GoSlash27

Something else to consider: If you're just going to rendezvous in LKO and land, it's generally not worth it to add more efficient rockets. Adding rockets carries a mass and drag penalty that's rarely paid off in the (roughly) 2 km/sec you actually use them. It's better for this type of spaceplane to simply use the closed cycle mode of the RAPIER itself. Best, -Slashy

foamyesque, Good to see you coming around to the notion that there are "hard pieces" But the SSTO piece has been done. I think the tricky bit will be doing these different jobs with a single design. Operating at or near sea level is a lot easier with a higher t/w, but an SSTO can't haul all those engines. An SSTO is going to necessarily be tall and spindly with nothing to help stabilize it. Not an easy design to land on uneven terrain with tight fuel. And so on... Best, -Slashy

^ What AeroGav said. A wing is a wing is a wing. The only practical differences are lift to mass and thermal rating, but wings account for a tiny percentage of the total mass. Moreover, BigS wings carry your fuel with much less drag penalty than tanks. If you have access to BigS shuttle wings, I recommend using them. Best, -Slashy

foamyesque, Clearly. Seems to me that you could just as easily try it as guesstimating by eye. If you think it's so easy to biome- hop, land on a mountain, and then SSTO to orbit then you should have little difficulty doing it. Best, -Slashy

Yep. But if you're using additional vehicles to explore then there's no point in making the ascent vehicle SSTO. foamyesque, I *know* that biome hopping on Eve is possible, as is flying to a mountaintop. I don't know if it's possible to do all of that in a single SSTO vehicle, I *seriously* doubt it would be easy, and I'm certain it's too risky a proposal to seriously consider when there so many cheaper, easier, and safer alternatives. Best, -Slashy

foamyesque, What? You're the one who insists this would be easy, yet I've never seen you or anyone else actually attempt it. Seems to me that if anybody "needs" something to do this, it's you. I'm not sure if it's even possible, seriously doubt it would be "easy", and have zero interest in trying it. Although, as I've said, I'm interested in seeing someone try... Best, -Slashy

foamyesque, Again, if you say so. But to be clear that's not what I need because I have no intention of doing such a thing. Best, -Slashy

foamyesque, If you say so *shrug*. I used to have an SSTO flying car back in an early version. I could fly it to the island runway with that much DV, but that was about it. Wouldn't have a really good feeling about landing it on top of a mountain, and it was designed for that sort of thing. Biome hopping Eve in a design like that may be *possible* (I really don't know), but I'm *sure* it wouldn't be safe or easy. I definitely would not plan a mission around such a notion, but YMMV. Best, -Slashy

Foxster, I agree. The entire point of SSTOs is that they can be reused indefinitely simply by refueling. If you're going to build a ship that can only launch from one place, then there's no practical reason to do it multiple times. SSTOs are heavier and bulkier than their staged counterparts, and that comes with a steep price tag. OTOH, people do a lot of things in this game for reasons other than practicality. Best, -Slashy

foamyesque. I'm sure. But doing it in an SSTO capable ship? That's a whole 'nother thing. I'm gonna have to see that one. Good luck, -Slashy

The trick to using Mk1 parts for SSTOs is aggressive aerobraking. Get the plane slowed down so quickly that it doesn't have the chance to overheat. Yes, the low heat tolerance of Mk1 cockpits is intentional. They're not intended for space planes, just atmospheric flight. Best, -Slashy

Yes... at the expense of dramatically reducing your DV to the point where you can no longer reach the top of the mountain. The high pressure at Eve sea level is a double whammy. As a quick and crude demonstration, say your thrust is reduced to 2/5 the value at sea level, so you have to reduce fuel to 2/5 the former value. That drops your DV from 7 km/sec to 3 km/sec at the original Isp, but remember that the Isp has also dropped to 2/5 the original value. Now you're looking at 1,200 m/sec and you're going to have a hard time climbing a mountain. That's not even counting the huge drag encountered along the way... I'm interested in seeing this proposition tested, but I don't think it will be nearly as easy to accomplish as you assume. Best, -Slashy Leafbaron, I think the point of Eve is that it's supposed to be ridiculously difficult. Sort of a Kerbal Kobayashi Maru. We can operate from Eve, but it's very difficult. Best, -Slashy

foamyesque, That might be a proposition worth checking out, but from *my* design philosophy that would not be the case. Any launcher I design for minimum cost and mass will have a launch t/w of 1.4 or less. If that's all it can do from 2 atmospheres, there's no way it can lift off at 5. I'm not even sure it's possible to make an SSTO with that t/w that can still SSTO and I'm not sure that even if I could do that that the DV from down there would be sufficient to climb a mountain. But again... it's a proposition worth checking out. Best, -Slashy

foamyesque, Maybe, maybe not. It all depends on what you're using for propulsion and your t/w for the final push to orbit. Going down to sea level means that even if you have suitable engines, they may not produce the thrust and DV needed to get you to a safe landing on a mountain. Even the act of getting from the foothills to a peak safely eats up a lot of DV. Eve doesn't make life easy on our intrepid kerbonauts. Best, -Slashy

I assumed that your payload was 14 tonnes. Based on that, Tylo's gravity, and the DV budget, my spreadsheet solves the reverse rocket equation for each engine. So for 2,270 m/sec, a Tylo t/w of at least 1.2, here's what I get: Terrier: 6 engines, 37 FL-T100 tanks, Stage mass 37.8 t Poodle: 2 engines, 5 x200-8 tanks, 38.4 t Skipper: 1 engine, 6 x200-8 tanks, 40.4 tonnes. I recommended the Skipper because it's the lightest and cheapest single engine solution. I'd actually recommend packing a lot more DV than that, and the Skipper has room for growth. Best, -Slashy

AeroGav, the lower the better for DV, but the quoted figure is for a 10km altitude. Incidentally, it's 2,270 m/sec from there, so you'd best pack some extra. Best, -Slashy

Aerogav, According to my numbers, you need a heck of a lot more than that to make 2km/ sec DV on Tylo. Assuming a payload of 14t and DV budget of 2km/ sec, My spreadsheet recommends a Skipper with an X200-32 plus an x200-8. If you fill up that last tank, it gives 2200 m/sec with a total mass of 39.3 tonnes. There are lighter solutions for higher efficiency engines, but they'd require multiple engines to do it. HTHs, -Slashy Spricigo, It's basically a reverse Hohmann transfer. You set Pe to just above the surface, then brake at Pe to arrest your horizontal velocity without climbing or descending. It's the most fuel efficient method. Best, -Slashy

AeroGav, You can shave a couple tonnes off of that by replacing the Poodle with an Aerospike. It'll have plenty of thrust, and you'll be able to add more fuel for additional DV without overloading it. Conversely, you can use what you have and perform a zero descent rate landing. You have plenty of DV for that approach. Best, -Slashy *edit* wait... that looks fishy. No way that thing is only 2 tonnes dry. I think MJ is misleading you on those DV numbers.

Okay, so I worked out designs for 2 mission profiles. Profile 1 departs low Kerbin orbit, retroburns at Duna, detaches a lander with a 5t payload limit and remains in orbit. Then rendezvous with the lander, recover the crew, burn for Kerbin aerobraking, and detach a recovery pod. Profile 2 is the same as 1, except the ship first travels to low Munar orbit, tops off it's tanks, and departs for Duna from there. The lander itself would use parachutes and a couple hundred m/sec DV for landing and 1300 m/sec for takeoff. This makes, with the 5t payload, a 9.2t assembly with 1 LV-909. The Profile 1 propulsion for the mothership has a few different masses/ price points to choose from . 3x LV-N. 33.0t, $33,000 1 Aerospike 36.0t, $9,400 3x LV-909 36.6t, $6,900 1 Poodle 36.7t, $5,300 The profile 2 propulsion is much simpler. 2x LV-909 19t, $3,200 HTHs, -Slashy

Duna generally favors Terriers and Poodles over LV-Ns, especially if you refuel and depart from low Munar orbit. I'll knock together a design for you if I get the chance... Best, -Slashy

@TheSaint, Interesting! I notice the left- handed bolt action. Are you a lefty, or was that one of your parents? -Slashy

Carrot, For any resonant orbit, the conversion between period and SMA is (n/d)^3/2 where n is the numerator period and d is the denominator period. If you wish to equally space 3 sats in GSO, your transfer orbit must have a period of either 2/3 or 4/3. If you're willing to spend more cycles in the transfer, you can tighten this up, but for the sake of simplicity we'll assume you don't want to do that. For a 2/3 transfer orbit, the SMA is (2/3)^3/2= .544331 of the GSO. Assuming a 3,463 km SMA for the GSO, this means the SMA of the transfer would be 1,885 km. Since the Pe is as much below the SMA as the Ap is above it, this would set the Pe at 307 km, which is inside the planet's radius. So instead, let's say we go 5/6 and inject one sat every 2 cycles. (5/6)^2/3 = .88555. .88555*3,463 km= 3,067 km. Pe is 2,671 km, or an altitude of 2,071 km. The math works the same way for a larger transfer orbit (4/3, 7/6, etc.) HTHs, -Slashy D'oh! I misread your OP and thought you wanted 3 sats instead of 4. Same rules apply though. 3/4, 7/8 (if you skip a cycle), 5/4, etc. The math works the same for all resonances and all gravity wells. Your Pe would be 435 km on a 3/4 cycle. Best, -Slashy

Der Anfang, More to the point, if your craft can only land in one place, there's not much point in making it SSTO. Best, -Slashy

I'd like to see a whole new family of 1.875m parts/ adapters and an art pass on the existing rocket parts. And propellers! Other than that... I'm good. Best, -Slashy

Abastro, Ah. I see... I haven't played around with those. Most of the props I've seen have been operated by jet exhaust and of course that won't work on Eve. I don't imagine that putting another step in between your rockets and propelling the aircraft is going to do you any favors in the Isp department, but I'll leave that up to someone who's familiar with those. Best, -Slashy