Discussion LKS inspired shuttle concept.

[Urwumpe]

Sure, but it would be more realistic.

Of course, but remember, Loru is a GFX veteran, he is more involved in making meshes than in working "under the hood". He could of course take an existing launcher add-on and put more work into details of the payload - but Orbiter is not the reality and you can do what pleases you.

If I want to launch a few hundred bags of concrete to Mars, I am free to do it.

 

[K_Jameson]

If I ask for the better placement of my spaceplane, is because I take realism into account. Anyway
, obviously we are all free to make anything we want!

 

[Urwumpe]

If I ask for the better placement of my spaceplane, is because I take realism into account. Anyway
, obviously we are all free to make anything we want!

Well, you know, when we speak of reality in Orbiter, we actually mean "scripted reality". :lol: That means, its all fake, but hell, doesn't it feel like reality?

Just as example: The most realistic simulation of a human crew in Orbiter is still the OMB. Which is pretty amusing.

Would I make a realistic Space Shuttle add-on, the first thing that you would see is a Paypal prompt to transfer 1.8 billion USD to me. No bucks, no Buck Rodgers.

 

[PhantomCruiser]

I have a cobbled together MAKS lifted by Energia-M, but the MAKS is not my mesh (and it's sort-of working with SC3/generic vessel). But you and I are of similar thinking on this it would seem.

 

[K_Jameson]

Sidemount, Viable: YES, Safe: NO

Inline, Viable: YES, Safe: Safer than sidemount, at the very least.

I don't want to resume old and unpleasant discussions, but I think that with some measures, sidemount can be reasonably safe.
Surely with sidemount we have two problems:
1) the crew is closer to the explosives (fuel tanks) and this can reduce the safety margin during an abort (assuming that we have a LES). At the times of Eridanus, we have tried to push the cabin farthest and highest possible (this is why the "weird" placement of that spacecraft, other than the need of distinguish better from STS). But this is not necessarily a game-stopper;
2) the insulation of a cryotank, typically foam, is prone to detachments; an alternative coating must prevent detachments of materials or ice (that is much worse). An alternative (as in Eridanus) is a protection for the spacecraft's fuselage, that, in turn, adds some dead weight.

OK, Inline is simpler and safe with less complications, but with very large spacecrafts (especially with very large wings) seems aerodynamically undesirable (this is what told us the engineers we consulted at the times). Surely the Quasar/Eridanus stack appeared "instinctively" more fragile in the inline configuration rather than in sidemount. With the small Lorus spaceplane, maybe the two configurations are equivalent.

 

[Urwumpe]

You could also move the tank insulation into the tanks. But that increases the manufacturing costs a lot.

 

[K_Jameson]

You could also move the tank insulation into the tanks. But that increases the manufacturing costs a lot.

we haven't the risk of some pieces of foam that detaches into the propellant, blocking the feed lines or sucked into the engines?

---------- Post added at 06:18 PM ---------- Previous post was at 05:59 PM ----------

I think the other advantage for the space shuttle was that the SSMEs were recoverable and of course the only way to have this was to have it sidemounted.

In fact, the SSME's maintenance after flight costs more than building new engines built from the beginning to be expendable...

 

[Urwumpe]

we haven't the risk of some pieces of foam that detaches into the propellant, blocking the feed lines or sucked into the engines?

Depends on how you apply the foam. Foam blocking the feed lines could be a minor problem (You could make sure that no large pieces enter the feed lines, or you could use the internal structures of the tank for arresting the foam), but once it reaches the turbo-pumps the foam is just making funny colors in the exhaust. Such feed lines are huge, on the Space Shuttle the main feed lines had 43 cm diameter before branching off into three 30 cm lines.

In fact, the SSME's maintenance after flight costs more than building new engines built from the beginning to be expendable...

That is not quite correct - the SSMEs are really expensive, but you can also hardly replace them that easily because of their really great performance. An expendable SSME would still be very expensive. A cheaper engine on the other hand, like the RS-68, does not quite match their performance (which was why the first Ares V iterations required vastly larger tanks - too large for the available tools)

The problem with the SSMEs had been, that the onboard diagnostics had not been good enough to really replace manual checks. The hope initially was, that improving technology allows diagnostic systems that reduce the costs over a number of blocks, which gradually increase MBTF of the engines. But that did not happen to the SSMEs, while other newer engines clearly profited from the technology improvements.

 

[K_Jameson]

Such feed lines are huge, on the Space Shuttle the main feed lines had 43 cm diameter before branching off into three 30 cm lines.

Yeah, i've studied it in the old days of the Jarvis HLV designing. :thumbup:

An expendable SSME would still be very expensive.

this is sure. Even the RS-68 engine, conceived to be somewhat "cheap" and less sophisticated, has turned to a costly engine.

 

[MaverickSawyer]

Gonna throw my hat into the ring here and pitch for a 2.2 MN Lox/CH4 engine instead of the LH2/Lox engine, and clustering them on your boosters to replace the RD-170s. They'd be possibly reusable on the boosters if you design them for recovery.

What engine am I suggesting? Why, the BE4, of course.

 

[Loru]

Sounds like an Energia-M to me, which was two RD-170 boosters and a single RD-0120M engine (2MN thrust).
http://www.astronautix.com/lvs/energiam.htm
But your empty masses are pretty low in comparison.

Well - those are preliminary numbers. I need to poke around more to find best solution. LV can be then utilized as LV in 20-30 tons to LEO range.

Loru, why you can't size your orbiter for already existing rockets of your inventory instead of making new rockets every time?

Themis-A as relativelly weak rocket couldn't handle it and I need this shuttle to ferry full crew of my space station / mars expedition (planned). HCLV on the other hand is too heavy and using 80 ton capable rocket to launch ~25 ton spacecraft is bit wastefull.

2) the insulation of a cryotank, typically foam, is prone to detachments; an alternative coating must prevent detachments of materials or ice (that is much worse). An alternative (as in Eridanus) is a protection for the spacecraft's fuselage, that, in turn, adds some dead weight.

I can imagine thin sheet of aluminium or other lightweight material on the shuttle facing side of exterior. If it'll coded as an "adapter" it could be removable for unmanned inline launches.

Gonna throw my hat into the ring here and pitch for a 2.2 MN Lox/CH4 engine instead of the LH2/Lox engine, and clustering them on your boosters to replace the RD-170s. They'd be possibly reusable on the boosters if you design them for recovery.

What engine am I suggesting? Why, the BE4, of course.

That's interesting idea. Quick calculation for boosters gave additional 30m3 of tank (higher ISP and reduced fuel load by few tons to achieve same dv of the booster) however I need to do more precise calculations for that including ox/fuel misture ratio.

 

[MaverickSawyer]

That's interesting idea. Quick calculation for boosters gave additional 30m3 of tank (higher ISP and reduced fuel load by few tons to achieve same dv of the booster) however I need to do more precise calculations for that including ox/fuel misture ratio.

Reports indicate that the BE-4 will be leaning (pun intended) towards an ox-rich mixture for the staged combustion. Dunno how that affects the ISP, but I'll see what else I can shake loose.

EDIT: Straight from Blue's webpage: BE-4 Fact sheet (PDF)

 

[Loru]

Reports indicate that the BE-4 will be leaning (pun intended) towards an ox-rich mixture for the staged combustion. Dunno how that affects the ISP, but I'll see what else I can shake loose.

I'm not worried by ISP as much as fuel and oxidiser volumes. LCH4 has around half density of RP-1.

 

[Urwumpe]

I'm not worried by ISP as much as fuel and oxidiser volumes. LCH4 has around half density of RP-1.

Yeah, for boosters a too large envelope can be annoying since they increase drag during maxQ. Also CH4 could be overdesign, since CH4 reaches a high specific impulse and thus, reaches its peak performance in momentum transfer shortly around or even after staging.

 

[K_Jameson]

Wait... now that I think about it... what happened to your XR-3 project, Loru?
Sorry for the OT

---------- Post added at 09:11 AM ---------- Previous post was at 08:50 AM ----------

Oh and... I was reading your table in the previous page and I noticed that for LOX/LH2 you used a mixture ratio of 5, instead of the more common and optimal value that is around 6.

 

[Lmoy]

Wait... now that I think about it... what happened to your XR-3 project, Loru?
Sorry for the OT

Apparently it's on hold, I guess. Honestly, I'd rather see some new realistic space planes in the vein of Eridanus (only like, with not-insane aerodynamics) than more XR series. But that's just me.

 

[ISProgram]

Wait... now that I think about it... what happened to your XR-3 project, Loru?

Last I heard it was coming out on a Tuesday.

 

[K_Jameson]

I'm with you, Lmoy. Only I see that Loru, across the time, was continuously involved in new spaceplanes... this is at least the fourth I hear about! And at least two or three are very similar... for instance I don't see these great differences between this concept and the Starchaser's one. No offense intended!

---------- Post added at 01:19 PM ---------- Previous post was at 01:14 PM ----------

Oh and I'm sorry if the Eridanus aerodynamics are perceived to be so bad by some users... during the development and immediately after the release, did not seem so. Now I don't see how to fix it (Fausto is gone), unless rebuild the entire code from scratch...

 

[Lmoy]

I'm with you, Lmoy. Only I see that Loru, across the time, was continuously involved in new spaceplanes... this is at least the fourth I hear about! And at least two or three are very similar... for instance I don't see these great differences between this concept and the Starchaser's one. No offense intended!

Well, this one is intended as solely a crew transport, whereas Starchaser is intended as satellite retrieval/maintenance and station support. Starchaser could definitely function as a crew transport, but it's more economical to use a smaller and lighter spaceplane for that purpose if you aren't also hauling cargo up (which can be done safer with unmanned delivery systems anyway). So overall, this seems like a really good idea to me.

 

[K_Jameson]

The cost is amortized with the use and a single design is used twice. Maybe a single, modular vehicle with a interchangeable cargo bay / crew compartment? Again, no offense intended, i'm only discussing... even FOI has in fact two different spaceplanes, Eridanus (multipurpose) and Delphinus (crew only), but in that case they are VERY different beasts (Eridanus is almost ten times Delphinus by mass).