Mass Manager vs Deep Charge

With or without deep charge, your FSD will still give you the same jump distance per liter of fuel. The boots just allows you to use more fuel on a jump to give you that much more range on a single jump.
Fuel efficiency goes down with jump range. It's not linear.

Here are two stock Anacondas with roughly the same jump range, one using optimal mass, the other using additional fuel.

Additional fuel only has half the total range, hence half the fuel efficiency.
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Only if the ship is making MAX range jumps. Max range jump would include the extra fuel needed to go the extra distance.
On an economical plot, they should have the same range.
The entire point of this thread is comparing max range between the two methods.

One method uses more fuel for the same range. You can scale it down if you like, but because it has a worse optimal mass - it still uses more fuel at any point.
Ahh yes. Optimal mass. I was thinking the two FSDs had the same optimal mass and just one had the extra fuel boost.
Optimal mass does improve your fuel efficiency which is how you can go further on the same amount of fuel.
The deep charge give you extra range by adding fuel instead of going further on the same fuel.
Right. Because of the optimal mass consideration even if the results were linear a higher optimal mass is "safer" than a higher fuel usage per jump number. However, as the OP already noted, the higher fuel usage can get you a higher actual jump range. So it can be a tradeoff: do you want maximum jump range and to use more fuel along the way or do you want a lesser improvement to jump range and use less fuel along the way. In speed considerations you should also factor in how good your fuel scoop is. A lot of people forget this and think "longer without scooping" (aka large fuel tanks) makes everything faster, but if you have to scoop more fuel at the same rate then it takes the same length of time (eg the extra tank size just results in a bigger buffer with no effect on speed at all except insofar as you may have to go off course to refuel more without that buffer and this of course takes time.) As an example, let's say it normally takes you, oh, one minute to fully fill your tanks. If your jumps use more fuel it still takes that one minute but you have to fill them more often, thus taking that extra percentage longer during a long trip. Adding, say, 25% more fuel lets you go 25% longer without refueling, but then it takes 25% longer to refuel (so that one minute example becomes one minute and fifteen seconds) so the net result is the same except you have a bigger buffer against accidents and having to go off course. Without more fuel, if you have to scoop 25% more often it means the same net result as taking 25% longer to fuel. (This is not factoring in the non-linear nature of the effects of weight on jump range. Which I guess the game's course plotter doesn't do anyway?)

Thus, deep charge versus optimal mass is more complicated than just which one nets the highest percentage of jump range increases. I couldn't say where the balance point is factoring in these other considerations -- that's a math I wouldn't even care to attempt due to the non-linear ratio (maybe the OP is brave enough?) But using more fuel means scooping more often, making this is a tricky decision.
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Lovely work everyone, especially the OP. I love equations too, but I love them even more when someone has done them for me. :)

I just had a play with my new Chieftain. Took me longer to get the Datamined Wake Exceptions for the G5 FSD than all the stuff for the experimentals combined. I tried the Mass Manager, Deep Charge and -- for a laugh because I had buckets of spare materials -- Stripped Down experimentals. The results matched the OP perfectly; +1.13ly maximum with Deep Charge, +1.17ly with Mass Manager, exactly what you would expect with a Class 5 drive. I found this thread when I Googled to make sure my conclusions matched everyone else's.

I have no reason to doubt the validity of the equations, and will be going for Mass Manager on my Anaconda when I get her back to the bubble later this weekend.

FWIW Stripped Down gave me +0.21ly which makes it kind of useless as an FSD mod for exploration purposes. I guess it might find a niche in combat builds where you're trading mass for manoeuvrability and the range boost is a bonus.
Well, mass manager has actually given me 1 whole light year more than deep charge on my python, with the max level 5 fsd with 5 grade mod.

My question is, would extra fuel tanks have an effect on the overall jump range with a deep charge effect?
Nope. Extra fuel tanks only allow you to do more jumps before you have to refuel. On the other hand, since the route plotter uses the full tank jump range, you'll find that the more fuel tanks you carry, the lower your effective jump range will be.
Awesome! Have some Rep, CMDR!

Very glad to see that my basic observations were right on the money regarding FSD Class and choice of effect.
This will probably come up a lot when 3.0 drops, so here's your guide to which one to pick in order to maximise jump range.

To recap:
Mass manager: gives you a 4% increase to your optimised mass. This multiplies with any base optimised mass increase you have from the increased range blueprint.
Deep charge: gives you a 10% increase in max fuel per jump.

Tl;dr - mass manager is best for larger FSD classes; deep charge is best for smaller ones. The break-even point is a class 5 FSD; in that case choose mass manager because it will be more fuel efficient.

The maths

If like me you like equations almost as much as you like playing Elite, read on for the details...

We begin with the hyperspace fuel equation:

  • f is the fuel required (tons)
  • d is the distance to be travelled (light years)
  • M_ship is the mass of your ship (tons)
  • M_opt is the optimised mass of your drive (tons)
  • l and p are constants defined by the rating and class of your drive, respectively

This governs your maximum range, because your drive cannot consume an unlimited amount of fuel per jump. This is why, if you select a system beyond your maximum range and attempt to jump, the error you get is 'max fuel exceeded'.

Rearranging, we get

Now we can see more clearly the factors affecting our maximum range. It scales linearly with optimised mass (irrespective of anything else), but any multiplier of maximum fuel is raised to the power of 1/p. The question, therefore, is which gives the higher multiplier: a straight 1.04 (Mass Manager) or 1.1^(1/p) (Deep Charge)? This calls for a spreadsheet! I like spreadsheets.

FSD classp1.1^(1/p)

You can now see that they give the same result for a class 5 FSD. Mass Manager would actually have a tiny advantage because M_ship includes the mass of the fuel needed for the jump, but it's already the best choice because it is more efficient.

CMDR, ty for the time spent doing the mats.-


+Rep for you!
An example to confirm

I've a lightweight Asp Explorer. No guns, no utility mounts, lightweight alloy bulkhead, small core and optional internals with some (but not all) Engineered Lightweight mods.

I thought it would fall on the 'Deep Charge is better' side of the jump range equation, as its FSD is class 5 and it has low mass, but no. The following stats are for Completely unladen / With fuel / Fully laden.

Mass: 397.2 / 500.6 / 1,260.0

Jump ranges:

Deep Charge
53.63 / 49.97 / 39.65

Mass Manager
53.72 / 49.98 / 39.66

Thank you OP!
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