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One of the main challenges with using a pintle injector for a nitrous-ethanol ipa combo is spray angle. A lower spray angle is desirable because it means the mixed propellant has to travel further to reach the wall, and so can disperse more. However, when using nitrous-ethanol ipa as propellants, a high mixture ratio is often used. This means that the nitrous will have a lot more momentum than the ethanolipa, and since the pintle is ox-centered (there is basically no way to manifold the regen cooling to the center of the injector to have it be fuel centered) the spray angle will be exceedingly high. However, we intend on drilling the pintle holes at an angle to enforce a lower spray angle.
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