EVE General Discussion

The Doppler effect as many of you know is a physics phenomenon where the perceived frequency of a traveling wave can be different depending on the relative velocity of the wave source and observer. It's what causes approaching police sirens to have a higher pitch which switches to a lower pitch when they pass you, and what causes astronomical objects to appear blue when approaching at high speeds or red when receding at high speeds.

I was in help chat one day answering questions when it occurred to me that missile damage is in fact a kind of wave, where pulses of damage (the missiles) travel through a certain distance at a finite velocity to reach a target. These pulses are emitted at a fixed frequency, but the distance between the attacking ship and the target is not fixed. If missile DPS exhibits a Doppler effect, missile DPS should be higher when the radial velocity between the two ships is negative (distance is decreasing), and lower when the radial velocity is positive (distance is increasing).

Let's take a 100MN HM Tengu, for example. I'll just use simplistic numbers here, instead of more exact values you'd find in EFT, to simplify calculation. We assume that missiles instantly reach their maximum speed just after being launched.

This particular ship is capable of flying at 2000 m/s, and does 500 DPS nominally (4 second rate of fire, 2000 alpha). The missiles travel at 8000 m/s, and we'll assume for simplicity's sake that they have infinite flight time. We'll also assume the target ship sits perfectly still. With the Tengu also sitting still, the target receives 500 DPS as you would expect (before resists and signature radius).

Things however appear to be different when motion is taken into account. Now we'll assume the Tengu is flying away from the target with a radial velocity of 2000 m/s. The formula for the observed frequency of a wave when the relative velocity of the observer and the emitter is not constant is f (observed) = (1 - v relative / v wave)*f (emitted). v relative is in this case the radial velocity. For the ships flying apart at 2000 m/s, the impact rate of the missiles is (1 - 2000/8000) * 1/4 = 3/16, or roughly 1 impact every 5.3333 seconds. With 2000 damage per hit, this causes an effective 375 DPS compared to the nominal 500. Seems pretty significant.

Now let's observe the case where the ships are flying closer with a radial velocity of 2000 m/s. The formula is f_0 = (1 + 2000/8000) * 1/4 = (1 + 1/4) * 1/4 = 5/16, or one impact every 3.2 seconds. 2000 damage / 3.2 seconds gives an effective DPS of 625. You've gained 125 DPS simply because you were flying straight at your target.


So my question to you is, do you believe missile DPS in EVE exhibits a Doppler effect, and have you ever noticed it?

As I'm pretty sure they only use base ship velocity when calculating explosion velocity. I don't believe it as I have not noticed it.

Congrats on attending maths classes in highschool.
Realistically the distances traveled between missile volleys is going to be insignificant for this affect but yes, you are correct.

So... make a cruise raven that can fly the speed of it's own cruise missiles. Start burning toward the enemy from 250km away while shooting missiles. Alpha anything?

Never noticed it, probably it's too much work for hamsters.

If missiles travel the same speed throughout flight, then if a ship is traveling towards another ship, the missiles should increase in the frequency of impact. I don't use missiles, but I have no reason to assume this isn't true based on knowing that missiles have a finite flight time (as opposed to instant like guns), and ship velocity changes the point of origin of the missile being launched...

That actually has nothing to do with what I said.

The damage per volley doesn't change, I'm talking about the damage per second, which changes depending on both the damage per volley and the volleys per second that hit the target. For turrets the velocity is effectively instantaneous, so the impacts per second will be the same as the rate of fire of the weapon, however that's not true for missiles because when you're flying a missile ship towards its target each successive missile doesn't have to fly as far as the previous one and so reach their target more quickly, resulting in missiles hitting the target at a rate higher than the missiles are fired, which results in a higher rate of damage done to the target.

LOL congrats on skipping grammer.

This used to be my strategy with ICC torpedo cruisers in Darkspace.