Temstar

Parking orbit opens up the launch window. In a one shot method you have a launch window of maybe about 1 hour each kerbin day. Using a parking orbit you get one sigment of your orbit as launch window every orbit. In real life using a parking orbit have weight penalty since the departure stage needs to have on orbit re-ignition capability and electrical/hydraulic power to stay "alive" while waiting in orbit. Even then the effect on launch window is so useful that Saturn V was designed for it.

Kethane and propellant depot like this go hand in hand. Without locally produced propellant all depots must be refilled with Kerbin launched tanker rockets. It's hard enough to keep a munar depot fuelled given that tankers must do at the minimum a TMI to bring that fuel to the depot, which means something like for every litre of fuel delivered to munar orbit six litres were burnt just to lift that one litre out there. If you want to keep a depot even further from home, say in orbit around another planet then astronomical amount of fuel and rocket hardware will have to be expanded to deliever a tiny amount of fuel. However, if you didn't have to lift fuel from deep gravity well of Kerbin surface then the equation changes. At 1/6G fuel produced on Mun could be very cheaply lifted into orbit, even Kerbin orbit by reusable nuclear tankers launched from the Mun's surface. Seen as Kethane engines don't exist yet I think the best place to put the Kethane refinary would be right at the mining site on the surface. So you have a fleet of rovers on the surface. Some drilling for kethane. The extracted kethane gets pumped to a mobile refinary to be turned into bipropellant or monopropellant and then the product is stored in tanker trucks until enough is accumulated for a tanker rocket load. Then you land the nuclear Mun tanker nearby. Have the tanker rovers drive up and fill up the rocket and off it goes to a depot. Alternatively you could build a orbital kethane refinary with pump, converter, ORDA fuel transfer systems and all three tank types. Equipe the kethane refinary with this ORDA/Erkle docking system on the nose and dock with the propellant depot and use it as an add on module to the depot. I don't want to add kethane refinary capabilities to the depot itself as that's another mod you have to install to get it to work and it kind of dilutes the purpose of the depot. I'll rather we keep different capabilities in different ships and dock them together as required.

So why do we calculate Isp and TWR for engine then? Isn't the whole point of calculating these values for different engines is so we can compare them? Now let's have a look at your lander. 6400L of fuel is a lot of fuel for a lander and I can only assume it's intended for both TMI and TKI as well as the actual landing. That's exactly the point I said earlier - if you're going to burn a lot of fuel with these engines then the 20s higher Isp will catch up. But if you're using Poodle then it means you're firing them out of atmosphere. If you're going to fire an engine in space and burn through that much fuel with it then why not use atomic rocket? Take your poodle lander for example, the service module is 48.17kg fuelled and 32kg of that is main engine fuel. I ran it through my own Tsiolkovsky rocket equation and 4177m/s is about right, not withstanding dumping fuel tanks and RCS fuel usage: ln(48.17 / 16.17) * 390 * 9.81 = 4176.27m/s TWR on Kerbin is (220 / 9.81) / 48.17 = 0.47 But why would you build a ship like that? Instead of a Poodle, let's swap it out for four LV-N atomic rocket motor, the ship is now 54.67kg fuelled and still have 32kg of fuel. If we plug that into Tsiolkovsky rocket equation: ln(54.67 / 22.67) * 800 * 9.81 = 6908.38m/s TWR on Kerbin is (240 / 9.81) / 54.67 = 0.45 But Tem they say, I can't live without at least 0.47 Kerbin TWR. Well okay, let's be inefficient and put 5 LV-N on: ln(56.92 / 24.92) * 800 * 9.81 = 6482.26m/s TWR on Kerbin is (300 / 9.81) / 56.92 = 0.54 So there you go, instead of a Poodle, if we instead put on 5 LV-N engines on you end up with the same ship but with 55% better delta-V performance AND 15% better thrust to weight ratio despite LV-N's terrible TWR. So why would you use Poodle?

I think vernier thrusters with big deflection range are really cool looking (Atlas with its pair of vernier thrusters at launch looks awesome) but they're not very efficient use of weight. These days I think only R-7 rocket family still uses vernier thrusters. Why would you need a rocket that could turn on a dime anyway? You only need a little bit of control to keep it straight at lift off and then a little bit more for gravity turn.

You mean like the V-2? But the gyroscopes still control stuff to keep the rocket on track. In the case of V-2 it's rudders and graphite exhaust vanes. You can build spin stabilized rockets I suppose, but that's still diverting some of the thrust into spinning the rocket so as to keep it under control rather than an uncontrolled rocket going straight by itself.

A rocket is like a barely controlled sustained explosion. It's an inherently unstable machine that require active steering to stay on track, as Robert Goddard found out after launching his. It's impossible both on real life and in KSP to build a rocket that goes straight without active steering. Since manual steering is quite hard you'll generally need ASAS or other autopilot on your rocket. SAS is a reaction wheel, it can exert force to make your spacecraft rotate on any of the three rotational axis. The command pods have a built in miniture SAS which is sufficient for small ships. ASAS is completely different, ASAS is a computer that uses any tools that can provide steering force (SAS, command pod SAS, control surfaces, gimbling engine, RCS system) to keep the rocket on the same heading when toggled on.

No I meant it's moot because if the argument is "I'm going to burn a huge amount of fuel in orbit where the 20s Isp actually adds up to make a difference" then I would point out that there's an engine with 410s better Isp that you should be using instead for that ship. So: If you're moving around a 15 ton spaceship that's mostly fuel, you should be using LV-T30 to save engine weight If you're moving around a 85 ton spaceship that's mostly fuel, you should be using LV-N to really take advantage of that 800s Isp, in clusters if you need thrust If you're moving around a 85 ton spaceship that's 15 ton of fuel and 70 ton of dead weight, you should be using LV-T45 to save engine weight yet still have gimbling.

You might want to try the version without mobility enhancers, it's towards the bottom of page 1. It's got something like 150 less parts.

But that comparison is moot, you would never build a spacecraft with 85 tons of fuel and one Poodle. If you really plan to burn 85 tons of fuel in a spacecraft you would build a spacecraft with 78.5 tons of fuel and four nuclear rockets.

Unlike their 0.16 incarnations, 0.17 renamed and buffed the performance of the two big engines. But still, they seem rather worthless to me: Mainsail 280s atm Isp 330s vac Isp TWR 25.49 Poodle 270s atm Isp 390s vac Isp TWR 8.97 Compared to the small engines: LV-T30 320s atm Isp 370s vac Isp TWR 17.54 LV-T45 320s atm Isp 370s vac Isp TWR 13.60 Aerospike 390s atm Isp 390s vac Isp TWR 25.49 LV-909 300s atm Isp 390s vac Isp TWR 10.20 First let's start with the poodle. Obviously with it's terrible TWR and excellent vac Isp it's intended to be used exclusively as orbital manoeuvring engine for spacecrafts. But why would you use it? Its little brother LV-909 has the exact same Isp performance in vacuum yet with better TWR. In fact if you cluster 5 LV-909 together you get an engine cluster with exact same mass and vac Isp as one single Poodle yet with 30N higher thrust. The only thing Poodle has against this 5 engine cluster is a bigger gimbal range, but are you really going to pay that kind of performance penalty for gimbal range on a spacecraft already with plenty of steering thanks to the command pod reaction wheel? But 5 LV-909 is going to be a bit unwieldy to install. But what if you replace that poodle with a LV-T30? You'll get: 1.25kg less mass for spacecraft (this is pretty big amount when you consider that's weight saved at the very tip of the rocket) 5N less max thrust 20s worse vac Isp no gimbling The way I figure, most small spacecraft don't need a gimbling engine since command pod reaction wheel provide plenty of steering. 5N of thrust is negligible and you're not firing the two engines long enough to have that 20s Isp offset that massive difference in weight. If you are actually going to fire engines in space and use up that much fuel you're probably better off with nuclear engines. So if the poodle can't beat two different combinations of engines in its role of spacecraft propulsion then what's the point of it? Now the mainsail, it has terrible atm Isp but excellent TWR, making it good for first stage engine to lift heavy lifters off the ground. But still, Aerospike has a TRW just as good yet with much better Isp, both in atmosphere and at lift off. A cluster of 6 Aerospike provides the exact same thrust as a mailsail yet uses much less fuel at all stages of flight. The only advantage of mainsail to Aerospike cluster is gimbling which can easily fixed by adding winglets/canards to the Aerospike cluster powered rocket. Alternatively the Aerospike cluster can be built by mixing in a few LV-T45, trading Isp and TWR for some steering. A mainsail core engine is terribly fuel inefficent if you keep it burning all the way from ground to orbit with it's low Isp and heavy weight, where as a cluster can shed outer Aerospikes and keep the center LV-T45s as it ascends and trade the now unneeded TWR for less deadweight. This is aside from the point that mainsail have to compete with SRBs (which have even higher TWR) for the role of liftoff engines. So with efficiency in mind, is there any point in using the two big engines?

Yes, it's a bog standard small spacecraft except with mod docking port at the tip. They really should focus on official docking support, it's the one feature I want more than any other

Orbital Propellant Depot Olympus with two visiting spacecrafts, made with Erkle and ORDA docking mods. You can get it here at: http://kerbalspaceprogram.com/forum/showthread.php/22560-0-17-Erkle-ORDA-Orbital-Propellant-Depot-Olympus I've currently got another Olympus in LKO waiting for a re-usable Mun lander to launch. Once that package is ready I plan to setup shop around Mun too.

If it's interplanetary travel you're looking for, I've been working on something too. In my oppinion though neither docking mods are stable enough to make interplanetary carrrier vessels like this practical, more so when you want to dock more than one ship to the carrier.

By popular request, Olympus - M: now without mobility enhancers. I've also switched first stage to the new large SRB (all other stage same). This ends up putting about 600L more fuel into orbit at launch.

Yes unfortunately mobility enhancer is a double edged sword. In the early prototypes the part count was even higher because I didn't use any ladders and it was all hand hold. I recently got myself a pretty powerful new desktop (i7-3820 3.6GHz, 16GB ram, GeForce GTX 660 Ti) and even then all hand hold prototype was a slide show at lift off. Swapping out as many handhold as possible for ladders and trimming the mobility enhancers to a minimum got the part count down by about 150 and made it quite useable on this computer but I would recommend users take off mobility enhancers if they prefer performance to convenience. Aside from mobility enhancers you could also take off ORDA fuel transfer system on the fuel tanks if you feel you are only ever going to do fuel transfer via Erkle system. You lose the ability to trim spacecraft by selectively filling fuel tanks and the ability to fuel transfer to stationkeeping but not docked spacecrafts. But these two capabilities would be pretty rarely used I imagine.

I've also attached a tanker rocket design. I use it to refuel the depot when it runs low. Each tanker refuel adds about 50% of the max capacity back to the depot (not included attached Apokee II tank capacity). That said if you have a really big spacecraft waiting in orbit that needs 3200L+ of fuel then it's probably not worth it to dock with the depot. For that kind of fuel requirement you're better off launching a dedicated tanker rocket specifically for that spacecraft. I actually have a 4800L to LKO tanker design as well. But it only carries 1100L of RCS fuel and it's pretty unwieldy. You'll have to be very good at docking to get that fatboy to link up to the target. If you run out of RCS fuel before you could dock that's 4800L of fuel in orbit wasted.

Imagine a world without gas stations, how far could you drive your car before you have to turn around and head for home? Until now, space exploration lives in just such a world. We got to the Mun and back only by kicking everyone out of the backseat and piling jerry cans full of fuel inside. A gas station in space – an orbital propellant depot allows us to reach deep into space in ways previously thought impossible. Research have shown that the majority of cost associated with spacecraft development is not in the spacecraft but in the development of the launch vehicle. And as we build larger and more capable spacecrafts the size of the launcher vehicle underneath must increase exponentially. A spacecraft, fully fuelled and capable of interplanetary landing and return will require a rocket at launch so massive it will border on the impossible. But what if we could launch this spacecraft without its fuel? Fuel often takes up as much as 90% of the laden weight of spacecrafts, if we were to launch a spacecraft ‘dry’ knowing its fuel is waiting for it in orbit then you would only need a rocket 1/10 or less the size of the original, or alternatively the same heavy lift launch vehicle could be used to launch a dry spacecraft ten times the size of a fuelled one, putting return trips to the outer planets within reach. To becoming a space faring civilisation we need orbital propellant depots, and now we have one. Orbital Propellant Depot Olympus features: 6400L of bipropellant and 2200L of RCS monopropellant storage capacity in orbit Six hybrid ORDA/Erkle docking ports for easy docking and fuel transfer Easy to fly HLLV, capable of reliably putting depot and about 3600L of bipropellant in orbit at launch Powerful on board manoeuvring engine, easily capable of transmunar injection Easy accessibility features, allowing anywhere-to-anywhere EVA for refueling ships without using EVA suit jetpack. T - 5: Turn on ASAS and throttle up T: Stage for initiation and hold down arm release, let the rocket go straight up T + 25: SRB separation T + 1:30: Outer liquid booster separation, rocket should be at about 9000m At 15000m, begin pitching down till you’re at 45 degree to horizon T + 3:14: inner liquid booster separation, depot manoeuvring engine ignition, begin pitching down to about 10 degree to horizon T + 3:53: core sustainer engine jettison, keep the depot’s own engine burning and pitch down to horizon Continue until orbit is achieved. Recommended LKO orbit for depot is 75000m (I choose this because this was the performance ceiling of my SSTO) After testing prototype with either Erkle's or ORDA's docking mod I came to the conclusion that neither were mature enough for a propellant deport. They each had their strength’s and weakness. The solution was simple: use both! The hybrid docking system that uses both mod takes advantage of strength of each and avoid the weaknesses. ORDA provides a very powerful guidance and navigation computer and RCS fuel transfer capabilities while Erkle’s system provides solid hard docking. The hybrid allows a semi-automated docking process: Fly the docking ship and make a rendezvous with Olympus using hohmann transfer orbit like usual Once you’re within 1km, jump to Olympus with [ ] key and turn on ORDA computer. Go to Rendezvous & Docking > ATT > VP, this keeps the nose of Olympus in the direction it’s travelling. Toggle ATT to OFF and roll the ship to orientate the navball to level with horizon and toggle ATT > VP back on, make sure your ASAS is off Jump back to the docking ship, turn on its ORDA computer and go to the Tgt tab. Select the vessel port and pick an Olympus docking port you want, the port numbers are: 1 fore (front) 2 starboard (right) 3 nadir (below) 4 port (left) 5 aft (behind) 6 zenith (above) With port selected, go to Rendezvous & Docking > DOCK > AUTO and hit Engage, turn off ASAS if on and turn on RCS The computer will start in ENTRY mode and fire RCS engine until Olympus is about 50m away The computer will then go into ORIENT mode and turn so the docking system on your ship is lined up with Olympus docking target, while this is happening right click on your Erkle docking port and turn on warp claw Wait till Approach Deviation is small (<1 degree on all three axis) and switch to Rendezvous & Docking > DOCK > ATTITUDE. This keeps your ship on the correct orientation to line up with Olympus docking port. Use RCS translate control to bring your ship in Once you close enough (about 7m from docking target) the warp claw tractor beam will turn blue and exert a slight pull on your ship. Turn RCS off and let the beam pull you in Congratulations! You have docked with Olympus Of course computer assisted docking is just the start. The ORDA computer uses a lot of RCS fuel during ENTRY mode that should really be done using the spacecraft's main engines. Once you become confident at docking recommended you do it manually to save RCS fuel. It's even possible to dock an Erkle-only ship to Olympus without ORDA assist at all. Using both Erkle and ORDA allows transfer of both fuel and RCS fuel. Olympus is fully rigged with handholds for easy EVA refuelling access. The refuelling process goes: To refuel main engine bipropellant, simply right click on the Erkle docking claw of the ship to be refuelled (this can be Olympus! That’s how it takes on fuel from tanker rockets) and click Refuel To refuel RCS monopropellant requires EVA. Do not EVA in a way so that any docked ship becomes un-crewed. For safety always use Olympus crew for EVA Take your kerbonaut and climb down to one of the two RCS tanks. Press G for grapple and you will notice a white line coming out of one of the machines labelled FT. This means you have taken hold of the fuel line. Press G repeatedly if you are near multiple fuel transfer system to cycle through to the one you want Climb down to the refuelling ship and go next to the target RCS tank that you want to fill up and press G again. This will connect the fuel line to target fuel tank. Switch back to Olympus with [ ] key and you’ll notice a new Fuel Transfer menu. Hit Transfer to being RCS fuel transfer Once RCS fuel transfer is complete, go back to your kerbonaut and go to the RCS tank that was just filled and press G to pick back up the fuel line. Connect fuel line to any other RCS tank that needs refuelling Once refuelling is complete, pick up the fuel line again and climb back to the RCS tank. Hit G (might need to do a few times) to place the fuel line back Climb back and reboard Olympus. Don’t worry about the bipropellant fuel transfer, the fuel flow will stop once it’s filled. Alternatively you can cut off early by go to the docked ship, right click on docking claw and stop the refuelling The SSTO in this example took on nearly 3000L of bipropellant and about 120L of RCS monopropellant. It went from running on fumes to having more than enough fuel to go to the Mun and back. After a big refuelling operation like this you will want to launch a tanker rocket to meet up with the depot to refill the depot tanks. The refuelling process is the exact same as this only in reverse with Olympus as the fuel recipient. Note that Olympus is equipped with ORDA Fuel Transfer System for both RCS and bipropellant fuel. Instead of using docking claw’s fuel transfer system you may wish to use ORDA system for bipropellant fuel transfer if you want to fill one tank at a time for spacecraft trimming. The fact that ORDA fuel transfer doesn’t require docking means that Olympus can actually refuel spacecraft without any docking ports if they can perform stationkeeping within 50m of the depot. Bipropellant fuel transfer using the ORDA system work the same way as RCS fuel transfer. There's very little point to have a propellant depot if you have no way of refuelling it once its tanks are empty. To support depot operation tanker rockets have to be regularly launched for top ups. Here's one I've designed: Exotanker tanker rocket Capable of offloading 3200L+ of bipropellant and 1600L of monopropellant to Olympus on a good trip, Exotanker is an expandable and reliable tanker rocket perfect for lifting fuel to LKO. Equipped with male version of Olympus's hybrid docking system to allow semi-automated docking it's also perfect for refueling spacecraft big enough to call for dedicated tanker runs. ORDA fuel transfer system allows refuelling ships without docking ports. Apokee II Crew Exploration Vehicle Small multiple purpose spacecraft perfect for crew transfer and rescuing stranded spacecrafts by bringing fuel to them. Apokee II is equipped with male hybrid docking system and ORDA fuel transfer system. Also useful to keep one docked to your Olympus class as a cheap way to increase depot fuel capacity. Dreamchaser II HTHL SSTO Fully reusable HTHL SSTO with male hybrid docking sytem, perfect for rapid crew transfer within cismunar space on the cheap. If you would like to design your own depot compatible ship remember to use ORDA Docking System (the male version) instead of ORDA Docking Target or Decoupler as Olympus itself is equipped with 6 docking targets. Aside from the .craft files, you will need to install these two mods for the two docking/refuelling systems to work: Erkle Mods - Warp Capable Docking Clamp - v0.5 x1 http://www.boxtin.co.nz/downloads/ErkleWarpClamp_v5x1.zip Orbital Rendezvous and Docking Assistant http://dl.dropbox.com/u/105710304/ORDA%20beta1.zip

I did some research, current NASA requirement for astronaut height is between 62 and 75 inches, or 157.5 cm to 190.5cm. Pete Conrad is 169cm, so I guess despite what he says he\'s not that short after all.

But both NASA and KSP have female astronauts... Fun fact: All the Vostok astronauts were pretty short, Yuri Gagarin was only 157cm. When you think about it there\'s every reason to pick short astronauts, they can move around in their phone booth of a spacecraft easier and they weigh less. Scale that up with their spacesuits as well and that difference becomes non-negligible.

Average human height is not 180cm, it\'s more like 165-170cm. Neil Armstrong was 180cm and was considered tall among the Apollo astronauts, enough so that Pete Conrad\'s first words on the moon was 'Whoopee! Man, that may have been a small one for Neil, but that\'s a long one for me.'

It\'s actually very easy. The jet engines in KSP (particularly that turbojet) have physics defying high thrust to weight ratio compared to the rocket engines. http://kerbalspaceprogram.com/forum/index.php?topic=12625

I think it\'s to do with fuel tanks. Engines only work if they are attached to something above them that can feed them fuel, fuel lines don\'t count for this purpose. Make sure your engine is attached under a part that\'s either a fuel tank or something that says 'fuel crossfeed capable'.

Oh but aerospike engine exhaust should be yellow not blue. That aerospike engine is pretty much strictly first stage only since you can\'t attach decoupler below it (and first stage engine is kind of the point of aerospike nozzles given its ability to burn efficiently at wide range of attitudes). First stage LFEs almost always burn hydrocarbon fuel like RP-1 which means their exhaust will be yellow due to unburnt carbon.

Little mouse? In reference to the faint cometary tail it develops on closest approach to Kerbol?

You could just wait till Minmus is in such a position that when you reach your 46400km apoapsis it will be there right on the ascending node / descending node above the Kerbin equatorial plane, this will happen twice (and so two launch windows) per Minmus month. I think adjusting your orbital inclination to match Minmus in LKO before trans-Minmus injection is actually really inefficient. Maximum efficiency of inclination change is achieved at apoapsis right? So if you want to match Minmus\'s inclination it\'s actually better to perform the inclination change at the 46400km apoapsis than it is in LKO. If it was NASA planning a manned mission though they will probably go for inclination change in LKO because it\'s safer. If the inclination change fails for any reason in LKO then the spacecraft could fairly easily be deorbited to bring the crew back or a rescue mission could be mounted since crew will have enough provisions to survive for days/weeks in orbit. If the engine doesn\'t work at 46400km for the inclination change then the crew is going to die a slow and painful death in Kerbol orbit.