Temstar

Hmmm interesting. That means the ideal nose cone would be a rather blunt shape to deal with hypersonic flight, where it lifts the shockwave away from the nose and therefore reduce heating. This would for example allow you to attend higher speed on jet engine while climbing at very shallow angle without the nose melting. But then also have the capability to deploy a long skinny spike out of the nose to fool the air into thinking it's a pointy cone when the craft is flying at supersonic speed, ie while flying in lower atmosphere where heating is not a big issue and low drag is more important.

This is not a huge problem, because the only type of Orion that need that kind of Isp are interstellar ships, and those have plenty of time for thrusting anyway. Dyson's "energy limited" Orion takes this into consideration and it has 0.00003g of acceleration. This ship by the way is 20km in diameter and has a 5 million ton copper pusher plate. The alternative is to use open cycle cooling where you accept that each bomb will cause some material to ablate away and you design the ship so the pusher plate or whatever ablation system it use can just survive all the bombs. The ship will be useless when it reaches its destination (as in, it can't be refueled with more bombs) but can achieve 1g acceleration for 10 days and so reach 3.3% c.

The propellant and the bomb are integrated into a single physical package and are ejected out of the ship together.

It's a problem with the service bay, its detection for what is stowed and what's not is a bit wonky and too aggressive. If you open up the service bay then you'll be able to deploy all parachutes.

Each orion bomb has a slab of tungsten above the channel filler that gets turned into a cone of plasma, it's this plasma that hits the pusher plate. The other bomb debris and gamma ray play no part in the propulsion.

Currently career mode has two ways of making money - Strategy and contract grinding. Strategy converts Science or Rep into fund, but the return is rather low so it's fairly pointless. People have a beef with contract grinding as the contracts are rather arbitrary method of getting your space program to do stuff for fund. Logically there's little reason why a company would pay you to put up a space station for YOURSELF then pay you for it. One method to inject some life into career mode is to introduce a macguffinite economy. A "macguffinite" in this case refers to some valuable substance that can only be obtained in space away from Kerbin which provides a motivation and income source for the space program. In many ways ore is already a macguffinite. It's an incredibly useful resource that can be converted into LFO and monoprop, which can then be further converted to electricity and delta-V. Unfortunately the only people who really need electricity and delta-V is you yourself, and understandably returning full ore tanks back to Kerbin for recovery produces very little profit. Instead of ore, we could have another resource that may or may not have direct application in the space program but is in high demand on Kerbin and can only be obtained in large quantities in space. It can be anything: blutonium, helium-3, magnetic monopole, room temperature superconductor, anti-hydrogen, tiberium from Magic Boulder, even a cure for male pattern boldness. Whatever it is its price on recovery makes it worthwhile to harvest it and return it to Kerbin. Assuming the macguffinite resides in regolith just like Ore does, the current ISRU equipment could then be made to do dual purpose and be used for macguffinite mining. Survey scanner for example would have a toggle to switch between Ore and Macguffinite overylay, and ISRU converter would also be able to convert raw macguffinite ore into refined macguffinite. All that's needed is a new set of tanks to store the macguffinite. Although I would suggest we could also make use of a set of low tech extraction and refining equipment that is rather inefficient and must be manned by engineers and scientists to do work. I believe the current stock resource system is already setup with this in mind and it's trivial to add another resource. We don't have to be restricted to one macguffinite either, it could be something interesting like there are two macguffinite, one tends to accumulate on worlds closer to Kerbol (eg, helium-3), while the other tend to accumulate on worlds away from Kerbol (eg, monopoles) with Kerbin SOI having a bit of both but not particularly rich in either. A player driven economy like this would make career players really "own" their space programs instead of feeling like a grind.

Also worth pointing out - the hotter your rocket gets without blowing up, the more heat it's capable of radiating away into its surrounding environment. So extra 200 heat capacity could have given you a sweet spot where your rocket is radiating away as much heat per second as its picking up, where as with less heat resistive parts that same sweet spot might have been just out of reach.

Unlike humans who like to count from year 1, POSIX count time from zero, and with the sign bit it creates a situation where the "first moment of the Age of Unix" is also the "last moment before the Age of Unix". Both times are identical and can be represented either as "midnight, 31 Dec 1969" (ie midnight at end of the day) or "midnight, 1 Jan 1970" (midnight at the start of the day) depending on specific software implementation. In fact "midnight" is very ambiguous even for us humans. If you tell someone to meet you in a dark alley at "midnight, 16th Feb, 2016" there are two different ways to interpret that. However if you told him instead "meet me at a dark alley, 1455580800 seconds after Unix epoch" there is no confusion.

It's the start of the unix epoch, the server running the forum must be running a posix OS (probably Linux) and for some reason the timestamp for the two posts have zero values, which translate to zero seconds after the unix epoch. I work on Solaris and Linux as part of my day job.

There's no such concept as "up" in the editor, your navball orientation depends on orientation of the root part or the first "control from here" part.

Aww man why did you have to open up that can of worm? I thought you were tired of that debate.

I still don't see why there's a need to identify first child. Wouldn't you just have every part that's attached to the new root (via either radial or node) be the first generation children of the root? What's so special about this first child?

Why are you being so difficult? Yes most rockets these days don't use fins, just like how most well designed rockets in KSP don't need fins either. But at times, you run into problem in KSP where for whatever reason, your rocket does need more drag stabilization. In those situations fins are the answer - they create very little drag when edge on to the airflow, but when the rocket move away from the prograde the fins produce a torque that try to pull the rocket back into prograde. Airbrakes are bad because once they are deployed, they create a huge amount of drag regardless of how far your rocket is deviating from prograde. Yes they will make the rocket very stable, but that comes at a huge cost to aerodynamic drag. If you have to restart to airbrakes it's an indication there there's problem else where in either the rocket design of the ascent profile and you should work on fixing those first.

When was the last time you saw a rocket deploy airbrakes at launch for stability? And for the record, Falcon 9's first stage deploys grid fins for aerodynamic control.

Metallic hydrogen is useless to us. It's only meta-stable metallic hydrogen that would be useful to us and they may or may not exist.

Let's not generalise too much. Whilst that's true for KSP's LV-N when it switched from LFO to LF, it's not true in general. In general, NTR's performance does depend on fuel mix - the lighter the average molar mass of the exhaust, the higher the Isp. And this does come up in KSP as well once you start to deal with mods that introduce cryogenic fuels.

Why do you want to spaceplane to the Mun?

You've just came upon the concept of air turborocket. It's certainly doable, but it's a bit hard for Squad to implement as we've never built one in real life that's designed for the purpose of using inert atmosphere as working fluid, thus there's no easy performance figures to copy unlike say SABRE engine. I would argue that if a species is advanced enough to be able to create air turborocket for the purpose of exploring planets with inert atmosphere they would also be advanced enough to create nuclear turbojet. And so if they want to create a craft to fly for extended time in an inert atmosphere they will go straight to the nuclear option.

Just decouple your nose cone once you've turned off your engine and is on your way coasting to AP. Unless you're THAT good at getting a nearly circular orbit with one continuous engine burn your PE will usually be quite low (read - below the ground) while you're coasting. And if you're really that good at getting a circular orbit with one burn then you'll just have to cut the engines while PE is still below ground, jettison the nose cone off to the side then start the engine back up.

Yeah it's close to 50/50 but not exactly, usually the part before the node should be a little bit longer than after the node. I tried to compile a list of experimental data to come up with some rules of thumbs on how to split the burn using follow the prograde but it turns out no such rule is possible - the split not only depends on TWR when you start the burn, but also on TWR at the end of the burn. Since TWR before and after depends on the size of the burn and the total delta-V of the ship / its dry mass not only will be split be different between different ships of differing TWR, it will also be different for the same ship for different sized ejection burns.

Even if you do use tiny probes, it's easier to just have a claw on the depot to handle dodgy crafts. The claw has the added bonus that you can even dock things without docking port.

You don't have to follow the node marker, the burn can also be completed by following the prograde marker so you never deorbit yourself. When you follow the node marker for the entire burn you get zero cosine loss but some gravity drag, due to having some component of the burn in or against the direction of gravity. When you follow the artificial horizon on the navball for the entire burn, you get zero gravity drag, but some cosine losses because some of your burn has radial component relative to the node. You start the burn before the node so the radial is in one direction which is cancelled out by the radial component in the opposite direction from the part of the burn that's perform after you've passed the node When you follow the prograde market on the navball for the entire burn, you get some gravity drag since prograde starts to move away from the artificial horizon once you start your burn, you also get some cosine loss because prograde does not follow the node exactly. The sum of gravity drag and cosine loss should be lower than either the "follow the node" method or the "follow the horizon" method.

For Moho take the calculator result with a big grain of salt. There are three things going against you when going to Moho: Moho is on a rather elliptical orbit for a planet, transfer calculators generally assuming a circular orbit which fits well for most planets in the Kerbol system but not Moho, Eeloo or Dres Moho is on an inclined orbit, transfer calculators generally assume target planet is orbiting on the ecliptical plane, which fits well for most planets but not Moho, Eeloo or Dres Moho is deep within the gravity well of Kerbol, which makes reaching it very expensive in terms of delta-V to start with and makes orbital maneuvers like inclination change or changing orbital phase very expensive, making Moho a much harder target than Eeloo or Dres. Because of the above 3 reasons, a trip to Moho need a huge amount of delta-V, which generally mean your craft will have a very low TWR to squeeze as much delta-V out of a craft as possible. Since an ejection burn to Moho is on the order of 2000m/s it will take many minutes for a low TWR craft to complete the burn. Therefore it's not possible to both place and perform the ejection burn and hit the correct ejection angle with high accuracy from first principle. You will have to use quick load to recursively work out how long you need to start the burn early to hit the correct ejection angle by the end of the burn. As for the node, you will have to manually adjust to compensate for point 1 and 2 above, so don't worry about placing the node with 2 decimal places of accuracy - just eye ball it is good enough.

This, this is the key. When you add airbrakes they take off some of the heat load off the part that's directly facing the re-entry plasma sheath, thus decreasing the peak heat load off that part. Here's an example of mine, the part that's directly facing the re-entry plasma is a Mammoth engine:

42 ton payload with a 300 ton SSTO spaceplane (14% payload fraction) is pretty bad - you can hit that payload fraction with a single stage, no lifting surface rocket. In fact yours truly shows it's possible to build a SSTO, 100% recovery rocket with more than 15% payload fraction. I'm no expert at SSTO and my work horse cargo SSTO that I use in my career manages 34 ton of payload for a maximum take off weight of over 130 tons for 26% payload fraction, and that's a career craft with all the trimmings like RCS, docking port and so on. The extremely efficient crafts in payload fraction challenge is getting more than 50% payload fraction.