Saturn_v_rss

[Razorcane]

pretty sure you mean 36 *tons* dry (Although my references mostly say 39t dry)

And, actually, this mod is an INT-21, so...dry mass would probably be higher. But Piwa is making the S-IVB, so best to leave S-II at ~36-39t dry.

Piwa, I'll try tomorrow with a ~100,000kg reference payload, and real stats.

No I didn't.... >.> <.< Anyway, it's changed now. I think that you're going to need a dummy S-IVB to simulate it properly, and put the payload on top(which would obviously be less with the S-IVB).

[Piwa]

I took the numbers from one article:

* Dry weight - 42.7

Rocket weight (with adapter) - 458.7 (approx.)

max Thrust - 5096

Isp-1 200 - 0 421

[Piwa]

Actually the Vacuum isp of the S-II is 421 seconds. It's possible that your mass is wrong, or thrust is wrong. Make sure that thrust is 4,400, dry mass is 36t, and gross mass(fuel mass + dry mass) is...480t, if I'm not mistaken. Also, I'm not sure how you set up your configs, but the real Saturn V doesn't get to orbit on the second stage. It burns for 165 seconds on the third stage for it's final push to orbit.

As I recall two steps are not taken in orbit "Apollo." And as Skylab, but I oshibatsya? Skylab weighed 77 tons and exported in two stages. :\

[Piwa]

pretty sure you mean 36 *tons* dry (Although my references mostly say 39t dry)

And, actually, this mod is an INT-21, so...dry mass would probably be higher. But Piwa is making the S-IVB, so best to leave S-II at ~36-39t dry.

Piwa, I'll try tomorrow with a ~100,000kg reference payload, and real stats.

Thanks for the help! maybe I'm wrong chose these numbers ... But 70 tons of missiles should export two steps, I not even can throw into orbit 40 ...

Edited January 22, 2014 by Piwa

[Razorcane]

As I recall two steps are not taken in orbit "Apollo." And as Skylab, but I oshibatsya? Skylab weighed 77 tons and exported in two stages. :\

Yes, but Skylab only went to LEO, and it weighed half of what S-IVB + Apollo spacecraft did. The Apollo missions required the third stage to burn to achieve orbit. The Apollo CSM to Skylab missions used a different rocket altogether, the Saturn-IB.

ï ýõ óþòþрю ýð ñþûьшþü руÑÂÑÂúþü ÑÂ÷ыúõ, ýþ õÑÂûø ÑÂтþ ÿрþщõ ôûѠòðÑÂ, Ѡüþóу ÿþÿрþñþòðть. I hope I said that right...I only took one course in Russian.

[Piwa]

Yes, but Skylab only went to LEO, and it weighed half of what S-IVB + Apollo spacecraft did. The Apollo missions required the third stage to burn to achieve orbit. The Apollo CSM to Skylab missions used a different rocket altogether, the Saturn-IB.

ï ýõ óþòþрю ýð ñþûьшþü руÑÂÑÂúþü ÑÂ÷ыúõ, ýþ õÑÂûø ÑÂтþ ÿрþщõ ôûѠòðÑÂ, Ѡüþóу ÿþÿрþñþòðть. I hope I said that right...I only took one course in Russian.

Yes, I know, but still Skylab captured two stages, respectively, S-IC, S-II the ability to export into orbit about 80 tons, my rocket can not, he can not be put into orbit weight in kilograms... Seeking the reason for this oddity and waiting for help from Nathan.

P.S. let's here to communicate in English, although you communicate well in Russian

[Razorcane]

Yes, I know, but still Skylab captured two stages, respectively, S-IC, S-II the ability to export into orbit about 80 tons, my rocket can not, he can not be put into orbit weight in kilograms... Seeking the reason for this oddity and waiting for help from Nathan.

P.S. let's here to communicate in English, although you communicate well in Russian

It's probably the ascent profile. On stock Kerbin, it's not really that big of a deal, but with RSS, it becomes quite pronounced. Again, it's entirely possible that your values are off. Here are the values that I used with a full Saturn V stack, including the Lunar Module, CSM, and Lunar Module Adapter(the flower petal thing), and it made it into orbit.

S-IC

----

Empty Mass: ~131,000 kg

Gross Mass: ~2,300,000 kg

Thrust: 34,020 kN

Isp(SL): 265 seconds

Isp(Vac): 304 seconds

Burn Time: ~150 seconds

Fuel: RP-1/LOX

Fuel to Ox Ratio: 2.37

S-II

------

Empty Mass: ~36,000 kg

Gross Mass: ~480,000 kg

Thrust: 4,400 kN

Isp(SL): 228 seconds

Isp(Vac): 424 seconds

Burn Time: ~360 seconds

Fuel: LH2/LOX

Fuel to Ox Ratio: 4.38

S-IVB

------

Empty Mass: ~9,800 kg

Gross Mass: ~120,800 kg

Thrust: 1,000 kN

Isp(Vac): 424 seconds

Burn Time: ~165 seconds, ~335 seconds

Fuel: LH2/LOX

Fuel to Ox Ratio: 4.38

I forgot to mention the fuel ratios. Because LH2 is so much lighter, you can fit a lot more of it, and therefore increases your overall delta v. Make sure that your ratios are right, that is one of the key components for delta-v. I know that if you use the default mixture ratio (0.9 and 1.1), and you switch to one that is proper with LH2/LOX, you can quadruple(possibly more) your delta v.

And thanks. I have trouble speaking it(I skipped those lectures), but I can read it fairly well. I'm the same with German and French, although I can still kind of speak German.

Edited January 22, 2014 by Razorcane

[Deathsoul097]

Your SI-C is not going to be that weak. 4,400kN? That's the thrust of the S-II. IIRC, the S-IC had a thrust of 33,400kN.

The ISP of the J2 is about 200 ASL, and 420 VAC. The ISP of the F-1 is about 265 ASL, and about 300 VAC. (No wonder my Saturn V was only half the mass, my engines were incredibly efficient in comparison.)

Also, be careful with your ratios of fuel, especially considering the incredibly low density of LH2. You will probably want to use the documented ratios from astonautix or Wikipedia. (I personally recommend the former. Wikipedia is a bit dubious when it comes to correct info on rockets.)

I believe that the F-1 used about 2.27 units of LOX for every unit of RP-1.

Edited January 22, 2014 by Deathsoul097

[Razorcane]

Yea apparently when I copy/pasted I edited the wrong one. It's fixed now.

Also, I'm pretty sure my measurements are right, or relatively right, since my vehicle flew as it was supposed to. Also, I couldn't find the Isp(SL) of the J-2 in any of my records, but I used math to determine that number. Since I'm terrible at math, I'm probably wrong. The SL Isp generally doesn't matter though, since you're already well out of the lower levels of the atmosphere by the time those engines fire up.

[Deathsoul097]

Yeah, I know you get pretty high up, but the atmo ISP still plays a major part, because the Thrust depends on air pressure and the specific impulse of your engine.

[Razorcane]

Yeah, I know you get pretty high up, but the atmo ISP still plays a major part, because the Thrust depends on air pressure and the specific impulse of your engine.

The S-II in real life doesn't fire until they are already out of the atmosphere. I mean, the number is there regardless of whether it is used or not, but generally you don't need to calculate Isp for the atmosphere if you're engines aren't being fired in the atmosphere. I mean, Isp is just a measurement. It's there regardless of whether or not we give it a number. My particular H-II was above the 2 lowest levels of the atmosphere, which made the Isp a value of 424 on ignition.

[Piwa]

It's probably the ascent profile. On stock Kerbin, it's not really that big of a deal, but with RSS, it becomes quite pronounced. Again, it's entirely possible that your values are off. Here are the values that I used with a full Saturn V stack, including the Lunar Module, CSM, and Lunar Module Adapter(the flower petal thing), and it made it into orbit.

S-IC

----

Empty Mass: ~131,000 kg

Gross Mass: ~2,300,000 kg

Thrust: 34,020 kN

Isp(SL): 265 seconds

Isp(Vac): 304 seconds

Burn Time: ~150 seconds

Fuel: RP-1/LOX

Fuel to Ox Ratio: 2.37

S-II

------

Empty Mass: ~36,000 kg

Gross Mass: ~480,000 kg

Thrust: 4,400 kN

Isp(SL): 228 seconds

Isp(Vac): 424 seconds

Burn Time: ~360 seconds

Fuel: LH2/LOX

Fuel to Ox Ratio: 4.38

S-IVB

------

Empty Mass: ~9,800 kg

Gross Mass: ~120,800 kg

Thrust: 1,000 kN

Isp(Vac): 424 seconds

Burn Time: ~165 seconds, ~335 seconds

Fuel: LH2/LOX

Fuel to Ox Ratio: 4.38

I forgot to mention the fuel ratios. Because LH2 is so much lighter, you can fit a lot more of it, and therefore increases your overall delta v. Make sure that your ratios are right, that is one of the key components for delta-v. I know that if you use the default mixture ratio (0.9 and 1.1), and you switch to one that is proper with LH2/LOX, you can quadruple(possibly more) your delta v.

And thanks. I have trouble speaking it(I skipped those lectures), but I can read it fairly well. I'm the same with German and French, although I can still kind of speak German.

My Rocket parameters:

//---S-IC ---

Dry Weight (without engine F-1): 93.1

Gross Weight: 2103

F-1: Weight 8.4 - 5 X 42t (Total S-IC and F-1 = 2145 tonnes) -Max thrust: 6.773 - 5 X 33,865

Isp: (SL) 263 (VAC) 315

Fuel: Kerosene/LOX

Working time: 177 sec

//---S-II---

Dry Weight: 42.7

Gross Weight: 458.7

Max thrust: 5096

Use: (SL) 200 (WAC) 421

Fuel: LH2 / LOX

Working time: 260 sec

Yes I use ratio 0.9 - 1.1

[Piwa]

Your SI-C is not going to be that weak. 4,400kN? That's the thrust of the S-II. IIRC, the S-IC had a thrust of 33,400kN.

The ISP of the J2 is about 200 ASL, and 420 VAC. The ISP of the F-1 is about 265 ASL, and about 300 VAC. (No wonder my Saturn V was only half the mass, my engines were incredibly efficient in comparison.)

Also, be careful with your ratios of fuel, especially considering the incredibly low density of LH2. You will probably want to use the documented ratios from astonautix or Wikipedia. (I personally recommend the former. Wikipedia is a bit dubious when it comes to correct info on rockets.)

I believe that the F-1 used about 2.27 units of LOX for every unit of RP-1.

No, not from Wikipedia. Here's an article from which I took the settings but it is in Russian: http://www.plam.ru/tehnauka/pilotiruemye_polety_na_lunu/p4.php

[Razorcane]

Yea, adjusting your fuel ratios would definitely fix the problems. Deathsoul may be right about the 2.27, but the math I did gave 2.37. Astronautix only gives general mixture ratios; it doesn't go into detail, which is why I do the math myself. Mixture ratios for LH2/LOX aren't always 5.00, beacuse I've seen rocket configurations between 4.2 and 5.8 mixture ratio for that fuel. My values may not be 100% correct, but they should be a good starting point for you to re-configure the Saturn V. Actually, I went back and re-did my math, and here are the updated values(sorry, I'm not really that great at math):

S-IC: 2.32

S-II: 4.45

S-IVB: 4.38

Again, these probably aren't exact, but they should provide a good starting point for tweaking.

[NathanKell]

https://www.dropbox.com/s/mtelvbwg143sea5/SV_patched.zip

Here's some changes, and set for Real Fuels. Masses work out; I changed the node sizes for RO standards, and moved the fairing node apart for symmetry (also the nodes on the S-IC, so the F-1s can be mounted in symmetry).

I have also altered the F-1 to use RF and to use careo's ExsurgentEngineering SmarterGimbal, so it can be used for roll control.

With those changes I can easily get a reference 100t payload into a 500x200 orbit with about 40,000 liters of propellant remaining in the S-II.

A couple suggestions:

1. Make the J-2s independent models. This will allow roll control on the S-II (like on the S-IC) if they use an improved gimbal. Also it will let you reuse it on the S-IVB, and in any other things.

2. Make a second decoupler part for the top of the S-IC, so that the S-II interstage can be left attached to the S-II on separation. Give it some solids for ullage thrust (you already modeled them), put the decoupler at the top, and make sure the collision mesh is only the ring so the engines can fire through. That will match how it worked and provide ullage control for the second stage ignition.

[Razorcane]

https://www.dropbox.com/s/mtelvbwg143sea5/SV_patched.zip

Here's some changes, and set for Real Fuels. Masses work out; I changed the node sizes for RO standards, and moved the fairing node apart for symmetry (also the nodes on the S-IC, so the F-1s can be mounted in symmetry).

I have also altered the F-1 to use RF and to use careo's ExsurgentEngineering SmarterGimbal, so it can be used for roll control.

With those changes I can easily get a reference 100t payload into a 500x200 orbit with about 40,000 liters of propellant remaining in the S-II.

A couple suggestions:

1. Make the J-2s independent models. This will allow roll control on the S-II (like on the S-IC) if they use an improved gimbal. Also it will let you reuse it on the S-IVB, and in any other things.

2. Make a second decoupler part for the top of the S-IC, so that the S-II interstage can be left attached to the S-II on separation. Give it some solids for ullage thrust (you already modeled them), put the decoupler at the top, and make sure the collision mesh is only the ring so the engines can fire through. That will match how it worked and provide ullage control for the second stage ignition.

Nice alterations! But are you sure he created meshes for the mod, instead of using older versions?

[Piwa]

https://www.dropbox.com/s/mtelvbwg143sea5/SV_patched.zip

Here's some changes, and set for Real Fuels. Masses work out; I changed the node sizes for RO standards, and moved the fairing node apart for symmetry (also the nodes on the S-IC, so the F-1s can be mounted in symmetry).

I have also altered the F-1 to use RF and to use careo's ExsurgentEngineering SmarterGimbal, so it can be used for roll control.

With those changes I can easily get a reference 100t payload into a 500x200 orbit with about 40,000 liters of propellant remaining in the S-II.

A couple suggestions:

1. Make the J-2s independent models. This will allow roll control on the S-II (like on the S-IC) if they use an improved gimbal. Also it will let you reuse it on the S-IVB, and in any other things.

2. Make a second decoupler part for the top of the S-IC, so that the S-II interstage can be left attached to the S-II on separation. Give it some solids for ullage thrust (you already modeled them), put the decoupler at the top, and make sure the collision mesh is only the ring so the engines can fire through. That will match how it worked and provide ullage control for the second stage ignition.

Nathan you are a genius! I don`t know what I do without you! Can I retire? =)

Answer to question 1. Engines on the S-II near unlike J-2, I go to J-2 independent models.

The answer to question 2. It's already done, change it to the version you sent.

I still poorly work do fashion, thanks for the help, but there are nuances from the S-IC should increase crashTolerance (it is discarded at the slightest inclusion Soild engines) and Rocket became permanently deviate from the course, I don`t know what causes it. Here are a few photos.

Everything is fine.

Rocket itself changed the trajectory.

I have set the standard sepratron 1, and S-IC exploded/

I will spend some changes, I will try to fix it.

Edited January 23, 2014 by Piwa

[NathanKell]

Aw, thanks. :]

Weird--I had no trouble with the crashTolerance set like other tanks and engines. You are using FAR and KJR, right?

[Piwa]

Aw, thanks. :]

Weird--I had no trouble with the crashTolerance set like other tanks and engines. You are using FAR and KJR, right?

crashTolerance easy fix does not work ModuleGimbal, changing the parameters does not change anything.

:Yes, I found the error and corrected it, everything works fine

Edited January 24, 2014 by Piwa

[Devinci]

I'm also working on my Saturn-V. I cannot achieve orbit yet due to low TWR in S-II and S-IVB. Also looking for a J-2 engine model otherwise I'll have to make one myself.

Information Overload!

[Deathsoul097]

You appear to have mounted your engines incorrectly on the first stage...

Other than that, this is incredibly similar to what I have made. What is the TWR on the second and third stages when they first start to burn? You also appear to be starting your gravity turn really late. You should start it at about 1km to 500m, depending on your TWR. The turn shape should also be closer to ~40 degrees. I found this to be the sweet spot for MJ in FAR and RSS. Also, it is easier to go to a lower orbit. Try about 200 instead of 300. (EDIT: I just checked out the real Saturn V's flight path, and it made orbit around earth at about 180km to 190km. Your shooting for nearly double that.)

Also:

There is a pretty good J2-X in Bobcat's American Pack. If you are going to release it updated for RO/RF/RSS, ask him permission first.

Could you PM me a download link for the F-1? I don't know if it is supported by RF, and I cant find it anywhere.

Edited January 24, 2014 by Deathsoul097

[Devinci]

You appear to have mounted your engines incorrectly on the first stage...

Other than that, this is incredibly similar to what I have made. What is the TWR on the second and third stages when they first start to burn? You also appear to be starting your gravity turn really late. You should start it at about 1km to 500m, depending on your TWR. The turn shape should also be closer to ~40 degrees. I found this to be the sweet spot for MJ in FAR and RSS. Also, it is easier to go to a lower orbit. Try about 200 instead of 300. (EDIT: I just checked out the real Saturn V's flight path, and it made orbit around earth at about 180km to 190km. Your shooting for nearly double that.)

Also:

There is a pretty good J2-X in Bobcat's American Pack. If you are going to release it updated for RO/RF/RSS, ask him permission first.

Could you PM me a download link for the F-1? I don't know if it is supported by RF, and I cant find it anywhere.

I'm using this F-1 addon: http://kerbalspaceprogram.com/f-1-engine-by-1096bimu/

I also downloaded the update link above to get it to use RP-1/LOX but I don't have gimbal anymore.

My TWR was 1.21 but I managed to get it upto 1.45 now with the updated F-1. I'll try the launch profile you suggested and see how it goes.

[Deathsoul097]

Ahh! Theres one problem! Your First stage is too small! A Saturn V had a Liftoff mass of ~3500 Tonnes, and a Liftoff TWR of 1.1 to 1.15. Increase the fuel in your first stage a bit more, and you will be having a much better time.

[Devinci]

Ahh! Theres one problem! Your First stage is too small! A Saturn V had a Liftoff mass of ~3500 Tonnes, and a Liftoff TWR of 1.1 to 1.15. Increase the fuel in your first stage a bit more, and you will be having a much better time.

I've been looking more to getting the same burn time values of 150s. What I have is very close . Otherwise I have made all tanks to 1/1 scale.

[Piwa]

I'm also working on my Saturn-V. I cannot achieve orbit yet due to low TWR in S-II and S-IVB. Also looking for a J-2 engine model otherwise I'll have to make one myself.

http://imagizer.imageshack.us/v2/1280x1024q90/69/q8cd.png

Information Overload!

http://imagizer.imageshack.us/v2/1280x1024q90/834/px5f.png

http://imagizer.imageshack.us/v2/1280x1024q90/856/ve1t.png

http://imagizer.imageshack.us/v2/1280x1024q90/191/1u9u.png

I'm working on J-2, the first release soon and it will also work on LH2/LOX.Greatly helps Nathan for which I very grateful to him.