Project G42-200 StarLiner

[Moach]

I tried your original G42 WIP, and I ran out of fuel before I was able to get to orbit.
Are you basing the orbital entry procedures of the G42-200 based on your old design? I ask because in your original G42, your instructions called for a hold at 20k to build up speed to Mach 7.5 before gaining more altitude.
This is incredibly fuel inefficient as 20k, or 65,616 ft still gives a lot of drag on an aircraft going that fast.
The XR2 by comparison uses 60k (196,850 ft) as it's altitude to get up to Mach 20. Not much drag up there.

Also, what's the max tonnage you're planning for a payload?

hmm... that is inefficient... that is also not correct
you're supposed to hit mach 2.5 at 20k altitude, upon which you then engage ramcasters-low...
at mach 7.4 you should be at al least twice that altitude :thumbup:

if it wasn't a WIP, you'd have blown up the ship, for sure :lol:

i don't remember writing that you should hold for mach 7 at 20k... did i? if so, my bad - that's the altitude for mach 2.5


and yes... the G42-200 should be based on the same system.... no need to change what's already working... tweak maybe....

just remember that the G42 is not an XR-vessel - it's supposed to be a lot more realistic, and you're gonna get to orbit with about 5% or less fuel if all is done right :tiphat:

 

[halcyon]

I only referenced the XR2 for it's altitudes on speed buildup, and it sounds like I misinterpreted the instructions on the old G42.

5% or less fuel left? Will that be enough for intercepting the ISS, making a normal/anti-normal burn for base alignment, and the reentry burn?
Do you plan on separating main engine fuel from RCS fuel?

 

[Grover]

i think a little more fuel should be given to us, it should be enough to get a full payload bay up to 1Mx1M orbit at least

 

[Moach]

the G42 has an OMS thruster, which runs on RCS fuel -- it's activated via the hover thrust axis (if defined) or whatever keys control the hovers on the DG :thumbup:

with it you can reach the ISS and even de-orbit later on

 

[Schimz]

wow that looks unstable, wing chord so far behind the vessel? must have some pretty heavy kit at the back to balance the whole thing out

At least 150t for the mk1. Reactor, nanocollider and the 5 engines for the big parts.

 

[Moach]

i think a little more fuel should be given to us, it should be enough to get a full payload bay up to 1Mx1M orbit at least

if you plan on taking off with a full bay, you should probably consider using the DARTs (Disposable Auxiliary Rocket Thrusters)... i've not modelled those yet, but they are in plans, for the -200 as well :thumbup:

thay are small solid boosters which are attached behind the ramcaster exhausts, they have just under 1min. of burn in them, which is not much, but gets you off the ground pretty fast, even with a heavy payload...

it's not really a departure from the SSTO concept... not if you consider that even C-130's may use JATO rockets to boost out of small airfields... plus, they are made to be cheap and disposable... and are not required for the majority of routine flights

drop-tanks are also another planned flight-aid... several sizes should be available, although use of heavy ones is mostly bound to the use of DARTS as well, since large drop-tanks impose quite a deal of extra takeoff mass - unless you've got a light payload bay...

many combinations should be possible, i guess

 

[theflyingfish]

I forgot to ask one last question. After seeing this thread, I downloaded the most recent G42-100 WIP and noticed that many of the Flight Computer MFD's, such as the Hull Temp and Engine Info Displays were simple dummy screens, and many of the buttons were inactive. Are you planning to increase the functionality of these screens? I really liked the design of the Hull Temp screen, with the dual bars for DynPressure and Tempurature. :thumbup:

Also, have you thout about it's name? G42-200 seems like such a small name change for such a radical change in design. How about the G42-XLXS (eXtremely Large, eXpensive Ssto)? :thumbup:

 

[Izack]

Uh, it would be nice if the OMS thruster weren't defined as the hover thruster, since there is no OverrideFull key for hover thrusters like there is for main and retro. You might look at what the Hyperdart does, with a switch in the VC that toggles the main engines between aerospike (for ascent) and OMS modes. :tiphat:

 

[Moach]

I forgot to ask one last question. After seeing this thread, I downloaded the most recent G42-100 WIP and noticed that many of the Flight Computer MFD's, such as the Hull Temp and Engine Info Displays were simple dummy screens, and many of the buttons were inactive. Are you planning to increase the functionality of these screens? I really liked the design of the Hull Temp screen, with the dual bars for DynPressure and Tempurature. :thumbup:

Also, have you thout about it's name? G42-200 seems like such a small name change for such a radical change in design. How about the G42-XLXS (eXtremely Large, eXpensive Ssto)? :thumbup:

about 'em dummy screens... that's what i meant by W-I-P (Work-In-Progress) - i'm not done there... there's a lot left to do... those MFD's that don't do anything are part of the progress yet not made...

those dynpressure and temp bars will be a critical instrument once i code for structural load and heating... at which point, doom becomes a real possibility

i though a lot of the name... i really like G42... and although it looks very different, concept-wise, the -200 is really not such a major change... same engine setup, same wing shape, similar cabin and cargo bay....

plus, as the -100 model was never finished, it stands as an experimental concept demonstrator, which lead to this new revision of the design... who knows, it may even change some more before i'm through with it... :lol: (unlikely)


and a G42 is not that expensive (as far as spacecraft go)... it's meant to mnake spaceflight more accessible, so it shouldn't cost as much per launch as a shuttle or alike.... development costs should be unimaginable, but don't worry - my Sim-Self is really, really rich :thumbup:

---------- Post added at 04:49 PM ---------- Previous post was at 04:48 PM ----------

Uh, it would be nice if the OMS thruster weren't defined as the hover thruster, since there is no OverrideFull key for hover thrusters like there is for main and retro. You might look at what the Hyperdart does, with a switch in the VC that toggles the main engines between aerospike (for ascent) and OMS modes. :tiphat:

i thought of that - just might go that way - thanks for the heads-up

 

[Grover]

i always found that flying having to use the hover thrusters was a real pain, you should simply have a VC toggle switch that redefines the [orbiter] main engines as the OMS engines, and then make sure they can be toggles back as well, in case you either have a ballsed up flight and need engines again, or if you accidentally toggle it, or if you refuel and then take off again

and on a similar topic, will there be re-fuelling in this like the XRs? and if so i have an idea to prevent cheating: when landed, you can only refuel when within 10Km of a base marker, so you cant just land ON the ocean, get fuel from the dolphins and then fly back home

also, realistic physical systems would be nice... in fact, just post an up-to-date hull spec and ill think of some systems to add and where they go.

good luck!

 

[Moach]

i always found that flying having to use the hover thrusters was a real pain, you should simply have a VC toggle switch that redefines the [orbiter] main engines as the OMS engines, and then make sure they can be toggles back as well, in case you either have a ballsed up flight and need engines again, or if you accidentally toggle it, or if you refuel and then take off again

and on a similar topic, will there be re-fuelling in this like the XRs? and if so i have an idea to prevent cheating: when landed, you can only refuel when within 10Km of a base marker, so you cant just land ON the ocean, get fuel from the dolphins and then fly back home

also, realistic physical systems would be nice... in fact, just post an up-to-date hull spec and ill think of some systems to add and where they go.

good luck!

yeah, i'm gonna make a switch for the OMS selector... no more you'll need to use the hovers... they are never used at the same time as the mains anyways...

and the dolphins should have plenty of good fuel - you know... they are the 2nd smartest species on this planet... the 3rd being us humans, you know.... :lol:

i'm not certain how refualling will be approached at this point, but rest assured - it eventually will be simulated :thumbup: - as for "cheat refueling", by the very nature of obiter users, it's safe to just leave it up to chance... it's not like it disbalances anything... if you think it's cheating, just don't do it

tho it wouldn't hurt to add some cheat-proofing... just so one doesn't "accidentally" break his own realism... not worth dwelling on it tho... it's not a competitive thing, so no-one's gonna exploit a harmless little "miss-feature"

 

[Izack]

and on a similar topic, will there be re-fuelling in this like the XRs? and if so i have an idea to prevent cheating: when landed, you can only refuel when within 10Km of a base marker, so you cant just land ON the ocean, get fuel from the dolphins and then fly back home

Really landing within 10km from your base, or even 10m from the runway, will have pretty much the same effect on vessel systems as landing in the ocean, i.e. it will get torn apart. The only difference is the presence of rescue personnel and fire extinguishers.

 

[Moach]

Really landing within 10km from your base, or even 10m from the runway, will have pretty much the same effect on vessel systems as landing in the ocean, i.e. it will get torn apart. The only difference is the presence of rescue personnel and fire extinguishers.

good point - i guess this would just come down to a different "you-died" ytpe message being shown... :lol:

but at that point, you already dwell in shame... no escape from that

 

[Grover]

i meant that after landing, having taxi'ed away you can refuel within 10Km, which is a comfortable radius to completley encompass even the largest bases, in fact, make it a 5-6Km radius, who has a 10Km runway really...

 

[Moach]

i meant that after landing, having taxi'ed away you can refuel within 10Km, which is a comfortable radius to completley encompass even the largest bases, in fact, make it a 5-6Km radius, who has a 10Km runway really...

ah, well, that makes more sense :lol:

 

[Grover]

i just had a thought about the RAMCASTER engine setup:

wouldnt the afterburner not work entirely as a rocket engine, since a rocket is far more complex than a combustion chamber filled with fuel and oxidiser, and the entire afterburner would require reconfiguring during the RAM/SCRAM ascent to have it ready for orbital insertion.

i think you'd need a turbine generator mounted at the just above the air intake (inside the craft) that would pressurise the airflow into the jet engine, to turn the jet which would then be able to power the afterburner, assuming that oxidiser and fuel are then injected into the exhaust/afterburner

unless of course my physics is a little dodgy, and you could actually seal the front of the afterburner and fill it with fuel :hmm:, but i was under the impression that the exhaust of a rocket engine was very complex, with fluids moving all throughout the casing of the nozzle...

other than that, i think there's a possibility you would have to put another rocket engine into the mix if you plan to keep it realistic (depending whether or not its realistic to use an afterburner as a rocket)

sorry to be the awkward guy and all...

 

[Izack]

[...]since a rocket is far more complex than a combustion chamber filled with fuel and oxidiser[...]

It's not, really. :lol:

(At least, not any more than a car engine is more complex than a series of combustion chambers pushing rods turning shafts.)

Although...the chamber will have to deal with much greater expansion in high-altitude rocket mode than in airbreathing turbine or afterburner mode at 20km. How will this be dealt with, I wonder? :hmm:

 

[Grover]

an adaptable exhaust nozzle? changing shape somehow, yet remaining strong enough to withstand the forces it is battered with...

 

[Moach]

i just had a thought about the RAMCASTER engine setup:

wouldnt the afterburner not work entirely as a rocket engine, since a rocket is far more complex than a combustion chamber filled with fuel and oxidiser, and the entire afterburner would require reconfiguring during the RAM/SCRAM ascent to have it ready for orbital insertion.

i think you'd need a turbine generator mounted at the just above the air intake (inside the craft) that would pressurise the airflow into the jet engine, to turn the jet which would then be able to power the afterburner, assuming that oxidiser and fuel are then injected into the exhaust/afterburner

unless of course my physics is a little dodgy, and you could actually seal the front of the afterburner and fill it with fuel :hmm:, but i was under the impression that the exhaust of a rocket engine was very complex, with fluids moving all throughout the casing of the nozzle...

other than that, i think there's a possibility you would have to put another rocket engine into the mix if you plan to keep it realistic (depending whether or not its realistic to use an afterburner as a rocket)

sorry to be the awkward guy and all...

you are correct to say that rocket engines are complex machines - well, liquid fuel rockets are... solids, not that much - those are more on the dangerously-simple side :hmm:

anyhow, a lot of the things you'd find in such a rocket, are pretty much available (although not exactly alike) in a turbine engine as well...
now, notice that there are various of liquid-fuel rocket engines... some are more turbine-like, others not so much...

the "RT-66 TurboCaster" engines fitted in the G42 are more or less similar to these: [ame="http://en.wikipedia.org/wiki/Reaction_Engines_SABRE"]Reaction Engines SABRE - Wikipedia, the free encyclopedia[/ame]

but then, ignore everything forward of the turbine compressor... that's the SABRE pre-cooling system, which the G42 doesn't need, since those engines are replaced with the RAMCASTERs upon mach 2~2.5

and then add a modestly-sized bypass duct and a some other stuff, and there you have it :thumbup:

that's how i believe the turbo-rockets should work.... unless my "science" fails me once again (like that time when i had the intakes placed above the wings... that was un-smart :lol

 

[Grover]

... unless my "science" fails me once again (like that time when i had the intakes placed above the wings... that was un-smart :lol

well... about that...

but i do see the science in it, i just doubted it for a moment

and i meant to ask before: can we have some expected [rough] specs of the ship?ones like
weight
fuel mass
Dv after scram stage

and for my own use;
landing gear wheelbase
craft length and wingspan (for all configurations)
and a rough turning radius for the beast*,

*im amidst making a spaceport in central Africa designed to accomodate XR5s, i would be devastated if this craft wasnt compatible with my taxiway system.

also, i might make a tug for it in UGCO if i can work out a nice way to do it, and if i can have a model to build my tug around (i get EXACT measurements from your model, so mine fits perfectly)

and finally, when do we get to see a model of this? if you are doing textures first, i suppose it would be a while, but i cant wait to see it (do the meshes first, then all the coding, so we get to see it nice and early)

thanks man!