Difference between revisions of "IX-6315 "Dawn" Electric Propulsion System"

Revision as of 16:46, 29 April 2015

IX-6315 "Dawn" Electric Propulsion System
Ion engine by Ionic Symphonic Protonic Electronics
Radial size		Tiny
Cost	(total)	8 000.00
Mass	(total)	0.250 t
Drag		0.2
Max. Temp.		2000 K
Impact Tolerance		7 m/s
Research		Ion Propulsion
Unlock cost		16 800
Since version		0.18
Part configuration		ionEngine.cfg
Maximum thrust	(1 atm)	0.05 kN
	(vacuum)	2.00 kN
Isp	(1 atm)	100 s
	(vacuum)	4200 s
Fuel consumption		0.486 /s
Electricity required		8.74 ⚡/s
Testing Environments
On the surface		No
In the ocean		No
On the launchpad		No
In the atmosphere		No
Sub-orbital		Yes
In an orbit		Yes
On an escape		Yes
Docked		No
Test by staging		Yes
Manually testable		Yes
Packed volume		160 l

The PB-ION Electric Propulsion System is a tiny-sized engine which runs on electricity and xenon gas propellant. It's modeled after the real-world Hall effect thruster.

Usage

This engine has a phenomenal fuel efficiency (4200 s I_sp), but very low thrust and requires an immense amount of electricity to operate. Xenon gas is provided by xenon containers like the PB-X150 Xenon Container. Electricity can be obtained using solar panels and radioisotope batteries. The amount of electricity needed to keep one ion engine running at full thrust is roughly equivalent to half the output of one Gigantor XL Solar Array (however one array will not power 2 engines), 12 PB-NUK Radioisotope Thermoelectric Generators, or 12 OX-STAT Photovoltaic Panels.

Batteries can be used to store the electricity since there may be times the solar panels will be blocked from the Sun by objects or the dark side of celestial bodies.

The ion engine is good for fine tuning of orbits. It is also a popular propulsion method for planes on planets on which jet engines don't work. Due to its great fuel efficiency it is also well-suited for interplanetary travel, but maneuvers take a long time to complete due to its low thrust-to-weight ratio - it is advised to use it for very small craft, and to use physics-warp while propelling with it.

It is practically impossible to build an ion-rocket which can defeat gravity on Kerbin, because the engine isn't even strong enough to lift itself against gravity, let alone itself and its fuel, a battery and a probe core. But when on a low-gravity moon like Minmus or Gilly it is possible to land, start, enter orbit and reach escape velocity with ion-propulsion alone. As of 0.23.5, it is technically possible to create an ion-powered probe, albeit with a minimum of parts, which will be able to defy Mun gravity. With that in mind, it is also possible to resist gravity with lightweight Ion craft on Duna, Moho, Dres, Eeloo, and every in-game moon with two exceptions: Laythe and Tylo have too high gravity for a single ion thruster, xenon tank, probe core, and battery.

However it is possible, and has even been demonstrated, to build an airplane powered solely on this engine. At that point it should be theoretically possible to build a SSTO still powered by only this engine. This makes it possible to get a craft into orbit from any landable body in the game using just the PB-ION. Ion-powered "ferries" may also be useful for moving fuel, oxidizer and/or kerbonauts between two larger vessels, by keeping the large craft at such range that only one of them is within draw distance from the "ferry" at any moment, performance loss can be avoided. It is generally more fuel-efficient to move fuel and oxidizer between two ships using a ferry than it would be to dock the larger crafts together using their own engines and RCS.

Because it uses only about 0.485 units of xenon per second, one PB-X50R Xenon Container with 400 units of xenon can supply the engine for almost 14 minutes. The other larger tank PB-X150 Xenon Container with 700 units of xenon has enough to supply the engine more than 24 minutes.

Electrical consumption

The part.cfg lists the electrical consumption as 1.8 ⚡ which is the electricity consumed for 0.1 units of xenon (). This is a ratio, and to propel 1  an electricity of 18 ⚡ is required. As seen ingame, the fuel flow is 0.0485 kg/s or 0.4849 /s. The electricity consumption is 8.7285 ⚡/s.^[1] As the I_sp given in seconds needs to be multiplied with a slightly higher acceleration (9.82 m/s²) than g₀ (= 9.81 m/s²) the actual I_sp in m/s is higher and therefore the xenon and electrical consumption is lower. To get the actual consumption the mass flow can be calculated using the specific impulse and thrust: ${\displaystyle I_{sp}={\frac {F}{{\dot {m}}\cdot g_{0}}}\Rightarrow {\frac {F}{I_{sp}\cdot g_{0}}}={\dot {m}}\Rightarrow {\frac {2000N}{4200s\cdot 9.82{\frac {m}{s}}}}=0.04849{\frac {kg}{s}}}$^[2]

Product description

Trivia

Although the 2 kN PB-ION drive is considered to have very low thrust in KSP, real-life Hall effect thrusters typically have orders of magnitude less thrust usually below 1 N (0.001 kN). They make up for this by having a service life of thousands of hours of continuous operation and consuming fuel extremely slowly, which would have been impractical in the game.

Gallery

• 

  A Solar Glider Ready for take-off. This ship uses ion engines.

• 

  The Solar glider in action.

• 

  The Ion-Powered Space Probe stock craft, powered by an ion engine.

Changes

0.25

• Moved to Propulsion from Utility.

0.23.5

• Ionic Protonic Electronics renamed Ionic Symphonic Protonic Electronics, description changed, thrust increased from 0.5 to 2, relative electricity reduced from 12 to 1.8.

0.18

• Initial Release

References

1. ↑ Answer in the forum to Ion Engine consumes more energy than it should.
2. ↑ In File:10X Xenon.png 10 PB-Ion engines are running at full power and consuming a lower value than 10× the theoretical value.