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Zorg

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Posts posted by Zorg

  1. 2 hours ago, CobaltWolf said:

    By the way, @Zorg, were you planning on continuing that setup with the new parts?

    I haven't decided yet. I like the idea behind the way you did previously and it makes sense to differentiate balance wise. However adding that tag would complicate the ability to create some interesting Atlas test flight variants that had markings around decoy and scientific passenger pods. My thought was to make decals for those since its not feasible to have all those as texture variants...

  2. On 3/11/2024 at 2:39 AM, DaveyJ576 said:

    @Zorg, outstanding work as always. The attention to detail is amazing. Thank you for all of this work.

    By the way, the earliest version of the MA-1 powerplant that flew on the first three Atlas A test flights (Atlas 4A June 1957, Atlas 6A in September 1957, and Atlas 12A in December, 1957) actually had cone-shaped nozzles for the two booster engines. The first two flights ended in failure, but 12A succeeded in flying a 600nm flight. As part of the crash engineering troubleshooting process following the first two failures,  Rocketdyne shifted to bell-shaped nozzles, but they were not ready for the 12A flight. Atlas 10A flew successfully on January 10, 1958, the first with bell-shaped nozzles, establishing the standard for all further Atlas flights. This was almost a SpaceX style iterative approach to rocket design. Build it, fly it, blow it up, fix it, fly it again. In this case they were doing it because they had no choice due to limited (as compared to today) ground testing capabilities and not because it was part of the Rocketdyne/Convair corporate mantra.

    Just a historical FYI for everyone, don't spend the time redoing the nozzles.

    Interesting, didn't know about this tbh. I've got a fair amount of Atlas A pics in my refs but none of the conical nozzles. But probably not worth doing even if I had though,  if as you pointed out only a handful of flights used them.

  3. 36 minutes ago, septemberWaves said:

    What is the function of the pipe that sticks out below the Atlas skirt, and why was its shape changed after Atlas A?

    Gas generator exhaust pipe for the booster engines. As for why the shape changed? Who knows... theres a million small differences among different Atlas variants. This was one that I happened to notice and was feasible to model due to the way the meshes and textures were split :P

    The pipe is positioned where it is since the turbo pumps for the booster engines were located centrally in the skirt.

    The early MA-1 power pack had a shared turbo pump and gas generator for the boosters, from that point on they each had a separate pump (but still co-located in the center of the skirt) but shared gas generators.

    The exception is the Atlas E/F engines, the MA-3 pack, where the USAF wanted the engines to be easily removable for maintenance independently. So those engines are completely separate with all their machinery located near the engine bell like a typical engine. This is also why the Atlas E/F booster skirt is significantly different in shape to accomodate the bulkier engine package.

    I2u6ike.png

    G6R36HY.png

    NVvOOyC.png

    Here's an Atlas F with independent boosters

    fo91Afa.png

    You can see the Atlas E/F skirt shape on the far right here (this was before I modelled the pipe on the other skirts)

    wzBDqCL.png

  4. 1 hour ago, GoldForest said:

    Is that a Saturn themed Atlas? Or an actual official paint scheme used on a select one or few launches I don't know about? 

     

    It was an actual scheme on some Atlas A launches. (I need to recolour the top of the avionics pod, it was a bit faded in the reference picture I was looking at earlier)

     

    16450763219_9bd68e3a8c_b.jpgAtlas 10A on pad--Tower Away box by SDASM Archives, on Flickr

    1 hour ago, GoldForest said:

    Also, been meaning to ask, is the original 2 engine engine mount going to be made? 

    I believe the 4th picture I posted answers that question already :P

  5. Work on Atlas continues at a slow pace. But it is continuing.

    GSE cutouts and more details on Atlas A and D skirts

    xQSj6Di.png

    EVWVhYn.png

    idk if I posted this before but the standard aft tank

    ekmAQ1i.png

    A new aft tank just for Atlas SLV-3X "Fatlas" so the H1-D can actually fit on it properly (you need to rotate it 45 degrees though.

    trHlcCG.png

    And a preview of the new tank setup thats been planned.

    1iwv1UW.png

    The annotation here isnt comprehensive. For example Atlas H MSD would be a base tank + SLV3C (&D) cylindrical extension + Atlas H conical adapter.

    An SLV-3A would be base tank +SLV 3A extension+ 0.9375m conical extension etc.

  6. 11 hours ago, Pappystein said:

    http://www.generalstaff.org/Space/Space.htmhttp://www.generalstaff.org/Space/Space.htm   <<<----  New location for the Alternate Wars/BBOW pages you are referring to Zorg (this is the main space page)   It is slowly being updated with the missing content like you are refering to... IIRC Achive.org has some good backups of the old Alternatewars.com/BBOW page (if I am remembering the URL correctly)

     

    Sadly some of the files are archived on archive.org and the rest are not :(

     

     

    Oh the engine pages werent there last time I checked, hope it gets uploaded at some point. But yeah archive.org was able to recover most of the pages on the old site I think.

  7. On 2/4/2024 at 2:50 AM, Pappystein said:

    That is in a separate Agena Hypothetical article....   Sadly, there isn't a huge amount of info other than it had NOTHING to do with Agena, and it was just a "It is in the news it is being retired so a good name to use..."  Kinda like Atlas itself :D

    I use Real names patch in the BDB Extra folders... so I only know the real names off the top of my head... not the BDB-ified names :D

    **BUT** going through the files it is the PXR-129

    Sorry missed the first part of the question... the RL20 WAS a developmental engine that sometimes falls under the HG-3 name that is floated arround.   It isn't a HG-3 since that was an internal name from Rocketdyne as I recall, but it is the same performance category.   Zorg has the facts on that (I don't have the refrences he does for the RL20)

     

     

    HG-3 was a NASA designation and the main public reference available has NASA contracting out P&W not Rocketdyne to perform a study of what the future of rocket engine development should be. Though its possible Rocketdyne also participated in some aspect of the study I've found no first hand source for that, we do know at the time they were doing a lot of aerospike and J2 nozzle studies. The timing of the study seems to be between the RL-20 and XLR-129. The study mostly concludes staged combustion is good and doesnt have any real designs associated with it but the RL-20 is a good analogue for that notional engine as like the HG-3 (as conceptualised) could be a drop in replacement for the J-2.

    I wrote down everything I found out here:

     

    On 2/3/2024 at 5:49 PM, Blufor878 said:

    That makes sense. In that case, what are the PL20 engines based on? Also are the XLR129 listed under a different name. I want to try this later.

    You can find more background on the RL-20 specifically in the link above too. The best reference online was Alternate wars but thats down now so I just have a few images and (maybe PDFs) saved from there lying around. But that post summarizes everything.

  8. On 1/21/2024 at 12:36 AM, dave1904 said:

    It's the earliest version I'm wondering about. I play with engine ignitor and live recreating rockets as realistic as possible in order to learn how they worked. I cannot find anything about the Thor and Vangaurd second stages. If they are pressure fed ullage would not be an issue right? If so I can just disable ullage and keep the ignition to 1? 

    I'm not entirely sure how it works. If I remember correctly the shuttle used rcs before it fired its aj10s but it might have been to protect the engine. 

    I'll need to double check on the staging, dont remember what sources I looked at for those configs. But pressure fed does not necessarily mean ullage is not required. Most pressure fed rocket stages for which I've found information show that they need ullage including the Apollo LM and CSM (seems like very small propulsion systems used on probes and satellites didn't).

    I do remember I found some specific information about a (version of?) Agena that included a sump tank for engine start that specifically ensured that it didn't need ullage and that's a pump fed stage.

  9. 20 hours ago, Thatguywholikesionengines said:

    There's no non-SAF version of the 3.125 -> 3.5m fairing base for Herakles/LDC. Love that fairing base and the included fairings, but some designs just need more complexity there. The Atlas V 5XX 2.5m to 3.5m adapter's fairing works just fine, so it's not a diameter issue. Hoping a customizable/non-SAF version of the big LDC fairing base gets added soon. :D

     

    https://imgur.com/a/rkToNDC

    This is just a config thing so can be done fairly easily. If someone could put this issue on github it will serve as a reminder when I can get to it.

  10. On 12/16/2023 at 3:30 AM, zakkpaz said:

     

    @CobaltWolf @Zorg there hasn't been an update or a progress report in awhile, did you guys move on to other projector or are you just taking a break?

     

    No judgement, I just feel like I might have missed some news, and I was really looking forward to the Atlas revamp.

    For me, something of a break for various reasons. I did post the finished LR101 model last month but that was the only progress I made in a few months. But hoping to get back to Atlas after the new year.

  11. On 9/16/2023 at 10:43 PM, septemberWaves said:

    What is this engine, and why is it wearing a jacket?

    To elaborate on what @Pappystein wrote, this was Pratt & Whitney's proposal for the SSME, competing with Aerojet's and Rocketdyne's (who won of course). It was derivative of their earlier work on the XLR-129 and in fact early on in the program when the thrust requirements were a lot lower, I believe the initial proposal was more or less an XLR129 and what we see here is a mockup of a later uprated and enlarged version.

    Throughout most of the program, P&W were considered the leading candidate as they had been working on staged combustion ideas long before the shuttle program, first through the RL20 concept and then the XLR129 which had components tested on the stand (for the ISINGLASS rocket powered boost glide spyplane). You will find a lot of the earlier Space Shuttle concepts from various contractors outright mentioning the XLR129 as the baseline engine.

    The thrust requirement from NASA kept rising though when it got to over 500k lbf, P&W were really struggling while Rocketdyne shot ahead to frontrunner by demonstrating an engine on the test stand at the required thrust level. However the chamber for this test was fed by fuel pressurized directly from the test stand and didnt have functional turbo pumps, I guess they thought they would figure out the turbo pumps later! Much to P&W's anger Rocketdyne won the contract despite their protests. As it turned out the early SSME was plagued by turbo pump issues which werent fully resolved until NASA hired P&W to fix the pumps :)

    Anyway its a strange tale of what might have been. The engine in the strictest sense isnt really within the scope of BDB. I suppose but I made the original XLR129 as part of series of oddball hydrolox engines as Cobalt had always wanted some of them in the mod (not the XLR specifically but M1 and RL20 were mentioned long ago). And since this is related and because I like It I might still do it someday.

    ps. more general comment re lack of Atlas updates, been a bit preoccupied but hopefully can resume work on it soon!

  12. 1 hour ago, Entr8899 said:

    Speaking of shuttles, @CobaltWolf@ZorgIs there any possibility you would consider making a Shuttle-style boattail with a sunken node for the XLR-129?

    Um no I dont think I have the time or motivation to do that. I *would* like to do the actual SSME candidate version which was a fair bit bigger and does have a boattail mount type thing. But not sure when (plus I dont have good refs as the layout is a bit different but its a maybe for someday).

    https://cdn.discordapp.com/attachments/690553577524953158/1150427551123132446/RG009_C01_F04_19670000_SSMEmockup.jpg

  13. 12 hours ago, zw_45 said:

    I think the mass should be reduced as well. The gross mass of Viking orbiter/lander is around 3.4T. Using 25% scale, it should be less than 1T, but now it’s much heavier if we consider the lander.

    We dont scale payload weight using the 25% rule. As a baseline we take the IRL mass (excluding prop mass) and then adjust as needed for performance.

    13 hours ago, OrbitalManeuvers said:

    Well, this will be interesting! Not sure what the minimal capture burn would be at the optimal transfer window, but with the current TWR at Mars, a 400m/s maneuver is a 20 minute burn. And we don't have lander mass yet, or the scaled down thrust ...

    We will take a close look at this sort of thing once the lander is available. But its not unknown for us to use IRL thrust or even overscaled thrust where necessary ( I think the peacekeeper Post boost vehicle has overscaled thrust, and I dont remember exactly but the LMAE and LMDE are I think somewhere between IRL and 25%).

    Anyway rest assured we will work to find a good balance between having an impression of the real thing and usability.

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