Reusables

Wow, mk2 spaceplane to lift heavy cargo cheaply? Impressive! All conditions checked for General Category(III); You'll be added to the list.

You got great points there! Cost per launch of specific mission, and Reliability of the launch are important indeed. Here I neglected several factors in the calculation, and ignored important elements in gameplay. It was because the calculation gets really hard when I was aiming to do the whole calculation. It needs several simplifications to get the calculation to be actually doable. I think the same counts for calculations on real life, like scientific engineering. Here I'd justify mine with the reason I took these simplications: 1. It's hard to calculate with every parts involved, as working with those several variables is nearly impossible. (As those has effect on each other; selection of a part often prohibits/allows/mandates another part) 2. For disposable launch, launch profiles doesn't matter much as long as you are trying to perform efficient gravity turn (there is enough margin). I discovered this while trying with rockets which lacks dv&TWR just a bit. It consistently fails to get to orbit with any kind of profile. 3. Dealing with reliability is one of the hardest thing to analyze. It is heavily dependent on the player, as good pilot can deal with some unstable rockets. Also occasional mistake/error can ruin a plan, which is even harder to take account in. (Welp; Kraken is involved in here) Also, this is all about 'theoretical optimum' (I mean good enough bound here), so it is to determine how good one's rocket is & how good a specific part is. I'll list some problems of my analysis to solve/improve. 1. Adapters(Decouplers). This one is important element which consists considerable amount of launch cost. In the calculation, Reliant is definitely better than Thud(yes that thud), but it needs mk1 adapter which will cost a lot for a Reliant or get so much drag. 2. Mission profiles like asparagus staging and SRB-augmented liquid fuel launches. This one is significant weakpoint of my calculation, as (one of?) those are where practical optimum is located. 3. Combination of several rocket engines can work better than specific engine. Besides, I couldn't get this line: What do you mean by this? AFAIK, mathematics only give constraints of the lower bound of launch cost. Improving practical cost per ton is about mission profiles and design decisions. (I couldn't find the actual lower bound for any launch profiles, though. There's so much complex relations involved)

Wow, that's impressive! Only 60 funds for a decoupler? I totally forgot about those aerodynamic(?) decouplers. (It's in aerodynamics tab, right?) Then thud seems to be reasonably good. (As it won't be holding Thumpers safely) I think one can use it to augment Kickbacks on top tier tech. (I think Reliant is too overkill for small adjustments & there's the aerodynamic loss) Also it can be attached to the second stage, to give initial boost.

Though drag matters a lot for small crafts like that. In my experience, something like that gets 100~150kN of drag on transonic region, which is big enough to shave dv of at least 200m/s.

Well, unlike those answers above it's possible and completely feasible in stock. Takes just a bit more time on launch, and save funds. (I used to lift 20t in 1000 funds with this approach) Just make sure that the stage separation happens over 20km and the Ap of the second stage gets high enough so that you can have time to land the first stage. This one is much more inefficient launch, since it used high cost aerospike and TWR-lacking nukes.

Cheated to dive into the underwater, and took an underwater sample. I didn't know that this one gives another experiment, in the same words... The text is identical to the one from the surface. Now time to check... So, got two surface samples from Water! One from the surface, another from the floor! This one is done in sandbox mode, so don't know how it works in science/carrier mode.

You'll need radial decoupler which costs 600 each with Thumper. Or live with 3t dry mass and nosecone(240)... Also it has lower ISP, which means the LF tank cost needed for Thud to achieve the same dv can be lower than the cost. Thumper could be waste in this case, also considering the thrust. I think Thumper is only good as standalone. Kickback standalone gets way better thanLF engines with 2 Thumpers on the side. EDIT: Just realized that the setup given above is more expensive than single kickback. So no, unless you are planning to recover it, It's just useless.

Thanks _Rade! I tried adding another layer of solar panel, but that didn't work. Though, as you said the large reaction wheel seems to be the problem! It does seem to dislike clipping in my end, too.

Thanks for the great hinge! Besides, I have a question to ask: I tried to apply thermometer-RCS hinge and later solar panel-RCS hinge for my electric propellers, and got strange results. Identical two hinge gives different reusults. The prior one is faster and more stable than the posterior one. Though those are configured in same way. Each propeller has a hinge on the front and another on the back. Here's the internal view: The posterior one is oscillating more. I found that the RCS on this one is penetrating through the solar panel for the prograde hold. Can't find why. This bugs me so much, as the assymetry will cause the craft to roll. Any idea why the two identical hinges are getting different result?

So it's spaceplane with drop tanks&engines. I think you can add some fuels and streamline the plane so that it would be fully reusable SSTO. Won't take much more time than disposable planes.

I found that combination of 2~3 LFOx engines could work better than sticking to one kind of engine, in theory. For instance, There is poodle&Spark for circularization stage which gets reasonable increase in TWR while the ISP and the cost don't get much effect. I'm quite sure that this is applicable to the real KSP. I'm going to update the spreadsheet with these engine combinations. By the way, just found that O-puff is cheap engine with great TWR. (Only cost 73.575 per 1t weight of thrust, with TWR 22.65) It might be worth it for low dv operations.

If only the terrain fix is about fluctuation of the surface including runway... hype. (I'd like to see just a small bit of procedural work here for the smallest scale) EDIT: Just found out that runway fix is just about the modeling. So... I can't be hyped. Sorry for posting this.

So nothing can beat reusable spaceplane in any region. By the way, I added analysis for SRB on the spreadsheet, it clearly shows that for big enough payloads Kickback is the way to go for anow atmispheric stage. It's not for thrust augmentation for liftoff, though. Also switching into cost per thrust with engines from cost per ton.

I'm sure that this news is just a scam. There is no need for HST, since the visible region could be covered by ground telescopes with adaptive optics now.(Obviously cheaper&better) This is why JWST is going to be near-infrared telescope. Hubble can work with near ultraviolet and near infrared wavelengths, but it shouldn't be effective compared to the visible light. I think it isn't worth the maintenance cost.

First stage can be recovered in stock ksp. Just raise Ap of second stage high enough(80~90km), and in the meantime land the first stage back. Just some airbreaks and chutes needed if you don't want to do hard powered landing.

Wow, that looks really efficient! I didn't know that Skipper becomes good when it gets thrust augmentation. By the way, you used fuel tanks for payload(Rule 6), but obviously didn't use the fuel contained there in the entry. So I'll accept this one and change the rule to 'prove the payload mass is unchanged'. EDIT: this is what kept bothering me as well.

I found that it makes the attached nodes draggy like a blunt edge. I used a debug menu(Alt+F12) option of displaying the drag of each part. Radial spider may work better with offset. That's great idea! I'm curious if spaceplane can still beat rockets with these small payload. So how much does the fuel cost?

What engine did you use for the craft without fairing?

So it works with radial battery! That's really cheap craft. By the way, I think it could work with small nosecone & FL-A10 Adapter without fairing, if Ant had casing. But it doesn't, which results in the blunt end generating too much drag. If you are fine with offset, putting spider with the above configuration could work. There's no need for that, though. Also, the drag matters on the transonic region, which is why TWR is critical. (Still, gravity loss tends to be way bigger)

Made a light rocket to haul small contract satellite to orbit. This one uses Hammer for 1st stage. This one has 1.1km/s of dv to spare on LKO. Album: http://imgur.com/a/lVUAP

@rcp27, So I've made a craft which can get to orbit, with thermometer and mk0 battery to transmit the data. The first stage is Hammer, Total cost is 3646, and lifter cost is 1211. Album: http://imgur.com/a/lVUAP Craft file

So aerodynamics seems to be a problem with that. AFAIK 2km/s is sufficient to get to upper atmosphere witha reasonable TWR. (I got out of atmosphere with 1.6km/s) (Edited) I just recognized that Ant engine doesn't have aerodynamic cover, so it needs to be in the fairing. In this case, fairing is fairly better than using spark About the gravity turn, it works with constant thrust. I think no one actively control thrust to get to orbit, usually. Also didn't know that explosive decoupling doesn't work now. Great, you got the cost reduction! You are right about the fairing, I didn't know that Ant engine doesn't have any aerodynamic cover. Aside from that, the basic fins have low maximum temperature of under 1000K, and the other has max. temp. over 1200K. So you'll be fine with thermal issues here. Try a bit more aggressive turn. I think if you want to get the experiment, Z-200 is the best one without fairing. It's lightweight, so won't affect performance too much. I want to see what your gravity turn is like. Would you post some pictures of it?

So, you are going for highly inefficient trajectory due to the TWR of circularizing stage. If you don't have enough TWR to circularize(spends too long time), then you are doing it wrong. In detail, You should be losing over 600m/s of dv doing inefficient gravity turn, and lose another 300m/s performing circularization burn with pitch of 30 degrees. That's nearly 1km/s of lose! Also, 50% is way down for Thumper. You may as well use Hammer. Let's calculate payload mass and lifter cost here. Payload: Antenna(0.005t)+Probe(0.07t)+2xSolar Panels(0.035t)+Thermometer(0.005t)+Battery(0.01t)+Reaction Wheel(0.05t)+1 OscarB fuel tank(0.225t) = 0.4t Lifter: Ant(110)+2xOscarB(140)+Decoupler(300)+Fairing(300+)+Thumper(850)+3xBasic Fin(240) = 1940 So you are using 4850 per 1t of payload! AFAIK you can use less money to lift 1t. I think these improvements will cut down your cost to target orbit decently: 1. Fairing is too expensive and heavy for such a small payload. It'll cost over 300 and heavier than 0.075t, since cost and mass of deployed parts is added to the base cost/mass. If you are worried about aerodynamic stabilization, just put small nose cone(180, 0.01t). (You won't need it) (If it is for aesthetis, let me know, as it is reasonable choice for the purpose) + If you think aerodynamics is a thing, I can say it's definitely not. Definitely, the loss is smaller than 100m/s. 2. If you are aiming to do circularization burn with single Ant engine, just use single OscarB tank to get more TWR. Here are some calculations to verify this: Now, your dry mass of second stage is 0.27t, and its wet mass is 0.87t, thus it has dv of 3.6km/s. When you are on LKO with an OscarB tank fuel to spare, the wet mass of the stage is 0.47t. So you have spare dV of 1.7km/s. AFAIK that's enough to get it to Duna and Eve! Dv of 1.2km/s will be enough. (1km/s lets you escape kerbin) When you have single OscarB tank, the second stage has dry mass of 0.22t and wet mass of 0.42t. Thus initial TWR of 0.485 and dV of 2km/s. It'll be enough to do efficient circularizing burn(TWR increases over time). Considering 1km/s you wasted on gravity turn, and 0.6km/s of unnecessary dv, this one is only 0.1km/s short! Also the reduced dry mass will allow more dV for the first stage. 3. You are fine with single Hammer, as its dv is not that short! With the payload above, you need to launch 0.435t (including decoupler). Single Hammer has atm dv of 170*9.81*ln(3.995/1.185) = 2km/s. If you are doing efficient gravity turn, 2.8~3km/s is sufficient while going eastward. Thus 1~1.2km/s of dV will be left. It could be a bit short with westward orbit. If you want some more dv, just put something like Flea under Hammer, and explode it away. + If you want more dV, 2 Hammer with explosive decoupling will work. The lower stage gives dV of 775m/s more. The so the two Hammer has total dV budget of 2.7~2.8km/s with the payload, which can make orbit themselves! It could be a bit unstable, so some dV will be lost. Though it'll be still enough. + Probodobodyne HECS costs 650 and weigh 0.1t. So it's cheaper and lighter than 1 small reaction wheel + 1 QBE probe! The torque should be enough to turn such a small craft. (Also this will give you more spare dV) Also, why do you need battery? I know that Kickback is improper for this kind of thing. Also I think you're right about Spark. But, AFAIK, you can do explosive decoupling with Hammer. AFAIK, payload is something that can be decoupled from the lifter, technically. In my opinion, it is acceptable if you can decouple it by adding some decouplers. About recovery cost, it's included in reusable case, and excluded in disposable case. So it is disposable spaceplane? I thought you are launching it vertically. In the case, single divertless intake will work decently. (As speed gained with airbreathing stage will be near 1km/s)

Oh. My bad. (Apparently, English is not my first language;) EDIT: Also I'm nearly retarded at picking up humor.

Sorry, I misunderstood definition of community at the moment. If I remember correctly, they were looking for assistance for localization, which is what I meant when saying about 'proofreading'.