Smallest SSTO with orange tank payload [STOCK 1.0.5]

[Kergarin]

Updated rankings 

@Nefrums: congratulations for being the first master and still lowest part count!  love that nighttime touch an go pictures! 

@Val: congratulations for building the lightest one!  didn't found the time to watch the entire video, but did you do that all in one turn without quickloading? 

 

Was working on the badge yesterday. Learned that I'm very bad at badges . Going to try again tomorrow...

[Val]

10 minutes ago, Kergarin said:

did you do that all in one turn without quickloading? 

Yes, I did.

[Nefrums]

Ok here is a slightly smaller one.   Second accent was done on LF only.

126,9t

55 parts

 

[Kergarin]

That's a small plane!  And still so much LF left 

This absolutely beats what I'm actually working on, but I still see some room for improvement 

[Nefrums]

Thanks.   There where about 1200 LF fuel left when i started the second descent.  That is 6,75 t to much carried to orbit twice, even counting with an optimistic 55% payload fraction that indicates that a 22t reduction is possible.

Getting the ship balanced is a lot harder in this challenge then usual, as you have to have Col/CoM balance at three stages,

1. Fully fueled with cargo
2. Semi fueled wo cargo
3. Empty with cargo

The second one is usually solvable by transferring fuels between tanks. However I run into trouble as all OX is stored in the front adapter tanks. I had to move CoL further back than than what is optimal for the first ascent.

 

 

 

Edited February 26, 2016 by Nefrums

[Val]

9 hours ago, Nefrums said:

Ok here is a slightly smaller one.   Second accent was done on LF only.

126,9t

55 parts

Wow. Very impressive.

I see that you opted for 3 LV-Ns and 6 RAPIERS(?) in this version and ended up on ~0.4 TWR for the LF-only ascent. Just as I predicted. 

It also fits well with a personal hypothesis I have, that for RAPIER/LV-N hybrids the optimal load per RAPIER is higher than for pure RAPIER builds.

My hypothesis is that 18 t per RAPIER is optimal for pure RAPIER and 25 t per RAPIER for hybrids, with 0.3 TWR if they carry Oxidizer and 0.4 if they don't.

Yours is only 21 t per RAPIER though, so maybe I need to adjust/retest my hypothesis.

Though, I don't envy the balance problems your config has with all the engines at the rear. I opted for a drag hit to make mine easier to balance.

Keep up the awesome. 

[Nefrums]

Yes, You where right, I did not manage to get the 7-2  configuration to orbit on LF only.

I could have moved two of the LV-Ns forward, That might have solved some of the problems.

 

[Nefrums]

I wonder if I can get a ~110t ship with 5 rapiers and 2 LV-Ns to work, that would allow me to mount all engines on the magic drag reducing engine mount plate. Thou then I might need to use radial intakes, instead of shock cones.

Twr of the second ascent would be at best 0.3

 

Edited February 26, 2016 by Nefrums

[Val]

32 minutes ago, Nefrums said:

I wonder if I can get a ~110t ship with 5 rapiers and 2 LV-Ns to work, that would allow me to mount all engines on the magic drag reducing engine mount plate. Thou then I might need to use radial intakes, instead of shock cones.

Twr of the second ascent would be at best 0.3

I won't rule it out, but I'm doubtful. I think it'll be even harder if you make the craft lighter.

While you would be reducing drag by removing the radially attached stacks. The fuselages ballistic coefficient will also drop. Less mass with the same drag, so drag on the fuselage will become more significant, slowing you down faster after airbreathing phase. Not sure how it balances out.

But with the lower TWR, I think, the odds are stacked against you.

I am cheering for you, though. 

Edited February 26, 2016 by Val
Clarification

[Kergarin]

The badges are finally there! please see first post

i hope they are ok?

Edited February 26, 2016 by Kergarin

[Nefrums]

3 minutes ago, Kergarin said:

The badges are finally there! please see first post

i hope they are ok?

They look great!

17 minutes ago, Val said:

I won't rule it out, but I'm doubtful. I think it'll be even harder if you make the craft lighter.

While you would be reducing drag by removing the radially attached stacks. The fuselages ballistic coefficient will also drop. Less mass with the same drag, so drag on the fuselage will become more significant, slowing you down faster after airbreathing phase. Not sure how it balances out.

But with the lower TWR, I think, the odds are stacked against you.

This is quite true...  It might be doable if I save a tiny amount of OX for the second ascent.   I'll probably try to build one on Sunday, as i have no time to play today or tomorrow.

[Val]

8 minutes ago, Kergarin said:

The badges are finally there! please see first post

i hope they are ok?

Thank you. They look good!

[Nich]

2 hours ago, Nefrums said:

They look great!

This is quite true...  It might be doable if I save a tiny amount of OX for the second ascent.   I'll probably try to build one on Sunday, as i have no time to play today or tomorrow.

 I think it wouldn't take much maybe 100 DV worth 

[Val]

3 hours ago, Val said:

I wonder if I can get a ~110t ship with 5 rapiers and 2 LV-Ns to work ...  It might be doable if I save a tiny amount of OX for the second ascent. I'll probably try to build one on Sunday, as i have no time to play today or tomorrow.

I think, I'll try a 4-3 one. I created a couple of craft with that configuration, both for the Single Stage to Laythe and beyond challenge.

The first one I never used.

4 RAPIERs and 3 Nervas. 5.3 km/s dV and 0.32 TWR in LKO. Liquid Fuel Capacity 10120. Dry weight 27.920 t. Full weight 85.940t.

It was only 86 t takeoff weight, but that was before I'd properly figured out Angle of Incidence. I just angled the cockpit down, so the rest of the craft was always at 5° angle. Which looked great on paper, because I was flying prograde, right? I  at myself. It was very inefficient.

The second one was used (see link in my sig).

4 RAPIER and 3 Nervas. 4.0 km/s dV (4.7 with no cargo) and 0.25 TWR in LKO. Liquid Fuel Capacity 10825. Dry weight 36.2 t. Full weight 97.2 t + 9 t cargo.

Both of these were in KSP 1.0.4, so I'll have to check if it's still viable.

[Kergarin]

Even if it might not be the lightest, here is my entry for master:

137.5t  44parts

just a modified version of my standard SSTO

Who Needs a rudder?  had to land powered too, to use engine gimball

2 nervs worked: 30degree ascend until rapier flameout, then gravity turn until 70km, out of the atmosphere 30degree AoA until the nervs glow got me into orbit

 

[Nich]

I am liking the trike more and more

[Val]

Here's a new entry for Master.

115.6 t takeoff weight. 74 parts + 3 for payload.

Craft file

I overshot the approach on the last reentry. ( I got a little cocky) It got a little crazy and I had to Quickload a bunch of time before I could make a non-explody landing. And even so the last landing got weird.

Watch it in 2x speed. It's a bit long.

[Nich]

Ha ha that thing flys more like a fighter then a cargo space plane lol

[Kergarin]

That's a crazy design 

Congratulations for new lightest SSTO! 

Isn't the top mounted nerv negative affected by the rudder?  

Edited February 29, 2016 by Kergarin

[Val]

1 hour ago, Kergarin said:

That's a crazy design 

Congratulations for new lightest SSTO! 

Isn't the top mounted nerv negative affected by the rudder?  

It probably should be, but luckily for me, it isn't in KSP. I didn't actually notice my mistake until I'd done a good part of the mission. I considered restarting and put 2 smaller rudders on instead, but since the LV-Ns exhaust wasn't damaging it, I let it slide. I'll fix it for next version, if there's need for one.

[Kergarin]

Oh sorry, it should have been this emoticon: 

Just corrected it,  better I look a little longer at it next time 

 

Are you sure you don't lose some thrust by this? Once I had some elevators directly behind my engines on an SSTO, and I'm pretty sure my thrust was reduced to zero.

Don't have the time to test this right now. Maybe it just affects airbreathing engines? Or does the distance matter?

 

[Val]

8 hours ago, Kergarin said:

Oh sorry, it should have been this emoticon: 

I like the other one better

8 hours ago, Kergarin said:

Are you sure you don't lose some thrust by this? Once I had some elevators directly behind my engines on an SSTO, and I'm pretty sure my thrust was reduced to zero.

Don't have the time to test this right now. Maybe it just affects airbreathing engines? Or does the distance matter?

Distance does matter. Rocket exhaust would also cause damage to it and eventually make it explode if it was too close. But there were no damage messages in the F3 window.

[Teutooni]

Probably not a winning entry, but decided to tweak one of my heavy SSTO lifters for this challenge (master level). It's a 8 rapier 4 nuke closed drone. It has enough oomph to lift 36t orange tank to geostationary, mun or minmus orbit. It also has a solar panel, 3 docking ports, 8 RCS ports, and many control surfaces, so one could easily get the part count down some.

Weight: 122,015 t + 36,22 t payload for a total of 158,235 t.

Parts: 62 + 3 payload for a total of 65.

 

[PacThePhoenix]

Sooooo.... stuff happened and I haven't been able to work on my SSTO for the past while. I'm really tired of it sitting in my saves doing nothing, so here it is. As I hinted before, it is a very ugly plane . My initial thought when seeing this challenge was "A single orange tank? Pfft, I'll do two", which I am so very close to achieving. The only issue I have with the craft is the lack of dV, ~400m/s short, which isn't bad, but I don't really feel like doing any work on it right now. The TWR is well above 1 so adding more fuel should be no problem. Also, it flies like a skyscraper, made of cows. Aaanyways, it is very likely that I will do a more serious attempt at this challenge sometime in the future, just fyi .

 

[Nefrums]

I finally managed to build a working ship with 5 Rapiers and 2 LV-Ns.  Balancing it is difficult when all engines are at the back.

I managed to reduce the required amount of OX to only a half full Mk3 adapter tank.  

Second ascent is LF only, the ship is then only ~34t so the 2 LV-Ns givas a twr of 0.36

96,7t,  59 parts