Reentry - A Space Flight Simulator News

Version 0.5 has been in development since the summer, and is going to be a great update for the Apollo program + some new things for Mercury and Gemini! With the release of version 0.45, I finally had the tools needed to get the Lunar module from the surface of the Moon back to the CSM.

You got a glimpse into what you can expect from version 0.5 in the previous post, but today we will take a look at other things 0.5 will introduce, and also talk about Atmospheric Entry for the Command Module. I will mostly use pictures do describe these features.

The initial plan was to release the lunar ascent, rendezvous and docking as one release, and then another release containing atmospheric entry for the Command Module. However, this has changed, 0.5 will have both Lunar ascent, rendezvous, docking and Atmospheric Entry. The bits are now in the hands of the Test Pilots!

Lunar ascent, rendezvous and docking
As most of the Lunar Ascent and rendezvous parts of this update was covered in my previous post, this post will cover the things that 0.5 will bring in addition to that. If you have not read the previous post, you can find it here:
https://steamcommunity.com/games/882140/announcements/detail/1709617390888004912

Atmospheric Entry
Apollo Atmospheric entry should now work again. There are many parts that needs more development cycles such as the EMS and procedures, and the autopilot during the entry programs (P60's), but at least it's now possible to perform an entry with the Command Module again!
The Atmospheric Entry Academy lesson has been remade to reflect the changes, and is now much better.

The EMS is a great tool during entry, and will show you the G load, distance left and suggested guidance. This is still in development, but it's enough to make you understand what it's capable of.


When drag increases you will now see a much more realistic plasma effect during entry.


Landing & Splashdown
When the blaze is over, you now enter a much better splashdown area. It's very important to arm the ELS system, or else you will crash. With the ELS system active, and set to AUTO, the apex, drogues and main chutes will deploy automatically. But verify this, and if a fault happens, you can deploy manually by setting the ELS to MANUAL, and use the altimeter to check when to trigger an action.


First thing you will see is the release of the APEX cover, shortly followed by the two drogues. The descent rate should slow down to about 200 ft/s or less, and the capsule should stabilize/hang from the two chutes. Do not use the RCS system at any time during landing, or the ropes will burn.


Then the three main chutes will deploy, and the descent rate should slow down to about 32 ft/s.


Followed by splashdown


Improves cockpit ambience
A new Cockpit Ambiance System is in the works, and will eventually roll out to all of the supported spacecrafts. This system generates a more true-to-life cockpit atmosphere with radio static noise, and the famous beep sound effect on radio messages. Lot's to be done, but feel free to give it a try.

Graphics & Performance settings
Render Probes
One of the major issues with Apollo is the amount of system resources it requires, and the amount of graphics used to render it all. The Earth, the Moon, the Saturn V stack with the CSM, and the Lunar Module, and both the virtual cockpits. That's a lot of draw calls. One of the biggest bottlenecks for performance is the reflection probes used to render reflections on materials. You now have an option to turn these off, or improve their quality.

Improved CSM Model
Small changes has been made to improve the quality of the Command Module and the Service Module.


Main Window Glare
The improved reflection probes can now render reflections on the main windows of a virtual cockpit. If you have a lit cockpit, the reflections will be more intense, while if you turn off all the lights, there won't be much to reflect at all.


Basic Crew Models for the CSM and LM
I'm working on a Crew Model and Astronaut Avatar system, used to create your own Astronaut. While this is in progress, I have enabled the option to render basic models of the crew in the CSM and the LM.



Off-screen Switch Indicator
Ease-of-use is very important for me, and TP SwGustav suggested adding a UI indicator pointing towards a switch when it's outside of your view. An off-screen switch indicator was introduced, and will be visible if a checklist or mission instruction needs you to change a switch not rendered. This will then point you in the direction you should turn the camera to find the switch.


All-in-all, with the introduction of Lunar Ascent, and Atmospheric Entry, version 0.5 will bring a lot on the table. Academy lessons has been added. In addition, a lot of issues has been fixed (and probably introduced too), thanks to all the bug reports and feature requests you have made.

Hi!
It has been a while since I posted anything here. The focus has been on getting the development of version 0.5x up-to-speed.

This post is a brief summary of some of the new features you will see in 0.5x, as well as some plans on the roadmap.

Version 0.5 has a focus on two major features for Apollo.
1) Lunar ascent, and CSM rendezvous and docking
2) Atmospheric Entry

The 0.5x update will be split into two releases where 1) will be part of 0.50 update, and 2) will be part of 0.55 update. Development has started on both, and 1) is getting close to a release for the Test Pilots.

In addition, 0.5x will have some other nice general features, fixes and a lot of general improvements.

Lunar Ascent & Rendezvous
For those familiar with the Lunar Ascent and the LM/CSM rendezvous will know that this is a complex operation. There are a lot of procedures involved, and many new systems will be used. In addition, you will need to control two spacecrafts at the same time. The LM during ascent, and the rendezvous burns, and the CSM for docking, and during the rendezvous burns.

The first part of the ascent is where the Lunar Module separates from the Descent Stage and uses it as a launch pad. The APS (Ascent Propulsion System) is used to take the Lunar Module ascent stage from the lunar surface into an elliptic orbit around the Moon, with the same inclination etc as the CSM. The CSM is in a larger circular orbit.


The initial orbit has and Ap altitude and Pe altitude of 17km x 83km. Once the LM reaches Ap, the orbit is circularized using a burn named Coelliptic Sequence Initiation (CSI). After this, an optional Constant Delta Height (CDH) burn and an optional Plane Change (PC) burn is used to align the LM orbit with the CSM orbit, as well as ensuring that the LM orbit is in a circular orbit 15 nm below the CSM circular orbit.

After the above burns, the LM is catching up with the CSM (it works in a similar manner as when the Gemini spacecraft is catching up with the Agena before the rendezvous burn). The Lunar Module is using the rendezvous radar to track the CSM, and have an attitude that where the LM is facing the CSM, and vice versa.


At the correct point in the orbit, where the line-of-sight (LOS) from the LM to the CSM and the flight path of the LM has an angle of 26 degrees, a relative motion burn takes place in the LOS direction. The LM is thrusting directly towards the CSM, and will now be on a rendezvous path. This burn is named the Terminal Phase Initiation (TPI), the burn to intercept CSM's orbit). A TPM (Terminal Phase Mid-course correction burn) takes place after this, followed by a series of small breaking burns named the Terminal Phase Final (TPF) - placing the LM in a similar orbit as the CSM.


All of these burns are planned using P32 and P3X, and executed manually using P41 and the RCS system.

There will be two methods of rendezvous in Reentry, one simplified and one advanced. The simplified method will still use P41 to execute the burns, but will use P30 to plan the burns, with parameters received from MCC. The simplifies rendezvous will have the CSI burn, and then a direct rendezvous hohmann burn, followed by rendezouvs and docking.

The advanced method will use P32 to plan the burns, and then P3X (one P3X for each burn like CSI, CDH, etc). The simplified method is now complete, and will be part of the initial release, while the advanced still needs some development and will be part of a later update.


New checklist system
The entire checklist system in Reentry has also been replaced by a new system. It looks similar to what you are used to but is now fully file-based. This means that each checklist has a dedicated file on your computer. A new checklist editor accessible using the in-game console can be used to add your own checklists, as well as modifying existing ones. When a mission is loaded, the checklist tabs of the Mission Pad will be procedurally generated based on the files it finds, and their data.

The checklist editor can also add Checklist Guidance Steps to it (if a checklist has one or more steps, the RUN button will be visible). A record feature will allow you to record the checklist steps that will execute when a player press RUN.

The DEFAULT checklists will be installed each time you run the simulator. It will detect if a default checklist is missing, and install it if so. If you have created modifications to a checklist, these modifications will persist. If you wish to reset it, just delete it and it will be installed the next time you start the simulator.

Each time you add a checklist, you will need to restart the mission for it to be visible. However, if you just make changes, the changes will be visible the next time you open the modified checklist using the mission pad.

Checklists can also have images (png).




The checklist system is applied across Reentry, meaning it is used in Mercury and Gemini as well as Apollo.

New Apollo Co-Pilot view
The new co-pilot screen allows you to give commands to your fellow crew members. You can ask the Lunar Module Pilot to guide you during the LM powered descent, or help you slew the rendezvous radar. Each of these features are tools and aids to simplify some tasks, and will used dedicated UI items. More features will be added.


For those who previously has done a powered descent has noticed that the LMP will start to tell you some important data, and that this data clutters the mission flow using the mission command UI. This has now been moved to a chat box bubble-like UI element, and can be enabled and disabled to your liking. All of the verbal aids from a co-pilot will appear in this view. Each update will not be a new message, but will replace the existing content, so it works more like a data view instead of individual messaged (like Verb 16 in the AGC/LGC)

Also, a RR slew aid has been implemented, where you get the shaft and trunnion angle changes needed to target the CSM.

I have not yet decided if this should use the UI above, or the same verbal chat box used by the co-pilot.

So, this brief update ended up being rather long, but I think this covers the major features you will see when 0.50 is released. 0.55 will have the new atmospheric entry model, and will be covered in a later post.

Thanks for reading!

Reentry has been in development for many years now, adding one spacecraft yearly. It all started with the Mercury capsule for the Technical Preview I release in 2016, followed up by the Gemini capsule in Technical Preview II in 2017. The Command Module was then added for the initial Early Access release in November 2018.

In 2019 we saw the addition of the Lunar Module, as well as many improvements to the simulator such as the new physics update introduced in 0.45, and the Lunar Landing with the Lunar Roving Vehicle introduced in version 0.4.

Version 0.5 is now in development, and will be the update where the last parts of a full Apollo mission will be introduced. This includes the Lunar Ascent, the LM/CSM rendezvous, returning to Earth and performing an Atmospheric Entry. These technologies will then be applied to the other space capsules in later patches, starting with Project Mercury in v.0.6.

2020 will be all about improving the simulator, enriching its contents with new missions, failures and systems. New play styles has also been in development and will start to see its light next year.

All in all, I think 2019 was a great year for the simulator, and I really look forward to seeing what we can do in 2020.

I wish to personally thank each and every one of you who has bought Reentry and supported the development, to those being part of the evolving Reentry Community, as well as for all the great feedback I have received from you. A special thanks goes out to all of the Test Pilots who has spent countless of hours in fragile builds, working through checklists and having control of partial spacecrafts in development, It's a lot of work, and the simulator would not have been the same without your flight hours.

The long awaited 0.45 (Early Access) update is finally out!

This update is the largest one written yet, as it impacts everything related to the physics in the simulator, so please keep this in mind as you play. The Test Pilots have worked a lot on testing the various parts of the simulator, and we have managed to fix most of the major and high priority issues we have found related to this update. However, that being said, there are still issues to be fixed, and I'm sure you will find things to report.

Please do so over at the official Reentry Discord channel at http://discord.gg/reentrygame

The physics parts of this update will most likely be invisible for most of the players, but is the basis for the work that will happen in version 0.5 and towards 1.0. It was required by the lunar ascent, as well as planning orbital maneuvers. As we move forward with the next updates and major updates, you will see the introduction of new tools and gameplay mechanics, balancing, as well a rendering improvements - all made possible thanks to the changes in 0.45.

Patch notes:
- Major physics update
- Apollo CM Tools (SPS burns, TLI)
- New Apollo Academy lessons for SPS burn planning and TLI
- Addition of a new Lunar Module Academy exam
- Console (open it in game using Back Quote)
- DevJournal (access it from the main menu or the console)
- First iteration of flight data profiling

Update 0.451.EA:
- timescale logging to identify who timescale is reset back to 1x in some missions
- LM exam panel state should now load C&D

Some major parts of this update still needs work, and going forward we will release minor patches correcting these things.
- Engines (F1, SPS, DPS ..) still needs re-balancing. Please expect longer ascent times, S-IVB and SPS burn times.
- TLI burn precision

The test pilots have been working hard on the latest version of Reentry, and a lot of fixes and changes has been made - big shout out to the Test Pilots!

I haven't really spoken much of what version 0.45 contains, other than that it's a rebase of the game, so in this post, I will try to explain some of the new things!

Physics
First of all, as you probably know, the physics of Reentry has had an upgrade. You will most likely not notice too much of this, but the general feel of the simulator should be smoother. The world size has increased a bit from the physics perspective, allowing me to start looking at the possibility to increase the world size further in future updates.

In addition, this allows for much more stable orbits; previously you would notice that your orbits apogee and perigee would flux and jump with an offset of multiple kilometers within even one orbit. Now, the orbit remains fully stable (with offsets limited to just a few fractions of a km). However, if you fire a thruster or an engine, the orbit will change, as expected!

This stability was really bad around the Moon. In fact, this was one of the major issues that needed to be fixed for me to write a proper Lunar Ascent Guidance algorithm. Lunar Orbits were almost impossible to work with and you had to request Ap and Pe from mission control to get accurate values. In this update, that button is gone, and the orbit is perfectly calculated in real time!

This has made it much easier for me to start writing tools that will execute much faster (remember the TLI and LOI calculations that could take a minute just to get a rather random value?). In 0.45, TLI and SPS maneuvers are planned using a new in-game tool!

Anyways, a lot of other changes has been made within the physical space, but let's keep it brief and move on to the tools!

Tools
Two new tools are added to the Apollo program (currently in experimental phase). Once complete, you can expect similar tools for Gemini and Mercury as well.

The first tools I wish to mention is the SPS Burn Maneuver tool. It's meant to be used by the Apollo CSM/SPS engine. A future update will allow you to select the Lunar Module DPS engine as the propulsion for the CSM (Just like in Apollo 13) as well.

The goal of the tool is to help you plan and execute burns to reach desired orbits. Currently this has not been possible except for eye-balling and manually burning.
Using the new tool, you can select at what point in the orbit you wish that the burn should be executed (in degrees, where 0 is at Pe and 180 is at Ap). Then you select how much delta V you wish to burn, and in what direction. An orange trajectory will then show you the estimated new orbit. In addition, the tool calculates when the burn should start (TIG), and for how long the burn will last. Keep in mind that all of these values are estimates, the actual orbit you will reach will differ based on how well you perform the burn.


Above you can see that I plan to execute a burn around Perigee, with a dV of 50 fps retrograde. The new orbit and burn parameters can be seen to the left, and a TIG icon will be rendered in the orbit view. The number of decimals will be reduced :D.


In the screenshot above, I plan a larger burn in prograde direction, at the orbital phase/true anomaly of 45 degrees from Pe. The orange trajectory shows the new orbit I will reach (again, estimate).


Lastly, I wish to highlight another feature of the tool. In this screenshot, you can see that the tool shows an Atmospheric Entry burn. This is all automatic. If the tool senses that you are planning a burn that will take you into the atmosphere, it automatically classifies this as an atmospheric entry burn/de-orbit. If this happens, it will show you where the entry interface starts and render an EI icon, as well as the entry angle at this point.

When you press REQUEST, mission control will get back to you with the burn data, as well as uploading this to the AGC so you simply can run P30 and P40 to execute the burn.

Let's move on to the next tool; the S-IVB Burn Planner. This tool will take you to the Moon. Previously TLI was calculated by requesting this from Mission Control. They would return to you with burn parameters what might take you to the Moon if you manually corrected the trajectory by eye balling.

This tool changes all that. TLI is now planned by you using some simple parameters. The tool will show you the estimated trajectory that will be recalculated as you change these parameters. This trajectory shows the path from Earth and at what Pe you will reach the Moon. In addition, it will also show you your Free Return trajectory, and at what Pe you will reach when returning to Earth.


Above you can see the tool. It shows you when the burn will happen, and and estimate of your new orbit. You will leave Earth following the blue line, and return following the orange line. A white line shows your trajectory around the Moon as seen below.


Once you reach the Moon, the SPS burn tool is used to calculate your LOI burn.


The tool will also let you know if you plan a path that will collide with the Moon.


Console
Another new feature is the in-game console. It aims at the advanced users and is meant to be used as a tool. It can be use to many tasks such as checking the game log, spaceship data (future), re-orientate the sun, monitor ascent data, check your orbital parameters, save the session state (and provide a file name!) and so on. I have just started working on this, so some programs will have more than others but this will evolve as we progress towards release.


The console is rather simple, and shows a large area for text, and one input field. You write your commands here and press ENTER to submit. By default, back quote is bound as the console button, but this can be re-mapped.

Above, I entered the command setsunphase 180. This moved the sun to a new position, a great tool while debugging or providing feedback.

A lot of commands are available, but much more will come.


Apollo ascent trajectory data
I have decided it's time to open up the simulator a bit more, and give you a glimpse into the details. The main reason is that I wish to create a better simulator, and creating algorithms that works equal on all hardware is a huge problem.
Given that, I have added another useful feature of the console: the possibility to export flight data. Currently, only Apollo Saturn V ascent and Lunar Module Powered Descent data is available but this will expand. The ascent trajectories in the sim are still rather coarse, but this data will be really valuable for me once I get to focus more on them. The data can be exported as either text or json.


This data can then be used in other tools and programs. A future update will also bring live and realtime graphs into the game so you can see this data nicely directly from the sim.


In addition, you can monitor this data live during your ascent.
To do this, you can use the monitor command:
mon -ascent



DevJournal
Another missing feature is the ability to talk to you directly inside the game. A news/DevJournal section is added to the main menu, but is also accessible from the in-game console in case you with to read the news while coasting towards the Moon, or Agena. This feature will keep you posted about news, major issues, fun stuff and so on.





Graphics improvements
Not a huge focus on graphics in this update but a lot have still be done. Shadows has received an overhaul, as well as some reflections and materials. Not too much to mention, but here are a few pictures to describe.


This sums up the new major features of 0.45.

Thanks again for your patience!
- Petri