I think Dale bends over backwards for SLS, but it’s really no contest. I also think that while it’s possible that a mix of the two would be optimal, it’s very unlikely.
5 thoughts on “Comparing Heavy Lifters”
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I think Dale bends over backwards for SLS, but it’s really no contest. I also think that while it’s possible that a mix of the two would be optimal, it’s very unlikely.
Comments are closed.
Pipelauncher for Falcon Heavy
Falcon Heavy:
height: 68.4m 224.4 ft
width: 11.6m 38 ft
total mass: 1,462,836kg 3,225,000 lb
As Compared to Falcon 9:
height: 68.4m 224.4 ft
width: 3.7m12 ft
total mass: 505,846kg 1,115,200 lb
So looking at pipelauncher to launch rocket at +100 mph [45 m/s +]
Minimum distance at 45 m/s and 9 m/s/s acceleration is 5 seconds at 9 m/s/s is 112.5 meter [369 feet].
Suppose pipelauncher is 244 meter [800.5′] tall
And 20 meters [65.6′] in diameter.
The 20 meter diameter per 1 meter length has fresh water displacement of 314.159 tonnes.
As rough guess, mass of pipe.
Assume 1 cm thick pipe walls.
circumference of 62.83 meters. Times by 244 meter length times .01 meter walls gives
volume of aluminum metal. 153.305 cubic meters times aluminum of 2.7 is 414 tons.
So roughly assume mass of pipelauncher to total about 500 tonnes. Or gross weight
including rocket to be 2000 tonnes. Add 200 tonnes for tower and misc.
So needs 2200 / 314.159 which is 7 meters of air below sea level to float. And
14 meter for 1 gee acceleration force.
Pressing water 10 meters under surface requires 14.7 psig. 14 meters is 20.58 psig
A pipe which is 20 meter [787.4 inches] diameter and with 1 cm [0.3937 inches]
with 40,000 psi strength yield aluminum withstands 40 psi
http://www.aerocomfittings.com/barlows.html
Construction of pipe:
Circumference of 20 meter diameter pipe is 62.83 meter [206.14 feet]
Having panels 2.166 meters [7.1 feet] wide and which require 29 panels to create the circumference.
Each panel would be slightly curved so as to make the 20 meter diameter pipe.
Each side of panel will have 2 cm wide flange at right angle to panel. The 2.166 meters wide
panels include the width of both flanges. Two panels will butted together and welded to hold the
flanges together. the flanges add rigidity and offer location to weld which doesn’t affect the structural
strength of the tempered aluminum panels. The flanges also provide a structure that thing can attached
to it which are inside the pipe.
So one 29 weld on outside and 29 welds on inside of pipe
The panels would be about 12 meters long and have some kind flange allowing ends to be welded to together
and be thick enough to allow for loss of strength from the welding. And outside pipe will be smooth.
Total number panels 29 times 20 is 580 pieces. And total length of welds, 32.86 km.
And panels would manufactured and shipped to a drydock to be assembled. Also one could build in segment
of 20 diameter and 24 meter tall cylinder and one could have additional end pieces which used to more
easily connect the segment. So there would be 10 segments to mate with each other.
And since roughly the 244 meter length totals 414 ton, each segment is 1/10th of this.
Making it in such structural fashion, could allow thinner wall construction, but we continue assume
it equal to 1 cm thick, and roughly the flanges and other types of attachment points are insignificant added
mass.
How it works.
Inside the pipe at the top one has containers of liquid air and some fuel. The most amount tonnage is the
liquid air, and fuel is used to warm the air. Inside the pipe, air temperature could range from -150 C
to 100 C. And amount time spent at such extremes is seconds of time- one mostly just affecting the air
temperature- or there shortage of time for these temperature to affect the structure [or people if for
whatever reason they in there during it’s actual operation].
Or also there a top to the pipe, and it keep the air in and is the launch pad. And the bottom of pipe
is open.
Anyways there details of how one put the rocket on the pipelauncher. Obviously the rocket starts not fueled.[hard to move otherwise]
So without rocket, one has about 500 + tons of pipelauncher. And need enough air inside the pipe to push
the water about 2 meter below surface [314.159 tonnes per meter]. So the top of the pipe could be floating
10 meters above the water, with the remaining 234 meter of the pipe under water. And air inside the pipe
being about 12 meter high. And the top 5 meter of pipe have the liquid air and fuel, and burner of fuel.
Fuel could be natural gas. And have sprayer/sprinklers which spray in the liquid air. Now one could just
pour liquid air down into the water below and the heat content of the water would turn the liquid into a
gas [a gas at the temperature of the water]. So if poured say 1 ton of liquid air into the water below,
the water would be freeze, but would get cooler. And that creates about 600 to 700 cubic meters of air
at 1 atm pressure.
So since pushing water down about 2 meters the air pressure is 1 atm plus 1/5 atm, absolute pressure.
Or 2.94 psig.
And 12 meter high times 20 diameter is 3769.9 cubic meters of air. So 1 ton of liquid air only adds about
1/6th of the total amount already in there. So the pipe rises by about 2 meters.
One could see that one might need a lot of tonnage of air, but if we cool and warm the air, we need less
tonnage. And btw, since LOX can be about 5 cent per kg, we can assume we could get liquid air also for about
5 cent per kg, or $50 per ton.
So pour 5 tons, and it rises 10 meter, and then heat the air to 100 C with burner.
So say air was 20 C [293 K] and warm to 100 C [373 K] and increase the air temperature by about 25%.
If we had doubled the temperature the 22 meters of air would increase to 44 meter, with 1/4 of that
it increase by about 5 meter. So 100 c and 27 meter of air. And outside pipe is 25 meter above the water.
Now, we spray the hot air with liquid air and lower air temperature to -150 C [123]. So half of 100 C [373 K]
is 186 K. So drops by a bit more than 1/2. Or down to around starting level of 12 meter of air.
So when one cools the air, the pipelauncher drops. And will continue past point it floated because of the
momentum from the falling. So falls and then bounces back up and rise above that level again, and falls
again, etc.
As for rocket launch one put the rocket on the pipelauncher, when it’s 5 to 10 meters above the surface.
Add air, and fuel the rocket. And add air until it’s about 50 meters above the water, spray liquid air,
and as near the surface surface, light the burners, dump liquid air, and continue spraying liquid air to add
air and keep it so doesn’t get to 100 C.
And the time going up is about 5 seconds before one stops accelerating and rocket blasts off.
Of course the question is does adding about 100 mph to rocket which will eventually go +17,000 mph is worth
the effort [and risk of doing something new?].
Well, first off, this pipelauncher should not cost a lot to make- a few million to make, a few million to test.
Which could be cheaper than buying and using land.
One need more infrastructure than I have mentioned. One needs lightening towers for thing.
One also needs deep water, and might need to go hundreds of km off shore to find it. But it could be parked
near existing launch range. Or it could put at the equator for satellites going to GEO. Or going anywhere
one gets more of earth’s spin at the equator if launching to zero inclination.
Anyways, does adding 100 mph [45 m/s] help, obviously Without the addition of rocket power it’s not going far.
But it’s going far enough to make easier for a crew abort “on the pad”. But in simple terms in time to reach max q
or about 1 minute one added 60 seconds times 45 m/s to the elevation [2700 meters]. So if by time one reaches
Max Q one is 2700 meter higher than one would be otherwise, one would have less air density and therefore
less dynamic load. Though one also keeping added to elevation in 2 and 3 minute mark, and allowing for more
rocket power in more of vacuum conditions.
One could see as making up for the loss of needing to keep enough fuel to re-use the first stage.
One also could get higher range to max payload. Said differently if you add fuel and have larger payload you
don’t accelerate in the beginning the launch very fast, and the added 45 m/s “makes up” for such losses.
One could also go the other way, say lifting smaller payload and one uses less rocket fuel, well the added
45 m/s saves on the amount of rocket fuel one use. Or it’s equal to about 10 second of rocket engines going
at full throttle.
Or falcon -9 has burn time of 180 second, and goes thru about 500 tons of rocket fuel- 2.5 tons a second.
So around 25 tons. So say 18 tons of LOX and 6 tons kerosene.
Roughly a pipelauncher could use more than 25 tons
of liquid air, but less than 1 ton of natural gas. So only $10,000 of fuel. And suppose 3 times this for the heavy. So less fuel and a bit more air- but less oxygen.
Skran was puzzled by the 6.4 metric ton GTO weight of FH. 75% of the geo sats weigh that or less. Elon is clearly going to multimanifest, and the price listed is amazing. It beats Ariane 5 by a huge margin.
“With high probability, both SLS Block I and the Falcon Heavy will be flying in 2018–19. The FH seems a clear winner for customers wanting to launch less than 53 MT to LEO and 21.1 MT to GTO.”
This is something the article intentionally avoided. SLS has one customer, NASA. The FH could have NASA as one customer. Even if SLS had other customers, NASA couldn’t meet the production schedule. This article may be a stealth analysis of what NASA should do but if it is one of what is the best option for all customers, you don’t even need to do an analysis.
–This article may be a stealth analysis of what NASA should do but if it is one of what is the best option for all customers, you don’t even need to do an analysis.–
And what happens if SLS doesn’t actually lift 70 tons to LEO?
[I won’t be first time “they” were overly optimistic- or things tend
to be added which increase the dry mass, etc]
This article kills the white elephant. If voters paid attention it would not have lasted this long.