Project Phoenix Capsule

[BruceJohnJennerLawso]

Hey folks,

Figured I might as well start up a development thread for my newest project, the Phoenix Capsule. The Phoenix capsule is intended to be a simple testbed, easy to use, and eventually supporting a wide variety of service module types like nuclear, LOX/LH2, Methane/LOX, solid fueled, and even ion propulsion.

Some screenshots of what I have so far







Currently supports UMMU, properly jettisons the service module, RCS thrusters are working for the SM and CM. Docks are a little bit funny, need some work

Todo list

-LES system, gotta mesh the thing too.
-Sort out how the docking ports are going to work.
-properly set SM parameters from the original vessel class
-Reentry modelling & atmospheric parameters
-Implement Parachutes. I was wondering if anyone would be willing to make a parachute mesh for me to use? I think I'm going to butcher it if I make it.

 

[markp]

Looks good!

Not sure I have time to make a parachute but I could give the ones from my capsule and you could modify that for your addon? I've switched to using a parafoil so I'm not using them any more.

btw what 3d modelling software are you using? Just interested how you made the holes for the thrusters.

 

[Hlynkacg]

Im actually working on a "Gumdrop" CSM to compliment my Spider lunar lander. Contact me if you want to compare notes.

 

[N_Molson]

I was wondering if anyone would be willing to make a parachute mesh for me to use? I think I'm going to butcher it if I make it.

Basically, you create a sphere (not with the triangles method if you want to make a circular hole on the top), you cut it in two, then you deform the hemisphere a bit to create the desired shape. Low-poly cylinders are OK to do the strings.

 

[MaverickSawyer]

What's going on at the viewport? Looks like the mesh is freaking out there...

 

[BruceJohnJennerLawso]

Looks good!

Not sure I have time to make a parachute but I could give the ones from my capsule and you could modify that for your addon? I've switched to using a parafoil so I'm not using them any more.

btw what 3d modelling software are you using? Just interested how you made the holes for the thrusters.

That would be great! I'll just look up the ones in your Mars DRM add-on then? Unfortunately the holes are just painted on to the thruster assemblies, not the best solution, but a fair bit faster than the other way.

Im actually working on a "Gumdrop" CSM to compliment my Spider lunar lander. Contact me if you want to compare notes.

Hmmm, I could launch a few questions at you for sure. I take it none of the gumdrop code has found its way into your tutorials by now?

What's going on at the viewport? Looks like the mesh is freaking out there...

The funny contour to the hull or the texture? The texture is actually one of ice, modified for this purpose, so Ill need to do a bit of touching up on it. I dont know whats causing the peculiar shape by the window either. I tried to hunt down the source of it in Anim8or and in Meshwizard, but its only rearing its head when in Orbiter. Need to dig a little deeper I guess.

Has anyone ever seen any information on what kind of performance could be obtained from a solid core NTR using a fuel other than LH2? Im planning to use LOX for its much higher density, but info is hard to find on the subject.

 

[Hlynkacg]

Hmmm, I could launch a few at you for sure. I take it none of the gumdrop code has found its way into your tutorials by now?

Not directly but parts of Gumdrop have made their way into Spider and parts of Spider have been re-used in Gumdrop.

Consolidating and documenting thier code is a large part of the impetus behind the tutorials.

Unfortunately school and work have been keeping me from working on them. My VC code was an absolute mess and requires some serious dedication to sort out. Once I've done that you can expect a new set of tutorials as well as an update to Spider and the official unvieling of Gumdrop.

I've currently got all the basic flight systems working, the basic framework having been barrowed from Spider, along with Launch abort capability and a rudimentry payload management system.

On the to-do list are Reentry effects/flight model, adding Parachutes, and getting the VC to work.

I posted screenshots of one of my test flights here...

http://www.orbiter-forum.com/showthread.php?p=403657&postcount=5013

 

[MaverickSawyer]

-snip-
Has anyone ever seen any information on what kind of performance could be obtained from a solid core NTR using a fuel other than LH2? Im planning to use LOX for its much higher density, but info is hard to find on the subject.

One suggestion-DON'T!!!! It'll eat the engine. After all, you'll have a really high temperature pure oxygen environment. That'll eat ANYTHING in the engine. If you use something other than LH2, use the liquid methane. You'll have coking issues, but the issue that plagued the NERVA program, erosion of the graphite liner, would no longer be as much of a problem.

 

[Hlynkacg]

One suggestion-DON'T!!!! It'll eat the engine. After all, you'll have a really high temperature pure oxygen environment. That'll eat ANYTHING in the engine. If you use something other than LH2, use the liquid methane. You'll have coking issues, but the issue that plagued the NERVA program, erosion of the graphite liner, would no longer be as much of a problem.

Back in the days of RIFT and NERVA ammonia was the most commonly proposed alternative to liquid hydrogen. The slight ISP penalty in comparison to methanw was trumped by the fact that it was easier to store, and didn't gunk up the engine. Some RIFT proposals had a LOX "afterburner" to boost peak thrust but LOX was never a primary working fluid for the reasons you already mentioned.

ETA:
In the 50 MW NERVA engine studies NASA predicted exhaust velocities of 8 km/s using LH2 and 5.2 km/s using NH3.

 

[BruceJohnJennerLawso]

Back in the days of RIFT and NERVA ammonia was the most commonly proposed alternative to liquid hydrogen. The slight ISP penalty in comparison to methanw was trumped by the fact that it was easier to store, and didn't gunk up the engine. Some RIFT proposals had a LOX "afterburner" to boost peak thrust but LOX was never seriously considered as a primary working fluid for reasons of corrosion.

Did you ever hear any ISP values quoted? Ive been using 600s vacuum for LOX as a guess, but I know its probably not accurate.

 

[Hlynkacg]

You been ninja'd

:ninja:

---------- Post added at 19:12 ---------- Previous post was at 18:56 ----------

I have a whole bunch of studies NASA and Rocketdyne did on NTRs, including results from the NX1 test program, that I've been collecting as reasearch for the Sci-Fi story i'm writing.

For the baseline 50 mw NERVA NASA predicted exhaust velocities of 7.5 to 8 km/s using LH2 and just over 5 km/s using NH3.

Methane was around 6 but introduced too many issues with maintenance as the coking effect would, over time, crud up the engine and prevent effective cooling. This limited the engine's operational lifetime and because NERVAs were supposed to be recoverable/reusable this was deemed unacceptable.

 

[MaverickSawyer]

hmm... What if, once an engine began to coke up, you ran a hydrogen fuelled burn to eat the carbon? Something to think about...

 

[wehaveaproblem]

The funny contour to the hull or the texture? The texture is actually one of ice, modified for this purpose, so Ill need to do a bit of touching up on it. I dont know whats causing the peculiar shape by the window either. I tried to hunt down the source of it in Anim8or and in Meshwizard, but its only rearing its head when in Orbiter. Need to dig a little deeper I guess.

Those dodgy polys on the corners shown in the 2nd pic looks like either a vertex normal or a vertex order problem to me, or something similar.

Unfortunately I don't use anim8or, so not sure what tools it has for changing those things, but its something that can definitely be fixed.

 

[Loru]

I suggest switching to more advanced 3d modelling software (GMAX - free) so you can fix this issues with few clicks

 

[Hlynkacg]

I use Blender, it's open source and thanks to vlad's pluggin can open and save orbiter meshes directly.

 

[BruceJohnJennerLawso]

I suggest switching to more advanced 3d modelling software (GMAX - free) so you can fix this issues with few clicks

I'll try downloading Gmax to take a look-see. I also have blender installed, but I find it absolutely confounding to use in any way. I know I'll probably have to head in that direction eventually, but for now I feel a lot more comfortable with anim8or.

Not as much work on this as with the Shuttle-DB's RCS systems. I plan to give the parachutes from markps add-on a try tommorow. It should be nice to end a test run with a succesful landing rather than a huge BOOM. (moodflows crash sound is great though)

 

[BruceJohnJennerLawso]

Okay, so I thought I would try a quick beta, just to show the fruits of my labours & to explain a problem Ive encountered with the parachutes. I tried the method suggested by francisdrake in this thread

http://www.orbiter-forum.com/showthread.php?t=29533

but the aerodynamics dont seem to work at all. My capsule still slams into the ground at 140 m/s or worse. Can anyone advise as to what aerodynamics I need to add in order for them to work?

Parachutes are from the Mars DRM addon by Markp.

View attachment 11403



If youre reading this markp, would you mind posting the code relevant to the chutes from your Mars DRM?

 

[Hlynkacg]

I'll try downloading Gmax to take a look-see. I also have blender installed, but I find it absolutely confounding to use in any way. I know I'll probably have to head in that direction eventually, but for now I feel a lot more comfortable with anim8or.

I've used all three but prefer Blender for it's ease of customization.

What specifically are you having difficulty with? I could whip up a pretty solid "orbiter meshes for blender noobs" tutorial if I had a better idea of where the hang ups are.

 

[markp]

I used the following to create the drag element when initialising the vessel.

CreateVariableDragElement (&dg,1000.0,_V(0,0,100));

Then I used the following code in clbkPreStep to deploy the parachutes. When dg = 1.0 then the parachutes are fully deployed.

 //parachutes
   if (ap == 2) {
   DelAirfoil(hAirfoil[0]);
   DelAirfoil(hAirfoil[1]);
   hAirfoil[0]=CreateAirfoil3 (LIFT_VERTICAL,   cop1, vlift3, NULL, vlift_c, vlift_s, vlift_a);
   hAirfoil[1]=CreateAirfoil3 (LIFT_HORIZONTAL, cop1, hlift3, NULL, hlift_c, hlift_s, hlift_a);
   SetPMI (ch_pmi1);
   SetRotDrag (ch_rd1);
   dg=dg+oapiGetSimStep() * chute_speed;
   SetAnimation (anim_1, dg);
   if (dg >= 1.0) {
	 ap = 3;
	 dg = 1.0;
   }
   opened=1;
   }

I redefined the airfoil so no lift is produced from the capsule just to keep the aerodynamics simple and isn't really required (if I remember correctly).

Hope it helps

 

[BruceJohnJennerLawso]

I used the following to create the drag element when initialising the vessel.

CreateVariableDragElement (&dg,1000.0,_V(0,0,100));

Then I used the following code in clbkPreStep to deploy the parachutes. When dg = 1.0 then the parachutes are fully deployed.

 //parachutes
   if (ap == 2) {
   DelAirfoil(hAirfoil[0]);
   DelAirfoil(hAirfoil[1]);
   hAirfoil[0]=CreateAirfoil3 (LIFT_VERTICAL,   cop1, vlift3, NULL, vlift_c, vlift_s, vlift_a);
   hAirfoil[1]=CreateAirfoil3 (LIFT_HORIZONTAL, cop1, hlift3, NULL, hlift_c, hlift_s, hlift_a);
   SetPMI (ch_pmi1);
   SetRotDrag (ch_rd1);
   dg=dg+oapiGetSimStep() * chute_speed;
   SetAnimation (anim_1, dg);
   if (dg >= 1.0) {
	 ap = 3;
	 dg = 1.0;
   }
   opened=1;
   }

I redefined the airfoil so no lift is produced from the capsule just to keep the aerodynamics simple and isn't really required (if I remember correctly).

Hope it helps

That seemed to work okay, but Im having a few stability issues. I chose to set my drag factor as depending on (dynamic pressure*mycoefficient), but I get stability problems from it. If you run the ChutesTesting scenario attached, open the chutes & accelerate timewarp to 100x, the capsule ends up ejected into space. A similar issue crops up when deploying the chutes at a high velocity downwards.

Ive included my source in the package as well, just in case anyone wants to take a look.

View attachment 11417