Brief Notes On A High Energy Event
I have been interested in analyzing the Drebuchet technique in the context of EVE's motion model for some time. I was pleasantly surprised to find that the Rooks & Kings YouTube channel had a helpful clue along these lines. In this video, RnK explains how this technique works, and show some applications. The essential idea is to take advantage of a ship being ejected from a POS shield to bump ships with tremendous energy.My interest in analyzing the motion of ships in these conditions is that POS shield ejection represents a new physical interaction that is not yet modeled in my notes. I've modeled the effect of ships bumping ships, as well as ships bumping immovable objects, but what is the equivalent bump of changing a POS-shield password?
Normally, I would try to measure the energy of the POS shield by seeing how far ships are flung. What is their final resting distance from the starting position? While this might be easy to do conceptually, it is much easier if someone takes the data for me. Furthermore, the bump data from this video will provide a way to double-check any other measurements I make in the future.
On with the data -- The video below has a clue at the 5:28 mark that can help me to determine how much energy is in a POS shield ejection.
Is there anything more satisfying than a titan moving at 20km/s? A couple things to note about this. First, the narrator explains that the dreadnought is put in siege mode prior to ejection with the POS password change. This means that during the event, the mass of the bumping ship is +900% or 10x the nominal mass. Second, even though there is no explicit image showing the alignment of the bump dread and the titan target, I am going to assume alignment is perfect.
Is there anything more satisfying than a titan moving at 20km/s? A couple things to note about this. First, the narrator explains that the dreadnought is put in siege mode prior to ejection with the POS password change. This means that during the event, the mass of the bumping ship is +900% or 10x the nominal mass. Second, even though there is no explicit image showing the alignment of the bump dread and the titan target, I am going to assume alignment is perfect.
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| Figure 1: Thanks to the velocity overlay, the Avatar velocity can be read. It appears that the maximum is near 20km/s for this bump event! Furthermore, note they have used a Naglfar Dreadnought to bump this titan. |
You can see that the moment when the bump event occurs, where the Titan accelerates from stationary to 20km/s instantaneously. We know the mass of both objects and we know the velocity of the Titan immediately after the collision.
As a matter of perspective, the energy change required to accelerate a titan to 20,000m/s is approximately 2 x 1017 joules, which is a remarkable energy. Consider that the energy released by a one megaton nuclear weapon is approximately 4 x 1015 joules. So the POS shield energy delivers at least the energy of a 50 megaton warhead all to one object. That would be a lot of energy, but keep in mind that we are looking at the energy of only one of the two ships, and unless the mass of the bumping ship matches the mass of the target ship, there will be residual energy reflected in the bump ship as well.
Fortunately, we know the masses of the objects as well as one of the final velocities, leaving the velocity of the bumping ship before and after the bump event as unknowns. All collisions in EVE are elastic, so we also have two equations -- one for conservation of momentum and one for conservation of energy. I'm not including the equations here but you can review them in Part III of my notes or in the posts on bumping with mass-matching techniques.
Two Equations, Two Unknowns -- You Know What To Do
I solve for both the before bump and after bump velocities of the siege-mode dreadnought. I find the velocities before and after the bump, respectively,
$\Large v_1(0^-) = v_2 \frac{m_2 + m_1}{2m_1}$
$\Large v_1(0^+) = v_2 \frac{-m_2 + m_1}{2m_1}$
$\Large v_1(0^+) = v_2 \frac{-m_2 + m_1}{2m_1}$
I'll assume that the Dreadnought is in siege resulting in the masses as follows:
- m1 = mSiegeNaglfar = 1.1 x 1010 kg
- m2 = mAvatar = 2.2 x 109 kg
The velocity of the bump ship before and after the bump are,
- v1(0-) = 12000 m/s
- v1(0+) = 8000 m/s
Prior to striking the titan, all of the energy is in the Naglfar, meaning that we can revise our calculation of the total POS shield energy from the motion of the one ship at that time, prior to the collision. I find the total energy is 8 x 1017 joules, equivalent to a blast from 200 megaton warhead.
Putting this in the context of being bumped by other ships, it would take all of the energy from over 700 thousand 500MN stabbers to deliver this much energy in a single bump, which isn't even realistic.
If you left the titan to drift to a stop, it would come to a rest at τVMAX = 81.4s x 20,000m/s = 1,600km. Because a siege-mode Dreadnought has 10x the time-constant as non-siege-mode, the bump distance should be almost 6000km. Indeed, the POS password is mightier than the sword.
If you left the titan to drift to a stop, it would come to a rest at τVMAX = 81.4s x 20,000m/s = 1,600km. Because a siege-mode Dreadnought has 10x the time-constant as non-siege-mode, the bump distance should be almost 6000km. Indeed, the POS password is mightier than the sword.
Always More Questions
You can have a lot of ships inside a POS shield. Do they all get the same energy? Or is there an equivalent bump mass that the POS shield delivers to the ships. Like characterizing matter with high energy particle collisions, the POS shield could be characterized by looking at the resting distance of launching ships with a spectrum of masses.
Acknowledgement
Thank you to Rooks and Kings for posting their technique with quantitative information, making it possible for EVE physics to move forward.
