RE: Substitute for Ether
 

The Gadget glow plug device to run a glow engine on 70 wt oil was a glow plug with a copper slug stuffed in it. It looked like a piece of 8 or 10 gauge wire with a round protruding end.

RE: Substitute for Ether
 

JMP,

Thanks for the link. Looks like about the same as we've found out here.

Kelly,

Great input, keep 'em coming. Adjusting on the fly while trying various nitro percentages and or oil content and or fuels might be a very useful experiment. It's got me thinking about something that may be at the core of the matter.

A leading question to the old hands. Can you compensate for over or under compression by adjusting the high speed mixture? If higher compression requires a needle change, in what direction and why? Same prop, same fuel.

I flew the .074 tonight on zero and 30% ether fuel with the aviation oil. Ran much better tonight than the other day. That day was warm and muggy with humidity at max. You could actually drink the air.

Today was hot, no wind, not a cloud anywhere in sight and the air was bone dry.

Re hot CP. How about one made of JB Weld with a disc glued to the bottom? Yes, the disc would have a threaded stem to engage the epoxy piston. A conventional O-ring seal would be used. The disc would get hot and transfer its heat to the thread core. This would be insulated from the rest of the head by the epoxy. As such, it would retain its heat better from full bore and at least for a while, offer a "hot plate" to the incoming fuel. Perhaps phenolic could be used?

Here's a question. Does a denser material retain heat better?

That reminds me of something stupid I did last year. I made up solid, Teflon CPs with no O-ring, just the snug fit of the oversize CP kept the seal. Worked fantastically for a few minutes. Then the engine sagged and I had to turn in the CP constantly to keep the .06 running. At the end of the run, the CP was found to have a neat, round, symmetrical hole burned cleanly into the bottom, about half way. The hole reflected the efficiency of the Norvel's by-pass port system. It was biased towards the exhaust port. That was neat to find out but the stupid part was that burning Teflon is extremely toxic,,, or so I'm told. VERY lucky that the wind was AWAY from the test bench. One whiff and who knows. [:'(]

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Hey Andy,

I got a call from Canadian Tire Customer Support today regardind my query on the Motomaster Cetane Boost. They tell me that they are expecting this product to be available in their supply first week in September and thence a week or so in the stores. Pretty much what they told you at the store in Timmins.

After reflection of my observations of my test with B20 biodiesel I tend to agree with Greg that a lot of the extra fluid and white smoke I was seeing was unburned B20 biodiesel. Obvious in light that power was down as well.

Obviously the engine was not getting hot enough for it to burn. And what of Cetane number or rating. B20 Biodiesel is often listed as having a Cetane number between 50 and 60 with plain old kerosene 5 to 10 points lower. And what does adding Cetane Boost do? Increases Cetane number?!? But it seems that Cetane number isn't all it's cracked up to be. Castor oil has a high Cetane number but doesn't burn in engines. So it seems that a high Cetane number is a good thing but if you don't have the heat to make it go pop it isn't all it's cracked up to be.

Also B20 Biodiesel has a very obvious slippery (oily feel to it). Is it enough for our little engines or is more needed and how much more?

I have been thinking more about the need for higher compression for a good idle and then being over compressed at high speed. I keep stumbling notes on F2C team racing and their use of Tetra Ethyl lead or Ferrocene as an additive to allow them to run a bit higher compression to get a bit more power out of their engines. I don't think we should be playing around with Tetra Ethyl Lead (nasty stuff and a controlled substance) or Ferrocene. The descriptions I read is that these additives delay combustion but don't effect the fuels self ignition properties. There are numerous "octane boosters" on the market. I had a quick look at the msds's that I could find and they all seem similar but different brands have different ingredients. It seems counter intuitive to use one of these in our fuel but perhaps we get the same effect as the F2C guys by adding a small % to our mixes which would allow us to run a higher compression (to enhance the idle) and run an higher speed with the same higher compression setting (hopefully there would be a compromise compression setting that would benefit both high and low end). Might even have the effect of making the compression setting less critical over all.

Andy, know anyone who does piston and cylinder chroming. I have another old PAW with a worn cylinder/piston. One option is to just get a new set but I would also like to explore the possibility of having some chrome work done; something else new to try.

Further test with the Biodiesel later this week.

cheers, Graham

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Sorry if I'm suggesting something that's already old news, but if what you need to run the diesels is heat, then... why don't you just use a glow plug or two just to get it started? Run 2.4 volts through it instead of 1.2, just let it sit for a minute, start the motor, let the motor get hot, adjust the dohickeys to make it run good, take off the glow, and fly? If I had the ability, I'd be making a test engine at this moment.

Update: saw the video any made... ok, nevermind. Unless, what you need is simply more heat than a standard glow plug can provide?

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Yes, and you may be on the right track. The idea of a glow plug to pre-heat the head/and or the fuel mixture to start did not work out. However, the idea is not dead yet. I know that applying a clip to the head of a diesel engine to start it is sacrilege but we're really only doing this for fun and the search for the why, wherefore and how to. So when we're told that commercial diesels of the truck/Caterpillar variety use a glow plug, we, as modellers, not knowing any better, imagine what WE know to be a glow plug. Not so my little chickadee, them glow plugs look nothing like we're used to.

Courtesy of Kelly, go here to get updated.

http://www.indiamart.com/glowplugs/

Notice at the top of the page that these glow plugs are NOT a wimpy little filament. It's a phallic looking stud that bloody well glows in a big way.

So, if we devised such a plug but one that was flat,,, as in a contra-piston that glows, (or just gets real hot) well, it might just work. And, that device also might act as a hot spot, in some manner, after the engine is running. Getting too complicated when just a bit of ether would do wonders? Absolutely but that would be far too easy. Done that, been there,,, no fun in that, is there?

Anyway, the latest attempt is pictured below. Made of brass, and with an O-ring installed, the piece has been potted with JB Weld and that has been inserted into the CP carrier as a mold. Yes, I'm using PVA as a mold release. So we'll have a CP that's insulated from the carrier with just a thin edge in contact. The threaded stud portion will be milled off and an insulating, phenolic disc will be glued to the top. Insulated in this manner, it may be just enough of a heat reservoir to do the trick. No glow, no amps, no muss'nfuss.


Graham,

That castor has a cetane number, implies that they got that figure by actually burning the castor in a test engine designed to do that. However, I understand that they also determine cetane numbers using math and computers or some such nonsense. Not necessarily that castor burns, just that it theoretically would burn if you atomized it fine enough and applied the right heat and pressure. Presumably, our engines don't atomize the fuel as finely as a fuel injector does.

Our LCT told me the Moto-Master cetane booster would be in tomorrow. Will get back to you on that. I also have some Cool Power oil on order. Kelly says that with just methanol and Cool Power oil, no nitro, he gets nearly the same performance as with, you just have to up the compression. After all, they do that in Europe. Now, I've tried a methanol and Klotz castor blend in the Norvel .074 and results were mixed. However, my experience with Cool Power fuel is that it not only gives you a very good top end, but the idle and transition are improved. I've tested a variety of fuels on the same afternoon, same engine, same prop, and consistently, Cool Power had the edge in the throttling department. One brand of fuel labelled as 1/2A was just terrible. No doubt it was formulated with no regard to throttling.

So, it just might be that Cool Power oil has the magic we need to make some of this stuff work better for us. Say you use only 10% CP oil with 88% kero and 2% booster. And say you still got good throttling and a good idle. Got some on order, will be interesting to try. Once again, this potentially useful suggestion comes from Kelly.

My question about compression and mixture was on the same tack as you are on in your post. Latest tests with the Norvel .15 on glow shows that higher compression requires a richer mixture. Lower compression requires a leaner mixture. Why? Don't know but if we have to up the compression to get a good idle, it may simply mean that we need a much leaner mixture, at idle, than our throttle can deliver. This was displayed to me when I would put the nose of the plane up, at idle. The burrp, burbble, fart would go away and transform into a smooth purr. Till the wing stalled, of course.

I have a spare, MP Jets throttle that I'm going to try to adapt to the .074. This throttle is an amazingly sophisticated, two needle unit and was used on their diesel and glow .06. I'll bore out the barrel to match the one in the stock, Norvel throttle. With an actual needle to control the mixture at idle, we might just wake the beast up.

About chroming, the only one I know that does/has done it is Carl Risteen in the Maritimes. I've lost touch with him, don't know how to find him again, sorry. You might consider electroless plating. You get a liquid that you bring to near a boil and just suspend your part in this for an hour or so. Chrome plating does so thicker at the edges and so, some final finishing/honing is required. Electroless gives you an even coating all round. Do a search for Caswell Plating.

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It doesn't per se require different mixture settings. Theoretically you could run at stoich fuel air ratios all the time. That is, you could put just enough fuel into the engine to burn all of the oxygen. But this isn't the best F/A ratio for power. A gasoline auto engine typically runs 14.7-16:1(stoich to lean respectively) during cruise. At WOT instead of the stoich to lean value F/A ratio is dropped to 12:1. This prevents detonation and allows advanced timing to make the most power. Could the engine be operated at stoich ratios at WOT? Yes. Compression ratios would likley have to be lower, timing retarded, and the engine would make quite a bit less power, and overall efficiency would be reduced. Aviation engines are similar in that you have a rich mixture setting for full throttle take off power and a lean cruise setting. The biggest difference is that at the rich setting octane rating of gasoline is ~20% higher.

A glow engine operates the same way. It doesn't really need any different mixture, just what we are asking it to do does. If you put a colder plug in it would change the needs again. If you ran the same engine on spark ignition I think you would see a substanitally different story. We could then separate the ignition timing from the FA ratios. Diesel injection does the same for full size diesels. Methanol has octane rating of 100-120 and glow engines run at 7-8:1 CR. This means that they are not experiencing detonation in most cases but preignition is common. It would be interesting to put a lambda sensor on a glow engine if the oil wouldn't trash the sensor. Our engines are complicated in that simplicity has tied many operating aspects together limiting flexibility. Since running rich is an effective way to control igniton timing in a glow engine, and efficiency and emmisions is the last thing we think about, it's acceptable.

I observed that my FS engines are very tolerant of idle mixture. They smooth out when lean, but they also tolerate a sloppy wet setting well. They don't transition the way I like rich. A lean idle mixture will result in misses during transition, though it idles nicely.

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Greg,

Well, it DOES require different mixture settings if you want maximum power with efficient fuel consumption. For years I had been reading highly respected engine folks who would suggest that you set your main needle a bit rich to prevent going lean in the air and burning out your engine. I could never understand that logic. If your engine goes lean in the air, you have an issue that needs to be dealt with, not a band-aid solution like running the engine rich. I always wondered, what's wrong with a perfect needle setting, not rich, not lean, exactly what the engine needs for best power and efficiency? If you set, or allow your main needle to be rich, then you get throttling issues. Why NOT best top end, efficient fuel consumption along with perfect throttling? It CAN be done with enough effort and understanding as to how it can be achieved.

I agree with you that our little two strokes are mechanically simple, but by default, they become dynamically very complex. For instance. When throttling at the intake, with a perfect high end setting, the idle goes rich. That must be compensated for by having a means to adjust the mixture at idle. If you have no means to adjust the mixture at idle you can do something mechanical to allow for a leaner run at idle. Decreasing the compression forces you to lean out the main needle to get the best power. That in turn, leans out the idle and you now have an engine that will idle and deliver good transition. The problem with that solution is that if you make a change, as in more/less nitro, different brand glowplug or heat range, or even a very humid day as opposed to a dry day, you now have upset your balance of mixture demand. Now you have to take the head off and add/delete shims to compensate. The real solution is to find the compression ratio that puts the required mixes within a range that your particular throttle can handle.

Interestingly, when you have an exhaust throttle, your idle goes lean. This is why an exhaust baffle, along with the intake throttle, works so well. The one effect compensates for the other. And when mufflers came along, baffles had to be done away with but in many case, the engine throttled just fine. The reasoning was that the muffler "kept the heat in" keeping the glow plug lit etc, etc. I've run a good variety of engines with and without mufflers and am convinced that this is not the case. It all boils down to giving the engine exactly the right mixture at all throttle settings.

As is the case with the .06 Big Mig vs the AME Norvels, the former throttles much better. This is entirely due to the 5 bypass port design. That points to the fact that engine design, as in efficient fuel flow, has as much to do with good throttling as does a good throttle. Many times I would note that to get a reliable idle, you would have to set the idle rich. That would cause poor acceleration. If you set the idle lean enough to allow good transition, the engine would eventually quit due to fuel starvation. That points to inefficient fuel transfer at lower RPMs. At full throttle, this is not a problem as the velocity of transfer is such that it overcomes the inefficiency.

In some cases, with a good design that potentially will throttle well, we can have a flame out on acceleration. Idle holds all day but the engine quits, not with a lot of smoke and spit, but with a very dry, abrupt stop. In this case, the idle is set too lean FOR ACCELERATION. Fuel transfer efficiency is very good as evidenced by the solid idle. However, when you advance the throttle quickly, the sudden rush of air overtakes the throttles capacity to deliver enough fuel, just for that moment.. This is a case where you want just enough fuel loading up in the engine, at idle, so that you have that available to you when accelerating quickly. It works exactly like the accelerator pump in you car. So you set your idle just a hair rich. Not enough to upset the idle, but just enough to allow for good acceleration. Many engines will do this, many will not, or will require complex, two needle throttles. While I WILL try the Jets throttle on the diesel .074, this, very often, is not necessary. The Norvel .15 idles and accelerates, (on glow) impeccably, but I DID have to add an adjustable airbleed. It does that less so on an all kero fuel and that is what is being worked on now.

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I've been trying to research vegitable oils as lubricants- info is hard to find, but I did find a simple explanation as to why they are superior to either mineral oils or synthetics- its due to there polar charged molecules, see the pic.
Has anyone tried the modified vegitable oil??? instead of castor?
From what info I have found it looks like "Olive oil" maybe the best after castor - I wonder how it reacts to modification.
Stewart

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I've found a sample of 100% biodiesel (B100). I'm thinking I need Amsoil cetane booster & a little ether (diesel engine starter, John Deere if I can find it). Does this sound right so far?

How about proportions? What would you use?

The engine starter is designed to be sprayed, right? Do you think I could just bubble it through the other components or would I likely loose most of it that way? I'd like to just use part of it without repackaging, if possible.

Tnx - LeeHop

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I just spray the JD into the mix. Yes you loose some. You could put it in the freezer to help reduce the loss.

My gut feeling is that it won't run. If it does run only the ether will be burning.

RE: Substitute for Ether
 

Lee,

I'm trying to get some B-100 myself. I was simply going to treat it as kerosene. Since the Norvels run on no ether and biodiesel is supposed to have higher cetane ratings, why not just try 20% oil, 78% B-100 and 2% of the cetane booster.

When mixing small batches of fuel for test, I just spray into my graduated cylinder. Spray against the side to minimize loss. From a 7 ounce can, I normally only loose a half ounce or so,, not a big deal. When I need to make up a larger batch, what I do is have an 8 ounce jar with a lid. I get a spray nozzle/tube from a can of WD 40 and use that instead of what you get with the ether spray. Insert the plastic tube into a small hole that you've punctured into the lid and just spray away.

But in retrospect, I'd first try a 40/40/20 mix, with the Amsoil at 2%. Then, if it runs, work the ether content down to zero and see how the engine behaves and handles. Make note of CP and needle settings and please let us know of your results.

MY gut feeling is that it WILL run. I was told that you absolutely MUST have ether in your fuel or your diesel engine will NEVER run. What I found out was that it'll be impossible to start by hand, but it will run, if you can get it to fire. And as we've seen, all you need is the proper use of an electric starter and an ether based prime. Throttling is still problematic with no ether but for any number of reasons, biodiesel may be a cure for that. You just never know till you try. And I'm glad to see that you're not letting dogma get in the way of experimental fun.

I spent most of yesterday afternoon running the Norvel .15 on various ether and no ether mixes. All on Aviation oil. Cetane booster was added and left out in various combinations. No matter what, the booster is a must. Yes, use it. BUT, you just never know. Do try it without.

What I found was that WITH 40% ether, 40 kero, 20 oil and the 2% Amsoil, the engine would fire off at its running setting on the CP. Backing off or turning it in was detrimental. And it ran well and idle was very good with excellent transition. This mirrors my experience with the smaller Norvels. But what advantage did we have with an all Kero fuel? Well, I got about 400 RPMs more. Plus, and amazingly, while the CP needed to be turned in for a start, once the engine got up to temps, it was turned out about 3/4 turn. And at that setting, the engine ran much more smoothly with no diesel clatter at all. WITH the ether, no setting would take away all the rattle. This is interesting and curious. My speculation. With no brass/bronze bushings in the rod, it doesn't take long for a bit of slop to develop. No harm at all in that, as it just goes so far, the extra clearance allows for lots of lube in this area and you can run like this for a very long time with satisfaction. But that slop kind of shows up as clatter with the much more diluted, high ether fuel. More kero means more of the inherent lubrication qualities of the material added to your mix. A dampening effect, if you will.

I also spent some time on the .15 as glow and experimented with compression settings. The glow, adjustable compression head suggested that the stock head was a bit undercompressed. I tested this by installing a turbo plug insert with a muchly reduced combustion chamber volume. As well, I turned down a stock button. In the enclosed picture you can see this clearly. The turbo, (on the left) and the turned down stock plug, (on the right) both gave me about a good 300 RPM more at the top end. But increasing the compression leads to a need to back out the main needle some, causing the engine to go rich at idle. So rich that the air bleed, adjusted all the way out, would not compensate. My experience with throttles said that that should not have happened so dramatically so I took the throttle apart and had a look. Here's what I found.

Most throttles that have no means to adjust the airbleed compensate for this by having the bore of the throttle body, AT THE TOP, a larger diameter than the barrel's bore. But the bore at the bottom end of the body is the same diameter as the barrel. This allows the engine to run leaner at idle and we have a compromise that gives us reasonable throttling.

This works, after a fashion, but what I did might seem counter-intuitive at first. I bored out the bottom of the body to be the same as the top end. What we had then was the bore of the body, both top and bottom, to be larger than the bore of the barrel. What does this do? It allows Bernoulli to be more effective. With better fuel draw, you have to turn in the main needle some, about back to where we were before increasing the compression. This leans out the mix at idle and in this case, to within a range that allowed the adjustable airbleed to do its work. A bonus side benefit was a distinct 2 to 3 hundred RPM boost. Why? Because a larger bore in the bottom of the body allowed the engine to breath more freely and the velocity of air across the spray bar became more effective, resulting in more power.

An interesting sidelight. Those of us that have run 1/2A know that if you hog out and tap a stock, Cox glow plug to take a standard plug, you can lose one to 1.5K worth of power. Why has been debated extensively and the consensus is that the threads of the plug interferes with combustion. Mostly because the ratio of thread to combustion volume is so much higher in a very small engine. That seems to be the case. I installed the stock plug, after testing, with an application of Loctite. Yes, I used the blue NOT the red. Anyway, the result was NOT a great increase in power. In fact, the turned down stock head, with stock plug, was nearly on par with the turbo plug, with, or without Loctite, sealing the threads.

Another interesting sidelight. We all know how dieselizing a glow engine is supposed to give us more power over glow, as much as 50% by some measures. HOWEVER, all of the tests done on the Norvel .15, glow OR diesel gave us about 10K on the same, 10 X 4 black Tornado. On diesel, the engine averages 10.25K. On glow, with 25% Cool Power, I get 10.7K with the carb and head mods. On 10% Omega fuel, I get about 10.1K. So theoretically, I should be doing, (at 50%) about 15K on diesel as opposed to the 10K with glow. Yet, they're nearly on par. HOWEVER, as my experience flying the .074 has shown, when switching back and forth and using the same prop, the diesel does have the edge over glow for lugging in the verticals. There IS another advantage to diesel and that is the much better mileage we get when running stinky power. But do we really? Could it be that if you ran the SAME prop, the difference would be negligible? That will be tested in due course.

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It was late but I really did want to find out if you get better mileage with diesel over glow. A somewhat dark video shows the glow run here,

http://www.youtube.com/profile?user=hopeso

The enclosed picture shows the engine running with the graduated cylinder used for metering exactly 1/2 ounce of fuel to the engine. No I'm not messing with you, it was dark, the tach couldn't read and the prop HAS been frozen by the flash. With this set up, there were serious issues with fuel syphoning into the engine. The runs were done with a full ounce but the engine could not take the difference in mix between a full and empty "tank". So a half ounce was run three times and the average taken and extrapolated into one ounce. Most fuel tanks are in one ounce increments and this helps you do the math more easily when comparing to your own situation.

This proves to me that diesels DO provide better mileage over glow by a major amount. In this case, it was over twice as long.

No doubt this is old news to them that know but it's just one of those things I had to see for myself.

Having confirmed this truism about diesel, I'm not so sure though, about how much more power diesel provides over glow. Many runs on this engine, diesel and glow ON THE SAME PROP, shows an average top end of 10K. Fluctuations of 2 to 3 hundred are common and reflects the ambient conditions, glow plug used, diesel fuel mix etc.

I think that diesels provide more THRUST over glow but only by virtue of the fact that they will spin a larger prop with authority. Larger props are more efficient and even at a lower RPM provide more thrust. If anything, it CAN be said that a diesel conversion WILL give you a boost but it's interesting to note where that boost comes from.

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Yesterday's run on the Norvel .15 glow/diesel was with a glow sized prop, a Grish, 8 X 4. An 8 X 6 might have been more typical but I didn't have one. In any case, glows LIKE to run fast so here it is.

http://www.youtube.com/watch?v=sn67PgV-kAw

This day we tested the Norvel .15 on glow and diesel for mileage on a Grish, 8 X 4 prop. Top end for the glow version was 14.3K and for the diesel, 14.1K, nearly the same for both.

The mileage was a different matter. On glow, on one ounce, we got 4 minutes, the same as with the 10 X 4 prop. On diesel, however, we got 5 minutes, marginally better than on glow. This was a surprise.

At least in this clip, you can see the test rig. I would initially fill it to a half ounce to minimize fuel syphoning into the engine. Then when all was adjusted and running at max, I simply squirted more fuel into the cylinder/tank and watched carefully as the fuel approached the one ounce mark and then set the stopwatch. This was a different approach from the other day and gave a more accurate measure of each run. Four runs on each fuel were done and the lot averaged out to arrive at the readings indicated.

Same RPM but radically reduced mileage. Have no idea yet why, or if it matters any. No one will fly a .15 diesel with that size prop, that's not the point.

Tonight, I installed an early .074 cylinder on my test plane/engine. This had the cylinder fins turned down considerably along with the fins on the head clamp. I tested both a no ether fuel and the 30X50X20X2 mix. The result was an engine that became real fussy and hard to dial in on the CP as well as the needle. It would not idle below 1/2 throttle. Without good throttle control, I didn't fly, but immediately re-installed the original. Both are pictured. The result was a very good flight, STRONG top end and quite good idle and transition, ON THE NO ETHER FUEL.

Switching to the ether based fuel, and re-adjusting the CP and needle, resulted in reduced top end, particularly in the verticals and a poorer idle. Not bad, but not as good as the all kero fuel.

In this case, the head button and CP were made of brass. The reasoning was that brass, having a higher density, would retain heat better and act as a heat flywheel. It SEEMED to do that although this was just one test on one afternoon. Will have to make another head button out of ALL ally and/or one with just the CP out of brass. Another good test of this notion would be to make an all brass head for the .15, so that will be done and results posted.

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Which theory says that it should make more power as a diesel? I know Davis claims that, but he doesn't list data for every engine tested, only the ones that truly benefit from diesel conversion. The second thing that would skew the results is that most glow engine will be over compressed for running large props. This results in preignition and low power output. As you found with proper compression ratio as a glow power output is similar.

There is no reason for an engine to make any more power with one fuel or another, unless it carries it's own oxygen, like nitromethane. The main reason diesels burn less fuel is because kerosene produces much more heat per pound of fuel burned.

Why wouldn't someone run a diesel at 14kRPM? If you wanted to get the HP it makes at that RPM, you have no choice. Team racers (F2C) could load up their engine to get better fuel economy but they would not be competitive because HP would be low.

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RE: Substitute for Ether
 

FWIW, someone once said :"It is the amount of air you can get through an engine per unit of time which is the real secret to high power"

RE: Substitute for Ether
 

That actually depends on the engine design and combustion method. For instance, an injected diesel(non turbo) always flows the same amount of air at idle or wide open. But a turbo diesel has the potential to make more power because it can pump more air at higher throttle. The above statment is true for any engine that doesn't use stratified charge combustion.

Andy, Combustion is a complex process especially in our engines. That's why I said what I did in post #181. Increasing the squish band in a glow engine will reduce the tendency to preignite so the benefits of increased compression and ignition timing can be realized. Using a glow plug with different characteristics also changes the combustion process. you would have to isolate the cause to make a definitve statement. To me, it's inconclusive. I would also consider trying the whole heat range of turbo plugs and a variety of squish bands. Also how are comparing compression ratio between different heads?

But what is gusto? To diesel people it's usually torque. To the rest of the world and physics it's HP. Torque is not a measure of power. If you look at drag racing 1/4 mile time calculators they use power to weight ratio. Torque to weight ratio is irrelavent. There are 6000Lb Turbo Diesel trucks that do 12 second quarters with 1300Lbft /600HP engines and gasoline 3000Lb cars that do 12 seconds quarters with 300Lbft/300HP engines. The diesel has a huge torque to weight ratio compared to gasoline but the HP/weight ratio is what determines performance.

To determine the engine performance is one thing. Throwing a prop into things really clouds it. That's why in some cases with diesels, improved prop performance can overtake reduced HP output when the engine is loaded up with a "diesel" prop, when flown in a model.

The intersting thing to do would be to get a dyno curve for both a diesel and glow version at optimized operating points. I intend to do it for a fourstroke, but adjusting the compression ratio for the glow version and doing tests will be time consuming.

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Greg,

My disadvantage is that I'm working from square one. I have no knowledge of what you speak. This allows me to apply the empirical approach, ignoring established facts. Like ether is absolutely required in MODEL diesel engines. Not so, it seems. AND with enough R&D, the throttling issues may be overcome. Some complex mechanical arrangements are being worked on in collaboration with another and we may arrive at the perfect solution in that manner. However, we have a tantalizing hint that there may be a much simpler, very much overlooked, seemingly contradictory approach. Heat, heat, heat. Maybe, maybe not.

Yes, the way I did the turbo and the turned down inserts gives us a LOT of squish band and it appears that, by luck, I got it about right. So we have a .15 running on two prop sizes up and instead of decreasing compression, value was derived out of increasing it. On top of that, I'm using 25% nitro. Who would have thunk that any of THAT would have been a good idea. Would never have happened without the adjustable compression head.

Gusto refers to the engine's response to putting the nose up and hanging on the prop. Same engine, same prop, diesel to glow, the diesel holds a hover, the glow falls out. Gusto.

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Modelers says this. Engineers don't.

RE: Substitute for Ether
 

To expand on the above comment. I did a lot of research into combustion and ignition methods for engines and engine designs. My experimental findings in my four stroke conversions have matched my research. We are not exploring new ground in combustion theory. It's new for modelers, but not new in the whole scheme of things. I posted that patent link for the carbureted compression ignition diesel a while back. That was in 1940's. It ran on oil and kerosene and had variable compression ratio. Internal combustion reciprocating engines have been studied for 150+ years.

I guess I just prefer to research to understand why things act the way they do in my experiments. That way if there is room for improvement I'll know where and why. These engines are not anything new. If you are on the bleeding edge of technology you will have few references and will have to use your expertise to figure out what is happening.

Based on my research I don't think B100 is an option for our engines the way they are now. B100 does work in injected diesels and there is reason for it. There are also limitations for B100 in injected diesels.

Now, you can only go so far with theory, so testing things is very important. My engines ran fine on the bench, but tuning for flying was different. The details of the engine design and fuel mix can only be found by experiment.

Andy, the above comment was not meant to be a stab. Looking back it may have sounded that way.

RE: Substitute for Ether
 

Greg,

Stab, schmab, not to worry, none taken, really.

I'm a modeller and I certainly may have said that ether is essential for model diesels at one time. But it was because I was TOLD that by others. And when it was explained why, it made perfect sense. But as I dabbled and experimented with fuel formulas and reduced the ether more and more, well, the darn things ran and just didn't know any better. And all along, the problem wasn't the lack of ether but poor compression velocity when starting. Kelly nailed that one, I had trouble articulating what was happening. Ether is ONLY essential to start and sometimes it isn't necessary if you can spin the engine fast enough with just a bit extra compression or alternately, a richer needle setting. And the key to it all was proper use of an electric starter.

And well, take a look at the bent rod. This happened when I was using the graduated cylinder for a fuel tank. Yes, I got distracted and didn't notice how much fuel had syphoned into the engine. On top of that, I mistakenly used my standard starter on the little .15, (at the left) when I should have used the Sullivan, Micron starter in the middle. To the right is a custom made unit from an electric power gear box and motor and a plastic pipe coupler. Topping it off is a switch from Radio Shack.

The larger unit is needed for the Norvel .40,, the middle one will start the .25 and .15 and the homemade unit is for Norvel .06s and .074s. On top of all that, I have a second socket on my box that has large, dropping resistors to reduce the voltage to 6 volts for those times when I'm not sure about the starting status of any particular engine. Start light and go up if needed. I'm afraid that that is what it takes to put on the spin, other than a vigorous flip, to get our little stinkers going,,, 'specially on no ether.

And after I applied the starter, I knew just what had happened and why, in an instant. What I didn't realize was how much fuel had accumulated in the engine. After taking it off the mount and unscrewing the backplate, I found no less than a teaspoon full of raw fuel in the crankcase. Well, no wonder. But that IS a lot of fuel and it kind of shows that you really do have to be quite careless in this area to have problems. So the old hand flip with the exhaust pointing down usually comes to the rescue.

But here's an idea for the entrepreneurs in the audience. This idea comes from my 23 year old nephew. He likes to tinker with snowmachines and dirt bikes and the like. And one day, I nearly did what I did to the little .15 in an earlier session but I caught myself. So he suggests that someone should come up with an electric starter that has a clutch as in the drill/driver types that use screwdriver bits. You know, they go snap, snap, snap when the screw bottoms out. The feature is adjustable and in the engine starter form, it could have engine sizes instead of just a numerical scale. So if one of these shows up in the hobby shops in the next six months, you heard it here first. I'd buy one,, or two.

RE: Substitute for Ether
 

Yup Andy thats bent!!!
But it is a good statement of the design and metalurgy of the Norvel Cranks :)
Stewart

RE: Substitute for Ether
 

Andy a clutch on a starter is a great idea, especially for diesels. If you could remove half or all of the planetary reduction from a cordless drill, the drill would work well as a starter.

RE: Substitute for Ether
 

The idea of the clutch starter is a good one. There is a difference in the applications, however. A screw has little mass and is a poor flywheel. A prop, on the other hand, has a significant amount of mass and won't stop the instant an obstruction in the engine is encountered. You could very well still break cranks with the clutched starter. Chances are good that the torque needed to accelerate the prop from a stop to starting speed in half a revolution would be the same as what it takes to break a rod.

I broke a crank with one of my first diesel conversions attempt with a first generation norvel .049 back in '95 or something. I wasn't even using a starter. I understand that these very early engines had poor crankshafts.

RE: Substitute for Ether
 

Likely you're right but with some massaging and modifications, one could come up with a device based on the principle that might work. I may just do that too. :D

Maybe what Skypilot suggests. Thanks, man.

And about cranks. I installed a Cox .09 crank into a Norvel .074 as my second conversion some years ago. Because of timing issues, that engine never ran well but I had no reason for alarm. I have NEVER broken a Norvel crank. In one post several years ago, I thought I had but it turned out to be a WASP crank. And I did break a few Brodak/CS cranks on diesel but not ever a Norvel crank.

Stewart,

Now, don't get me in trouble. [X(] To be fair, since I got the feel, I haven't bent a rod on any Norvel in years. This case was an exception and really, illustrates that you have to goof big time to do the damage. A teaspoon of fuel is an ocean of prime. Two or three drops is all it takes, amazingly enough. And again, the compression setting must be found with no fuel in the tank. Foolproof and easy to do. But in a way, you're right. I too puzzle at other engines with unnecessarily light cranks. Installing virtual beams into Norvels did NOT reduce performance in any way. Pictured below.