Interesting subject. Jet A-1 costs ~$3/gallon worldwide. RP-1 rocket fuel costs $93.87/gallon at DoD prices (I didn't expect it to be so expensive, but it is a special grade and is not produced at the same scale as jet fuel, Diesel fuel, or gasoline). Liquid oxygen is available industrially at $0.13/cubic meter, or $0.09/metric ton, or $0.0005/gallon (that's 5/100 of one cent per gallon...bottled water costs orders of magnitude more). Here's the sauce. https://www.intratec.us/chemical-markets/oxygen-price
A rocket liquid oxygen tank is just a steel or aluminum fuselage, no insulation. The liquid is allowed to boil off after filling. Typically, a layer of frost will surround the tank exterior (see this on photos of the X-15 carried aloft).
Bottom line is that rocket propellant cost is not a problem. The rest of the rocket is the expensive part, and air launch allows the whole expendable package to be smaller for the payload delivered to orbit.
I will relent. I did my search on "liquid oxygen" but I now see that the source material is ambiguous---and I am running into dead ends trying to find alternative price data. So, if we construe the source data as gaseous oxygen, that would involve a proportionality factor of about 1000, leading to a price point nearer $0.50/gallon or $90/tonne. It gets more expensive in smaller quantities, so if you are not used to tonnes of the stuff, our numbers may be compatible. The point being, it is not very expensive for rocket propellant. (I am also relying on what I remember from DoD pricing specifications from the 1960s, in which it was nearly at the point of water.)
Jet engines are nice, but they can't get into space, so what is your point? That it is better to use an airplane to get part of the way there? Welcome to air launch. (I once worked for a design supervisor that was enamored of air launch, to the point of designing configurations to be launched from the topside of a 747. Some of these launch vehicles were as big as a 767 fuselage! The basic idea goes back to a science fiction story by Otto Willi Gail in 1928.)
Interesting subject. Jet A-1 costs ~$3/gallon worldwide. RP-1 rocket fuel costs $93.87/gallon at DoD prices (I didn't expect it to be so expensive, but it is a special grade and is not produced at the same scale as jet fuel, Diesel fuel, or gasoline). Liquid oxygen is available industrially at $0.13/cubic meter, or $0.09/metric ton, or $0.0005/gallon (that's 5/100 of one cent per gallon...bottled water costs orders of magnitude more). Here's the sauce. https://www.intratec.us/chemical-markets/oxygen-price
A rocket liquid oxygen tank is just a steel or aluminum fuselage, no insulation. The liquid is allowed to boil off after filling. Typically, a layer of frost will surround the tank exterior (see this on photos of the X-15 carried aloft).
Bottom line is that rocket propellant cost is not a problem. The rest of the rocket is the expensive part, and air launch allows the whole expendable package to be smaller for the payload delivered to orbit.
Liquid Oxygen ---- as a liquid --- will be in the ballpark of $1-$2/pound
A jet engine gets it for free from the air.
I will relent. I did my search on "liquid oxygen" but I now see that the source material is ambiguous---and I am running into dead ends trying to find alternative price data. So, if we construe the source data as gaseous oxygen, that would involve a proportionality factor of about 1000, leading to a price point nearer $0.50/gallon or $90/tonne. It gets more expensive in smaller quantities, so if you are not used to tonnes of the stuff, our numbers may be compatible. The point being, it is not very expensive for rocket propellant. (I am also relying on what I remember from DoD pricing specifications from the 1960s, in which it was nearly at the point of water.)
Jet engines are nice, but they can't get into space, so what is your point? That it is better to use an airplane to get part of the way there? Welcome to air launch. (I once worked for a design supervisor that was enamored of air launch, to the point of designing configurations to be launched from the topside of a 747. Some of these launch vehicles were as big as a 767 fuselage! The basic idea goes back to a science fiction story by Otto Willi Gail in 1928.)