The_Rocketeer

I'm talking about things I don't know about, but I believe when air-breathing/jet engines are over-speeding the thrust drops off to a flame-out. The best speed you can get out of an engine is not usually at it's max thrust, it's something a little after when thrust has decreased and drag increased to be equal. At max thrust, your aircraft would still be accelerating, so drag would gradually increase. By the time they're balanced, you're exceeding the max-thrust velocity of the engine, so its thrust has reduced. I think that makes some sort of sense... doesn't it?

The problem is probably because your payload's drag force is too high compared with the rocket's drag force plus steering force (which could be reaction wheels, control surfaces or engine gimbals, or combination of these. Top drag is unstable, whereas bottom drag is stable (like a thumb tack standing on it's flat end vs on it's point). It goes away at higher altitude because the drag falls off as the atmo gets thinner. I'd recommend, instead of standing the payload on top of a big rocket, try slinging it between two slightly smaller rockets. That way the drag force becomes much lower relative to the CoT and steering force, which give it much less leverage to tip you over. It's a bit like the difference between sitting on a unicycle vs sitting on a swing.

Here's an attempt at the top spot on the speed circumnavigation. I haven't quite got it here, much depends on getting the speed and altitude just right and in this run it wasn't, plus landing was... exciting. But I got down on the runway... more or less... I call the craft the Etherium IId. The time was 39:03. Edit: there are no pictures of the landing because I was too scared, and the F3 log distressingly says I lifted off at 0:38:53 or something, but I SWEAR THAT WAS A BOUNCE!

Slashy, I expect you to answer these questions, not ask them...

No, but you can move the camera around the build area by using/holding the mousewheel in combination with the alt key. Might help to back the camera right away/into a corner. Also u can use ctrl-Z to undo build modifications, might help fix unwanted mistakes.

Well, it could be this VTOL is intended to be flown like a helicopter and not like a plane, it certainly doesn't look like it has a lot of lift for it's size. Possibly horizontal speed is the issue, but in that case you would still need to fly it as though it was a helicopter, by tilting forward to gain speed, sideways to turn etc, before shutting off the aerospike. If I had to guess tho, I'd say the aerospike is serving the purpose of the main rotor on a chopper and turning it off is bound to have the associated consequences.

Not that I crave recognition in internet forums , but... do I go on the leaderboard now?

I made 1732.9m/s with a single engine and intake+precooler and no control surfaces (using trim and thrust vector steering only). I actually designed this plane for the circumnavigator challenge (was going for the top speed run, but this design was found slightly wanting). I hit 1734m/s but like a goon I forgot to get the F3 screen before I returned to KSC no screens didn't happen I'm pretty sure I cud go faster, but I'm too tired for vector trim-only controls at the mo! I tried to fly fairly flat because without elevators it's hard to pull out of a dive and if I dropped down below 17000m at 1700m/s the intake is liable to explode. In the event it was more like a series of gentle swoops getting faster each time. I pulled a u-turn about 1/3 the way round Kerbin and flew home slightly slower, and then fudged landing on the runway 3 times and went around till I cud get down safe. Many screens below - speed evidence is no. 13.

Nice work Nefrums! I'm pretty sure the control issues are related to shifting CoM, due to all the Oxidiser mass being behind the CoL on the way up, and the abundance of lift and spread mass distribution on the way down. Shifting fuel mass forward is exactly what I would have suggested. Did you follow to my suggestions about disabling fuel feed? If so perhaps disabling fuel feel from the other forward tanks on the way up would deal with the problem. I started on a design evolution yesterday but then realised that 100 kerbs to anywhere is totally excessive (unless you're literally colonising :-p). I threw together a 48 seater that I might submit a variant of sometime soon. Drag is a big problem for Mk 3 parts whatever you're building - u can't add moar thrust anywhere without increasing the drag profile, and since all the engines have specific roles it's a nightmare balancing everything!

Call the KSPCK, we've got a serious case of neglect on our hands!

My Sea Dart - Supersonic Seaplane. I never heard of it before today, but I had some fun building it. This was a totally stock build, some creative clipping and use of radial intakes for buoyancy my only tools. Below is a bazillion pics of my demo flight. I hacked gravity to move from the runway to the water but apart from that it was all legit. Normal take-off, normal landing, then climbing run, then high-speed (supersonic - Mach 2! ) run, then tower-buzz, then some low altitude stunts round KSC - got very close to some of the buildings and at one point I was below 50m in a tight turn but I think I missed it with the screen - then high speed landing (~75m/s), then normal take off and landing to prove it wasn't broken, then taxi to shore for the big finale! Thanks for the challenge, it's been a really interesting one - much harder than I initially thought! Edit: for some reason the first 8 or so pics seem to be at the end. I've moved them on Imgur but not sure if it's reordered them on here. O well!

No worries Vegetal, at least you got her off the ground! I'm already working on a slimline version hopefully someone with an uber-PC will come fly her for me!

Well, I could have docked on less without much trouble, but the way I see it monoprop has only one purpose on a SSTO (docking), whereas LF+O are much more valuable resources. I'd rather have a large tank of mono and use it all than have to eat into my LF+O even for a few dV. Perhaps not the best strategy for high points I grant you Also, something not entirely clear from the pics is that the docking happened about 50m below the 100k mark. My station must've got tugged off it's 100k orbit by a previous docking, and it has no RCS aboard, so I used the Whale's RCS and pushed them both back up above 100k before I detached. I can't see why that'd be outside the rules since it used more fuel than otherwise have done and it's exactly what real craft, including the STS on one occasion, do for the ISS due to orbital decay.

Hot off the press: Have flown again this evening, total success (except reentry balls-up wasting LF). 18 Kerbs to 100x100 LKO. Total fuel spent: 155 Mono, 4924 LF and 3155 O (does someone have figures for cost per unit? Flying in sandbox so I can't just subtract recovery..) No deaths or damage. I called this the Space Whale 1a because I topped up the monoprop tank. In the event I didn't need the extra dV, but it also helped with the CoM/CoL gap. That's all. Ascent was straightforward, I adopted a 20 degree pitch from rotation, dropping to 15 degrees at 5000m and 10 degrees at 10000m to gain thrust. Slight underspeed caused an engine flameout. Consequently had to switch modes at suboptimal velocity, but completed ascent safely. Orbited once to phase for station encounter. Docked and stayed so for another 6 or so orbits because the sun had set at KSC and I prefer to land in daylight. Reentry was fine except the cockpit nearly blew up. I tried to keep the prograde tracking on for as long as possible, but lost faith at 20,000m with the heat bar nearly full (check the pics) and pulled up slightly. I think I must've had a better glide profile last time, because I also seemed to descend and slow much more quickly, and consequently had to spend an extra 400 LF or so cruising to the runway. In true Kerbal style, I had a horrible moment where I thought I was going to overshoot the runway or break off a wing, but managed to get the plane down intact. Notes to Vegetal: 1. Sorry I wasted the fuel, might've cost us a point or two. 2. The plane wants to roll off vertical when gliding, nearly ruined our day on final approach. I guess its because the CoM is higher than the CoL. Might be an idea to put the wings above the windows rather than below.

Haha, it's fair to say that not many of my designs come out quite so... gargantuan. I set myself the goal of an interplanetary SSTO for 100 Kerbs. Why in God's name anybody would want such a craft is their business. With an orbital refuel to brim the tanks, I reckon Jool is within reach, possibly even a Laythe landing and return. @Nich, speaking of which (above), is refuelling allowed, or are we really talking about a SSTD craft here? What about asteroid mining? If I drop a crew compartment for an ISRU and replace the docking port with a claw, I reckon I'd be in business... I'll submit a fresh attempt in due course, running out of free time today.

You can manually switch between 'surface' and 'orbit' speed displays by clicking on it (on top of the navball). Try manually switching at lower and higher altitudes and see if the problem really is 'orbit-mode' related. If so, bug (so report it). If not, probably movement of CoM issue as suggested.

I would have produced a better report but tbh I thought it was a basket case after the kraken attack. Honestly Nich, if you want to disallow entries on grounds of insufficient evidence that's totally fine with me I plan to repeat the flight anyway.

I agree on the nose-weight, it's on the tipping point of becoming an issue on this craft. I'd like my CoL slightly nearer the CoM to keep the drag profile down during ascent. Re-entry was warmer than I'd like too. I came straight in from 100km to a 10km periapsis, kept prograde and deployed all brakes, but the nose section got a thorough cooking. Also the PV panels under the tailwings got a bit warm. Fuel allowances were also either well judged or a bit risky. I drained the RCS dry by mistake (fortunately after docking) but I'd not left it on for more than 30 seconds or so. It seemed like there was plenty of room for more tho - were u using it for ballast? All in all, pretty good - not a failure

Well I had a go at the pilot award today in Vegetal's Space Whale 1. The entire flight was a success, met a station in orbit (100x100), re-entry successful, perfect touchdown. Then things got weird. The tailplane just started randomly losing parts as I was rolling to stop. Here's the F3 log: I promise I didn't go near the launchpad! EDIT: @SpaceplaneAddict yes, my desktop thought I was asking a lot too. Still, I love a white elephant I'll try to build something more sensible for you!

I fear I may have overdone this... I give you the SSSP 100 - Hostess Luxury seating for 96 passengers plus 4 flight crew for 100 Kerbs! Under testing she reached LKO with 4.5 tonnes (9000 units) of LF in hand, just about enough to reach either moon and return. Specs: Parts: 362 Tonnes: 336.6 (145.7 dry) Cost: 542,804 (519,589 dry) One test run, recovered at KSC, no death or destruction. I don't know what recovery at KSC nets these days (I did this in sandbox for it's own sake) but u can definitely deduct fuel cost (~22,000 since the tanks weren't dry). I think she's borderline to score positive (haven't done the numbers), but she's in a class all of her own Flight Manual (comes on the back of a bar coaster) Action groups: 1. Toggle all Whiplashs 2. Toggle all Whiplashs and all Intakes 3. Toggle all RAPIERs 4. Switch all RAPIER modes 5. Toggle all NERVs 6. Don't touch I just remembered it's broken (was supposed to set elevons to deployment for aerobraking but it's only set up correctly on one side) Also, Brakes will deploy AIRBRAKES as well as wheelbrakes as per normal. Ascent Flightplan: Pre-flight: Disable LF feed from X200-32 tanks (one each side). 1. Activate Whiplashs and RAPIERs (airbreathing) 2. Full throttle. Rotate at 110m/s (near the bottom of the runway, if you run off the end don't panic), pitch up to 25 degrees. 3. At 7500m alt, reduce pitch to 10 degrees 4. Maintain attitude between 10 - 15 degrees until surface speed approaches 1100m/s (around 21000m altitude). Use action group 3 to activate closed cycle RAPIERs and action group 5 to activate NERVs. Then enable X200-32 LF feeds. 5. When Whiplash thrust drops below 15 per engine (check one), use action group 2 to shut off Whiplashs and close intakes (reduces drag). 6. Allow SAS to hold attitude fixed until Apoapsis exceeds 50,000m, then switch to track prograde. 7. Circularise at approx 72000m. You should be almost out of oxidiser by this time. Shut off RAPIERs and use NERVs only for further manoeuvres. Re-entry Flightplan: 1. If airbraking from high eccentricity orbit, don't drop periapsis much below 40,000m or you'll probably make something blow up. USE THE AIRBRAKES. 2. If you have LF left over, transfer the bulk to the X200-32 tanks for best weight distribution. Use action group 2 to re-enable Whiplashs and Intakes (you won't need the RAPIERs now). 3. Final re-entry profile should be nice and shallow. Make retro burn from below 90km, set periapsis around 10,000m and expect to land about 1/8th of an orbit short of periapsis. 4. USE THE AIRBRAKES. 5. Don't steer too hard or you'll tear the wings off. 6. Take care to touch down gently in a pitch-up attitude greater than 10 degrees. This avoids landing on the nosewheel and minimises airspeed at touchdown. Final notes: The plane is very responsive to steering once it's shed its wet weight, and it's got a heck of a lot of lift. Despite its size, you should be able to land safely at 50-60m/s without fearing a stall.

Having fuel lines that 'loop' can cause issues with uneven draining - a simple loop would be tank 1 > hose to tank 2 > tank 2 > hose to tank 1, but it could be much more complex and still loop. In your case it sounds like u have three such loops that share a common 'tank 1'.

Ok, my strong impression here now is that you understand very little about how to plan orbital manoeuvres in KSP and are looking for a very in-depth explanation of how it's done. I recommend you forget asteroids for now and use one of the tutorials for intercepting another planet (of which there are many on youtube, google and here) and then try to apply that knowledge to intercepting an asteroid (which is actually much more difficult because asteroids are so tiny). Also, while I totally defend your choice to play using MechJeb for everything, as I've tried to explain, there are limits to what it can do. You may find that forgetting MechJeb and learning the old fashioned way is much more enlightening. Also, if you get a report that says some gibberish you don't understand, try looking up the key terms, e.g. eccentricity. This, for example, basically means how circular your orbit is (more eccentric is less circular). A simple solution: if MechJeb gives that warning, would be to circularise the orbit first and then try for the intercept/transfer. While the forum community will be happy to help with specific problems, I can't help but feel you're asking for a lot of help with things that you'd probably work out on your own with a bit more practice.

Thanks for clarifying, I'll probably make a submission sometime soon. What multiplier for Duna?

Yeah you're getting it. Trust your instincts, Luke. The reality is to get right to the asteroid and grab it u'll probably need to use a few of the MechJeb functions as well as a bit of hands-on control. MechJeb is, after all, a corner-cutting tool for saving time and effort for the mundane jobs, not a precise implement for remotely accomplishing everything that's possible in the game. Sooner or later you'll probably have to get your hands dirty. Also, as much as the community could give u step-by-step instructions for everything, isn't part of the fun muddling thru on your own? I promise you'll remember it better for next time if u found it out for yourself than if someone walked you thru it. In other words, it's time to start up the game and try a few things, see what works

Could someone summarise the points formula for me in simple algebra? I'm not sure I understand these bits: Also, what counts as 'rotated at a station'? Do I need to actually swap Kerb for Kerb, or just drop, or just pick up, or what?