Some old ideas that might help to go to space.

In addition to those mensioned by x-prize competitors, here are a few other methods.

1. Using the slope of one of the higher mountains near the equator (like the Chimborazo 6310 m / 20,703 ft) to install a maglev rail. Near the equator, the earth rotation gives a maximum extra impulse to the rocket.
Combined with the acceleration of a maglev, that would make an alternative for launching it from an airplane. The spacecraft could leave the maglev close to mach 1 (to avoid large avalanches caused by sonic booms) when the rocket engine takes over.

2. Sea launch uses a floating platform near the equator. But they could have done more. Suppose they would mount their rocket on top of a huge cylinder, lighter than water. When the cylinder is pulled down and then released seconds before ignition, it would give an additional acceleration to the rocket

3. There is a strikingly simple way to increase the available energy in rocket fuel without adding (much) weight and to be ensured of ignition in a highly simplified rocket engine: Polarize the stuff ! Take electrons away from the oxidizer and add it to the fuel. The only extra weight it will take is for extra insulation, but that may be entirely compensated by the saved weight in the engine . When the fuel & oxidizer valves are opened (that’s all there is to do) the electric discharge ensures ignition and the simple valves with some built-in flow regulation do the rest.

Okay, you got my attention with #3. I wanna hear more about how this would work.

It is like charging a (huge) condensator and discharging it via a spark in the combustion chamber of the engine. The spark also ignites the fuel/oxidizer mixture when both are "released" to the engine.

I never did a test of this, only calculations.

So basically you're making a huge wet-cell battery... Are you positive you'd be able to make it spark hot enough to ensure ignition? What are the equations?

That’s not such a good idea. The electrons will arc uncontrolled to the opposite side as soon as the two chemicals touch. This will ether do nothing, blow up the motor or cut threw the back of the motor and follow the pipes up to the tanks. Where the discharge would supper heat the tanks contents to the rupture point. Ever the insulation would be cut by the electoral arc. On a good note you would win the speed to orbit X-cup. But repeating it would be out of the question.

But your idea dose have some merit. Try using an arc welder. This would give you a far better way of controlling the arc. I don’t know if this will give you some extra power but it should make a continuous ignition.

You would get that if you use good electric conductors for all those electrons.
In the described case, the electrons are controlled because fuel and oxidant are relatively poor conductors flowing to the combustion chamber via pipes. Most electrons travel only because of this flow of fluids. It is the task of the valves regulating the flow to ensure that sparks are kept out of the reservoirs.
Please read also the next reaction.

A wet cell battery ??? NO ! NOT AT ALL ! ! ! ! In a battery (or accumulator) an anode and a cathode are chemically interacting in a different way with the same electrolyte to ensure the fixed voltage until chemical saturation. In some cases this process can be reversed (accumulator) by applying a controlled reverse current and using an higher voltage that the nominal voltage of a battery.

You asked for it, so here is some tech talk (and I try to make it understandable for everyone)
In the proposed case, there are 2 reservoirs electrically insulated. This is really a capacitor (or condensator, whatever you want to call it).
For each Coulomb (which is the unit of charge; -1.60219 x 10^-19 Coulombs/electron) transferred from one reservoir to the other, the voltage difference between both reservoirs will increase by one volt if the capacitance of this capacitor is exactly one Farad. (The exact capacitance can only be calculated if the shape and the proximity of the reservoirs is known).
V = QF Volt ; Q = charge in Coulombs ; F = Capacitance in Farad
Anyway, given enough electrons (a huge reservoir is no problem) and a sufficient insulator, you could charge up this system to whatever needed voltage. Expect something like 60000 volts needed to guarantee a spark, since even at ignition the pressure inside the combustion chamber is well above 1 kPa (=kilo Pascal. Sorry, I only think in metric-KMSA units : 1 Pascal = a force of 1 Newton per square meter. 1 atm = 101,325 Pascals = 760 mm Hg = 760 Torr = 14.7 psi).
There are some formula’s to calculate the minimum voltage, but they use tables with specific values for specific dielectric materials in a static case. But here we got a mixture fuel+oxidizer+exhaust gas because fuel and oxidizer are constantly in reaction, so a dynamic system. But lets keep things simple The capacitor can be charged to whatever voltage needed and those mentioned 60000 Volts are comparable to what a park plug delivers in a typical car engine to ignite also fuel+air under pressure.

A secondary effect of this "electrically charged" fuel system could be that it gives more specific thrust right after ignition but normalizing as the fuel (and charge) is consumed. (and here I was not so sure about my calculations, and that’s why so far I did not mention it.) Only one spark will not have discharged the "capacitor" since the whole system also limits the current (the fuel and the oxidizer are the conductors of the electric current but electrically they are also resistors) It is even likely that there will be a number of sparks during the first seconds. Anyway, even without sparks, consuming the remaining electric charge should result in a more violent combustion (gradually normalizing), which (normally) means an higher temperature inside the combustion chamber and consequently an higher pressure and more specific thrust. Maybe I need to do some research and set up an experiment to see what really happens.
It is the shape of the nozzle and pure physics laws that turns hot, high pressure low velocity exhaust gasses into lower temperature, lower pressure but high velocity gasses leaving the nozzle. The mathematics (and needed insight in chemical reactions & thermodynamics) to calculate such a specific thrust isn’t easy either. Furthermore, for me it is more than 25 years ago that I learned how to use Navier-Stokes equations and a few things got rusty meanwhile. Besides, NS-equations are only valid for the non-turbulent flow, so mere approximations, and that is why even NASA does some "trial and error".

Note that a few other tricks could be done with the ionised fuel/oxidizer. Electromagnetic acceleration of jets inside the combustion chamber or even of the entire exhaust jet. A combination of an ion-engine (but fading) and a cryogenic engine ! Some ideas to work out !

Sounds like a cool idea. It would be great if it works out. Assuming it works, how much weight could it shave off?

Thanks for the clarification. (Believe it or not, I actually caught most of it... I guess Chem I finally came in handy for something.) If nothing else, it's worth experimenting with. I'll have to keep that in mind if I decide to go crazy and specialize in propulsion rather than structures.

As stated above, the gain in weight depends on the extra insulation.
However there should be anyway some other benefits.
- The electric energy that was put in, somehow should come out, and logically that means higher thrust.
- As simpler engine construction means cheaper (no ignition system, electrically controlled valves replacing the turbopumps, some of the cooling system also becomes obsolete, etc. )

Note that there are propellant combinations that don't need an ingition system. They are called hypergolic fuels. Hypergolic stuff just start burning whenever contact between compunds is made. Fluorine for instance is hypergolic with several other fuels and gives an high energy. But fluorine is highy toxic and that is why only the Russians still use it in some cases (RD 107 engine ?). Most "acceptable" liquid propellant combinations need an ignition system.

True, but remember that you're using a helluva lot of that electric potential up in the "ignition" system (sparks waste energy like a Hummer sucks gas), so your thrust gain won't be too great. There should still be some gain, though.

I think you;d achieve better results if you polarize the exhaust gases(maybe with electic discharges) and the accelerate them further with an electric field.
It'd be kinda like mounting an ion thruster behind a chemical rocket engine.

Sorry I did not post sooner put I was/still passing kidney stones. What a Happy Jo Jo week this was.

For polarizing the fuel you will also have to change out most of the conductive material in the engine. Since electricity likes to use the path of least resistant. And this will ground out you polarized fuel.

There is another method you can try. Ionizing the fuel mixer just before it reaches the combustion chamber. This will require you to strip the electrons from one of the two fuels and charge the other. When the two fuels are mix together you will get a better combustion then normal. Since the molecules will be attracted and will cause the fuels to mix together better just before combustion. This should add thrust and/or fuel savings to the craft. But how much will depend on the type of fuel you use and how much is normally wasted unburned. This system will probably be the same amount of weight as if you added the insulation in you perverse idea. This will probably work best on larger crafts where the weight different is minimal and the fuel savings are greater.