Pure Oxygen injection as opposed to Nitrous Oxide?

[dieselgeek]

I am being asked to "attempt" to tune a custom controller some guys built for Oxygen Injection as an alternative to Nitrous Oxide.

The only thing I could find worth reading was the claim that the Germans tried this in WW2 and found Nitrous Oxide to be a lot easier to use/tune/etc without blowing up the engine.

Anyone else know of any other guys who have tried this?

[Bamfster]

There was a guy here but he passed a few months ago. Just a layman's thought .... isn't straight O2 way to flammable/volatile? IIRC, that's why the Germans added the oxides of nitrogen .... to tame it down.

[Bob Holmes]

That's also my recollection.

Scott, if you take this job, make sure there is a big thick wall between you and the engine.

[dieselgeek]

This is not a backwoods effort. These guys built themselves a serious electronic control system, they've performed a load of engineering, and have simulations that show it can work.

The engine is a carbureted BB chevy. Company has a complete development dyno cell, etc. But they have a good sense of humor, they believe there will be some carnage before the concept is proven.

If I am allowed I'll let you know how it turns out.

[milner351]

yea - safety is a big deal. We're not talking super compressed liquid oxygen rocket fuel type stuff here are we? That stuff is stupid dangerous. I've seen pictures of liquid fuel rocket test stands twisted into pretzels when that stuff got out of control.

[dieselgeek]

I'm looking at the design paperwork for the controller, based on the nozzles they are using, and the fact that they're closely relating O2 *temperature* as well as pressure, I have to assume this is a liquid oxygen system. It's got all the same requirements of a liquid propane injection system and a set of *extremely* high pressure capability injectors - I'm pretty sure they're injecting liquid.

[BKBridges]

DG,
I think Ive posted the pic below before of my first rocket experience... Jet A and LOX. Note the parts blowing across the desert floor. I designed and machined the injector plate and lox dome (destroyed in the explosion). Those are the two round parts you see in the air. The big problem with pure oxygen and fuel is the unpredictable nature of the UN-burned LOX and Fuel. When the two come together without the correct heat input, they get real nasty. Mixed together nicely and lit off correctly, they make a lot of power (1000lbs thrust in this case.) The next rocket we made clogged the injector plate on the rail and fell over. We couldnt get near it for the whole day as we waited for the LOX to "go away" According to the Edwards AFB guys just stomping on the ground could make the mixture go off violently...Im assuming the heads are going to be coming off the BBC at least a few times in unpredicatable fashion. Bring more than a fire extinguisher with you.

[TC]

Just remember because it looks like it's going to work on paper, doesn't mean it's going to work in real life........

Be careful my friend.........

[JeffMcKC]

Scott its been done, Garlits has the old dragster in his museum

[dieselgeek]

Scott its been done, Garlits has the old dragster in his museum

which is exactly why we're continuing forward. NO worries, I won't be close to it when we fire it, but I have a lot of confidence in the injection system and controller. The guy who designed it is a badass. Same guy who built the custom wet-flow bench that AED carbs are calibrated on. This is "government level" engineering, not homebrew.

They simply want a "gearhead" familiar with tuning nitrous and EFI to be present for the first test, which is a 10% enrichment by mass.

I wouldn't turn this down for anything!

[65longroof]

Just make sure everything is Oxygen clean, ie: no oils, grease. (Doesn't matter if it's liquid or gas phase.) Not sure that's possible with an engine... BE CAREFUL!! Suggest that they have a way to remotely shut off the supply of O2 if things go awry.

[BKBridges]

Seriously...
Fuel = anything other than a few different materials at any O2 concentration over 24%. Pressurize it and things just get worse. Plastics are no bueno at over 25psi and 24% other than KelF and a few others. Aluminum is dicey. Brass and nickle (alloy specific)are OK and wont burn. Cast Iron is OK but weak when things detonate and it entraps hydrocarbons wildly. Setting off the mixture can be as easy as closing an intake valve with no spark. Calculating the impact energy of valves, regulators, etc. is critical to determining the safety of the system at the given working pressures and concentrations. And of course, cleanliness is everything. If we were lucky enough to get to recycle a motor (Atlas vernier thrusters), our success rate recycling was about 50% due to entrapped Jet A residue that we missed. Blows em up good. External combustion (rocket) is IMO safer than trying internal combustion with LOX. Once the rocket motor blows, its all at atmospheric pressure. Not so with the BBC I fear. Id start with low concentration gaseous O2 enrichment for budgetary reasons

[Ron Ward]

[dieselgeek]

Seriously...
Fuel = anything other than a few different materials at any O2 concentration over 24%. Pressurize it and things just get worse. Plastics are no bueno at over 25psi and 24% other than KelF and a few others. Aluminum is dicey. Brass and nickle (alloy specific)are OK and wont burn. Cast Iron is OK but weak when things detonate and it entraps hydrocarbons wildly. Setting off the mixture can be as easy as closing an intake valve with no spark. Calculating the impact energy of valves, regulators, etc. is critical to determining the safety of the system at the given working pressures and concentrations. And of course, cleanliness is everything. If we were lucky enough to get to recycle a motor (Atlas vernier thrusters), our success rate recycling was about 50% due to entrapped Jet A residue that we missed. Blows em up good. External combustion (rocket) is IMO safer than trying internal combustion with LOX. Once the rocket motor blows, its all at atmospheric pressure. Not so with the BBC I fear. Id start with low concentration gaseous O2 enrichment for budgetary reasons

Well, the guy who designed the controls for this system just finished a project designing Lasers for the Navy that shoot down aircraft and satellites - a side project was the use of these "adjustable wavelength and focal point" lasers in the medical field, these are new tools that can zap a deep tumor without requiring an incision (stuff that just hit the marketplace).

The last project I observed these guys doing was a compact common rail diesel engine control system for unmanned helicopter engines... government work, again.

This project is civilian, but without giving away too many secrets - I'm perfectly comfortable standing (at a distance) and giving tuning advice on any project these guys manage to put together. I'm sure they appreciate any advice (as do I) but realize they've actually done a *little* bit of thinking ahead.

White paper for the control system shows multiple failsafe controls. The planned initial hit is a 10% enrichment by mass, which is a very small "shot" - it seems to me, the containment and required special handling are far and away the bigger concerns than the actual combustion. It's pretty easy to do the math to know how much extra fuel to add with the LOX - that is the easy part.

Still, I know they're planning on a little "boom boom" so, no big deal right?

[Barry Donovan]

I remember lox in the military.

a drop of oil demonstration to scare us newb crew chiefs.

formula 1 today plays with 87 octane variants and hits 18000 rpm.

the big dumb big block does not need a bomb.

if lacking air is seeming to be the problem...play with simple boost.

being as educated as the crew is to put this together...target the carb or something.