What did you do in KSP1 today?

[Geonovast]

2 hours ago, RealKerbal3x said:

Damn.... No screenshots. I guess I pressed Shift-F1 slightly wrong (damn Windows hotkeys, whenever I press F1 it googles 'how to get help in windows 10.)

Remap your screenshot key!  My secondary screenshot key is my back mouse button.

[Atkara]

Not much so far today, except from a minor rework on the wings of my Mk2 line of SSTOs. There were changes in their flight characteristics, so I had to iron things out and do a re-entry test for the heaviest use of this airframe: carrying fuel into orbit.

Passed with flying colors -heck, it even handles better than before.

[Hotel26]

2 hours ago, RealKerbal3x said:

Concorde replica

I *heart* Concorde...

Would love to see some closer-up pictures of Konkorde, from different angles and, preferably, at slower speeds, and maybe one from quarter front on the landing flare...  Actually, on take-off climb-out just before gear retract would be easier for you (without losing the plane!) and look just as nice.

Thanks for the pics so far...

[Guest]

1 hour ago, Kronus_Aerospace said:

Well in general I try to make all of my SSTO'S as aerodynamically efficient as possible, and they never require particularly flat trajectories to reach such velocities, My SSTO'S usually have a thrust to weight of around .6, and are more likely to dip below that number than above it, although it is true that this does not apply to all SSTO'S, especially SSTO'S with drag issues as it is more efficient in that case to take slower but more steep flight Profile. I think 1200 m/s is rather low considering that is well below the maximum operating potential if the R.A.P.I.E.R.s, a fairer estimate in my opinion would be 1400-1500 m/s, having built innumerous interplanetary capable SSTOs I have done much experimentation with flight profiles and I find that those numbers work the best.

What kinds of payload volumes do you launch? 

I can easily make a 0.6 TWR / 1400-1500 m/s SSTO, but not if my payload is much wider than would fit in a cargo bay. 

There's a common misconception going around here that spaceplanes don't scale to wide cargo volumes. I believe a source of that misconception is (1) never even thinking outside the box (i.e., cargo bay), and (2) overengineering for aerodynamic efficiency. This pushes you into narrow, streamlined payloads even if you are outside the cargo bay, and significantly limits the usefulness of planes as lifters.

So relaxing the aerodynamic efficiency target a bit e.g. for a 0.75...0.85 initial TWR and 1200...1300 final jet-powered velocity will let you loft all manner of weird-shaped payloads, and you're still much more efficient than a rocket (as well as easy to fly).

(I am thinking though that for really heavy lifts and large volumes, VTO/HL spaceplanes just might combine the best of both worlds -- excellent aero efficiency and reliable 100% recoverability. I think I will be attempting that for my next heavy launch.) 

[KerikBalm]

1 hour ago, Ajiko said:

You are mistaken, 1450-1470 can be reached with Whiplashes easily, it depends from aerodinamics and flight profile.

I think it needed to reconsider some common beliefs about spaceplanes effectiveness.

Ummm, are you talking orbital or surface velocity? the whiplashes have a hard mach limit that is lower than the rapiers

Spoiler

Rapiers have an absolute maximum of mach 6, dropping quite steeply after mach 5.5 (their practical limit):       

 velCurve
        {
            key = 0 1 0 0.08333334
            key = 0.2 0.98 0.42074 0.42074
            key = 0.7 1.8 2.290406 2.290406
            key = 1.4 4.00 3.887193 3.887193
            key = 3.75 8.5 0 0
            key = 4.5 7.3 -2.831749 -2.831749
            key = 5.5 3 -5.260566 -5.260566
            key = 6 0 -0.02420209 0
        }

Whiplashes have a hard limit of mach 5.5, dropping quite steeply after mach 5 (their practical limit):

        velCurve
        {
            key = 0 1 0 0
            key = 0.2 0.98 0 0
            key = 0.72 1.716 2.433527 2.433527
            key = 1.36 3.2 1.986082 1.986082
            key = 2.15 4.9 1.452677 1.452677
            key = 3 5.8 0.0005786046 0.0005786046
            key = 4.5 3 -4.279616 -4.279616
            key = 5.5 0 -0.02420209 0
        }

0.5 mach faster equates to 10% faster (if baseline is mach 5). This translates to about a 150 m/s difference, if the designs are operating around 1,500 m/s

But its more than that as the rapiers can get closer to their speed limit, because they lose less thrust at higher altitudes

Spoiler

Whiplash atm curve:

            key = 0 0 0 0
            key = 0.045 0.166 4.304647 4.304647
            key = 0.16 0.5 0.5779132 0.5779132

Rapier atm curve:

            key = 0 0 0 0
            key = 0.018 0.09 7.914787 7.914787
            key = 0.08 0.3 1.051923 1.051923

 

At 4.5% sea level pressure, the Whiplash has a 0.166 thrust multiplier, so the thrust to drag ratio for a given speed is thus 3.69x higher at 0.045 atmospheres - somewhere between 15 to 20 km.

The rapier meanwhile at 1.8% atmospheres, still has a 0.09 thrust multiplier, so the thrust to drag ratio for a given speed is thus 5x higher at 0.018 atmospheres - somewhere between 20to 25km.

Its easier to visualize it on a plot (although, it would be better if the tangents were taken into account). From .18 atmospheres, the Rapier is already starting to retain more of its sea level thrust than the whiplash (velocity curves complicate this, to be sure, and the whiplash does start with higher thrust), 0.18 atmospheres is less than 10km

Quote

Payload mass - means nothing (I think, you understand why). Payload fraction - means nothing (deliver 30% payload fraction to orbit with start wet mass of 30t much more heavy, than even task on 300t-wet-mass-monster, at first because for 300t monster you can did proper engines configuration).

I agree mostly with payload mass means nothing... by itself, mostly. There are problems with scaling planes up, so large payloads are still meaningful even if payload fraction drops a bit.

As to your comments on Payload fraction... I'm sorry, can you rephrase that, I really can't understand what argument you are trying to make.

Quote

Next thing a bit heretical - "LKO dV" means nothing (at this point some peoples pull out their rotten eggs for me, I know).

I can mostly agree with that, although its very closely linked to payload fraction. A high payload fraction design can turn that payload into fuel mass, slap on some nukes, and from the rocket equation we've got simply ln(wet mass/dry mass)*9.81*Isp. Payload fraction easily becomes the wet/dry ratio of the craft in orbit. 

That said, I don't care much for "SSTO to anywhere" designs, and I prefer more efficient cargo spaceplanes that drop cargo in LKO. What is the point of lugging along the airbreathing engines, wings, and (now empty) tanks that you needed to get to LKO?

Quote

I think its better to use for spaceplanes more universal efficiency marker - ratio between LKO dV and craft fuel mass fraction ((LKO dV) / (craft fuel mass fraction)). It removes the difference in the graduation between cargo-sstos and passenger-sstos for example, for heavy-sstos and lightweight "birds".

Try to graduate your crafts by this indicator. Maybe you find something interesting?

Again... I'm missing your point...

Fuel mass fraction determines dV, they are related by the rocket equation. I don't understand why you care about this ratio. The ratio will drop to zero for any single stage as dV goes up. For a specified dV, the only thing that changes this ratio is the Isp of the engine that you use to generate that dV.

As for passenger SSTOs, I simply count the mass of the crew compartments as the payload.

Edit, just tested 2 identical stock designs, on stock kerbin, the only difference was that I changed the engine on one from a whiplash to a rapier.

Both simply sat on the runway pitched 5 degrees up, and had wings with some inclination. SAS was on hold heading, I activated the engine at full throttle and retracted gear, no other flight input. It was a simple single stack design with liquid fuel only, so it should go faster than a cargo SSTO, as it has no oxidizer or payload weighing it down.

Whiplash: reached 1,420 m/s surface velocity. By 25km it had

Rapier: reached 1,636 m/s surface velocity.

More importantly.... it reached 1,635 m/s at 23,500 meters in altitude. The whiplash reached its maximum speed at 17.5 km.

At 23,500 meters, the whiplash was only going 1,400 m/s (actually, 1,400.3, but whatever, I have screenshots if interested)

At 26km the whiplash was only going 1,380 m/s. The rapier was still going 1,628 m/s

At 30 km, the whiplash was only going 1350 m/s (engine had cut out around 26 km), the rapier was going 1605 m/s (engine had also cut out, but at around 28km)

Compare the speeds at 26km: 1628-1380 = 248 m/s The rapier was going significantly faster at 26km.

In these jet only designs, the rapier was delivering well over 200m/s more velocity at high altitude. That is quite an advantage, before you even consider that you'd also have to add rockets (and more nodes/frontal area/drag) to the whiplash design to turn it into a spaceplane.

Edited February 12, 2018 by KerikBalm

[kamphare]

I'm currently back from a long break! Finally started playing a fairly heavily (gameplay) modded career mode game that I always wanted to do. I've only used a couple utility + visual mods in the past, so it's very exciting stuff to get into. I've been doing early game contracts, typical temperature readings etc. And hit a wall when I realized I can't get as high as the required 17km - so I started adding rockets to my plane:

...It didn't end well. But I'll be back with more attempts tomorrow!

[MaxwellsDemon]

The second resident crew of the Nedjkhert station (Salyut-analogue) landed in their 'Isis' crew return vehicle after a record-breaking* 156-day mission.   Another Kerbal was rescued from a crater-clippingly-low Munar orbit, and then I spent some time retrofitting all my booster designs with VaporVents.

 

 

 

 

* in this campaign

[Atkara]

53 minutes ago, Brikoleur said:

There's a common misconception going around here that spaceplanes don't scale to wide cargo volumes. I believe a source of that misconception is (1) never even thinking outside the box (i.e., cargo bay), and (2) overengineering for aerodynamic efficiency. This pushes you into narrow, streamlined payloads even if you are outside the cargo bay, and significantly limits the usefulness of planes as lifters.

I wouldn't call it a misconception but a preconception instead. And while it has to do with the cargo bay, and people's tendency to hear about SSTO and immediately think STS/Buran, there's a very practical IRL reason behind it: the necessity of a support structure around the payload. Without it, it most likely fall on the tarmac, before the plane even has a chance to takeoff -or even worse, the risk of breaking the plane in half, if the payload is too heavy.

Now, as far as KSP goes, you can simply autostrut and get this over with. And don't get me wrong, I'm not against it at all. But I would be a lot happier, if (besides building the plane around the payload, which can be done anyway) I had a way of cutting the fairing where it touches the parts of the plane I plan to use as support structure and from there, drag struts to the payload.

The alternative, would be to pretend I just did that and live a happy Kerbaleer ever after -which I may do eventually.

As for aerodynamic efficiency (and if I have understood what you mean by that), what I've seen so far has shown me that SSTO doesn't always mean climbing like a bat right out of hell, from the moment you leave the runway. Under-using Whiplashes or Rapiers, in exchange for a high climb rate won't give you what it otherwise could. Let them breathe, let them reach their peak thrust, before it starts falling off. As far as Rapiers go, unless I see a peak thrust of >340kN, I'm not happy.

[Kebab Kerman]

10 hours ago, Kronus_Aerospace said:

Hope you don't have trypophobia!

NO. JUST... JUST STOP. THATS TOO MANY ENGINES.

 

Seriously though, are you lifting an entire house into orbit?

 

*Sudden realization*

Hmmmm....

[Guest]

10 minutes ago, Atkara said:

Now, as far as KSP goes, you can simply autostrut and get this over with. And don't get me wrong, I'm not against it at all. But I would be a lot happier, if (besides building the plane around the payload, which can be done anyway) I had a way of cutting the fairing where it touches the parts of the plane I plan to use as support structure and from there, drag struts to the payload.

Yeah more flexible fairings would be nice. 

I don't feel bad at all about doing stuff that wouldn't work IRL. Starting from a 600 km planet with a neutronium core kind of does that to me.

[Kebab Kerman]

4 minutes ago, Brikoleur said:

...neutronium core...

Wait, what?

[capi3101]

I don't necessarily want to break up the conversation y'all are having about SSTO design. I'll say that I've got a very successful series of spaceplanes - fourteen main designs now with variants on a couple of them - based solely on the RAPIER engine. I'm a FAR flier at this point, so I don't know how much advice I could offer that would be useful. As a rule though, when I build, I start with the paywad and assume a 15% paywad fraction to guess at the final mass of the plane at takeoff. From there I go with 17 tonnes per RAPIER, one brake per engine, one shock cone intake for as many as three engines. And then since I fly FAR and use Procedural Wings, I have a complicated set of formulas for figuring out wing design that uses the same proportions as the Shuttle orbiter. 1200 m/s at 20,000m in air-breathing mode is what I usually get; I plan for a 1.6 wet-to-dry ratio for after the plane becomes a rocket around 29,000m, which gives you about 1500 m/s of delta-V. You can actually make the calculations for how much fuel that turns out to be; I reverse the proportion - instead of 45% LF 55% LOX, I go with 45% LOX 55% LF. Fourteen useful spaceplane designs....

 

Now that's out of the way, on with the thing that I sometimes do on this thread more than once a month...

Friday began with a 25 kilometer rove over the Münar surface using the rover Indecision, which ferried engineer Dilnard Kerman from the Hojo Alpha outpost to the Piper Alpha refinery. Dilnard's arrival allowed refueling operations to re-commence at Mün following refinery engineer Gillie Kerman's departure for training at Duna and Ike, and fuel run was made for the Munport space station. A Tater Catcher 7 Light asteroid probe was launched to attempt an intercept of asteroid MGH-836; the probe has just left Kerbin's SOI and should affect an intersect in about fifteen days. Meanwhile, after 29 days in transit, the Spamcan 7 lander from the Minmusport space station arrived at Mün. Since I needed that Spamcan back at Minmus for engineer Suus Kerman and pilot Helming Kerman to go to the surface (no landers were available), the Spamcan stopped at Munport just long enough to refuel and then was sent on a trip back. Meanwhile, the second and third excursions of the crew of Laggin' Dragon docked at the Dunaport space station commenced. The second excursion returned on vapors, but enough fuel was deemed available to send the third and final excursion down, landing three Kerbals at the Enchova Central refinery on the surface. Among them was engineer Magster Kerman, who resumed her role as the refinery's engineer following training on Ike. Since the station's fuel level was critical, the docked Old Bessie 7a heavy fuel lander was dispatched to the Scan Queen refinery at Ike, and a spare Spamcan was also dispatched from Dunaport to the Ikeport space station. Dunaport's periapsis had slipped below 60k during its operational lifetime, and so a short burn was made to return it above that critical orbital altitude.

On Saturday, the third excursion returned to Dunaport. Laggin' Dragon was given as much fuel as was available at the space station, enough to fill her tanks up only to 88%, which was more that enough for her to head towards Ike. A final remaining Spamcan 7 lander got the remaining visiting Kerbals out, leaving scientist Kirmund Kerman behind to man the outpost. 

Spamcan 7 after departing Dunaport. Laggin' Dragon is visible immediately to the left of the station.

Both Laggin' Dragon and the Spamcan arrived safely at Ikeport before the say was out. Meanwhile, with things to do over Eve, I decided to try a direct warp-back of the Heighliner 7 warp ship MSV Fat Man from Duna to Kerbin, forgoing the normal orbital period over Kerbol and just using a series of "warpbacks" to slow the craft down to orbital velocity. I discovered that the process shortened the wait time from days to a matter of hours - Fat Man was in a 600 kilometer parking orbit over Kerbin before Laggin' Dragon arrived at Ikeport. With the ship's return, I latched a Bill Clinton 7b grabber probe to the side of Fat Man, warped the craft out to an Eve flyby and then returned to the parking orbit over Kerbin. I then proceeded to land the probe, thus fulfilling an Explore Eve contract point to return a craft from an Eve flyby...

Even managed to get the thing down reasonably close to the space center...

Only other thing that happened Saturday was the arrival of the Minmusport Spamcan at Kerbin, where a burn was made to return it to the minty moon. It should arrive in seven days. Nothing happened yesterday, so at this point I've got to get Dunaport refueled, land some Kerbals on Ike, get Fat Man back to Duna at some point and begin some more Eve ops. Fair amount going on.
 

Edited February 12, 2018 by capi3101

[Hotel26]

10 minutes ago, Brikoleur said:

I don't feel bad at all about doing stuff that wouldn't work IRL.

Hear, hear!

I know that some people relish the realism.  I doubt they'd really enjoy working at NASA or JPL, though.  Too much realism; too much tedium.  Not enough scope!, when you are a single cog in an organization.

KSP is a much smaller set of rules but with a rich enough problem/solution domain for creativity, innovation and triumph.  When I leave the "realism" of my day job, this kind of unfettered 'play' is what I want to come home to!!  And it's realistic enough to still be recognizable as an achievement and provide a great deal of euphoric satisfaction.

2c

Edited February 12, 2018 by Hotel26

[Kebab Kerman]

I build a massive plane at least 7 months ago. Have a look!

https://kerbalx.com/KebabKerman/TU-935

I don't have an image, unfortunately. Not really sure why it has two stages, but it must be for something because I haven't used it in a long time.

[Guest]

47 minutes ago, Kebab Kerman said:

Wait, what?

Kerbin has a radius of 600 km but a surface gravity of 1 g. Everything we interact with has more or less the density you would expect. Therefore, it is logical to conclude that it consists of a mantle of normal matter surrounding a neutronium core.

(It could also be a hollow sphere with a roughly Earth-mass black hole at the centre of course.)

[Kebab Kerman]

4 minutes ago, Brikoleur said:

Kerbin has a radius of 600 km but a surface gravity of 1 g. Everything we interact with has more or less the density you would expect. Therefore, it is logical to conclude that it consists of a mantle of normal matter surrounding a neutronium core.

(It could also be a hollow sphere with a roughly Earth-mass black hole at the centre of course.)

We need a planet mod that basically removes the stock Kerbin and makes the heightmap super-high, to the point where the radius has to be 1km, with a hole in the ocean that leads to the center. That would be amazing. So that we can put stuff down there. Come to think of it, why hasn't anybody done something like this with a planet pack yet!?

Edited February 12, 2018 by Kebab Kerman

[TeslaPenguin1]

Today the Kertimis mission actually made it into orbit around Kerbin!

[KerikBalm]

@Kebab KermanYou want a Mohole on Kerbin?

Anyway, after the SSTO discussion of preceeding pages, I decided to test my SSTOs that work with a 3x Kerbin (1.25x atmosphere, sqroot(3) rotation periods) with stock kerbin and stock atmosphere.

I included unused fuel mass as payload.

My smaller rapier only SSTO that had a payload fraction of 7% for my 3x config, obtained a 40% payload fraction for stock... that included a mk3 large cargobay and ramp (which are quite heavy compared to a fairing).

Then I tried the super heavy Rapier + LV-N SSTO that I manged to get to a 17% payload fraction (not including fairing mass). This got a 48.75% payload fraction for stock kerbin. 49.25% if you count the fairing.

Edited February 12, 2018 by KerikBalm

[Martian Emigrant]

Hey all.

I did it again.

I am NOT trying to break the game. It just breaks

I started a new caveman game and wanted to see if I could get in space on the very first mission. You can. I did.

What's with that?

You aren't supposed to see the KSC from that high at that stage of the game?

Jeb died on that one. The ship crashed a bit over 100m above the square hole.

So I tried and succeeded to make a survivable flight and got these.

What gives?

Is this new? I run 1.3 with only MecJeb. It's not even on the ship.

 

ME

 

Edited February 12, 2018 by Martian Emigrant

[Geonovast]

11 minutes ago, Martian Emigrant said:

What gives?

I dunno but that's awesome.

Sometimes the glitches are really the best part of this game.

[Kebab Kerman]

1 hour ago, KerikBalm said:

@Kebab KermanYou want a Mohole on Kerbin?

-snip-

Pretty much, exept deeper and underwater. Give submarines a purpose. And I can't do it myself because I have no idea how to do so. I did make a sandbox planet over 4,500,000,000 km in radius. It should have water, and it has Kerbin gravity. Might make another one out of a gas giant. It orbits 1,000,000,000km out, although I will extend it to 50,000,000,000. I'll get a screenshot when I can. It's atmosphere is also at least 150,000km thick, making it perfect for sandbox experiments. I will also fix the heightmap so it has deeper oceans. SUBMARINES ARE USEFUL!

 

Now if only I could get it to work...

[TeslaPenguin1]

I made a boat once. It used wings as the hull. As it went across the water, it took off and crashed back into the water.  

[KerikBalm]

20 minutes ago, Kebab Kerman said:

Pretty much, exept deeper and underwater. Give submarines a purpose. .... I will also fix the heightmap so it has deeper oceans. SUBMARINES ARE USEFUL!

Why would a hole make a sub useful, when oceans that cover 2/3rds of Kebin, >90% of Laythe, etc etc don't?

[rvilela]

- Landed "sucessfully" my first SSTO somewhere in a isolated island and got these thrust effects : )

[Delay]

Decided to change the crew on my Minmus Station again:

And while leaving Minmus' SOI to get back to Kerbin, I had this rare event happening:

And I also did minor course corrections on my interplanetary satellite going to Jool. The ~94m/s plane change was done easily using ion engines, but I already realized how weak solar panels become at larger distances.