Tuesday, May 30, 2006

Tulipa kolpakowskiana? #4

Okay ... here's the last post of the thermal blankets jettison sequence ... or so I hope 9_9 ... I modifed a few of the parameters so that a small forward impulse is given to each blanket upon separation so that they don't runs into the PAO, and it actually doesn't too bad I think .... :
BTW, a Tulipa kolpakowskiana is a specie of Tulip .. in case you were wondering ... The opening of the blankets looks to me like a tulip opening-up ... well at least it does to me ...

Monday, May 29, 2006

Tulipa kolpakowskiana? #3

"bloody perfectionist" ... yep that's right ... That's how Castorp (my partner in crime) called me when I sent him some new screenshots of the thermal blankets jettison sequence ... Obviously he was jocking (or so I like to think ...), but in fact he's right ... I do tend to spend waaaay too much time on little and obscure details ... Really, do I need to spend over 6 hours just to get right a sequence that only last a few seconds? :-\ The worst part is that I'm still not done with it! Yeah ... there is still some details that I'm not satisfied with ... mainly the way the blankets fly away once separated from the service module (PAO) ....

Last Friday, I once again ordered more books from Amazon.ca ... obviously they are Space related: Rocketman and Sputnik and the Soviet Space Challenge ... The second book is the first part of Asif Siddiqi's work, from which I already have the second volume ... but still haven't read it ... So yeah, I ordered it a bit too early in fact, but the idea was to grab it while they still had it ... if you look on Amazon site now, it said "Usually ships within 1 to 3 months" ... :-) Which is exactly what happend when I ordered the second volume few weeks ago ... I snatched the last one they had (at least in Canada) ... hehe :->

Friday, May 26, 2006

Tulipa kolpakowskiana? #2

Following my latest (twisted) idea on a variation of the 3rd theory (see last 2 previous posts), I modified the code so that the blankets only open upon separation of the SA module from the PAO. I have to admit that I haven't have time to scratch my head too much on how/when these darn blankets should open, but here's another idea ... What if there was some kind of mecanism embedded in the blanket that upon command retract (like a cable been pulled) enough so that the opening motion is initiated? That should do it, no? Hmm ... now, if I blend Urwumpe's theory with the one I currently have implemented, the blankets could separate from their attachment points (on the PAO) after reaching a certain rotation angle ... That actualy doesn't sounds too bad, and will definitly get the blankets away from the SA enough so that there isn't any risk of them striking it ...

In any case .. here's a few more screenies on the last iteration of the blankets jettison:

Thursday, May 25, 2006

Tulipa kolpakowskiana?

Late last night (well not that late in fact) I finished implemented a draft of the thermal blankets opening sequence, which I was talking about in my previous post, applying the 3rd theory considered:

As it may be visible on the screenshots, I throw in a bit of randomization to some of the animations parameters, in an (futile?) attempt to make it more realistic looking. Then, I sent a few screenies to Castorp to see what he thought of it and he made the very valuable comment that the motion of the vessel at the moment of the separation of the BO shouldn't have such a large outcome, nor should there be that much difference between each blankets (opening angle & speed). And he's right, as there is no actuator forcing the blankets to open, it is only the motions of the vessel that should make them open (or close), starting with a small backward motion due to the jettison of the orbital module, then with some more of the same motion upon jettison of the service module. Now, here's what I think would be more accurate:
  1. Upon separation of the BO, the impulse given to the vessel make the blankets (which are loose at the forward part of the SA) to start opening slowly
  2. The separation of the PAO jolt the blankets to open more and the SA "pushs" its way out of the blankets as the PAO is going in the opposite direction than the SA.
Now, I'm having an hard time warping my mind around the behavior of the blankets (attached to the PAO) when the motions occurs ... should a force applied to push the BO from the SA make them open or close? The more I think about it, the more it seems that they shouldn't open on their own as the force applied to the vessel during the separation will be transmitted to the blankets throught their attachment point .... which mean that they should rotate towards the SA and not away from it ... hmmm .. how puzzling ... :-

Wednesday, May 24, 2006

Philosophical Question(s)

Lately I have been working on the separation of the Soyuz spacecraft into the 3 different components that compose it. The jettison of the Orbital module (BO) is fairly simple to work-out, altought small details are unknown (to us at least), like does it use pyrotechnic devices or springs and what's the value of the force applied to push it away from the vessel ... Now, the separation of the Service module (PAO) from the Reentry module (SA) is less straight forward to implement mainly because of the question of the whereabout of the SA's thermal blankets that shroud it during most of the flight. What is know "for sure" is that the blankets are attached at the forward part (around the hatch ring) of the SA and also at the forward part of the PAO.

Right now, I'm contemplating the following three different theories (as usual, it is difficult to find one source that doesn't somehow contredict what another source said 9_9 ...)
  1. Prior separation of the BO, the blankets are pushed away from the SA after been cut loose. (as seen in a animation from Anatoly Zak)
  2. After separation of the BO, the blankets are getting loose as now they are only attached at the aft of the SA, so they open like a flower (a bit randomly) before been cut loose when the PAO/SA separation occurs. They then drift away. (Urwumpe's theory)
  3. After separation of the BO, the blankets are getting loose as now they are only attached at the aft of the SA, so they open like a flower (a bit randomly) but stay attached to the PAO when the PAO/SA separation occurs. (as seen on a drawing on a french site)
Now, they all sound plausible, but my preference goes to the third for the following reasons:
  1. I can't tell by looking at all the pictures of the thermal blankets applied to the SA (and also at pictures of the SA without the blankets on) if there is any devices placed behind them to push them away as suggested by the first theory.
  2. It is known that the PAO performs an avoidance maneuver after its separation from the SA, in order to get out of the way and avoid possible encounter with the SA later on. Now if the blankets are detached from the PAO during the separation, they are going to drift around the SA and possibly strike it (for example, when the SA change its orientation). Of course as these blankets are relatively light (guess-estimated at about 1.8kg each) it may not matter much, as the difference of speed between the SA and the blankets will be relatively low ... so the question really is, how cautious are the Russian designers?
Any suggestions or solid source will be very welcome to solve this mystery :-) In the meantime I'll go ahead with that 3rd therory which, the more I think of it, sound the more likely ...

Wednesday, May 17, 2006

Archives gones wild! #3

Woot! Major update to the Project Apollo Archive over the last few days, with over 2200 new or updated images! Yahoo! ... Eh? Surprise that I still talk (a bit) about Apollo? Well, yeah I may have taken a very Soyuz oriented approach to space, but I'm still an Apollo junky, don't worry :-) Here, for example, I finished two days ago Two sides of the Moon, by David Scott and Alexei Leonov, that's an Apollo related book, no? Ok, yeah ... I admit it also talk about the Soviet space program, but altought it is co-authored by one astronaut and one cosmonaut, it is clear that the Scott's part is way more detailed and complete ... so in the end I was a bit disapointed, by the lack of real details on Leonov's part :-

On the Orbiter front, work is continuing at a rather slow pace on my part. Castorp is churning new meshes and update at an infernal pace (7K-OK meshes) and I can't really keep-up :-\ ... As we have switched to Obiter 2006, we are taking advantage of the new beacon API to add some light and strobe effects to the Soyuz. The following screenie show the SA (reentry module) after a night landing with the its post-landing strobe deployed:

The circle that can be seen in the middle of the beacon light is due to the beacon it-self been placed inside of the bulbe of the strobe light mesh. A solution to avoid this not so nice effect, is to make that part of the mesh invisible when the beacon is ON and visible when OFF.

Castorp and I have been going over our resources and checking quiet a few pictures to see how many light beacons (and where) were located on the Soyuz variant we have currently. Needless to said, this is yet again another wild goose chase ... c'mon Amazon.ca! Ship that Soyuz: A Universal Spacecraft book already!

Wednesday, May 10, 2006

Deep space monster(s)!

Nope, it's not some kind of deep sea/space monster, but juste some testing of a couple of new functions from the Orbiter 2006 API (yep it's out since last week!) which allow the modification of a mesh material and texture pretty much on-the-fly. Here we were just testing that tweaking the material was indeed working, ehence that wacko red glow ... but that's kind of a perfect effect for the super heated heatshield during (and post) reentry, I'll said ;-)

That new version of Orbiter introduce some nice things, like the glass cockpit (very useful right now as we don't have any cockpit in the Soyuz), but also a few bugs ... such as the animation one. Let's hope all the small issues will be ironed out in a up-coming patch.

Here's two more screenies:

Monday, May 01, 2006

Tumble dry : low

Over the weekend, I have added the Reaction Control Sytem (RCS) of the re-entry module (SA) of the Soyuz, based on the few data I could gather from either pictures or documents. And, as you could have guessed, there's much room left for guessing. The SA is only supposed to be able to orient it-self before (and during?) re-entry, so it is equipped with 6 thursters (9.85N each). These allow the Soyuz commander (middle seat) to adjust the pitch, roll and yaw during the brief time from separation of the service module (PAO) and parachute deployment (about 12 minutes).

The position and thurst vector of an attitude control thruster is something that is studied with lot of attention during the design phase of any spacecraft. The idea been that, the linear moment created by a thruster need to be cancelled out by another thurster located at the opposite position. In the case of the SA, this rule doesn't seems to have been applied, with only one set thrusters (2 each) by attitude components (pitch,roll and yaw):

While testing the SA in LEO, I have noticed that the roll thrusters are generating some unwanted moments (ehence the slow tumbling). I said unwanted ... but in fact I don't know if it is... What is happening make sense to me, but as we have based our implementation of the re-entry module on sketchy data (thrusters location was guessed from pictures as well as their thrust vectors), it's hard to know if the end result is an accurate simulation ... I guess we need to dig around for more data ... :-