ExaltedDuck

I want to give it a shot but I haven't had a chance to play Kerbal in a few weeks.

Check the french language thread's scoring section. It seems to be that there are points available for either plane delivery or rocket delivery, and a bonus for re-usability (I think. It's a half guess. I don't know much french and it appears Google translate doesn't either.) IMHO it sounds like a fun challenge with a different enough set of rules and circumstances from the Elcano challenge to stand on its own.

Rapiers cut out at 1751.7.

I like it! Anyone who hasnt tried large craft for this challenge might not realize how much it ramps up the difficulty. But I know. I had to upgrade the administrative building to accommodate a whole department of temps tasked with writing letters of condolences to the families of my heavy plane program's pilots. They don't know I know, but the engineers have taken to calling me Cave Johnson behind my back.

Any cardinal direction is acceptable. Not many have chosen the polar route since the runway is oriented E/W and a fly-over of the poles is disorienting. I've noticed flying east burns less fuel and allows higher speeds but flying west offers a shorter ground track to cover. I think the entire cross-section of the atmosphere rotates along with the planet, so effectively the times are equal in either direction. Most participants have put up multiple entries, both to improve over previous runs and to compete in multiple categories. I think the rule is that only the best individual performance will be listed. Prior runs get wiped when you post an improvement. Welcome aboard, and have fun!

I did a little bit of testing and am disappointed to report that it seems there is a hard speed limit at 1751.7 m/s. I think if you're really lucky, you might be able to screencap a *very* brief glint of 1751.8 but I might have been seeing flashed to 1751.6. Can't be certain. Anyway, With that said, and the speed already hit by another competitor, I'm not going to go through the trouble of all the formalism of an entry just for a tie. I will say I have been there, however, and am thoroughly convinced nobody will exceed it.

I don't see any pics. Your altitude ceiling suggests rapiers but top speed suggests whiplashes. Not knowing more of your design, I'll offer some general tips: Excess air intake and weight/lift balance issues can drastically reduce cruising speeds by increasing drag. Lift too far behind COM results in a nose-up attitude in cruising which de-occludes your mid/rear-ship parts. Jets at high altitude can generally be fed by one inline intake like a precooler or half of a terminal intake like a shock cone. They have to be flown hard and fast to get enough air up there so pushing it close to melting between about 15000-20000 m is critical. With whiplashes, best speeds are usually found around 19500-21500. They will usually not operate over 22000 at full throttle (and offer too little thrust to be worthwhile higher anyway). Rapiers can run a little higher, often reaching the highest thrust to drag ratio between 21500 and 23500. Higher altitudes might be necessary to improve fuel economy, but a slow and measured climb is necessary to avoid losing speed. Getting the weight balance right to minimize AOA does a lot to ensure intake efficiency and line up thrust in line with the forward flight vector making everything a lot more efficient (and therefore faster) - - - Updated - - - Also, based on the numbers I'd guess you're running a somewhat fuel heavy 4 engine design. Best case scenario, youll need about 300-400 fuel per engine for a full circumnavigation and maybe an extra 200-300 for climbing. At 0.4 consumption, an hour of flight burns 900 LF and 0.9 consumption burns 3240 And initial ascent can easily cost 30-50% of the fuel you carry into a single circumnavigation flight (that is, the 30-50 minute cruising portion sips equal to double the amount that the first 3-10 minutes gulps down.)

I wouldn't be surprised if it could make it around multiple times. An aggressive ascent, slightly higher cruising altitude, mid-flight weight balancing, and maybe an autopilot to limit control input, and it might be good for an expedition badge. - - - Updated - - - Impressive, young Skywalker.

Part of me wants to say yes. Ok, most of me does. Unfortunately, it's also the impetuous side which doesn't want to spend more than 3 minutes figuring out a proper weight/lift balancing scheme and ends up with his nose 8-10 degrees up in the wind at a shamefully inadequate supercruise velocity.

1740 is plenty. My now-2nd-place plane (Pequod, on page 34 with a 38:44) was cruising around 1733-1735, IIRC. It would hit as high as 1750 on its way down, but that was only for about half a minute at the end. With a properly steep climb (doubtless with careful throttle control) and a late descent (more of a controlled crash, really), I have no doubt that your craft can claim the record.

Good flying, Rubisco. Whenever I've built anything with the airliner wings, they explode. I think it has something to do with my throttle lever supplier marking them with "off" on one end of the travel and "not enough" on the other.

Yeah, color me impressed, too. I had a fun idea for a basic jet challenge: Zero displacement rally scoring. That is, take off, go the exact speed of kerbin's rotation, and land it 6 hours (exactly 1 Kerbin day) later. Effectively, it would be lifting off to stand still while the planet rotates below. . That would be an average surface speed of, what, 174.5? If my calculations are right...

airbrakes can be difficult. I followed Helmut's example of using landing for drag in the upper atmosphere then used hard pitching maneuvers if needed to get speed down more. I tried to get down to around 1000 m/s from cruising altitude to about 10000 m then tried to hold as much of that 1000 as possible, aiming my nose short of the runway to bleed down to 300-ish on the final nose up, the use the chutes instead of a typical flair maneuver to slow to touch. Like I said, it gets dicey. - - - Updated - - - also, you might be able to get a few more m/s while cruising if you can afford to swap the big s strakes out for another wing type. On some of my faster crafts, I used big s elevons and elevon 5's as primary lifting surfaces (often with smaller elevons as canards). They get a bit tricky to fly, though, since they pretty much go from neutral to full deflection with any input (any slight adjustment can easily turn into 15+ g aerobatics. =D). The drag reduction wasn't always woth it. Having a small wing surface plus an elevon doesn't seem to lose much speed versus having none and just an elevon and you can see on my latest velocity attempt, I opted for a rather full wing surface (C? maybe... it's the large rectangular wing connector). If I were to do it again, I'd probably try the small delta wings or maybe a swept wing variant. My gut feeling is that it's more important to minimize the level flight angle of attack at speed, and that takes a very careful balance of lift and mass.

Thanks Xan, Thanks Mikki. You two crack me up. (and are they those white chocolate and macadamia nut cookies from Costco? I friggin love those things) Parachutes? Radial drogues did very well for me. Mount them close to where your COM will be when your fuel is just about all burnt off. That way you won't lose as much control (seems a common habit is to put them far back which can make you go all lawn dart on the tarmac if you're still airborne when they're deployed). Then, come in low, level, and hot. Drogues can survive up to about 550 m/s. But it's hard to keep a clean approach much over 300 IMO, so the radial standard chutes work fine, too. They actually lend quite a bit more drag. Try to be less than about 10 m over the strip when they deploy. It can get rather dicey.

So I took my fastest circumnavigator (it held the world record briefly, but was beaten by 2 seconds and a subsequent rule change has made the new record unassailable), swapped out the engines for whiplashes, stuck some lower drag flight surfaces on it and put this together: I could have sworn I saw it hit an even 1530.0, but the best I managed to screencap was 1529.7. And it has a few draggy parts that were necessary for the circumnavigation challenge but not this one, so I'll probably be back soon.

oh. well then in that case, there's this from another thread that was kind of an offshoot. top displayed surface speed in-flight was 1495.5. (other parts of that challenge were single engine, no non-cosmetic mods, a successful no-parts-lost landing, and speed taken from the F3 screen) Sometime tomorrow I'll see what I can do if I lift those restrictions and really unleash the beast.

What's the pressure?

check out the circumnavigation thread. A lot of us taking part in it have built jets that cruise at 1720-1740. That's a bit over mach 5. I've gotten my own over 1750 in a powerdive. Rapier in air mode, no oxidizer, low drag, high altitude. http://forum.kerbalspaceprogram.com/threads/126592-Kerbin-Circumnavigation-1-0-3-1-0-4-Aviator-Challenge-Continuation

I took the rule change regarding tail cones as impetus to turn my focus back toward distance rather than speed. My late 1.01 craft with 12 turbojets and 45000+ fuel capacity would have been capable of 5 or 6 laps but as fate would have it, pilot error claimed its maiden voyage and the beating drum of progress (version 1.02, released the following morning) would mean mean there would be no take two, as its capabilities were diminished to where 3 laps would have been a stretch. I never gave up on the dream. Sometime, I should put together a gallery of the cockamamie behemoths that have rolled out of my spaceplane hangar. Some actually flew pretty well. Many were an absolute handful. And most would explode in time acceleration. I had a really strong contender last weekend. Carrying about 25000 fuel, it was able to reach a cruising speed around 1530-1540 on 8 rapiers and complete full speed laps with about 3000-4000 fuel. But the sheer weight along with the inevitable mid-flight balance changes made climbing difficult, requiring 2-3 speed dives during ascent through some very lawn-dart-ish flight characteristics, meaning that reaching supercruise took 9000-12000 fuel, leaving me with just enough enough for 4 laps in most cases. So I looked back and I looked small. I took inspiration from the first plane I entered in this thread: Simplicity. NAmed for its design philosophy, it turned in a respectable 51 minute flight on a single turbojet. From it was born the Elaboration. I traded mk1 nosecone c-pit for a mk1 inline c-pit carrying a shock cone intake. The pre-cooler was swapped for a standard jet fuel fuselage, and an additional jet fuel fuselage section was added. The small gear were traded for a medium set on the hopes that the braking might be better. I took it out last night and fell about half a turn short. Realized I only need about 200 more fuel so a set of big s strakes along with a slight adjustment of the wing angle (aesthetics are important) and the addition of chutes and we have what I present below: 5 full circumnavigations in 3 hours, 43 minutes sharp (or +2 seconds if you want to count the time I was in shock and nearly having a coronary when she rolled.)

Rolls Royce, Boeing, Airbus, Lockheed-Martin, Northrop Grumman, Pratt&Whitney, and every other jet manufacturer also exploits physics. The jet's tail cone is often visible in high bypass turbofans like what you see on airliners but not always. In modern low bypass turbojets, there's usually some kind of thrust vectoring shroud that hides it. Also the purpose is to direct the engine's exhaust and increase the jet's exhaust speed (and thus thrust). The way we've been using them on rapiers is more akin to the boat tail of a precision rifle round in that it provides a clean collapse of the pressurized aerodynamic flow around the body to reduce drag as compared to a flat back, which would produce a choppy wake that reduces aerodynamic efficiency. The shock cone and various nose cones could be made of titanium like the real life tail cones of jet engines are and could be entirely capable of many hundreds or even thousands of hours of flight. Parachutes would likely not live happily for the few minutes it would take them to become cinderized.

No doubt that's a sub-40 capable craft.

I sent out an email to the staff to gather opinions. Jeb thought it was a wonderful idea, and wants it a deep candy red with pinstripes and ghost flames. Bill pointed out that it's painted precisely to prototype specifications, and that production color schemes will be dictated by the contracting agencies placing production orders. Gene diplomatically suggested that there might be highly proprietary technologies in place that would require an NDA to be signed before allowing any 3rd party contractors anywhere near it. (really, I think he just didn't want it moved off the Astronaut Center lawn. It's really close to his window, and provides a pleasant late afternoon shade) Finally, Werner quite emphatically insisted "NEIN NEIN NEIN! Ve have decadesh of verk in zis project und ve musht not let ze Soviets close ze procedural fairings gap!"

I'maderp oops. lol and to top it off I wasn't logged into imgur so I can't fix it. double derp lol. Is it Monday or something? (what? not till tomorrow? sigh)

Mikki- I *LOVE* that entry. I've done a whole bunch with crazy big jets and was ready to run a 5 lap run in 1.0.1. Finished a test run late one night, got home from work the next day, got patched to 1.0.2, and couldn't even make it to 3 laps. It was a 12 engine beast carrying over 44000 units of fuel but able to cruise at about 1640. Nothing I've tried in 1.0.2 with the 2.5m or shuttle parts has been all that viable so it really warms me over to see yours in action.

also, sorry about the rapid fire double submission. I didn't expect to be running a second one today but found the speed tests on that second one so encouraging I just couldn't stop myself. . But anyway, thanks for making and maintaining the thread. This challenge has been about 90% of what I've done in KSP for the last 6 weeks or so... Too much fun!