Ultimate Steve's RO/RP-0 failures (and sometimes successes)!

[Ultimate Steve]

Welcome to my Realism Overhaul/Realistic Progression Zero mission report! This is not like my other ones, this one isn't a story, it's just me trying to space...

 

To make a long story short, I started playing RO/RP-0 about a year ago an a 1.1.3 installation, barely got to orbit, and got bored with it. A few months ago, I picked it back up and haven't been able to put it down since. I chronicled my misadventures in the "What did you do in KSP today" thread, but after a while I thought it would be better if it had its own thread.

So now I have to go and sum up 19 years of history in a short-ish introduction... Off we go!

 

Intro:

Spoiler

Before I started spamming screenshots, I did a bunch of sounding rockets and sent small satellites and eventually sent people into orbit. As I started sending probes to the moon I began using the screenshot key somewhat often.

Shown here is either Moonscraper 1 or 2, which were lunar impact probes... The first one failed due to improperly configured RCS if I recall correctly (most of my failures are due to that issue).

Shown above is Sailor 2, the first ever probe to soft land on the moon in my game. A total of 6 (I think, might have been 7) Sailors were launched, with 2, 4, 5, and 6 being successful.

After that I decided I needed a bigger launch vehicle.

Until that point, I was using Mu III, which is shown in the middle. It could only take about 10 tons to orbit at best.

So I built Gravity I.

Shown far left. At the time it could take 30 tons into Low Earth Orbit. I used it to launch people around the moon in modified Mercury capsules.

After several near misses (including a circumlunar rescue mission) this was retired because the program had accomplished all of its goals and I built a few Salyut style space stations, Sapphire and Ruby.

Then I decided to send people to land on the moon. In order to do this I designed Gravity III, heavier than a Saturn V but with less capability.

The first one was the ugliest rocket I'd ever built. In the first two test flights I learned a ton. I have a sticky note sitting around somewhere with about twenty design changes I needed to make.

Around then I discovered visual mods and I started paying more attention to aesthetics.

And then, either in 1963 or 65, I landed Jebediah on the moon.

I then did two more lunar landing missions. All three of them nearly ended in disaster. The first one didn't have enough oxygen, the second one flipped out of control due to the off-center oxygen container, and the third one almost ran out of fuel.

At this point I decided I'd take a break of 5-7 years to research better technology (with KCT I had years worth of science points to spend) and I would, in that time, launch space probes, build a LEO station, and a LLO station.

Fast forward to 1970, we have:

AVALON STATION!

About 75% of the mass of the ISS and 400-500 parts. Docking is a real pain, which is why I have limited myself to crew launches every 180 days. It is composed of 18 modules, 2 life support containers, an RCS tug (that never got used), and 1 or 2 crew ships depending on the time of year.

Its primary mission is to look cool. Its secondary mission is to get science (although I accidentally sent up 1 scientist instead of 2 on the last flight so its been dormant for the last 4 months).

However, it accomplishes its primary mission very well, if I do say so myself.

 

Also, ECLIPSE STATION:

This was built to be launched in 7 modules on board the last Gravity III's. Shown here are the first 5 modules with the Yonder 1 spacecraft attached on the end.

And I have launched a Venus orbiter/lander combo (the lander did not work) as well as a few Mars probes. One orbiter did not have enough fuel. Another time I reused a transfer stage as a Mars impactor... I have flown by Mercury as well.

And, finally, I have launched probes to Jupiter and Saturn, although they will not make it there for 2 and 3 years respectively.

 

Launch Vehicles:

Spoiler

From left to right, we have Mu 0, the thing that launched the first satellite (which I accidentally destroyed because I wondered what the "range safety" button did), Mu I, which sent the first people into orbit, Mu II, which was a failed bigger version of Mu I. It had one flight which almost ended in disaster. Fortunately, Valentina Kerman survived and I started putting LES's on manned ships (about half the time - yes, I know). Mu III was my workhorse for a long time but suffered from low capacity and relatively high part count. After several upgrades it wasn't even the same rocket and eventually I moved on to Mu IV, which was better but had serious spaghetti problems. If you didn't fly straight up until 20km, it would flip and explode. Mu V is my new medium workhorse and so far it has only failed once in about 8 flights. It can take 20 tons to LEO.

The Neutron series is used when I need small and tiny payloads lifted into orbit. Neutron I was a failure on all three launches for various reasons and I didn't like the look so I redesigned it into the Neutron II which was mostly successful. Some re-proportioning later, we have the more efficient Neutron III which can take about 3 tons into LEO.

Neutrino is for when I need 500kg payloads, which is not very often.

The Gravity series are for when I need big things in orbit. Gravity I, IA, and IB are all basically the same with upgrades and can take 63T to LEO max. Gravity II is functionally retired as it is pretty much useless. It only had 2 flights and can only take 10t to LEO. Gravity III is my super heavy moon rocket but it is outdated and only has one more flight scheduled. It can take 30t into LLO. It will be replaced by Gravity V which I haven't designed yet. Gravity IV is a large version of Gravity I with a hydrolox core designed to launch massive interplanetary probes. It has currently flown four times with a fifth one under construction to launch a probe to either Uranus or Neptune.

On the left we have the first vehicles to put people in space. Yes, I just strapped a cockpit and parachutes to a V-2 rocket... Spoicey Joe was designed to test the LES for the Spoice program (my manned lunar program). Kappa only flew once and did not work. Its purpose was to deliver tiny 200kg resupply packages to Avalon station and be ready to do so at a day's notice. No need arose for it to ever be used. Melody is my LEO crew ship similar to Soyuz. It can take 3 people into LEO, although it will be quite cramped. Sigma was launched 4 times, IIRC, twice to Sapphire station (for no good reason except to prove I could dock), one failure, and one artificial gravity tether experiment (which got to 0.008 or so g before the tether snapped). Illectro was a good idea but it proved to be too expensive to use regularly. It was designed to be a 3 man crew transfer vessel which could also carry KAS/KIS cargo. However, the spacecraft ended up at about 30 tons and needed a huge rocket. While it was useful for removing RCS ports, it has most likely seen its last launch as it is pretty expensive for what it does.

These aren't really important, although SMALL-2 can theoretically reach orbit and only weighs about a ton.

A sense of scale:

 

 

 

 

Future plans:

As far as the near term goes, I'm going to finish Eclipse station and do a few more manned moon landings. In the medium term, I'm going to do a test launch of Gravity V (200-300t to LEO) and begin building a small outpost on the moon. Long term, my goals are to build a NERVA mothership and send people to orbit Venus and walk on Mars by 1980.

 

Updates will be in posts. I did a lot this week, and I was going to write it tonight but the OP took really long so I may not get to writing it until tomorrow.

 

Thank you for your time, enjoy my failures (and sometimes successes)!

[Ultimate Steve]

Update 1 - 10/22/17

So, what has happened? Well, I sent three ships to Mars.

This is the Mars Communication Network, for all intents and purposes identical to the one I sent to Venus. The other two are a ten ton propulsive lander and an 0.5 ton parachute/tiny engine lander.

Next up, something big:

This lander, the Tranquility, was a lander sent up to Eclipse Station on a Gravity IB. It is powered by 6 radioisotope rockets (technically they are a non RO part but they are at least somewhat realistic) and designed to be reusable. It departs from the station carrying Jebediah Kerman and Stanislav Vetochkin (bet you five bucks I spelled that wrong).

Now, let me back up a bit. Eclipse station was only supposed to be crewed after it was completed, but due to a bug I needed to crew one of the modules in order to be able to control it (RT did not want to work that day). However, because I had Yonder 1 docked, I could send them and have a way to get them home. Unfortunately, Yonder 1 was meant to be a test flight. However, the logic was that it was a repurposed Melody spacecraft that had flown several times already, what could go wrong?

Anyways, the fact that I had crew on the station meant that I could now land people on the moon for the first time in 4-5 years or so. Again, the lander was only a test, so I was jumping the gun here, but my IRL time is valuable, so why not?

Unfortunately the lander had a TWR of about 1.1 on the moon, so landing was difficult.

Fortunately, I made it, although I landed at 30m/s and blew up the KIS containers (there was nothing in them anyway and I didn't have an engineer). I also had much lower fuel margin that I expected due to the low TWR, but it was a workable margin.

Also, flags! Yay! I didn't have flags at the time of my first three lunar landings, so Stanislav becomes the first person to stab another celestial body (and Jeb becomes the first person to go to the Moon twice).

You're probably wondering why I landed at night. There's a reason for this.

You will notice that there is no science equipment on the lander. The idea was that after the test flight I'd put them in the KIS containers and deploy them once on the surface, but because my first test flight had turned into an operational flight, I decided I wanted to get some science out of it.

So, I landed 2.1km from Sailor 5, the third probe to land on the Moon. Not bad for my first attempt at precision landing in RO! I then used the scientist to run the experiments and collect the data.

Stanislav and Jeb set the duration record for time on the Moon at a week or two compared with the 2 minutes, few hours, and couple days of the previous 3 missions.

They returned safely to Eclipse station and began processing the data in the lab. Once processed, this data will yield a few thousand science points.

Then, I launched a spy satellite on a Mu V.

My goal was to turn Earth into a Death Star, but due to faulty RCS (I keep making that stupid mistake) this was as close as I got.

I then launched another ScanSat on a Neutron III to perform a biome scan. This too was plagued by RCS problems but was placed into a lower orbit than planned as a result.

*DING*

Yes! My Venus fleet is finally at Venus!

This is my Venus comms network, and that is Venus, although you can't tell due to the shadow.

Burning into orbit. I was 200m/s short so each of the four satellites had to complete the insertion manually.

Unfortunately, due to complete lack of fuel, these four relay satellites were placed into vastly differing orbits rather than an equally spaced low orbit system that had been planned.

Planetoid 10 entering Venus orbit. This is my scientific Venus lander.

Now at this point I realized my comm network was pretty much useless because I overestimated my fuel capacity and the power of omnidirectional antennas.

In the Earth system you can use omnis out to the Moon. However, at Venus there are no ground stations.

And if omnis don't work, you need one antenna pointed at Earth and the other at the ship you want to talk to. However, all of the relay satellites only had one powerful antenna. And the lander probe had one medium strength one. The actual lander only had an omnidirectional antenna, which I thought would be enough to talk to the relays. Nope.

I had forgotten to deploy the main antenna on the orbiter portion of the lander. So I had to wait until two of the relays were close enough to use the omnis and turn one of their antennas to the lander keeping the other one at Earth.

After that was sorted out, I set out to land on Venus.

The entry went well, however I did not have a signal connection so I could not deploy the gear, the parachute, the experiments, or even jettison the heat shield.

Slightly immature comment, but it sort of felt like I was flying through farts...

Wait, it survived? Cool! I mean, I was going only 30m/s, so it was a possibility.

Unfortunately, I had no proof to the contractors of the first successful landing on another planet. The communication signal was cut off, and the probe was rolling downhill. However, I set up my crippled relay constellation in a way that the signal went from Earth to one relay to the elliptically orbiting lander orbiter which then traveled via Omni to the lander...

Unfortunately, this connection only lasts 3 minutes per orbital pass. And, signal delay is basically 3 minutes as well, giving me about ten seconds of time when I can actually do something useful.

The first thing I did was deploy the gear in order to stop the spinning, then I did science. On the next orbital pass, I transmitted the science.

Yay, mission success! Almost! The Venus comm network was supposed to be a framework for future landers and it was completely broken... I'll need to send a second one (but I'm basically broke at this point so I'll have to wait a bit).

Also, more bad news. I sent the exact same system to Mars.

*FACEPALM*

Back at Eclipse Station, I sent Bob, Jeb, and Stanislav home because they'd been on the station for several months already.

Entry went flawlessly, the test flight of Yonder being successful. Now the docking port was free...

This is probably the second to last Gravity III ever to launch. It carries module six of Eclipse Station, the docking module.

It got to the station correctly but I forgot to take screenshots...

Anyways, for a "map" of Eclipse Station...

On the bottom, we have the Hadfield Utility Module, named after Chris Hadfield (awesome guy) and designed to hold electric charge, life support, fuel, and be able to reboost/move the station if necessary (in retrospect I really should have put the station in a polar orbit). Above that is the Numa habitation module (because I was listening to that Numa Numa Yay song at the time) designed to provide power and living accommodations.

Above that is the Earthrise Cupola Module, which is a node and observatory platform. On the right is the Modulin Science Module, which is a science lab, designated airlock, and life support container (with around 5 man-years of supplies). On the left is the Sergeant Utility Module, which has solar panels (not deployed in the picture, that's just a tug), more living space, a KIS container, and a tank of fuel for Tranquility. The solar panels on the module are part of the space tug which has since been de-orbited. On the very top is Yonder 1 which is not there anymore and has been replaced by the North Star docking module. Sticking up from the center node I will place a command stem which will also carry cool lights.

 

What color do y'all think would look nice?

 

-Steve.

[Kerbalstar]

@Ultimate Steve This looks very cool. Also for the lights I would go with blue and green.

[IncongruousGoat]

Wait... how in the anything did you manage to land on Venus? My attempts in 1.2.2 RSS/RO/RP-0 have ended with the lander being destroyed by pressure while still ~20 km up from the surface.

[Ultimate Steve]

4 minutes ago, IncongruousGoat said:

Wait... how in the anything did you manage to land on Venus? My attempts in 1.2.2 RSS/RO/RP-0 have ended with the lander being destroyed by pressure while still ~20 km up from the surface.

Probably because I'm in 1.1.3. Not the most realistic thing ever. But, if we're talking realism, I could have built a pressure resistant lander like Venera. However, I don't know of any Venera mod, so this will have to do.

[Ultimate Steve]

Okay, sorry this took so long, but...

Update 2- 12/26/17

I got a supercomputer for Christmas! Okay, not a supercomputer, but a really nice built-for-gaming computer that absolutely blows away the laptops I'd been playing with previously.

I had stopped updating this because it got too unbearable on the laptop. Too many mods, visual enhancements, and 400 part Avalon Station.

But now Avalon Station is at a playable framerate! Yay!

 

So, a long time ago I came up with an acronym - "Futuristic Advanced Large Landable Spaceship" or FALLS. And it would launch on a Gravity IB booster - so "Gravity-FALLS." Hehehe.

This is just a simulation. Unfortunately it's having trouble reaching orbit and it will not survive re-entry, so we may never see an actual flight, but, hey! It gave me a cool screenshot, so it was worth it!

It's basically "What if the space shuttle launched on a bigger version of Falcon Heavy."

 

 

I undocked the Skye 3 capsule from Avalon Station and brought the astronauts back home.

It landed in Africa near the Canary Islands if I remember my geography well enough.

Then I launched Melody 6, which carried Stanislav, Teresa, and Victoria to Avalon Station. It was supposed to be Regina instead of Stanislav but he somehow snuck aboard.

I'm actually getting flashing yellow-green timer! That's just so fast considering that this is RO/RP-0 with visual mods!

Second stage burn.

Burning the service module stage, and...

At the station (the far end, next to the small inflatable module, not that you know what that is).

That's all I've done today so far, but I began work on designing a small moon outpost. I designed a rover, but for some reason those rover wheels aren't working. Better wait until I unlock the "real" ones!

 

Does anyone know what year the RP-0 clock starts on? The time changer mod isn't working for me.

 

[Geschosskopf]

13 hours ago, Ultimate Steve said:

his is just a simulation. Unfortunately it's having trouble reaching orbit and it will not survive re-entry, so we may never see an actual flight, but, hey! It gave me a cool screenshot, so it was worth it!

Yeah, definitely worth it.  You should posterize it.  NASA's walls are covered with posters of things hypothetical / conjectural things.  This would fit right in  

Congrats on the new gaming rig, too!

[Ultimate Steve]

Update 3 - 12/27/17

Spoiler

Today was a big day!

First off, a Gravity IB launched the first module of Pioneer Base - my first attempt at a (very small) Moon base!

Fairing separation. The base has room for 5 with a medium amount of life support.

Circulatization around the Moon. However, unfortunately we are 300m/s short of what is required to actually land, so the base is stuck in LLO for a while. We were originally going to unlock the KLAW and refuel it with a Mu V mission, but I decided that would be too unrealistic and I would try to refuel it with KAS/KIS on Yonder 2, the next mission to Eclipse Station.

*DING*

What was that, I wonder?

A 10x budget increase! YEEEEEEEEEEEEEEEEEEEEEEEEEESSSSSSSSSSSSSSSSS!!!!!!!!!!!!!!!!!!!!!!!

The crew aboard Emerald Station have been in space for a year and have given us over 7 million funds! The station is designed with artificial gravity in mind. So now we need to return them to Earth! The last of the second run of Melody spacecraft (Melody 3-7) was launched to return the crew.

Unfortunately, due to a computer error, the rocket's angle of attack exceeded design specifications and it exploded. The crew would have been fine thanks to the LES, though.

So we built the third series of Melody vessels, 8-11. The major changes were larger forward RCS tanks and larger solar panels.

Melody 8 successfully docked to Emerald station and returned the crew to Earth.

So, now we have 7 million funds. With this I would like to accomplish several goals.

1. Manned Mars Landing. Self Explanitory.

2. Moon outpost with a rover and science laboratory.

3. Reusable LEO crew ferry which can carry at least 6 crewmembers there and back.

4. LEO-LLO crew ferry for use in space. To be refueled after every mission. To transfer crew from LEO to LLO.

5. Probe all the planets!

 

As far as goal 1 is concerned, we will need a big rocket (I'll get to that a bit later). I started work on goal 2, which might get switched to a larger rocket or the conceptual Gravity IC (upgraded once again). Goal 3 was supposed to utilize Gravity-FALLS but that didn't work out so well. Maybe a smaller version or something else entirely. No progress has been made on goal 4. And as for goal 5, we've already probed Venus, Mercury, and Mars, with probes on the way to Saturn and Jupiter. We have built a Uranus probe but the transfer window isn't for a few more months.

Next up we launched the Lunar IMaging Orbiter, or LIMO. Its goal is to complete a multispectral scan of the Moon. However, it was mostly just an excuse to use the Mu V again. It's a nice rocket to fly.

Fairing and booster separation. The second stage was going to be used for TLI but unfortunately it failed to start at stage separation. The restart worked, but that meant we were out of restarts.

However, it eventually managed to make it into LLO after a slightly complex maneuver that I don't really want to type out here.

 

Earlier I mentioned "Manned Mars Landing" and "Huge Rocket." Well, I present... GRAVITY V!

It is powered by the N1 engine block on the first stage, thirteen J-2 engines on the second stage, and three J-2 aerospikes on the third stage. It also has eight Titan IV SRB's and will be the rocket to construct an orbital Martian mothership.

 

Shown here is the launch of Test Flight 1. It took around 100 days to build, so it will be used sparingly, and is rather expensive, at a quarter of a million funds, actually netting a higher cost per kilogram than Gravity IB, but I think I'm going to try and shuffle up the configurations a little bit to lower the cost. Not sure how easy that will be, but we'll see!

Unfortunately I hit the launch tower upon liftoff and one of the SRB's exploded.

However, the gimbals were able to compensate for the loss of thrust.

Thirteen J-2 engines on the second stage fire.

However, the third stage proved to be nearly uncontrollable without gimbal. The RCS was just too weak to do anything and the stage slipped sideways. However, using up one of the restarts, I was able to get the payload into orbit.

The third stage then flipped around and de-orbited before releasing the payload (in order to minimize debris).

The mass of the payload? Just over 300 tons. MUAHAHAHAHA! I have now surpassed real world lift capacity!

 

 

Comparison to the rest of the Gravity Family. Easily the tallest rocket yet, at 85 meters. Unfortunately it looks a bit more "Missile" than "Rocket" But I'm thinking that's just due to the length of the fairing. Also, those are 12 meter tanks, and that's a 9 meter faring!

More relevant comparison:

It's not the tallest rocket by a long shot compared to IRL rockets. However, it is the widest as well as the highest capacity. Gravity V has a 300 ton capacity whereas the Saturn V had around 120.

 

MUAHAHAHAHAHA! I'm coming for you, Mars!

 

EDIT: I can get the cost down to around 175k if I try. The SRB's alone cost 75k, LFB's would probably be cheaper.

EDIT2: The aerospikes are 9k each and the normal J2 engines are "only" 2k each, so there's 21k in savings right there. The J-2's also have gimbal, so there's that problem solved. The only downside is reduced efficiency, but it's really only losing 20 or so points of isp, so not that big of a performance hit (also I was using the wrong J2 config so now I have more thrust which should make up for that).

 

 

 

Edited December 28, 2017 by Ultimate Steve

[DAL59]

55 minutes ago, Ultimate Steve said:

Gravity V has a 300 ton capacity whereas the Saturn V had around 120.

 

MUAHAHAHAHAHA! I'm coming for you, Mars!

How many launches for your Mars mission?  Will you use ISRU?  Preposition a habitat or ascent vehicle? Or assemble something in LEO?

[Ultimate Steve]

39 minutes ago, DAL59 said:

How many launches for your Mars mission?  Will you use ISRU?  Preposition a habitat or ascent vehicle? Or assemble something in LEO?

To be honest I have not determined anything about the mission besides the facts that it will be assembled in LEO, the mothership will be named Andreas, and the lander will be named Monroe. I have not unlocked ISRU (If RO/RP-0 even has those), so that's out of the question... I haven't even unlocked rover wheels yet! Although, I'm researching them now. An ascent vehicle might be prepositioned, it would probably be a good idea considering I haven't even landed anything successfully on Mars yet (although I have two probes en route).

[Geschosskopf]

2 hours ago, Ultimate Steve said:

However, the third stage proved to be nearly uncontrollable without gimbal. The RCS was just too weak to do anything and the stage slipped sideways. However, using up one of the restarts, I was able to get the payload into orbit.

I've never understood why KSP aerospikes lack gimbal.  Aerospikes are composed of many small combustion chambers surrounding (for the circular kind) or running down the length of (for the linear kind) the central "spike" part.  Each combustion chamber should be capable of being throttled independently.  Hence, you get different amounts of thrust on 1 side of the central axis or the other.  Same effect as gimbal., even though the whole not-a-nozzle doesn't move.  So I wouldn't consider it cheating at all to use MM to add gimbal to aerospikes.

 

2 hours ago, Ultimate Steve said:

It's not the tallest rocket by a long shot compared to IRL rockets. However, it is the widest as well as the highest capacity. Gravity V has a 300 ton capacity whereas the Saturn V had around 120.

MUAHAHAHAHAHA! I'm coming for you, Mars!

Way to poke reality in the eye.

[IncongruousGoat]

My recommendation for lowering the cost of the Gravity V is twofold. First, ditch the aerospike J-2's in favor of the S model of the J-2. TWR/Isp differences between the two are negligible in vacuum, and the S has gimbal and costs around a quarter as much. Second, don't use UA-1027's. They're kinda expensive compared to liquid alternatives. My recommendation would be some sort of F-1 based booster/sustainer arrangement, although you may want to grab SSTU if you go that path-the F-1 model that provides has a much lower base footprint and thus clusters much better.

2 minutes ago, Geschosskopf said:

I've never understood why KSP aerospikes lack gimbal.  Aerospikes are composed of many small combustion chambers surrounding (for the circular kind) or running down the length of (for the linear kind) the central "spike" part.  Each combustion chamber should be capable of being throttled independently.  Hence, you get different amounts of thrust on 1 side of the central axis or the other.  Same effect as gimbal., even though the whole not-a-nozzle doesn't move.  So I wouldn't consider it cheating at all to use MM to add gimbal to aerospikes.

Who said anything about throttling? Most real engines can't throttle, and I can't see why the chambers used in a toroidal aerospike (especially a toroidal aerospike derived from the J-2 powerhead) would be any different. Plus, that kind of differential throttling would be super hairy from a plumbing perspective, especially if (as is implied for this engine) the chambers are running off of a common turbopump assembly.

[Ultimate Steve]

4 minutes ago, IncongruousGoat said:

My recommendation for lowering the cost of the Gravity V is twofold. First, ditch the aerospike J-2's in favor of the S model of the J-2. TWR/Isp differences between the two are negligible in vacuum, and the S has gimbal and costs around a quarter as much. Second, don't use UA-1027's. They're kinda expensive compared to liquid alternatives. My recommendation would be some sort of F-1 based booster/sustainer arrangement, although you may want to grab SSTU if you go that path-the F-1 model that provides has a much lower base footprint and thus clusters much better.

Great minds think alike! I'd already come to the first two conclusions. The aerospikes are now J-2's and the SRB's are now LFB's. The LFB's are now (I think) derived from the engines on the first stage of Proton, with three engines per booster.

[Geschosskopf]

26 minutes ago, IncongruousGoat said:

Who said anything about throttling? Most real engines can't throttle, and I can't see why the chambers used in a toroidal aerospike (especially a toroidal aerospike derived from the J-2 powerhead) would be any different. Plus, that kind of differential throttling would be super hairy from a plumbing perspective, especially if (as is implied for this engine) the chambers are running off of a common turbopump assembly.

If LFO engines can't throttle, why have them at all?  What happened to "Challenger, go with throttle up" ?

I do agree, however, that running all chambers off a common pump is stupid.  So you wouldn't do that.  Instead, you'd have 4 separate, independent systems, each essentially a separate engine, like in a cluster.  After all, the individual chambers don't care how many chambers there are, they only care about having the spike on 1 side of them.  So, by turning these systems on and off (or throttling them somewhere between), you could get pitch and yaw "gimbal".  So for a toroidal aerospike, imagine the ring of chambers as 4 pizza slices.  Or you could make a "square" aerospoke, essentially 2 linear ones at right angles and superimposed.  Each side of the square, or each pizza slice, would be plumbed and throttled independently of the others.

Or, you could just use 2 systems, say for each side of a linear aerospike.  Then RCS and/or torque rolls the rocket as needed so this 1 means of "gimbal" can do both pitch and yaw as needed.

Edited December 28, 2017 by Geschosskopf

[IncongruousGoat]

2 hours ago, Geschosskopf said:

If LFO engines can't throttle, why have them at all?  What happened to "Challenger, go with throttle up" ?

I do agree, however, that running all chambers off a common pump is stupid.  So you wouldn't do that.  Instead, you'd have 4 separate, independent systems, each essentially a separate engine, like in a cluster.  After all, the individual chambers don't care how many chambers there are, they only care about having the spike on 1 side of them.  So, by turning these systems on and off (or throttling them somewhere between), you could get pitch and yaw "gimbal".  So for a toroidal aerospike, imagine the ring of chambers as 4 pizza slices.  Or you could make a "square" aerospoke, essentially 2 linear ones at right angles and superimposed.  Each side of the square, or each pizza slice, would be plumbed and throttled independently of the others.

Or, you could just use 2 systems, say for each side of a linear aerospike.  Then RCS and/or torque rolls the rocket as needed so this 1 means of "gimbal" can do both pitch and yaw as needed.

Liquid engines can be shut down and restarted, and generally have higher specific impulses than solid engines and, in many cases, are easier to work with. Some engines, including the SSME, have a limited throttling capability. Most, however, can't throttle, especially older engines from the 60's and 70's, such as the ones being considered here (this is RP-0, after all).

You could use 4 separate turbopumps for the engine... but then you have to design an all-new powerhead, throwing out all the work you already have done on the J-2 powerhead, and you more or less quadruple your number of potential failure points in the process. If they were designed with throttling in mind (which isn't a given) you might be able to make that work, but turning them off and on again definitely will not do what you intend. Turbopumps don't start up immediately, and typically can only be started a limited number of times due to any number of possible technical reasons.

Having only one axis of control wouldn't work great either. Reaction wheels are out of the question as a control mechanism-in RO, they're a means of rotating space stations over the course of several minutes, not a means of rotating a rocket in a couple of seconds. RCS wouldn't be too good either-the required amount would cut pretty seriously into payload capacity.

[Geschosskopf]

11 hours ago, IncongruousGoat said:

Liquid engines can be shut down and restarted, and generally have higher specific impulses than solid engines and, in many cases, are easier to work with. Some engines, including the SSME, have a limited throttling capability. Most, however, can't throttle, especially older engines from the 60's and 70's, such as the ones being considered here (this is RP-0, after all).

The SSME dates from the early 70s at least so no problem there.

 

Quote

You could use 4 separate turbopumps for the engine... but then you have to design an all-new powerhead, throwing out all the work you already have done on the J-2 powerhead, and you more or less quadruple your number of potential failure points in the process. If they were designed with throttling in mind (which isn't a given) you might be able to make that work, but turning them off and on again definitely will not do what you intend. Turbopumps don't start up immediately, and typically can only be started a limited number of times due to any number of possible technical reasons.

Well, considering that as of 2017, not a single aerospike has flown AFAIK, and that the few built (at least until very recently) were just bench test models to see if the underlying concept actually worked, I figure that if anybody was actually going to build one for flight, it would be a de novo design anyway.  Given the desirability of steering with it, I'm sure this would be part of the new design.

An aerospike, despite being only 1 piece in KSP, is actually an engine cluster.  Its plumbing thus already has a fairly high level of complexity; dividing this into quarters doesn't add much more.  And you have 2 options for throttle/gimbal.  #1 is to use whatever method the SSME had.  The other is physical gimbal using a common powerhead.  Because the aerospike is a cluster, there's no requirement that all its nozzles be centrally located.  Imagine splitting a linear aerospike down the middle and mounting each side of it on opposite sides of the rocket core.  Do this twice so you have 4 lines of combustion chambers forming a square when viewed down the length of the rocket.  This gives them more leverage for steering.  Then either throttle each side independently SSME-style, OR use a common feed and physically gimbal each side of the square.  Given that all the chambers on one side are in a straight line, you'd only need 1 hinge for all them.  Each side only needs to move in 1 direction, too, so the gimbal mechanism would be fairly simple mechanically per side.

So basically, I don't see any major problem in providing "gimbal" to aerospikes.  I'm sure that, when/if aerospikes actually start flying, especially as the main engines for SSTO rockets, they'll have steering one way or another.  And if aerospikes had actually become a thing back in the day, it seems to me that steering them would have been quite possible once the engines moved from test articles to actual flight models.

 

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Having only one axis of control wouldn't work great either. Reaction wheels are out of the question as a control mechanism-in RO, they're a means of rotating space stations over the course of several minutes, not a means of rotating a rocket in a couple of seconds. RCS wouldn't be too good either-the required amount would cut pretty seriously into payload capacity.

OK, all the more reason for being able to steer aerospikes

 

Edited December 28, 2017 by Geschosskopf

[Ultimate Steve]

I played a bit today, I don't have pictures, but Yonder 2 (new crew, lander upgrades, refueling the base so it can land) is en route to the moon and running a bit low on fuel.

The second Gravity V is being built, it features liquid boosters, better interstages, and no more aerospikes. Its payload will be the Firework 1, a probe designed to get as close to the sun as possible without gravity assists. It has about 25km/s of delta-V, not bad considering the size of the payload. It will be the first test of a NERVA, which will be a crucial part of the upcoming Mars mission.

I'm also sending an impactor to the Jupiter system in about 50 ingame days on a Mu V should all go well. The next launch overall will be a Uranus orbiter, on a Gravity IV.

EDIT: I have determined that the Lunar Station is big enough and the final module has been cancelled in favor of using the "last" Gravity III for something else, and maybe someday launching future modules on Gravity V. If I do need a docking module it can be delivered using Gravity IB, it should be light enough.

Edited February 16, 2018 by Ultimate Steve

[SiriusRocketry]

@Ultimate Steve this thing still alive?

[Ultimate Steve]

8 hours ago, SiriusRocketry said:

@Ultimate Steve this thing still alive?

On and off. I just got back from a 3 week trip and in a few days I go on a 1 week trip. Then band camp starts, then school starts, so RIP my free time.

Balancing my interests and several other mission reports (not to mention IRL stuff) can get tricky, so I sort of bounce back and forth between them. I did do some stuff in this before I left, but it wasn't much. This isn't dead, just dormant.

[Ultimate Steve]

Oh, also @SiriusRocketry if you can't wait for this, there's Space Race, a Realism Overhaul Space Race between me, qzgy, and NSEP although NSEP has unfortunately dropped out, if you want to see more RO stuff.

Edited July 23, 2018 by Ultimate Steve