Jump to content

[WEB] Online engine cluster calculator

blizzy78

By blizzy78
in KSP1 Tools and Applications

 Share

Recommended Posts

blizzy78

blizzy78

Posted
Posted (edited)

Looking for a developer to take over this software! See this thread for details.

Hi, based on Temstar's rocket calculation guide I have made an online engine cluster calculator:

http://blizzy.de/asparagus/

btn_donate_LG.gif

flattr-badge-large.png

This calculator can be used to configure an engine cluster layout for a central stack and attached booster stacks. It calculates which engines you need and how many of them, both for the central stack and the booster stacks in an asparagus-style staging.

Please let me know what you think or what can be improved about it. Thanks!

screenshot.png

Change Log


2014-05-22
- Updated for NovaPunch 2.04.

2014-04-08
- Updated for KSP 0.23.5 and NovaPunch 2.03.5.

2013-12-21
- Updated for KSP 0.23.0 and SMP 0.23.0.2.
- You can now choose to use thrust limiting.

2013-11-20
- Added RLA Stockalike 0.9.1 (6 new engines.)

2013-11-15
- You can now choose to calculate for best Isp at sea level.

2013-11-11
- Updated for SMP 0.22.0.2 and KW Rocketry 2.5.5.

2013-11-09
- Updated for SMP 0.22.0.1.

2013-11-08
- You can now choose to consider only true radial engines for the radial spot.

2013-11-04
- Updated for KOSMOS SSPP 4.7.2.
- Users may stop calculations at any time now.
- While calculating, the current best configuration is shown.
- Many more possible engine combinations are considered now.
- You can now choose to calculate for lowest total engines mass.

2013-10-18
- Updated for KSP 0.22.0, KW Rocketry 2.5.4, and NovaPunch 2.03.

2013-10-06
- Added a tutorial that shows how to build a complete rocket using a calculated cluster layout.

2013-10-05
- Updated for KW Rocketry 2.5.2.
- Disabled RD-0146 and RD-0146-N2 from KOSMOS SSPP because their atmosphere curve is not suitable for ascent.

2013-10-03
- Radial engines are supported now.

2013-10-02
- Updated for KOSMOS SSPP 4.7.

2013-09-30
- Updated for KW Rocketry 2.5.

2013-09-21
- Removed Aerospike and clones for the time being.

2013-08-31
- You can now chose to calculate for best TWR (complete vessel), best TWR (engines only), or minimum number of engines.
- Added informational tooltips for engines.

2013-08-20
- Updated for KOSMOS SSPP 4.6.

2013-08-18
- Added lots of engines from popular part packs.

2013-08-18
- Initial public release.

Source code on GitHub

Edited by blizzy78
Link to comment
Share on other sites
  • 2 weeks later...
blizzy78

blizzy78

Posted
  • Author
Posted

That is an excellent question, and I'm thinking about adding an FAQ section over time.

Here's what I do to construct a complete vehicle:

- Setup center stack according to the calculators recommendation. I use the Stretchy Tanks mod for the fuel tanks.

- Resize the tank so that according to Engineer or MechJeb the center stage has a TWR of 1.23. (This is a figure I've taken from Temstar's original configuration guide.)

- Add the booster tanks and engines and set up an asparagus-style staging for them so that TWR calculations from those mods will be correct.

- Resize the booster tanks so that the complete vessel has a TWR ratio as calculated in the "Vessel Totals" section of the calculator.

This has worked pretty well for me so far.

Link to comment
Share on other sites
acealeam

acealeam

Posted
Posted
Resize the tank so that according to Engineer or MechJeb the center stage has a TWR of 1.23. (This is a figure I've taken from Temstar's original configuration guide.)

This. How can it have a twr if there's no engines? :confused:

Link to comment
Share on other sites
blizzy78

blizzy78

Posted
  • Author
Posted

Oh, the point before "setup center stack" was to mean "add a fuel tank and put engines under it," according to the calculator's recommendations :)

Please note that it can all be done using regular fuel tanks, if you're in for some tedium.

Link to comment
Share on other sites
  • 2 weeks later...
blizzy78

blizzy78

Posted
  • Author
Posted

The only engines remotely useful for liftoff are the LV-RX "Fatman" and the LV-LX "Little Boy", which are both nuclear engines. The other engines are a liquid fuel engine and a solid rocket booster, both of which types I don't consider for the calculator. So in all, I don't think there's anything useful in that package to add to the calculator.

Link to comment
Share on other sites
  • 3 weeks later...
  • 4 weeks later...
blizzy78

blizzy78

Posted
  • Author
Posted

I have now modified the calculator to consider A LOT more possible combinations now. It is now possible to get stack layouts where there is no center engine, or where there are only radial engines. Unfortunately, the change does make the calculator a whole lot slower, too. This is most noticeable when activating one of the larger engine packs.

Link to comment
Share on other sites
blizzy78

blizzy78

Posted
  • Author
Posted (edited)

I have now found the culprit why the previous modifications made calculations much slower. It is actually quite simple: Increasing the number of spots where engines can be placed will increase the total number of permutations that will be considered. This is even more so if the number of spots in the center stack is increased. So this, coupled with the fact that more permutations are being considered now, drastically increased the total calculation time to get a result.

As a kind of "solution", I have now changed the default number of center stack radial engines to be 0 maximum. I gather that most designs will be using booster stacks anyway, so center stack radial engines can often just get in the way when constructing the lifter. The result of the change is a dramatic increase of calculation speed, even with all engine packs enabled. Of course, you can always add radial engines to the center stack if you so desire.

I have also done a few optimizations to the calculation to speed it up, but they won't really help much if there are many permutations to consider.

In other news, you can now choose to only consider true radial engines for the radial engine spots. For example, if you choose to use only true radial engines for those spots, you will no longer get a result where you are advised to use a LV-T30 in such a spot.

Edited by blizzy78
clarifications
Link to comment
Share on other sites
  • 1 month later...
blizzy78

blizzy78

Posted
  • Author
Posted

I have updated the calculator so that you can now choose to use thrust limiting. This can sometimes improve the results, at the cost of a slower calculation.

Note that I've placed a lower bound to thrust limiting of 80%. This means that a single engine can only be limited to 80-100% of its full thrust. For example, if an engine spot calls for a maximum of 100 kN of thrust, the calculator will never recommend a Mainsail for that spot, because it would have to be limited down to ~7%. Limiting engines that much does not really make sense, because their mass does not change, resulting in very poor TWR.

Also the calculator will limit thrust in steps of 5%.

Link to comment
Share on other sites
  • 3 weeks later...
SHaFT7

SHaFT7

Posted
Posted

ok, I must be stupid. I've been trying to make a 350t payload launcher using stock + NP, and I can't get it to go correctly. I get the engines together and start putting tanks on it, but when i drop in the payload, I have to add more fuel than the max weight stated to get enough dV to escape kerbin, and by that time my TWR is way below what it should be.

Link to comment
Share on other sites
blizzy78

blizzy78

Posted
  • Author
Posted

The vessel mass stated at the bottom includes the payload. So for a 350 t payload and a (default) payload fraction of 15%, the complete vessel would weigh in at about 2333 t. Did you see the tutorial below the calculator?

Also note that for using engines with a low Isp it might be necessary to lower the payload fraction.

Link to comment
Share on other sites
SHaFT7

SHaFT7

Posted
Posted

yeah, I did, and tried to follow it exactly. I end up with about ~3500dV, which obviously isn't enough to get it done. I've tried both with stretchy tanks and normal tanks. I can post screenshots later if needed.

Link to comment
Share on other sites
Guest
This topic is now closed to further replies.
 Share
Go to topic listing
×
×
  • Create New...