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72MJ escape velocity, storage for 5 hours on mains

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Andy

Sat Feb 14 2015, 03:10AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Hi im just think about what would be needed to store 72MJ of energy and release it over a ten meter barrel.

At one hour at 240 volt would be 84 amp , is there any way to release that energy for a 1 kg payload.

Justin

Sat Feb 14 2015, 04:43AM

Registered Member #46164 Joined: Wed May 07 2014, 08:16AM
Location: California, USA
Posts: 89

Oh about a warehouse full of super capacitors.

Sulaiman

Sat Feb 14 2015, 05:15AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

you could electrolyse water,
less than 1 litre of water electrolysed to hydrogen and oxygen,
remote operation may be a good idea

P.S. a compressed hydrogen & oxygen stoichiometric mixture will self-detonate.

OR

14,400 photo-flash capacitors from disposable cameras?
(e.g. 100 uF @ 316V each)

klugesmith

Sat Feb 14 2015, 05:23AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1714

It would be quite ordinary technology if you put the 1 kg payload on a 735-metric-ton space elevator platform.

Raising the platform 10 meters in 1 hour would store 72 megajoules at a rate of 20 kilowatts.
You could do it with a 27 horsepower motor, plus allowance for losses in gear train or hydraulic pump.

The Subject line in OP does not match the message body,
so it's not really clear what Andy wants to do.

Andy

Sat Feb 14 2015, 05:27AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Water converted to gas, would only need to increase to 7.5 atm, instantly to supply 12km/sec velocity to reach escape velocity .

I was wondering of ways to convert 72MJ into KE to fire something into space.

It doesnt have to invole caps or inductors.

Just brain storming.

Sulaiman
With h and o to stop detention, would have a steel struct inside the chamberto break the shockwave and lower the damaging energy wave.

Kuldsmith
The life long goal is a space eelevator, but you have to start at the bottom :)

Halfdead
Just basing it on money isnt a problem at this stage, but year that will put a halt to it.

Patrick

Sat Feb 14 2015, 10:12AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Im not sure if he means the goal is to push 1kg up to orbit, but "escape velocity" in the title suggests so.
theres this that basically is a solution to the energy supply-coupling-generation problem :

but its not electromagnetic...

it explosively (like RDX) fires a slug down a 90 degree barrel to compress H and O to detonation as previously said (by sulaiman), the the barrel fires at some angle upward.

klugesmith

Sat Feb 14 2015, 05:13PM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1714

Good link, Patrick, but read it more closely. That Livermore gun, and other 2-stage hypervelocity guns, use pure hydrogen between the piston and the projectile. The high-pressure, high-temperature transfer fluid needs to be (relatively) low density, thus have a high speed of sound.

The Internet shows that the SHARP gun demonstrated velocities of 3 km/s. I saw smaller ones at Caltech Geological & Planetary Science lab.

A contemporary NASA design gets 1 inch pellets up to 7.5 km/s.

Gerry Bull's vertical HARP gun reached about 2 km/s and launched things into space (i.e. much higher than 100 km).

Conventional Explosively Formed Penetrators can hit around 2 km/s without any gun baggage. I wonder how much HE it takes to release 72 MJ?

Andy, why did you choose a 10 meter acceleration length? Your 1 kg projectile needs to withstand 735 metric tons of force, for acceleration of 735,000 gees. What will it be made of, and what good will it do?

Patrick

Sat Feb 14 2015, 08:07PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

klugesmith wrote ...

I wonder how much HE it takes to release 72 MJ?

thats a good question, thats basically a reasonable volume of propellent or HE for an artillery shell.

YEP, wiki says...

Energy content
See also: TNT equivalent
Cross-sectional view of Oerlikon 20 mm cannon shells (dating from circa 1945) showing color codes for TNT and pentolite fillings

Pentolite is a high explosive used for military and civilian purposes e.g. warheads and booster charges. TNT is reported to contain 2.8 mega joules per kilogram explosive energy.[16] The actual heat of combustion is 14.5 megajoules per kilogram, which requires that some of the carbon in TNT react with atmospheric oxygen, which does not occur in the initial event.[16] The explosive energy utilized by NIST is 4184 J/g (4.184 MJ/kg).[17] The energy density of TNT is used as a reference-point for many other types of explosives, including nuclear weapons, the energy content of which is measured in kilotons (~4.184 terajoules) or megatons (~4.184 peta joules) of TNT equivalent.

For comparison, gunpowder contains 3 megajoules per kilogram, dynamite contains 7.5 megajoules per kilogram, and gasoline contains 47.2 megajoules per kilogram (though gasoline requires an oxidant, so an optimized gasoline and O2 mixture contains 10.4 megajoules per kilogram).

Chemical energy is just all-around easier to assemble and keep than electrical, we keep having this problem as humans. (drones in my case) nothing really allows rapid reliable conversion. Even fuel cells to capacitors would be a difficult scheme to muddle with.

BigBad

Sun Feb 15 2015, 10:22PM

Registered Member #2529 Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 600

Tesla model S seems pretty good at storing energy though.

Dunno what the momentary power of a model S battery would be.

klugesmith

Mon Feb 16 2015, 04:48AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1714

The dual-engine Model S P85D claims 691 horsepower (515 kW). Much less than twice the single-engine rating, so maybe we are seeing a battery power limit. The car is faster than a Dodge Viper SRT10, but too heavy to beat a Lamborghini LP570-4 Super Trofeo Stradale.

Compared to the 306 MJ battery capacity, that power level is what RC modelers would call a 6C discharge rate.

Andy needs his 72 MJ in less than 2 milliseconds, in fact a "2 million C" discharge rate.
Too fast for chemical batteries or ultracapacitors, but ordinary for HV pulse capacitors as at NIF.

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