the page you pointed to has sample values for some fission-based versions starting here: http://www.projectrho.com/public_html/r ... rsolidcore.

-- Mark

[Brave Fencer Kirby]

Huh, whoops. I guess I didn't scroll up far enough to see that the template they were using for fusion rockets was an open-cycle type. Mea culpa.

I'm not sure what would be the closest thing Atomic Rockets has to what Gundam uses, then. I'm tempted to say the closed-cycle gaseous nuclear thermal rocket, but given that specific impulse depends a lot on reactor temperature, which is in turn dependant on the type of nuclear reaction you're using, I'm skeptical of how well it would apply. Of course, we could split the difference and cherry pick the fact that a closed-type gas NTR has about half the exhaust velocity/dV of an open-type and apply it to the He-3 + D fusion engine stats (which would get us around 400k seconds Isp). Half that again for using a nice, dense propellant like water instead of hydrogen, and you've got 200,000 seconds Isp.

Also worth noting from the closed gas NTR entry: "The ideal solution would be to somehow constrain the uranium by something non-material, such as a mangnetohydrodynamic force field or something like that. Alas, currently such fields can only withstand pressures on the order of the breeze from a flapping mosquito, not the 500 atmospheres of pressure found here." This is, of course, the exact breakthrough (the use of an I-field to contain the fusion reaction) that allowed for the creation of the Minovsky reactor.

In any case, I'll have to look through Atomic Rockets a little more and see if I can find the raw formulas he's using. Maybe I'll be able to plug in the appropriate numbers to find a better value for a Gundam-style closed-cycle fusion rocket.

[Nebfer]

What made you pick 4,500 as your specific impulse? One of the major advantages of Gundam tech over current real-world rocket science is the fact that they're able to use nuclear fusion reactors to power their thrusters -- which have Isp waaaaay more than 10 times that of conventional chemical rockets.

Well because it's simply 10x what chemicals can get, also that it was not to far off from the quote of the Zaku II R1A value of 15 minutes fuel. Though that dose depend on what exact meaning of 15 minutes they are using? Combat only? (I.e. a few minutes at a unspecified power for travel to and from combat), total burn time at a specific rate... and so on... If one assumes that the value is total burn time at max thrust than you get a ISP of around 4700 to reach the required 15 minutes at the stated thrust.

It is also low enough to have impressive Delta V values and yet still have the notable limitations UC era mobile suits seem to have for much of it's history. I'll talk about this below...

For example, Atomic Rockets' entry on a helium-3 + deuterium fusion rocket. The listed exhaust velocity is 7,840,000 m/s, which makes the Isp just shy of 800,000 seconds. UC Gundam explicitly uses the He-3 + D reaction for its Minovsky reactors, but Atomic Rockets assumes hydrogen propellant, which may or may not be accurate for UC Gundam. (Hydrogen is the most efficient propellant you can use in terms of Isp, thanks to its low molecular weight, but it's a pain in the ass to store -- both because it's very low density and because it tends to "evaporate" through solid propellant tank walls, so it's likely that mobile suits use something else.) Using something like water for propellant would be less efficient (by about half, according to the NTR solid core entry), but even if we assume that UC mobile suit engines are 100 times less efficient than the theoretical Atomic Rockets value, that's still almost twice as efficient as the 4,500 number you're using. (For easy reference, here's a link to the Atomic Rockets hydrogen-oxygen chemical rocket entry.)

I know of that site, the shear numbers of different types kinda makes it hard for me to get it all in...
Though I doubt they use Fusion drives which is what your talking about their. And that kind of ISP in any case causes some issues which you mention later...

Edit -- also worth keeping in mind: those dV values seem on the high side for how we see mobile suits being used in the animation. In theory, getting from Earth's surface to low Earth orbit (LEO) takes 7.8 km/s of dV. (In reality, it's closer to 10 km/s, since you've got to punch through the atmosphere as well as reach 7.8 km/s orbital velocity. Also, your vehicle needs to have a thrust/weight ratio of greater than 1, which not all mobile suits do, but that's neither here nor there.) Given that we rarely-if-ever see mobile suits even travelling from place to place on their on in-orbit (eg, flying from one Lagrange point to another), much less blasting themselves into orbit from the ground, it's unlikely that they'd need that much dV.

On the flip side, dV budgets are assuming that you're doing one quick shot of thrust and then coasting the rest of the way to your destination, while mobile suits are accelerating near-constantly in combat, so maybe the values you've calculated aren't all that unreasonable. (Then again, it does make it harder to believe the repeated "whoops, we screwed up during a battle in LEO, now we're forced to go through atmospheric re-entry". So who knows?)

THe Delta V issue is also why I chose 4,500 for my ISP value, to As you said to escape earths Gravity requires 7.8km/s with an extra 2km/s often being added for "Rocket" drag issues, one could argue that a mobile suit would be much less aerodynamic than a rocket, but I doubt it would double it, but who knows... Even so we do know that a UC era Mobile suit rarely if ever single stages to orbit, and that operating near earths space to atmosphere interface is considered dangerous (in more than one way), as shown quite a few times. Never mind that we never see them go to the moon from earth orbit or other such place in a timely manor... So their Delta V is low enough for that to be a factor (I.e. 120km/s of Delta V will get you to the moon from earth orbit in 3.5 hours at 1G, so they clearly do not have that ability).

Huh, whoops. I guess I didn't scroll up far enough to see that the template they were using for fusion rockets was an open-cycle type. Mea culpa.

I'm not sure what would be the closest thing Atomic Rockets has to what Gundam uses, then. I'm tempted to say the closed-cycle gaseous nuclear thermal rocket, but given that specific impulse depends a lot on reactor temperature, which is in turn dependant on the type of nuclear reaction you're using, I'm skeptical of how well it would apply. Of course, we could split the difference and cherry pick the fact that a closed-type gas NTR has about half the exhaust velocity/dV of an open-type and apply it to the He-3 + D fusion engine stats (which would get us around 400k seconds Isp). Half that again for using a nice, dense propellant like water instead of hydrogen, and you've got 200,000 seconds Isp.

Also worth noting from the closed gas NTR entry: "The ideal solution would be to somehow constrain the uranium by something non-material, such as a mangnetohydrodynamic force field or something like that. Alas, currently such fields can only withstand pressures on the order of the breeze from a flapping mosquito, not the 500 atmospheres of pressure found here." This is, of course, the exact breakthrough (the use of an I-field to contain the fusion reaction) that allowed for the creation of the Minovsky reactor.

In any case, I'll have to look through Atomic Rockets a little more and see if I can find the raw formulas he's using. Maybe I'll be able to plug in the appropriate numbers to find a better value for a Gundam-style closed-cycle fusion rocket.

Well your free to figure out a better value, though I would suspect that it's not going to be significantly higher. After all even an ISP of 20,000 will result in more than a FOUR fold increase in delta V A Zaku I having 31km/s and a Geara Doga 84 km/s for example. At these values fighting in low earth orbit would be next to trivial and not risky, and these values I would think it would easy for a suit to single stage to orbit with ample fuel for combat, even if we assume more than a three fold increase in the actual value for drag reasons (I.e. say 25km/s required to reach orbit). Using the Geara Doga with the 84km/s DV It should have the capability of reaching the moon and returning back to it's starting location in earth orbit in roughly 24 hours with some fuel to spare. Which is not something any regular mobile suit seems to be capable of to my knowledge.

Never mind the fact that In unicorn we find that when Riddhe takes Mineva to earth from Palau which is located at the L5 point that the combat that he dose renders him incapable of reaching earth on his own IIRC. (By the way how long did it take him any way? IIRC I have been told it was like 2 days...).


Hold on I do seem recall that in cross born vanguard that theirs suits that can reach Jupiter in a week on their on or something like that? is this what later era UC suits and space craft can do?