Anton P. Nym

Well, you could... but it's tricky and takes several orbits. You have to "pump the swing" and thrust when you're on the opposite side of the orbit that you want to adjust, then cut engines and coast until you're back to where you thrust before and burn again, and repeat until you get the orbit you want. As I understand it, that's how they work in this mythical "real life" place people talk about. I'm not patient enough to wait for that, so I use a chemical (or nuclear) rocket to get into an escape orbit and jettison it afterward. I'm using the ion engines for course corrections and circularising orbits once a probe is where I want it... but I'm still exploring how that works. (Particularly I'm wrestling with how inaccurate the "Estimated burn" clock is on low-thrust engines. It's hard to time very long burns with the estimator built-in to the maneuver node system, and ion engines are all about veeeeeeeeery long burns.) -- Steve

So far I have few complaints; most of the designs I tested that had trouble were probes that relied on the pod having gyros. Since they don't anymore, that's expected behaviour. I'll write those probes off and start anew. The only design that perplexes me is the RATO I used to boost a solar glider in 0.20 now induces a consistent slow yaw to port that will plant the glider firmly into the VAB's door unless I jettison the RATO early. Since the RATO had no guidance logic or control surfaces, I guess this shouldn't surprise me; I'll do a quick redesign with some fins and see if the problem persists. -- Steve

I'm typing this while running a 1hr 32min ion engine burn designed to get a small probe into an aerobrake with Duna. It takes a long time, yes, but the fuel burned in this maneuver is too light to bother measuring... making the booster I used to get the probe this close a lot lighter. Of course it's not as good as some of the modded engines out there... I think I'll close out this 0.20-era game-save with another try at getting an Orion nuclear pulse rocket out the same way to see if the new SAS/ASAS treats it more gently than the previous Kraken-bait version did. But I've also made a glider probe with solar-powered four ion engines that I can use to "kick" it up when I need to climb, and (I think) it can fly on Eve for as long as I care to toodle it around. -- Steve

Taking another look, the design starts of slightly top-heavy (centre of mass is ahead of centre of lift/pressure), gets less so when the side boosters drop, and then gradually more so as the Big Orange Booster empties. If you got out of atmosphere in time you'd have no problem, but it looks like you're still in atmosphere when the design goes back to being top-heavy and then your rocket tries to fly like a plane... a plane without wings, that is. Adding reaction wheels above the CoM mitigates this but make the top-heaviness worse... so that's why you're seeing limited results. Add in that reaction wheels aren't as powerful as the old "shake-rattle-n-roll" SAS and I think that's why your design doesn't work in 0.21. Removing the upper fins would help move the CoL back behind the CoM, increasing the rocket's stability. That might be enough to get you out of danger all by itself. If not, maybe try canards in place of the aft-most fins and give the new ASAS more to work with... though as I haven't played with 0.21 yet that's a guess. -- Steve

When I get 0.21 loaded, I'm going to try two quick designs with reaction wheels and the new SAS systems; one conventional design (with the axis of thrust pointing through the CoM and the the CoM below the CoL) and one that my old model rocketry experience says is unstable near the end of its burn but worked in 0.20. If the former works like a charm and the latter pinwheels like it would here on Earth I promise not to complain. -- Steve

Almost certainly a power issue. You need solar panels or radiothermal generators to supply power to your craft when rocket motors aren't firing, or enough battery capacity to last through times you're coasting. I usually go with a couple of lightweight (fixed) solar panels and a small battery to tide the probe controller over when the panels are in shadow... but that may change with the new version which needs electricity to drive SAS/ASAS modules. -- Steve

I know 0.21 changed how pod torque works but I don't have details. I gather SAS is now replaced with reaction wheels to add countervaling torque, and that ASAS is now more like a fly-by-wire system than an autopilot. I suspect I'll have to revisit a lot of my designs when I get a chance to install 0.21. -- Steve

Not really. The TF39 turbofan engine for the real-life C-5 Galaxy has a ~250cm diameter, or roughly the same diameter as a KSP size 2 engine. There are no size 2 jet engines in KSP that I know of; the size 1 engines there are about half that diameter, and so only draw (as a rough approximation) a quarter the air. The Galaxy has 4 TF39s and each would need to have 4:1 intakes (16 in total) to match. Air flow scales roughly by the square of the diameter; 60 intakes per pod would only need each pod to be 7-8 times the diameter of a size 1 engine... which isn't terribly far off, given the picture. -- Steve

I kludged a solution by using the "long" decouplers as the main junction, then putting the hydraulic manifold decouplers fore-and-aft of those. The side boosters clipped to the long ones, and then I connected the hydralics to the side boosters with struts. It makes separations very pretty, like the ship's throwing confetti to celebrate a successful launch... but it's probably not necessary, and using straight struts would probably work as well and save on drag and weight. -- Steve

I'm testing an interplanetary space tug; a Rockomax double-sized tank feeding a pair of the FL800s with LV-N rockets. I fly up a probe, the tug then docks with the probe and (hopefully) does the planetary transfer burns for the probe. If I've done it right, it's currently hauling a sample return probe to Duna and back. This saves hugely on launch weights for the probe, and if it works I won't have to worry about discarded planetary transfer stages roaming the system when "Era 21" comes around and makes my current debris-cluttered save obsolete. -- Steve

I use a simple expedient of putting a proportionate number of RCS packs depending upon distance from CoM: if one ring of RCS is "x" distance from CoM and another is "2x" away, I use twice the RCS packs on the first. It mostly works, though of course the current ASAS isn't terribly happy with that arrangement. Modulating the thrust would be more elegant, of course. That, or introducing RCS packs of differing strength... but that way leads to parts-madness, I think. -- Steve edited to add: Or could RCS strength be one of the "tweakables" coming in a future update?

I'll start a new career and consider the old one to be "in simulation" for the "real" space effort. And I'll take another crack at making an Orion drive spacecraft as maybe the improved ASAS won't cause that 8000T barge to shake itself apart when maneuvering in trans-Minmar space. -- Steve

I got a reasonable-looking 5:1 (and a later mark with 6:1) using the radial intakes, without clipping and with semi-plausible air flow. I try to make my spaceplanes not obviously absurd.... ....well, usually. (My defense in this case; there are no stock ducted air fans or propellers in the game yet, particularly none driven by electricity, so the only stock option is ion engines for a solar-powered plane.) -- Steve

They said I was mad... but the Arro Ghost flies. Well, more "glides very, very well" but it still made it out to the island airstrip from a 2000m release using no fuel other than a few grams of xenon. Needs work, but I may have figured out my probe program for future Eve missions. -- Steve

Yes, but a NERVA upper stage curiously doesn't, and it's a low-thrust/high-I(sp) engine to boot. The probe body I used only had 5 internal battery, so I lost control of the probe early in a 15-minute burn and didn't regain it until after the probe had left the eclipse and Kerbin's shadow; by that time it was headed off into the Oort cloud. -- Steve

*sigh* -- Steve

Glad to see the progress made! I look forward to giving it a try on Big Stan mk V. -- Steve

Weirdness, and I'm still new enough at KSP that I can't tell if it's the mod or the kraken. My revision for Big Stan worked very well in Kerbal orbit, with nicely controllable pitch-overs (a bit sloppy some times, but I gather that's me botching it) but when I try for maneuvers that take her into transplanetary space she becomes completely uncontrollable. Pitch-overs (or yaw-overs, I was desperate enough to see if there was a difference) somehow transfer motion to the roll axis about 60 degrees into the maneuver, which kills the pitch- (or yaw-) over apparently because the whole thing becomes a huge gyroscope. At some point roll will escalate out of control (or frantic attempts to kill the roll will end up in a tumble) and then the parts start shedding. Towards the end of testing I noted that there was a lot of trembling happening when using ASAS (even without RCS or NERVA gimballing active) and I'm just not good enough a pilot to kill the tremble manually. Adding additional SAS modules didn't damp out the trembling. I think I'll shelve Big Stan for the weekend and come back to the design with fresh eyes next week. -- Steve

It just struck me how blase I got... talking about a test run using 100km/s of dV to "do doughnuts" in a Kerbal parking orbit. Orion (particularly with the big 400MN charges) does mess with your sense of perspective. -- Steve

I'm testing that now with a new revamp; same broad design, but lightening the NERVA outriggers and adding many more struts. I'm running a stress test on it now, lighting off a bunch of 400MN charges then doing a rapid RCS turn-about burn and lighting off an equal set of charges to put maximum strain on the craft. So far it's held up under 100km/s dV of this, plus some extended NERVA burns up to emergency thrust. (I took a screencap but haven't uploaded it yet; I'll get on that after work.) If this stress test fails, I'll consider doing a big trussed-out pontoon arrangement mounted to the magazine stack or something similar, but if I can I'd like to keep the layout as it's surprisingly maneuverable for a giant ingot propelled by huge explosions. -- Steve

Updates on ol' Project Dunaboom here: http://anton-p-nym.livejournal.com/546267.html (phase 2), http://anton-p-nym.livejournal.com/546907.html (phase 3). TealDeer; uh, you know it's bad when you see Jebediah losing his cool. (Not a problem with the Orion itself, but an undetected error I made laying out struts.) In the spirit of KSP, however, Project DUNABOOM II is already in progress with improved strut layouts. It'll be a stripped-down mission with just one lander, to prove out the main design, but it will proceed. -- Steve

At the risk of spamming, here's a link to my overly-wordy write up of the first phase of Project DUNABOOM, Big Stan's voyage to Duna. http://anton-p-nym.livejournal.com/544267.html As a teaser, and because it's so pretty, here's a picture of Big Stan circularising her orbit. As I noted in my blog, this is about as close as I'm going to get to being Chesley Bonestell. -- Steve

Hi! New guy, came in with the Steam sale; I've been interested in rocketry since infancy (I'm barely too young to remember Apollo) but it took me a while to get on board the KSP train. Wish I'd found this forum earlier; that'd probably would've made my early landing attempts a lot easier. Most recently I've been messing with Nyrath's "Orion" mod with highly photogenic results: I will probably post more later... apologies in advance. -- Steve

Thank you. It was a blast (er, figuratively) to put together. Great! Look forward to it, if it indeed can be pulled off. Yeah, it turns out de-tempering the steel of an armoured plate designed to withstand nuclear explosions is a bad idea. (Writes out on blackboard 100x) -- Steve

I'm rather new to the forum, and have only played KSP since the Steam sale, but the above is my second cut at using Nyrath's Orion mod the KSS Stanislaw Kerman. It's intended as a persistent ferry for interplanetary missions; hence the 5 docking ports (one shielded axial port into the flight deck, 4 mounted radially below a Hitchhiker module) so that I can just fly up the right payloads for each mission. Primary propulsion is ol' Boom-boom, fed by the 600x3.5MN magazine stack plus 60 each of the .88MN "trimming" charges and the 400MN transplanetary injection charges. Secondary propulsion (also acting as secondary attitude control thanks to thrust vectoring) comes from 6 NERVA engines, each fed by 3 FL-T800 tanks topped by SAS gyros. (I had to mount the NERVAs away from the ORION's hull, as otherwise the NERVA exhaust impinged upon the pusher plate with, er, less than entirely salutary results... I figured the Kerbal solution would be to add more fuel instead of putting them on pylons.) Primary attitude control comes from 18 RCS quad-blocks fed by a small ocean of hydrazine (4x FL-R1 tanks below the Hitchhiker, 18x FL-R25 tanks set one apiece atop the FL-T800s); 6 blocks just below the flight deck, 12 near the base of the Orion's working parts about half as far from the Big Stan's centre of mass. Electrical power is provided by 2 RTGs; I figure with all the fissionables already aboard two more sources wouldn't hurt. When running alone they're largely superfluous, but when payloads are docked they can keep payload batteries charged and power the 4 docking lights I have mounted to make docking a bit less hairy. I've also festooned the upper areas with ladders to make EVA a bit less fraught. Alas my cunning plan has come aground slightly; I got a "bomb truck" tender docked to Big Stan before discovering I can't transfer bombs to the main stack; I don't know if this is intended or not, as it must be terribly awkward to haul those magazines around in freefall. If not, well, can I make a feature request? In any case, Big Stan is now in a 141x132km orbit of Kerbin while I refine some bugs out of its first payloads; a pair of Dunar lander probes, a pair of Dunar rover probes, and a big Dunar sample-return probe to rehearse landings on and take-offs from Duna. I have some more screenshots; I'll likely be putting them up on my blog later today. I'll sign off by saying that I'm having amazing fun with KSP, which is threatening to take over my life, and by thanking Nyrath & crew once again for an amazing mod. -- Steve