A new recruit takes to the skies

[Fraktal]

After several years of watching Scott Manley videos, I discovered to my great joy last week that the laptop I brought in November to replace my elderly eight year old previous one is capable of running KSP, so I grabbed it off Steam on the spot.

With one week's worth of experience under my belt, I decided to perhaps get acquainted with the rest of the community. The majority of the week I spent experimenting with Mk1 cockpits in particular, despite having read on these very forums that they make terrible spacecraft due to their low heat tolerance (which I found to be a bit exaggerated: they survive my usual 30° reentries just fine); barely an hour ago, I finally finalized a powered skimmer design that can make it from orbit to the ground 100% intact. It's not supposed to fly long distances, just aerobreak and go into a controlled glide towards level terrain for a smooth landing. Even the 909 on it is only to extend the glide range - and extend it does: in my latest experiment, I came down from reentry just off the western coast of the KSC's continent, flew over 2/3 of the continent at subsonic until the 909 ran out of fuel, then went into an unpowered glide and finally landed just over 20 klicks from the KSC with no damage (aside from the 909 blowing up because the aft ground clearance was too small). I'd prefer using a jet for this but of course, those can't take rear attachments...

Still having some difficulties getting it up into the air (veers off on runway despite being perfectly symmetrical, rocket flips over from excessively high CoL unless I stuff the whole skimmer into a fairing as wide as the rest of the rocket) but once it's up, it handles fairly well aside from the fact that the nose refuses to go anywhere beyond 20°-30° from prograde. Next are some variants (extended range, multi-cockpit, high-RCS tug, possibly a science variant too), then I'll start throwing in Mk2 fuselage for further experimentation.

So... yeah. I take to this game like fish to water. Probably because I'm a software developer by profession and KSP's try-it-doesn't-work-tweak-it-doesn't-work-tweak-more kind of trial-and-error experimentation is my kind of fun to begin with. Or maybe it's the customization. Either way, I love it.

I have a long-term project for building a reusable interplanetary ship, but I'll cut my teeth on building smaller stuff (and setting up relay sats system-wide) first because the part count of Project Argus will be high. Not reentry-capable and certainly not takeoff-capable (even if it weren't too heavy, that kind of load on the physics engine would be kraken bait, I think); more like a mothership for three SSTOs (two rocket-powered, one rocket/jet hybrid) and a parasite rig for low-grav ISRU. But again, that's a project for another day.

[monstah]

One week, and the project is already reusable interplanetary ship? I'd welcome you, but it feels like you've been with us for a while and simply haven't realized it!

[Fraktal]

No, I really did start KSP last weekend. It's just that I went "waaaaait a second, I can use docking clamps for more than just building stations" and started wondering: if a big ship needs refueling, should I just bring the fuel or should I bring the fuel tank too? That is, should the fuel tanks be fixed, or should they connect with docking clamps so that the hauler bringing the fuel can replace them on the fly or even daisy-chain them for arbitrarily increasing range? And if the tanks can be daisy-chained, why not make the engine blocks daisy-chained too to keep the thrust scalable alongside the extra fuel weight?

[monstah]

19 hours ago, Fraktal said:

why not

Heh, in my case, CPU. But, yes, my first stations were daisy-chained tankers with docking ports in a 3-symmetry that looked so awesome and sci-fi, but totally killed my computer

[Fraktal]

As of right now, I'm continuing my experiments with Mk1 cockpits. In my latest line of experiments, I attached a Juno to see whether I can go for full powered flight after reentry. It's working alright and I managed to pull off two landings on the KSC runway without breaking anything.

Then I started experimenting with replicating the design with as low-tech parts as possible. Thing is, this produced the following:

A pair of wings placed with mirror symmetry and thus should be perfectly identical... and yet one produces orders of magnitude more lift than the other at any non-zero angle of attack, regardless of SAS. SAS can keep it under control, but the thing needs to go at transsonic speeds just to maintain level flight without me having to keep pressing the S key because tier 4-5 wings suck when it comes to actually making stuff fly.

Edited February 4, 2018 by Fraktal

[Kernel Kraken]

Welcome to KSP, Fraktal! This is some seriously impressive stuff; I'm on my 250'th hour and only just got to being able to orbit consistently. That's still up for debate wether I can do that. Good job!

[Fraktal]

I've recently started experimenting with Mk2 hulls and came up with a dual-Panther design that has trouble even breaking the sound barrier during normal flight, but can hit Mach 2.07 without afterburners if I keep prodding the SAS override every now and then to keep the nose perfectly level (and I mean perfectly: 3 degrees up and it starts losing speed). Even if I drop all the oxidizer (I slapped on a 909 so that it can deorbit itself from LKO without an extra stage) and gain about 0.2 TWR, it only buys me about 0.03 Mach before it can't go any faster without being knife-edge horizontal.

If SAS isn't off, the thing wants to nose down so SAS keeps every pitch-enabled control surface trimmed up all the time, which causes considerable drag. Adding on canards counteracted this somewhat, but it still isn't enough and I can't add any more without going unstable (it's already doing Pugachevs whenever I try to turn, with or without reaction wheels). Funny thing is, according to the aero debug data, the one part causing the most drag by far is the second rearmost part of the main body (Mk2 LF tank), which should be shielded from the airflow by the part in front of it (Mk2 cargo bay attached upside down so that it can quickly ditch the contents mid-flight in an emergency without having to roll upside down and pray that the stuff doesn't crash into the tail).

Edited February 13, 2018 by Fraktal

[James Kerman]

Welcome to the forum, @Fraktal.

I'm not a space-plane guy but I have read that the Mk2 Bicoupler is one of the draggiest parts in the game and the Mk2 parts are generally more difficult to work with.  Luckily @AeroGav is one of the masters and has created a tutorial on the Mk2 parts:

 

[Fraktal]

Nice. Angling the main wings up 1° for my latest test flight did the trick:

• Takeoff, gears retract, SAS fixed to horizontal at ~200 altitude. Face east, full throttle in dry mode.
• Accelerates uninterrupted all the way to Mach 2.12.
• 100 kilometers east of the KSC, I throttle down and turn around. Speed drops to Mach 0.3. Face west, full throttle.
• Cannot break past the transsonic shock at 8+ km altitude, still only at Mach 1.07 at KSC flyby.
• Altitude drops below 3.5 km behind the KSC, speed begins sharply increasing. Plane misses the mountains by less than 700 meters (and would've crashed without the extra lift from the acceleration), already at Mach 1.86 at altitude 6153 by the time it reaches the foothills on the other side. Speed still keeps climbing despite flying at 5° pitch.
• Mach 2 at 7339 altitude, at 7° pitch.
• Speed stops increasing at Mach 2.02. I level out with SAS override, speed climbs up to 2.12 then starts dropping.

So my observation is that the fuselage is fine as it is, but the engines are air-starved. They're already flaming out on the runway if I increase throttle too fast because the dual radial adjustable ramp intakes barely work at a standstill, but high-speed movement is fine.

[Grizzlitn]

Welcome and good luck with your project me too I am new but I have some problem with my PC so I can't plane KSP correctly now

[Fraktal]

So, I swapped out the radial intake with a pair of circular ones, no decrease in speed whatsoever and the Panthers stopped flaming out on the runway. I'm keeping them, then.

Then I decided to have a little fun, replaced the Panthers with ramjets... and promptly dropped my jaw as the sucker went suborbital with a 120 km apoapse at a 10° angle of ascent!  Didn't have enough vacuum delta-V to circularize and had some trouble with reentry because I ran out of power without any engines running and consequently couldn't keep the nose up and almost fried Jebediah, but still!

[MrChumley]

On 2/12/2018 at 6:11 PM, Fraktal said:

I've recently started experimenting with Mk2 hulls and came up with a dual-Panther design that has trouble even breaking the sound barrier during normal flight, but can hit Mach 2.07 without afterburners if I keep prodding the SAS override every now and then to keep the nose perfectly level (and I mean perfectly: 3 degrees up and it starts losing speed).

Welcome to the forums!  At this rate you should have an SSTO in no time!

Protip (that might help): (mod key) + A,W,S,D  will set trim.  (mod key) + x resets trim.  The (mod key) is different depending on what operating system you are using

• Windows: ⎇ Alt (e. g. ⎇ Alt+L)
• Mac OS: ⌥ Option (e. g. ⌥ Opt+L)
• Linux: KSP 1.1+: Right-Shift (e. g. Right-Shift+L) Don't confuse this with Left-Shift, which will fire your engines! KSP 1.0.5 and earlier uses a different key, which can cause issues in some window managers when playing in windowed mode.

I hope that helps a bit. 

Thanks for popping in!  It's always good to have another Space-plane engineer around

[Fraktal]

I...

...I did it. 

I reached orbit with an SSTO. 




Used up more fuel than absolutely necessary because I hadn't realized my apoapse and periapse had switched and kept burning to raise the latter, unaware that I was burning away from it now.

[Kernel Kraken]

I can't even orbit properly. I would rep but I'm out of likes

[Fraktal]

For that matter, I have since begun experimenting with Rapiers.

...meh. Airbreathing performance is awesome but I don't like the fuel usage in closed cycle. I think I'll stay with the ramjet-nuke combo. If it ain't broke, don't fix it.

Also, I discovered that Mk3 hulls carry enough fuel for me to use afterburning Panthers as regular engines. Four Panthers with the burners always on propelled my first Mk3 with something, like 45 minutes of supersonic flight endurance. Tried attaching 8 using stacked bicouplers, but it was too heavy for the wings.

Also also, I just hit an important milestone in my KSP adventures: I accidentally killed Jebediah with a physics glitch.  Namely, I just flagged the Crater Rim DSN station and was running down a rather sheer slope under 4x time acceleration when Jeb, who was stumbling the whole way due to the time acceleration, stumbled so bad he started literally rolling down the cliff, glitched into the ground, stretched out upwards and went POOF.

[Fraktal]

After a week of hiatus to regain my muse, I started experimenting with a Mk1 SSTO design. Three ramjets, four nukes, can pull off a round trip to Minmus including a landing, but I really have to squeeze out every last bit of delta-V.

Short summary of the latest test flight:

• Takeoff, ascent at 15° angle (at 20°+, the ramjets can't even break the sound barrier) until ramjet thrust fell below 250, then switched over to the nukes and eventually managed to very barely pull the nose up to 45°.
• Circularized just above 120 km. Approximately 2100 m/s dV remaining.
• Direct flight to Minmus, arrived with 937 m/s dV remaining. Tried a Mun gravity assist in a previous test flight, but that plane spontaneously detonated in the middle of the slingshot while I was on the map screen setting up a Minmus insertion maneuver node. The flight log was completely empty, no part destruction or pilot death reports. Just a split-second explosion noise and instant catastrophic failure, Jeb KIA.
• Landed on a 23.3° slope on Minmus, 567 m/s dV left.
• Takeoff and escape burn back to Kerbin with a 60 km periapsis. 49 m/s dV left.
• About 4-5 days and a dozen aerobreaks later, safely reentered 32 days after departure. Burned the remaining fuel with the ramjets at low throttle to reduce weight as much as possible.
• Despite parachutes slowing descent to 9.4 m/s, plane splashed down cockpit-first and broke up into a dozen pieces. Valentina KIA and I'm editing the save file because judging from the fact that Jeb hasn't respawned after a month, the "respawn missing pilots" doesn't seem to apply to KIA ones.