Brian does Ridders flame eater

[Cuttings]

[QUOTE=brian Rupnow;1162211]I'm down to the point now where I'm making pieces so small that it should be against the law!!!
Brian, I got a good laugh from this comment.
On the subject of oil I was wondering if something like the synthetic 0-20 oil we use in some of the modern auto engines would give you very little drag.
It is kind of like coloured water.
The only draw back is it's kind of pricey stuff, but one litre would probably last a lifetime for what we are doing.

[brian Rupnow]

Today I managed a con rod. It wasn't easy and it isn't pretty. Actually this is the second attempt. The first attempt--I don't want to talk about it. The bearing was only available with shields, which made it 5 mm wide rather than the 3 mm that I expected. This lead me to making a con-rod .094" thick with a 5 mm wide (0.197") hub. I am going to attach the bearing to the con-rod with a dab of Loctite. Right now it's a slid-in fit.

[vpt]

Wouldn't ceramic bearings be a good choice if you wanted to run them dry? Or are they not a good choice for vibration (engine) applications?

[brian Rupnow]

Wouldn't ceramic bearings be a good choice if you wanted to run them dry? Or are they not a good choice for vibration (engine) applications?

I really don't know. I have no experience with ceramic bearings.

[brian Rupnow]

Yesterday afternoon I decided to buy a 12" length of cast iron to make pistons from. I do have lots of short pieces in my stock drawer that would have each been good to make one piston, but this cylinder is kind of a special case, because the internal valve and the piston must both be lapped fits. Since both the internal valve and the piston would both have to be exactly the same diameter, I decided that this was the best way to do it. My cylinder is about 2" long. I turned a length of cast iron down for a length of 2 1/2" to a point where it would just start into the cylinder but not slide in. Then I coated the machined area with 600 grit carborundum paste and very carefully with the lathe running at its lowest speed, I manually worked the cylinder onto the rotating cast iron. This is very dangerous, and you want to be prepared to immediately let go of the cylinder if it "grabs" and starts to turn with the cast iron. By letting the 2" long cylinder move to the very limit of the turned cast iron and then sliding it back and forth, this resulted in the full length of the bore being lapped to size, and guarantees that the parted off pistons from the cast iron will be lapped to the correct outer diameter.

[brian Rupnow]

Mechanically, the engine is finished. I will endeavour to build the alcohol burner this coming week, and then see how much is involved with actually getting the engine to run.

https://www.youtube.com/watch?v=yJYLv-NUWR8&feature=youtu.be

[BCRider]

Just watching your video and a couple of the others that showed up in the sidebar and I suddenly had an epiphany.... What about a little tubular inlet manifold with an electric heating coil in the tube? The vacuum with the port open would draw the heated air inside the manifold into the cylinder where it would cool off. So no flame and no carbon or condensation.

I'm thinking old hair dryer heater element wire wound around a little non burning core and running off a 12v battery or power supply. Something that will glow red or nearly red with around 3 or 4 amps into it.

Looks like I've got myself a project now. First off is to build a flame licker of my own with an "internal" valve similar to your Jan Ridder's engine.

[brian Rupnow]

BCRider--I don't think your idea would work. The flame sucked into the cylinder burns the oxygen in the cylinder and leaves a vacuum.--That vacuum is what pulls the piston up from the far end for another cycle. Heating something else and then waiting for it to cool off isn't going to create a vacuum.

[Willy]

BCRider--I don't thin k your idea would work. The flame sucked into the cylinder burns the oxygen in the cylinder and leaves a vacuum.--That vacuum is what pulls the piston up from the far end for another cycle. Heating something else and then waiting for it to cool off isn't going to create a vacuum.

Brian perhaps my perception is flawed but I thought the principle of operation of these vacuum engines was that they ingested some form of heated air that would then turn to a vacuum in the finned heat dissipating cylinder. The hot air would contract and form the vacuum to power the engine.
Would not any source of heat capable of the expansion/contraction ratio sufficient to operate the engine not work?

[J Tiers]

Brian perhaps my perception is flawed but I thought the principle of operation of these vacuum engines was that they ingested some form of heated air that would then turn to a vacuum in the finned heat dissipating cylinder. The hot air would contract and form the vacuum to power the engine.
...

Likewise. Do I not understand this? The oxygen is 20% or so, and is converted into another gas plus water. Seems that would not be a lot of change of gas volume.

I figured the hot air contracts and causes the piston to move. The flame has to as nearly as possible go into the cylinder, to have the gases as hot as possible for maximum vacuum. It may be quenched in any case by the gases being sucked through the smallish opening in a cold (relatively) cylinder, so that flame may not actually exist inside the cylinder (it could).

[brian Rupnow]

Willy--You might be mixing up the theory behind Stirling engines and flame sucker engines. In Stirling engines, the air inside the engine never exchanges with "outside" air. The heat source at one end heats up the air at that end--the air at that end expands--it is a closed system so as that hot air expands the pressure in the engine at the hot end, it puts pressure on all the air in the engine, thus driving the power piston outward to spin the flywheel. The flywheel turns and drives a "displacer" piston from the "cold" end up into the hot end area. The displacer piston has about 0.040" radial clearance all around it. the hot air in the hot end is displaced by the piston and flows down to the "cold end" where the fins are and cools off by radiating the heat away. This then creates a partial vacuum and sucks the piston back up to top dead center---however, the power piston and the displacer piston are offset by 90 degrees, so that by the time the power piston gets back up to the top, the displacer cylinder has withdrawn to the cold end and the external flame has heated the hot end up again to repeat the cycle.
------------In a flame sucker engine the external flame is sucked down into the cylinder because to start it you spin the flywhel by hand, thus making the piston head down towards bottom dead center and it sucks the flame right down into the cylinder. As the piston reaches bottom dead center, the little "trap door" at the end where the flame was sucked in closes, the flame in the cylinder is shut off from the outside atmosphere, so it consumes what oxygen is inside the cylinder (thus creating a vacuum) and goes out. The vacuum sucks the piston back up towards top dead center, and just as it goes over top dead center the trap door opens and allows the flame to sucked into the cylinder again to repeat the cycle.

[J Tiers]

Not trying to argue too much here, but where is the fuel in the cylinder to use up the oxygen? if it is sucking in a flame, the fuel would seem to be mostly used up already by the flame. That's assuming the flame itself gets sucked in through a smallish hole in the cold cylinder without being quenched out as it is whengoing through screenwire mesh. And that there is a significant negative change in net gas volume during combustion, which seems questionable... you trade an oxygen molecule for a CO2 molecule. Some of them obviously become water, so there shoud be a net decrease, but it should not be more than 10%, (two oxygen molecules become a CO2 and two H2O so half the 20% might condense out)

It's an interesting question. I'm still leaning toward the hot air idea..... got a reference on the operation?

I DID look this one up on google, and Tiffipedia suggests it is hot air that is cooled and creates a vacuum. But that reference is not always correct... depending on who has written or edited the entry.

[brian Rupnow]

Jerry--Everything I know about Stirling and flame-sucker engines has been learned in the last two months. I am not absolutely certain of my facts, but this is how I interpret things based on a lot of reading.---Brian

[sid pileski]

I agree with JT. It’s about heat differential. And atmostphic pressure pushes the piston back up the cylinder to start the cycle again.

[brian Rupnow]

I think you guys are probably right. I just did some googling trying to confirm my concept of consumed oxygen creating the vacuum and couldn't find anything to support it. Seems like perhaps it is purely heat differential.