Zeiss Ikon

An idea came to me this afternoon, concerning how small interplanetary spacecraft could be (even with a life support mod installed) with infinite fuel allowing constant boost. A lot of science fiction has revolved around one or another kind of long-term constant boost (Larry Niven's ramscoop stories and Known Space, Doc Smith's Spacehounds of IPC, John W. Campell's Arcot, Morey, and Wade stories, several Heinlein "juveniles" involving torch ships -- and there are surely more). Even in RSS, if you can boost from Earth orbit at a constant 1G and turn over halfway, you can get to the Moon in hours, Mars in around a week (at least when near conjunction), or even Neptune in a few weeks. Spend a year without turning over and you're at a high fraction of light speed and, provided you have a means to avoid being wiped out by a microgram ice crystal, the entire "reachable" universe (around 18 billion light years radius) is within a reasonable travel time. You wouldn't even need that much TWR to get to orbit; as long as you have about 0.3 it's enough to get off the runway (assuming you have enough wing lift), and then you can simply keep boosting as decreasing atmospheric pressure increases the efficiency of your engines. Of course, there is the little issue of having to keep the game running in, at most, 4x physics warp through hours, days, or even weeks of boost time. Is there a mod around that would let one use regular time warp while maneuvering, and/or closer to planets and moons than stock? Needn't run at extremely high warp; to get several weeks into a few minutes is only 10,000x. Alternatively, one might play with a burn time limitation -- is there a way to alter settings for one of the engine mods used in RO to allow engines to overheat after some set time, and then require a cool-down period?

Thanks, @swjr-swis -- I'll give that a try. Though by now I'm working on Fleetfoot V. Among other things, I've dumped the tail fins for wings, gone back to "Swept Wings" which have worked well in another save (though that one has FAR, so what works may not transfer well).

Well, since the scoring hasn't been changed yet (wait, I haven't looked back at top of thread yet, maybe it has -- I'll check after posting), here's this. It's actually slower than Fleetfoot III econ -- but it's heavier and has one fewer engine, so I think it'll score better. Let's see... Got rid of the, um, "hippy" fuselage transitions. Now it's just Mk. 1 and the side engines are in Mk. 0 stuck on the sides of the tail cone. OUGHT to be less draggy -- and I think it is. I could never get the three-engine version of Fleetfoot III to break through 350 m/s without diving, or stay there afterward. This one will cruise right up to it (though I still haven't gotten into the "sweet spot" above 380 m/s and managed to stay there). I did play with fuel distribution once I'd burned off enough to do so, to move the CoM a little further back and reduce the lift required from the canard, which helped a little more. So, that's 355.9 m/s at 10.8 T on only three engines. And I just noticed, that was in a slight climb. Score ought to be 1281, which is another small increment over my previous supersonic class attempts. I find I start losing both thrust and lift around 8000 m altitude, to the point I have trouble holding level flight (takes a 10 degree AoA at 180+ m/s to hold altitude). Diving from there can get me close to 400 m/s, but I can't pull out gently enough to keep from dropping down into the drag bucket again, and wind up back down around 360 m/s and that bleeds off due to drag. Sigh...

After all, only China is allowed to drop rocket stages on China...

That means you brought *just enough* fuel for your flight mass. One more sandwich, and you'd have come up short on the monoprop...

@HyperDraco Better go back and look at the scoring. As it stands, you're dividing by number of engines. Unless your twenty-four Junos can get you close to orbital speed or your design masses something above 60 T at speed, you'll probably score lower than my four-engine Fleetfoot III econ. Better yet, you might want to hold off design finalization until the scoring questions are resolved. @Laie I'm fine with tweaking the scoring formula, but I'm not sure what's the best way to do it. As noted above, as it stands, it's basically "how fast can you go at a given TWR", which winds up being more about adding mass than about going fast. One way i can see where you maintain at least some level of "looks and flies like an airplane" is to require a demonstration of the ability to fly with a pitch below 30 degrees above horizontal, at a speed below, say, 100 m/s. That'll require at least one more photo from "questionable" entries (nav ball and vertical rate indicator will provide the needed information). This rule would rule out the "engine and Okto" missiles and some of the ones from the original challenge that looked like a crossbow bolt, but wouldn't disqualify any of the existing entries (that I recall). Then continue to divide speed by number of engines, but toss out the mass multiplier. Doing that, Fleetfoot III econ would score around 125, and Fleetfoot III (the 5 engine version) would be close to 120 -- and the temptation to add a bunch of ballast to the latter and refly would be removed. In fact, there'd be a slight incentive to build light, as a lighter aircraft can generally go faster on the same power, other factors equal.

I used the "start of burn" mass displayed in the dV pop-out in 1.8.1, which, by experimentation, I determined was the current mass, as opposed to any past figure. IOW, if you've burned off a third of your fuel, that display will have updated to reflect the wet mass with that fuel gone. Rules call for mass at the time of the speed confirmation screenie -- because as your mass drops, the induced drag (due to lift) will drop as well and your aircraft will (very slowly) pick up speed as it gets lighter.

Okay, I can't help myself. The bean counters over in the admin building were complaining about costs -- while Mission Control was still going on about getting a higher score. "Okay," says I. "Let's improve the score." Meet Fleetfoot III econ, the (very slightly) reduced cost, reduced fuel consumption model. "But it looks the same? What did you change?" I replaced one of the Juno engines with a tail cone (it's actually a nose cone installed backward, but don't tell Bill, he's a little OCD). "But it has less power, won't it be slower?" As a matter of fact, it is -- about 20% slower. But with 25% fewer engines, that's a net increase in score, unless that Juno is a lot heavier than I think it is. Okay, that's 502.8 m/s at 10.0 T on four engines = 1257. And now I'm done for the day. Really.

I spent some time on the revived/revamped "Fastest Juno-powered Airplane" challenge. My first entry was somewhat lackluster, in that it couldn't get anywhere near the speed of sound, so I went back to the drawing board. The second did better, but not enough better; the third was the charm. Fleetfoot III got up to 600 m/s in level flight at a weight of 10.2 T, with five Junos doing the hard work.

And I'm going to call that a good decision. This is Fleetfoot III. Fleetfoot III needs a bit higher speed to get off the runway than Fleetfoot II; at 10.7+ T and with not much more wing area than Fleetfoot B. However, it's got significantly more thrust. Five times as much as Fleetfoot A. I accidentally got above 250 m/s before remembering to retract the landing gear! Far from needing to dive to get past the Mach drag peak, it just powered right through in level flight. I recall reading that the Shock Cone Inlet was the lowest drag part in the game, so I used it, along with lengthening the fuselage and doing the Kerbal thing: adding moar engines! I haven't tried flying this without SAS, but it's as steady in Stability Assist as you could ever want; it'll fly for minutes with no attention, having only the slightest tendency to nose down over time. I had to play with which tanks do and don't get fuel to get the CoM not to move too much, and even so, it'll lose some longitudinal stability as the tanks near empty -- but you can see it has pretty good duration for this kind of airplane; 2600+ seconds is over forty minutes of flight time with some reserve for landing. And how does it perform, and score? Let's see... Fleetfoot III was actually still accelerating, slowly, but the rate had gotten so low I doubt it would ever have made 620 m/s. So, let's see... I get 600 m/s, times 10.2 T at the time of this frame, over 5 engines, gives a score of 1224 in the supersonic class. I'll call that good for today.

Hmm. Was just out testing Fleetfoot II. A vertical dive from 10+ km let me get to around 360 at 4500 m -- but it was then time to start pulling out to avoid crashing into the sea, and the combination of pullout and thicker air brought the ship back down to 270 or so (it got back to 330, and will max out at 340, in level flight below 1 km). Might need to try a shallower dive to give more time to accelerate before getting too low. I'm thinking I'll just go ahead with Fleetfoot III rather than spend a lot of time trying to tweak Fleetfoot II any further.

I'd have to dive pretty steep and long to get this one supersonic. Is there a drag reduction somewhere above 350 m/s? If so, I might fly it again and try that. Meanwhile, I've just been testing Fleetfoot II, a four-engine Mk. 2 that can get 340 m/s in level flight -- if I gain by getting supersonic, I'm confident this one can get there in a dive. It's also around 3x as heavy, so should score better if I can get a bit more speed out of it. And I've already got Fleetfoot III on my mental drawing board.

Okay, this craft (I call it Fleetfoot B, third version, though the first was about the same speed) is 100% stock, 1.8.1 with no BG or MH parts. It masses 2.7 T at takeoff; it'd be 2.4 T with empty tanks. Single Juno, takes off from the runway. I haven't tried landing it, because I suck at landing in game. I got 245 m/s in level flight, so I calculate that as 245 * 2.6 (with mostly full tanks)/1 = 637 -- not spectacular, even for the subsonic class. I may need to work at this a bit...

Hmm. This is interesting. Just opened my stock 1.8.1/MH/BG install and started a sandbox (didn't have one yet), now heading back to top of thread to fine-read the rules...

Really? I've had "oxygen depleted" messages from TAC-LS in 1.6.1/RO when a pilot had gone EVA from a landed airplane for just a minute or so. Maybe a setting?

The rule of thumb seems to be that the shorter your orbit period, the harder the rendezvous. This is because if you match orbits and try to close by burning directly toward the target, your path will be warped by orbital mechanics, and the longer it takes to pass through a given angular fraction of the orbit, the less effect this will have. If you're in a thirty-ish minute orbit around Kerbin, even from one kilometer this requires near-constant correction (and it's noticeable from 300 m); if you're in a two hour orbit, around either Kerbin, Mun, or Minmus, you'll hardly notice the effects at a kilometer and a five kilometer initial encounter is quite manageable as a starting point. In addition, the lower your orbital velocity, in general, the smaller the delta-V requirement for the final match when you reach the intersect. And if you're in a Kerbin year orbit around the sun, if you're close enough to get a target marker you can see in the sky (not just in the nav ball), you can just burn straight at your target and need minimal correction. But the kids will figure that all out once they have multiple vessels in space. For an initial craft, if launching from Kerbin, I'd still suggest a direct ascent for Mun or Minmus. Add a thousand m/s or so to the transfer stage (or another stage) and you'll be set up for a Duna transfer in window and Ike landing (though the return might get dicey -- best plan to use the transfer stage at least to get to Ike parking orbit). Duna's gravity well is enough deeper (not to mention the troublesome atmosphere -- needs LOTS of parachutes, but vacuum engines suffer significant performance loss) that Ike landing would be strongly preferred over trying for Duna's surface, and landing on the Mun is good practice for landing on Ike.

For the Mun in the stock game, direct ascent is the easy way to go. If you can, design the craft with Kerbal Engineer or MechJeb, so you can see your dV as you come down each stage. My current rule of thumb in 1.8.1 stock (the dV from orbit to orbit hasn't changed since 1.4.5) is that I need 3500 m/s to LKO, 850 to Mun flyby, 300 to capture and lower the orbit, 1600 to land and return to orbit (which has a good margin for a non-hoverslam descent), and another 300 to get from Mun orbit to a reentry at 36-40 km. Of this, at least the ascent and return needs to be in the lander (or its upper stage); otherwise it works well to stage at least once before LKO insertion, and once either just after trans-Munar or before Munar descent. This can be done with a Mk. 1 pod, Terrier on the lander, and Swivels for the first and second stages (side boosters can be either Reliants or Thumpers). You can build this before you unlock any of the 90 science tier.

An equatorial orbit requires a (costly, in delta-V) plane change, either as a dogleg during launch or after reaching orbit, for any launch site not on the equator. An orbit at equal or higher inclination to the highest latitude of your launch site choices will allow launching direct from any of the sites. There is still some dV cost compared to launching due east, but it is less than either an equatorial dogleg or an on-orbit plane change to equatorial from the same latitude. In other words, if you launch from the equator, and want to make it inconvenient for other programs to reach your station, put it in equatorial orbit. If you want to make it easy for them, incline it at least as much as their launch site latitude.

There's a Horten 209 in the upper part of the thumbnail frame. That twin-jet, flying wing bomber was built almost entirely of wood.

Ekranoplans don't work correctly in either stock KSP or with FAR mod. There's no ground effect. I hear there's a mod that does provide ground effect, however, but the one WIG craft I've seen here on the boards was entirely capable of flying out of ground effect. I might have to install that mod in my RO and see if I can design ekranoplans that actually require ground effect...

Yep, I'd far rather rescue new pilots, scientists, and engineers, and get paid to "recruit" them, than have to pay through the nose to hire them. One of the big issues with RO is that the Original Four retire about the time you could reasonably make your earliest (uncrewed) orbit, and it costs as much to hire a single new Kerbonaut as it would to upgrade one of the Space Center buildings. And there are no rescue contracts in RO.

You are correct. You'd get a pressure gradient due to the centripetal acceleration, both in the fan housing and in the return duct, but you'd get no flow beyond startup and shutdown transients as the "spin gravity" rises and falls. You'd probably also tear up your mounting system, because the duct would imbalance your erstwhile squirrel cage blower beyond the ability of the bearings and struts to hold it in place.

It's important to remember that Star Wars is not science fiction. Even in 1977 when A New Hope hit theaters, Lucas was calling it space opera. E.E. "Doc" Smith (one of the greatest space opera authors ever) had only been dead a few years at the time, and the Perry Rodin books were still being translated into English. Space opera doesn't depend on science in any way: it's action/adventure with blasters instead of pistols and submachine guns, starships instead of airplanes, and a society commonly more like 18th century Europe than any reasonable outgrowth of our modern world. Nothing bad about that -- space opera has produced some great works of fiction (the Lensman series, for instance, or the Barsoom stories). Just don't confuse it with science fiction.

This is correct. The ISS is in a 53 degree inclined orbit, because that's the latitude of Baikonur Cosmodrome. NASA can launch into that orbit from Kennedy Space Center, SpaceX will be able to do so when they start launching from Boca Chica, ESA could (if they choose) do so from Kourou (effectively on the equator). And, of course, Roskosmos can launch to that orbit just by launching east (at the right time). Everyone except Roskosmos gets two windows a day, one north of east, the other south of east (for logistical reasons, as far as I know, Canaveral launches use only the southward path and Boca Chica will need to do the same for range safety reasons -- can't have even a little chance of a failed launch coming down in Georgia, after all). Roskosmos gets only one, because they're at the northernmost end of the orbit. The same is true of launches bound for the Moon, BTW -- it's roughly in the ecliptic, 27-ish degrees from the equator. Canaveral is just barely south of that latitude, and can launch to the Moon's inclination once a day in a window, as I recall, an hour or so long; launching any other time would require a plane change that's prohibitively expensive.

Given the limitations of the user controls in the game (reasonably adequate for VTO rockets, even for Mun/Moon landings; much less so for aircraft that really need four-axis control all the time), I don't consider it "cheating" to design and test aircraft in an environment with reverts and respawns (like Sandbox, even). I've built two airplanes recently in my current RO career; one a basic science gathering craft using only starter-node parts, the other a transonic X-1 equivalent that requires the X-1 cockpit and rocket engine, in the first-tier aviation branch. The latter takes so much runway to get airborne with full tanks that the testing that approaches all-up flight has to be all-up flight, because there's not a chance of getting a rejected takeoff or bunny hop stopped again without going into the sea (or into the hills on the other end of the runway). Neither design could have been developed to their current "flies good!" status in a no-reverts, no-respawn setting. I'd have been out of pilots before either plane got off the runway for even a bunny hop, and hiring more Kerbals would have bankrupted the Program at that stage. All that to say, you're doing this the hard way. Learn to build and fly airplanes in KSP the KSP way (i.e. by blowing stuff up and respawning the killed crews) before you commit to no-reverts, no-respawns play.