NLSSTO Released

[Jarvitä]

Another thing about NLO re-entry, it seems that no matter how shallow you keep it, the max-G's stay around 10 for a ballistic re-entry. Is is supposed to go ballistic or do you have to fly it like a lifting body to reduce the load?

 

[Eagle]

Another thing about NLO re-entry, it seems that no matter how shallow you keep it, the max-G's stay around 10 for a ballistic re-entry. Is is supposed to go ballistic or do you have to fly it like a lifting body to reduce the load?

Yeah ballistic reentry is pretty much the only way. I can't get the max-g much below 9 gs, usually closer to 10. You can try fiddling with the trim and trying to get a little lift.

If you want a 'technical' reason for why trim works for the NLSSTO and the capsule is the NLSSTO makes micro adjustments using its landing legs, and the capsule uses hydraulics to shift the heat shield a little

 

[Urwumpe]

Another thing about NLO re-entry, it seems that no matter how shallow you keep it, the max-G's stay around 10 for a ballistic re-entry. Is is supposed to go ballistic or do you have to fly it like a lifting body to reduce the load?

G-load will also be constant for a ballistic reentry as it only depends on the initial orbit.

 

[Jarvitä]

G-load will also be constant for a ballistic reentry as it only depends on the initial orbit.

Yeah, that makes more sense, I was just wondering whether flying the re-entry in a lower AOA could lower the load, but it appears to stay about the same, and once you're below 60km it's almost impossible to maintain control with the capsule's RCS until the final descent, anyway.


-----Posted Added-----


Hmm, another issue I've discovered...every time I separate the capsule from the launcher (pressing J aster orbital insertion), it turns around and docks with the launcher. Since the launcher's docking probe isn't extended, it just looks like the capsule is turned around and floating a few meters away from the launcher, but they're docked. Is anyone else having this problem?

 

[Eagle]

Hmm, another issue I've discovered...every time I separate the capsule from the launcher

I duplicated the problem at .1x time accel, doesn't occur for me at 1x. Problem is Orbiter is it doesn't get out of the docking zone fast enough to beat the docking detection computer cycle.

One solution is to increase the speed at which the payload is jettisoned.

 

[eveningsky339]

Hmm, another issue I've discovered...every time I separate the capsule from the launcher (pressing J aster orbital insertion), it turns around and docks with the launcher. Since the launcher's docking probe isn't extended, it just looks like the capsule is turned around and floating a few meters away from the launcher, but they're docked. Is anyone else having this problem?

I've encountered the same problem, but I'll fiddle with it.

As for the ballistic re-entry, perhaps it would be worth adding a sort of inflatable heatshield to create lift? A similar concept is used on the Airman:

[ame="http://www.orbithangar.com/searchid.php?ID=2304"]Airman[/ame]

 

[STSJASON]

I did everything and my desktop still crashes

 

[Jarvitä]

I duplicated the problem at .1x time accel, doesn't occur for me at 1x. Problem is Orbiter is it doesn't get out of the docking zone fast enough to beat the docking detection computer cycle.

One solution is to increase the speed at which the payload is jettisoned.

It happens at .1x and 1x for me, but separating at 10x solves the problem.


-----Posted Added-----


On an unrelated note, I was looking into the physical feasibility of such a launcher, and it seems it's mass ratio is ~10.439, which is within expected limits according to this calculator, although Eagle appears to have invented a new type of aerospike engine with an average exhaust velocity of around 4800 m/s across all altitudes, which is roughly 600 to 1000 m/s higher than today's experimental aerospike engines.

But then again, this is 4am maths, so I'll be happy if anyone wants to correct me.

 

[Eagle]

On an unrelated note, I was looking into the physical feasibility of such a launcher, and it seems it's mass ratio is ~10.439, which is within expected limits according to this calculator, although Eagle appears to have invented a new type of aerospike engine with an average exhaust velocity of around 4800 m/s across all altitudes, which is roughly 600 to 1000 m/s higher than today's experimental aerospike engines.

Yeah, its not completely realistic. I chose 4400 m/s because its approximately the same as the SSME engine (vac). An air augmented rocket could possibly have better performance (but nowhere near ready to fly).

I have read a few articles concerning SSTOs, some proposals actually use lower ISP fuel (kero+LOX or other oxidizers) because it can get a better mass ratio and possibly more total delta v for the same size (and weight) spacecraft. A big reason some people like the idea is it makes the rocket easier to recover because it has less of the eggshell problem. Lots of good information linked to by astronautix.com.

If you no doubt may have noticed, vertical landing can be quite dangerous if problems occur. For that reason, runway landings or other methods of 'dead sticking' are more likely to occur in real life. I may make a lifting body version (with no jettison capability), but that won't be for a while.

Also cool calculator. You should be able to play with the numbers and try out different engine/fuel combinations very quickly. I love how Orbiter makes one think!

 

[Jarvitä]

Another question, if I may: Why did you put a docking port on the NLSSTO at all? From what I understand, it's an unmanned launcher meant to get the NLO to a 200km LEO and land. What's the function of the docking port? (although I admit I find the last 2% of the fuel to be much more useful for orbital plane alignment before separating the NLO, rather than landing).

 

[Eagle]

Another question, if I may: Why did you put a docking port on the NLSSTO at all? From what I understand, it's an unmanned launcher meant to get the NLO to a 200km LEO and land. What's the function of the docking port? (although I admit I find the last 2% of the fuel to be much more useful for orbital plane alignment before separating the NLO, rather than landing).

I actually often do missions without separating the NLO. If you launch the NLSSTO from the Moon or Mars (or refuel in orbit), you have delta v to spare, separation is kind of a waste then. But what mission profile you choose is your call.

(generally, I try to avoid plane changes. Its kind of a waste of fuel. If I wait for a launch window, I can get within .003 degrees. Which is often good enough for rendezvous.) Real spacecraft don't usually perform more than tiny plane adjustments.

 

[STSJASON]

I did everything but my desktop still crashes

 

[Eagle]

I did everything but my desktop still crashes

When does it crash? If it crashes before the scenario starts, you need to download Spacecraft3. If it crashes when you jettison the capsule, you need to re-download my addon from Orbithangar.

If its something else, please give more information.