high ISP rockets are unusable without acceleration warp.

[Specialist290]

In the same vein as Vanamonde, I can get quite a bit of reading done to pass the time during an interplanetary burn. That time is only wasted if you let it be so.

[Wyrm]

Not with stock parts, at any rate.

This holds true In Real Life as well, there seems to be an inverse relationship between Isp and Thrust.

True dat. Alas.

There are a couple of theoretical propulsion systems that have both high Isp and high thrust, but they are kind of extreme and none of them have even come close to being prototyped. They include the Orion project nuclear bomb drive, beam-core antimatter, and Zubrin's infamous nuclear salt water rocket.

All of which cause varying but usually extreme amounts of !!FUN!! when they are jostled.

PS, love to death your Atomic Rockets page!

[John FX]

True dat. Alas.

All of which cause varying but usually extreme amounts of !!FUN!! when they are jostled.

PS, love to death your Atomic Rockets page!

Any reference to DF always leaves me wondering why people play it. It seems insane. Fun is everybody dying in various ways with no end in sight,over and over, Ooh look I found Iron. And also some form of dangerous creature that kills half my dwarves.

too much like real life for me.

I`ll stick with KSP.

[Merinsan]

The longest burn I ever had was 1hr.

I've since learnt to add more nukes. Yes, you lose delta-v, but think about it - The nuke is only 2.25t compared to the fuel you might be carrying, which for me is from 80t-150t (depending on the ship). Adding 1 nuke is not going to hurt delta-v much. In my case adding 3 made sense, getting the burn time down to like 20 minutes.

The other thing to be careful of is to make sure your ships are designed so they can handle physics acceleration. A number of my ships that go to Jool can go at 4 times acceleration while burning, the rest 3 times. I recently built a new space station hub, which only handles 2x and wobbles too much at 3x. I just recently upgraded it to have 2 nukes so I could put it around Duna. When I put one around Laythe, it will need more fuel and more nukes, or more stability for the physics warp.

[Itsdavyjones]

The longest burn I had was three hours, with the dozen orbital boosts and maximizing the gravitational assists from the Mun (two of them) and then burning out beyond Eeloo's orbit to do a solar power test on the remote tech satellite. Ofcourse the design I had also used the last of the assent stage to boost as much as possible, but with a max acceleration that I observed of 30cm/s^2 it was painful... Last time I use ions. But if you want high power and ISP go get the Orion drive mod. Currently still in development, but works wonders.

[Krizzen]

You could use the mod KSPX's larger nuclear engine. It's quite balanced against stock parts, and can help reduce part count while increasing TWR, of course while keeping a nice ISP. The only trouble is it *might* get added to the official game since the KSPX developer was hired by Squad. This creates trouble because you have a toss up between using the old, unsupported part over the new, stock one.

Anyway, just an idea.

[ComradeGoat]

If we were doing this in real life, it would be an absurdity to use more than one engine for interplanerptary departure/transfer (other than for redundancy): a burn of hours for a transfer taking months is peanuts. However, this isn't real life and we have other things to do, so we have a choice: try and play this as if it's as close to reality a simulation as possible, and realise that spaceflight happens S…L…O…W…L…Y, or realise we aren't spending real money, add some fuel and use more engines.

[John FX]

You could use the mod KSPX's larger nuclear engine. It's quite balanced against stock parts, and can help reduce part count while increasing TWR, of course while keeping a nice ISP. The only trouble is it *might* get added to the official game since the KSPX developer was hired by Squad. This creates trouble because you have a toss up between using the old, unsupported part over the new, stock one.

Anyway, just an idea.

I like the 1.25M 300Kn NERVA from the NovaPunch addons. I only use this and the heavier strut from the whole pack though (so I only install those) and the pack itself is a bit large.

[Xarian]

There should really be an acceleration warp function, which would work at very high altitudes, such as orbiting the Sun. The way it works is you just enter the amount of deltaV you want to expend, and it instantly add in the correct amount of time and velocity while subtracting fuel.

An acceleration warp feature is certainly a good idea, but this implementation wouldn't be particularly realistic (or enjoyable, since it's fun to watch your craft do crazy things at high timewarp). Since getting that deltaV may take hours, your position would also change significantly by the time you reached that acceleration.

Enabling acceleration during timewarp for low accelerations would be the best choice, but it would have to be carefully done so as not to cause PhysX to break. It might be possible to create a mod with those types of engines - they would produce no thrust, but the mod would automatically update your craft's velocity and fuel over time (which would also take timewarp time interval into account). This would create the effect of acceleration without using the physics engine, so it would be usable during timewarp. There are tricky parts - you would have to use a toggle workaround for the throttle, since you can't timewarp with the throttle up. Fuel consumption would be easy to deal with, but regenerating fuels (e.g. electric charge) would be much harder to take into account - not impossible, though! Limiting the feature to low accelerations would be best, so shutting off the physics engine wouldn't be that unrealistic. Such a mod may just require adding a PartModule to the Nuclear engine and the Ion engine and wouldn't be all that hard to code. I'll try to look into it soon, if I can remember.

[Horn Brain]

Sometimes you need MOAR thrust. Even in space.

Just because you're in space doesn't mean that suddenly you don't care about thrust at all. Having a higher thrust allows you to better approximate impulse burns which are usually more efficient than finite-lenght burns. For example, on an outbound interplanetary transfer, if you have a thirty minute burn, that's about a full Kerbin orbit! Obviously you're going to waste a ton of fuel burning at weird angles that you wouldn't have to waste if you brought more thrust. Therefore, there is still a balance between Isp and acceleration, even in space!

The way to use low thrust in space would be to do small burns at the point in your orbit where you want your periapsis to be each time you go around. This will take hours or days real time, and even if you had 10x physical warp, it wouldn't help much because you'd spend most of your time making sure everything was lined up and starting and stopping the non-physical warp at the right times. Additionally, you can't be sure that you won't hit the Mun's SoI by chance and screw up your orbit!

This is why even NASA designs large transfer stages to Mars with multiple engines despite the mass penalty. You save fuel on big burns, you don't have to slowly spiral away from Earth and spend weeks in the Van Allen belts, and there is much less chance of something going wrong (imagine losing an engine halfway through this process. Bummer.).

So in short, what I'm saying is: That's space, bro.

[RuBisCO]

With Mechjeb, Alarmclock, RealFuels and Damn Robots I get around the kolar system with ships having 20,000 dV at there disposal. I have a Ship with 8 huge ion engines and 16 huge solar panels, 8 per robotic arm, Lock rotation to face the sun during a mechjeb burn and timewarp, put in a pause alarm and then go get food, watch tv, etc, etc. Its sad the ion engines are of little us without mechjeb, real life ion engines though would burn for months and we would need a semi-physics time warp to do that plausibly in this game.

[draeath]

Grab one, and grab a book

[Infinitas]

Not with stock parts, at any rate.

This holds true In Real Life as well, there seems to be an inverse relationship between Isp and Thrust.

There are a couple of theoretical propulsion systems that have both high Isp and high thrust, but they are kind of extreme and none of them have even come close to being prototyped. They include the Orion project nuclear bomb drive, beam-core antimatter, and Zubrin's infamous nuclear salt water rocket.

SABRE may do it in RL. But since nobody knows yet what the ISP etc will be, any KSP version is guessing.

[Scottiths]

Create maneuver node. Have mech jeb execute it. Come back 30 minutes later

[tntristan12]

You're gonnna need to execute that in multiple burns, because 30 mins is an entire orbit around Kerbin.

I keep a set of auxiliary engines that are higher thrust but less efficient, specifically for burns I need to execute in a relatively short span.

[llamatoes]

Trust me, long burns are nightmarish, especially with craft that will explode when phywarp even looks in their general direction.

I think this bugger accelerated at about a tenth of a gee.

I think i got through six Game of Thrones chapters in the departure burn to Eeloo alone.

[DChurchill]

You could use the mod KSPX's larger nuclear engine. It's quite balanced against stock parts, and can help reduce part count while increasing TWR, of course while keeping a nice ISP. The only trouble is it *might* get added to the official game since the KSPX developer was hired by Squad. This creates trouble because you have a toss up between using the old, unsupported part over the new, stock one..

I wish I'd have had KSPX when I built this:

Edited July 18, 2013 by DChurchill
Grammar.

[CrazyCoco]

Use ALT+. for a different kind of time accelerate (don't remember its name) that allows you to accelerate time while your thrusters are on.

[Spatzimaus]

High-ISP engines work just fine; you just have to think SMALL. It's too easy to make bigger and bigger rockets, and when you do that the time needed (sans mods) becomes prohibitive. But if you've kept your transfer stages relatively small, then those engines work just fine.

It's the same as with spaceplanes; there, it's all a function of how small you can make your design, and it's a constant battle to keep your designs from getting too bloated to leave the atmosphere.

[Khrissetti]

I tend to make my interplanetary stages huge monsters which take hours (Sometimes literally) to boost anywhere. My technique is to just slap the ASA on, keep the window in one half of the screen while I get on with writing or something in the oher half.

[Mephane]

infamous nuclear salt water rocket

Woah, I did not know about this concept. This is totally something Kerbals would do. XD

[Wheffle]

I'm kinda hoping they get physics warp to be more stable at least, but I'm not holding my breath. That's a tall order, especially in early development.

[John FX]

Use high thrust low ISP or jets for first stage, use mid engine for orbit insertion, NERVA for orbit burns and to get away from kerbin. Then your orbit is measured in years and you are in the playground of the Ion engine.

You wouldn`t use a NERVA in the atmosphere, why use an Ion engine in planetary orbit?

They simply are not suited to that environment.

Even with a NERVA though, it`s easy to get 12k+ Dv in a small package and there is not much use for more Dv unless you are returning from a Moho or Tylo landing.

[0x7be]

30 minues?

Fine, I just kick-off MechJeb and go play with my kids or punch few lines of code

[ASnogarD]

It would be more 'fair' to stablise the physics warp when they have implemented some manner of time resource, sending out your Kerbils for 3000 years so you can use 1 low thrust high ISP engine but by passing the time YOU spend, should cause loss of control of the ship when the skeletons of your Kerbils fail to resurrect and assume in death their life tasks .

That and perhaps some supplies to keep your Kerbils alive, just to make it less point craft at target and warp time until you arrive.

It just seems odd you can go oops missed my burn ah well time warp a few years while the poor Kerbils sit in a small capsule waiting patiently.