NathanKell

Realism Overhaul Discussion Thread

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On 8/4/2017 at 10:21 PM, hypervelocity said:

@winged quick question for you mate! and first off, many thanks for creating RO configs for the great B9 parts, your effort is greatly appreciated, many many thanks!!!

the question I had is the following: how did you come about the engine's masses? I notice you set SABRE M to 8 tonnes, but I found the following working paper quoting the engine's mass at almost half of what you have in the RO configs - https://web.archive.org/web/20140127114808/http://www.reactionengines.co.uk/tech_docs/JBIS_v57_22-32.pdf (Page 31)

 

I want to get to orbit but I don't want to "cheat" my way to it (setting aside the fact I'm using non-existant engines for my planes :$)

I've looked at these paper again and I think that RO treats nacelle, inlet and bypass as a part of the engine so the actual mass should be around 7400 kg.

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thanks @winged, might this revisit be due to tyler raiz's skylon video - I saw your comment in youtube a couple days ago?

anyhow - I get your total 7.4t but that should include the air intake and the pre-cooler parts in RO, hence my thought that the engine part at 8 tonnes without air intake nor precooler was a bit off.

tyler raiz gets his skylon to orbit with reduced engine masses, similar to the aforementioned.

EDIT: skylon is boring though, I have left it behind and replaced it with a Nuclear Direct Cycle Turbo Jet SSTO

https://imgur.com/a/G1Bep

hOahFP7.png

Edited by hypervelocity

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13 hours ago, hypervelocity said:

thanks @winged, might this revisit be due to tyler raiz's skylon video - I saw your comment in youtube a couple days ago?

anyhow - I get your total 7.4t but that should include the air intake and the pre-cooler parts in RO, hence my thought that the engine part at 8 tonnes without air intake nor precooler was a bit off.

tyler raiz gets his skylon to orbit with reduced engine masses, similar to the aforementioned.

EDIT: skylon is boring though, I have left it behind and replaced it with a Direct Cycle Turbo Jet SSTO

1. Pre-cooler does nothing in RO, you don't have to use it.

2. where did you find config for that direct cycle?

 

With engine mass of 6,8 t and atmospheric TWR of 14 I've managed to put 12 t into low orbit. With 7,4 t that would be 10,8 t.

xwiwATe.png

Edited by winged
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Why is it so quiet here?

 

Here is a riddle for you: guess which of those tiny rockets is going to orbit today.

I0UjThr.png

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Nice looking stuff as usual @winged .  I'm guessing its quiet 'cause our lord and leader NK has gone off a bit ghosty. Somethingsomething real life and all. Probably the same kind of reasons why I don't fly rockets 10+ hours a week.

 

Made a tracking sheet as pre the formula https://docs.google.com/spreadsheets/d/1Qxn6qxyx63mMcxvk9IiQG2wqTZCQzn4EG8kBFG4LxTs/edit#gid=0

hopefully we don't get revisions never ending annoying mod makers into giving up.

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Hey, I am fairly new to RSS/RO, and more specifically rocket design. How do you guys make such small orbital capable launchers? My smallest is 57 tons and 27 meters tall, and 2m diameter at the first stage.

Here's a Google Drive folder with the craft file and screenshot.

Not sure how to add screenshots to a post.

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19 hours ago, Munar pilot said:

Hey, I am fairly new to RSS/RO, and more specifically rocket design. How do you guys make such small orbital capable launchers? My smallest is 57 tons and 27 meters tall, and 2m diameter at the first stage.

Here's a Google Drive folder with the craft file and screenshot.

Not sure how to add screenshots to a post.

This is a tutorial a bit outdated for an early orbiter: https://github.com/KSP-RO/RP-0/wiki/Tutorial:-Reaching-Orbit

Some of the parts are different now, but it should give you an idea of how to do it. Otherwise, it's hard to give you more specific suggestions without knowing what is the mass of payload you want to put in orbit, and if you are limiting yourself with regards to tech level.

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Ok, I am just using whatever tech, the best I can find, and I am launching a probe weighing 0.1t to a 200-230km orbit. One of my difficulties is engine selection, other than LR89 or 79, and the AJ10 series of engines. and the generic thrusters, the 1.xx and the 2.xx kn thrusters

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2 hours ago, Munar pilot said:

Ok, I am just using whatever tech, the best I can find, and I am launching a probe weighing 0.1t to a 200-230km orbit. One of my difficulties is engine selection, other than LR89 or 79, and the AJ10 series of engines. and the generic thrusters, the 1.xx and the 2.xx kn thrusters

Another strategy is to use the baby sergeants as a kick stage to circularise at AP (you can even use multiple stages of them).   

If you have plenty of time I recommend Nathan Kell's youtube series as tutorials.  Older (1.2.2 and RP-0, but better as a tutorial, it will teach you how to get to orbit, the moon, and interplanetary) https://www.youtube.com/watch?v=FGqPWHCbvdY .  Newer, (less tutorial focused covers most of the new stuff in RP-1) https://www.youtube.com/watch?v=lm884sCLRhw .

 

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I guess this has been asked before but what will be condition to update Realism Overall to a more recent version of KSP. My feeling is KSP 1.6 t the last major version of KSP, there mighr follow some patches but I don't think there will be any 1.7.

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Why does everyone always say that the most recent update is always the last? I've seen that as far back as 1.0... It doesn't make sense.

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5 hours ago, Munar pilot said:

How do you guys make such small orbital capable launchers? My smallest is 57 tons and 27 meters tall, and 2m diameter at the first stage.

1. Use as modern stuff as possible

2. Make your probe as light as possible. For instance cubesats from AIES can be scaled down to about 0,25 kg.

3. Use Procedural Avionics to create as light as possible guidance unit. Do not attach it to the last stage - use spin stabillisation instead.

4. Use solid fuel. Procedural SRBs can be easily miniaturized so you can create very small upper stages.

5. Use supersonic or hypersonic plane as a first stage. Staging at Mach 2.0 will save about 30-40% of LV weight, staging at Mach 6 - about 60%.

 

Here is an example. 775 kg launcher (orange rocket) - 15 kg payload. Just about the size of a sounding rocket and with a 0,25 kg payload it could be 2-3x lighter.

omrg8Xk.png

 

 

But if you're limited by early tech... that's a full different story. I remember that my first orbital capable launcher was just a replica of Vanguard: 10t vehicle - 3 stages: X-405, AJ-10, solid upper stage.

Spoiler

pBKcJ6D.png

 

Edited by winged

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3 hours ago, FreeThinker said:

I guess this has been asked before but what will be condition to update Realism Overall to a more recent version of KSP. My feeling is KSP 1.6 t the last major version of KSP, there mighr follow some patches but I don't think there will be any 1.7.

See https://forum.kerbalspaceprogram.com/index.php?/topic/155700-131-realism-overhaul-v1210-29-apr-2018/&do=findComment&comment=3509891

 

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10 hours ago, Munar pilot said:

Ok, I am just using whatever tech, the best I can find, and I am launching a probe weighing 0.1t to a 200-230km orbit. One of my difficulties is engine selection, other than LR89 or 79, and the AJ10 series of engines. and the generic thrusters, the 1.xx and the 2.xx kn thrusters

One of the most fun things in RO is using knowledge of what real engines are best at then using them appropriately.

NK-33 and Merlin 1D are the some of my favorite lower stage engines. One of the things that can kill you on getting into orbit is upper stage TWR. In my experience, it should be as low as possible, since that means that you probably have a lightweight engine, which is important. 

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Lets talk Mechjebs Landing Guidance and RO

Quit frankly this feature in mechjeb is a outright disaster when using realism overhaul engines. Im trying to get a set of Raptor engines to achieve powered landings using Mechjeb so I dont have to play suicide games with the suicide burn timers.

How do I get rid of that delayed engine startup? Mechjeb hates powered landings because it does not account for that delay. I also had to get rid of the limited ignitions as mechjeb was just firing all the ignitions like a machine gun! Basically I need the Space X Raptor engines from KK Lanchers pack with the ITS ship to land like it needs to. 

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37 minutes ago, lextacy said:

Lets talk Mechjebs Landing Guidance and RO

Quit frankly this feature in mechjeb is a outright disaster when using realism overhaul engines. Im trying to get a set of Raptor engines to achieve powered landings using Mechjeb so I dont have to play suicide games with the suicide burn timers.

How do I get rid of that delayed engine startup? Mechjeb hates powered landings because it does not account for that delay. I also had to get rid of the limited ignitions as mechjeb was just firing all the ignitions like a machine gun! Basically I need the Space X Raptor engines from KK Lanchers pack with the ITS ship to land like it needs to. 

You are completely right. Mechjeb doesn't have any logic internally to account for the RO-Engines features, so if you want to use Mechjeb successfully this is my recommendation:

- Disable limited ignitions (you can disable the limited ignitions for every engine changing the RealFuels settings I think)

- Disable unstable ignitions,etc.

- Create a MMPatch for the engines you want to use in order to: set minThrust to 0 if it has a greater number, disable throttleResponse, disable throttleCurve. 

- If you experience problems with the gimbal , you will need to remove the gimbalresponserate too.

- Regarding the delayed engine startup. I haven't managed to completely solve this problem. What I recommend is to switch from Landing At X to Land somewhere when you are close to land ( altitude < 10k) also I recommend to have a TWR at landing not greater than 2.2-2.5 because it will be too late when Mechjeb starts the engine.


Once you have done all this things you will have a Mechjeb-friendly setup which will allow you to do things like this video I recorded last week.

 

 

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Posted (edited)
11 hours ago, jrodriguez said:

You are completely right. Mechjeb doesn't have any logic internally to account for the RO-Engines features, so if you want to use Mechjeb successfully this is my recommendation:

- Disable limited ignitions (you can disable the limited ignitions for every engine changing the RealFuels settings I think)

- Disable unstable ignitions,etc.

- Create a MMPatch for the engines you want to use in order to: set minThrust to 0 if it has a greater number, disable throttleResponse, disable throttleCurve. 

- If you experience problems with the gimbal , you will need to remove the gimbalresponserate too.

- Regarding the delayed engine startup. I haven't managed to completely solve this problem. What I recommend is to switch from Landing At X to Land somewhere when you are close to land ( altitude < 10k) also I recommend to have a TWR at landing not greater than 2.2-2.5 because it will be too late when Mechjeb starts the engine.


Once you have done all this things you will have a Mechjeb-friendly setup which will allow you to do things like this video I recorded last week.

 

 

I don't want to sound rude, but basically you are suggesting to disable RO to get powered landings on RO...

My suggestion @lextacy would be to start playing around with KerbalOS - I know it might prove a tad challenging, but boy oh boy the feeling when you get it right!

EDIT: also was not there a "RO-mode" under MechJeb's settings that handles ullage & ignitions? I might be completely wrong here.

Edited by hypervelocity

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54 minutes ago, hypervelocity said:

I don't want to sound rude, but basically you are suggesting to disable RO to get powered landings on RO...

@lextacy

EDIT: also was not there a "RO-mode" under MechJeb's settings that handles ullage & ignitions? I might be completely wrong here.

Well, I had to do tradeoffs to use Mechjeb. But I understand that it is far from ideal.

Regarding RO-mode I haven't see anything but I will double check. There is a RSS ascent guidance.

 

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Posted (edited)

I got a custom window set up in mechjeb with velocity, suicideburn countdown, time to impact en altitude.
It helps you to count down a full suicide burn almost perfectly, most of the time I start the burn on half throttle 3 second ahead, then finetune it to 0.0 sec countdown so it lands perfectly.

 

Edited by DrLicor

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