Does Launching Rockets From A Mountain Really Help?
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- Опубликовано: 9 фев 2025
- I've been asked this question in the past and using kerbal space program's Realism overhaul allows me to demonstrate this, since there are multiple factors involved.
I also wanted to show off the new Realism overhaul which was released last month for KSP v 1.2.2 along with a working visuals upgrade. KSP 1.2.2 is a slightly older version, but, the main focus of 1.3 was adding languages rather than features.
CKAN:
github.com/KSP...
RSS Visual Enhancements:
forum.kerbalspa...
And you need the 0.03 version of Scatterer (don't install scatterer via CKAN).
spacedock.info...
I propose we call the mountain in question a Solid Rock Booster.
AgentTasmania Yea
The greatest comment in history...today. :P
That is one of the best puns I've seen in quite a while.
KDreezy Gaming That is one of the best comment of the best puns I've seen today.
You have officially won the Internet for me today
"Everest station, we reached 4Km, launching 2nd stage sherpa in 3... 2... 1... "
A booster rocket called a sherpa would actually be a damn clever name for one.
you forgot the very smallest benefit when listing the benefits of launching from a mountain: more initial orbital speed
since you are further from the earth's center, you are traveling a slightly greater distance each day than you would be at sea level. this is easily the smallest benefit and is hardly even worth calculating for
Don't forget that less distance to target orbit means less time in flight before breaking into orbit, which means less gravity drag (Scott only mentioned starting where gravity is less strong, not time experiencing gravity drag).
also: when you launch from 8km up you only have 92km to go to reach the Karman line
Chalk Chalkson that's the same as having a lower atmospheric density, which is the strongest benefit that he already mentioned.
There is other advantages to with air launch.. he kind of touched it.. but not quite.
With air launch one can launch closer to the equator.
Also... with air launch. A aircraft is much simpler to maintain than a launch pad.A aircaft is just a aircraft. Can pretty simply dropp away the rocket 100 meter or so before it ignite the engine, having no problem with the heat.
So i don´t really agree with scot there... Also proven to be kind of true with space X having quite a lot of problem with there launch platform that they just would not have other vice.
That's a larger advantage for air launches. Surface velocity is only about 1650 kph. You'd have more trouble finding a modern aircraft that can't add an appreciable fraction to that by flying East than one that can. The gap between the surface speeds of Cape Canaveral and Korou is about 13%. Launching from a modified Boeing 777 would be about a 54% increase in lateral velocity compared to an equatorial surface launch on top of the engine efficiency advantages of launching at approximately 13 km altitude. Between the relative ease of recovery of such a first stage and the lack of need for oxidizer it's hard to dismiss the notion.
08:00 "good realism overhaul" *rocket bounces*
Forget big lumbering planes! I say we strap the rocket to another rocket. It's brilliant! Nothing else can lift that sucker up to a good starting-off point like a powerful rocket can.
wait a minute...
That would be called a strap-on booster rocket. You know, those things on the sides of rockets like the space shuttle.
@@bfhammer no its called stage 1
they're also called "solid rocket booster" not "strap on booster rocket" that sounds like a sex toy
@@anuclearpan4554 Unless it is a Russian rocket. They don't use solid propellant, so by definition it cannot be called a SRB or Solid Rocket Booster. Or a SpaceX Falcon. Again, a liquid-fueled booster strapped on to the sides. Cannot call it a SRB by definition. NASA themselves have historically used the term "strap-on booster" on occasion. Get your mind out of the gutter.
@@anuclearpan4554
Strap on rocket boosters compliment rocket boostiers. What's a rocket boostier? It's a rocket stage with a built-in decoupler. It lifts and separates!
Why don't we launch all our rockets from Antarctica? Then you just let them fall into space, you don't even need to use the engine for takeoff.
because you can do the same in Australia
rocket just falls from the Earth into space
You mean we just drop them from the edge? Thats genious! :O
you are wrong, the rocket will just roll down to japan, and only then it will fall
I don't know if you are being sarcastic or not, but that would not have any change in delta V needed to get into orbit. Plus, you would not be able to go into an orbit which is not polar efficiently, which is why real rockets are launched at equator :)
Because it would be so much harder to orbit the equator. And any orbital inclination, especially one from Antarctica, take more juice to achieve orbiy
I would love a series of mod installation tutorials, especially for more complicated instals such as realism overhaul. For someone who loves the game but has no idea what they're doing with mods, it would help tremendously!
Amazing, I had kind of been avoiding the realism overhaul because I was under the impression it was a long procedure. Thank you for the tip and also the idea of having a second install for the realism modded version.
The other thing that isn't easy is running Realism Overall on a 2 year old budget laptop.
HAHAHHAH i have a fucking mac :{
Aron Thomas 13 year old piece of shit here
@Mine Miner
Goodness I thought my Toshiba a100 (which still runs fine as my backup computer) was old.
What is yours?
LdaQuirm A HP xw4300 workstation. Not the best PC to have, as I have to use Photoshop and edit videos regularily. But next year I am going to invest, not in another Bike but in a nice PC. The jump from 2gb ddr2 to 32gb ddr4 will be awesome :D
6 dollars a day at a Starbucks or a Fast food joint adds up to more than $2000.00 in a year, if you adjust some of your living habits you could have a nice computer capable of playing modern games.
Scott: casually lands on titan
Me: How do you get to other planets other than minimus and the mun plz help
Look up the mod Transfer Window Planner, that will get your phase angles sorted and even gives you a handy dV estimate for any given launch day. From there it's the same old transfer like you would use to get to the Mun, just... more.
Start with Duna, it's fairly forgiving with its aerobrakes and you still have to use rocket motors to descent. From there the whole system is at your fingertips.
Well, he may or may not have cheated.. A bit.. ;)
Stop misspelling Minmus for starters could help. Watch closely: Min...mus. Min...mus. There is no fucking second i in there.
This is a mod that adds our solar system
Minmus and Mun aren't even planets lol, they're moons. I managed to get to Eve once, but only one way.
starting from 8km above sea level, you'd also gain additional 0.5 m/s orbital velocity from earths rotation, although that's only a 0.1% increase to the 465.1m/s you get at sea level anyway.
For a SSTO a mountain launch might be better since you can get away with bigger engine nozzle due to the lower air pressure, which would result into less over expanding in space.
Just use bell noozle
I love these types of videos, Scott; where you domonstrate/test/explain rocket science and phyics with KSP. Very interesting to me as an Engineer.
A few years ago i did the same using some balloon mod. was fun to use a 'flying launchpad'.
You should've recorded that, because this sounds interesting.
We need an alternate reality where Somalia and Ethiopia hadn't gone for war over Ogaden region and where it is a place of soviet launch site right on equator and almost 1.5 km above sea level:D
As a Somali that'd be really interesting, though I am only 12. That would be a really good launch site.
And a possible detterent from actually fighting in a region for as long as cosmodrome stood as well as a source of further investments in region's infrastructure.
Definetly far better than flooding the whole region with weaponry and expecting everything to go great from that point onwards like our goverment did in reality...
Is there a new fad where young people spontaneously write down their age in the middle of sentences with literally no context or something? I'm 9
Dominic There's context and reason, Because such a Cosmodrome likely would've fell into disuse after the fall of the Soviet Union and thus due to his Age he would've only grown up with the stories, and the benefits it would've given, in any case he's too young (as am I btw and i'm like twice his age) to have lived while the Soviet Union existed
Best scott manley quote: "look! It's totally (functional, working, etc.)
Actually the biggest factor, and one you did not mention would be the outside air pressure would be lower which in turn would actually allow you to have a rocket engine bell that is optimised for a lower external air pressure allowing a more efficient combustion bell nozzle to be used
As I have proposed on several of these videos - lay the rocket stack over on the side on a maglev sled up on a mountain plateau, accelerate the sled over several miles and up the side of the mountain, snub the sled at the top and fire the engines. You have less airdrag, tiny bit of less gravity, and significant forward velocity at engine start. This will put a good size dent in the amount of fuel per pound of mass lifted to orbit.
God damn you South Africa, the entire Highveld is over 1500m ASL. Where's our bloody space program!
God damn you Ecuador, you have the highest point of the planet, the highest capital of the world and are located at the equator. Where's our bloody space program!
braeddie they actually had a space program first 6 months but was disbanded because it was unconventional
+starmax1000 Who knew that Mnt. Everest was in Ecuador?
it's Chimborazo... look it up, due to the earth's rotation the planet bulges outwards and that makes it just taller than Everest.
braeddie South Africa? Think you meant "Spis Pragrehm".
Some other advantages could be the fact that you can design the nozzle bell a little longer adding even more Isp and you can shape your trajectory to be more sharp with a faster turn reducing gravity drag.
Also if someone is asking what could be the best site to launch a rocket (political and economical factors aside) I found a pretty spot on a plateau of 20Km radius in Kenya near mt Kenya: 3200m of altitude and almost dead on the equator. Relatively near the Nairobi airport and lake Victoria to the west and the sea to the est. Also near the only semi desertic equatorial region so weather is quite clement there.
nice, but isnt it too far away?
redbeam_ well depends from where you start.
Secondly I did not said it's the best place for launching rockets, just the high place most close to the equator, any economical and logistical factors aside.
Kenyan Space Program when?
I like the choice of "lob" for the verb to describe bringing a payload into space.
That sound of the RS-25 igniting..... is beautiful.
Always had a dream of propelling cargo to space utilizing a mountain and a - U - shaped mass driver. The cargo goes down the rail from the top of the mountain utilizing earth gravity for the momentum velocity and the mas driver magnets for further velocity.
Lord Zephyros THAT WAS MY IDEA
oh, im glad im not the only one! :)
The going down part won't help much. You could use the energy used to lift the cargo to the top of the mountain to accelerate faster and the material to make the rail taller. But air drag would kill it anyway. An hyper loop tall enough tho...
aaaaand the cargo would be vaporized in the process, we are talking going with orbital speeds in dense parts of atmosphere.
randomnickify it depend's of the material
Great explanation of the installation process for mods.
There are a number of advantages not listed here that would apply to an air-launched rocket. Not that I'm arguing it's more practical, but he's skipped a few.
1. Your initial booster can be tuned for a lower air pressure - basically you can START with vacuum engines if you're launching from 10k up. So instead of using an expensive RS-25, you can start with a cheaper J-2X.
2. You can use a higher initial TWR, and do it without having to have throttable engines. This means you can avoid more gravity losses.
3. You can start out flying at an angle. Most rockets now are built for an initial TWR of 1.2 to 1.4, meaning they take LARGE gravity losses getting up to 10km, you could avoid most of that by air launching a rocket from a plane in a 30 degree climb. With an initial TWR of 2, you can start flying at a 45 degree angle, and get as much vertical acceleration as a rocket with a TWR of 1.4 and also get a lot of horizontal acceleration.
4. You can build your rockets frame for a lower max Q, saving on dry mass. The space shuttle, for instance, experiences max Q at 11km - they dialed their engines BACK to 60-70% to limit the aerodynamic pressure - which actually meant they incurred yet more gravity losses. If you're launching over 10km to start with, you'll experience a lower max Q at a higher altitude.
Overall, you could save 500-700 meters worth of Dv from gravity losses alone - which, while it doesn't sound like a lot, means that your rocket can be 18 to 26% lighter (assuming a kerolox initial stage with an ISP of ~300). I'm not qualified to estimate the gains from a lower max Q and and lower drag losses, but even just from that, I call BS on Elon's number - or at least, he's estimating his 5% against the total Dv needed, which is slanting how people understand the costs.
Paul Boyle your right man
Paul Boyle yeah, you save 700 m/s of dv which actually triples your payload. Elon is just an obtuse fuck who knows jack shit tbh, i could quote him again and again with dumb, factually wrong statements. Thr proof of that air launch really does give a huge advantage is the Pegasus and Taurus rocket, same payload, but one is 2.5 times smaller. And thats from Antonio Elias, designer of Pegasus
Less vertical distance means less thrust needed, which means less fuel needed, which means less mass, which means less thrust etc. For e.g. If commercial jet planes took off from the top of Everest, they would use ~30% less fuel because the engines would be smaller and the fuel mass would also be smaller.
You can also time your airborne launches (provided a rendezvous is not required) based on upper air soundings!
A pro-grade launch from the east coast of the US wherein the orbital inclination = the air launch latitude can coincide with a STRONG upper atmosphere jet stream.
I have personally witnessed jet stream velocities on the order of 160 kts (300 km/hr) in the wintertime from the west. Combined with an aircraft cruising at FL350 at Mach 0.84 (normal cruise in 747), you are starting with a Groundspeed of well over Mach 1....or roughly 640 kts. For the metric system fans, this is 330 m/s of additional initial orbital velocity (in addition to the free orbital velocity provided by the earth’s rotation.
Ian Thompson
One factor looms large though with aircraft and high elevation runways. It’s easy to forget when thinking about rockets, but airplane wings (and the tiny wings of the engine fan blades) depend on air density, airspeed and angle of attack to create lift.
With Pressure altitudes on the order of Mount Everest, for a mid size jet like a Boeing 737 at a modest takeoff weight, it would require a runway roughly 3 miles long. Also, to achieve the INDICATED airspeed to rotate to takeoff pitch attitude, the TRUE airspeed (and therefore the GROUNDSPEED ...assuming zero wind) would well exceed the published groundspeed limits for the tires!
For those reasons, most commercial airliners have 8000 or 10000ft as the limits for departure and arrival airport elevations.
Also, the IAS and TAS / Mach difference, limit our flap extension altitude to 20000ft. The greater curvature of the wing with flaps deployed will cause local Mach shockwaves on the wing at relatively low indicated air speeds when flying at high altitude.
Interesting thought experiment though.
There is another small advantage to launching from a mountain: no salt spray, meaning potentially lower maintenance costs
you would still have to get the rocket onto the mountain... I imagine that you would use more fuel to get the rocket up the mountain rather than just starting from the ground
Austin Vette Bring the rockets in parts on top of trucks, which travel through a low incline road spiralling up to the summit. Then assemble at the top
builds a few more miles inland...
What about higher wind speeds, there would be a much smaller launch window and bad weather conditions on mountains are much worse than on the ground.
@@spacedoutorca4550 oof good point
5:16 This is one of the reasons we have multistage rockets - - the first stages use a slow burning fuel to take the upper stages to high altitude at subsonic velocity, eliminating most of the negative effects of air drag and cavitation
Whoop! I've been waiting for realism overhaul to catch up :)
I got a challenge: play on 12 FPS.
It's so freaking haaaaarrddddd!
Because when you click W A S or D it moves like 5 seconds after I'm screen, and you don't see that much going on.
And then land on Duna.
I have an average of 1 fps
Scott Manley, you forgot the most obvious advantage of launching from a mountain: the added height. Denver is a mile high. A two mile high mountain launch point would cost a lot to transport but it not only adds 2 miles to the potential launch altitude but adds the other benefits you mentioned and could add more miles too.
4:27 "Mt." Chimborazo is actually a volcano... tallest point from the center of the earth... although getting there is easy (as an ecuadorean I confirm) the climb is way too steep to put a launch site up there, plus it destroys the natural and untouched look o the place. oh right there's also a very slim chance of it erupting too! :D
starmax1000 Bah, erupting volcano just means extra dV
Who needs a gravity assist when you got a volcanic assist
And earthquakes may be
Shouldn't there be two more advantages of launching from a mountain?
1. Shorter vertical distance to the desired orbit.
2. Higher horizontal launch (orbital) speed thanks to being further from the planet's rotational axle. (Starting from a high top in for example Ecuador should give a great horizontal push.)
Yes. Thank you for saying this. I've always said that I have doubts about air launch because it really doesn't gain you that much, but nobody really believed me.
Well, launching from a suspended position 1k above the floor and launching from solid ground at 1k should by all rights yield completely different results.
In the real world realm, I'd love to hear your views on electromagnetic catapults as described in Heinlein's //The Moon is a Harsh Mistress// where the Lunar delegation was trying to interest various countries in building such, using a high mountain with a long ridge to the west (and hopefully ocean to the east for failures and aborts).
The launch height at 2:48 is higher than the Burj Khalifa
I like how the booster smashing into the coastline at 900m/s caused less damage than the booster smacking said coastline at 30 m/s
Without having watched the entire video I would say the biggest problem with this is now all the supplies,and buildings have to be transported to the top of this mountain for it to benefit not to mention the cold weather might become problematic (consider the challenger explosion) It would be less costly to launch from sea level on a flat.
I'd like to see an analysis of launching from a very deep underground "silo" that would use a system of 3 linear motors that would propel lifting points on 3 sides of the rocket to give it a "launch assist". It seems like so much fuel is used to just get the rocket moving that a launch assist mechanism that could give it an initial push upwards of even 100 Kph could save many tonnes of fuel.
You did illustrate this once before with that super ridiculous RCS thruster rocket.
Scott you need to do a new series of RSS + RP0 + RVE!!! I could watch those for hours!!
I missed your videos like this.
Additional advantage: engine nozzles are tuned to work most efficiently at one altitude. Because the engine is not used to elevate the rocket up the mountain, that inefficiency in the engine's power band is not used. It's a bit like starting a drag race at 3000 rpm instead of idle. I learned this from Scott Manley - he has a video on rocket nozzles that is quite good.
I just watched a 5 min ad from the black buzz feed because it's a funny vid and I want you to get that ad revenue
One more advantage to launching at high altitude is the reduced or eliminated need to throttle back for max Q and not having to throttle back improves efficiency.
Mt. Chimborazo makes so much sense. It's right on the equator and is actually higher above the center of Earth than Everest is. Build a linear accelerator up the west side of it that releases the rocket stack when it reaches the top!
I think theoretically someplace in the Andes near the equator would probably be a really good place for an optimal launch. Decent amount of flat high altitude places, decent transportation to the potential launch site, close proximity to equator. It might not get too much benefit but a more optimal.
I often thought about this, if were to become better at launching things into space, why not build a permanent mag rail up the side of a mountain. Initial Momentum can be provided and powered on the earth as opposed relying 100% on rocket motors.
These Scott Manley videos are SOOOOO G.D. interesting! And delivered with a tad more credibility than TMZ or People Magazine :)
Here's a thought, Scott; With developments in railgun and energy storage (in-particular, ultracapacitors) technologies, would it not be possible- even desirable- to launch a vehicle from a mountain-bored verticle tube with assisting kinetic energy being supplied by a railgun launcher? This could give a vehicle an initial thrust to, say, just short of mach 1 by the time it reaches the mouth of the launch tube where onboard thrust would then be ignited to take the vehicle the rest of the way to space.
You could gain acceleration most of the way to mach 1 without burning a drop of onboard fuel. At which point your vehicle could be at or close to 10,000ft in altitude. By igniting the onboard engines just seconds before leaving the tube, you eliminate concerns over excess pressures in the confined space of the tube, as there is now a column of air beneath the vehicle that can act as a pressure buffer.
Moana Kea in Hawaii would be a perfect contender for such a system!
love your videos. they really bring out the scientist in all of us
You should do a video explaining why it's more efficient launching a rocket on the equator. you could also fit in some atmospheric science too. :P
because earth isnt a perfect sphere and the earth bulges at the equator, so it's higher up so less gravity (and possibly air resistance) and less fuel needed for the same velocity, or in other words, this video but with the equator instead of mountains.
short version, you're moving faster so require less dV to get to orbital velocity
Add that to the mountain launch. Let's build a launch site in Peru.
Corey Newhard that is not really true, earth is just 0.3% bigger on the equator. for comparison, a official billiard ball can't deviate more than 0.1%. so earth is pretty damn spherical...
the reason its better to launch at the equator is because the rotation of the earth give an extra boost to the rocket speed, its not much, but it helps.
the biggest reason is that you can get into a "flat" orbit without a plane change.
More important than gravity reduction is increase in angular momentum. In the extreme case, we are talking about space elevator, the dV cost of launching from which is zero. But a tall mountain helps as well. Not nearly as much as pressure drop, but far more than gravity reduction.
Combine a high altitude launch site with being close to the equator and using some type of ground based boost system and there could be significant efficiency gains. For the ground boost it could be a cold gas assist, rocket sled, or EMALS like catapult to launch it straight up or at a slight angle towards orbit heading.
Here's a random question - what if you have a mechanical propulsion mechanism to help you get some initial speed to help out the first stage of the rocket? Imagine a massive structure going 1 or 2 km deep into the ground and propelling your rocket towards the sky(let's leave the implications of building and maintaining such a beast aside).
Now, obviously this will still cost you a lot of energy, but would it be able to give your rocket enough momentum to the point where you'd need less fuel for the same payload? From what I understand(and correct me if I'm wrong), currently a big limiting factor in space exploration is that the bigger payload you want to send, the bigger your rocket has to be and that grows exponentially(they payload / mass ratio is very very small). So, if we can convert some of the fuel weight to payload weight, then it'd be a win, no?
As a Heinlein fan, I know that you need a mountain in order to build a linear accelerator up its side, your rocket only fires once it clears the launch rings.
Dear Scott Manley,
I was always wondering, why the flight parabola/curve always shift west in ksp no matter how straight you launch up? Is it because the turning of Kerbin? I thought so at first, however after closer investigation of the map screen, i noticed that the flight curve does not move with the turning of the planet, so that if the flight curve was curving westward because of earth rotation, then they would calculate that twice.
If im wrong please correct me.
Kind regards
Koso - craft / GermanLeagueGaming
I believe there is less drag when launching west, because the atmosphere is moving with the rotation of tha planet, and the slight speed gain. I may be wrong though.
Might be it.
It's called the Coriolis effect. As the planet is spinning east, an upward motion produces an acceleration due west.
SAT1URN . This is actually my second account and i made it (the profile pic) 6 years ago. Just to lazy to change to the other one and do all subscriptions and stuff.
Hi this is the second account
I love space stuff so much!
Actually, you are using an engine designed for sea level launch at half a mile up...
What if you could use an engine designed for launch at 1 mile up? Your engine wouldn't be underexpanded at launch and you would actually gain even more efficiency. Stratolauncher (a bad design) would still benefit bc the engines would be designed to be ignited at altitude.
The main advantage to launching from a mountain is that any aquifer would be farther below the surface, so you don't have as much of a problem when digging out the massive hole for the moon cannon.
Thanx, Scott! I am just reading a book about the Chinese Space program and was wondering if XiChang's height would make it easier to launch into higher orbits. I really love your videos and explanations! Thanx for all your hard work!
Do you recommend the book?
Title, please, if you do.
THE PLUME LOOKS AWESOME!!!!
Hi Scott. You discussed differences in launch altitudes as basically sea level versus mountain top, and differences in associated air density, but you didn't discuss other associated aspects of 'height' such as distance above the centre of the Earth where the surface of the Earth on the equator is 21.15km (13.14 mi) "higher" than the poles. Do you have a video on this or could you address this. I would also be interested in any comments on "effective" gravity differences between the equator and poles and the implications for rocket launches. Thanks, Jim
launching at high altitude also means you can design different rocket nozzles that are more efficient for the new flight profile.
Slightly related: Just saw a meteor with a long (but not very bright) tail break up in four or five pieces that quickly burned up. First time I saw that with my own eyes. Nice orange fireworks.
It travelled in NE-erly direction and passed between 'Altair' and 'Deneb El Okab' in what looked like a shallow dive.
This happened while I walked the dog immediately after watching this episode. So therefore "slightly related".
Best launch site would be Mt Chimborazo in Equador. Elevation of over 20k feet and within 2 degrees of the equator. Have the first stage be a railgun on the side of the mountain that launches the rocket at mach 7 and you can cut the cost of putting things in orbit by a significant fraction.
The main issue is the logistics of getting your rocket there in the first place.
You have to understand that the difference between launching from a mountain versus launching from sea level is that sea level is usually (but not always) you know, pretty damn close to the sea and huge bodies of cushiony water for recovering that which can be recovered and disposing of that which cannot be recovered safely in the event of an accident. And while mountain can be remote, that remoteness invariably means it’s that much harder to get the rocket parts to the pad
Another variable on overall benefit, you may save some money by being more efficient after launch, but building a launch pad and shipping all required things to the top of a mountain may cost more than you saved. Tends to be tough and expensive to build on and ship to the top of a mountain.
What about the advantages of:
1. Larger lever arm
2. Less distance to fly
(Let’s launch off Everest)
The C5 Galaxy was designed with rocket launches in mind and was tested a few times.
Willing to bet the people asking weren't considering specific impulse, gravity or drag, but simply "if I'm on a 1km tall mountain, I can fly 1km higher" ;)
That said, you have to get the rocket onto the mountain in the first place. Most reasonable people wouldn't use a rocket for this, but physics says there is a minimum energy requirement for it, be it with a truck, or a crane
Yep, the chinese launch sites weren't chosen because they were a mile high, they were chosen because they were in the middle of the country and remote enough not to be easily vulnerable to attack.
What is specific impulse, I know the rest but what is it?
How efficient your engine is. The higher your specific impulse, the more deltaV you get from the same amount of fuel.
Ok thanks!
In very simple terms, it's the impulse (change in momentum) created by a set amount of fuel. Basically, the more impulse you can get from each drop of fuel, the more efficient it is, and the higher the specific impulse. I'm sure there are some good videos on this channel if you want a better explanation than I can give
Scott got it wrong. There are FOUR factors that give an advantage from launching at altitude.
1) increased specific impulse from less atmospheric pressure
2) reduced aerodynamic drag from less atmospheric pressure
3) reduced gravitational force from being father from center of gravity
4) less distance to travel since higher elevation is closer to space!
The Andes will be a great place to launch. Higher up & on the equator.
8:01 wow! This thing syrvived 800 m/s impact!
Yet, not the 18m/s one
You know, I agree with you, it really /is/ pretty embarrassing that every single planet in the Kerbal universe rotates on the same axis.
Now the question is this: if the goal is to launch into an equatorial orbit, is it more advantageous to launch from a high elevation site located in a middle latitude, or from a sea-level site at an equatorial latitude? And what if the goal is to launch into a polar orbit? Or something in between? What if the goal is to launch into an interplanetary transfer trajectory?
What we really want is a magnetic launch tunnel inside a high mountain on an eastern coastline...
Fortunately Papua New Guinea has a 4 km mountain close to its pacific coast, with a deep valley almost down to sea level nearby for easy access. Not only that, but New Guinea is really close to the equator.
Thats nonsense cause of frequent Earthquakes.
Where the Nasca lines are located at in Peru. Up in the Mountains it looks like they cut off the Mountain tops to make run ways. Is that an ideal Launching Site?
What about on a mountain, using a launch slope up the mountain with a powered sled to add velocity without having to have on board fuel thus lowering launch weight.
You add that speed in the wrong direction.
Coastal site?
Let's say you chose to establish a launch site near the observatories on Moana Kea in Hawaii. That is an altitude increase of about 4200 meters. Much better than the launch site in China.
The site has an industrial access road and is near sea ports and airports for logistics support. Being closer to the Equator at about 20 deg N, the surface speed is approx 1575 km/h (about one extra km/h added from being at mountain altitude.)
In addition to the high elevation, a launch site located there would benefit from the dry environment and stable airflow, placing the rocket about 40% of the Earth's atmosphere in terms of altitude. While there are some challenges for human workers due to thin air, it is still within the range that allows for routine operations.
There is a small reduction in the force of gravity, as mentioned in the video. The island launch site would allow for a large range of launch azimuths.
The major issue for this location would be local opposition to development on a sacred site, as well as launch near/over population areas.
Launch from Mt. Chimborazo in Equador. You get near max velocity from the rotation of the earth (say 450 m/s), also 6,263 meters of elevation. Add in a linear accelerator up the side of the mountain. With 4g acceleration (which should be ok for most healthy people), you could get about 700m/s additional velocity, for a total Vo of 1150 m/s. Yes, it would be very difficult, and expensive, but if you want to launch the sort of volume of rockets Musk is talking about it would likely yield some significant long-term savings. Note that Unmanned missions could accelerate at a much higher g force on the linear accelerator, probably at least 10g. So they would get an even higher Vo.
1:50 The fact that you're closer to space doesn't make a difference?
Closeness is not important, speed is.
If the mountain had an height of 35,786km, then any object on top of it, would already be in orbit :-)
one more advantage of launching off an mountain is that you are higher up meaning less distance to travel
I propose Mount Kenia. Close to equator and 5200m high. And it has a river running all the way to the ocean. You only have to straighten out the river a little and build a ramp to get up the mountain and voila :D
You’re also closer to space when you’re higher up so there’s a 4th advantage.
Bailey Jorgensen also known as having less gravity
Jkl Alskjdjhg No. Even if gravity didn’t change, you would still need less fuel to reach space than you would from the ground.
I've gone to the end of the reccomennded list
Nice to see tha advantages of launchng from Mt Kilimanjaro - 19,000 ft and on the equator. So first 4 miles of altitude are "free" and the full rotational speed of the earth about the first 1000 mph "free" also. Plus of course the thinner air at 19,000 ft. and the oblatness of the earth.
The tech I would like to see examines with serious science and budgets is to use the slope of a mountain as support for a mag-rail "first stage"
I found references to StarTram and a few other programs that don't seem to be going anywhere (pun intended).
Lighter than air craft could be interesting for staging, especially for getting smaller payloads into orbit.
could you try making an rss ssto?
Yes, the RS-25 makes that easy.
Assuming you don't do something silly like put wings on it.
LOL
*cough* Skylon *cough*
+Scott With a proper combination of RS-25 and nuclear engines you can even make interplanetary SSTO although without any payload ( just fuel tank and engines).
Scott...I remember one of my physics profs in college mentioning that there is an advantage to launching orbital vehicles from the lower latitudes, e.g., French Guiana in South America. I don’t recall in detail why. Would you care to take a shot at explaining this, or have you already and I just couldn’t find the video? Thanks in advance.
The surface is moving faster (longer circumference, same 24 hour rotation) at about 1000 mph so you get this added horizontal component to the orbital velocity. Let's hope Scott gives and even better explanation!
George Reynolds Thank you George. I used to know that; it’s been over 30 years since I even really thought about it. I was 3 years into a BS in Physics and changed majors. Anyway the mathematical description I now recall is from the same subset that also includes explaining things like the differential on the rear axle of a car.
You get a much larger benefit by having your launch-site near the equator (low latitudes).
What do you think about the start up called zero2infinity that tries to launch microsatellites after a balloon lifts the payload above the stratosphere?
good video, do you have a video about must have mods for ksp?
if not could you make one?
And you also get the advantage of not needing to power the vehicle up to the start altitude. (especially for these altitude tests)
When I saw the title of the video I calculated the potential energy an object with the mass of a rocket would have on top of a hight mountain, in comparison, the kinetic energy to get to orbital velocity is much higher and the potential energy gain becomes insignificant. Is my thinking right? :D Thank you!
9:04 Kerbal Spaceships Are Serious Business Second Season confirmed!!!!
My guess:
It's because placing the launch sites on mountains makes delivery of the rockets very hard, and that small percentage of more efficiency by putting the rocket on a mountain can be exchanged for a bigger efficiency of the rockets themselves
Would the higher rocket not benefit from also having low ground clearance? Sort of the difference between climbing up a stair to raise yourself and trying to slam your foot down so hard you literally push yourself off the ground from air resistance.
Hey scott! I know this video is about 4 years old, and I'm sure it's a fairly basic explanation, but do you have, or could you do, a video explaining specific impulse and why it changes with altitude?
What are the system requirements for the realism overhaul and visual enhancements ? Also, how does one revert to version 1.2.2?