The Big Kerbal Space Program Thread - (was: a mission to send a Spaceplane to moon..)

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Jan 17, 2009
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Sometimes KSP, or Kerbal Space Program is mentioned here on TRF. A recent thread here:

And an older one here:

Kerbal Space Program Website:


I'm posting this thread to give an example of a rocket designed for a purpose, with some details about the rocket and the mission. it's not the most sensible rocket, since there is no good reason to send a winged spaceplane to a moon with no atmosphere, but I wanted to challenge myself into doing just that with a newly built spaceplane.

So, those who know nothing about KSP may get some useful insights, even though some of this is more advanced stuff that you do not need to know to start playing the game. You do not even need to fly into space to have fun……but it's more of a challenge to get into orbit and go farther. For those who have done KSP, a lot of this will be familiar.


I've done some playing of Kerbal Space Program this week. I had made a "Spaceplane" that could make orbit all by itself (SSTO), due mostly to a theoretical Jet and Rocket engine that in jet mode can use fuel only, using air for oxygen, until it gets high enough that the air is too thin, then it switches over to being a rocket engine, using onboard liquid oxygen. The plane I made can make orbit with fuel to spare. In theory I could use it to fly to a space station in orbit, or go rendezvous and dock with some other vehicle in orbit. But I do not have a mission in mind for that.

For the heck of it, I decided to fly it to the Mun. That's the name of Kerbin's largest moon, Mun. So I gave it some landing legs for a vertical landing, and extendable ladders. Most importantly, I built a rocket under it to be able to get it into Kerbin orbit, take it to the Mun, get it into orbit around the Mun, and de-orbit it almost all the way to landing before dropping the last stage so it could land upright by itself.

After lot of the usual trial and error with tests of a new launch vehicle for it, it ended up as a very capable vehicle. It might be able to fly to Duna, the game's equivalent to Mars, but it would never be able to get back (Duna's air is too thin for the wings to be of much use for a safe landing and it has no oxygen for the engine to use in jet mode so it might be able to land vertically on rocket power but never get back).

With the performance being far more than needed, I could have given the final transfer stage about half the fuel capacity for a Mun trip, using a smaller tank. But that's OK, that leaves some room for future capabilities. Such as giving that transfer stage, and spaceplane, the capability for docking, so some future mission could get into orbit around the Mun, the spaceplane undock, land itself, take off, dock with the transfer stage, then fly to Minmus (another moon that is in a bit higher orbit, with a bit less gravity), transfer fuel from the transfer stage to the Spaceplane, undock the spaceplane, land on Minmus, take off, dock with the transfer stage, and fly back to Kerbin. Maybe the transfer stage would not have enough fuel to do that….but it could have more fuel tankage added….thanks to the launch vehicle having a lot of performance.

Of course if I wanted to go to both of those moons, the gimmick of the spaceplane that does not use that great engine in jet mode, and not use the wings, until getting back to Kerbin's atmosphere, is not really worth it. So I'd swap out the Spaceplane with a more efficient lander, maybe one carrying two or three crew members rather than just the one. And actually in the past I tested out my favorite lander design (Synchronicity) by doing a mission to Minmus and then to the Mun, then back to Kerbin. But that lander dropped tanks and engines along the way, no Apollo-like orbital re-docking with a transfer stage.


Anyway, back to this new launch vehicle. The main core stage uses 5 liquid engines, the lower part of its tank is orange (I could have used one big engine, but the big engine is not as efficient as the ISP of the 5 clustered engines I used). It has two liquid fueled boosters, which also have an orange tank as part of it, plus some big fins to make it aerodynamically stable due to the plane's wings on top. The liquid boosters have 5 engines in the bottom plus 2 more on the sides. The main core has fuel lines running from the outer booster tanks so that the main core can use fuel from those tanks and not use any core fuel until the side booster tanks run dry.


It also uses two big SRB's, which are black and white. Their thrust level is so high that the whole vehicle does not need for the center core engines to ignite at launch. So only the SRB's and outer liquid boosters burn for launch. And after it gets moving fast enough, the liquid booster engines are throttled down to optimize efficiency, so as not to exceed terminal velocity.


The SRB's burn out 52 seconds into the flight, at 6.5 kilometers (Kerbin is smaller than Earth, and it's atmosphere extends only to 70 km) They are jettisoned and separation rockets help push them away to avoid colliding with the core. They also deploy parachutes and landing legs, so they can land back at KSC (Kerbal Space Center) for re-use.


Also when the SRB's burn out, the center core's 5 engines ignite and use fuel from the outer liquid booster tanks.


The vehicle begins to curve from vertical to begin to increase the horizontal velocity, at 10 km up. This is another basic part of flying into space, and learning the tradeoffs of the right kind of curving path to fly to get into orbit the most efficiently. So that either you have more Delta-Vee left to use once you make orbit, or in the case of a marginal rocket… to make orbit at all. If you have a rocket that has 104% of the Delta-Vee to make orbit, and you fly it inefficiently so that it wastes 6% of its fuel, you're not going to make orbit.

So, this rocket curves more and more as it gains altitude, the air gets thinner, so it is more efficient to fly at shallower angles to increase horizontal velocity. Along the way, the liquid boosters run out of fuel and separate, at 2:20 and 41 km up.


Eventually when its Apoapsis (apogee) is projected to be at the desired orbital altitude of 100 km, the engines are shut down. For this one it is 3:16 into the flight, at 74 km. Then it coasts until it is nearly at Apoapsis of 100 km, coasting a sub-orbital arc. . Shortly before apoapsis, before it stops coasting up and starts to fall down, it is aimed horizontally and the engines fireat 4:28, 98 km up. The firing is to increase the horizontal velocity, to stretch that sub-orbital arc into an full circle that is larger than the diameter of the planet, plus atmospheric height, so it will reach orbit. Of course that is not just for this ship, or this game, it's true for anything going into orbit, it needs a final burn of some type, but the path used varies a lot depending on the vehicle.

Burnout at 6:00, in this case an orbit of 101 km by 98.9 km.

With the vehicle finally in orbit, the core still has LOTS of fuel in it, a bit over half. That is enough fuel left in the main core to send the vehicle from Kerbin to the Mun, and retro burn to begin to get into orbit around the Mun before that stage runs out of fuel.



I'm leaving out the orbital mechanics part of how to actually get to the Mun, just covering the vehicle. Once the core runs out of fuel, it has put the vehicle into an elliptical orbit around the Mun. It is jettisoned, and the transfer stage takes over.


The transfer stage has a nuclear engine in it (NERVA-like), with an ISP of 800, more than double the best conventional liquid engines in the game. If I were trying to build a more efficient rocket, I would have reduced the fuel in the core stage and given the transfer stage more fuel, so that the more efficient nuclear engine could do the work of getting from low Kerbin orbit to the Mun. And indeed some of my better launch vehicles often have very little fuel left in the stage that gets the vehicle into orbit, then is jettisoned (I sometimes fire the engine in a jettisoned stage to make it de-orbit, it does not take much to "nudge" the orbit enough to cause it to dip into the atmosphere.

Sometimes a stage with nuclear engines is fired before reaching orbit. It is the most efficient, but the nuclear engines have very low thrust, part of the tradeoffs. So if the stage with nuclear engines takes over with a LOT more velocity needed achieve to be able to make orbit, it is not going to accelerate fast enough to reach orbit before it begins to fall back into the atmosphere. Possible solution, add more nuclear engines, for more thrust. But the engines are VERY heavy for the amount of thrust they produce, so it is not worth adding more nuclear engines just for the sake of trying to reach orbital velocity soon enough (as far as radiation, well, uh, the Kerbals apparently have no problem with radiation. Though I know a few players who design their ships in a way to minimize radiation effects, of their own choice).

OK, so, back to the Mun, the Spaceplane with nuclear powered transfer stage. The engine fires to change the orbit from elliptical to circular, at an altitude of about 10 km. A landing site is chosen and the nuclear engine fires to begin the decent, much like the Lunar module of Apollo. It slows the horizontal velocity, and the ship begins to descend at more and more of an angle. Eventually it is almost vertical, less than a kilometer above the surface. The transfer stage is not built to be able to land, it has no legs (though it could have). So, it is being used as a "crasher" stage, like the Russians were going to do with their N-1 rocket Lunar Lander, use the crasher stage to retrofire nearly all the way down, then jettison it to crash when close to the surface so the lander only has a short time and distance that it needs to burn its engine to land.


The Spaceplane is on its own now, firing its engine for the last few hundred meters and the landing legs are deployed. It lands slowly, fortunately on a reasonably level surface.


The engine shuts down and it's safely on the Mun. The Kerbonaut onboard has the ladders deploy, climbs out of the ship and down the ladders to set foot on the Mun. He plants a flag to show "been here, done this" , smiling for a photo taken by means unknown, and then gets back aboard.


He plans out the new launch flight path and takes off. With no atmosphere, it does not need to go very high to get into orbit, 10 km is plenty. And once it gets a bit of initial upward velocity, it can be pointed horizontally the rest of the way. it almost looks like it is "flying" like a plane across the Mun, but the wings are not doing anything since there is no atmosphere.


Once in circular orbit at 10 km, he waits for the orbit to be at the right point for do a burn to return to Kerbin. He fires the engine to accelerate from the Mun, but the position of the Mun's orbit he is in will also mean that the ship is in effect doing a retro burn relative to Kerbin. The end result is an elliptical orbit that dips down to a very low Periapsis, that is almost into the atmosphere of Kerbin.


He does a tweak burn that will cause the Periapsis to be about 40 kilometer above Kerbin's surface, 30 kilometers inside the atmosphere, Fuel is getting low, at least the liquid oxygen portion is, there is not a lot left for firing the engine in rocket mode in space. The Spaceplane will do an aerobrake maneuver, slowing it down but skipping back out of the atmosphere so that it the next Apoapsis will be only a few hundred km above Kerbin. He does a tweak burn to make the apoapsis a little bit closer to Kerbin, so the apoasis after the aerobrake will be about 180 km. Then he sits back and waits to coast back to Kerbin, and finally into the atmosphere on the night side. During the peak of the aerobraking, the plane glows orange-hot, then skips out of the atmosphere, to coast to a apoapsis of 180 km.


If he does nothing, the plane will re-enter and land a couple of thousand km short of KSC. So at apoapsis he does a burn to raise the periapsis to above 70 km so the plane can get into an orbit. It does. Then he finally makes a retro burn to bring the plane into KSC. But the oxygen tank runs out a bit short, the plane will overshoot KSC by 20 km, over the ocean. The space plane does not have a parachute (there is a mod one can add that let Kerbals have a parachute), and won't ditch safely in water.

But, the plane does have wings, that was the reason to have them. But it is so high, and it cannot get a big enough "bite" into the atmosphere to do "S" turns like the shuttle did, that it can't shorten the distance it flies until it has gotten down to about 10-12 km up. So, it overshoots KSC.


It finally is in enough atmosphere to turn around and glide back. But now it is too low to glide back. Well, I said it had run out of…. oxygen. But it still has a reserve of fuel which the engine can burn in jet mode. PLENTY of fuel for jet mode. It only needs about 5% throttle to hold the right descent slope to make it to KSC.


Hmm, some weird object flew past a minute ago, what was that? And then, holy ….. the right forward leading edge of the wing has come off….and now I realize the object from a minute ago was the left front leading edge!


Well, this RARELY happens but I was doing a lot of saves and playing it over a few days. So, those parts…. fell off, at almost the worst time coming in to land. Without them, the Center of Pressure is more to the rear, so the plane wants to dive. I have to keep using a lot of up elevator. I can't adjust the pitch trim (It is possible but I so rarely need to and it has been so long that I forgot what key combo to use), so I just fly it anyway. It's a close call but it does land safely on the KSC runway.


So, the mission completed safely. The Spaceplane will need some repairs but is reusable. And the SRB's are waiting to be retrieved and refurbished.

Of course I didn't put hundreds of dollars into that mission, so I guess it was meaningless? Nope, way more meaningful than throwing away a few hundred dollars in Vegas. It was fun, and challenging. Of course I ended up doing things that a person does not know how to do when they first start to play KSP. But it's not that hard to learn. Of course, I also chose what I wanted to do, for various reasons (in this case, a silly premise of a winged spaceplane to a moon, then seriously doing it). That's part of what makes it so interesting since there are so many things to try.

There is almost no "wrong" way to do it. Except for when I see people just crash and crash them pretty much on purpose with crew onboard. That's disturbing. Yes, its only a game, no "REAL Kerbals" are killed playing the game. But good grief, the ships can be unmanned (unKerbaled) if someone just wants to do a bunch of wild stuff that crashes and blows up rather than actually trying to learn how to make the rockets fly right. And i've made my share of crazy rockets, and have "killed" many many crews, but never any crewed ship crashed on purpose.

I have posted more images on this vehicle's mission here:

Also, there are imgur albums for some of my other missions and vehicles at these links:

Eve & Gilly mission:

Moho missoon:

Eeloo mission:

Various KSP rockets on these other albums:

Also,. I highly recommend Sport Rocketry Editor Tom Beach's KSP reports:

And there are bunches of KSP youtube videos by Scott Manley:

- George Gassaway
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Nice mission report GG.

I'm thinking about doing some mission reports of historical or alternate historical flights.

That is brilliantly insane!

It never occurred to me slap extra engines on the side of a tank.
You may not have put a lot of money into it - but what about time? How long does it take to put together and execute that kind of mission?
Everyone, thnaks for your comments.

You may not have put a lot of money into it - but what about time? How long does it take to put together and execute that kind of mission?

I mentioned the money part as a reference to another recent KSP thrad where someone said they saw no purpose in it since it didn't cost hundreds of dollars a flight like their rockets do. I bought KSP 2 years ago when it was $18, and updates are free. Even now at $30 it's well worth it, it's advanced a lot more in those 2 years.

The time well, it depends on the complexity of the planed mission. My most complex single spacecraft mission was one to Moho, their Mercury. I used my Synchronicity lander design, optimized for that mission, carrying 4 new small unmanned lander probes. And needed a bigger new rocket to get it on its way. I spent a lot of time on the lander probes, mostly finding out how to make them fly independently. The most complex ever was a mission to Eve and Gilly, sort of like going to Venus if Venus also had a very small moon with very weak gravity. Eve has almost twice the gravity of Kerbin and 5 times thicker atmosphere that is 98 km high, so it is the hardest planet to be able to get back from (Not counting Jool, their version of Jupiter, extreme gravity and liquid surface which I do not think anyone has been able to get back from unless they use a bizarre mod like a helium balloon). Anyway, spent a lot of time working out a lander that could take off from Eve and get back into orbit. It was so difficult to do that the lander barely had any fuel left after making orbit. I used a "unique" way to save mass on the "capsule", which allowed flying two Kerbals into orbit when nobody else had ever flown back more than one


So that required two launch vehicles, one to fly the lander (and a base camp habitat) to get there first for exploring.


Then a second rocket to fly my Synchronicty lander that would rendezvous with the Eve lander once it got back into orbit. Then the Synchronicity lander went over to Gilly and set up a base camp and leaving a couple of Kerbalnauts there, before returning. I spent two weeks on and off on the lander that could fly back from Eve, a lot of trial and error. Once I finally got the Eve lander to be able to get back into orbit, then I could finally plan to do an Eve mission.

For this week, the SSTO spaceplane took less than an hour, maybe 30 minutes. I was surprised that it worked so well right off the bat. Had more fuel left than I expected, and handled well as a plane. Usually there's a good bit of tweaking needed.

When I decided to make a launch vehicle t fly it to the Mun, that took a few hours one night. Some trial and error to work the bugs out, and get the "staging" sequencing right (not exactly staging in a drop of stages sense but the sequential order of events to be carried out one step at a time. Even deployment of parachutes is a "staging" event).

The actual mission to the Mun and back took less than an hour. The game lets you fast-forward, so you do not have to spend hours waiting for a ship to coast from Kerbin to the Mun. You can fast forward coasting from Kerbin to close to the Mun, then stop and prepare to make some flight path tweaks, then fast forward a bit to get almost to the point where you need to make a retro burn to go into orbit around the Mun. I heard of someone who flew a mission "real time" to the Mun and I think he launched on a Friday night and landed on Sunday night. He used an alarm timer to let hm know when it was time to get back to the game for an important maneuver.

Last night I made up a new lander, a pretty efficient one which can do a flight from Low Kerbin orbit to the Mun, then to Minmus, and back to Kerbin, without any stages. It does drop some fuel tanks along the way, but otherwise only uses a single stage launch vehicle to help boost it into Kerbin orbit. It has 4 crew members.

I'll probably post a mission report for that one too. Should I add the report to this thread or make a new thread?

- George Gassaway
I have the demo version of KSP. It's awesome!! I can get to the Mun but I can't get back... Keep it up, it's great when people post about KSP.

I've started a photo album of my KSP misadventures. The only mods I use are KW Rocketry (for the Saturn V class boosters and aero shrouds) and MechJeb (for recreating a mission after I've flown it once to see just how inefficient I was...). I tend to fly KSP as close to current tech as possible (ie no nuclear engines, long range missions have to have a 'habitat module' - not just a flight deck - on the ships, etc). KSP does not as of yet monitor things like expendables (oxygen, water, food) nor are there consequences for atmospheric reentry (ie heat effects are visually modeled but no damage modeling) or excessive G loading (other than trying to go sideways under thrust).

Here is a recreation of the Apollo moon missions:

Some selected pics:

Look familiar?

Shroud jett

About to land

Planting the flag

Hey Jeb, lets see what this thing can do...

Ascent stage

Heading home

Safely parachuting to Kerbin

Very nice mission and report! Spaceplanes are very cool. I haven't returned from eve yet, but that's one of my next challenges. Also, nice apollo mission FC!

This was a reusable spaceplane I flew to minmus earlier today (second moon of kerbin with low gravity). It uses a single turbojet engine and a single NERVA. With lots of air intakes it can reach almost orbital velocity (which is much lower than earth orbital velocity) before starting the rocket. It's a bit unrealistic but very fun to fly. I use a mod called mechjeb that includes lots of orbital information and autopilots, although I flew the mission manually and just used the mod for information.



I forgot about this's a small set of a mission to Duna (Mars), again trying to use relatively realistic limitations like chemical engines, habitat modules, etc:

The space station where the Duna One ship was built (you can see it in the mid left of the screenshot). Multiple launches were required to build the station, and the ship. You'll note habitat modules, a single manned lander on the Duna One ship, and a one-man spaceplane docked at the bottom of the station.

Inbound to panels retracted.

One large step for Kerbalkind... The side pods of the ship contain the parchutes that helped slow down the ship for a soft landing.

Ascent stage redocked with Duna One...note the side pods have been jettisoned and 2 of the fuel tanks on Duna One have also been tossed.

And a safe return to Kerbin.

More alternate historical missions:

What if the Russians were on the verge of landing on the moon, and the Saturn V wasn't far would we go to try to get there first.

The One Man, One Way Moon Landing.

And doing it in Kerbal Space Program:

Here is the rocket needed. The picture doesn't show it, but it is only as wide as the Service Module in the Saturn V pic I posted above.

The spacecraft...note the transfer stage is basically the same fuel tank/motor combo as the Service Module from the Saturn V.

Detached from the transfer stage in descent to landing. The parachute was jettisoned...after all, he isn't going to need it now...

Looks happy...wonder how long he'll stay that way until they can get him back!

And an alternate ending where he doesn't see the Mun shelter and decides to just swing around and come right back without orbiting or landing.

Thanks George. I caught the prior thread reference - I had been reading that one, too. Just curious as to the time input - thinking about getting it for one of my Boyos.
My problem with the KSP is that it is COMPLETELY UNREALISTIC!!

Sure, they may have modeled the physics OK, but where's the realism? I mean, all the political wrangling to get a design through the political process, defending it against harm whenever there's a hiccup or cost overrun, the good old boy network for getting things manufactured by the "right" contractor, shifts in policy with new administration, political backstabbing... navigating these issues is the real challenge to a space program.

<OK, I'm done with my rant, and for the record, the only reason I don't use KSP is that I'd get so hooked I'd have to give up on family and job and such>
My problem with the KSP is that it is COMPLETELY UNREALISTIC!!

Sure, they may have modeled the physics OK, but where's the realism? I mean, all the political wrangling to get a design through the political process, defending it against harm whenever there's a hiccup or cost overrun, the good old boy network for getting things manufactured by the "right" contractor, shifts in policy with new administration, political backstabbing... navigating these issues is the real challenge to a space program.

<OK, I'm done with my rant, and for the record, the only reason I don't use KSP is that I'd get so hooked I'd have to give up on family and job and such>

Heh! Maybe they can add that in career mode...

It's funny, but career mode has turned out to be pretty interesting. Now you have a budget, that you can increase by accepting contracts. You also have science and reputation. As you get more science, you can advance up the tech tree, and reputation offers more contracts. And you can vary how much you are willing to exchange one of the three variables for the others. Early on can be challenging when your tech tree is limited.

The thing career mode doesn't have is something that was in an old strategy game - Buzz Aldrin's Race Into Space or BARIS for short. It was a computer game based off the old Liftoff! board game. You played as either the chief administrator of the US or USSR space programs, and you were trying to get to the moon first. Advancing up the tech tree required spending money on hardware, and research. Your astronauts also cost money to recruit and train. Budgets and hardware reliability were influenced by success or failure. Political points helped...being first with an unmanned probe to other planets could help with the budget. Every flight had multiple events that were influenced by your probabilities ... the more reliable the hardware, training, etc, the less likely of a failure.

Here's a free version of it you can play, basically includes everything of the original except the video:

Anyway, there was still the random chance factor ... even if you thought you did everything right, something could still go wrong.

KSP career mode doesn't have that 'random dice roll' factor...I always thought that an 'expert' level of the career mode would be interesting. There would be a 'dice roll' on the parts of a rocket, where something randomly could go wrong. You can research that part to decrease the chance of failure...but that costs money. Also, and this would be tough, make committing to the launch permanent. Basically, as soon as you hit the stage button to fire the engines, that launch can't be scrubbed (scrubbing would be a reputation hit, plus some money would be lost). You live with the consequences...good or bad. Every launch becomes a nail biter hoping you fly it right and that something critical doesn't fail or that you didn't make a major mistake on the design. Strategic and tactical in the same program.

My problem with the KSP is that it is COMPLETELY UNREALISTIC!!

Sure, they may have modeled the physics OK, but where's the realism? I mean, all the political wrangling to get a design through the political process, defending it against harm whenever there's a hiccup or cost overrun, the good old boy network for getting things manufactured by the "right" contractor, shifts in policy with new administration, political backstabbing... navigating these issues is the real challenge to a space program.

<OK, I'm done with my rant, and for the record, the only reason I don't use KSP is that I'd get so hooked I'd have to give up on family and job and such>

Here ya go...,36148/

Later! OL JR :)
Everyone, I'm really pleased at all the comments and many people's own flight reports and examples of their own KSP missions and vehicles.

Thanks George. I caught the prior thread reference - I had been reading that one, too. Just curious as to the time input - thinking about getting it for one of my Boyos.

The time input, well, it's dependent a lot on how adventurous and complex of a mission one wants to do. And that often involves learning some new aspect which take time, then in the future you know how to do that so it takes less time next time around.

For getting started, totally different thing. It only takes a few minutes for the carnage to begin.

Uh, I mean for the learning to begin. :)

You build a really simply rocket, one capsule, a parachute (or chutes), a decoupler ring (so the capsule can separate from the rocket), a fuel tank under the decoupler ring, and an engine of suitable thrust under the tank (Optimum thrust to weight ratio at launch is 2:1, though for a beginner anything over 1:1 will work to get into the air). Launch it and see hat it is like to fly, how to steer it (press "T" to make the stabilization system, SAS, try to hold position). After it burns out and reaches apogee, separate the capsule and deploy the chute. If you really want to save hardware, give the rocket a couple of side chutes that are set to deploy when the capsule is decoupled

From there, then copy the rocket design and add a stack decoupler to the bottom of the engine, and add another fuel tank, and an engine with enough thrust to be able to lift the whole thing properly. Now you have a 2-stage rocket which might be able to reach orbit, but probably not unless you stumbled onto a really good choice of engines and tank sizes for the 1st and 2nd stages. A neat fun way to go is to add decouplers to the sides, to add side boosters. Not solid boosters, as that are usually not so efficient. But two side boosters that are copies of your lower stages. Arrange the fuel lines to run from the side booster tanks into the core tank, this will allow the center engine to get fuel from the side tanks. Arrange the "Staging list" to make the side boosters jettison on the next staging step, so when they burn out you press the space bar and the side boosters drop off, as the center core keeps burning with all that fuel it only now started to use. Such a rocket is very often capable of making orbit.

But you have to learn how to steer a good flight path, let it climb vertically to about 10 kilometers or so to get into thinner air, then tilt horizontally more and more as it gets into thinner air, ultimately horizontally. You look at the Map view to see the ballistic arc, ad whatthe projected apoapsis will be. Try to get the projected apoapsis to be about 80 km. Then shut down and coast nearly to apoapsis, then with the rocket pointed horizontally, fire the engine again and look at the map view as the ballistic arc gets wider starting to stretch around Kerbin. Then it becomes a circle with the periapsis listed. (lowest part of orbit). Keep buring until the periapsis is at least above 69 km (atmosphere height), then you are in orbit. I mentioned going for an apoapsis of 80 km rather than 70 km to give a bit of margin for error in trying to make orbit, though of course it takes a little bit more fuel to do that.

Once a person can fly into orbit, they've achieved the biggest milestone that a beginner can achieve. Well, until they want to go to the Mun (and back), and then other planets (and back).

BTW - Among the "stock" rockets, my favorite is the Kerbal-X. It has 6 side boosters (liquid) that are arranged in pairs, to drop off. The fuel lines are daisy-chained so that the whole first stage (core and six boosters) use the fuel from two boosters. Those two run out of fuel quickly, then it is time to drop them. Then the rocket uses fuel from the next two boosters, then drop those off. Then the last two boosters ue up their fuel, and those are dropped. This daisy chain method of having the whole rocket share fuel from sets of tanks that are dropped in sequence is called "asparagus staging" in KSP. It's the most efficient way to do a rocket, not just in the game, but for real. Unfortunately nobody has developed real-world technology to allow for such fuel share transfer, although I do not think it is far-out sci-fi as much as no company committing to develop and perfect the technology. After all, the Shuttle ET "shared" its fuel with the orbiter's main engines.

Anyway, the Kerbal-X is a great rocket to learn with, before trying to do a "serious" scratchbuilt rocket to try to fly into orbit with. Note I am not saying the idea of the game is to be "serious", it's to have fun. And some of that is fun in doing crazy rocket stuff, and other parts are fun to try to achieve a chosen objective. Though in career mode, yeah, not so suitable for crazy rocket stuff.

I still have not done my "real" mission with a new lander yet. I got bogged down into perfecting a launch vehicle for it, with a couple of massive design changes after each was nearly complete. I might finally fly the mission later tonight then I'll post screenshots and mission report Monday.

- George
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Just finished a mission to the moon Tylo. Tylo has 8/10ths earth gravity with no atmosphere, so it's quite hard to land on. I have landed there before but this was my first time landing there with no autopilots. I had a transfer stage to bring the lander to low Tylo orbit and a small return stage that brought Jebediah (one of the Kerbals) and the capsule/ central stage from the lander home to Kerbin orbit, where a spaceplane was launched to return the Kerbal.

If anyone wants I can post the whole mission album and/or craft file, the album is about 30 pictures.





SCrocketfan...nice! I haven't landed on Tylo yet, and a save game where I was slowly colonizing the Kerbol system finally just became too incompatible with all the updates. Plus my ship building is slowly getting more refined, so I find old designs to be...kludge-like.

GG, sorry for hijacking your thread...hope you don't mind us turning it into the KSP missions thread.

Here is a KSP mission building a rocket using the Direct Ascent profile:

A note...I found my KSP LOR Saturn V had a lot of wasted fuel when I flew it correctly and efficiently, so I cut the size down closer to have less excess fuel available. This will be the baseline Saturn V for future 'Apollo Applications':

Here is the 'Nova' for the Direct Ascent profile. Note it isn't that much bigger than the Saturn V. The Direct Ascent lander really wasn't much heavier than the CM/SM/LM combo of the LOR...which wasn't true in real life. I suspect it's because the parts I used in the LM for the LOR profile are rated (with the appropriate mass and structural beef) for atmospheric flight. So, here the Nova isn't much bigger, verses the actual Nova had it been built would have been monstrous (assuming a derivative of the Saturn C-8), roughly 11,000,000 pounds with eight F-1 engines in the first stage verses the Saturn V at 6,600,000 pounds with five F-1s.

On the Mun, note how tall it would have been (the landing stage/SM/CM combo):

And liftoff back to Kerbin:

What if NASA wanted to use Gemini for the first circumlunar flight:

The idea was to use a Centaur upper stage send the Gemini capsule on a free return around the moon. In the diagram, you can see that it would be an 'eyeballs out' type TLI burn.

Here is my KSP version of a simple Titan II. It barely has enough performance to get a basic Gemini capsule or a Centaur stage into orbit.

And the Centaur/Gemini docked nose to nose, brought up in two separate launches, just before the Centaur fires up for the TLI burn.

The combo rounding the back side of the Mun.

And the capsule, post SM separation, just about to reenter the atmosphere after it's historic circumlunar flight. Some KSP veterans maybe be wondering why I'm using a one man capsule and lander capsule tied together to make a two-man spacecraft verses using the stock included two man container. Mainly, aesthetics...I wanted my capsules to roughly mimic the relative sizes and shapes of the actual equipment used.

I finally flew a mission with the new Quad Lander. Attempting to fly to the Mun, then Minmus, and back to Kerbin, with 4 crew members. Too late to prepare screenshots and write it up tonight. Will post sometime Tuesday.

Here's two teaser screenshots of the early prototype Quad Lander, with the Spaceplane next to it.

- George


While I do enjoy pushing the limits with HPR, I also thoroughly enjoy playing KSP. I don't really get the whole "there's no risk since there's no money involved" thing. In fact, I feel like it is MUCH more difficult to be good at KSP than it is to be good at HPR. KSP is about as good as it gets as far as simulating real life astrodynamics and space launch vehicles. Lately, I have been moving towards more realistic mission scenarios and trying to do things as efficiently as possible, (this might help me when I have to take astrodynamics in two semesters). Here is a picture of one of my latest efforts, a small comm sat pretty close to GSO (I was a couple dozen meters off). Getting there was really tough using only 1.25 meter parts, but once I got there, I actually had enough fuel onboard the second stage to fly back and land F9R/grasshopper style!

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For any of you interested, the rocketry and astronomy club I am part of at my university (Iowa State) is hosting a KSP competition with an open division that anyone can enter. If you are interested, sign up here:

By the way, the challenge is pretty difficult.

Manny...:point: Introduced me to KSP last year at Airfest and, I had sooooo...much fun perfecting the art of Ker-Poofs, Ker-Bombs and, especially Ker-Splatz!
I'm glad too see one of us (at least) has matured over time. ;)
It's a neat little computer game!
Here's the flight of the Quad Lander.


The only engine it uses is the LV-N nuclear (Nerva) type engine. It weighs 2.25 tons, and only provides 60 kiloNewtons of thrust. By contrast, the first stage core uses five non-gimbaled LV-T30 engines that weigh 1.25 tons producing 215 kN thrust and four LV-T45 engines that weigh1.5 tons and produce 200 kN of thrust (those are gimbaled). The T-30's and T-45's had an ISP of 320 at sea level and 370 vacuum, among the best engines to use for getting off the ground. So, while the nuclear engine produces a lot less thrust and weighs more, it comes into its own for flying in space, because its vacuum ISP is 800 (Sea level ISP is a paltry 220).

So, one objective of this lander was to make it light enough so it would be able to land on the Mun with only the 60 kN thrust level of the nuclear engine.

The choice of 4 crew members was just that, a choice to do something new. I had not made a lander before that was designed to carry more than 3 crew members. Although for the Eve mission it did carry a Habitat module with two more crew members aboard, but those two were left behind on a new base. So, I've never tried to get more than three back.

The crew members each have their own capsule, the Mk1 Lander Can. Those weigh .66 ton each, while the Mercury-like Command Pod Mk1 weighs .84 ton, so .72 ton was saved, a total mass of 2.64 ton for the four. That is a lot lighter than the command pods that carry three crew members, the Apollo CM-like Mk1-2 pod at 4.12 tons and the Shuttle orbiter cabin-like Mk3 cockpit at 3.62 tons.

Of course the Quad Lander is not very aerodynamic. Neither was the Lunar Module. But unlike the Lunar Module, this lander re-enters the Kerbin atmosphere. Well, as the saying goes, that is "very Kerbal". The game does not yet cause vehicles to burn up on re-entry, and there are many very draggy launch vehicles that are used since the game does not realistically simulate drag as far as frontal area is concerned.

The fuel tanks are located in several locations. Four are in an "X" pattern near the top, mounted horizontally. Those are jettisoned in pairs after their fuel is used up.

Four are under the Lander Cans, and drop off when their fuel is depleted. There is also a central small tank set above the nuclear engine indeed the ship was built around that tank. That tank is pretty much the emergency reserve, all other tanks jettisonable.

The Quad Lander mass is 15.9 tons. By comparison the Space Plane mass is 11 tons. Of course the Space Plane is SSTO, it can fly into orbit all by itself. But to get to the Mun it had to be carried almost all the way, not igniting its engine until a kilometer above the Mun. the Quad Lander&#8230; cannot even take off from Kerbin's surface, but once it is delivered into orbit, it can fly itself from there, without any other stages.

Now for the launch vehicle. I wanted something that was not as massive as the one used for boosting the Space Plane. Of course, the rocket for the Space Plane was overkill, and took the plane to the Mun before its nuclear transfer stage was even needed to circularize the orbit and then do most of the descent burn. But this project, the idea was that the Quad Lander would be totally self-sufficient once in orbit, no Transfer stage. All the launch vehicle needed to do was get it into orbit.

I decided to try a longer version of the two SRB's used for the Space Plane. I set the flight profile so that it would fly straight up, so after burnout and staging it could fall back down and deploy parachutes to land back at KSC, for re-use.



For the "second stage", long tanks added to the bottom of two of the four quads, with small efficient engines on each. Those would do the job if getting nearly all of the horizontal velocity to push the Lander into orbit.


After a lot of testing, it finally worked, though the lander needed to use a bit of its own fuel to make orbit. I second-guessed the use of the big SRB, I had forgotten it was a Nova Punch part, and in this case the performance seemed way too good for a solid rocket booster. That also explains why the Space Plane launch vehicle had so much performance,e due to the use of two of the shorter version of the Nova Punch SRB.

So, I decided to dump that design in favor of a liquid fueled first stage. After more testing I found it needed a bit more thrust and a bit more efficiency. So, I added a couple of smaller fuel tanks to the sides and used turbojet engines instead of rocket engines on them. Those added enough thrust to help get closer to a 2:1 TWR ratio for launch, and did not use as much fuel as a rocket engine of the same thrust level. They did lose a lot of thrust once they got above 15 km, but by then the rocket was lighter and they had already improved the efficiency enough. The rocket burns out at about 30 km, flying vertically, reaching a velocity that is enough for the upper stage to coast above 70 km. The first stage also coasts up to 70 km, before falling back. It has some auxiliary fuel in it to allow the engines to nudge its descent path so it will land closer to KSC.

The "second stage" was similar to the pairs used for the earlier version. But I wanted the second stage pair to be able to get the lander into orbit and have some fuel left over. So I added another tank segment and it had just gotten too unwieldy. Well, it could fly into orbit, but those very tall tanks would fall over too easily. Fall over? More in a minute. So, I went from the 1.25 meter tank diameter to 2.5 meter tanks that were a lot shorter. I gave them legs and remote control capability. Because I decided to make the second stages capable of doing a controlled de-orbit to land back at KSC. So that's why falling over was an issue. Another tweak made was to arrange for the engines of the second stages to ignite at launch, to add another 300 kN of thrust (ten engines producing 30 kN each). Fuel lines from the first stage provide the fuel before staging.

So, if successful, this would mean that the whole rocket would be reusable. The first and second stages only needing more fuel, chutes repacked, and some minor routine refurbishment and maintenance. The Quad Lander, well, if it returned safely, it would also be reusable. Except it would need to have the jettisoned tanks replaced, but that is not a lot to pay for a lander that can fly itself without needing a transfer stage that could never be returned, with the expensive engine(s), electronics, guidance controls, and other non-tank parts lost.

I've never done this kind of thing before, totally reusable 1st and 2nd stages for a launch vehicle putting a real payload into orbit, and a 3rd stage (lander) that only needs to have relatively minor parts replaced. So that's why I decided to do it this time, I had not done that before. Other people have. Tom Beach has done the vertical booster that falls straight back down. and a second stage that goes into orbit then lands back at KSC.

So, the start of the flying.

Shortly after liftoff, burring 21 engines. Nine in the first stage core, two jets on the side pods, and ten engines of the 2nd stage.



After staging, the core coasted vertically to over 70 km. "Computer simulations" indicated the booster could often fall too far from KSC, particularly in a hilly area where it could fall over. So, the design was modified for active control. Seen here, the engines are nudging it so it will fall closer to KSC.



Meanwhile, the second stage pair did their job to accelerate the lander horizontally to nearly orbital velocity. An action group was used so I could turn the 2nd stage engines off as it neared orbit, when a lot of fuel had been consumed and the nuclear engine thrust was enough to provide the last couple of hundred m/s of Delta V. Better for one engine with an ISP of 800 to be using the fuel than letting 10 other engines with less than half the ISP use up fuel when their thrust level was no longer needed (Could have finessed this more so say 6 engines shut down first, leaving 4 burning until their thrust was no longer needed). So, shown below, the Nuclear engine is firing to get int orbit around Kerbin while the 2nd stage engines are shut down, supplying their fuel to the nuclear engine.


After reaching orbit, the second stage pairs were jettisoned. One made a retro burn to come back to KSC, followed an orbit later by the other.




When in the correct orbital phase to make the burn for the Mun, the Lander was fired up. Later, as it neared the Mun, it jettisoned a couple of the upper tanks that were out of fuel.



After getting into a circular orbit at about 10 km, it began a descent burn. Target was the same landing site as the Space Plane landed at.



The 4 crew members check out the flag left by the Space Plane mission, then after spending some time exploring, prepare to leave.



Launching back into orbit, then jettisoning the last pair of upper tanks.



After getting into a 10 km orbit, the crew waited for the lander to get into the proper phase of the orbit to do a prograde burn to leave the Mun's sphere of influence, to get into its own orbit. With Minmus in an orbit that is inclined 6 degrees, the lander needed to do an inclination burn. When the orbital palnes aligned, it did burn to do that, as the Mun, Kerbin, and sun (Kerbol) all happened to be aligned. Then, a burn was made to intercept with Minmus.




In orbit around Minmus at about 7 km, doing a de-orbit burn, then landing on a frozen lake.



Have to split this message into two...........
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After exploring, planting a flag, and taking pictures, the crew prepared to return.




Climbing back into orbit, then leaving Minus. A retro burn dropped the periapsis of the orbit low enough to dip into Kerbin's atmosphere, to do an aerobrake maneuver (small dotted brown oval). It came within about 2,000 km of the Mun on the way back.




The aerobrake maneuver at about 40 km up. It coasted back out of the atmosphere, and was later put into orbit to wait for final descent (for daytime over KSC)



After a retro burn, re-entry coming in towards KSC. Landing a hundred meters or so past the launch pad.





A couple of the crew borrowed an experimental Rover and drove to check out all the parts other launch vehicle that had landed back at KSC Somebody does need to talk to the landing programmer about setting the reentry path a little bit north or south where there are no buildings or big expensive pieces of equipment.





So, the mission was successful. The lander had a lot of fuel left over, more than 1500 Delta-V. It might have been able to land back at the Mun and still return to Kerbin.

There are some additonal images in this album, you have to scroll past the Space Plane images:

Now, I am not using some incredible skill to get the launch vehicle parts and lander to land so close to KSC. I am using the add-on Mod called MechJeb to do things like the landings, and for most of the launches. I did learn how to manually fly into orbit, to the Mun, land on the Mun, and get back from the Mun. And this was way before the game had the Maneuver Node system. Having played the game for a couple of months or so, I had a big rocket that kept going out of control around 8 to 12 km up. I went on the KSP forum for help as for why it was having so much trouble compared to smaller ones I'd tried. Among other things, a few pointed out how the SAS system did not work too well with bigger rockets (it was only really fixed in the last year or so), and someone suggested I try MechJeb. I did, it was finally able to fly successfully, and I was hooked. Below is that big rocket from so long ago, VERY Kerbal (version .16 IIRC).

- George

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Mad props. I would never have even thought of attempting such a mission.