Dao. 'Big Red'-Class SSTO.

[Rune]

So, the last serious cargo SSTO I did was the Nodachi. Though act to follow! That thing had gorgeous lines and awesome performance statistics. Can I do any better? Well, I can do the same thing with MkIII cargo bays, and 175 parts. Yeah, I call that progress:

It ended up stubby and waaaay smaller (is that a bad thing?), but really, this is one of the most useful SSTOs I've made. It handles great, takes off before the end of the runway, and is as light coming back to it as you would expect of a plane that shed 2/3rds of its mass without the CoM moving in the slightest. And you know, the compact shape is still kind of interesting, I especially like how the winglets came out, makes for a good-looking profile no matter the angle. Props to Mesklin for inspiring the "canard as part of a delta" control surface arrangement.

Performance-wise, it retains the Nodachi's 4 "Turbo-RAPIER" powerplant, and it even achieves slightly greater payload fractions (Max. payload is about 33% of GLOW, and empty weight another 33%, giving a mass ratio of 1.5 to orbit). Only now that the engines arebunched together on the back, the flameout is even less of a thing to worry about, you can perfectly well time your engine switches by waiting for the sparks of total cutoff to come out of the engines (remember, first you switch the RAPIERs to rocket mode at about 1,500m/s somewhere between 25-30kms, then later you cut the turbojets when you are reaching orbital velocity). Note in the album how the "performance proof" picture shows a rendezvous with a station at 100kms circular with all of 10m/s left in the tanks without tapping the payload's fuel, or much of the monopropellant. That's kind of the maximum performance, BTW

Aerodynamic handling depends a lot on how close to maximum payload you are. I mean, it will handle perfectly fine at maximum payload, of course, capable of locking on to 45º angles of attack without issues and taking off well before you reach the SPH (at about 70m/s); but when you go with lighter payloads (it will put up anything you can fit in the bay, BTW)... then it maneuvers like a freaking jet fighter! While gliding like a feather. Seriously, incredibly noob friendly for 25mT payloads and smaller. In case you didn't know, the standard red tank payload is about 36mT (slightly more because of all the docking ports). Oh, and note how the tank payload I provide is not secured by struts and instead does a double-dock when you load it: that means you can bring full red tanks down to a surface without them moving around like spaghetti and protruding form the bay.

Oh, and speaking of payloads, I took the liberty of coming up with one set myself: the Exploration Package. 25mT of go-where-you-please modular ship.

Basically, a can lander with 3.5km/s in its tanks and TWR >0.90, and a nuke transfer stage that will give said lander another 3km/s without tapping its fuel at a decent 0.25 TWR. Do you guys like? It should look like this in space, though it's mostly untested other than fuel flow (it is simple enough that I feel confident it'll work, though). Duna-class missions should be a breeze, and I bet this could visit a lot of other places, Eelo included, if you know your navigation stuff. Maybe even Laythe, though I am not sure 3.5km/s is enough to make the ascent there after falling on chutes. Certainly any other sane place (No, Eve, I'm not talking about landing on you and ever coming back).

And just in case you manage to screw things up still (we all do), or for roleplaying purposes (and really, mostly because I was two parts shy of a round 175), I added and escape system (decoupler and chute) that ended up prettyfying the cockpit-hull interface. Check the last pics (or even better, the craft file) to see exactly how that looks, and remember to check the action groups before flying to see how everything works! I don't think I took the time to write a proper description in the file.

IMGUR ALBUM:

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DOWNLOAD:

Dao + Big Red fuel tank

Dao + Exploration Payload

IMPORTANT NOTE: As B.O.B. has kindly pointed out, due to the clipping to get the turbojets/RAPIER combo they can overheat and explode if both are blasting at full throttle with the RAPIERs on rocket mode. Do drop the throttle a notch when you get high, and sorry for failing to notice. I fear with the complicated mess the engine assembly and fuel routing system is, some clipping bug crept in, but since it is minor I don't think I will try hunting it down.

Rune. Ok, the Big Red situation is solved now, I can finally say I can manage MkIII parts without issues in public!

Edited January 7, 2015 by Rune

[Yukon0009]

another wonderful craft, Rune! duly +repped.

[GusTurbo]

I always get excited when I see a new Rune thread. Looks fantastic.

[Majorjim!]

Hi Rune,

I really like the rear end of the craft and the modular payload is cool too! Taking a 'big red' up in an SSTO is no small potatoes.

MJ

[Guest]

Very nice!

[Rune]

another wonderful craft, Rune! duly +repped.

Thanks!

I always get excited when I see a new Rune thread. Looks fantastic.

No pressure, right? I know I now check twice or thrice before uploading a file, and more and more of them end up in the bin of not-good-enough... Am I backing myself into a corner here? Nah, just a bigger challenge!

Hi Rune,

I really like the rear end of the craft and the modular payload is cool too! Taking a 'big red' up in an SSTO is no small potatoes.

MJ

Yup, the 'Big Red' is the gold standard of SSTO cargo: from that point onwards, you can run 90% of your space program on the back of your SSTO (which is great for career these days, after you unlock the tech the funds just rain on you with 100% recovery), and going any bigger is just for bragging rights and increasingly slow gameplay due to lag. Consider yourself challenged, sir, now that you dabble in spaceplanes!

Very nice!

Thanks! Even a short comment is always welcome. I encourage you to try it out, this one came out very easy and fun to fly!

Rune. Four comments, three rep messages. I think this one came out right.

Edited January 7, 2015 by Rune

[inigma]

Nice job Rune. Simple enough to inspire me to develop my own orange tank lifter SSTO spaceplane... hmmm

[Teefy]

i love this ship and i feel terrible for asking (well not really ) but can you possibly provide us with a detailed flightplan?

[Guest]

Even a short comment is always welcome.

I didn´t exactly know what to say about this incredible thing, but I didn´t want to leave you without a comment.

[Teefy]

i love this ship and i feel terrible for asking (well not really ) but can you possibly provide us with a detailed flightplan?

on a side note: i got it into orbit on my first try although i burned all the fuel of the science lab. my first ever ssto with jet engines i managed to orbit.

i cant overstate how much this ship rocks. <3

[Frank_G]

I love the combination of the Mk. 1-3 Pod and the new adapter tanks! Very nice craft.

I found, pulling the shielded docking port a bit into the capsule gives you a much more pleasing look. It is awesome how elegant and cleaned up KSP craft can look now with the new translation tools. No more z-fighting of to narrow attached parts and so... simply awesome.

[Rune]

i love this ship and i feel terrible for asking (well not really ) but can you possibly provide us with a detailed flightplan?

Sure! It goes as follows, with all the detail I can manage:

1- Press 'T' for SAS, 'Z' for full throttle, put

in the playlist, and hit '1' and '2' to get the engines roaring.

2- When you are at about 70 m/s, pull back as hard as you want, tailstrike is not a thing that can happen. Continue until your heading is 45º.

3- Listen to the music. Go get coffee, browse the web a bit. This part takes about five minutes with no player input.

4- At about 20,000m, start paying attention to your vertical speed indicator (next to the altimeter on a stock install, but a clearer one is the main reason I use KER). Don't let it go much over 100m/s, and remember the stock one is logarithmic: 'only a bit' to the right of 100m/s can perfectly be 180m/s.

5- Start dropping the nose as appropriate so you bring vertical velocity under 50m/s at about 25kms. No need to completely level off. I find I stay at about 20º over the horizon to do this part, but YMMV depending on how fast you got to this altitude. This is the part were you should get to almost or above 1,500m/s (surface) before the first flameout, and after some practice you also want to let your vertical velocity rise slowly so you get to the end of this stage moving quickly upwards. The faster you can make it here, the better, but once you start seeing sparks on the lower right engine and control becomes weird, you should press '3' to switch the RAPIERs to closed cycle.

6- If you waited till control was hard (greedy!), control will immediately return once you switch the RAPIERS. Keep at a 20º angle thrusting at full throttle and watch you vertical velocity rise. It is important that it rises quickly, having it over 100m/s at this point greatly diminishes aerodynamic drag and saves rocket fuel. At about 30kms and with the indicator either at 1800-1900 (surface) or ~2000 (orbit), you will get the second flameout. It is even more benign that the first, since airbreathing thrust at this point is only a small fraciton of the total. The main thing about catching it quickly is that you can save on drag by closing intakes with the action group '0', and save a few drops of fuel by cutting the non-functioning turbojets with '2'. Note: as B.O.B. points out in the very next post, I failed to find out over the five or so test flights that if you don't drop throttle a tiny bit the RAPIERs can overheat in this mode if they are working together with the turbojets. Sorry!

7- As you can imagine, form there it is a short push to the desired orbital altitude (I usually shoot for 75kms so drag takes it to the bare minimum, high efficiency 70kms circular). Circularize at apoapsis, deploy solar panels, from now on you have all the time in the world to remember to do things and take pictures. Hope you had a great flight!

You will note that the vertical velocity method I describe here is basically applicable to any SSTO. The only design-related variables are the altitude at which you start the speed run, and the maximum velocity on airbreathers you design can handle, adn those are kind of fixed once you pick an intake-to-jet ratio and maybe vary a tiny bit with TWR (hint: I always use the same ratio, so all my SSTOs fly mostly the same). This just adds the extra twist of switching half my powerplants to rocket power while still using the others for a little (not so little, actually, saves me hundreds of m/s in rocket delta v) extra push, and no crazy flameout spins of death.

Also, you will notice that I was putting stupid obvious stuff in there to get to a decent number of points: this is dirt simple, and can be summed up as: get quick to 25kms in altitude and do the speed run there, and the order of action group usage is '1','2', then '3' (at flameout), and then optionally '0' and '1' (at second flameout). But I wanted to put it with a bit of flourish

Rune. The 'no crazy spins of death' part I think you guys will like.

Edited January 7, 2015 by Rune

[B.O.B.]

Just did a test flight...

Nice performace and really impressive handling for something that big

But should come with a warning for dummies like me: "Will overheat and explode if you fail to realize R.A.P.I.E.R.s are set to automatic switching mode."

[Rune]

Just did a test flight...

Nice performace and really impressive handling for something that big

But should come with a warning for dummies like me: "Will overheat and explode if you fail to realize R.A.P.I.E.R.s are set to automatic switching mode."

Oh crap I totally forgot that! And it deserves a notice! See, I am on the 'extremely greedy' camp that actually trhottle down a bit to get extra oomph for a little while. So I haven't actually encountered the problem. But once you brought it up I remembered that in one flight I saw them climb a bit higher than usual after fiddling with the rear engine assembly to get rid of some unwanted engine torque, then totally forgot about the issue. Will post a notice right away!

Edit: Wait, you actually made it all the way until the RAPIERs auto-switched to closed cycle? Did you know you were flying on three jets there for a good while? Wow, this is actually a testament to the stability, I never pushed it that far.

I love the combination of the Mk. 1-3 Pod and the new adapter tanks! Very nice craft.

I found, pulling the shielded docking port a bit into the capsule gives you a much more pleasing look. It is awesome how elegant and cleaned up KSP craft can look now with the new translation tools. No more z-fighting of to narrow attached parts and so... simply awesome.

Thanks! It is a shame I took almost all the pics before coming up with that sinked decoupler as both the escape system and a very smooth finish between the cockpit and the crew module. I will try and update them as I fly this in my save. And I will also look into tthe docking port thing you mention... I move it around a lot since I usually build the payloads there, nice and clear, but it may be worth fiddling around with it afterwards.

Rune. See? I should triple-check.

Edited January 7, 2015 by Rune

[Exothermos]

Ah, darnit. This thing just shows me how overbuilt my latest efforts are. Super Nice!

[Starwhip]

Sneaky, having double wings like that. Mine are gigantic instead of 2-layered. Any performance gained or lost from that configuration?

(Also, maybe a flight plan and action group documentation on the OP?)

EDIT:

Ah, wait, there's a post up above with the info.