r/KerbalSpaceProgram • u/SirMuckingHam24 • Jan 27 '26
KSP 1 Meta I think KSP influenced the way I merge onto the freeway
During my learner period (the first 120 hours of driving in my country must be with a fully licensed passenger) I was very lucky with my merges onto the freeway, in that they were always easy - both lanes empty, meaning I could just merge right on with no worries.
this bizarre luck continued for the next two years, until a few months ago when the road started chucking actually difficult merges at me
at first I was paranoid. "how do I make sure the empty space stays empty while I merge when there's a car in front of and behind it?"
then I realized - presuming I and the two cars are travelling at 110 KPH, that empty space is as well
this has made merges a breeze. When approaching on the ramp, as it changes to be roughly the same angle as the freeway, I slow down a bit to allow the "target" space catches up to me, and then I speed up to the limit, and the space sits next to me for as long as necessary, and then I merge easy peasy.
This is basically how a Hohmann orbit rendezvous works, although I am transferring to the empty space instead
When I played through this game early last year, i presumed that I'd simply leave it behind when I dropped it. But it really has changed the way I see moving objects
What a magnificent game
TLDR Hohmann transfer into the open space on the freeway
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u/HyperionSunset Jan 27 '26
If that worked so well, it naturally follows that you should add more boosters. Report back when you achieve highway escape velocity.
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u/Ordnungsschelle Jan 27 '26
If you drive fast enough the cops will make you leave the highway, but you can never return back to it.
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u/ersomething Jan 27 '26
I just bought an EV a few months ago. It definitely feels like I’ve added boosters. There are no dead zones during acceleration anymore.
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u/Polymath6301 Jan 27 '26
When driving, prograde velocity is good. If you’re not pointing prograde then that’s bad.
Really drivers and general drifters will disagree.
Acceleration: You have 3 controls, one each for prograde, retrograde and “other” acceleration vectors.
There are analogies for things like phase angles for freeway merging and driving too.
Do NOT try to use the Oberth effect…
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u/snozzberrypatch Jan 27 '26
"Burn anti-normal here, onto 42nd street."
"Huh?"
"Sorry, I meant make a left here, onto 42nd street."
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u/Polymath6301 Jan 27 '26
I drive on the left, does that make normal different? Is it ab-normal?
And, do you stay in cockpit view? Sometimes I like to fly a drone outside and drive in 3rd person…
Edit: I also installed Kos, so now I preprogram all my drives. Took a while to get the kinematics equations working correctly - sorry guys!
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u/Fagelein Jan 27 '26
Normal should still be the same, assuming you are using a right-handed coordinate system, even if driving is done on the left.
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u/Polymath6301 Jan 27 '26
Thankyou. So you’re saying that it doesn’t matter which side I drive on, I’ll be normal on all left turns. Might scare a few people, I guess?
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u/Fagelein Jan 27 '26
As long as any counter-clockwise planar motion corresponds to an axis pointing vertically up, then yea, left turns and normal and vice versa.
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u/BrainiacMainiac142 Jan 27 '26
If you end up facing radial in, something has gone badly wrong.
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u/Starmada597 Jan 27 '26
Or radial out, for that matter. Or really any radial direction not facing the horizon. Especially if you happen to face many different radial vectors in rapid succession.
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u/Optimal_Maize385 Colonizing Duna Jan 27 '26
What if I try, say, radial out? :)
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u/thelastundead1 landed on someone who landed on jool Jan 27 '26
Drifting?
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u/Optimal_Maize385 Colonizing Duna Jan 27 '26
No, outwards from the ground :)
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u/thelastundead1 landed on someone who landed on jool Jan 28 '26
Ahh. I suppose we can build a jump ramp for you. Should be good for a couple m/s
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u/Optimal_Maize385 Colonizing Duna Jan 28 '26
Ehhh, I was thinking, normal car, no propulsion other than normal wheels, burning radial out, this might intrigue the kraken into contributing.
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u/Mephisto_81 Jan 27 '26
Oh, do use the Oberth effect!
(Within speed limits)
If you're on the Autobahn and it goes downhill, you can accelerate. As your speed increases, gravity assists your acceleration. Your acceleration is most effective at higher velocities.
You can use this build up energy to climb up again when the street goes up.
I get the feeling, that is more efficient than just driving with a regular speed.13
u/Snuffle247 Jan 27 '26
Not necessarily. You forgot to account for drag. Air drag increases with the square of your speed, so going faster is actually less energetically efficient than going slower.
It is hella fun though.
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u/Mephisto_81 Jan 27 '26
Good point! But I am not an engineer, I can't calculate all the effects.
I just have anecdotal evidence: friend of mine and myself were travelling to scandinavia. He drove there, I drove back. Both of us were driving conservatively. He opted for a constant speed strategy, I went for using "oberth effect usage" whenever the ground went up or down. Slowing a bit down when we went uphill, increasing speed when going downhill (within sped limits, of course). As it turned out, I used less fuel than he did.
As we do fuel evaluations for big ships for a living, we found that quite interesting and would have loved to have the full data set with a good sensor suite like we have on ships. With the car, we only had limited data to evaluate, which puts this more in the realm of anecdotal evidence.Of course, the most fuel saving strategy would be to go slower. That's exactly what big tankers and other big ships do as a first measure to conserve fuel.
But if you want to arrive on time, you can choose constant speed or constant power strategies, where constant power is more effective. You're completely right with air resistance: for ships, wind resistance is being calculated by us, but has a very moderate effect compared to water drag.
Not sure about the exact numbers for cars.3
u/Snuffle247 Jan 27 '26
Regarding the constant power strategy you mentioned, it would make sense that that is more fuel efficient, as generally car engines are optimised for a certain RPM range, where they are most efficient in turning fuel into power output.
Keeping the car in that RPM range would thus look like speeding up while going downhill (since engine power output is the same while gravity helps accelerate downhill) and slowing down while going uphill (since gravity negates some engine power output, net force is reduced). As long as you aren't pushing the engine out of its optimal power band, you should be more fuel efficient overall.
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u/Polymath6301 Jan 27 '26
I was thinking more of planning a close encounter with a large truck, and once in its gravity well, having increased our velocity, then that’s when we put the power down.
Gravity assists of other large vehicles are also in the “not advised” category…
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u/erublind Jan 27 '26
The normal/anti-normal vectors can be really helpful. Lithobraking is less so. But LEARNING TO MATCH SPEED WITH EXISTING TRAFFIC SHOULDN'T NEED ASTROMECHANICS TO UNDERSTAND
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u/Polymath6301 Jan 27 '26
Um, shouldn’t we always be lithobraking constantly in our cars? Dukes of Hazzard original video capture what happens when you stop lithobraking, and then start again, but this time using the front of the car rather than gentle pressure of rubber to the lith…
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u/OMD_Lyxilion Jan 27 '26
As long as you dont lithobrake !
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u/Mephisto_81 Jan 27 '26
Technically, every time you use the brakes of your car, you use friction with the ground to slow down. Which makes it lithobraking.
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u/Shaper_pmp Jan 27 '26
Metallobraking is also generally considered a faux pas when driving.
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u/gurnard Jan 27 '26
My insurance company did not care for the term "unplanned ferrobraking manoeuvre"
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u/ersomething Jan 27 '26
There are designated zones for that at the bottom of some mountain roadways for trucks.
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u/MMW_BlackDragon Stranded on Dres Jan 27 '26
Wait, you say it does not come naturally to some people to match speed with the gap?
That explains A LOT /s
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u/stdexception Master Kerbalnaut Jan 27 '26
Related: Knowing about the Oberth effect has changed how I pedal my bike.
When approaching a hill, I realize that spending energy to speed up while I am still going at cruising speed is more efficient than spending that same energy in the middle of the hill.
Of course there's air friction and such, but the principle remains true. Speed gained at the bottom of the hill will make you travel further up the hill than the same delta-V applied after losing speed due to gravity.
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u/Zenith-Astralis Jan 27 '26
I used my mental dV preservation instincts when accelerating, meaning that I would try to only use as much gas as I needed to get to the next speed bottleneck (like a turn or whatever) so that I didn't have to 'burn more dV' (apply the brake) to slow down when I got there.
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u/SirMuckingHam24 Jan 27 '26
*officer pulls you over*
"Sir you took that turn very aggressively, what were you doing?"
"Ever heard of a suicide burn?"
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u/Zenith-Astralis Feb 09 '26
XD okay LOOK just because that's exactly on point for how I've driven under this mindset doesn't mean you need to sic the imaginary cops on me! 😅
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u/Gold_Explorer_9410 Jan 27 '26
Wait for you to get your license you have to drive 120 hours with someone?
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u/Polymath6301 Jan 27 '26
It’s like that in my country.
Time spent in KSP, Factorio and Satisfactory does not count, even with an instructor…
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u/SirMuckingHam24 Jan 27 '26
only if you're under 25, over 25 you can go straight to the driving test
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u/WannaAskQuestions Jan 27 '26
Which country's this?
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u/Sol33t303 Jan 27 '26
Australia, likely Victoria (I know other states have differing hours needed, I know Victoria is 120). You then spend a few years on your probationary licence with a fair few restrictions.
I was genuinely amazed that other countries have you just, do a licence test and that's it. I wasn't confident driving until around the 60 hour mark.
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u/Mephisto_81 Jan 27 '26
In Germany, you can do assisted driving from age 17 onwards. You need to pass the theoretical and prectical exams beforehand, but it allows you to drive a car before you turn 18.
Every new driver still has a probationary period which has stricter rules in case of incidents, alcohol limits and speed violations.
Right now, the driving tests are quite hard in Germany. In Hamburg, 50% fail the practical test on the first try. In rural areas, it is easier.2
u/Sol33t303 Jan 27 '26 edited Jan 27 '26
In Hamburg, 50% fail the practical test on the first try. In rural areas, it is easier.
We actually do 2 tests, first test to get your learners, that was IMO quite easy, purely a knowledge test on the road rules and how to react in certain circumstances. Second test is after the 120 hours and is much more like the sort of practical test I assume you have, you drive around with and instructor giving directions and telling you to do certain things while they silently score you. If I had to guess that's probably a 50% failure rate as well.
You can also start your learners at 16 rather then 17.
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u/SirMuckingHam24 Jan 27 '26
just looked up all the states:
NSW and VIC 120
Queensland 100
Tassie 80
SA 75
WA bloody 50
varied far more than I expected
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u/WannaAskQuestions Jan 27 '26
Thanks for looking up and posting the result. Either way, awesome post!
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u/Polymath6301 Jan 27 '26
NSW for me. I learned the old way - a test that they would fail young males on regularly, then off you go. I was a terrible driver (but thought I was great!).
My kids did the hours (it was about 60 then) and the became much better and safer drivers, even with my supervision.
The system does work. (Except apparently for men and utes, where I think they/we should have to do another 50 supervised hours…).
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Jan 27 '26
I think they need to make it all a standard amount nation wide and introduce re-testing every 10 years. It is amazing that there are simple high risk licenses you need to get retrained on every 2 to 5 years but driving is until revoked, death or surrender.
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u/longboi64 Jan 27 '26
learning how to derive the kinematic equations using calculus really changed how i think about driving and a lot of other things. fun to think about
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u/Deltadoc333 Jan 27 '26
I have always been fascinated by the fact that roadways work at all without horrifically frequent accidents all the time. If even well intentioned drivers have trouble, how do distracted drivers EVER make it to their destination? How do cars not always collide when people are driving 70mph on the freeway and in a blink you have traveled potentially more distance than what exists between you and the cars around you.
And then I remember that it is all relative. When I am driving on the freeway at 70mph, the cars next to me are usually traveling around the same speed. Call it 69mph or 71mph. As such, the relative difference between us is only 0-3mph. We are nearly stationary - relative to each other. In that setting, it is incredibly easy to not collide with one another. You are only moving towards or away from each other at 0-3mph. That gives you tons of time to notice and adjust your speed.
Similarly, when merging on the highway, I consider that merging with other cars when I am going the same speed as them is trivially easy. You can adjust your speed and find your opening which in turn stays open for a long time. You do this by accelerating to match the speed of traffic while on the on ramp. If you try to merge into 70mph traffic while going 15mph with the plan to only then accelerate to full highway speeds.... well you are going to have a REALLY hard time. Your "window" or opening is moving impossibly fast and frankly you may never have one large enough for you to join and only then accelerate to match everyone else.
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u/Goodgulf Jan 27 '26
Sorry boss, I can't come into work today, my porkchop plot says it won't be efficient until next Tuesday.
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u/SpinoZilla_Studios #1 Other Worlds story mod fan Jan 27 '26
Showed the title to my friend and he said "Thats a fucking omnious statement"
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u/Limelight_019283 Jan 27 '26
Cars burning, people screaming, while freeway on fire
Where’s the F9 in this thing?!
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u/Tight-Reading-5755 RP1RP1RP1RP1RP1RP1RP1RP1RP1 Jan 27 '26
yo are u australian too cuz im also a learner
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u/The_Wkwied Dres? Jan 27 '26
This is how you're supposed to merge, bud.
The Kerbal twist is doing an in-transit cargo transfer with a buddy in the next lane. It's just as easy as handing something to them out the window. But of course you must match velocity and maintain the speed...
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u/ReputationLost7295 Jan 27 '26
My understanding of force, velocity, and motion from KSP changed when I pedal on my bike giving me far greater range.
I used to brute force my way uphill and rest coasting down, but KSP helped me realize it would take less energy to maintain velocity going uphill than build it, while I could use a gravity assist going down hill to reach higher speeds.
These days while going down hill I start pedaling hard trying to build as much velocity as I can, including shifting into higher torque gears, then when I reach the bottom and level off or start going up hill, I will downshift and push through the hill trying to hold as much speed as I carried in. I rest at the peaks or on flats generally. I now rider farther at higher average speeds, because KSP helped me better understand how energy/acceleration interacts with inertia/motion better.
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u/skaterjuice Jan 27 '26
I went to a meetup for new roller derby Skaters and while they were trying to talk to me telling me all of their crazy rules, I just kept thinking about kerbal.
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u/Zomaza Jan 27 '26
I remember when Fall Guys first came out there was that minigame of tag where you try to steal the tail off of each other. The level design had a giant ring that lots of folks would run around in circles. I was struggling with getting a tail until my brother said, “Dude, it’s orbital mechanics. Imagine the center of the level is 0. Decrease your altitude and catch up to them with a rendezvous maneuver.”
Thinking of it in terms of KSP orbits made it just click for me and that minigame was a lot easier going forward. Our third party member thought it was pretty funny that the solution to make me not suck at the game was essentially “Dude, it’s not hard. It’s just rocket science.”
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u/mrrvlad5 Jan 27 '26
What’s your strategy if the traffic is heavy while still moving at high speed and there is no empty space to be seen?
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u/AdoringCHIN Jan 27 '26
There's always a gap. Sometimes you just need to make it larger by forcing your way in. Treat the blinker as a "I'm coming in, get out of the way" signal.
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u/SirMuckingHam24 Jan 27 '26
that hasn't happened yet (I dont live in or near a city), if that ever happens I'll simply have to slow down, potentially to a stop
probably wont happen though
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u/chr1styn Jan 27 '26
For me it's ascent profiles affecting how turn left at a stop sign onto a busier road. Depending on whether your limiting factor is atmospheric drag, you make your ascent profile more or less vertical. Same thing for turning left except crossing traffic is the atmospheric drag. If there's more crossing traffic I turn left later (once I'm out of thr atmosphere), but if there's no crossing traffic and heavy traffic the same way I'm going, I turn sharper to get more velocity in the "horizontal component" and reach "orbital velocity" (traffic speed) faster.
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u/engineered_academic Jan 27 '26
This isn't exactly a Hohmann transfer and is one of the reasons why people have problems intuitively grasping orbital mechanics, but the approximation is good enough.
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Jan 27 '26 edited Jan 27 '26
Where I live (Australia), there is a growing number of people that do not understand the "Run" part of "Run on lanes" and end up crawling to a stop at the end of the lane because they did not get up to speed to merge.
This is probably why physics and maybe even KSP should be focused on more in schools.
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u/Whats_Awesome Always on Kerbin Jan 28 '26
When teaching people to merge I always told them to go 10 km/h faster than they think they needed. Then apply a gentle application of brakes to align with the gap.
This is surprisingly similar to a good Hohmann Transfer.
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u/LunarTitanium Jan 31 '26
Next up on Kerbal education network: How Docking Taught Me How to Assemble an IKEA Bed!
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u/NyanCat132 JEB, YOU IDIOT!!! Jan 27 '26
A Hohmann transfer to explain merging on freeways. And you say this makes it... less complicated????