SSTO Help

[AeroGav]

4 minutes ago, MisterKerman said:

Okay so I just whipped up something which is probably terrible and won't be worth legitimately biting into, but I didn't spend long or think too hard about it. this was like 20 minutes to make the concept for a shape for a plane that at the very least looks okay? (Empty cargo bay. I just wanted a basic shape.)

What are your guys' opinions on the shielded docking port for a nosecone?

It is quite a lot draggier than an intake or a proper nose cone,  so the "ideal" is to use a nose cone on front and some kind of inline clamp o tron further back,  but in practice the mk3 fuselage parts you have there (esp. cargo bay) will dwarf the drag produced by your nose cone.  Your arrangement is aesthetically pleasing and easier to dock with.

If you end up needing more liquid fuel, you can make some tailbooms out of big S strakes instead of the Big S fin (which holds no fuel) ... but i agree the  fin part looks better.

What do you have on the back end ?  Is that a mk3 engine mount or a mk3 to Kerbodyne adapter ?     You need to choose a low drag method of engine attachment.    The Kerbodyne adapter has one Kerbodyne sized attach node on the back which makes a lot of drag if something with a different sized attachment face is stuck to it - such as RAPIER engines.

Or,  if you used a mk3 engine mount (space shuttle lookalike),  you need to remember that this has a central 2.5m node as well as the three RAPIER size ones.   If this 2.5m attachment point is ignored,  or has something with a wrongly sized attachment face stuck on it, it too makes drag.

So, if you're using one of these,  put a 2.5m tricoupler on that middle node (you'll probably want to offset the other engines outward a bit to make room) and give yourself three more engines.   Like I said previously, I like the mix of panther and rapier.   Why tricoupler, and not bi or quad?   Well, the bi only has slightly less drag than the triple,  whilst the quad has nearly twice the drag, so it's kind of the sweet spot.
Example of a 6 engine config -

Spoiler

 

 

Or Simplest of all, you could just drop that mk3 mount for a mk3 to 2.5m adapter, then go straight to a 2.5m triple mount (can always stick more engines on the wings if you feel you need more).       Bear in mind this adds rocket fuel to the back end of your airplane,  which will make it tail heavy on takeoff and a potential lawn dart when empty.    So you will want a short mk3 rocket fuel fuselage in front of the cargo bay to balance that out - which might be too much fuel for a vessel this size..   but I suppose that's not a bad problem to have.

Above all else folks, remember,  this three way adapter,  with a 1.25m on the top and three 1.25m on the bottom, is incredibly draggy 

But this one,  with a 2.5m node at the top and three 1.25m on the bottom,  cleaves the air like a teflon dart

[AeroGav]

40 minutes ago, MisterKerman said:

Also that's seven Rapier engines on an engine plate in the rear. No calculation, just seeing how it fit. I was hoping to get away with no engines on the wings. I've placed small nosecones on the nodes and recessed them. From what I understand that used to reduce drag on them but I honestly have no idea if that's true any more...)

Ah thanks for the clarification, ignore the stuff about the Kerbodyne adapter then !

I'll refer back to my previous comment about putting engines on the shuttle mount,  the triple 2.5m adapter is best, that would give you six engine slots.

Seven rapiers is insane  and that's also 14 tons at the back end of the airplane,  you've got less than 4 tons up front (the cockpit) to balance all that,  most of your cargo bay will be in front of your CoM as a result so there will be a large change in CoM as you load/unload cargo.

My suggestion of a 6 engine setup with 3 Rapier 3 Panther is 9.6 tons at the back end,  a bit lighter though still tail heavy !

Perhaps the mk3 to 2.5m adapter (with a short rocket fuel tank in front of cargo bay) is looking best,  put 3 panthers on the back and hang a rapier off each wing, as far forward as possible..

[MisterKerman]

So balance is my main issue. Those suggestions sound simple enough. I have 2 options basically: The triple Panthers with wing mounted Rapiers, or try my luck with all engines (3 Rap + 3 Panth) mounted heavily on the rear and figure out some way to keep it's wet and dry weight balanced.

I'll leave this for now. I'll try to have something to show you guys worth showing next time I make a post.

It's tough that the game is so picky and inconsistent in some ways. It really takes experience to get all the kinks out of a design because so much of what causes engineering difficulties is either hidden or nonsensical. I'm legitimately surprised I wasn't told outright to throw that design in the trash HARD with how little effort it took to come up with.

[KerikBalm]

Its been a while since I took a shot at SSTO spaceplanes on stock Kerbin. I now play on 3x rescaled system with 1.25x rescaled atmosphere (Kerbin's SMA is 3x greater, its radius is 1800km instead of 600km, rotation periods are increased by sqrt(3), and the atmosphere tops out at 87.5km instead of 70km). Generally speaking, getting to Kerbin orbit in such a system is roughly equivalent to making a SSTO in stock that does a Jool flyby, with no more than 1000 m/ generated from LV-Ns, and of course no use of Ion engines.

3x SSTO requires minimizing drag even more because the "centrifugal force" is much less. Your wings need to make a lot more lift when airbreathers top out around 1600 m/s, and orbital velocity is 4,100 vs 2350 m/s. Also it means accelerating to past 3,000 m/s while still in significant atmosphere.  If one can SSTO under those conditions, SSTOing on stock kerbin is a breeze for such a craft.

Generally speaking, I don't bother with multiple engine types. If you have panther's they will be just dead weight past 800 m/s... but worse than that, they take up valuable nodes for Rapiers that could be used to push you to a higher airbreathing speed. This means more frontal area for the same amount of rapiers, which means more drag. Whiplashes aren't so bad in this case, but I still want to squeeze more airbreathing speed out of my craft. Also TWR in rocket mode is important (more so in a 3x game than in 1x, as you get much closer to orbital speed on airbreathing alone, and you don't have to fight to accelerate in the air at over 3,000 m/s).

While Rapiers suck as LFO engines, 305 Isp is bad, and their TWR is bad... the closed cycle is a "free bonus". I have had the most success with Rapiers as the only LFO engines (I also use some LV-Ns, but they aren't needed, and certainly aren't needed in stock- I have pure rapier designs for 3x SSTOs). LV-Ns can help for adding a lot more wiggle-room on the LF:O ratio, and you can pile on more LF so that you don't worry about using too much in airbreathing mode). Other LFO engines just add more mass, and more frontal area/drag. IMO, 35 Isp (340 of an aerospike or Rhino vs 305 of a rapier) or less (315 of a vector) isn't worth it for the amount of engines one must add to make a difference (more mass and drag), although I did have working designs using Rhinos, my rapier only designs (well rapier +very long LV-N burns to apoapsis) got better payload fractions. Stock is more forgiving for this, as you really only need 1 higher Isp engine (LF only designs with LV-Ns work... whereas on 3x, you need a lot of rocket thrust to accelerate from 1600 m/s to 3000 m/s so you can finally get your Apoapsis up high)

Drag is a big problem, but if you want to carry oversize payloads... you just have to deal with it sometimes.. as in this massive fairing (note that the craft still has 107 tons of fuel, not including the payload dry mass...). So I wouldn't worry soo much about a shock cone vs nose cone drag, or tri vs quad coupler.

Although I'm strongly in favor of the 2.5m quadcoupler over the tricoupler. You want to look at drag per engine of the entire stack, not just the last part in the stack. Even if a quad coupler has more than 4/3 the drag of a tricoupler, look at the drag of 4 entire stacks with tricouplers on the end, vs 3 stacks with quad couplers on the end.

Spoiler

on takeoff:

 

I like to have every engines behind every stack... minimuze frontal area, this means even behind payload fairings, as you see about. CoM often shifts back as fuel tanks in front of engines empty, so its good to place some engines farther forward, and some wings behind the engines (like T-tails). One little trick I use for large SSTOs is to have an engine segment behind the payload fairing, that comes forward and docks after the payload is released:

Spoiler

This makes maximum use of frontal area, and shifts the CoM forward as well

Its also been mentioned here to use incidence on your wings: very good advice.

Big-S wings were also recommended: good advice, and it also helps to keep part count down (something very important to me for large cargo SSTOs on 3x kerbin). Part count is the reason that I use the Mk3 liquid fuel fuselage in that design, otherwise I'd be loading up with long stacks of mk1LF fuel fuselages (1 mk3 long part hold as much fuel as 25 mk1 LF fuselages). A single battery and RTG should be enough for a large SSTO (the battery is needed to supplement the RTG on reentry, when SAS can consume a lot of power, before aerodynamic controls are effective, or if you want to have a high AoA for the purposes of adjusting your glide slope).

For smaller designs where part count is not a problem: Rapiers have a rear node, capping it with a small nose cone reduces drag (but it can occlude thrust when the engine gimbals, turn on angle snap, and shift it back "1 click", I don't consider this part clipping). My design above has 40 rapiers, so to do this would be increasing part count by 40 (and I try to keep it under 200, so that its under 300 with the payload)... so I don't do it.

If you're up for abusing the part offset tool a little, you can put one rapier behind another, and either clip them or offset them, so the thrust paths are clear, but they still count as inline for drag calculations. I consider this a bit cheaty... although  I started working on a 3x design that does this offset thing just to see how much better it will perform with half as many stacks for the same number of rapiers.

The 40 rapiers on that thing is enough to lift the craft off the ground and get it past mach 1, even if it weighs 1 kiloton (1000 tons), so that is about 1 rapier per 25 tons... although more typical takeoff weights are 800 tons... so I'd concur with the suggestions of @Aeroboi for 1 rapier per 20 tons (although I don't do the climb-dive-climb... I'm able to pass mach 1 just in a 10 degree climb... bumping it up to 25 tons, I do drop the cilmb rate to about 5 degrees to exceed mach 1).

I also have 40 wing sections, which each have 5 "lift units". So that's 200 units per 800-1000 tons, so 4-5 tons per lift units. This agrees with @Starhawk's suggestion.

So, 1 rapier per 20 tons (15 for easier flying, the margins for stock are so high that this isn't a problem), 4-5 tons per lift unit (3-4 for easier flying and takeoff, again stock margins are huge. Payload fractions can exceed 50%). Use some incidence, try to place engines closer to the CoM so that CoM doesn't shift so much when the fuel tanks empty.

[AeroGav]

1 hour ago, KerikBalm said:

Generally speaking, I don't bother with multiple engine types. If you have panther's they will be just dead weight past 800 m/s... but worse than that, they take up valuable nodes for Rapiers that could be used to push you to a higher airbreathing speed. This means more frontal area for the same amount of rapiers, which means more drag. Whiplashes aren't so bad in this case, but I still want to squeeze more airbreathing speed out of my craft. Also TWR in rocket mode is important (more so in a 3x game than in 1x, as you get much closer to orbital speed on airbreathing alone, and you don't have to fight to accelerate in the air at over 3,000 m/s).

Referring to this diagram again,  

I find that 1 rapier and 1 panther per 60 tons gives me 1350 m/s in level flight,  2 rapiers per 30 tons pushes that up to 1500 or perhaps a little bit more, but you can see from the way the thrust curve falls off, you're getting into diminishing returns.  Obviously if your flight profile is a continuous climb, rather than levelling off for a speedrun, i can understand why you'd want the extra twr at mach 3-5.  The downside is that you've got 4 tons of engine mass per 60 tons instead of 3.2,  and performance at low speed is still worse.    Personally,  I also just find this combo easier to fly,  since thrust doesn't fluctuate so much between OMG we're going to stall below 200m/s and the crazy banzai charge above mach 2.   Also,  designing for airbreathing top speeds over 1500 starts to make the thermal situation stressful.

I would have thought that if the all rapier approach is better, it's going to be more so at stock scale,  since getting another 200 m/s airbreathing reduces the close cycle delta v requirement by 25%.   Rescaled,  it's less significant.

As regards to building for rescaled system,  it's been a year since i experimented with it.   I can't remember the exact factor i used,   it brought kerbin up to 2/3 diameter of our planet Earth.    I  made a whiplash/nerv mk1 crew shuttle that just barely got to orbit,  so i modified it so that the Whiplash could be jettisoned on flameout (they are relatively cheap),  which rendered the whole thing considerably more idiot proof.          

Anyway you've gotten me interested in rescaled systems again,  i'm going to try building a 3.2x   orange tank lifter ... that's a challenge !

The close cycle burn is going to require a moderate TWR be maintained for a long time,  so i think i'll go with primarily NERV propulsion again.   However, since all the MK3 adapters come with compulsory oxidizer tankage,  you might as well make use of it through your RAPIERs.   Assuming a 0.4 to 1 TWR on NERV,   we're going to need 3.5 to 1 or better lift to drag ratio so that gravity losses don't kill us.   My normal approach to keep drag down is to spam Big S strakes and put cones on everything..    but since i need to keep part count down,  we'll see if that can still be done. 

[KerikBalm]

@AeroGav

Yes, there are diminishing returns, but its still double the thrust at higher altitudes. However, you'll note that they still have a thrust multiplier of about 4 at 1,600 m/s, and based on that graph of 2.0 at about 1,700 m/s. That's not insignificant.

Depending on my loadings, I get to 1550 to 1620 M/s airspeed/ surface velocity. Double the thrust lets me operate higher. Also (particularly on my rescale, which makes the atmosphere thinner relative to the radius of the planet, since the stock ratio is way out of whack), when climbing, there is a limited window of time to get to the point where thrust drops off due to speed vs dropping off due to the air getting too thin. As I'm just using stock aero, which is still quite soupy, the drag losses are pretty high. Pitching up to climb out of the soup causes a lot of drag, accelerating level in the soup creates a lot of drag. I still want a decent rate of climb when the rapiers cut off. I want to be going 1550-1600 m/s and climbing when I go closed cycle. If I climb faster, then I am fighting gravity more, and have less time to accelerate. I want that high altitude acceleration and climbing power. Also a more rapid climb help with the thermal problems that you mentioned.

To me, I've always found the high altitude performance most limiting for 3x SSTOs -granted, just getting them off the runway and not crashing into the sea can also be a challenge, but after that its high altitude performance that I care about. I want my airbreathing phase to put me on a high and fast trajectory. Atmospheric losses at high altitude in closed cycle are punishing in scaled up systems, that's where my SSTOs make or break it. I'd be willing to consider Whiplashes, but I really think Rapier only works best.

I forget what my craft's dry mass is, but with a ~110 ton payload, and a >200 ton plus dry mass, changing half the rapiers for panthers is only going to save 20 tons... and I think it would cripple high altitude performance. Even if the airbreathing performance were the same, the closed cycle acceleration is needed to get to keep the craft climbing higher into the atmosphere for most of the burn (until it starts getting closer to orbital velocity)... I don't think it would do well with half the closed cycle thrust. I basically tried that with my earlier Rhino designs, where 1 rhino is equivalent to more than the closed cycle thrust of 11 rapiers.

2 Rhinos still needed the rapiers to burn for quite a bit in closed cycle before they could be shut off.

I'm sticking with all Rapiers for now, and they work well. I think they also win the stock payload fraction challenges...

Edited January 30, 2019 by KerikBalm

[AeroGav]

6 minutes ago, KerikBalm said:

I'm sticking with all Rapiers for now, and they work well. I think they also win the stock payload fraction challenges..

I think i won the last stock payload fraction challenge with like 49.98%,  with a version of this thing (liquid fuel only).   I suspect the design tradeoffs for a primarily NERV design are quite different from a chemical one.   Chemical wins the delta V challenges though, because you can make a 200 ton SSTO with 1 NERV,   it  uses more fuel getting to orbit than the LF one,  but it will also have lower dry mass once there.  OFC,  you could then object saying this thing doesn't have usable TWR once the OX runs out, etc. 

The part count though ! ouch.

A marginally less ugly version of the above,  video of it lifting an orange tank.

What do i need to do to play with your settings ?  Do I use this now?   Just use default settings and play on planet earth ?

 

[KerikBalm]

"What do i need to do to play with your settings ?"

Sigma dimensions rescale mod: https://github.com/Sigma88/Sigma-Dimensions/releases/tag/v.0.10.1

(I actually didn't play 1.5, and just game back to 1.6, updated kopernicus, haven't updated Sigma dimensions... doesn't seem to need an update)

Which of course needs kopernicus.

Then in the config for sigma dimensions (settings.cfg), use this (bold where changed)

Spoiler

SigmaDimensions
{
    // Base Settings
    
    Resize = 3 // 1
    Rescale = 3 // 1
    Atmosphere = 1.25 // 1
    dayLengthMultiplier = 1.732050807569 //1
    
    
    // Advanced Settings
    
    landscape = 1
    geeASLmultiplier = 1
    
    resizeScatter = 1
    resizeBuildings = 0
    groundTiling = 1
    
    CustomSoISize = 0
    CustomRingSize = 0
    
    atmoASL = 1
    tempASL = 1
    atmoTopLayer = 1
    atmoVisualEffect = 1
    
    lightRange = 1
    
    scanAltitude = 1
}

 

(the day length multiplier is sqrt (3), ensures everything that was mutually tidally locked stays that way, such as Duna and Ike)

[KerikBalm]

Also, here's a video of one of my older 3x SSTOs, not the latest version (with more wing, less mk3 and mk2 parts), in the 3x game:

Some design features are there for part count reasons. The smaller strakes holding 100 LF are nice, but they really increase partcount.

[AeroGav]

@KerikBalmWell,  it took me about three hours to figure out how to  get the Kerbin rescale mod installed,  and about another three to make the maiden flight of this thing.  I  did not load any payload,  and also the oxidizer tanks are empty.    I  wasn't actually planning to go to orbit , rather just make sure it could break mach 1 and that i hadn't done anything particularly dumb with the staging.

2 Panthers. 3 RAPIERs, 8 NERVs.    With no cargo or oxidizer, but a full load of LF, it weighs 101 Tons.  Dry mass is 55 tons.  Its rather docile but the handles like a Donkey with OCD -  tell it to pitch up, pitch down or bank the wings it does its best to ignore you.

Spoiler

Max speed on three RAPIER.    It might have gone faster lower down,  but i couldn't get it to go down. Might be less skittish with some payload and oxidizer aboard.

After lighting the nukes and removing nose down pitch trim, it does a gentle zoom climb to 40km,  then starts into a shallow dive.   I was mighty relieved when it started climbing again, for good this time, because stuff was getting hot.

 

And there we are, in orbit with a little bit of fuel left.   Of course, there is no way something this size could bring an orange tank.  What's a realistic payload fraction for a RSS stock SSTO?  Not much I'm guessing.   If It can carry a science lab and hitchhiker module, i'm happy.

 

https://www.dropbox.com/s/wlhimqnrg5e6ng9/Bright Hawk.craft?dl=0

ag 1 - nose up trim (rather weak)

ag 2 - neutral trim

ag 3 - nose down trim (rather aggressive)

ag 4 - panther mode switch 

ag 5 - nukes, toggle

ag 7 - switch mode on centreline rapiers

ag 9 - switch mode on outboard rapiers

I really need to go through my prototypes and get them KerbalX ready.   Hopefully i'll fly this again some day..

[Laie]

18 hours ago, KerikBalm said:

If you have panther's they will be just dead weight past 800 m/s... but worse than that, they take up valuable nodes for Rapiers

Minor nitpick... it's been a while since I last built a large SSTO plane, but IIRC it was common that the Rapiers provided more than enough thrust once they got going, but getting underway sometimes was hard-ish. As in taking longer than I liked, or requiring me to go supersonic before I could climb at all, that kind of thing.

In those cases, a Panther, even a single one, made all the difference, was comparatively lightweight, and had the promise of perhaps being able to cruise a bit in dry mode on return (when the plane was empty).

[Hotel26]

On 1/30/2019 at 4:06 AM, MisterKerman said:

a 1-way plus a 4-way to make a 5-way, and then put those 5-ways on either side of the craft

I *heart* this idea!  Wow.  Very, very nice.

Particularly since the unavailability of a particular docking aid has forced me to learn how to dock using a method other than the "fire pole" method, and one that is very MP-efficient, so needs only the smallest corrections.

Also, like that it is so unobtrusive, particularly for e.g. spaceplanes.

[MisterKerman]

22 minutes ago, Hotel26 said:

I *heart* this idea!  Wow.  Very, very nice.

Particularly since the unavailability of a particular docking aid has forced me to learn how to dock using a method other than the "fire pole" method, and one that is very MP-efficient, so needs only the smallest corrections.

Also, like that it is so unobtrusive, particularly for e.g. spaceplanes.

I usually try to use angle snap as well and give them a little tug in with the "move" widget. That way the game places them in the exact same spot. You can adjust them toward or away from the center of the craft as much as you like without misaligning them. (Though on very small light craft it might not be line up perfectly with your Center of Mass with that method, so just be mindful of that.)

[MisterKerman]

Okay, so I got up this morning and tinkered a little with my shuttle. I might be okay for balance but probably not. it's still too early and much too optimistic to be entirely true, so we'll see.

Takeoff

 

Optimistic fuel margins upon arrival

 

Offloaded all rocket fuel mix with LF still in wings. Now it's much too ass-heavy.

 

Transfer LF to front tank. Seems okay?

 

Summary:

I might be alright as long as I find out where I need to perform re-entry to make a fairly precise landing not using any of my fuel. This configuration will need to be changed for commercial passenger flights, but from what I can tell it's possible this design will be alright if it has enough lift, which currently it probably doesn't even come close.

EDIT: Okay so I F'd up... after delivery it actually looks more like this...

 

So I'm once again totally screwed for now. Why is KSP so much harder than real life is?

Edited February 1, 2019 by MisterKerman

[AeroGav]

2 hours ago, MisterKerman said:

Okay, so I got up this morning and tinkered a little with my shuttle. I might be okay for balance but probably not. it's still too early and much too optimistic to be entirely true, so we'll see.

Takeoff
So I'm once again totally screwed for now. Why is KSP so much harder than real life is?

I urge you to install RCS build aid,  which shows a red ball (dry CoM)  in the SPH/VAB.  You can also check a box to have it ignore the weight of a specific fuel type (eg oxidizer).   Whilst you can achieve the same effect manually loading and unloading tanks like you are doing,  it is much more time consuming and easy to make a mistake.  I can only concentrate that hard on  a problem for a few minutes at a time before i need to rest and do something less demanding, so wasting effort on something that can be automated is something i try to avoid.

BTW I'm not seeing a tailplane or any canards, i don't know if you were planning to add them later,  but the elevons on the tips of the main wing are close to your centre of mass and will need to generate a lot of downforce (negative lift, costing drag to generate) to push the tail down and get the nose up.   That is why you want to install a proper pitch control surface, and disable pitch control on the roll surfaces (usually).   I also use the "limit authority" option a lot,  the largest deflection angles produce more drag than lift,  so it's usually worth upsizing to a larger surface if you find yourself needing that frequently.    Also,  out on the wingtips,  large deflection angles produce a lot of unwanted yaw/sideslip,  which is evil.   Finally, for the ascent to orbit,  i'm usually making quite small adjustments to minimise drag and loss of velocity.      You can always turn the controls up to 100% again for re-entry and landing.

RSC build aid is quite a simple mod to install, no reason not to get it.     Kerbal Wind Tunnel is also pretty easy, gives a performance envelope for the airplane.

CorrectCoL is staggeringly useful but a little more tricky  - you have to manually install a couple of dependencies.  Even so the time taken to get it installed quickly pays off because it drastically cuts down the number of test flights - you get a graph in the SPH showing the nose/up down tendencies of the airplane,  you will know whether it's flyable before you launch it the first time.     

That 3x scale SSTO I made in 3 hours is a complex ship,  but thanks to these tools,  it flew to orbit the second time i hit the launch button.    The first time ?  I realised i'd set the Panthers to Dry mode and had to action group set up to switch 'em.   also  I found that the action group to activate the nukes overlooked one engine pair,  so i reverted the flight 1 minute in.    Also,  i still get my staging wrong sometimes,  like when you try to take off and find out that your nervs are set to start before the jet engines..

 

 

[Xd the great]

For the record, ksp is easier than real life.

3 hours ago, MisterKerman said:

So I'm once again totally screwed for now. Why is KSP so much harder than real life is?

They scaled down stuff, so ssto are easier.

[steve_v]

2 minutes ago, Xd the great said:

For the record, ksp is easier than real life.

[MisterKerman]

I meant like... my life... and I was joking... Anyways!

I haven't had a chance to properly apply all the control surfaces or anything yet. I've just added a few of the most influential ones for a brutal reference while I had some free time. I might work on it later tonight as well, but my job is pretty taxing on me and I tend to just fall asleep after my shift. KSP is mostly for my days off.

I definitely want to salvage this design but still make it look cool. I really really hate canards so I'll avoid them as much as I can but it's obviously a very effective solution to authority problems so I'll have to wait and see. Obviously this is a fairly rough WIP so I'll continue to tweak it to the best of my ability. The main problem is lack of experience hauling cargo of significant mass using an SSTO. I've only ever brought passengers and small satellites into space and designing SSTOs was never one of my strong points.

EDIT: I guess I'll be less sloppy with what I reveal and try a little harder to actually have a semi functional prototype closer to something that isn't just a straight up mindblowingly sad. I know all the basics for designing aircraft, just not balancing such significant CoM-altering payloads. I'll come up with something more presentable for legitimate criticism soon. Thanks @AeroGav

Edited February 1, 2019 by MisterKerman

[Daveroski]

This is my usual crew transport work horse. It will take a crew to orbit or as far as Mimnus and back.

 

I saw your post and as I hadn't yet done so in 1.6, I had a go at the Orange tank to orbit craft.

This craft took the tank to orbit and landed again. Full picture series and flight/ship details available on request.

 

D.

 

[MisterKerman]

@Daveroski

That's the sort of thing I was hoping to avoid. I didn't want a million wings hanging off of the craft. I'm going for a certain look that might not be entirely possible.  I was going to rely on a delicate balancing act to avoid it and still not entirely sure it's not going to work yet.

I did a 15 hour shift yesterday so needless to say I never got around to messing around on KSP, unfortunately. But it's pretty obvious my craft lacks lift because every other craft that lifts a big orange tends to just be a big mass of wing parts and engines so numerous the payload is an insignificant and negligent portion of the ship's accumulative CoM, shifting nothing when offloaded either due to that fact, or the fact that it's essentially an egg nestled inside of a basket in regards to where lift is applied.

I'll probably spam wings on the back of my craft but the mass issue will continue to be difficult to manage without simply bringing up a whole lot of extra fuel to transfer around for ballast. I think that will work...

I really really like the design of your personnel SSTO. That exactly the sort of look I'm going for!

[GoatRider]

What mod are you using to make these big windows?

[MisterKerman]

2 hours ago, GoatRider said:

What mod are you using to make these big windows?

Do you mean the cutaway view to look at the interior of craft? That's stock.

Look at the face-cams of the Kerbals on board in the bottom right of the screen. To the left of those there are some options you can click. Some allow a way to view the Kerbals inside of your craft from the exterior.

[Daveroski]

6 hours ago, MisterKerman said:

@Daveroski

That's the sort of thing I was hoping to avoid. I didn't want a million wings hanging off of the craft. I'm going for a certain look that might not be entirely possible.  I was going to rely on a delicate balancing act to avoid it and still not entirely sure it's not going to work yet.

I did a 15 hour shift yesterday so needless to say I never got around to messing around on KSP, unfortunately. But it's pretty obvious my craft lacks lift because every other craft that lifts a big orange tends to just be a big mass of wing parts and engines so numerous the payload is an insignificant and negligent portion of the ship's accumulative CoM, shifting nothing when offloaded either due to that fact, or the fact that it's essentially an egg nestled inside of a basket in regards to where lift is applied.

I'll probably spam wings on the back of my craft but the mass issue will continue to be difficult to manage without simply bringing up a whole lot of extra fuel to transfer around for ballast. I think that will work...

I really really like the design of your personnel SSTO. That exactly the sort of look I'm going for!

I could have used less wing. It is possible to launch a rocket from the runway if you can get it's nose up.

Getting the payload to orbit is the easy bit.

Getting the craft to respond well to re-entry and then landing on the runway, that is in my humble opinion, more difficult.

[MisterKerman]

@Daveroski

That's okay. I found an aesthetically pleasing compromise for my engine weight situation. I'm going to shamelessly steal @eddiew 's Wing mounts. A little drag will be the cost but I can balance the fuel a lot better this way. I want to keep the Cargo bay for lifting other things even if just for now I'm using it as an inefficient tanker.

 

As a result I'll most likely switch the engine mount from a MK3->Kerbodyne adapter to a proper shuttle engine mount with less engines on it, relocating some to the wing MK2 (Or possibly 1.25m) wing mounts I plan to steal the design of.

This is the MK2 wing mount design I plan to steal from Eddie. He can keep his wings however... they upset my OCD greatly.

[MisterKerman]

Update: I'm getting closer, but this thing is still a mess...

This is the craft fully fueled. It takes off before the end of the runway.

I ran out of time so the CoM is too far back once offloaded. I'll need to shed weight in the rear, unfortunately. This is it's current engine arrangement.

At least it sort of looks cool...

This was my best run. Will require a lot more work and a possible wing redesign. I'm not so sure MK2 parts and specifically the heavy MK2 -> MK3 adapter I used were such a smart idea. I might have to sacrifice some aesthetics in order to make orbit.