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[1.8.1-1.11.2] Bluedog Design Bureau - Stockalike Saturn, Apollo, and more! (v1.7.3 "Огромный" 19/Apr/2021)


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10 minutes ago, RyGuy_McFly said:

So the fact that the only Belle fuel tanks that show up for me under "Fuel Tanks" in simple mode in the VAB are the Belle-120A and the Belle-240BD (along with many, many other parts) is definitely a bug then?

Correct. Notice in that screenshot I have the 0.935m cross-section tab selected, using advanced mode.

In response to the first - no, that is correct. There are fewer Belle tanks than before but I think the mod has more 0.9375m tanks as a whole now. Not every part received a 1:1 replacement in the update, for a variety of reasons. In this case I think it was simply that there were only two historical tank lengths. The new parts don't automatically replace the old ones (since we had to leave the old ones in to not break old crafts). You need to rebuild the crafts using only the new parts.

By viewing in the "advanced" mode (is that what the other sorting methods are called? I've never really used them), you've exposed something that we were unaware of - the old deprecated / hidden parts are still showing up there. They shouldn't be used and any crafts using them should be replaced if possible, since those parts will eventually be deleted and the crafts will stop loading. The parts should (in theory) have their status clearly stated in their names/descriptions in case you run across them.

The fuel tanks tab in your last screenshot looks correct (I think), are you sure the new versions of the avionics and fairing base aren't showing up?

 

Edited by CobaltWolf
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11 minutes ago, RyGuy_McFly said:

So the fact that the only Belle fuel tanks that show up for me under "Fuel Tanks" in simple mode in the VAB are the Belle-120A and the Belle-240BD (along with many, many other parts) is definitely a bug then?

 

Correct. Notice in that screenshot I have the 0.935m cross-section tab selected, using advanced mode.

Not a bug. Those two tanks are the only Agena tanks you should see. 

Looks like the names on the wiki are out of date. The numbers on the fuel tank correspond to the size. I guess the fuel tank quantities got changed after @Friznit made his diagrams. What is labelled 70A and 200BD in the diagram are in fact the 120A and 240BD. 

The development cycle took about a year so some details like this might have been missed in the wiki. But you can tell by looking at them they are the same tanks. Friz may correct the wiki when he has the time.

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4 minutes ago, Zorg said:

Not a bug. Those two tanks are the only Agena tanks you should see. 

Looks like the names on the wiki are out of date. The numbers on the fuel tank correspond to the size. I guess the fuel tank quantities got changed after @Friznit made his diagrams. What is labelled 70A and 200BD in the diagram are in fact the 120A and 240BD. 

The development cycle took about a year so some details like this might have been missed in the wiki. But you can tell by looking at them they are the same tanks. Friz may correct the wiki when he has the time.

Oh derp I didn't even notice that :P

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8 minutes ago, CobaltWolf said:

In response to the first - no, that is correct. There are fewer Belle tanks than before but I think the mod has more 0.9375m tanks as a whole now. Not every part received a 1:1 replacement in the update, for a variety of reasons. In this case I think it was simply that there were only two historical tank lengths. The new parts don't automatically replace the old ones (since we had to leave the old ones in to not break old crafts). You need to rebuild the crafts using only the new parts.

By viewing in the "advanced" mode (is that what the other sorting methods are called? I've never really used them), you've exposed something that we were unaware of - the old deprecated / hidden parts are still showing up there. They shouldn't be used and any crafts using them should be replaced if possible, since those parts will eventually be deleted and the crafts will stop loading. The parts should (in theory) have their status clearly stated in their names/descriptions in case you run across them.

The fuel tanks tab in your last screenshot looks correct (I think), are you sure the new versions of the avionics and fairing base aren't showing up?

 

I'd say it seems like a lot of content to strip, but it is a pretty bloated mod already so fair enough, I understand then. And yes, I can confirm that both the TRU and fairing are not showing in their respective tabs for me.

Payload tab:

t6X4paz.png

Command and Control Tab:

TBZNM5k.png

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4 minutes ago, RyGuy_McFly said:

I'd say it seems like a lot of content to strip, but it is a pretty bloated mod already so fair enough, I understand then. And yes, I can confirm that both the TRU and fairing are not showing in their respective tabs for me.

Payload tab:

Command and Control Tab:

Overall the number of parts grew, but that's why we started using the B9 part switches more to merge simpler parts when possible. Generally it was less stripping content and more just a restructuring of how things are built.

I think I see the fairing base, two rows above the cardboard box. (Is that the AKI one I made years ago? I'm pretty sure that mod stopped being supported when Breaking Ground released)

And wouldn't the avionics be in the uh. Pods tab? The one with the probe cores (since that's what it is). Again, curse my lack of actually playing KSP these days, I didn't catch that Command and Control meant the RCS tab.

Edited by CobaltWolf
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8 minutes ago, Zorg said:

Not a bug. Those two tanks are the only Agena tanks you should see. 

Looks like the names on the wiki are out of date. The numbers on the fuel tank correspond to the size. I guess the fuel tank quantities got changed after @Friznit made his diagrams. What is labelled 70A and 200BD in the diagram are in fact the 120A and 240BD. 

The development cycle took about a year so some details like this might have been missed in the wiki. But you can tell by looking at them they are the same tanks. Friz may correct the wiki when he has the time.

Ah, alright then. Well I am a little sad that the other tank sizes are now deprecated but I suppose there are workarounds to everything. I tend to use the advanced menu a lot while building, filtering by cross-section is extremely useful to me with all the part packs I have.

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7 minutes ago, RyGuy_McFly said:

I'd say it seems like a lot of content to strip, but it is a pretty bloated mod already so fair enough, I understand then.

Well functionally every part has been replaced. Not 1:1 since we do some things differently. More than that the Agena and derivative parts have been greatly expanded. Previously the complete list of Agena parts (the ones that have been gotten rid of) would have been around 15-20 parts (if even that). You have  a lot more Agena toys to play with now :)

screenshot174.png

screenshot175.png

 

Edited by Zorg
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6 minutes ago, CobaltWolf said:

Overall the number of parts grew, but that's why we started using the B9 part switches more to merge simpler parts when possible. Generally it was less stripping content and more just a restructuring of how things are built.

I think I see the fairing base, two rows above the cardboard box. (Is that the AKI one I made years ago? I'm pretty sure that mod stopped being supported when Breaking Ground released)

And wouldn't the avionics be in the uh. Pods tab? The one with the probe cores (since that's what it is). Again, curse my lack of actually playing KSP these days, I didn't catch that Command and Control meant the RCS tab.

Ah, you are correct on both accounts there. Again, the wiki just has the outdated names, and the Actual Fenris-4688 fairing is in fact still in the game if you know where to find it, which led to my confusion.

And that is the AKI box... I think it's in KIS now? No idea where that came from :confused:

Edited by RyGuy_McFly
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Just now, RyGuy_McFly said:

I tend to use the advanced menu a lot while building, filtering by cross-section is extremely useful to me with all the part packs I have.

  Yeah I think what it was, originally I assumed the Agena B had a tank length between the A and D? And so I just made one - I think there were only actually 3 lengths of tank, just multiple skins. Eventually it turned out there was only two lengths, which is what I made in the remake. It crossed my mind to remake the middle tank length but I think I didn't have time or the model didn't lend itself to being cut up that way or whatever.

And yeah, I totally can see how the other menus are useful. I usually don't have to use them since I know what 'simple' tab to look for everything in ;) But that also means I wasn't looking in there to notice the old parts still showing up.

Like Zorg said, the most recent update was sort of start/stop developed over a year with all of us having variable time to commit to the mod. We mean well but there's a lot that can slip through the cracks. :) 

 

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17 minutes ago, CobaltWolf said:

And yeah, I totally can see how the other menus are useful. I usually don't have to use them since I know what 'simple' tab to look for everything in ;) But that also means I wasn't looking in there to notice the old parts still showing up.

KSP's UI is just really bad once you got a large number of parts, heck even with just Nertea's mods it gets pretty crazy trying to find things and then with how many (incredibly high quality) parts BDB adds the problem gets even worse. I'm hoping that this is something that can be fixed in KSP 2.

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I agree with the reduction in total part numbers and higher use of variants via B9 Part Switch.  Being able to trigger between setups and textures to get what you need is much simpler and keeps the UI much less cluttered.  Since the Agena B & D main tanks (for example) are the same length but had different dome positions, using 1 tank for both made sense.  As well, having 1 tapered tank segment for the Atlas LV-3 made sense as well and allows you to set it for 4 or 5 different early Atlas configurations, meaning that you can take the same base "Atlas" subassembly and then just change that part to fit your upper stage as needed.  Saved me a ton of time as I work through History of Spaceflight to not need 50 different subassemblies because of this.

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1 hour ago, CobaltWolf said:

edit: also, for those keeping score at home, this morning my car battery died :')

Let´s hope you have better luck soon :(
 

1 hour ago, RyGuy_McFly said:

always remember to extend your cars solar panels when you park!

best answer to that :D

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Hello there, has anybody had problems with getting the Atlas booster skirt to separate? the part refuses to budge even with the separation motors and is rigid such that moving the craft will not kick the part out of the way. In addition, the part followed the craft all the way through the flight stopping to hover in mid air once the pod has splashed down.

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Fuel tanks often have names changed after a balance pass, so if you spot any errors or missing details (like dome switches) just leave a note in an issue ticket and I'll update the wiki!

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2 questions:

1. when did the 'high density acid' agena engine get used historically?

2. when did the 8096C get used, if at all?

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On the Subject of Agena,

Agena is one of the most boring stages to make.  There are so few parts to make one.  HOWEVER Agena is one of the most useful stages....   Although I submit the JPL 6K stage is equally useful (and a lot less boring to look at!)  

 

You have the TRU/GCU (Officially in USAF nomenclature it is a GUIDANCE CONTROL UNIT or GCU which is what I call it in all my posts.)   Bell/Lockheed may call it a TRU.

you have 2 and ONLY 2 tanks.

you have a single tank butt - Engine assembly)

you have 2 Equipment Racks.

That is Agena in a nutshell.

What isn't covered, is what makes Agena such a great upper stage:

Agena SOT (Drop) tank expansion more than doubles the d/V Agena can achive

Engine upgrades?   There are what, 7 in game right now with a potential of 5 more via simple bell extensions (8096C/L)

AFT rack SPS engines, developed for Gemini Agena Target Vehicle can further improve performance via extra thrust when you need it.

Ignoring the Harvester Signals Intelligence Birds, Agena makes a great Communication Satellite bus.   (Now why isn't there a JX2 antenna at 0.9375m diameter!?)

Agena is one of the few USEFUL upper stages with Storable propellant.   Sure, not as much fun as a Centaur.... but no Boiloff to worry about.

 

The Variants:

First off there is the "experimental" Agena A.   Each Agena A was custom built for it's specific mission.   No two were identical.   Some had extra batteries in the aft skirt, others carried extra RCS.

STANDARDIZATION:  Agena B and Agena D early production.  

  • The Guidance and Control Unit was updated to a unified standard (and would remain unchanged until the complete transistorization in the Ascent Agena.)
  • An improved larger fuel tank
  • Forward equipment rack was added.  This was originally for Engine restart hardware
  • as an alternative to the battery/RCS Aft Skirt, an Aft Rack was developed.  This is the primary visual difference between a standard Agena B and a Standard Agena D
  • hybrid stage Gemini Agena Target Vehicle is developed.   Utilizes the space frame of the Agena differently than the Standard B/D Agena.  
  • Spacecraft to Agena interfaces are custom built on Agena B but are standardized on Agena D for even better cost performance

 

NASA:

  • new versions of the Bell LR81 engine developed that uses small electrical bellows on the fuel and oxidizer tank for engine restart
  • This empties the forward Equipment rack.   Forward equipment rack is now used for batteries and experiments (as well as new light fixtures.)
  • Forward Helium bottle is superfluous and removed.   GCU is still hybrid vacuum tube and Transistor

Post GATV USAF:

  • Forward equipment rack either empty or loaded with batteries
  • Forward GCU Helium bottle is left in place for balance purposes but left empty.
  • Development started on lightened Ascent Agena
  • New restartable 8096 Engines using the electronic bellows developed for NASA

Ascent Agena USAF only:

  • Final 18 Agenas only! (listed as "AGENA" on order not "AGENA D" or some alternative)
  • Forward equipment Rack is deleted shortening the over all length
  • Updated to 8096B with HDA (that is IRFNA-IV in CRP for KSP)  This alters tank size slightly (4")
  • Overall mass down significantly as last of the Vacuum Tubes in the electronics are replaced with JFET or FET transistors.  possible limited use of basic ICs at this time.
  • Helium tank deleted from GCU,  GCU's mass down 200kg!

 

POST GATV NASA proposals:

  • SOT / Drop Tank Agena   Designed to be used on either expendable launchers or as part of a Space Shuttle Launching system
  • Growth Agena.   Large Diameter Agena variant proposed many times over the lifecycle of Agena.  3.05m (10ft) IRL diameter making it 1.875m in KSP scale.

 

In addition to the SOT tankage, there is the Growth Agena, which is a full up 1.875m stage in KSP (3.05m/10ft IRL)    This would require a whole ship-set of new parts, only re-using the Engines from the Basic Agena.  

Growth Agena can represent 2 other never flown "Agena" Derivatives.    Agena 2000 (was to fly with an engine that was not made by Bell Textron) was in-fact a 1.875m KSP scale stage for Atlas V-Light.   You can also make the very unknown (as in there is literally only vague references) Agena C which by said vague references was to be a 10ft Agena (3.05m AKA 1.875m in KSP scale.)  Agena C was canceled in favor of the much less ambitious Agena D (and that was probably a good decision.)

 

I hope this little short History of Agena as told by a guy who likes to dig into a bunch of crap and find these gems..... is helpful and showcases why Agena should be your upper stage of choice! :D

 

 

 

 

 

 

3 minutes ago, Starhelperdude said:

2 questions:

1. when did the 'high density acid' agena engine get used historically?

2. when did the 8096C get used, if at all?

HDA *MAY* have flown on the Ascent Agena.   Not enough documentation on Ascent Agena is in public domain to know for certain however..  I assume above that it flew on Ascent Agena however

8096C and 8096L are two "hypothetical" engines, they use the same hardware but burn different fuel ratios for significantly different thrust profiles.    8096C and 8096L  would have had 3 bell sizes and flown on Shuttle Agena or Later civilian Agena launches of one form or another.

Edited by Pappystein
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Early Bird aka Intelsat 1 - Delta D, CCAFS

Intelsat 1, also known as Early Bird, was the first commercial satellite placed on geosynchronous orbit. It was launched at 6 April 1965, on Delta D rocket, and served for four years - and after that, a short stint in 1969, when it was used as a spare transmitter for a small-ish space mission called Apollo 11.

7aBsmF3.png

Launched only twice, Delta D was basically a Delta C with three Castor 1 SRBs, borrowed from USAF's Thrust Augmented Thor-Agena. It had a notably high TWR (2.37) at liftoff.

5FgAWMz.png

Liftoff. The actual launch happened shortly before midnight.

Sec3lNc.jpg

Delta carries already spent Castors to safe drop zone.

Cq8wjXR.png

Jettisoning Castors (in clouds)

TwC6ljQ.png

Ww48q8D.png

xKw6QqK.png

Unfortunately, there is no suitable probe core in my install, so Early Bird is made from Pioneer 6 core. In reality, its size was about that of a garbage can or typical oil drum. There is no RCS either, due to weight limits (although the real satellite apparently had some).

Now, this is not just a launch, but a GSO launch, so this would require some flight planning. We are aiming at circular 5902km orbit (GEO altitude in 2.5x KSRSS), with the satellite placed above Atlantic (real one was placed at 28 W). KSRSS launches can be a lot harder here, especially if you launch from real locations - you have to figure inclination change into your burns.

MmE1BBm.png

First, we have to make a burn to GTO - and push our inclination towards zero as much as we can. I usually make a node at AN or DN with MJ, and then edit it. Things to note:

- If you use solid motor, use all the fuel. No need to save it - you'll jettison the SRM anyway.

- LIMIT YOUR THRUST. TWR < 1 is good.

- Pack RCS for precise maneuvers.

PjD7TN0.png

hZ5mPx4.png

NASVL80.png

You can see the final inclination: from 27 degrees to 11 degrees. This is a very good result.

ITPQpph.png

Now is the time to plan the GEO insertion burn. This one circularizes your orbit and brings inclination to zero. Most modern satellites do this in several small "puffs"; we'll do this in one.

You may have noticed a "relay" at LEO. This is my "targeting help" - it orbits at almost ideal 150kmx150kmx0deg orbit, and serves as a visual aid. Target the planet and then align your GTO-GEO orbit with it - which is exactly what I've done above.

X1y747h.png

bAnTmU3.png

Great inclination. Not so great orbit, though - it'll drift out quite soon. Not a problem if you have a motor on it, though (I don't...)

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On 7/12/2020 at 8:23 AM, pmborg said:

Hello @linuxgurugamer,

Yes that is the idea just to help, because @CobaltWolf might be in a busy week, and sometimes pointing directly to the problem/solution helps a lot the mod developer to speed up the fix, when we are busy to other stuff.

I understand your point.

The log is this (just before KSP crash/halt):

[LOG 10:29:44.662] PartLoader: Compiling Part 'Bluedog_DB/Parts/Antennas/bluedog_dipoleAntenna/bluedog_dipole'
[LOG 10:29:44.677] PartLoader: Compiling Part 'Bluedog_DB/Parts/Antennas/bluedog_domeAntenna/bluedog_domeAntenna'
[LOG 10:29:44.692] PartLoader: Compiling Part 'Bluedog_DB/Parts/Antennas/bluedog_LOantenna/bluedog_LOantenna'
[LOG 10:29:44.706] PartLoader: Compiling Part 'Bluedog_DB/Parts/Antennas/bluedog_LOdish/bluedog_LOdish'
[LOG 10:29:44.721] PartLoader: Compiling Part 'Bluedog_DB/Parts/Antennas/bluedog_mariner2Antenna/bluedog_mariner2Antenna'
[LOG 10:29:44.735] PartLoader: Compiling Part 'Bluedog_DB/Parts/Antennas/bluedog_mariner4Antenna/bluedog_mariner4Antenna'
[LOG 10:29:44.751] PartLoader: Compiling Part 'Bluedog_DB/Parts/Antennas/bluedog_mariner4Dish/bluedog_mariner4Dish'
[LOG 10:29:44.766] PartLoader: Compiling Part 'Bluedog_DB/Parts/Antennas/bluedog_rangerDish/bluedog_rangerDish'
[LOG 10:29:44.783] PartLoader: Compiling Part 'Bluedog_DB/Parts/Antennas/bluedog_scimatarAntenna/bluedog_scimitar'
[LOG 10:29:44.797] PartLoader: Compiling Part 'Bluedog_DB/Parts/Antennas/bluedog_simpleAntenna/bluedog_simpleAntenna'
[LOG 10:29:44.812] PartLoader: Compiling Part 'Bluedog_DB/Parts/Antennas/bluedog_solarAntenna/bluedog_solarAntenna'
[LOG 10:29:44.832] [DragCubeSystem]: Drag cubes not found or cannot be read for part Part. Generating New drag cubes.
[LOG 10:29:44.836] DragCubeSystem: Creating drag cubes for part 'bluedog.solarAntenna'
[EXC 10:29:44.877] NullReferenceException: Object reference not set to an instance of an object
    ModuleDeployablePart.AssumeDragCubePosition (System.String name) (at <c168e21ec56346b082f89043e76162e1>:0)
    DragCubeSystem+<RenderDragCubes>d__34.MoveNext () (at <c168e21ec56346b082f89043e76162e1>:0)
    UnityEngine.SetupCoroutine.InvokeMoveNext (System.Collections.IEnumerator enumerator, System.IntPtr returnValueAddress) (at <5aeafee3fea24f37abd1315553f2cfa6>:0)
    UnityEngine.DebugLogHandler:LogException(Exception, Object)
    ModuleManager.UnityLogHandle.InterceptLogHandler:LogException(Exception, Object)
    UnityEngine.Debug:CallOverridenDebugHandler(Exception, Object)

 

LINK to full: LOG: https://www.dropbox.com/s/anl9u2a6mop7v1t/KSP - BDB.zip?dl=0

 

Is this still happening?  I opened a ticket on the Bugtracker back in July, they are asking for more info.  If it's fixed, please let me know so I can close it

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So while I am finishing up my Covid lock-down (thankfully COVID wasn't too bad for me.)   I though I would publish at-least one more historical paper on confusing things to hopefully make them less confusing.

The Previous Article:

 

 

Today's subject is the J-2 Engine.

Like most of you I know of many J-2 variants,   and confusingly many of them have the same name.   Or multiple engines have the same name with a different suffex.

But we should start at the start.   NASA was looking for a new Hydrolox engine for their Saturn rocket.   They wanted something more powerful than the anemic but efficient Pratt and Whitney RL10 that was developed by happenstance.    A competition was opened, and won by Aerojet...   The LR87-LH2 beat out all the competition on 10 of 11 critical requirements.   The 11th requirement would be the killer however... as to meet the thrust requirements Aerojet would use TWO LR87s (much like they did under the Titan rockets!) instead of one.  This extra complexity in plumbing and mass (actually not much extra of either but to the bean counters it was a doubling.) prevented the LR87-LH2 from ever flying on a Saturn Rocket.   Add to the fact that at the time in question, Aerojet was in a CRASH* program to push through development for the afor mentioned Titan Rockets...... And Aerojet is set aside for the least technically complicated alternative choice, the Rocketdyne J2.  

The Decision to go with Rocketdyne is not without controversy.   Pratt and Whitney already knew many of the particular issues with burning Hydrolox in a Rocket engine.   On paper their engine was about as efficient and powerful as the proposed Rocketdyne J-2.   But Like Aerojet, Pratt and Whitney was currently devoting a lot of their engineering to solving problems with another rocket already... in this case the Centaur.  Only Rocketdyne had the engineering capacity to direct to a new Large Hydrolox project so by default Rocketdyne was tapped to engineer and manufacture the J-2.

I am not going to spend a lot of time here talking further on the politics of why Rocketdyne was selected (and bear in mind that it is Politics that determined their selection...)   Rather I am going to jump right into the meat.   The varinats:

Production J-2

Only one version of the J-2 was produced and launched.   During it's life-cycle we saw a steady improvement in thrust and a directly correlated improvement in ISP.     Beyond these changes to the turbopumps and plumbing to improve thrust, the J-2 engines that flew were all broadly identical.     There were 2 sucessive updates over the base engine resulting in the following power and ISP performance:

Initial Production:  889.6kn   418isp VAC

Early launches   1000kn 419isp VAC

Final Launches  1023kn 425isp VAC

PROPOSED J-2:

There were lots of proposals to alter the J-2.  Some of which got to the hardware stage:

First off is the J-2X (not to be confused by the entirely new rocket engine that is loosely based on the J-2 for the old Constelation program!)     J-2X isn't a single engine but rather a series of programs designed to improve performance or lighten mass of the engine (or both.)   

In it's initial run in the late 1960s (66 to 68 I believe,)  Plumbing, pref-light man-hours and basic mass was reduced.  To improve performance three engineering choices were presented, an inflatable "Air Mat" bell extension,  A retracted fixed bell extension (like used on the RL10B-2) and a multi part bell extension like used on portions of the LGM-119 Peacekeeper (MX) missile. were proposed.   Due to early cancelation (program was to run until 1970) a crash decision had to be made as to what to test.  As Rocketdyne was the only company looking at leveraging the Goodyear inflatable nozzle ideas they chose the "Air Mat"    While two J-2Xs were built with two sizes of Goodyear "Air Mat" extensions, they were never actually fired due to the end of J-2 Testing in the High Altitude chamber at Arnold.    Instead Nitrogen was pumped through shutdown engines to test the effect on the "Air Mat" it reliably extended giving hope that this technology could work.        This engine is in BDB 1.7 as the J-2X.

The SECOND J-2X program, would not keep it's name for long.  It quickly evolved into the J-2 (Simplified) program.  The J-2 (Simplified) program took what was learned from the initial J-2X program and applied it to standard J-2 Engines.   This further evolved the J-2's plumbing and connections and resulted in a reduction in man hours of work before flight by over 50% over the standard J-2 engine.   This helps to drive down launch costs so it is an important improvement.    The 2nd J-2X program would now be called the J-2S (s standing for Simplified.)   And even though the J-2 testing was long canceled, as part of the Space Shuttle program several J-2S engines were built and test-fired.   The J-2S is indirectly the first step on the road to the Rocketdyne RS25 SSME.   The J-2S is in BDB 1.7 as J-2S.  

The J-2S was NOT the last gasp of the J-2 for use on proposed Saturn Rockets.    During the initial J-2X program, new engine ideas were allowed to propagate and build into a series of 4 engines.  Some of which would not be fired until the late 1980s.     Not all are represented in BDB but all are presented here.

The AEROSPIKE is a unique bell-less engine.   It can be made in two ways, the linear aerospike and the toroidal aerospike.   Each has advantages and disadvantages.   for example, the Toroidal Aerospike is the heavier of the two options and can not be easily "enlarged" as thrust is directly proportional to it's size.  The Linear aerospike is less efficient but adds an ease of control and ease of increasing thrust by small changes in length.

TWO Aerospike engines were designed, the J-2T, and the J-2L.   Hopefully it is obvious that the J-2T is the toroidal and the J-2L is the Linear aerospike.    Rocketdyne chose to go for efficiency and made the J-2T Toroidal Aerospike.   Initially in prototype form it was good for 200,000 lbf (or 889.6kn also the same performance as the initial J-2)   After some re-working of the J-2S powerhead behind the aerospike, the J-2T was good for 250k lbf.  Hence in BDB the engine is called J-2T-200K or J-2T-250K depending on upgrades.

Sadly while there are pictures of the J-2T in an engine test stand burning, there are no clean pictures of an un-lit J-2T or pictures close enough to actually see what it looks like while burning.

As part of their advanced projects NAA Rocketdyne looked at enlarging the J-2T and found that by increasing it's size by a small percentage they could net 400,000 lbf thrust (about 1780kn)   While no hardware was built to this standard it would be possible to mount a single one of these on the MS-IVB stage. and by mass would be only slightly heavier than a standard J-2 for a huge increase in thrust and efficiency.  

 

 

But remember the J-2L was never built (and is not in BDB.)    Add twenty years and you get the X-33 Aerospace plane program.  One of NASA's many wastes of money to keep the boys and girls making rockets to still make rockets.    It calls for a Linear Aerospike in the design.   A Linear Aerospike called the RS-2200....  Who is made by Rocketdyne and is almost a part for part reproduction... of the J-2L!

976px-Twin_Linear_Aerospike_XRS-2200_Eng

The J-2L err excuse me the XRS-2200. :P

Here ends our tale of the J-2.  ERR WAIT no there are two more J-2s to talk about.

During the MLV program, various proposals for re-using Saturn hardware came into existence.     One, the Saturn INT-17,18 and 19 programs would use the Saturn S-II stage from the Saturn V as the first stage of a new rocket.   Now the J-2 Engine is incredibly efficient in a vacuum.  But gives up that efficency at higher pressures like say Sea level.  So as part in parcel to this proposal it was proposed to make a sea level bell for the J-2, and latter the J-2S was included in this.  The new bell would be approximately 50% shorter and offer an improved thrust and ISP at sea level.    The trade off would be that in a Vacuum the engine was sigificantly (almost 100 isp) less efficient.    But since the S-II stage was not meant to get all the way to space, the gains out weighed the losses.   The Sea Level J-2S engine is in BDB 1.7

 

The Last J-2 to mention, is a J-2 only in hereditary design process.   Rocketdyne decided to see what would happen if they changed the J-2s combustion cycle and increase pressure via a new turbopump arrangement.   The result, was the HG-3.   This engine, owing everything to the knowledge gained on the J-2 was related to the J-2 only in that a for mentioned knowledge.   No pictures have ever been uncovered of the HG-3 and the one drawing seen has a large triangular blob where the Turbopumps would be and thus can hardly call the drawing accurate.   The neat fact is the HG-3 would be about the same size as a J-2, would hit 315k lbf of thrust or 1400kn...  And have an ISP of a staggering 451 in Vacuum.   A Sea Level bell version would power the Saturn INT-17 mentioned above.   If I had to imagine how the HG-3 would look, I might see a smaller version of the RS25/SSME bell on a J-2S with the turbopumps enlarged slightly.   But that is just my head-canon visualization.    The HG-3 would be scaled up to become the RS-25/SSME after some further changes and tweaks.

 

 

Now the real confusing one! The modern J-2X has nothing in common with the original J-2 other than they looked at the original J-2 designs and said "Lets make a clean sheet engine and call it a J-2X to confuse everyone" cause you know they were supposed to put the old J-2 back in production with new materials...   At-least the F-1B is mostly a F-1A with new parts....

 

 

*a CRASH program (and the word CRASH is always capitalized) is an official US military program of paramount requirements that supersedes all other projects.   If your company is part of a crash program 100% of your workforce that can be MUST BE assigned to the CRASH program.   In the case of Aerojet, the CRASH development of the LR87/LR91 AJ5 engines too up so much effort that by the time they were ready to make space launchers out of the Titan the improved AJ-9 was so delayed that it flew on only a few flights.   The first 3 Titan III flights flew on Titan 2 engines, and by the end of the first Generation Titan III, the AJ-9 engines were progressively being upgraded to flight test models for the AJ-11.    BUT to be clear, NO Titan III flew with an AJ-11 engine and only three flew with the AJ-5 engines.    The AJ-11 engines were introduced into production for the Titan 23 series and later (excluding the 23G.)

Edited by Pappystein
Major changes after the photograph!
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OK so I had another small history nugget to share today.

With the upcoming (it ill get here SOON(tm)) Saturn Update for BDB.  I thought I should cover MLV.

Now MLV is not a rocket, but rather a large series of Rockets with two designation systems.   MLV and INT.    And it is confusing what each means.   

Unlike the previous posts this one will be pretty short as I am NOT going to cover any MLV or INT variants in this but rather what MLV and INT stand for.

MLV or Modified Launch vehicle is any rocket that uses Saturn V parts including one form or another of the Saturn S-IC stage.     Direct S-IC replacement stages count.

Conversely INT stands for INTermediate and represent anything that is Saturn IB or is a Saturn IB replacement.    Thus even though the Saturn II, used the S-II stage, it is an INT rocket in the INT-17, INT-18, and INT-19 rocket proposals, as it was intended as a replacement for the Saturn IB Rocket.

 

 

 

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5 hours ago, linuxgurugamer said:

Is this still happening?  I opened a ticket on the Bugtracker back in July, they are asking for more info.  If it's fixed, please let me know so I can close it

"Now" it's fine, thanks!

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Something new! Fairing for Strawman which was also used for POPPY. An extra variant of the Strawman probe core will have this fairing and there is a new dedicated 0.9375m to 1.25m base for POPPY (which we dont have in BDB but still its a cool fairing). Its also available as a variant on the generic 1.25m base (not pictured)

screen_2560x1920_2021-01-12_19-27-39.png

 

Strawman

screenshot163.png

screenshot165.png

POPPY

screenshot167.png?width=1433&height=806

screenshot168.png

 

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Before I get into the Addendum on the J-2:   Here is the original Article

 

 

J-2 an Addendum. 

So I realized that I forgot to mention one of the J-2X engine variants from the original J-2X program (not the 2nd program that became J-2S nor the 3rd program that is not even related to the J-2)

The original J-2L was not the Linear Aerospike I mentioned above.  Rather it was a L for LIGHTENED J-2.   This involved some wizardry in improving the turbo-pumps to reduce the mass of the Engine.   The Bell and other structures were left basically the same.  It is the Turbopumps that would be the main focus for each of the first two J-2X programs in one form or another.   And while not the final turbo pumps made for the J-2S, the J-2L's pumps were enough to consider making  a new production standard.   This was quickly swept under the rug as it where, when the original J-2X program was de-funded by NASA in early 1968, with only some basic hardware prototypes but not a complete engine manufactured.

 

I also want to mention that both of the first J-2X programs were basically the same program with two separate times of funding by NASA.   The interruption co-insides with the Apollo 1 Fire, and the fallout that NASA faced over it.   The J-2X program was meant as a continuous (for the lifecycle of Saturn Rockets) improvement program to develop newer technologies to make the J-2 better, more powerful and cheaper.   Not necessarily all at once.    What grew out of the J-2X program was a slew of J-2 variants I covered above and the J-2X program is what gave NAA-Rocketdyne the leg up on the competition for the Space Shuttle Main Engine (RS-25 or SSME)

Here is a concise list of the J-2 variants in BDB (and at-least prototyped in the real world)

J-2srs 1 srs 2 and srs 3 (All just called J-2)

J-2X

J-2S

J-2S Sea Level

J-2T 200K and 250K

J-2T 400K (Extras folder) Unknown if this was actually built but there are enough design drawings to confirm it was at-least designed for manufacturing.

HG-3 and HG-3 SL (Extras folder just re-uses J-2S models and is not representative of how a real HG-3 would look)  

 

With the exception of the J-2T 400K these engines can drop in replace the J-2 on just about any launcher.   The J-2T 400K is too large to easily use on the S-II stage and is only really viable in the single Engine S-IVB stage.

 

NOT in BDB but in some way shape or form prototypes in the real world

J-2L (lightened bell type)  Some hardware but no complete engine was ever made as was quickly surpassed by the lighter and cheaper J-2S design.

J-2L (Linear Aerospike aka XRS-2200)  as stated above the XRS-2200 is almost a part for part reproduction of the J-2L design.   The major differences occur at the Linear Aerospike itself given almost 20 years of engine technology growth (and improved metallurgy)  The XRS-2200 actually used a produced but never flown J-2S power head.

 

 

 

Edited by Pappystein
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