Heavy SSTO Efficiency Challenge

[KroShan]

This here doesn't take into account that more fuel also means more dry mass. But than Nerv gets even better.

Nefrum's Stingray Orange without payload:
30t (incl fuel for deorbit ~400m/s)
- 2x rapier, - Nerv, + dart:
24,3t (incl fuel for deorbit ~400m/s)
than added 72t payload and calculated the initial mass for different dV requirements with:

m_0 = m_1*e(dV/(v_u)

Spoiler

OXcost /unit	LFcost /unit	ISP Nerv v_u/9,81	ΔV	Nerv m_0	Nerv m_1	ΔM_Nerv	Nerv m_1/m_0	cost_Nerv	ISP Dart v_u/9,81	Dart m_0	Dart m_1	ΔM_Dart	Dart m_1/m_0	cost_Dart	cost-ratio
0,18	0,8	800	1	102,01	102,00	0,01	1,000	2,08	340	96,33	96,30	0,03	1,000	2,65	0,785
0,18	0,8	800	10	102,13	102,00	0,13	0,999	20,81	340	96,59	96,30	0,29	0,997	26,54	0,784
0,18	0,8	800	100	103,31	102,00	1,31	0,987	209,28	340	99,23	96,30	2,93	0,970	269,06	0,778
0,18	0,8	800	200	104,63	102,00	2,63	0,975	421,25	340	102,25	96,30	5,95	0,942	546,31	0,771
0,18	0,8	800	800	112,95	102,00	10,95	0,903	1751,36	340	122,40	96,30	26,10	0,787	2396,26	0,731
0,18	0,8	800	1000	115,86	102,00	13,86	0,880	2217,81	340	129,97	96,30	33,67	0,741	3090,65	0,718
0,18	0,8	800	2000	131,61	102,00	29,61	0,775	4737,01	340	175,40	96,30	79,10	0,549	7261,82	0,652

Here you can see that the burn is always more expensive with the dart.

[TaxiService]

>> WORK IN PROGRESS <<

Here's my first iteration of the heavy SSTO plane, Fire Spirit. I managed to get this baby into the 300x300km orbit with two orange tanks on the first flight attempt. (though I had to move some fuels around during the ascent)

Spoiler

I need to refine this SSTO design as there are 1420 LF and 444 OX left.

Mod: KER, Alarm clock, MM. 

Score: NOPE. Need to (1) cut down the fuel amounts; (2) land this plane on KSC; (3) find out if the design survives the reentry; and (4) figure out how to use RCS nodes for docking

 

Edited June 12, 2016 by TaxiService
Edits

[mk1980]

your craft doesn't seem to have a docking port. if that's the case, you should add one (it's one of the rules of the callenge)

also, i think it would make sense to keep the rapiers burning until you run out of oxidiser. hauling around unused oxidiser is a waste of deltaV, especially considering the low value of oxidiser for the score. and don't forget the reentry burn - that will also take some fuel.

[herbal space program]

8 hours ago, KroShan said:

This here doesn't take into account that more fuel also means more dry mass. But than Nerv gets even better.

Nefrum's Stingray Orange without payload:
30t (incl fuel for deorbit ~400m/s)
- 2x rapier, - Nerv, + dart:
24,3t (incl fuel for deorbit ~400m/s)
than added 72t payload and calculated the initial mass for different dV requirements with:

m_0 = m_1*e(dV/(v_u

Here you can see that the burn is always more expensive with the dart.

Now that makes sense to me. Just to be clear, the reason I think the Dart might be a better option vs. the Nerv is not because I thought the orbital burns would cost less with the Dart, but rather that I thought their modest additional cost with the Dart was less than the additional cost of schlepping the extra two tons of engine into orbit. That extra two tons will require an additional 20kN of thrust all the way to orbit just based on inertia, not to mention the horrid drag and airframe-unbalancing aspects of the nuke. Also, the Dart can provide the thrust of 3 nukes during the rocket-powered ascent stage, perhaps allowing you to drop a Rapier from the design. If there were farther to go than a 300km orbit, that would all certainly change, but in this marginal case I think the money move might be to go for light and aerodynamic rather than heavy, draggy, and efficient.

Edited June 12, 2016 by herbal space program

[icedown]

I've been off the grid at the lake this weekend and it looks like we have some excellent entries.

@KroShan  Beautiful craft and excellent run

@mk1980 Very good run as well.  I have no issue with KER or even MJ.  As long as the mod does not change the aerodynamics or engines from stock, it's allowed.   This is a challenge about efficiency, so use of autopilots and information systems that can improve this is certainly allowed. Your second one is more along the lines of what I tend to build. Very Nice.

@kcs123 Definitely a gate crasher but excellent heavy design none the less.  I am a huge fan of B9 myself. 

@Mikki Cargo does not have to be inside a bay but must be detachable and the craft must be able to return without the cargo. 

@Nefrums That is definitely an interesting design.  I would have never thought about that type of configuration.

OP will be updated with current leaders soon^*

 

[Mikki]

Made one: "Double Jumbo"
 

Dropbox:https://www.dropbox.com/s/66stc6wufnk1cm3/SSTO Double Jumbo.craft?dl=0

Result:
LF  (full):  13395     (-left): -       0 =  13395
OX (full):  10265     (-left): -   546 =    9719  
Score:
LF   13395 x 0.8   =  10716
OX    9719 x 0.18 =    1749.42
Sum:                         12465.42

Well, by far not so good like @Nefrums excellently kerbaled super SSTO but hey, it flies like a charm. The  Mk2 enginefuselages provide some cheaty extralift and the tailfin is very tiny but so far behind that it gives surprisingly good and lots of pitchauthority. Lands like a feather, okay, i didn`t hit the KSC... 

It flies with 12 Rapiers and two ... errm ... the other jetengine... can`t remember the name . It has one radiator on top and two solarpanels lateral. And Vernors all around.
     

All Stock, looks like Skylon, weird...

Edited June 13, 2016 by Mikki
math

[mk1980]

don't want to be the "party pooper", but does the "stingray" actually qualify? don't get me wrong - it's a very impressive design, but it doesn't seem to fulfil the "must have functional RCS and a usable docking port" requirement. i don't see any RCS thrusters or vernors on the screenshots.

[icedown]

4 minutes ago, mk1980 said:

don't want to be the "party pooper", but does the "stingray" actually qualify? don't get me wrong - it's a very impressive design, but it doesn't seem to fulfil the "must have functional RCS and a usable docking port" requirement. i don't see any RCS thrusters or vernors on the screenshots.

Docking port, yes, It does have 2, including one of the front of the cargo. While this setup is not what I would call traditional, it does meet the requirements of a station builder. However, it does not have RCS, Thank you for pointing that out.

[TaxiService]

I got the second iteration of my SSTO plane that can make to the 300x300km orbit and deorbit into the atmosphere. I changed the tail parts, replaced RSC parts, added two airbrakes and decreased the fuel volumes.

But I am still rubbish at the safe and controlled reentry to KSC.

Spoiler

I attached the last picture of showing dry CoM and CoL of the plane. Anyone can give me tips on the controlled reentry? I tried a few AoA strategies (AoA=10, AoA=15, S-shaped paths, full RCS pitch) but it always ends up in rolling over and falling towards ground.

Also, not only this plane has this reentry control problem but all of my other smaller skylon-style SSTO planes (payloads - 5 ton, 14 ton and 36 tons to 75x75km orbits) always flip during reentry. However, those three planes recover and land on the KSC runaway successfully when the atmosphere is dense enough to use flaps.

Edited June 13, 2016 by TaxiService
More details

[icedown]

Well, the first thing I see is that CoL should always be behind the CoG.  Second would be lack of adequate vertical stabilizers.  Need the big s rudders at the back.

[TaxiService]

16 minutes ago, icedown said:

Well, the first thing I see is that CoL should always be behind the CoG.  Second would be lack of adequate vertical stabilizers.  Need the big s rudders at the back.

It is my bedtime soon but I made few quick changes to my plane. Besides the too much distance between wet CoM and CoL, is it good enough for the reentry?

Spoiler

 

[icedown]

The question will be do you have enough pitch control on climb out, but It should reenter better

[Mikki]

Hey @icedown

I have updated my post in your cool challenge, made a little math for you .

[mk1980]

tried a new design, based on something i posted eralier, just a lot smaller (original design was built for heavier cargo)

worked surprsingly well, except for the reentry. aerodynamically unstable

should have moved the engines further forward...

not in the mood to continue right now. maybe tomorrow...

 

if i get it to work, it should score pretty good. not as good as Nefrum's stingray but almost in the same ballpark.  uses about 8000 LF & 3000 Ox.

 

i think i would fit well into the "station builder" category. unlike the mk3 cargo bay, that "open end" design allows for some fairly bulky cargo stuffed inside a fairing for aerodynamics. most station modules etc. mass a lot less then fuel, so if it can lift a double orange tank, it should be able to lift pretty much everything that fits inside a 2.5 meter fairing. in theory one might even replace the mk3-2.5m adapter with an mk3-3.75m adapter and use a 3.75m fairing for even bulkier cargo. might have to use longer landing gears for the ground clearance, though.

 

Edited June 13, 2016 by mk1980

[Nefrums]

9 hours ago, icedown said:

Docking port, yes, It does have 2, including one of the front of the cargo. While this setup is not what I would call traditional, it does meet the requirements of a station builder. However, it does not have RCS, Thank you for pointing that out.

It actually has a fully functional rcs system inside the service bay. It is visible in the pic where it drops of the tanks.   no fuel for it thou..

But I think it might disqualify itself by having a nosecone of the orange tanks and hence dropping of more parts then the two tanks.

 

Edited June 13, 2016 by Nefrums

[herbal space program]

4 hours ago, Nefrums said:

But I think it might disqualify itself by having a nosecone of the orange tanks and hence dropping of more parts then the two tanks.

I hope that this would not be a disqualification, as the cost of taking that extra mass into orbit as cargo far outweighs whatever pittance you might save by having slightly less mass to de-orbit. For my part, I was planning on putting the docking port on the front of the tank to be delivered, as if it were to be added to an orbital station. Could we get a ruling on that please OP?

[icedown]

4 hours ago, herbal space program said:

I hope that this would not be a disqualification, as the cost of taking that extra mass into orbit as cargo far outweighs whatever pittance you might save by having slightly less mass to de-orbit. For my part, I was planning on putting the docking port on the front of the tank to be delivered, as if it were to be added to an orbital station. Could we get a ruling on that please OP?

The design of this challenge is in the spirit of the K-Prize.  Rule 1 states that the craft must lose no parts except for the 2 tanks.  The loss of the usable docking port and non-functional RCS are also issues that add up to this being a gate crasher.  That being said, this is a VERY good design and I think with some very small modifications can regain it's position in the list.  The RCS does not have to be one of the monoprop ones. The Vernor engine does qualify for RCS and mp fuel does not have to be included.  It has to be functional but does not have to be used for this challenge.  I would like to see this take it's place in the proper list though.

 

@Mikki Since you did not land at KSC, I needed your landing coordinates for scoring.

Edited June 14, 2016 by icedown

[Nefrums]

Fully understandable, the ship was not designed for this challenge, just adapted a bit.  

 

[mk1980]

what about fairings? the "open end" craft i was playing around with also has a nosecone (on the back end of the tank) for aerodynamics. it would probably also work with no back end at all, but the blunt end will create lots of drag.

i guess i could just wrap the tank into a fairing, though. technically the craft doesn't lose parts when the base of the fairing is on the plane and not the cargo.

 

[herbal space program]

9 hours ago, icedown said:

The design of this challenge is in the spirit of the K-Prize.  Rule 1 states that the craft must lose no parts except for the 2 tanks.  The loss of the usable docking port and non-functional RCS are also issues that add up to this being a gate crasher.  That being said, this is a VERY good design and I think with some very small modifications can regain it's position in the list. 

Actually, I think that ruling  unfortunately may make this sort of design a non-starter.  If you can't do anything to make that big orange tank more aerodynamic at the ends, I think it will create so much drag that flying it to orbit outside of a cargo bay will get you nothing. I suppose one could leave only the back end naked and decouple it from a nose cone mounted at the front, but in my experience those naked back ends are almost as bad as naked front ones. It's a pity, I was maybe a couple of hours of tweaking away from being ready to submit my own entry.  I guess I had reasoned that there's really no sense in taking two jumbo tanks to orbit if you can't do anything with them when they get there, so I had the docking port on the front of the tank. The idea was you could dock it to whatever station you're building, then fly back to Kerbin to get the next one, but I guess that's a different challenge. Anyway, maybe I can come up with a way to have decouplers at both ends of the tanks in s manner that won't destroy the craft if they're both triggered at once....

Edited June 14, 2016 by herbal space program

[Mikki]

9 hours ago, icedown said:

Since you did not land at KSC, I needed your landing coordinates for scoring.

@icedown

Yupp, i know you want us to properly land at KSC, i`ve grounded actually at the westcoast of the KSC continent, where the nice little lakes are. No matter if you consider me disqualified, i am refurbishing my "Double Jumbo" and gonna do another valid entry soon! I think i can make a four digit score...

[Montag]

On 6/10/2016 at 8:27 AM, KroShan said:

Well - i didnt think i works out on my PC but 1.1. does wonders
THX for the Challange i wouldn't have tried it without- my biggest SSTO sofar was a design for a bit more than one orange tank.

I basically copied my design from Skylon - first i didn't want to, but in the end the high mass of the engine cluster forced me to put it near the Center of Mass for balanced empty flight.

 

Can you post and link to your craft file and can it return safely with empty orange tanks in the bay?

Edited June 14, 2016 by Montag
asked about return flight

[mk1980]

new attempt. after some redesign of my previous craft, i got it a bit more stable. still flies like a cow and i had to use like a dozen struts to make it not explode during takeoff.

and i found a clever (*cough*) solution to the nosecone problem. hope it qualifies. technically we decouple the nosecone, but only for a minute or so, then we dock it onto the (now free) docking port that previously held the fuel tank.

the docking was needlesssly complicated since i'm an idiot and put the engines so close together that the cone almost didn't fit through it. but that way at least the RCS ports were not entirely useless

 

LF: 8450 - 30.30 = 8419.7

Oxi: 3190

MP: 120 -101 = 19

score:

LF 8419.7 * 0.8 = 6735.76

Oxi 3190 * 0.18 = 574.2

MP: 19 * 1.2 = 22.8

sum: 7332.76

 

 

 

 

[g00bd0g]

@icedown

Just did a slightly modified version of my "most practical plane in KSP"  I ditched the MK3 command pod and added some fuel tanks. I will upload the video later, when I go to bed. I did have to F9 once because I forgot to transfer remaining fuel forward and lost control on re-entry. Not as good as a Nefrums or MK1980 designs, but pretty good for a Cargo Bay type ship.

@Nefrums Actually, I'd love to see what you could do with a Cargo Bay style ship

Also, I'm very curious what launch profiles people are using? I noticed most others are using more LF and less OX than I am. Maybe I need to stay in atmo longer? I'm trying accelerate hard with minimal climb until I am over 300kN thrust and then try to hit about 1450m/s speed and 220m/s climb before I switch to closed cycle. Feel free to critique my launch profile.

Here's the numbers.

Starting fuel - remaining fuel x score multiplier

LF 12305 - 339 x .8 = 9572
Ox 8305 - 147 x .18 = 1469
MP 80 - 57 x 1.2      = 28

Score = 11,069

New video uploading now...

 

Video of my standard heavy lifter to tide you over till I upload the new one.

 

 

Edited June 15, 2016 by g00bd0g

[mk1980]

to be honest my ascent profiles tend to be a little chaotic. depends a lot on the number of engines i put on the plane.

my first design used only 8 rapiers with a mass of ~240 tons, so it had fairly low TWR at takeoff. in that case, i stay in horizontal flight to pick up some more thrust and see if i can go supersonic before climbing. if that works, i fly horiztontal until ~ 400-450 m/s, then pull up to climb reasonably quickly into the higher layers of the atmosphere.

with a higher TWR (like my most recent addition - 12 rapier & ~180tons mass), i pull up immediately to avoid the extra drag in the low atmo.

once i get to higher altitudes, it gets chaotic.

sometimes i lower my ascent a lot to squeeze out more horizontal velocity. basically a horizontal "speedrun" somewhere between 15-20km. i push the plane to >1500 m/s and then pull up and try to get the projected AP to a decent altitude before i have to switch over to closed cycle.

in other attempts i also do a "speedrun" but don't pull up a lot and keep going in a shallow climb in rocket mode. in this case i actually reach orbital speeds and *almost* cicularize within the atmo (like AP at 40km, PE at 20km). adding more horiztontal speed at that point automatically raises the AP out of the atmo, but it will be somewhere on the other side of the planet so that profile involves a very long "coasting" phase through the upper atmo with phyiscs warp. i usually try to avoid that since it takes a lot of extra time for (probably) very little gain.

and sometimes i just climb at a somewhat constant angle and just switch over when the rapiers get too weak to provide useful acceleration. i think that profile is a bit wasteful because i often end up switching over at subpar horizontal speeds (1300 m/s or something). that profile is my preferred method for the somewhat overengineered craft i use in career, for the simple reason that it takes a lot less time and effort (gets to orbit almost as fast as a rocket). i don't think it is competitive if fuel efficiency matters, but IMO saving a few thousand extra funds isn't really worth spending a few extra minutes of real time (except for the purpose of a challenge where funds == score).

 

no matter what ascent i pick, i always have the feeling that i'm doing something wrong i guess it can't be completely wrong, though, otherwise my contraptions wouldn't end up with roughly the same fuel spent as the other craft that were presented (?)