Kesa

For your mun mission, since you don't bother money, there is no point of being fuel efficient, reusable to send fuel into space, or to land on the mun. However, learning to build plane is fun ! What's more plane shows you how little TWR is required to go to orbit horizontally enough : I tend to design good plane and to fly them well, but make over powered rocket, or I don't steer them enough. Designing a plane is way harder than a rocket, but a good plane with little margin is often more forgiving than a rocket on ascent path, and even easier to fly when you learned it (basically because the ascent is much longer, and when you do things wrong, you're just losing energy to drag, compared to have overshot your ap, or worse, to be unable to steer up a heavy rocket)

For remote tech : longer range antenna won't work if there is not a clear sight line between probe and mission control, or between probe and an other ship with antenna and somehow connected to mc. However, it is possible for probe to be told what to do later(see here http://remotetechnologiesgroup.github.io/RemoteTech/guide/comp/). I haven't FAR so I don't know what your ascent profile look like, but with mine, only the circularization burn is out of sight. Just make a circularization node an tell your probe to execute it.

Raising periapse isn't necessary to go to/around the mun. Actually, the differences of energy required is the kinetic energy of ~300m/s (speed of elliptical vs no speed in straight up), which, due to Oberth effect, represents a tiny difference of ~20m/s at 70km. I did not do the math but I expect a not greater difference in theoretical dv requirement to land on the mun. You're damn right about how to test different methods : ships to orbit and ships to straight up are really different. Dv requirement is irrelevant, because high TWR crafts lose less dv, but are often more expansive, and often have less dv. I don't think anyone is going to prove vertical ascent is the cheapest way, but if so, I bet it is not possible without lots of SRBs.

Only a matter of point of view, since we could say this is the kerbin air that acts differently on the craft If that kind of subtle nuancing really does matter, you might want to see : Anyway I only meant that with far installed, launching from kerbin seems as hard as launching from Tylo with a duna atmosphere.

Yellow arrow is trust/mass, red is grvitationnal acceleration (wheight/mass), green is acceleration (sum of the two other) If you are accelerating upward (first picture), your acceleration will be : a = g(TWR - 1) therefore, gravity loss per second is : trust acceleration - real accelleration = g * TWR - g*(TWR - 1) = g which represents 1/TWR of your current dv expend (loss/s divided by trust). You're fighting against gravity. For example, a starter stage with a low TWR of 1.1 will waste 10/11 of its DV fighting gravity, while 2 TWR starter stage will only waste half of dv (but more du to drag, if any), and craft with TWR = 6 will waste 1/6 of their fuel, and so on. If you're accelerating in such a way that your verticale speed is constant (pic 2), using the theorem of pythagore, you have : a = g*sqrt(TWR^2 - 1) Therefore gravity loss per second is : g * (TWR - sqrt(TWR^2 - 1)) < g : Which represents 1 - sqrt(1 - TWR^-2) of your dv : you're less fighting with gravity. For examples, a mid stage booster with TWR = 1.2, it is 45% of dv (you need far lower TWR to achieve same acceleration as verticale ascend). For TWR = 1.4, it is as low as 29% of the dv , if TWR = 2, ~13% of your dv, making it competitive with the 6 TWR monster on verticale ascend. One can also prove that 1/(2*TWR^2) < 1 - sqrt(1 - TWR^-2) < 1/(2*TWR^2) + 1/(8*TWR^4) So loss fraction = 1/(2*TWR^2) is a good approximation. So loss fraction not only is way better for inclined burn, it also decreases much faster as TWR grows, (therefore requiring lower TWR) Finally, when you build up horizontale speed, you are granted a centrifuge force (blue arrow, pic 3). I won't express it with gravitational parm, but as it grows like a square, if we call vh the horizontale velocity and v0 the orbital velocity at current altitude (eg 2300m/s for kerbin), we can write it : g * (vh^2/v0^2) Loss fraction may be calculated as above by replacing the gravity by gravity minus this force, effectively multiplying TWR in above formula by 1/(1-v^2/v0^2), which is 9/8 over kerbin at 800 m/s, 4/3 at 1150m/s, up to infite when reaching orbital velocity (you're no more suffering gravity loss). To sum up gravity loss are by far greater while accelerating vertically. Even with non trust-vectoring engines, you will save huge amount of mass by adding some control surfaces to make an early enough gravity turn. If you like great acclerations, you should ask if a TWR > 2 (arbitrary high but resonable value) worth it : will you really lose less than 13% of DV by adding more boosters? Of course, this is for a heavy body ignoring drag which is reasonable at some altitudes and speeds, and which is always reasonable for kerbin with FAR, since it seems to make drag comparable to stock Duna. If you are going out of a mun with high TWR and low dv requirement, any ascent, may it be verticale, will cost very few dv compared to optimal path. Edit : fixed the image. btw how do you make spoiler?

Well, you seem to be at half the drag of terminal velocity, which is very high, but not dramatically high. With FAR, Kerbin not rescaled, and enough booster, Kerbin seems to act like a small moon with thin atmosphere, validating the "point at your targeted velocity" strategy, which is different than the verticale ascent. Even though, you proved the verticale way isn't the best with a very poor fly path. The difference would be greater if you flyed correctly a well designed rocket. Since I don't use FAR, I won't do any practical fly, but I will try the Mathematical way. For now, what I can say is that gravity loss of verticale ascent is : g*time of burn (~820m/s in your video). Also, your craft is actually using far less dv than usual rockets (it could use even less), that's because of high TWR. But the counterpart is that engines weight more compared to fuel and your rocket has less DV. There could really be a valid tradeoff. Anyway, this tradeoff is not between verticle and horizontal ascent, but between direct High TWR ascent and orbital insertion low TWR ascent

Sorry, steam navigator sucks (it's the first time it makes me that though). Watching it with chrome

Well, your low quality video shows that you use something that displayed information, but I could not figure out which one it was.

I was speaking of Slashy answer, which is clearer than mine, so let's quote it :

TWR of 2 comes from your holy terminal velocity. The definition of terminal velocity (http://en.wikipedia.org/wiki/Terminal_velocity) is the velocity at which drag equals gravity. Basic math show that with TWR = 2 you're sure to stay under terminal velocity (and close to if it's not raising to quick). I can't find where on the wiki it's prove but you seem to agree that terminal velocity is the optimal velocity to make vertical ascent. And with the reentry effect, I highly doubt you are under terminal velocity. You may be misleaded because you use FAR and mech jeb. As stated here in the FAQ : http://forum.kerbalspaceprogram.com/threads/20451-0-25-Ferram-Aerospace-Research-v0-14-4-11-24-14, FAR changes aerodynamic in a way that does not allow mech jeb (and maybe KER) to give relevant terminal velocity.

Nose cone are intended to be heat sinkers for your straped SRBs:cool:

Very helpful and comprehensive, thanks alot!

Nosecones are cool. They have no positve aerodynamic effect, because their two purposes are to make cool looking and to cool your straped SRBs.

Watched it. It's actual crap:confused:. You only proved that a poorly designed craft is inefficient no matter the way you choose.

From what I understood, your concrete mathematical numbers just say that without any gravity loss (or with infinite TWR), vertical ascent to an intercept to the mun saves ~20m/s, which is nothing. But even with high TWR, I bet that vertical ascent is worse than throttling down to TWR = 2 until out of soup and then full throttle with a more brutal turn. However, I can't figure out how worse it is, so it may be not that worse, depending on TWR, escape velocity you want, SOI size... For small body, TWR is often very high and escape velocity is low, so as someone mentioned before, the best is to accelerate toward the escape velocity you desire, may it be vertical (and vertical is the worse case). But as for canyons, I don't know at all how to manage them. Maybe full throttle until your apo allow you to burn toward escape velocity. And in that case, vertical escape, when possible, might be the most effective way out, especially for the Mun which has a rather high escape velocity (but since it's tidally lock, you'd better chose your canyon before landing:sticktongue:) edit : your numbers I'm speaking are those from the previous thread, I did not watch the vid, poor connection

Just a note to say that if you really want to compare the two methods of ascent, you need two different types of craft. Saying "my 4 TWR ratio rocket failed to make orbit" as well as saying "kerbal X fail to make vertical ascent" aren't valid arguments.

Picking it from the wiki, the max temp for the mainsail is 3600, so DRE does affect its max temp (making it 1800, and starting to burn a bit before) http://wiki.kerbalspaceprogram.com/wiki/Parts#Liquid_Fuel_Engines

Engines overheat on their own. The first think I can think of : deadly reentry. It greatly lower the heat limit of every parts (divide by 2 most of the temperature tolerance). Here are my advice : (1) As long as the mainsail does not explode, don't bother overheating. If it does : (2) keep other engines away from it (if they are not just beside it, it sould be fine) (3) attached parts acts as heat sinker (aka radiator). If you have any mods that add radiators, they probably are intended to be on your craft, between the tank and the engine. if not, you can try attach radial thing to the engine/tank. Also I don't know much about how ksp manages heat, maybe some structural parts are better sinkers than tanks (and I don't know at all about KW tanks, you sould maybe check stock tanks) (4) throttle down to a safe point, and throttle up when your rocket goes higher and the engines less overheats. (you might add srb to compensate the losss of twr at launch) edit : ninja'd

Actually, I once made a big plane looking craft that had anything to make mid game science (including processing lab) that rolled on Minmus from biome to biomes on C7 gear bay and propelled by LVN. It safely could go up to 50m/s. Oh, and quicksaving/loading was great.

I'm glad you made a new thread with new argument in favor of vertical ascent, which I might have underestimated .

I'm doing biome hoppers for Mun and Minmus and I wanted to know (but am to lazy to do the math) : at which angle should I throttle to travel a given distance the most efficiently? (1) If you assume the planet is flat with constant gravity, you will go further by accelerating at 45°. (2) If you go for orbit, you want to burn horizontally as soon as possible (0°) (3) If you want to go to an other biome, I expect there is an optimal angle between 0° and 45°, depending on how far you want to travel. Some reasonable assumptions : - instant burn, since we're on low gravity - moon is perfectly spheric - gravity might be constant (but I'm not sure it helps, since I expect someone using ellipse)

Is there any reason apart from style/rp to have bigger (and heavier and often consuming more) probe core? May it be stock differences or mod introduced.

I'm pretty sure the lost due to gravity is something like 1/TWR of total DV for vertical ascent. I was thinking it was the difference between the two methods, but I forgot that going to LKO also generate gravity loss. With an autopilot and a typical rocket (starting with TWR=2), I think you lose between 1300 and 1400 m/s to go to LKO, wich is roughly 1/4 of the bare minimum of 5600 to go to an intercept with the mun. So I think that with a TWR > 4 (it is lower than I expected), it might worth go vertical. Also note that by going to orbit, you only endure grav lost during the ascent to LKO, while going vertical, you have grav loss all the way, so Interplanetary vertical ascend require even greater TWR to be competitive. Also, I don't know how many dv you lose due to drag during ascend, and if there is significant differences between vertical ascent and going to LKO. As I see in your math, supposing instant burns, there is no significant differences between DV required to have an intercept or a mun-like orbit. The main difference will be in gravity loss. I like to think that going to orbit (or even better directly to intercept like wanderfound described) is always more efficient : with high TWR rocket, you would have gravity loss lower than 1/TWR, even lower than 1/4, but the differences tends to disapear, up to be negligible regarding the unavoidable loss in the souposphere. As for cost, the only way to have high twr at cheap cost is SRB. But you can also use srb for an orbital insertion. I have a probe under 5.000 kerbucks that uses 1 RT10 and I think I have a 1 kerbal lander that might cost under 30.000 (using srb also). Further more, getting the max out of srb is harder that using LF engines with customizable amount of fuel.

I disagre, when accelerating vertically, you go higher very much faster than horizontally on LKO, losing speed (and gaining altitude) actually reducing the oberth effect, especially for burns that typically takes 1 minute or more. So Lko makes a better use of the oberth effect. What's more, I guess if TWR = 3, vertical ascent will waste 1/3 of Dv. Nevertheless, you need at least TWR>1, and the higher is the better. Vertical ascent needs heavy/inefficient engines in order to achieve high twr, counterbalancing cost and size required to have steering system on a vessel that can go from lko. You can go from lko to transfer orbit with Twr =0.5 or lower, with lighter or more efficient engines. Eyeballing is easy when you know how (and when) to do it. As I stated, the only advantage of vertical ascent is that you don't have to know how to go in LKO. What I forgot to mention is that going to LKO might be difficult the first times (and I trust you this is even worse with FAR. Consider though that winglets are light and that the rocket get less wobbly when on upper altitude).

I don't know what the op meant by "directly to the Mun", but at least for those who assume it's a Vertical ascent vs LKO debate, here is my answer (btw it took me a long time to figure it out) : LKO : Basically, all the energy you have from your horizontal velocity at periapsis is converted into potential energy when you are at apoapsis (and very little amount of kinetic energy for your velocity at apoapsis, which should be less than 300m/s, so less than 1/100 of your initial kinetic energy. Speaking about Dv, it means you have to be 15m/s faster at periapsis than for a vertical ascent). That why you do not lose any dv/energy by circularizing first. Vertical ascent : At first glance, there are several advantages : - your trajectory is easier. - you go out of the atmo faster, therefore having less drag. - you don't watse time/fuel to achieve an orbit - It's quicker. But they aren't that advantageous : - since you have to eyeball the good timing to launch your rocket, trajectory might actually be harder than setting mmaneuver node. Since Mods/calculator of launch window assume you come from LKO (guees why), you can't use them. (you can still use them for interplanetary travel). - to achieve LKO, you begin to turn when the atmo get thinner, so the difference is not that big. - as stated before you don't lose anything achieving lko. - Further more, gravity sucks by far more energy than drag. Imagine you got TWR = 2. by accelerating upward, you will have an acceleration of 10 m/s. But if you turn your rocket in order to stay at the same vertical speed, you are accelerating effectively at 17m/s (10*sqrt(3), even more when approaching orbital velocity). Even with TWR = 10 (~half the weight of your rocket is engines, and you hit the red bar of g force), I bet you'd waste 1/10th of your fuel. - It's not actually quicker. First, you need to wait up to ~one day (7h12 hours precisely) for the good time to launch, while LKO period is up to 30 min. Then, you also can accelerate more than needed from LKO to be quicker to the mun. Finally, the only advantage of a vertical ascent is that it does not need you to know how to orbit.