Tychonoir

I've never tried to control a plane with just reaction wheel, but it doesn't sound like it'll fly very well, what with aerodynamic forces and all. It does have to land and stuff, but maybe I'll be surprised. It should be noted that at sub-mach, it currently has more control than it needs, but when getting up to orbit, I find that the extra control is needed or I can maneuver at all. I'll give it a try, but even if I ditch the control surfaces, I'll have still have to replace them with wings to maintain the lifting area, no? So I don't really see any mass savings there. Yeah, the mono prop is pretty heavy at .3 tons, but switching to the orbiter is a bit of a pain. Unless there's other savings, it's not really worth ditching on its own. Of course, if it becomes the difference in getting a min-space plane or not, then sure. Here's a little more analysis, and possible weight savings: Engines: So far, trying to go lighter seems to point to ditching the rapier, since it's 2 tons by itself. The panther would be nice at 1.2 tons, but I just can't get the speed or altitude with it before needing rockets, and I don't see having the fuel to fire them early. When I add more fuel, then I need to add more lift, etc. and I end up back in the 9 ton range after all is said and done. The Juno's are half a ton together, but ditching them seriously gimps any endurance to do actual work. With a light enough plane I might be able to go down to just one. The panther is efficient dry mode, but again, lacks the power to get close to orbit even with afterburner. Maybe if the plane gets light enough. Whiplash has the power, but doesn't have the ISP for cruising around, similar to the rapier and almost as heavy. As for drag, the RCS ports do get some drag, but I've tried to be fairly minimal with them, and the single ports are less draggy than the 4-ways. The atmosphere analyzer isn't as bad as it looks for drag, but 1) There's no where else it will fit, and 2) It looks kinda cool there. There's a docking port jr. on the underside that probably causes some drag, but removing it requires a claw on the orbiter, and those things can be a bit buggy in my experience. EDIT: Oh, a bunch of replies while I was typing. I'll try a version with no rcs and minimal drag and see where that gets me.

I'm trying to make a small unmanned science plane mainly for use on Laythe as part of a larger ship. The idea is that it undocks and leaves orbit, flies around doing science, then returns to orbit to dock with the main ship. I've seen a number of small SSTOs, but they are usually just an exercise in minimalism, and can't actually do anything useful. For this mission, it needs to hold a bunch of science, have the endurance and control to fly around, land at various sites, and still get back to orbit, rendezvous, and then be able to dock. (I guess it doesn't have to be unmanned, but I'm finding them to be lighter.) Additionally, I'm trying to keep clipping and exploits down to a minimum. Oh, also using stock KSP. I've got a working design down to 9 tons, but now I'm stuck. I have a few candidates in the 5-6 ton range using various combinations of engines, but they can never quite seem to get to orbital velocity, let alone have some reserves. Current design features: 9 tons Rapier main engine - To get to orbit 2x Juno - For efficient cruising RC-001S RGU - Probe core that also collects science Service Bay: Various science Small Monopropellant - Docking, additional dv 2x Retractable solar panels - So as not to run out of power in orbit 2x Small batteries - Power reserves Liquid fuel: 300 units Lq/Ox fuel: 225 units (Lq unit equivalent) So, any ideas for getting this thing down to, say, 5 tons? Less? Is it even possible?