Thursday, March 5, 2015

Fingerbob's guide to Elite Dangerous Trading, Part Three and a bit

Hi! I was expecting my next post to be about trading in the larger ships, but I thought it would be worth sharing a few of the observations I've made from running the rare trade routes in my Cobra and my Type 6.

The first question I've been looking to answer is, "should I jump to maximum range and scoop, or should I use an efficient jump route?" - and I've got a definitive answer, at least for one set of upgrades.

The second question I've been looking to answer is, "How much fuel do I use to jump?" - and I've got a definitive answer for that, too.

Read on for more detail!

Jump to max range and scoop, or jump efficiently?

When you plan a route in the galactic map, you've got to make a decision between "Economical Routes" or "Fastest Routes".

The key difference is the amount of fuel you use overall and how far each jump will be.

When you select "Economical Routes" your planned route will take many short jumps as close to a straight line as possible - but it will aim to minimize the amount of fuel you use, so the route travelled may be quite winding and will likely have jumps that you don't expect to make if you draw a straight line between your starting point and your destination.

When you select "Fastest Routes" your planned route will aim to jump as far as possible based on your current max jump range, as long as you're heading in the correct direction. This route will have fewer jumps.

You'd expect that this would use the same fuel - or maybe even less fuel, since it's more direct - but that's not what happens.

Fuel use is not linear on distance. one 10LY jump does not use the same fuel as two 5LY jumps.

This is pretty obvious when you look at the fuel gauge and your rebuy costs, but it's not immediately obvious how much fuel you will use for a certain distance. If you want some more details on that, take a look in the next section.

You can decide between the two, but which one should you pick?

Flying as fast as possible within your maximum range

Always use fastest routes. you take fewer jumps, which means less time.

Flying as fast as possible exceeding your maximum range

Always use fastest routes, and scoop as much as you can until you can reach your last jump. You can check this (while you're scooping is the most efficient way!) by looking on your galaxy map - if you have a dotted line on your final jump, you can't make it all the way yet. If you have a solid line, you're good to go.

If you do care about your fuel costs, then always use fastest routes and scoop as much as you can on every jump you can. This way you'll only pay for fuel on your last jump (or you can scoop before heading in to the station if you wish).

Since the March 11th update, fuel costs are now tiny, even in bigger ships. Buy as much fuel as you can when you get to your destination.

Using economical routes is slower than jumping and scooping unless you have a rubbish scoop and you're bad at scooping.

And to prove it, here's some math! Yay!

How long does it take to scoop?

You can see the fuel scoop efficiency here:

I ran my timing tests with a 2B scoop (65 units per second max). There's 1000 units per one ton of fuel (let's assume 1 unit of fuel is 1 KG of Hydrogen) so scooping 60 units per second will take 17 seconds to fill one ton of your fuel tank.

The worst class 2 scoop scoops at 32 units/s. That would take around 35 seconds to fill one ton of your tank at just under max scoop.

You can safely scoop at 90% of your max scoop rate while staying at a decent temperature - I tend to fly into the star until I'm at 70% rate, slow to minimum supercruise speed and blip the throttle until I'm sitting at 90% scoop rate or above, then level out (and orient myself so the target jump star is above me). Once the scoop is finished, or even better nearly finished, I point up to the target star and accelerate at max, then charge the FSD as soon as the temp drops below 56.

How long does it take to jump?

Here's some timings taken in a Cobra with a 4A FSD and D class systems.

A jump will take around 43 seconds on average assuming you do the best job you can of jumping as soon as you arrive. This is made up of:

10 seconds waiting for FSD cooldown upon arrival
13 seconds of charging time
5 seconds countdown to enter hyperspace
12 seconds inside hyperspace
3 seconds to exit hyperspace

entry, exit and transit times can vary by a second or two each way depending on network connection, lag and other factors, but your own response times and piloting skill probably make as much if not more difference. I did manage to do a few jumps in under 42 seconds but it's pretty hard work.

If you round this up a bit, you can safely say that your typical jump will take 45 seconds.

Jump or scoop?

Bear in mind that you can be scooping during the FSD cooldown phase, so you can get 5 seconds scooping for free if you're smart. add another 30-50 seconds to fill your tank. On average, you're better off jumping to max and scooping rather than jumping twice, and you're definitely going to go much faster doing this than jumping three times to get the same distance. This also assumes you want a full tank at your destination.

If you're happy to arrive with a nearly empty tank, then you're always best off scooping and max jumping as long as you are competent at scooping, even if you have the worst class scoop. Better scoops save you more time (or money, your choice).

Example numbers

Here's an example from some runs I've made between Orrere and Witchhaul. This is in my Cobra with 4A FSD, D class just about everything else apart from the scoop (2B) and a full cargo load of 40 tons.

Jumping with an Economical route:

31 jumps (193LY as the crow jumps, but actually travelled 237LY)
Average jump distance of 7.65 LY
Total time for journey: 26.5 minutes
Total time just jumping: 22.5 minutes
Time taken launching and docking : 4 minutes
Fuel used: 59%
Fuel left on arrival : 41%

Jumping with a Fastest route:

11 jumps (193LY as the crow jumps, but actually travelled 208LY)
Average jump distance of 19.0LY
Total time for journey: 15.5 minutes
Total time just jumping: 8 minutes
Total time scooping : 3 minutes
Time taken launching and docking : 4 minutes
Fuel used: 130%
Fuel scooped: 55%
Fuel left on arrival: 25%

How much fuel do I use to jump?

Fuel use isn't linear, as I said earlier - so how can you figure it out? Well, here's the results of some of the tests I've run.

These are all in a Type 6 with a 4A FSD, but I'm pretty confident they'll be applicable to all ships / FSDs - just because the math is so close to correct. I'll be trying out different ships over the next couple of days to confirm this result.

(Update2 - Taleden has linked me to a dev post describing the correct formula for fuel costs, which also describes your maximum distance.)

Distance jumped -> fuel usage (3.0 tons max fuel per jump, 20.61LY max range)

4.05LY -> 0.08 tons
10.24LY -> 0.60 tons
15.15LY -> 1.44 tons
20.36LY -> 2.89 tons

Your fuel usage appears to be (update2! slight change to formula!):

((Jdist / Jmax) ^ Power) * Dcap

Jdist is the jump distance to the target star system.
JMax is your current maximum jump distance.
Power is specific to your ship's FSD class (see below)
Dcap is the drive capacity. See "Max fuel per jump" for each FSD class.

Power varies by FSD class.

FSD Class23456

(I had previously, incorrectly, guessed at Power as a constant for all ships - and given I'd worked out it was 2.3 or as close as possible in my tests, I'd assumed FD would pick some high-falutin constant, and the Universal Parabolic constant was a great match! turns out I was wrong.)

So, as an example, if you jump 16.0LY with a max dist of 21LY, a class 4 FSD and a max fuel per jump of 3.0 tons, your fuel usage will be:

((16.0 / 21.0) ^ 2.3) * 3.0 = 1.60 tons.

As a rough approximation, since you probably don't want to hit up a calculator every time you jump:

half your max jump distance will cost you 0.2 * Dcap fuel.
3/4 of your max jump distance will cost you 0.5 * Dcap fuel.

If you want to see the numbers / research methodology on this, drop me a comment!

No comments:

Post a Comment