Wingtip to Runway light protector Concepts

Steve, the wing's full of water, so mix some of that in with the O2 and you'll have a more massive jet.

-Tom

On Saturday, January 7, 2017 at 10:55:39 AM UTC-8, Steve Koerner wrote:
https://en.wikipedia.org/wiki/Cold_gas_thruster

run the numbers on specific impulse.

best,
Evan

Damn. I knew somebody would do that to me. OK then, here goes some crude top level physics...

I'll start with my own guesstimation that 15 lbf near the wingtip for 3 seconds will be enough to get over the runway light. That's an impulse requirement of 45 lb * sec.

I don't know anything about designing nozzles but for the sake of argument, I will send my gas out at 89% of the speed of sound = 1000 ft/sec.

Impulse relates to change of momentum as J = delta m * v. Solving for the mass of gas flow required: m = J/v = 45/1000 = .045 slug.

The density of plain air at seal level is .00238 slug/cu ft. But sense we're using oxygen instead of air, we get a bit more density, like .0027. So to relate the required mass to the sizing of oxygen bottles as we are normally familiar with: .045 slug / (.0027 slug/cu ft) = 16.7 cu ft. Doable! You saved your wing for the cost of an oxygen refill.

That's right, Tom. I was thinking of that on my way back from the airport just now. I logged into RAS to say what you said.

If we incorporated a little ballast water to the mix we can operate at lower pressure which would be good for a number of reasons and also consume much less gas. Maybe a large CO2 cartridge in the wing would do the trick. In which case the system wouldn't necessitate a pressure connection across the wing root, which would also be a good thing.