Zorg

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.

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.

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.

Its still on the cards. I was hoping to continue Rodger's work if he's not going to work on it further. But I've not had much time for modding lately and when I can resume I want to focus on finishing Atlas. So it will be a while I guess.

I made a mistake, I was just recalling some WIP CM IVA stuff Rodger had posted but it wasn't actually finished.

So this still needs a little tweaking in terms of the positioning of some of the bits but since I havent posted any progress in ages so here you go (yes Atlas is still happening and I am indeed alive). The shroud is a placeholder for the moment

Incredible!

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!

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).

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. 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.

Im gonna guess its Bella TU. It might not be up to date with the foil switch.

Hopefully at some point. Not sure when.

Thanks for that catch, fixed now.

Tbh I’ve never been a huge fan of the LSAM as it doesn’t have the fuel tank volume as a hydrolox spacecraft for what it’s supposed to do (which wouldn't work in BDB balancing). I think as far as FAM is concerned the original Jamestown module is very cool though.

Oh yeah sorry I ended up hallucinating that the CM Iva was made. Was just the historical LM

The historical CM and LM already have very nice new IVAs made by @Rodger. The upcoming new IVAs are ones very kindly modelled for us by freeIVA developer @JonnyOThan and cover pretty much all the remaining crewed parts that didnt have IVAs including a couple of MOL parts and all the skylab bits other than the main workshop (which was already done internally). Jonny isnt really into texturing though so I did the textures for most of these and added props to them. I just didnt have time yet to re-texture the IVAs for the advanced LM stuff like SHELab etc. So those parts have placeholder textures. I'll try to get to them soon, maybe when I need a break from Atlas which is proving to be a difficult project. New Skylab European Research module IVA New Skylab MDA iva. Theres plenty of others but these two are the most interesting probably. As usual once a new official release is out it will be pushed to CKAN, any new in development parts will then go into a development branch on github until they too are ready for an official release.

yup freeIVA configs and new IVAs will be in the 1.13 release. There are some LM derivatives that have basic placeholder IVA textures, they will be done properly at some point.

I dont think it detached. But invader can confirm.

Not sure myself. Compatibility for Realfuels is handled on the RealFuels Stockalike mod side. It doesnt look like its been updated since 2020. As Pappystein said, staged combustion = higher pressure = smaller engine for same thrust (plus more Isp). That said it is worth questioning the compactness of its turbo machinery a little. Every operational or near operational staged combustion cycle design I've looked at has boost pumps upstream of the main pumps (Including the RD170/180 family, SSME etc). Im not sure if the RL20 design, which was a very early concept of the staged cycle had such boost pumps. I guess it's possible its integrated together with the main pumps physically but the main high pressure fuel outlets being at the very top of the pumps suggest otherwise. Anyway theres not a lot of detailed information about the RL20. Ultimately the much closer to production XLR129 ended up with a larger more complex powerhead for similar specs.

I really don't intend to revisit those parts sorry.

The in game designation PL20-X3 is based on the RL-20 P3 design. It was Pratt & Whitney's early concept of a staged combustion cycle engine in the J2 thrust class. P&W were investigating the staged combustion cycle at a time when Rocketdyne was mostly interested in J2 nozzle improvements and aerospikes. Not much came of the RL20 design although it was seen in a handful of Saturn MLV documents as a future J2 replacement. Pratt & Whitney's staged combustion efforts evolved into the XLR-129 (which is also modelled in game) which went into component testing as it was developed for the ISINGLASS spyplane. Later the 129 was the basis for their SSME proposal and was the presumed leader throughout most of the competition until the thrust requirement went up and Rocketdyne won with their proposal. Thats a long story in and of itself. Anyway for the RL20, both sea level and vacuum optimised versions were looked at.

Thanks! Just wanted to note though that the previous one was modelled by PickledTripod and textured by Cobalt. It was a strange time when the US and Russia were quite cooperative and the US gov was interested in keeping Russian rocket engineers employed lest they go to less desirable destinations increasing proliferation risks. Plus the RD170 family (to which the RD180 belongs) remains to this day among the most performant sea level booster engines out there.

so the red ring there is an untextured placeholder (The ring is a toggle and will be part of the mount switches). But the texturing of the engine proper is just about complete apart from emissives. The text is also placeholder, exact wording and positioning could be different in the final one. For the bare engine there will also be a toggleable LOX pipe extension that will go up and and turn back inwards which should enable some kit bash options hopefully.

Yes this is for BDB1. The KSP2 situation being a bit more clear now (its not ready for BDB as we need a lot more functionality for BDB to work, either in the base game or through supporting mods), we have decided to continue with new projects for KSP1 in the meantime. Finding resources for engines can sometimes be hard, the other Atlas engines although overall simpler designs were more challenging to model as I had to go off of fewer pictures of complete engines and no orthographic schematics. The RD180 on the other hand is one of the most well documented engines. ps. yes I will be texturing the engine as well.

There is one bit of Atlas V (and Atlas III in particular) I am working on right now though