Kerbal Engines to Real Life Engines

[TheGamingNoobster]

This is just a small thing I noticed. The Shuttle SRB's (The SLS SRB's) are over 20x more powerful than their Kerbal counterpart. That is a very unkerbal thing for kerbal to do! Yeah, it already provides enough thrust as is but... Thrust. The engines exerts about 13,800kN of thrust.

Am I the only one wondering about 1: Why the SRB is so powerful and 2: why Kerbals have such a puny version (A 1/10 thrust ratio would be better not 1/21)

Any biters?

[Ralathon]

The reason is physics and aesthetics. Kerbin is 1/10th the size of earth (roughly).

Because of that you only need 1/sqrt(10) of the dV to get into orbit. If you would use normal Isp and twr ratios you'd end up with very overpowered rockets. Pretty much everything would be SSTO. So they're compensating for that by nerfed Isp's and ridiculously heavy parts.

Also, note that the SLS boosters in real life are much larger than the ones in game. In game they have a diameter of 1.25m and IRL they're a whopping 3.7 meters

[Dkmdlb]

Kerbal engines in general are much weaker than real ones. The main reason is the reduced delta-v to orbit. But that doesn't mean Kerbal engineers are bad, it just means they don't waste resources on things that don't solve problems.

But look at what they have made - engines that can be infinitely restarted, throttle all the way down with no loss of efficiency, never have a turbopump failure, can support the weight of an entire rocket, and have a sea level thrust that is identical to their vacuum thrust.

I'd like to see real life rocket engineers try to match those feats

[magnemoe]

Kerbal engines in general are much weaker than real ones. The main reason is the reduced delta-v to orbit. But that doesn't mean Kerbal engineers are bad, it just means they don't waste resources on things that don't solve problems.

But look at what they have made - engines that can be infinitely restarted, throttle all the way down with no loss of efficiency, never have a turbopump failure, can support the weight of an entire rocket, and have a sea level thrust that is identical to their vacuum thrust.

I'd like to see real life rocket engineers try to match those feats

Let us talk about jet engines a bit

But yes KSP engines would be much better than real world ones for lots of tasks.

[Neil1993]

Let us talk about jet engines a bit

Still much better than the real life counterparts. When last I started a 737 engine, it took nearly 20 steps! APU on, bleeds in the correct configuration, fuel cutoff, hydraulics, fuel pumps, etc. There's just so many things to go through. A KSP engine just needs an intake, some fuel, and someone to throttle up and hit the ignition. Also, KSP jet engines don't require constant maintenance, but I doubt most KSP engines ever survive long enough for that to matter.

[Dkmdlb]

I think he meant that KSP jet engines are more powerful than jet engines in real life.

[Neil1993]

I think he meant that KSP jet engines are more powerful than jet engines in real life.

Not necessarily. The GE90 can produce up to 513 KN of thrust while a Basic KSP engine can only produce 150 KN

[Dkmdlb]

But the GE90 weighs 8t+, while the KSp version weighs only 1t.

EDIT: Some quick Googling shows that the SR-71's J58 engine produced 150 kN of thrust, but it weighed 2.7t.

Edited March 31, 2015 by Dkmdlb
wrong number.

[magnemoe]

But the GE90 weighs 8t+, while the KSp version weighs only 1t.

EDIT: Some quick Googling shows that the SR-71's J58 engine produced 150 kN of thrust, but it weighed 2.7t.

More important, KSP jet engines can go from 0 to over 2km/s, enough to do an X15 style suborbital flight on earth, bonus they hardly use fuel.

See dissuasion about supersonic passenger jets, with KSP engines the question would be supersonic or hypersonic atmosphere skipping.

[Neil1993]

But the GE90 weighs 8t+, while the KSp version weighs only 1t.

EDIT: Some quick Googling shows that the SR-71's J58 engine produced 150 kN of thrust, but it weighed 2.7t.

If we could make planes with a low cross-section like the SR-71 in KSP, we might not need so much thrust

[Bill Phil]

The reason is physics and aesthetics. Kerbin is 1/10th the size of earth (roughly).

Size? 1/1000

Radius? Oh yeah, that's 1/10.

[TheGamingNoobster]

Don't forget that the jet engines in KSP have such a high ISP due to the fact that IntakeAir has no mass. In an actual jet engine, air has mass. The high ISP is very high but the only thing being pushed out of them in KSP is some 'liquid fuel' that is leaving at about 12km/s