PB666

Everyone remembers the https://www.xkcd.com/1244/ But just what can you do in Kerbal space program? So I have a ship in LKO with 30,200 dV of fuel, and I could pitch out 1500 dV leaving 28700 fuel and burn at the angle to prograde around 180 and then arriving in front of kerbin burn on the 10000 m/s cricumkerbol velocity for a total of 38700 plus whatever I had when I left kerbin. Jeb however left me with one astronaut, bob, needs or two planets and a deep space mission. I could plan my mission to fly by duna on the way out, and try to get a fly-by of Ike, but Jeb claims that there are secret resources on Moho. As everyone know Moho is a dV hog. So lets do some Oberth. First I head to Duna, approach is from kerbol side Remaining dV is 27400, As I pass Duna I use a reversal of the oberth affect around Duna to slow me down relative to Kerbol This also gives me a chance to change the course so that I get a close flyby of Ike, Ike has no atmosphere to speak, I can get very close and use the oberth effect to create an ellipse that crosses but does not intercept moho's orbit. By this time the ship is on the space side of Duna just beyond the pe, heading to Ike. Two close flybys done, now for the third, its a ball-buster. Once I get to Ike once again I use the oberth effect to create an intercept course with moho - dV is now 25900. Unfortunately the plane change points are close to latus rectum points, so I can't burn normal/antinormal for the 7' I need I then make my plane changes and im down to about 24900 dV I am not lucky enough to intercept Moho at periapsis, but once I reach the Kerbol periapsis, I can add just a few prograde dV (which I will get back a later as we will see) to create an orbit that intercepts Moho. Moho does not have an atmosphere and turns relatively slowly, so you can get close enough to fry dust bunnies. At Moho intercept about 5.5 GM im traveling at 18 km/sec versus Mohos 13.5, dV remaining is 24,812. After entering Moho's SOI I burn just about as much fuel as I can and by the time I exit my circumsolar velocity is now 26,900 m/s and I still have >15,000 dV left Since I am basically traveling perpindicular to Kerbol I can burn out the rest of my fuel, the final velocity is 42400. Now you might think aha but by the time you get back to kerbin orbit you will have lost alot of velocity. Actually because I accelerated so much in the moho flyby, getting back to Kerbin only robs me of 1800 dV so that by the time I reach Kerbol Im going 40000 meter/sec and by the time I leave the system (200GM) im going 39,500 m/s. Logic should have it that if I did a retrograde burn at Duna, an inclination burn near Kerbin orbit that I should not have lost much of the dV for my fast exit, but because I save dV on two retro oberth effects, and saved dV on one positive at Moho, and then burn heavily at the at the low point of my circumkerbol orbit, I manage to obtain very high kinetic energy, only a small part I needed to give to thermodynamics, the rest was kept of my kerbol system exit. This is another peculiarity of the oberth effect, depending how much you burn just before, at and just after you can use the effect to adjust course to flyby objects, and in the end you can get energy back to do high velocity things like leave the system or search for kuiper belt objects, whatever.

Right, and in a perfect world that exhaust velocity relative to the ship is exactly equal to your forward velocity. But more to the point, that exhaust is now stuck in a gravity well.

Before 1.0 I used to make Jet powered launch platforms, once I got up to about 300 m/s and 15 k I would launch my rocket. This was particularly useful for launching telescopes and other objects with large profiles. Since a turbofan is just a propeller based craft that compresses air to create thrust they tend not to work well as the air thins. But the thing is that they can lift at any speed, so that if you have something really delicate, it gets you out of the messy atmosphere. Unfortunately in the game I can't land both the launch pad and the rocket. 10 or 15 of PW4098 put the platform about 30 meters off the ground, at 100000 lbs of thrust per unit you could lift Just about any payload you want. The only limitation is that you need to keep it vertical and it would help to feed it oxygen as the air thins out. The reality on Earth is that the P&W4098 generates that level of thrust for takeoff, which means you need some air motion and thick air, and in addition cold air works best (it expands the most when heated). It has an effective ceiling of about 50,000 feet or 16km, but that is at full velocity, 50k feet is its coffin corner with no load, unless you are moving forward that stall height would be much lower, around 10-12,000 meters, and the maximum thrust at the output is a quarter or less in that range. You could engineer into the platform an air induction that feeds the turbofans air, but this adds mega-weight. The basic reality is for jet power first stage on earth is that I can entirely replace it by putting my launch site on the side of a decently high mountain in Ecuador, and add a few boosters. Even if you landed the platform, the cost of fuel and structure in the boosters would be less. For one, you need RCS thrusters on the platform to keep it level. For most jet engines, despite the fact that they can generate an awful lot of thrust, the point in a flight were jet engines are most inefficient is when they trottle up to take off. This is because on the ground air is hotter (further away from 0K), and the compressor is really designed for sustained speed at around 500 kts at high altitude. For space craft that need a delicate launch. Launch from a high elevation, have a series of small boosters that are shed on the way up, control velocity with the main engine, launch entirely vertical and maintain, when the altitude is such that crossing the Mach barrier produces little hammer force on your flat forward facing surface throttle to full power and begin gravity turn.

That was a few years ago, the problem now is that close objects with short periods are more easily detected in transects, if an object has a period of a year, like earth or 1.5 years like Mars, AND you need to see at least 2 periods to propose and 4 periods to confirm then you potententially have to observe the star for 10 years. That is a problem because the Kepler observatory is a bit crippled (not just a bit, very crippled). We can see small things transcent but we stumble seeing small slow objects transect. I think it is mute in some regard, smalls stars are long lived but tend to be flare stars, none-the-less have the largest potency to support intelligent life, those stars would have planets in closer orbits with shorter periods. Stars larger than the sun will have shorter lives, with habitable zones further out, and slower periods, but less likely to survive long enough to have intelligent life.

But it could catch titan specifically orbit around saturn on the sun side, how fast dies titan orbit saturn? Poor pluto, doesn't even get pock chopped anymore.

How about Solid sphere with dust on surface that orbits Wet surfaced sphere. That would be much easier.

I'm still trying to figure out how the romans figured out how to make bleach blonds.

If you survive long enough and you have a dedicated space faring culture, then it is possible to wait a few 100,000 years until another star passes close to the sun, at which point you could travel 1 ly or so and the expand a space fairing culture. If you kept doing this at the rate of say 3 per million years you could move away from our position hitchiking stars at aroud 3000 m/s giving an idea how fast you could expabd, each expansion, by definition would create a new species. I think our interstellar future should give up on this fixation with habitable, what you really want is resource available systems.

Thats very original, where have i heard it before.

The intercostal canal with heavy loads weaves through Port Isabel and butts into the Brownsville ship channel. According to their design layout it does not even come close to the launch site, everything you see is dependent boca-chica hiway which right now is a relatively low grade two-lane road. Provided that the significantly upgrade the road, they could create a facility on the south side of the of the ship channel. Im not concerned about the Rigs, that would be fredinno, he's fretting over rigs and Mexican stargazers. I know the rig count is down, they are few and far between in the south texas offshore area. I have run the length of the intercoastal canal from just south of Mansville down to the BSC, my favorite spots in the 70s were markers 99, 100, 101. And we also used to fish the spoil islands up near the Arroya Colorado cut-off, more recently I have fished the region in front of South Bay and at the intersection of the IC canal and Brownsville ship. South Bay is not navigable by commercial craft, its barely navigable on a spring high tide with low draft craft. This is the bay that butts up against the Space X control facility, salt marsh that butts to the launch pad is an overflow zone for the Rio Grande, it is not accessible from any of the Navigable waterways to the north. As I said in the other thread, you could extend a channel around the west edge of South bay and connect with their space facility provided you got permission from federal and state government. Not against that at all, would improve the fishing.

Put the drop tank on the SRB and time it to empty when the SRB is finished, then drop it with SRB, since lf and Ox have to be separate place planes or fins into the tank that flare when the tank is released cause it to slow down more rapidly. then use a small amount of thrust to land it. Its recovered, problem of recovering SRB is solved, you have a little lf-0X on top to power a controlled landing.

Yes, but its not a matter of what our system is, the average detected system has gas giants inside the habitable zone. Our system is highly unusual, that we know of because it has relatively small rocky planets inside the habitable zone. I can buy 400,000 in our galaxy that have some point in their existence life, most of those worlds orbited stars that died or blew up or snuff out because an adjacent star blew up. The fact that the universe is very big isn't material, or that our galaxy is very big, is also immaterial. Space travel is not easy, and pretty much half of the habitable galaxy is too far away to view. Even more so, if you go out to Pluto's orbit and point a big telescope at earth how much will you here, alot, alittle, mostly alot of cell phone static. So lets all scale this down to the next variable, how much life exist in places that we might actually care about, let's say, in the next million years (assuming that going across the galaxy at 0.10 the speed of light would be a fantastically great achievement) We can basically draw a circle 10,000 ly (you cannot travel constantly you have to land, rebuild and then venture out) around our sun and describe that as the we might care zone. Ok the galaxy is 300,000 ly across its 900 times that size, and you reduce that 400,000 down now to 500 systems have life and intelligent life maybe 1, 0.1, 0.01 etc. Then we can look at it from the point of view of intelligent life lucky enough to moved to another star maybe 1/100, 1/1000, 1/10000. Or we can ask the question in a circle of say 7500 ly, how many starts are close enough and produce a big enough signature that we might observe that signature from earth. Here's another metric. Life has been on this earth for 3.8 billion years, however in 500 million years or less, all life including intelligent life is likely to be gone. So in the 4.2 billion year timeframe, At most intelligent life only exists for 11% of that time max, and that is only on one of three planets inside of the habitable zone, therefore even in deluxe habitable stars the odds of actually seeing intelligent life is not good. If we are more practical, it not likely that life sentient life will exist on this earth for a fraction of that time, we either become space fairing soon, or its like the sentients will die out, which a resource issue for the next sentient to come along. In fact if we take the current measure for 200,000 of the last 3.8 billion years has life sufficiently progressed that we could carry on a conversation if the materials for conversing were provided for us, and less than 150 years since the famous EM experiment demonstrating that electomagneti pulses can be communicated. So our range for sentient proportion is from about 150 to 500,000,000 of 4.3 billion proper. Its not good statistics for concluding that sentient life can be found. Earth has had life on it for 3.3 billion years, but only sentient life for 200,000 that metric is 6 x 10-6. But if you peg - this planet might be habitable, which means if falls in the goldilocks zone, and then 1/6 bodies of our habitable zone have life and the one that has life has sentient life for only 1/160,000 of its total quantifyable existence, the 500 habitables in the We care zone is not impressive. I am waiting for someone to prove me wrong, but if I am an alien life form that just happened to notice a blue planet with a O2/N2 atomsphere were they expect C02/N2/Methane I would probably ignore further investigation of that planet until more signal information was available. I might even have a odds going in the Alien Vegas if the sentient life existed and about how long that sentient life might exist, and send a meager coke can probe out to signal when life went phzzzt.

China it is understandable since it has nuclear weapons. I would find it hard to believe that RSA political governces cares about what mongolia believes.

Theoretically you could use rf before the object ejects and lasers afterwards to creat a vacuum hole in the atmosphere, the point however is the ship is limited to1600 m/s. So whats the point of doing it. Just by launch at 5000 meters affords a reduction in drag and demunition of the thermodynamic energy required tonreach orbit.

The only problem with that big foil plate ousing a coke can that weighs as much as a paper clip and sees all knows all and transmits all back to earth.........The laser energy he proposes on occassion would destroy the big foil plate. Second tracking, you arrays are gathering juice from near sun orbit,mthey are in orbit about the sun, how do they track a plate so small that even hubble could not see it.

I don't even think simple life is common, it think you have two planets in our systen with a fortuitois star and arrangement of planets that may have tolerated lifes start twice. There are three planets in our habitable zone, two are currently dead. That basically goes to showvthat once life starts there is more than eve chance that it will promptly die. I'de like someone to prove me wrong, all ibsee is exoplanet jubilee with each new duscovered followed by, well, no its really just a hot barren planet orbiting and unstable star that probaly does not have an atmosphere and we think it was blown away a few seconds after the star went bright.

Is this a stated policy of Russia or are you imagining that it is, Soyuz goes to ISS which is in an inclined orbit.

That well disciplined science of naming stuff that has been named 1000s of years ago and that everyone will ignore once you name it. Let me ask you a question do you call a dog a dog or canis lupus domesticus. Even if you speak a romance language you still use perra, perro, cane, mashio

Like the shuttle brick-gliding in for a landing?

New horizons does not have enough forward momentum to cross the galaxy, it would pretty much stay in a orbit relatively close to the sun for 100s of millions of years. If you consider it takes 250,000,000 years for the sun to make a rotation and its current position is 27.200 klight years from the center, that is 2.7x10^20 meters. The angular velocity is 8.42883E-17 radians per second and at this radius an object that has escaped the Suns orbit would have to accelerate on the direction of the New Outer arm of 22,000 m/s to fall into and out of the center of the galaxy. The new horizons will stand to loose another 1000 m/s before leaving our solar system with a residual velocity around 13,000 m/s, but horizons is heading in the direction of the galactic center, which is -radial, which means it has created a eccentric orbit that will travel toward the center, stop and then travel outward with basically the same period as the sun, which means it will oscillate around the sun as it travels around the galaxy (galactic physics aside).

Great, but do we need another ISS? Were are going to toss the current one in a decade. Alot of the weight of the ISS is not dedicated to habitation space, each of those solar arrays weighs 14 tons. So its not a 1/5 reduction in weight, the launch profile is a definite improvement. But we must remember that each ISS module goes up with most of the equipment installed. If you send up a compacted module, you won't also have space for the equipment, so you will have to bring up that equipment later and install it.

Same thing, magnetic particles have mass, very low mass btw which means they have alot of drag. So you still have to have a very high structure. And BTW, ozone in the atmosphere is quite polar, it will accelerate in a magnetic feild. https://en.wikipedia.org/wiki/File:Ozone_molecule.svg ONce the ozone reaches the upper layers of the atmosphere it will react with hydrogen, nice fireworks but that completely destroyes the stream and the ozone, which would have the environmentalist at your doorstep. Oh, and you have another problem.. . . . . https://en.wikipedia.org/wiki/Ozone#Production....There is no such thing as a purely magnetic particles, throwing a stream of magnetic particles in motion would create electromagnetism and there would be an electrical component. Serious engineers, I think not, may as a hobby. Carbon nanotubes are not hype, they have their place in nanomedicine and similar applications. Don't forget the laws of energy conservation, if you have a payload of a ton you need something that produces 10,000 newtons of force (1 ton of weight) to keep it up against gravity. If you are going to accelerate against gravity you need 20000 newtons of force applied against a 2-D object, how big is that plate going to be a football field, 10 football fields, 100 football fields.

I wish ISRO well on the effort, sounds interesting but.. If the preferential launch site is southern india then, hmmmmm, looking east to territories https://en.wikipedia.org/wiki/Nicobar_Islands#/media/File:Nicobar_Islands.jpg There are alot of protected areas in these islands.

I forgot to add - 5. By increasing altitude more quickly during the early flight phase it maintains fuel while diminishing drag. Yeas, not RL. But since I make my own parts I can deal with some of the differences (like for instance having an SSME with 453 ISP). But the points are still valid, its a major reason that all the space programs use a launch stage or boosters. The differences between KSP and RL 1. The orbit is 7900 m/s versus 2300 m/s 2. The surface moves 400 m/s versus 175 m/s 3. Earths R = 6371000 versus 600000. This means that for Earth the thermodynamic potential for reaching space at the same altitude is slightly higher (about 11%). 4. Earths atmosphere is thicker at the lower levels and drops out less quickly. Mount Everest is about 30,000 feet (9840 meters) but the atmosphere is a 1/3rd. Kerbin atmosphere drops 1/2.6 by 5000 meters, by 10000 meters it is around 1/6.5 (about half as then as Earth at the same altitude) The result of the difference 1. The need for dV is greater, since the ISPs are about the same, this translate into the need for more stages on Earth. 2. The surface movement slightly reduces the dV thirst of Earth launch. 3. KSP based rockets start experiencing significant reduction of gravity the moment they take off, for an earth based rocket to experience the same difference it would need to travel 10.5 times as far away from the surface. 4. Earth based rockets have to be more streamlined and turn to horizontal less slowly than in the game. The result in terms of staging. A. If a rocket designed on Earth has just enough thrust to hold velocity at maximum dynamic pressure on earth meaning it rough has 2g of acceleration and with coefficient of drag it can accelerate to 0.90 Mach at 1 ATM (which mean that drag = force of gravity at that speed) then its surface relative acceleration will follow a path of roughly 1G to 0G with average acceleration of 0.75G. At the same time it would be burning fuel, to maintain that acceleration from launch it would need additional thrust or it would be wasting fuel. If a booster provides that thrust and then falls away at maximum dynamic pressure, that booster is providing the most possible benefit to the rocket Reason - the time that a rocket spends over the launch pad trying to gain maximum allowable speed is the time that consumes the most fuel per distance traveled in flight. Math - Energy (work) = Force * distance traveled The less distance traveled while applying a force, the less energy that is created. Energy(work)/Mass = Acceleration * distance. = Thrust/Mass * distance Since an ideal rocket engine (that means not over powered and thus weight wasteful) reaches around 275 m/s at which point it no longer needs to accelerate until it loses drag force and fuel, and since it takes about 40 seconds to reach this point and since a typical rocket has about 5 to 10 minutes of fuel at full throttle, that rocket at 40 seconds would have had more weight than it needed to push at optimal altitude, its ISP would have been 5% lower. IOW it would have had around 20 to 30% more weight than its engine could efficiently push at lift-off. Theoretically it needs a booster(2) that can lift that 20 to 30% more weight and itself at 2g of force. Since you need 2 for balance that equates to 10 to 15% of the weight plus its own weight, and it roughly needs to burn for 40 seconds. So if we just want to take care of 1 set launch specific inefficiencies, the lack of optimal momentum and ISP at launch, we need to use boosters or a different first stage. Kerbal or not, the problem is the same. The next problem is the circularization phase. Lets state the problem. Suppose I want to place something in high earth orbit or in orbit around the moon. Once I have a circularized orbit, I don't need much of an engine at all, I can kick my orbit at pe several times to get altitude, so why would I carry a launch engine that gives my craft 100 m/s of acceleration once it has burn most of its fuel. Second question is why would I carry all those fuel tanks. Having dealt with the atmosphere and launch inefficiencies its time to think about circularization. There are two basic problems, simplified to the ridiculous, heat and drag going horizontal and lack of horizontal motion going vertical. The primary issue is how much engine do you need to circularize, the answer is that in order to gain horizontal you have to have enough thrust to counteract a significant portion of gravity experienced. For example the sin of 30 degrees is 1/2, so if the engine generates 2 g of thrust it has enough g force to counteract gravity at 30' once drag has been reduced to the point that it does not cannibalize important momentum and 0.86 of its thrust can go into horizontal acceleration. Since it needs to be roughly 7900 m/s - 400 m/s or 7500 m/s and it can get 2 * 0.86 * 9.8 = 16.85 it needs to burn about 444 seconds at this force to reach its target. Note: it is important to state that vertical acceleration is important for two reasons - first to add thermodynamic energy to the orbit (which the craft keeps and uses) and second to waste, as little as possible, in fighting the war against gravity (u/(alt+surface radius) - omega^2*(alt+surface radius). To waste as little as possible we have to gain horizontal velocity rapidly and altitude less rapidly, the reason why circularization quickly is better than burning up. However, as it burns the fuel its mass decreases and its engines become overpowering, but the problem is more profound according to omega^2*r once it reached Vo of 5925 it only needs 1/4 of its thrust to gain to maintain verticle speed irregardless of weight loss. This is about 333 seconds after maximum dynamic pressure for the engine which has already 40 seconds, which means the engine has been burning for a total of 373 seconds. Its ISP is 435 seconds in a vacuum, its time to shed that engine and tanks and go for a combo that produces 1/10th the thrust, with an engine weight of 1/20th and is efficient. Instead of an engine that can carry something at 5x*2g you need something that carries at 1x*g. Heres the point. Once gravity is sufficiently tamed ______ that is when (u/(alt+surface radius) - omega^2*(alt+surface radius) is much closer to zero than surface gravity , its time to get shed the antigravity gladiator and invest in a dV miser. Since the craft still has vertical momentum it can consume that momentum with a lower thrust engine and burn to horizontal. One other very important point also, that huge engine and stage tanks are traveling at 6000 m/s, it falls back to earth with no need for a decay burn. So there are three good reasons to have a second stage even if one has two boosters for the first stage.

I have a better question, why exactly is the thread in this subforum? doesn't it belong in general discussion.