Reusables

Amazing video! I have a question, why did you limited the throttle during the ascent till 5.6km?

I got over 22.34% with this rocket: Quite surprised that high TWR can greatly improve fuel economy! I'll post this as an entry after adding wings to the second stage.

Well, the velocity difference is always -2(u+v) in vector when planet vel = -u & ship vel = v.

I think you got a mistake here: (-2u-v)-v=-2(u+v).

Hmm... then, please update the OP to include the unit (km). This one was confusing as you said: I thought this means the result was in meter. Besides, screenshots would be great for verification.

You reduced the amount of solid fuel, right? Because a Kickback surely can go much further than few hundred meters when fully fueled... (They can get to LKO on their own) Did it go supersonic, where most of the aerodynamic drag comes from? Also, would you post the screenshots of the test rockets?

Well, I don't care about it, because I'll abus- -e it. I'll apply this to a robust rover. Maybe it could work well as rover wheel! (+ tried lithobraking, fairing does survive 200m/s but the other parts often get ripped apart by the stress. Maybe it would work well with spaceplane parts which have high impact tolerance)

Shoot the mun and bounce intact. (50m/s bounce should be possible - would bouncing back to kerbin be possible?)

I thought I might need some weight over 50t, but just found out that there's no payload part which weighs that much... The most massive part which is neither fuel nor engine is 6.5t passenger crew cabin, as far as I can find. So there's no point for panther spaceplane as spaceship. I've been looking at it. I really liked it, actually I borrowed some designs and ideas! Probably I'd never come to the concept of recoverable rockets if you didn't post it. Thanks! It was great, and I guess it should work in current version as well. Though I think my recoverable rocket TSTO is more efficient as it's staged design. (I could get 380/t with 15t payload) Still it could be the case that lifters work better in 1.2.

While testing a pseudo-aerostat, discovered that fairing has basically infinite impact tolerance. It won't break apart as long as the base part won't. I think this means that one can cheat with fairings and abuse them as landing strut / splashing buoy or rover cover, as it is the lightest part with that kind of tolerance.

Wow, Skipper SSTO for lifting under 2t, in 811/t? This is far from my expectation, as I had similar one(skipper ssto) which was quite expensive. I'm going to try light lifters! (2t first, since I can't think of a way to lift something lighter than that)

Hi, I tried to make a streamlined VTOL cargo SSTO, but there was an issues in my mk3 engine design: Mk3 to 2.5m adapter holds too much LF+Ox, so it's going to be horribly big.. (Besides I just can't make anything look aesthetic. Begging for advice, please help me!) I have couple more questions: 1. Is there heavier and reliable hinge than Thermometer-OscarB hinge? I think it reached its limit. 2. I'm using airbrakes to swivel the engine-wing section, but it seems that it is pretty generous with clipping, resulting in pendulum motion. Is there something which can hold the engine? I want ones which can move 90 degrees, and strong enough. Added pics for more explanation.

I don't think 5s difference for spaceplane would matter much. The drag loss due to relatively low TWR should be bigger in most cases. For LKO station, 300m/s you gained is enough.

Oops, so you should perform speedrun (gain speed) on about 16km. You get to 1.2~1.3km/s while airbreathing mode, right? Also single Terrier won't work on the case, did you used 2 Terriers? Besides, Aerospike is indeed good choice for spaceplane engine; just land on the runway(launchpad) or you'll lose several bucks.

Did you placed the engines without symmetry? Or you mean the number of engines?

But in the case, it's hard to match CoL and CoM. That's fundamental problem of the design, and it diminishes the performance. Also it's just barely better than reusable rockets, I guess..

In my opinion, not pitching up at all won't worth it. I didn't experience cost of over 30m/s pitching up 5 degrees, and it means staying longer in low atmo which makes the ship easy to overheat. Also low TWR efficient engines could be used in this case. Typically it's Terriers, but sometimes even Nukes can be used.

I design mine 0.4 TWR, usually I don't bother with it much. 0.7 TWR is too big for that, and 0.4TWR for circularization is usually not enough. I forgot to mention that 'spaceplane' has relatively less mass. But I got your point, one usually don't need that kind of mass. Nuke & Panther could make great combination for long-range spaceplane. It's great for giant spaceships in 140t limit, providing lots of payload mass. It's just too big for usual applications. The problem on hard career is usually funds for upgrading buildings, it takes lots of time and effort. Especially, that R&D building takes a lot to upgrade to 3 tier. so I can't have much options with it. And I want to do it in relatively short ingame time. Besides, I don't think there's much to replace pre-existing parts after unlocking nuke. Those in higher tech which are useful to me are only Gravioli & Refinery, Relay dish and Docking port Sr & Structural parts. Other parts looks like cosmetic bits for me. The two prior ones usually need ships for its own niche, so the only thing matter is big structural parts for bigger station. Even then previois station can dock to the new ones with normal docking port. (Also it's not bad to have more stations, I think) Personally, many techs just look obsolete, e.g. precision propulsion. (those radial engines... ;-P) @Spricigo, is it about disposable middle stage? I can't exactly get the idea. Disposing empty fuel tanks didn't save much in my experience.

The mk2 cockpit is fairly draggy, so it could the performance. Though I think your ascent profile was the major problem, as you suspected. Any SSTO spaceplane is too draggy on low altitude, under 15km. So you should be going over there to enter level flight and gain speed. The optimal altitude should be in 18km~20km with Whiplash. You can gain speed rapidly till design limit of Whiplash, as drag is very low there. Expect speed of 1.2km/s~1.3km/s. (With the speed comparable to ) After that, raise AoA to 5 degrees and turn on the rocket engines to accelerate more and coast to space. If I remember correctly, 2 terriers should be enough for the gradual ascent.

Right.. Juno could be . And wow, 1.77t in 1322? I'm looking forward to it! Well, you need screenshots/videos for lifting payload to LKO. Were you talking about the mun lander? Besides, I can make a category for StageRecovery if you want.

Forgot about that! So I can launch something heavier with the tanks empty. Though.. I think it's simply inefficient. The second stage needs good amount of TWR which is unnecessary for spaceships. Also it has to be aerodynamic enough. (It has less mass) And Nuke is better than chemical engines if it's reused again and again. It takes less fuel cost in most case, and slight increase of payload mass won't impact the performance. I was considering mobile science lab with science experiments will weigh some mass, and landing it is needed to gain 10% science bonus. Though it won't be problem for spaceships launched without fuel(Thus max dry mass is 25t in my case).

Hm, that's right. It's just that it doesn't work in my case, where the goal is not dispose any parts intentionally. (Except for heatshields, separators and fairing)

It makes reusable TSTO trivial to make, which I don't like. Prohibiting recovery mods gives certain challenges on recoverable TSTO and makes rocket SSTO quite competitive. Yeah I meant exactly that. If the second stage circularizes quite fast, you can taxi the first stage back to the launchpad. Boostback might be possible as well if the second stage has good TWR. Oh, were they too heavy for their thrust?

IDK, I'm on mobile and using the values on wiki. It is clearly outdated..

Can't agree more. But when there is hard limit of 140t (before 3 tier VAB), so there is certain mass limit of the spaceship. Meanwhile, spaceplanes can get to orbit as SSTO relatively easily, so it's kinda like 'heavy spaceship in one go'. Now I realized that pretty much everything can be done with 140t. But mun landing with mobile lab can still be pushing. In addition, big spaceplane is also a mobile station. (Forget about crew transport, I think I won't need something like 20 passenger spaceplane) I don't think wing/landing gear weighs much relative to the whole mass. (Or isn't it?) ... And there are airbreathing engines. What about decoupling it once on orbit, and recover it later? But rocket lacks LF storage, so they most likely have less dv. My calculation shows that fuel cost more with chemical engines even with 0.6 kerbin TWR and 1500m/s. Reliable mun lander should have more than that, doesn't it?