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This topic has moved here: Subject: Physics of a SPARTAN
  • Subject: Physics of a SPARTAN
Subject: Physics of a SPARTAN

I'm writing a Halo story involving a second (well if you count the SPARTAN-IIIs, third) group of SPARTAN super soldiers. I'm doing by best to adhere to realistic physics and maintain some form of coherency between my story and actual Halo cannon.

Anywho, the super soldiers, equipped with an armor made of a new metal, are attempting atmospheric insertion to land on Reach. They are dropping from the thermosphere (approx. 650 km) and utilizing the bullet form as they drop.

They armor they are wearing is lighter than standard MJOLNIR. I'm estimating around 800 lb instead of the usual half ton. I need to know the terminal velocity of said SPARTAN (I'm going to use it as an average).

I'm asking so I can determine an approximate time frame between touch down and drop. At some point a chute is going to deploy and slow them down so that they are not hitting the ground at terminal velocity. I'm skeptical that even with armor lock, it'd be an event they could live through. That in mind, can anyone suggest a realistic elevation that the chute should activate?

Thanks for the help.

  • 08.14.2012 7:09 PM PDT

Second group of Spartans? Are they Spartan IIIs?

Anyways, I'm not really sure about the physics. But a parachute wouldn't be able to support that much weight I think.

Why not use ODSTs drop pods? Spartans have been known to use them.

  • 08.14.2012 7:42 PM PDT

No, they're original. It's called the OMICRON Program. And Halsey was theorizing it (atmospheric insertion) for MJOLNIR Mk. VII. A chute with strong enough cables can do it. As for not using ODST pods, it defeat the purpose of the scene.

If you want to read what I've got you can check it out here:
http://forums.spacebattles.com/threads/halo-omicron.229107/#p ost-8228193

[Edited on 08.14.2012 7:49 PM PDT]

  • 08.14.2012 7:48 PM PDT
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  • Honorable Member


Posted by: IchinaruUzumaki

http://forums.spacebattles.com/threads/halo-omicron.229107/#p ost-8228193

  • 08.14.2012 7:52 PM PDT

This is the way the world ends,
This is the way the world ends,
This is the way the world ends;
Not with a bang but a whimper.

It depends how BA you want your Spartans to seem. Minimum distance to deploy a chute and still have enough elevation to deploy a reserve should the primary fail is 1500ft (~460m) AGL but it only takes 300ft (~90m) AGL for fulpounds to kilogramsl chute deployment. Keep in mind that lowest allowed altitude for a combat jump is 800ft (~240m) AGL.Note that most Halo (High Altitude Low Opening) jumps occur between 2000 and 3000ft (~600-910m) AGL. If your Spartans are only weighing about 1000lbs (assuming light armor) I would go with a chute deployment of between 1000 and 2000ft (~300-600m) AGL. It'd make them seem awesome without making them seem suicidal. But it is, of course, your decision to make.

Your terminal velocity question is rather more difficult. I have to make a number of assumptions:
Assumption 1: Each Spartan weighs 200lbs with the suit weighing 800lbs. This makes the average density roughly 5000kg/m^3.
Assumption 2: The Spartans are 0.5m (~20in) broad and 2m (~7ft) tall.
Assumption 3: The Spartans are diving at a steep 60 degree angle, yielding a cross-sectional area of about 0.5m^2.
Assumption 4: The drag coefficient of a Spartan is 1.0 (don't ask for units).
Assumption 5: Reach is a 1G planet.

Each of these assumptions are within reason, although they are still assumptions. Unless your reader is a physicist, they should not be able to tell the difference.

In any case, your answer is: 108 m/s for their terminal velocity. That said, they would accelerate from about 650km until around 100km, assuming Earth-like conditions. So terminal velocity does not matter until hitting around 100km because of a lack of atmosphere. Sadly, I was too lazy to bust out the calculus, so I made an estimate for the density of air. vT would be higher at greater elevations. It should still be a decent estimate provided you do not go above 100km in your calculations.

This is all using the formula vT=sqrt[(2mg)/(pACd) where m is mass, g is force of gravity, p is density of fluid, A is applicable area, and Cd is drag coefficient. I hope this helps somewhat. Keep in mind, the number could be totally wrong, so I take no responsibility if some PhD reads your work and slams you for it.

EDIT- Given terminal velocity of a skydiving human is about 55m/s. Considering that sqrt(5)=2.2, I am somewhat more confident in the veracity of my answer.

EDIT 2- I felt bad about leaving your question vauge. vT at sea level=108m/s. vT at 50km=3770m/s. vT at 100km=119,350m/s. If your spartans are reaching a thirtiet of the speed of light, you have an issue. So start your calculations at 50km up. I'll be back with a calculus answer ASAP.

[Edited on 08.14.2012 8:20 PM PDT]

  • 08.14.2012 8:10 PM PDT

Thank you so much! I tried finding the numbers and placing them in the equation myself, but got nowhere. I wasn't able to really proceed with my writing until I'd figured this out. This is a tremendous help!

On the chutes, I was wondering if it'd be possible for a SPARTAN to survive falling from that distance and impacting the ground at terminal velocity (with armor lock of course). I've got this scene in my head when the SPARTAN impacts and, shrugging off the collision with armor lock, jumps up and waylay's the Covenant surrounding her.

Is that at all feasible?

  • 08.14.2012 8:19 PM PDT

Don't you have to hit the ground when activating armour lock? I don't know.

Also, what triggers the locking mechanism of armour? I'm not talking about the AA, I'm talking about what Chief's suit did in Halo 3. It locked up.

  • 08.14.2012 8:28 PM PDT

This is the way the world ends,
This is the way the world ends,
This is the way the world ends;
Not with a bang but a whimper.

Posted by: IchinaruUzumaki
Thank you so much! I tried finding the numbers and placing them in the equation myself, but got nowhere. I wasn't able to really proceed with my writing until I'd figured this out. This is a tremendous help!

On the chutes, I was wondering if it'd be possible for a SPARTAN to survive falling from that distance and impacting the ground at terminal velocity (with armor lock of course). I've got this scene in my head when the SPARTAN impacts and, shrugging off the collision with armor lock, jumps up and waylay's the Covenant surrounding her.

Is that at all feasible?
Hold up for the time frame. I'm gonna stop being lazy and try to solve it with Calc, giving you a better timeframe than using the 108m/s, which is only accurate at sea level. See my second edit.

As for impacting the ground, a 363kg Spartan moving at 110m/s has over 2 million Joules of energy (using KE=.5mv^2). That is about the energy of 10 standard WWII grenades exploding all at once. Your call. Could your spartans lay on 15 grenades and survive? (15, not ten, because much of the energy from the explosion would disipate into the ground and atmopshere whereas the Spartan's impact energy would be mostly hitting him).

  • 08.14.2012 8:28 PM PDT

Armor lock can tank rockets and wraith blasts. I'm assuming 15 grenades shouldn't be an issue, right?

  • 08.14.2012 8:56 PM PDT

"I may not be perfect, but always been true."


Posted by: IchinaruUzumaki
Armor lock can tank rockets and wraith blasts. I'm assuming 15 grenades shouldn't be an issue, right?


Game Mechanics =/= reality.

  • 08.14.2012 9:01 PM PDT

This is the way the world ends,
This is the way the world ends,
This is the way the world ends;
Not with a bang but a whimper.

Posted by: RKOSNAKE
Game Mechanics =/= reality.
This. Up until Reach, armor lock didn't exist.

  • 08.14.2012 9:14 PM PDT

This is the way the world ends,
This is the way the world ends,
This is the way the world ends;
Not with a bang but a whimper.

Okay. I hit a major speed bump on the vT problem. It's a multivariable calc problem. I called up two of my buddies, and when we still could not figure it out, I gave up. If you're willing to use a semi-realistic number for velocity, I'd stick with 108m/s for 0-25km and 3500 for 25-50. After that, ignore air resistance. I'll ask my prof when I get to college, but that won't be for another two weeks.

  • 08.14.2012 9:22 PM PDT

This is the way the world ends,
This is the way the world ends,
This is the way the world ends;
Not with a bang but a whimper.

Posted by: May from Pokemon
My first post ever and it's in this thread sheesh!!
Care to help with multivariable calc?

  • 08.14.2012 10:52 PM PDT