Graphs of Engine Comparison Flights

[Dispatcher]

Edit: the most practical graphs here yet are found below in post # 6. Just added. Compares max mass and altitude.

Hey everyone. After seeing Tavert's impressive graphs, I made some admittedly simple graphs based on the results of test flights I did for my old chart (see sig line).

The first is of the maximum mass an engine can vertically launch from KSC:

Note that the Ion engine launches with more mass than its neighbors due to its electricity requirements; as opposed to it actually flying at all from Kerbin's surface.

Second is the maximum altitude reached when the mass maximum consists mostly of fuel:

At this scale, some engine results aren't visible, or too low to judge.

Third is the altitude reached when using only the small(est) fuel tank:

Some fuels obviously are specialized; such as Xenon for the Ion engine.

Fourth is the altitude reached when the mass is maxed, but with 50% non fuel:

Again, the scale is such that the lesser results are not easily discerned.

(Edit: replaced a trivial graph with a more useful one.) Lastly, this graph compares the 2nd and 4th results (max fuel vs. half non fuel altitudes), so a pay-loaded craft would probably reside at a point somewhere on the length of a line:

As far as graphs go, any real comparison of the "lesser" engines would best be done by excluding the more powerful engines.

Edit: The following are based on graphs above, however the data for the highest achievers in each is excluded so that results for the remainder are clearer. However, the average in each retains the excluded data.

The Aerospike engine (using diameter 1 parts) is excluded in this graph:

The next two graphs exclude the air breathers:

The next graph excludes the Aerospike (diameter 1 parts) and the LVT-30 engines:

Note in this last graph that the data for the 50% non fuel altitudes begins to resolve at this scale. Also, the altitude where a craft or launch stage using 75% fuel by launch mass would be a point midway on each line.

I hope these will be useful; especially in conjunction with other charts and tools at the forums or elsewhere.

Edited February 5, 2014 by Dispatcher
Added closer looks at all but the highest achievers.

[Dispatcher]

Added 4 graphs (based on the above graphs); excluding the best achieving engines. This further clarifies the results of the remaining engines. Former averages have been retained.

Depending on the graph, excluded engines include the Aerospike, air breathing and LVT-30 engines.

[Alexandicity]

Always love to see data! Some comments on these graphs if I may

* Units! Label the axes so we are completely unambiguous about what data is being presented.

* Some more commentary on how we could use these would be nice. For example, the first one - I'm not sure how I can use this data to help me. Ultimately, any engine can lift any mass, if there's enough of them. I presume what you're getting at is at what mass the S/C's TWR (Thrust-Weight Ratio) becomes less than 1 (i.e., won't take off on a given body vertically), presumably on Kerbin.

* On plots #2, 3, 4, 6, 7 and 8, it would be good to add text to the pots themselves (as you do in #5 and #9) as the sheer number of colours makes it hard to tell which is which. Also, I'd get rid of the 3D effect; as it is purely cosmetic.

* In a similar line, the 3D plots of #5 and #9 are inappropriate for the data being presented. A 2D graph with many lines on it would be better (ie., this one as viewed from the side, as it were). A 3D plot like this is only acceptable if the engines were continuous data; but engines types are not (they are categorical data)...

Keep on plottin'

[Dispatcher]

Thanks for the comments, Alexandicity. I think you will find the following to be helpful. First, all of the graphs above are plotted from data on the spreadsheet linked at my signature line. Second, here is where I explain my engine testing: http://forum.kerbalspaceprogram.com/threads/65937-How-I-tested-the-stock-engines-of-Squad-s-Kerbal-Space-Program

I suppose that some ambiguity will occur without the context of the referenced chart. Your presumption on at what point the TWR fails to lift mass is correct; again the context (and some explanation) is had on the engine spreadsheet. All launches occur on the KSC pad. The idea of the first graph (and the base testing) is that one can get a practical idea of how engines compare (hence the 3 and 2 radial combinations alongside the single stacking engines). I believe that you know that the altitude scale of all graphs is in meters. The subsequent graphs (well, most of them) deal with the same mass per engine as is found on the first graph. The second graph deals with the altitude when most of the mass is fuel. The third graph deviates in that the altitude results are of each engine using only one small fuel tank. It demonstrates the efficiency of an engine (or set of radials) in a real simulation way. The fourth is back to using the mass shown on the first graph; this time about half of that mass is non-fuel. The fifth graph attempts to convey the range between about 100% and 50% fuel by mass, in terms of altitude reached. The additional four (graphs 5-9) are repeats, with the most powerful engine results excluded so that the remaining engine results are easier to compare.

Graphs 5 and 9 attempt to show the altitude range for each engine, albeit with engines side by side; thus the 3D plot. As for the 3D look and colors; I'd love to blame Calc for that.

I'd consider the tests more useful to beginners, but veterans might find them useful too.

Thanks for the feedback! I'll keep what you wrote in mind. I expect to do more testing at some point; if only when new engines/ tanks are introduced into the game.

[Specialist290]

Most impressive. I find these much easier to follow than the old spreadsheet format

[Dispatcher]

Here are two more graphs; probably more useful than any of the above. By converting meters to kilometers, I'm now able to show maximum mass AND maximum altitude (in this case with 50% non fuel) on the same graph. The first one is with the RAPIER (air mode) and the second omits it, but retains the average.

Read the blue bar as mass in tons and the orange bar as altitude in kilometers.

Due to the 50% non fuel situation, only the maximum mass (but not the altitude) of the SRBs is shown. Also the same with the Aerospike with dia. 2 parts altitude. See the chart in my sig line for those, in the appropriate columns.

Edited February 5, 2014 by Dispatcher
Better graphs.

[Mr. Speed]

I see my love for the LVT-30 is justified.

[Kirogn 1]

on the first graphic, what does the 2 3 and dia 2 etc mean. for example what is the difference between small booster (2) or small booster (3).  PS awesome graph it's really helpful

[Dispatcher]

10 hours ago, Kirogn 1 said:

on the first graphic, what does the 2 3 and dia 2 etc mean. for example what is the difference between small booster (2) or small booster (3).  PS awesome graph it's really helpful

Good questions (and a reminder that my graphs can be a bit cryptic).  The "2" or "3" mean 2 or 3 radial engines were tested on a particular line.  The diameter 2 or 1 was used due to performance differences for the Aerospike engine between what are now called small and medium diameter fuel tank assemblies.  My latest testing indicates that this information is now outdated and the 'spike's performance is not adversely affected by the diameter of the tanks used in a craft.

My more recent graphs and explanations are found here:

http://forum.kerbalspaceprogram.com/index.php?/topic/133878-engine-launch-graph-for-ksp-105/

You will see that my testing approach has been modified and explained.  I hope you'll find these useful (or at least entertaining, hehe).  The most recent chart (not graph) I have is a little old, and linked in my sig line.  After KSP version 1.1 is released, I'll do new testing and create new graphs based on a new chart, based on updated results.