Juno: New Origins | Electric power cycle engine runs way to short on batteries

(much edited, sorry for the confusion)

In the game a 100MJ (27.75kWh) battery can run a small (30kg, 17kN ASL) electric power cycle engine for about 5 seconds, meaning it uses about 300 times as much electric power as its real life counter part (see below).
The engine says it uses a reasonable 8kW electric power. If that's true it should run for 3.4 hours on a 27.75kWh battery instead of only 5 seconds, that's off by a factor 2500.

example craft

bug report

As a result it is not possible to build an Electron-like rocket in SR2 - not even one with a single 1st stage engine instead of nine.
To run such a 1st stage for 150 seconds the battery would have a mass of about 4500kg, which is like 3 times as much as the entire rocket when equipped with a gas power cycle engine instead.

For reference:
Rocket Lab's Electron rocket has 9 "Rutherford" electric power cycle engines on the first stage, each with two 37kW electric motors, total power requirement 9x2x37=666kW. The motors are powered by batteries.
The 1st stage runs for 150 seconds, meaning the batteries provide 27.75kWhour or about 100MJ of energy. I don't know the mass of the batteries but it's definitely not more than the entire rocket.

235 bspawn

The bug has been acknowledged by a dev; it's probably a factor 1000 conversion error somewhere.

2.0 years ago

285 Toinkove

yeah this is exactly what happened when they tried implementing power usage by electric pump fed engines in the 0.9.000 updates. I even get the exact same results: 26 kN thrust electric engine requires a 1.1 GJ battery to run for 57 seconds!

the only thing different now is that older 'pre-update' engines don't use power so older craft (including those in the tutorials) will function.

Try a standard Ion engine (no editing or resizing) you should find is uses around 247 KW of power (far more then a 20-26 kN electric engine) but it doesn't eat up a battery nearly as fast as the electric pump engines do!

@Vedhaspace The 300 number includes the factor 9 of the number of engines. But further investigation shows there may be something wrong with the batteries, not with the electric power cycle engines (see my edit of the opening post).

13.7k Vedhaspace

@bspawn whoa that's like 300X9 lol

@Vedhaspace not to mention that's just one engine instead of 9.

Where is 150 sec and where is 5 sec
That's a very big difference!
Pls fix it

Electric power cycle engine runs way to short on batteries

Tags

6 Comments

1 Upvote