Author Topic: Totally crazy idea: Space launch site on Mt Kilimanjaro?  (Read 25683 times)

Offline aquanaut99

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OK, first of all, I know this is totally crazy and politically impossible (and the technical challenges would be daunting as well), but what level of performance improvement could be expected from current launch vehicles if they were launched from the summit of Mount Kilimanjaro in Africa?

IIRC, that was actually proposed by some SF writer (Clarke?) back in the 1950s.

Mount Kilimanjaro is almost on the equator (3 degrees South) and is 19'341 ft (5'895 m) high. Being a volcano, it also has a rather gentle slope which could make the construction of roads and tracks up to the summit possible, as well as a large caldera (several in fact) which could be paved for the launch platforms. And it is inactive.

What performance improvement would a Falcon 9, for example, have if launched from such a launch site, nearly 20'000 ft up?
« Last Edit: 02/21/2011 04:45 PM by aquanaut99 »

Offline TyMoore

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #1 on: 02/21/2011 05:46 PM »
Probably not enough to warrant the additional expense and complexity of building from scratch an entire launch complex and associated infrastructure at 19000 feet! Remember anything over 14000 feet, and people typically acclimated to sea level will need supplemental oxygen. Add to that the fact that most construction equipment isn't designed to operate at that altitude so things like diesel generators, excavators and dump trucks will need specially modified engine systems to be able to start at altitude. Add to that the necessary road construction project from a base camp. Probably a rail line from the coast. A port facility. A concrete plant nearby. Oh yeah, and naval security forces for expected merchant marine traffic that will of necessity pass nearby the Somali coast line.

And then there is the political situation in nearby Kenya, not as stable as it once was. No doubt certain 'gratuities' to certain officials may be needed to catalyze and maintain the whole effort.

And then there is the environmental red tape from building in a protected area in Tanzania.

And then there is the fact that there are glaciers and volcanic scoria that you are trying to build all this on...neither of which is very structurally stable: bed rock is only about five miles down, so pilings are probably are not an option either.

And then, if that wasn't enough, Kilimanjaro is still active. Not very active, but active is active in my book.

Billions and billions of $$$$

Still think it is worth the performance gains?
« Last Edit: 02/21/2011 06:00 PM by TyMoore »

Offline Lee Jay

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #2 on: 02/21/2011 06:15 PM »
What performance improvement would a Falcon 9, for example, have if launched from such a launch site, nearly 20'000 ft up?

Something like a few percent.

Offline aquanaut99

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #3 on: 02/21/2011 07:44 PM »
Still think it is worth the performance gains?

Thanks for your answer. No, I do not think it is worth it (and I didn't to begin with). I also know all about the technical and political problems, that's why I said it's a crazy idea. I was just wondering.

Offline malenfant

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #4 on: 02/21/2011 08:35 PM »
If politics were no issue then somewhere on the Somali coast would probably make more sense.  Watch out for space pirates though.

Offline extide

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #5 on: 02/21/2011 09:30 PM »
Most of the fuel used to get to orbit isnt used to go UP but to increase the velocity in the orbital direction. Remember, for example, ISS travels at ~17,500 mph, and you still need to get going that fast in the horizontal direction regardless of how high up you launch from. There will be a bit of a boost because of the increased radius of the earth at that point but that alone would probably be less than one percent.

Offline gospacex

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #6 on: 02/22/2011 02:14 AM »
Most of the fuel used to get to orbit isnt used to go UP but to increase the velocity in the orbital direction.

Most people on the forum know this already. 5km+ altitude does provide advantages of lower pressure - this allows more efficient nozzles on 1st stage.

The biggest problem with this proposal is that Tanzania is not Germany :) Doing business in 3rd world countries is PITA even at the sea level.

Offline Stephan

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #7 on: 02/22/2011 08:42 AM »
And DeltaV penalty due to atmospheric drag is marginal compared to gravitational losses.
Best regards, Stephan

Offline suncity

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #8 on: 02/22/2011 01:18 PM »
I think it would be interesting to have a numerical answer to this question, both for fun and to get a better perspective on the factors involved in launches. Without forgetting of course that Africa would be a challenging base of operations...

My 2 cents:

- the altitude of 5895 mt is equivalent (I think) to a delta V of 340 m/s, which is about 4,4% of orbital velocity

- Being at 3° from the Equator compared to 28° of KSC shoud add 56 m/s to the initial velocity, an additional 0,7% of orbital velocity

- I don't know how to quickly compute the effect of improved ISP from launching at altitude; but considering that atmosferic pressure is about 1/2 at that altitude and that ISp improves with altitude it should be possible to get an estimate of performance improvement. As an exemple, SSME ISP changes from 363 sec at sea level to 452 sec in vacuum (according to Wikipedia).
This improvement exists with unmodified engines, but would be even larger with a noozle extension optimized for starting the engine at 1/2 of sea level pressure.   

 
« Last Edit: 02/22/2011 02:21 PM by suncity »

Offline Wayne Hale

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #9 on: 02/23/2011 01:47 PM »
There is a common misconception that launching from a high place is important.  If you look at the amount of energy required (kinetic and potential) to achieve earth orbit, the kinetic part far outweighs the potential -- in other words it is more important to have speed than altitude by an order of magnitude.  High altitude launch sites have severe logistical problems (as noted by earlier comments).  So it is unlikely that launching from high mountain tops will ever realistically be practiced.  However, launching from locations near the equator have some advantages; the Ariane launch site in Guyana is a good example; as it the Kwajelein launch site originally used by SpaceX.  However, remote sites (like Kwaj) also have severe logistical problems which can reduce their effectiveness.  And for planetary missions or high inclination missions (as to the ISS), being near the equator has no advantage.  As it turns out the best launch sites have great logistical advantages - like KSC where there are long runways, rail access, great highways, and oceangoing barge access.

Offline madscientist197

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #10 on: 02/24/2011 07:39 AM »
TBH I find the idea of desecrating Kilimanjaro like this quite offensive. You end up with an obscene amount of irreversible environmental damage for very little gain.
John

Offline hkultala

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #11 on: 12/19/2014 08:15 AM »
One thing neglected in most of the answers is the ability to use bigger nozzle.

The air pressure is so low(half of sea level) in kilimanjaro that bigger nozzle could be used.

This would easily increase the isp(and thrust) of the first stage by some 2-5%, though it would also increase the weight of the engines, and this would not work with falcon 9 because there would not be physical space for the nozzles.

But for example Delta IV or Angara which have only one single-chamber engine per core could use much bigger nozzle.

How much more would RS-68 weight if going from expansion ratio of 1:21 to something like 1:40 ?
Or how much more would RD-191 weight of going from expansion ratio 1:37 to something like 1:60 ?
And how much would the isp increase be in these cases?
« Last Edit: 12/19/2014 08:38 AM by hkultala »

Offline pagheca

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #12 on: 12/19/2014 08:24 AM »
Just a question: isn't launching from the bottom of a caldera potentially dangerous because of noise resonance (echo)?

I seem to remember this was a major issue for selecting Vandenberg or some other launch site in the past. Is it still an issue or not?

Offline hkultala

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #13 on: 12/19/2014 08:27 AM »
Most of the fuel used to get to orbit isnt used to go UP but to increase the velocity in the orbital direction. Remember, for example, ISS travels at ~17,500 mph, and you still need to get going that fast in the horizontal direction regardless of how high up you launch from. There will be a bit of a boost because of the increased radius of the earth at that point but that alone would probably be less than one percent.

But when you start from higher, you can start going horizontally earlier.

The first kilometers after liftoff are the most expensive ones. Cannot go fast due aerodynamic drag, have to rise above the dense atmosphere as quickly as possible.

When launched form higher, athmospheric drag will be much lower and gravity turn can be started earlier. Savings on both atmospheric and gravity losses.

And then the effect of ability to use better nozzles.

The "increased radius of the earth" effect is in the class of 0.02 %, so totally insignificant.

Offline john smith 19

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #14 on: 12/19/2014 01:14 PM »
OK I'll bite.

The rough rule of thumb is atmospheric pressure at 5600m is 1/2 that at SL and nozzles can expand down to 40% of ambient before flow separation effects become severe.

Likewise an equatorial launch site buys you about 340m/s.

So you can slap a much bigger nozzle on the engines (pretty much the default move when management calls for more Isp) and you get higher starting velocity launching East than at around 28deg of US launch sites. It's close to Mach 1, which is still only 1/23 of orbital velocity (neglecting any losses) but not to be sniffed at if you have to get it by burning propellant.

But $deity what a PITA  :(. There's a pretty major tourist business that's going to take a beating. I'm guessing the local tribal elders will be more than a bit miffed and the hardware is coming several 1000 more Km's to get there.

If you want performance at any price then Somali is the choice geography wise in Africa.

BTW It's not often realized that the Italians launched a few Scout solids off the African coasts in the 1960's. It's near "Malindi" in Kenya.

http://en.wikipedia.org/wiki/Broglio_Space_Centre

TBF In terms of up and running site Kourou has a lot going for it. 
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline Danderman

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #15 on: 12/19/2014 02:02 PM »
We need Mike Heney to tell us about a better site in South America.

Offline Proponent

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #16 on: 12/19/2014 02:36 PM »
OTRAG launched a few rockets in the 1970s from the Congo, though it never achieved its orbital ambitions.  I imagine that the very low-tech nature of OTRAG's rockets meant that it was relatively insensitive to the quantity and quality of the available infrastructure.

Offline dchill

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #17 on: 12/19/2014 04:30 PM »
We need Mike Heney to tell us about a better site in South America.

Do you mean this inactive volcano peak in Equador?
"The highest mountain on earth is Mt. Everest in Nepal at 29,029 feet above sea level. However, it not the point on earth that is farthest from the center of the planet. That honor belongs to the volcano called Chimborazo in Ecuador."
<<http://en.wikipedia.org/wiki/Chimborazo>>

Obviously there would be logistical issues.

Offline fast

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #18 on: 12/19/2014 05:07 PM »
Must be the best place on earth for SSTO launch :)

Offline R7

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Re: Totally crazy idea: Space launch site on Mt Kilimanjaro?
« Reply #19 on: 12/19/2014 05:28 PM »
Must be the best place on earth for SSTO launch :)

The NE/E/SE neighboring countries might not like the risk from those launches at all. Plus all the prementioned reasons.
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