Reusables

You mean kinetic energy element from downward part of the velocity? Sorry, but this is really confusing.. Wouldn't it be better compensated when actually moving downward? Also I think potential energy, horizontal kinetic energy and vertical kinetic energy will exchange some energy with each other, which confuse me even more. Would you provide more explanation on this? So it's not actual graph.. I was looking forward to one

Would you clarify this part? Specifically, what's the 'unwanted kinetic energy'? Do you mean the excess energy converted from the potential energy(as gravity turn needs losing altitude)? Also, is it local optimum? I'm looking forward to seeing the graph, please let me know where is it or how to find it... So it's much more complex than Oberth effect if I understand it right. I don't get what you mean by 'periapsis'. With its original meaning, shouldn't it be underground?

Sorry, but I can't get this part. Won't you get cosine loss from misalignment of thrust and velocity, resulting in less energy loss? Moreover, as gravity turn let vertical velocity build up, it will have more speed overall resulting in more energy loss. What part of this is wrong? Also, I can't find the dv of gravity turn landing from the article you referred to. Would you tell me where I can get it?

What I wanted to say..

Any moving parts won't propagate its movement to it's child part. So no more control authority. Though, you can surface-attach something(including elevons) to Big-S elevons and FAT-445 elevon. It is just for aesthetics, I think.

In my recent career save, I tries to recover everything w/o disposable parts - separators, fairing, and heatshield. To achieve this, I usually design fully recoverable launch vehicles. e.g. I'm curious about how many of you plays like this - Have you played like this once? Is your playstyle involved with reusablity? Or would you rather dispose of anything you don't need?

Satellite on specific orbit contract is usually generous in my experience. You could have 1 degree of inclination and still complete equatorial orbit contract. So you don't have to try to do it precisely. Besides, I think what you mean by 'eccentric orbit' was circular orbit. It's an orbit with circular trajectory, and the Ap and Pe has the same altitude. It's really hard to get into one, even with 10m of margin on LKO! Though as mentioned above, contracts are generous enough to allow over 1~10km of margin(for keostationary). Just make an orbit similar to the contract orbit with burns on Pe/Ap, and it will be marked as complete.

If you connect the payload stage with docking port jr., you can enable staging on the part. For this enable 'Advanced Tweakables' option on the Esc menu if it's disabled. Or you can simply decouple it instead of undock. (on the right click menu) Since you are using fairings as shroud, you may as well disable the engine shroud. It's one of tweakables of engines.

The same happens with Earth; 365 days after periapsis, it doesn't reach periapsis agaon. Leap year makes up the difference. This could apply on calendar of Kerbin as well.

Odd, the wiki says it and I think sunrise time is still dependent in the day of the year. Anyway, just realized that this is unrelated; (1year in sidereal day is exactly 1 bigger than that in solar day) 426 day should be some kind of compromise for simpler clock. There could be leap year.

The wiki page covers this pretty well. Kerbal day is Sidereal Day, so 1 Sidereal Day = 6 hours / 1 Solar Day = 6 hours 50.8 seconds / 1 Year = 426.08 Sidereal Day on Kerbin. By the way, it's pointless to differentiate Sidereal/ year in Kerbal universe. It comes from axial precession, which I believe is not implemented in KSP.

So I experimented with Panther and Engine Nacelle. And.. This lifter had no problem like asymmetric thrust, and lifts 2t in 656 So 328/t. Impressive! EDIT: Tried Whiplash. At the first time I thought it won't worth it because I just didn't put enough payload on it. Now I realized it just needed more payload. 272.76/t. I don't take the screenshots of takeoff and such, so this won't count as entry as well.

Thanks. The separation altitude is about 16km~18km. Usually I only mount OKTO probe on the first stage, so the SAS torque force is next to nothing. Though I need to turn off SAS sometimes, because electricity runs out otherwise. That's what I do as well. I usually set the altitude to 250m~500m depend on lifters. Also I set the spread angle to 10 for every lifters. I was looking for low-tech lifter, thus the Panther. I thought whiplash is not good for the first stage booster since it works better on higher altitude. It gives nice push on supersonic region, but it's 50% heavier and a bit more expensive. Now realized that it could be better option, I should investigate it. Besides, now I realized that Divertless Supersonic Intake was probably not the best choice. Engine Precooler is too expensive, but cheap Engine Nacelle might provide enough air as you demonstrated with a test. I was using the cheap Divertless Supersonic Intake. It lacks intake air on takeoff, so I need two mk0 intakes to prevent asymmetric thrust. (I think the bug retains when intake air is not enough just after takeoff) I think boostback is really hard to perform with airbreathers, since you are already high up (typically over 30km) when it's needed. Then, more horizontal speed means more distance from KSC(less recovery rate). Anyway, thanks for kind feedback and advice! Yes, this belongs to the category II (Reusable Lifter) as @WanderingKid said. That's it! Orbiters tend to be more efficient with heavier payload. That's why I don't bother to list light entries even if it's less efficient than those heavier ones.

Found a use of Panther. It's useful for rockets as well! This small 'rocket' which lifts 2t to LKO only costs 344.5/t! Also there is room for improvements; I think I already shaved off 22/t, so it will be 322.5/t. Flies just like other TSTO launch vehicles, with a bit different speed profile. I regret that I hadn't unlocked the Panther... EDIT: Here's a refined version. This gave 328/t.

@OHara, indeed! I forgot that there were airbreathing engines. As they have great fuel economy, they actually fit well in reusable lifter as the first stage engine! For instance, I got 344.5/t from this lifter: (Didn't take screenshots of its flight, so this doesn't count as entry) I got the second stage from my previous lifter. 400kg of liquid fuel was enough for the first stage! The problem is engine cost; The two engine consists 88/t of loss. (I got recovery rate of 95.6%) Still, there are rooms of improvements; 75/t comes from other facilities aside from air intakes. Better design will reduce the cost. Also if there's a way to handle the asymmetric flameout just after launch, I can get rid of the two small intakes.

As far as I know, the KSC monolith is an anomaly only with visual effect. (I don't recall if it had collision mesh or not) I heard that discovering green monoliths grants some science points. Those will be only ones with actual impact on gameplay.

I'm a theoretical scientist. I like to assume ideal conditions for calculation, while don't like performing actual experiments. These calculations are used to select the best ones and optimize crafts. Also I usually calculate minimal requirement for certain mission, and add some safety margin to make a craft. These calculations usually take time, so I sometimes 'guesstimate' things with rough numbers. It's not blind guess, though, as this is calculation with less digits. For instance, I took the process while designing my reusable TSTO lifters. 1. I checked the validity of it via calculation. I concluded that boostback doesn't worth it, as it typically needs 300m/s more dv and recovery gain was relatively marginal. 2. Built a prototype to verify that this works. Used the best engines in the case, with the help of calculation above. 3. Flew the prototype, and add/subtract bits till it works efficiently enough. It's not as good as theoretical optimum, but reasonably good as practical ones. Besides, I may have some aspect of pilot. When I get bored with playing with the numbers, I get up with some absurd idea and put things together to make a contraption for that. Like fairing plane which is capable of belly landing. It's kerballed missile as well

You'll probably need KerbNet Access for that. Open it, target KSC, and activate navigation. Alternatively, you can plant a flag near the runway. Simply target the flag.

Thanks! I got my reusable lifter working with higher TWR. I can't get LKO with 3.2km/s, but there was certain improvement: According to scoring in this challenge, this costs 290.94/t with 140.1t payload.

Completed the 140t lifter. Had to add some fuel on the first stage for the wings and safety margin. 140.1t to LKO under 300/t, Payload fraction 21.65% EDIT: Craft file - flight instruction is both in the craft description and the album.

These comes to my mind. I. Simple & Economic (Unhealthy) 1. Wait for Duna -> Kerbin transfer window. 2. Get Val out of the cozy cabin. 3. (Optional) If the plane has a probe core, point one of the nuke engines to the Val and turn it on. Val should gain reasonable speed with it. 4. Use jetpack to plot a nice Ike gravity assist to escape Duna and intersect Kerbin. (Ike flyby costs about 400m/s, so doable) 5. Let Val wait for countless time during the transfer. 6. Rendezvous and catch Val with rescue ship. II. Fast (ingame time) 1. Design a seat with Ant engine, which will grant you lots of dv in a small package. (~3km/s) 2. Attach Spark engine stage to the seat, which will give you extra 3km/s of dv or so. 3. Design asparagus-staged nuke interplanetary ship to haul the seat above. 4. Lift the above spaceship to LKO. 5. Shoot Duna with it. Literally. (*Effective when Duna is close / If you unlocked an ion engine, use it instead of Ant/Spark) III. Reusable 1. Launch a Reusable SSTO with klaw. The same spaceplane with a klaw attached would work. 2. Reach Duna orbit. 3. Rendezvous and grab Val's plane. 3. Tug the spaceplane back to Kerbin. With proper aerobreaking, I think dv needed is about 2.6km/s on LKO. (Considering the increased mass after grabbing) Though, these are just suggestions. Do what you want

Right! Gosh, I should be bad at communication. I'm sorry. (Besides, I was confused because you mentioned numbers; A number can be either scalar or 1-dimension vector)

Started playing with airships, ended up with amphibious seaplane which can land on belly. Fairing is really OP, it has basically infinite impact tolerance. Structural failure is the only possible cause of explosions given that all parts are shaded in the fairing.

This is contradiction. What do you mean? Multiply u and v? Why?

That's scalar... scalar does not contain direction while vector does. Yes it is. Also, if it works on some system, it works on every system since reflection/rotation/translation are linear. If there were contradiction like this, nobody will be using vector arithmetics. (Also similarly one can deduce a=b for any number a,b - the secret is dividing by zero which is packed up with formula, it is hard to realize that it's actually zero)