Moach: I've just seen the G42-200 for the first time a few days ago. A few remarks:
First, the mesh and texture work is superb! Among the best I've ever seen. No surprise if you're in the game industry, but still. I've been building model a/c for FS for years, I am IMPRESSED!! The s/c itself, the cockpit, all the animations, it doesn't get any better than this. :tiphat:
Next: this bird flies beautifully. Response to stick-inputs is just right for a bird this size, all 3 axes rotate in a very realistic way. You have that nailed!:thumbup:
Now: I'm in the Science Biz, not the game biz, so my take on the design of the airframe and propulsion system does contain a few critical remarks.
1. The reason for the blunt nose and leading-edges on the space shuttle is to separate the shock-wave at high mach numbers from the surfaces. The compression at the shock-fronts is what causes the temperatures to go so high, of course, and a sharp projection sticks out into contact with the superheated air. No material can withstand this, even the silica and the carbon-carbon used on the Shuttle thermal protection system. This was Max Faget's discovery back in the late 50s and it's still valid today. The nose of the G42 is blunt enough to do this, but the wing leading-edges are too sharp. The nose at the cockpit level is TOO blunt though: this part of the fuselage would be in contact with the shock at high Mach numbers; even with the shield-visor,the front part of the fuselage would be in contact with the compression-heated air and would not survive. The upper part of the fuselage behind the blunt nose needs to slope back much more. The Shuttle avoids having the cockpit and forward fuselage exposed to the superheated shock wave by coming in a a high angle of attack (the Shuttle's ascent through the atmosphere was pretty steep, most of the really high-speed phase of ascent was above the atmosphere); but a SCRAM-powered bird cannot do this; AOA would have to be smaller both during ascent and descent. A better design would be a blunt nose with a sharply-tapered fuselage behind.
2. The place where the cylindrical fuselage joins to the SCRAM-caster structure looks very much like the similar structure between the fuselage and the "six-pack" structure on the XB-70. This worked on the Valkyrie at Mach 3, but it requires a very sharp leading edge at front. This would not survive compression heating at higher Mach numbers. You have a nicely-done wing-body-blended structure further aft; this should be carried forward of the scram-caster inlet. This would look like the "chines" on the SR-71. Which leads to:
3. The payload bay is just a little too narrow. A Leonardo ISS resupply module is just a tiny bit too wide. Changing from a circular cross-section fuselage to a more triangular one will allow a slightly wider fuselage and a slightly wider payload bay, and enough room for a manipulator arm on the shelf on the port side.
I'd replace the circular cross-section forward with a flat-bottomed shape, more triangular in cross-section (but circular from the payload-bay doors up), The upper surface about the same as that of the fuselage at the wing-roots, the flat-bottom flush with the top of the Scram-caster inlet. With a blunter leading-edge on the wing and chine leading edges, carbon-carbon ought to be OK for the leading edges, and silica would work for the flat bottom.
If hydrogen is the fuel, you'd need more volume in the fuselage. I'd widen the fuselage by about 15-20%. This would enable a wider payload, bay also. The problem with hydrogen is the low density, even in the slush-phase form.
4. The rendering of the exhausts in all the propulsion phases is really nice, but I'm concerned that the Scram-caster thrust is too high. For the kind of thrust you're getting from the Scram as is it, I think you'd need an air intake much larger. 1 meter/sec^2 acceleration is very optimistic for a scram of any kind. I would reduce the fuel-flow during Scram operation and make this part of the ascent longer.
5. The folding wings are a nice touch, compression-lift like the XB-70, great idea, but this would come with a pretty severe weight-penalty. All the actuators and hydraulics are going to involve a lot of mass. You might want to re-consider this. I'd move the canards further aft, increase the span and chord, with a variable-sweep feature for the canards in place of the folding wings. I'd want a longer span on the canards because I'd reduce the span of the main wings, outboard of the turbo-rockets. Thicker wings would obviate the need for the tilt-up feature, and I think you'd need thicker wings anyway because of the leading-edge issue.
All this sounds like major changes to the airframe, but I think that it would be less of a change than it sounds. You have something like the right cross-section with the existing wing-body blending, just carry that forward. Sorry about the fuselage-scram box junction, you obviously took a lot of care with that, but like I said above, I don't think such a structure would survive hypersonic flight. Same goes for the cockpit.
I'm working on an SSTO myself, in fact I've been working on it for years. I'm on the 4th redesign, now. I hope mine turns out even remotely close to being as nice as the G42.
:hello:
Alright! that's something i can work with! - many million thanks for this valuable input - :thumbup:
this sort of advice is exactly what this project depends on so it can feature a design which is both eye-catching and realistic (sadly, unlike the majority of addons, where one seems to almost certainly exclude the other)
although i'm a game dev professionally, my hobbies and general "extended field of expertise" do include a handful of real-world flight hours, plus an unimaginable hour count on the sim....
i also did take an aerodynamics course (more of an open, guided workshop, really) as a teenager, where i got kinda good at "eyeballing" dimensions for building various made-up yet fully air-worthy balsa airplane models
well, some more air-worthy than others, but invariantly, none of those models ever broke the speed of sound...
so i expected my design "guesstimates" for this craft to be off to a generous degree, and i depend on people more knowledgeable on the matter who are willing to steer the concept onto the proper direction -- you, my friend, just did! and i thank you for it :speakcool:
the idea of a flat surface integration between the ramcaster scoop and nose structure is something i've been tempted to pursue since i last got any chance to work on this bird...
that and a little extra room in the bay (we're only about a foot short of STS-compatibility) add to the benefits of a semi-large revision at this advanced state of development....
i did scrap the project and restart it once already (which is why it's called the '200) - i have no reservations towards taking a step back if it means ten more could be taken forward from then - still, this isn't any as drastic as that first time anyways... :lol:
worth considering tho, is that the G42 is nevertheless, a futuristic bird - we're not working strictly under the constraints of current/shuttle-age tech...
i like to think of 40~50 (good) years of aerospace development ahead - it seems imaginable there are ways to allow a more narrow profile reaching higher mach numbers if cutting-edge materials of 5 decades from now are employed (i like the idea of carbon/ceramic composites and aerogel) :hmm:
...and gladly, the fuel is not hydrogen - let's just say it's "something else" for the sake of the concept
thanks again for the input - lots to think about from this! -- i'll keep you posted whenever any new progress is made that warrants mentioning
edit* on a smaller note... if the canards were any further aft, where would the cargo bay go?? they could retract forward, from a hinge on the back of the slot, but would that not add too much stress on the whole structure? (turbulent air penetration, etc?)