RE: Sliver swallow fuel
Matt, Silver Swallow engine instructions recommend initial break-in using the 1 : 1 : 1 mix of ether, kerosene and castor, but for a well-broken-in engine they suggest a mix of 32.5% ether, 40% kerosene, 25% castor, and the remaining 2.5% an ignition improver. Davis 1/2A fuel should certainly have plenty of ether - very small diesels like a lot of ether! It should also have very suitable kerosene and castor %s, and have a good ignition improver. Ignition improvers are hard to get, and can be pretty nasty chemicals to handle by themselves. Blended into fuel already, no sweat... If your Silver Swallow is never-run brand new, an ounce extra castor per pint should cover the mfr recommendation about extra oil for early break-in. And, one pint would probably cover the intial break-in running time... If your engine has been run in already, get any of the fuels mentioned in this thread and go to it. Bob Davis has an excellent guide to the care and feeding of diesels, as Does Eric Clutton (Dr. Diesel), the US Rep for British PAW diesels. I have a pink head 2.46 or 2.47 SS. At least 30 years old, not in constant use, but still a dependable great runner and easy to handle. Luck!
Posted on: 11/4/2009 3:24 PM by Author "Lou Crane" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=9228027

RE: Fox 35 stunt eng setup issues
Jayseas, Sorry for the long delay in answering about a larger diameter spraybar costing power from a Fox 35 ... (Got diverted to other things that took mucho time.) It's mostly theoretical, since reduction in effective throat area [u]will[/u] affect power at the top end, but not much where we generally set a Fox 35. Fox 35s, run as we usually do, can last a long time. Run them much above 13,000 RPM and they don't last too well. So, we stay around 10,000 RPM max, with plenty castor... The original Fox 35 needle, or at least the early one Fox made, has peculiar handling. (I think the very first Foxes used a Perfect or Kap-Pak Universal, or something like it, back in the early 1950's... Both of those companies are long gone. ) Over the years, Fox production precision has, shall we say, varied. It's been MUCH better the past 10 or 15 years... What complicated the 'standard' flat-one-side Fox NVA was often too loose a fit between the threads on the needle and in the spraybar body. That allowed motion inside the spraybar, around the jet holes, which may have changed the setting intermittently, and made fine tuning a setting iffy. A simple partial cure for that was/is to cut a snip of fuel tubing that will still be compressed at running settings. Slip it on the needle, between the inner knob and the spraybar. This does two things: the compressed fuel tube 'loads' the threads into a snugger fit, and the tubing acts as a seal against air leaks. The flat tapered needles also seemed to vary the setting as you sneaked up on what you needed - almost as if it went richer when the flat faced one of the jet holes, then leaner, within 1/8 to 1/4 turn, as it more like blocked both, then richer again as you turned it leaner. Once you got closer to a final good setting, the stair-stepping didn't seem to matter as much. It was getting there that took too much trouble. I like the OS or ENYA NVAs. They are close to the stock 1/8" OD spraybar diameter, and are beautifully progressive.
Posted on: 11/4/2009 2:58 PM by Author "Lou Crane" in the forum "Control Lines"
http://www.rcuniverse.com/forum/fb.asp?m=9227986

RE: Fox 35 stunt eng setup issues
The Hobby Fasteners item, by all means! Both are of excellent quality, but I'd suspect the ST NVA is a bit larger in diameter. The Fox Stunt 35 doesn't make great thundering gobs of power with the stock (1/8" diameter) spraybar; why close the throttle to half with a spraybar of almost 1/32" larger diameter? Hobby Fasteners makes?made their NVA specifically for the engines listed. And at that price? No question... (It's bound to creep up, ins't it?)
Posted on: 10/22/2009 5:52 PM by Author "Lou Crane" in the forum "Control Lines"
http://www.rcuniverse.com/forum/fb.asp?m=9194190

RE: Foam
Jayseas, Most foam used for models is cut by hot wire from larger blocks, usually insulating polysterene stuff. Chain hardware stores may carry that in 1", 2" or thicker slabs up to about 4' by 8'. There are a few special foam materials that can be cut with knife or saw - and the smooth blue insulating foam often seen in house construction cuts and sands nicely (and can also be hot-wire cut.) More likely to find the blue foam at a homebuilding supplier than a hardware chain store. The foam block materials come in different weights: Common styrofoam is around 1 lb per cu ft. The blue foam is around 3 lb/cu ft. The specialty hobby foam materials? Not sure... Styrofoam is about the least strong, but the shaped foam pieces are almost always sheathed in thin balsa sheet, other thin veneers or occasionally in fibreglas and carbon fiber "layups." There are a few other plastic foam materials - like those used in meat trays - which you can see a lot about in RC Park Flyer topics in model magazines. I've never used it, but, for instance, AMA's current Model Aviation mag has an article on suitable adhesives for this stuff. It cuts with a sharp hobby knife, and possibly also with scissors... Larger RC ARF models may include part of their structure (e.g., wings, tails) built around hot-wire cut foam... You'd need some sort of a controllable transformer to get a length of wire to the just-right temperature to cut block styrofoam cleanly. That, and a few special tools, and good templates to follow, and some useful experience, and good ventilation (heated styrofoam fumes can be toxic), and some useful experience. The wire is usually held by a frame that keeps it stretched tight, and allow connecting to the transformer. Hot-wire foam cutting is not something to dabble in for one use; it requires a bit of involvement and persistence to get best use of. For CL, most foam has been used as a form to have thin sheet balsa glued to, to build wings and tails. A month or so ago, Flying Models mag had a very innovative article explaining how to shape the wing surface by gluing it onto foam, in a method strong enough that it didn't need the foam. So, the guy used the hot-wire INSIDE the sheeting, to CUT OUT most of the foam! The model in the example was a large stunter, so BELIEVE it had plenty of strength! Are you starting to regret asking? [:)]
Posted on: 7/28/2009 12:34 PM by Author "Lou Crane" in the forum "Control Lines"
http://www.rcuniverse.com/forum/fb.asp?m=8970761

RE: Crashing problem
Jayseas, Don't let that discourage you... The Fox 35 has been around a lo-o-o-ng time. It isn't perfect (understatement?) but it can still do a good job. A uniflow tank, running properly, can be dead solid down to the bubbles at the end of the flight. Slightly off, and particularly with a Fox 35, it can cause a very noticeable difference in the run between upright and inverted, insides and outsides... General rule that works pretty well: the end of the uniflo tube inside the tank should be about 1/4" above the center of the intake. It may take a bit of tweaking on a particular model, and with a particular example of the Fox. (Some of them differ.) I notice, I think, that the tank is/was bolted to the fuselage in a way that you couldn't adjust its height up or down. Suggest that next time you build in a way to let you do that... HOW you run a Fox 35 can make a difference, too. It is famous for the '4-cycle/2-cycle break' type of run. That can be done. If the engine was too lean, going gangbusters in 2-cycle all the way, it may have leaned out high on the flight circle, or reacted too much to a slight misalignment of the tank height. The Fox also has a nasty habit if it is run too rich... Nice grunbling 4-cycle, but when you loop it, it can break too much into 2-cycle and cut out. An ideal launch needle setting, if everything about tank height is close or right on, is warbling between 2-cycle and 4-cycle, mostly in 2-cycle with fairly frequent 4-cycle burps. When everything is right, the model settles to a strong 4-cycle within the first level lap, and breaks into 2-cycle when you maneuver. (It should also break back to 4-cycle after a maneuver is finished.) If you have fuel with at least 25% castor, and from 5% to 10% nitro, a good hot plug and a prop that is neither too much or too little load (say a TF Power Point 10-5 or 10-6), you should be able to dial-in tank height so it will fly well and consistently. Edit to add: That 1/4" starting point is for profiles. For upright or inverted engine, full-body models, a 1 inch high tank sitting on the mounts (uniflow vent end inside at 1/2" above the mounts) works very well. Besta luk towards that!
Posted on: 7/14/2009 6:58 PM by Author "Lou Crane" in the forum "Control Lines"
http://www.rcuniverse.com/forum/fb.asp?m=8933507

RE: Unerstanding Purpose built Verses Conversion
Greg, To yours of June 26, I know that it is possible to measure in-air RPM, as CL speed and racing fliers do. It is not simple, nor usual in the gear most of us haul to the field... Last I saw it done (in CL Speed), it involved a fairly high-fidelity tape recording, from the flier's center location (to reduce Doppler frequency shifts) and a program in a laptop computer to convert the recorded sound frequencies to RPM. Now, that's too technical, for me at least... [8D] Andy, to yours of July 6: You wrote: "...most times a reduction in bore helps..." Am I correct that the 'bore' you refer to is the choke ID? Also, agreed, some mass-produced glow engines may not be sturdy enough for dependable conversion, without needing to be nursed along like a feeble old maid... THIS is probably where the charge that DDD heads break engines started. Bob D's first commercial product was the Cox .049 conversion head - teflon seal, loose "contra-piston," large thumb-screw comp adjuster... It wasn't Bob's head that broke shafts. It was the users who expected the "usual" 16,000 to 18,000 RPM on 5" props, instead of the more suitable 10,000 to 12,000 on 7" props. Bob's stronger shafts have about ended that problem, no? However, most of the schneurle ported, taper-cut ABC/AAC/ABN engines that are almost universal now, are much more sturdy than the reed valve Cox .049s of the 1970's, when Bob first released his head for [i]them[/i]. Even so, one of our regulars in this forum has managed to suffer shaft breakage on a highly reputable glow .40 converted to diesel. I know JT didn't intentionally set up any conditions that would cause the breakage, so I'll write that off as an "off label use" (as they say about medicines) that the engine could not handle. Exceptions prove??? To some others in here, allow me to paraphrase Jack Nicholson in a movie: "The TECHNICAL? You [i]can't handle[/i] the TECHNICAL!"
Posted on: 7/6/2009 9:39 PM by Author "Lou Crane" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=8911922

RE: Tanks
Jim, and much obliged Downunder, that fit right in... A uniflow plumbed tank is much more sensitive to "relative tank height." I mentioned the advantages of getting it right, but not the reasoning. But, first, yes - the forward facing vent tube end is exposed to some ram air pressure as the model flies. Not much... And, whether the vent air provided into the tank interior is below local atmospheric pressure, at that pressure, or slightly above, the reference point that the engine 'senses' is the inside tube end where the bubbles come out. For simpler handling of a hard (metal) tank, I usually take pains to get that uniflow vent tube at exactly half the height of the tank shell. That way I know where it is, if flight experience shows it isn't quite right. This location is key, as several who use converted plastic bottle RC tanks 'trim' the run by twisting the uniflow vent tube to a different height inside the plastic bottle. Nothing else needs to be shifted. Say the engine runs richer inverted and outsides than upright and in insides... The tank is too "low" when the model is upright. The engine has to draw fuel uphill, even if only a small distance. That same distance is doubled when the model flies the other way. If we can call the "perfect" tank height a sweet spot, in this example, the vent end in the tank is some distance [u]below[/u] the sweet spot in upright/inside conditions. Inverted and outsides, it is that same distance [u]above[/u] the sweet spot... Since I have the uniflow outlet at a known height inside the tank, I can shim the whole tank, in this case up with the model upright, and see if it needs more or less to get it the same both ways... And uniflow tank venting can be VERY sensitive to this, particularly for richer-running 4/2/4 engines. With muffler pressure, the difference is less than with the forward facing external tube open to the airstream. With more recently designed engines, almost invariably ABC/AAC or ABN's designed for RC then converted for CL use, their most natural running mode is somewhere in their quite wide range of 2-cycle RPM. ...And most often they run on muffler pressure, so the problem is quite a bit less. Even so, a careful ear, and a sensitive hand can feel the unavoidable variations in power when a uniflow tank is not just right. I've developed a routine to check tank height before first flight on a ukie. Shortest description: Hold the model with the fuselage centerline level at all times when checking... Start the engine and rotate the wings to vertical, outboard tip down (re-read line above...) Set engine slightly rich, so you can hear - or better, tach - RPM changes. (Fuselage level, right?) Rotate the wings to about 45° from vertical, say cockpit-side up for the starter. Note RPM by ear, or better, by tach. Rotate wings to the same angle, cockpit-side down, and recheck RPM. (Keeping fuselage centerline level.) Repeat a few times to be sure any response is consistent, and that you can recall which way it went. Now, you can relax that First Commandment about level fuselage centerline... Turn model nose-down, inboard-tip down to uncover the fuel pickup in the tank. If it doesn't shut off quick enough that way, you can cap an open uniflow external tube with a finger... Your test wig-wagging crudely represents the [u]angles[/u] of the "gravity vectors" the model feels in flight. NOT their intensity, just their direction. And, about 45° is both far enough to cause a response difference if things aren't just-so, and easy enough to approximate on both sides of vertical, outboard-down. RPM drops from richening on the side where the tank is too high. Conversely, RPM rises when the tank is too low in that attitude. Adjust the height accordingly, and run thru the same sequence to see if that was enough or too much. After two or three times through this process, you should be close enough that, at least, you won't flame out or starve out on a first flight. There is no hard and fast rule based on the layout of the engine type for the relative height of spraybar and inner uniflow vent end. Most individual engines of of a mass-produced type, e.g., Fox 35, or OS 40FP, or 40LA, share the same tank preference, but I wouldn't guarantee that the solution for an LA40 works with an FP40. I built a test bench which allows me to check unfamiliar engines for tank height preferences and sensitivities.The commercial engine mount (J'Tech) mounts on a board to hold the tank (adjustable as to height in the relevant direction, sidewinder is different from upright or inverted). The board can be rotated, roughly about the crankshaft centerline, while the engine is running. Testing is similar to the wig-wag process above. Inspiration for the wig-wag and the bench followed an experience with an engine that needed the reference height more than 3/8" different from usual practice. ...caused a few crashes... But when the engine was sorted out, it was excellent!
Posted on: 7/5/2009 3:41 PM by Author "Lou Crane" in the forum "Control Lines"
http://www.rcuniverse.com/forum/fb.asp?m=8908321

RE: Tanks
And, Jim (Jayseas, that is) the [u]reason[/u] the uniflow venting does what it does is... - The fuel's effective "gravity head"... Picture a town water tank, a big bubble supported fifty feet off the ground... The weight of the water provides a pressure into the pipes down at ground level, right? When we fly CL, centrifugal force and gravity combine into what could be a single force pointed out and slightly down, with the effect of 3 or more g's of "weight." Like the town water tank, the effective gravity head is [u]from[/u] the [u]surface[/u] of the liquid open to the air around it, to the pipes which carry the liquid away to where it will be used. The traditional "over and under venting tank" in the diagram has its fuel head at the surface of the fuel inside the tank, since the vent tubes are at the inside wall of the tank, and uncover to being both open shortly after takeoff. As the fuel burns off, the fuel surface moves nearer to the outer wall of the tank. The "height" determining 'gravity head' gets smaller. There's less pressure as the surface falls toward the pickup. That's why they run rich at first and lean out over the course of the flight. The uniflow venting, on the other hand, sets the vent height that releases air into the tank interior very nearly at the same "height" (in the slanted direction of that equivalent force I mentioned) as the pickup tube. That "height" makes the fuel surface location irrelevant, since the tank is sealed, except for the uniflow vent end and the fuel pickup. NO outside air affects the fuel, except what enters the tank through the uniflow tube, and then, only at THAT height 'above' the pickup. (Along that slanted equivalent force direction.) Uniflow tanks are not all sweetness and light, though. It may take some effort to place them where they work best. If they are too high, the act like an enema bag, pouring fuel downhill to the spraybar. If they are too low, the engine must draw fuel 'uphill' - like with a leaner needle setting. Once the uniflow tank is the right vertical height for the engine, not only is the same setting held through almost all of the flight, but it is the same upright and inverted, and in inside and outside maneuvers.
Posted on: 7/4/2009 4:01 AM by Author "Lou Crane" in the forum "Control Lines"
http://www.rcuniverse.com/forum/fb.asp?m=8905361

RE: adding castor?
Jim, Sorry you are backing out on this. As I see it, several of us are speaking of the same thing in slightly different ways. If I understand Downunder's point, the flammables in the fuel provide the power. To get the same power, you have to burn the same quantity of methanol (and nitro, if it's part of the blend.) The oil content doesn't affect that, but in a low-oil% fuel, more of the methanol (and nitro) are in the mix drawn in by the engine in each revolution - presuming that all the fuel ingredients are vaporized or atomized to the same degree as they go into the engine. With a higher oil percentage fuel, you need more total fuel to enter to keep the same quantity of the flammables available for burning. Richer needle, in other words, and often more fuel consumed per minute. And oil absorbs heat from the engine metal and from combustion. Burning is supposed to produce heat, and that heat is our power. By reducing the heat released, in proportion to how much the oil absorbs, and by taking up space that could otherwise have been filled with the combustibles, the oil content damps down the combustion and thus the power production. We live with that, since without oil, our engines would quickly become expensive, funny-looking, welded-solid paperweights... These ARE definite effects on how a fuel runs. Adding more of any one of the main ingredients, without changing the others in the same proportion, also has effects... To compare: If a fuel is 20% Nitro and 25% oil, the rest is the methanol - 55%. If it is 20% nitro and 15% oil, methanol makes 65% of the fuel. It is an interesting algebra exercise to find how much oil to add to bring its % up from 15% to 25%, because the oil added increases the total fuel volume. Example: If you start by adding 10% of the original volume as oil, think of it this way. You started with 100 "%-units" of blend. That means 20 units of nitro, 15 units of oil and 65 units of methanol. Add 10 units of oil. Total volume of the blend is now 110 units. Nitro [u]units[/u] don't change. Methanol [u]units[/u] don't change. Their [u]percentages[/u] do, however. The 20 units of nitro in 110 total units of volume isn't 20%; it's 18.2%. The 65 units of methanol in 110 total units of volume isn't 65%; it's 59.1%. Even the oil % changes: 15 units + 10 units is 25 units in 110 total units of volume, which is not 25%, but 22.7% Add up the new percentages: they equal 100% of the new total volume. And, you have that extra 10 units more than the original total fuel volume to deal with... You can doodle out a few more guesstimates of how much oil to add to make 25% of the new total volume in a few more runs with the same procedure, and also figure the effective nitro and methanol % that result... And, Bob, Hi! There may be a fallacy about the synthetics leaving the engine unprotected/unlubricated if they burn away during combustion... Sure, some part of the synthetic % does burn, but only WHILE it is exposed to the burning methanol and nitro. The power stroke of the piston, in other words. ...When the piston is moving down, uncovering the sleeve where nothing is sliding in it. The next bypass charge sprays the interior of the sleeve with a fresh dose of cool oil for the piston to ride up on during the compression stroke. Part of the reason synthetic blended fuels are popular, may be that many sport RC fliers prefer that their models do not become so oil-coated as we CL fliers are very used to putting up with. The synthetics are excellent oils, but not for all uses. Similarly, all-castor as the oil% is not ideal for certain aluminum piston ABC/AAC/or ABN engines. Castor's tendency to form a varnish coating on cast iron pistons helps those stay lubricated and sealed; tapered-fit brass or aluminum sleeves have no room for such a coating... Finally, if all else fails, re-read the engine manufacturer's instructions. Mfr's certainly won't tell you to do something that will make their engines look bad...
Posted on: 7/4/2009 3:35 AM by Author "Lou Crane" in the forum "Control Lines"
http://www.rcuniverse.com/forum/fb.asp?m=8905346

RE: commerical model diesel fuul??
Fiery, Thanks for redirecting the thread to its original subject! If various national agencies - driven sometimes by agenda extremists totally uninterested in ANY other viewpoint than their own - arbitrarily punish, fine and oppress anyone differing from their agenda, many unintended "victims" suffer. I'm all for wise stewardship and use of what nature puts at our convenience... Others may not be... Where I live, it is possible, with a bit of effort - not much, really - to find the ingredients needed to brew my own diesel fuel. I hope this is also the situation for most of us... That frees me from arbitrary excess cost shipping, from a restricted range of commercially profitable blends (No opposition to profit! Any profit is taxed heavily, for one thing, and some profit MUST occur, or a firm cannot be sure to survive the next fiscal quarter...). I wish it were that easy with glow fuel...
Posted on: 6/30/2009 2:28 AM by Author "Lou Crane" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=8893755

RE: Unerstanding Purpose built Verses Conversion
Greg, ...selectively, so as not to annoy you more than necessary... I believe I wrote the compression [u]setting[/u] was not much different. The space in the combustion chamber, between the power piston and the contra-piston, is small. The contra-piston screw thread is not variable. At high RPM compression settings, a quarter turn MORE compression changes the compression ratio more than the same quarter turn toward LESS compression. Is that agreeable to you?
Posted on: 6/27/2009 7:44 PM by Author "Lou Crane" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=8886573

RE: Fox? Tower? what is it?
Hemi and Cpnjohn... If you ever get a look at Fox's 25BB schneurle, you won't find any brand mark on that, either. And it doesn't even [u]look[/u] like any Fox you've ever seen. VERY nice engine; plenty power, and even a more "acceptable" looking two-needle carb on the RC versions. If they were to switch it to ABC or (dream on) ceramic, and promote it with some notable names flying it, our economy would be dragged back to the black-ink side of the ledger overnight!
Posted on: 6/24/2009 6:24 PM by Author "Lou Crane" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=8878048

RE: Unerstanding Purpose built Verses Conversion
Greg, Agreed, I haven't chased through the web looking for those specific values. Even Brake Specific Fuel Consumption is pretty arcane for our uses. We can measure fuel consumption per unit time, but in-air RPM is almost always an estimate, as is the prop load at the relevant airspeed. How, then, calculate brake horsepower? The odd condition of having such blended fuels, IMHO, makes it more difficult to state reliable specifics. So much depends on the complex blend of fuel components, user factors, engine, setting, prop, altitude, humidity, temperature, phase of the moon, etc. Not so sure I can buy the idea that "modern" schneurle engines are fundamentally different/better than engines of 10 to 15 years ago, when Mike Billinton ran engine tests for AeroModeller(RIP), and I think I'd seen some of his work in an occasional MAN since. He tested ABC, ABN, AAC schneurles more than any retro crossflow engines. Nice work. He didn't reduce torque and HP curves to idealized, smooth approximations. Still, invariably, his peformance graphs indicated torque peak RPM at moderate values, however high the engine could wind out before HP peak RPM... Exceptions, too. He also ran some tests with tuned pipe boost, and graphed the torque and horsepower consequences for several different max boost and max degradation conditions from the pipes... So far as "effective" volumetric efficiency - it seems to me that in a given engine there is one optimal "gas-flow" zone (air and vaporized fuel being considered gaseous) where the volume transferred is optimal, where pumping losses are best countered. THIS is what I expect more rigorous, complex testing and analysis would find to coincide closely with the engine's torque peak RPM. Seems to me to be a matter tied to the internal sculpturing, paths and instantaneous flow velocities in several small zones... which we generally don't mess with... Pipe resonance effects superimpose on this 'natural' flow. The actual compression ratios at 10K and 20K are more rather unrealistic numbers for the average user. They aren't very far apart on the compression lever, anyway. The loads involved are more concern to the engineers who develop engines, not to most of us at the user-end. Of course, any method of ignition can serve engines designed to whatever RPM conditions are sought for. Design from blank paper (monitor screen?) works best, if your demands are very far off 'the usual'. PAW engines are pretty sturdy, to begin with, so re-engineering to withstand loads may not be a factor. Fit, clearances, sleeve and shaft timing, assembly alignment and most suitable part weights within the factory tolerance spread are easier to optimize when you have the entire batches of a production run to cull through. In addition, PAW factory surely knows what further touches to porting best serve combat and racing. The performance differences are definitely there. But PAW is not a best example of purpose-built high-RPM diesel engines. For combat, perhaps, with the local popularity in some areas of Nostalgia Diesel FAI Combat, but all first tier current FAI Combat engines are glow these days. TR diesels turn in the vicinity of 30K, and get plenty of laps per tank - now, that's amazing! The ENYA 25 SS-D I'm breaking in shows ~10,000 RPM with about a half-hour on it, on an 11-6. I expect the factory numbers are possible, eventually, but are not ordinary flight settings. BTW, I live at ~5,000' above sea level, but diesels are less susceptible to altitude effects, or better said, the adjustments allow compensating for those better. ADDED: Went back and read your links. John Modistach's report on the 25 SS-DTV is interesting and well written. The 25D I have is the non-TV version, although the effective choke areas are similar. Also, after the first 10 minutes on 1-1-1 fuel, and a few minutes on the 3-3-2 blend cited, I'm running 5-3-2 blend, with the 50% being kero. The VicStunt report on the FORA is interesting, too. I'd expect higher RPM... Haven't spent much time browsing VicSTUNT lately... Thanx!
Posted on: 6/24/2009 6:08 PM by Author "Lou Crane" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=8877985

RE: Fox? Tower? what is it?
Hemikiller, It is the first series of Fox "banjo-back" schneurle 40s and 45s from about 1973 or 1974. This one is a 40, as is visible on the mount lug. It is a lapped-piston, plain-bearing engine - the BB versions came a bit later... These ran well, and Fox developed them further over several years, up to and including the current 46 and 50 BB "big case" schneurles. The shiny, tumbled casting was the finishing method Fox used for all engines in that era. Later 40 and 45 BB Schenurles had a nicer light, satiny bead either blasted or tumbled finish. Fox eventually offered an adapter spigot for the Perry carbs, but the adapter on yours does NOT look like the Fox item. There wasn't anything wrong with the stock Fox carbs, it's just that they were different to set up than the ST MAGs, Perry's and OS air-bleed types. A few guys who couldn't be bothered to learn how to set the Fox carbs gave them a bad rep. As I said, they weren't as 'even a caveman can do it' simple as the other types, but worth the effort when you did. Provided the engine has lived on enough castor oil in the fuel, if it has been run much, it should run great and last until you're tired of looking at it.
Posted on: 6/23/2009 4:55 PM by Author "Lou Crane" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=8874748

RE: Unerstanding Purpose built Verses Conversion
Jim, We need to refresh our thoughts again? In our case: Power is the rate of doing work. Torque is the force that does the work. Agreed? A weaker [i]torque[/i], applied more times a second, say, could make more [i]power[/i] than a stronger torque applied less often. Whether that is true depends on the, in effect, Force times Rate at which it is applied. A smallish diesel may be able to turn a largish prop at the same RPM as a larger glow engine. That only says that both engines are producing the same torque at the same rate (RPM) on that prop. Recent example: ENYA's 25BB diesel cites 9,000 RPM on a 12-5 or 12-6 prop. Many stunt-suitable CL 40's might not be able to do that. The difference is that on a lighter prop load, the same 40's can run higher RPM, produce more [u]POWER[/u] while the ENYA 25BB-D may need destructively high compression settings to try to match them, on those smaller props. And, relevant to Greg's comments: 1.) yes, of course, volumetric efficiency, as a practical thing, must relfect the trapped volume, and, 2.) We CAN rev-out glow engines because the methanol-based fuel WILL burn at less than ideal conditions far longer than a kerosene-based fuel can. The torque curves we used to see in the P.G.F. Chinn engine tests (or those by Billinton, or way back, Ron Moulton and Ron Warring) showed torque and horsepower by RPM. Diesel torque curves reached high values around 9,000- 10,000 RPM and fell away gradually. Glow engines torque curves fell more rapidly from peak, but the methanol made the result productive of higher horsepower for a lot more RPM range. We could probably wind up typical "built-as" diesels if we insisted, but the transfer channel volumes in so many of them are too small to keep it positively productive, however well they serve around torque peak. And the excessive compression settings, to advance the ignition point suitably, would be very punishing on the engine.
Posted on: 6/23/2009 4:38 PM by Author "Lou Crane" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=8874697

RE: Unerstanding Purpose built Verses Conversion
Greg, sorry for the tag team delay: just got back in here.... I don't have the heat yield numbers to hand, if they exist. The matter is a bit more complicated than lets us easily find the yield of our fuels as mixed. It is the KEROSENE and METHANOL contents of the respective fuels that differ. ASIR, methanol - [i]ideally[/i] - yields somewhere around 10,000 BTU per pound, and both kerosene and pump gasoline are in the 19,000-21,000 BTU per pound range. (NOTE: the fuel yield testing is by pounds of fuel per pounds of (either air or) oxygen. Not sure which, but for chemistry is would seem oxygen, as nothing else in our ambient air takes part in combustion. A complication, then, as there's only around 20% oxygen in air...) Some other complications: Kerosene in many diesel fuels goes a bit over 50% by volume; methanol in most glow fuels is reduced by the oil fraction and the nitro fraction. Oils, say 22%, nitro 15%. That's 37% accounted for, leaving 63% for the methanol. ...By volume, most often. Nitro yields combustion heat, too. Haven't come across its [i]ideal[/i] yield in BTU/lb, but it may not be as high as methanol, since it is much denser than methanol - something like a Specific Gravity of 1.14 for nitro and around 0.8 for methanol. Since most fuel makers mix by volume %, the [u]weight[/u] fraction of nitro is higher than its volume fraction. Then there's the 'damping' effect on combustion from having (we hope!) [i] non-burning[/i] oil mixed with the flammables... AND, the reason I stressed the word [i]ideally[/i] each time, so far, is that we don't burn these fluids in the most ideal way, the way the heat yield values were determined. That hides behind that weird word "stoichiometric", which as I understand it means all the combustible fluid is burned in all the oxygen available for combustion. ...No unburned fuel left, and no un-consumed oxygen, in the exhaust gases... We may come closer to stoichiometric with kerosene, since it does not tolerate as wide a range of fuel/air mixtures as methanol. But remember all those other factors, including that the ether in a diesel blend also contributes some heat during combustion. Again, I haven't seen a number for ether's yield in BTU/lb, but expect it is much lower than kerosene's. Ether is also much less dense than kerosene, so its weight fraction % is even less when the fuel is mixed by volume %. And, since nitro brings its own oxygen to the "fire," the glow engine's breathing capacity is assisted directly. Also, we run glow engines richer, as a rule, than diesels. We use the evaporating chill of methanol to help cool the glow engine. Kerosene doesn't chill as it sprays into the intake, most likely because it does not evaporate as easily. In both modes, the oil does help to cool things some. When we see visible exhaust vapors, we know that some fuel or fuel and oil passed through the engine without burning away, leaving the metal uncovered. (Actually, that fear may be a fallacy, even if the oil burns. When the oil is exposed to the combustion "flame" the piston is on the way down to BDC. Through BDC the fresh charge is sprayed into the cylinder, ready to lube the piston on its way up to TDC.) IOW, we use the fuels according to the ignition type involved. We can pass quite a bit of unburned methanol and oil through a glow engine, even when running fairly "lean." "Diesels" need to be leaner because of the narrower tolerance to fuel/air ratio and because the required high compression ratio leaves little room for globs of pressure-precipitated fuel... If everything were simple and easy, our hobby wouldn't be much fun or challenge, would it?
Posted on: 6/23/2009 4:11 PM by Author "Lou Crane" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=8874618

RE: Unerstanding Purpose built Verses Conversion
Greg and Martin, Sounds like we're all pretty much agreed. I just rambled on about the internal processes. You BOTH identified the practical side - that converted glow engines' throttles match the rich mix tolerance of methanol glow fuel better than the more finicky mixture tolerance of kerosene-based diesel fuels. Whether it means no gain from throttle above 2/3 or 3/4 - which I've also observed - or it suggests it may be a good idea to replace the stock OEM carb with one for a smalller engine. How much smaller? Hmmm. Perhaps the torque performance increase we see with our diesels would indicate that. If a .25 diesel can turn a larger prop the same RPM as a .36 or .40, would that suggest a better fit for diesel-converted .36 to .40 engines to use a .25-size carb? This example would match the favorable torque around torque peak RPM from the more potent kerosene heat-yield. Remember - torque peak RPM for any engine is very likely to be where the volumetric efficiency is best. ...Where the engine can take-in and exhaust fuel-air mixture most efficiently. Both the ENYA restricted carb, and Bob D's suggestion of a 'NASCAR-plate' type restrictor seem to address this. Whatever, diesels are very gratifying to run. I thank any and all who keep it possible for us to get and use them!
Posted on: 6/21/2009 7:38 PM by Author "Lou Crane" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=8869758

RE: DDD heads destroying engines?
All, The DDD conversions for the reed Cox engines f'r shr do better with Bob's stronger crank. Also the teflon(r) head seal piece is another safety feature. Too much compression and too high RPM will burn it through faster. The answer? Go to a larger prop that moves the compression setting softer, and gets you the thrust you need at lower RPM. General rule for diesels, as-designed or converted: bigger props turn less RPM, less RPM means "retarded" ignition point, "retarded" ignition point means less compression. To go with the lower compression setting, a bit richer needle is a natural. So, a lot of the problems some report with the teflon, 1/2A DDD heads is likely from trying to get glow RPMs that the DDD setup was never meant to reach. So, use what you got the way it was meant to be used. Off-label prescriptions don't always work, rather, usually DON'T work.
Posted on: 6/20/2009 12:06 AM by Author "Lou Crane" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=8866147

RE: Unerstanding Purpose built Verses Conversion
Bob, An excellent summary of the timeline! Thanks! There are a few other differences, between designed-as and your excellent diesel-conversion types. I go on and on, occasionally, here and other sites, about the (?) "port volume" (?) conditions for glow or diesel [u] fuel [/u] use. In short, as I see it, glow fuels, based on methanol and glow ignition, are extremely tolerant of rich mixtures. 1) Methanol can - usually does - vaporize well in the intake flow. Kerosene-based diesel fuels probably do not do that as well, and kerosene has a much smaller tolerance for rich mixtures. These ideas allow glow engines to have relatively LARGE bypass volumes - the vaporized methanol stays vaporized. And it will still burn at very rich fuel/air mixtures. 2) Because of 1.), above, most moderate RPM, designed-as, diesels I've been inside of have quite small bypass channels. They are large enough to do two things - first, they CAN supply enough air/fuel mix to the combustion side at the moderate RPM the engines seem happy at, and second, the small channels keep the flow speed up to where the kerosene, whether vaporized or in the form of extremely small droplets, doesn't get a chance to slow down and collect into larger droplets. Vaporized fuel, or very-fine-droplet mixed fuel burns better than a smaller number of large globs... 3) Again, referring back to my opinions in 1.) and 2.), above, all our model engines are essentially air pumps. For methanol-based fuels, we can get away with, and gain from, overly rich settings. Methanol will still burn productively at very rich settings. We can rev out, gaining horsepower, quite a way past torque peak RPM. Kerosene-based fuels, for one thing, cannot burn well, if at all, at excessively rich settings, and for another - with the higher compression ratios needed for "diesel" combustion, there isn't room in the combustion chamber for large globs of liquid fuel. Can you say: hydraulic lock? ____SO, the ability of the engine to pump air works with methanol for more horsepower at higher RPM, but limits the amount of kerosene-based fuel it can burn... 4.) All this aside, the "diesel" system is tolerant enough of wierd conditions that the designed-as diesel runs well, economically and strong at around torque peak RPM (where the volumetric efficiency of the engine is at max.) The diesel ignition is also tolerant enough of things that your conversions of the over-breathing designed-as-glow engines do fantastically well - running well, economically and strong at torque peak RPM and somewhat above. (And, with appropriate props, can pretty well match any glow engine performance as long as we don't go too rich with kerosene.) ASIDE: In CL Stunt, engines like the classic Fox 35, have been "improved" by blocking-off part of the bypass volume. That keeps the bypass flow speed up, for more turbulence (i.e., better mixing of the fuel-air charge), and makes it less sensitive to g-loading effects (remember- fixed throttle, no carb, g-loads from 1.0 to perhaps 30g.) I wonder if there would be any effective gain for one of your converted engines to do something similar to an over-generously ported designed-as glow with your conversion head? If so, I'd guess it would mean more stump-pulling torque around torque peak RPM. rather than an extended RPM range. They are a bit different, but both approaches work - as-designed and head-converted diesels, for one, and glow and diesel engines, for another. Glad you're still making it easy, simple and successful for so many glow-engine users to learn that diesels don't smell bad, just different...
Posted on: 6/19/2009 11:11 PM by Author "Lou Crane" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=8866032

RE: FOX .15 STUNT ENGINE
The first Fox 15 baffle I had was a "learning experience..." That was the first run of them in the mid/late 1950's, which had a finned, steel sleeve. Some, so I'd heard, ran well. Not enough, apparently as Fox changed to the die-cast , full-height crankcase with drop-in steel sleeve around early 1960s? Better, but not always, or for everyone. I've had a few that did quite well, if you allow for what they actually can do. Still considering one for a friend's current project... Surprised to hear it tows a Warlord better than a PAW 15! ...ANY PAW .15??? Hmmm... I seem to recall that my better ones like 10%-15% nitro, and 25% castor, on a light, clean 8-4 wood prop. Flight setting in steady-2-cycle, backed off just a bit from peak. The X and XX models were different from the main production version. I regret that the 2.5cc/.15 cu in size didn't catch on here as a sport engine size. Goodyear Racing and (in the USA) relatively few FAI Combat fliers wanted lotsa lotsa power.
Posted on: 6/2/2009 2:17 PM by Author "Lou Crane" in the forum "Control Lines"
http://www.rcuniverse.com/forum/fb.asp?m=8819896

RE: Foz .15BB or KB .20 Sportster conversion??
Franchi, I have no experience with a DDD K&B 20, but it is a solid and strong engine as glow. The Fox BB Schneurle 15 is also a nice strong engine when DDD converted. I'm not sure it would be comparable to, say, a PAW 19BR in a Sterling P-51 or Ringmaster. (The PAW 19BR has the usable power of a good Fox 35 Stunt in such a model.) I HAVE fown a Fox 15BB Schneurle/DDD in a 400 sq in original stunt profile - where it proved much more than adequate... That was a light model, however, lighter than I expect any recent kit of a Sterling profile to come out. Have fun, first, then sweat the details later...
Posted on: 5/13/2009 12:02 AM by Author "Lou Crane" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=8764456

RE: Davis Diesel hand starting , imposssible?
Franchi, Good luck on this... I'm serious on that, not being snotty. You know how to empty a flooded cylinder when an engine is in a model. If you think your LA 40 DDD is at all flooded, make those moves. After you're sure it is motly emptied out, back off the compression and see if it can be flipped fairly easily. Any fuel left inside will lock up the prop. Back comp out a bit more if that happens. You should reach a comp setting that will pop if there's any ether left in the stuff inside the engine. Allen keys for the comp screw make good markers for your running setting. Keep in mind where it should be running as you back off... You could even close the needle valve while chasing the ignition point. Diesels flood so easily that the fuel feed might be doing it without you noticing. Once you get it to pop regularly on priming (see below), reopen the needle valve. If it is in a model, [b][u]keep the nose up to prevent siphoning fuel into the crankcase[/u][/b] If it won't pop after 5-10 flips, comp backed off, try a few drops into the venturii and flipping it. If you backed off the comp too far, and this direct priming doesn't bring a pop, start bring the comp back up, about 1/8th of a turn at a time between priming cycles. Be ready to bring comp back up to, possibly beyond, your established running setting to get it to bit in solidly. As it warms up, you'll ease comp back to the established setting...
Posted on: 5/10/2009 7:04 PM by Author "Lou Crane" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=8757628

RE: Importance of engine break-in ?
Jorge, I don't know this engine, and have only limited experience of 4-cycle engines. Because of the valve train, 4-cycle engines have practically a built-in RPM limit. Too fast and valves float. Not good in a car, not good in a model engine... So, they do not speed up if the mixture goes leaner. I have heard that a safer way to set the mixture on a 4-cycle is with a tachometer. As the mixture is leaned from very rich you may find RPM increases at full-throttle. If so, you will see the RPM stop increasing at a certain value, even though you can make it leaner. My opinion: the [i]richest [/i]mixture that comes close to that RPM should be safer than a leaner setting... I've noticed that some engine manufacturers recommend less oil for their 4-cycle engines than for 2-cycles. Also, quite often, synthetic oils or blends of synthetic and castor are recommended. 22% castor seems a lot. What does the manufacturer recommend? How did the engine feel after it cooled down? Have you checked the valve clearances since the very hot run? Did the carburetor drum (or plate or butterfly) actually turn as the linkage was operated? (The linkage arm could possibly slip...) Does the cowl have enough opening for air to enter, AND a [b]bigger[/b] opening for hot air to leave the cowl? I hope the slow running was due to the carburetor arm slipping, and not to binding of overheated parts inside the engine. I hope your engine is still in fine condition, and that you have long and pleasant service from it.
Posted on: 5/10/2009 6:50 PM by Author "Lou Crane" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=8757601

RE: Importance of engine break-in ?
So, we have some strong opinions in here. That's fine. Some points still to be made? ALWAYS consider the manufacturer's break-in recommendations! If something goes wrong and you weld it into one expensive paperweight, you might consider blaming the mfr, and go to them for "satisfaction." (Some comments in other threads suggest that some of us DO think that way.) A mfr will be able to tell, and fairly easily, if the engine has been brutally abused, but nowadays would probably cave to prevent "bad press." I also check that a new engine has been properly assembled... You'd be surprised at some of the mass-production goofs I've caught before first run... And, again, I've seen occasional comments from people unhappy with an expensive engine when they found a head bolt or backplate bolt hadn't been properly tightened. Well, duhh, didn't you even LOOK at the engine before operating it? Proper torquing is important, too. You'd be surprised if you loosened all head bolts, checked how free the engine feels that way. Carefully torque the head back in with a consistent sequence, checking that you haven't introduced any bind, after each 'rotation' through the sequence. Modern engines are more substantial than those of the 1940's and 50's, but they can still suffer from bad torquing - consider: brass is not as hard as steel and most sleeves today are based on brass... Type of engine makes a difference - and the mfr generally suggests what they are confident will work reliably. Examples: Some engines have synthetic oil only recommended; some recommend 0% nitro fuels; some say bolt it in and go fly... The differences I'm familiar with after almost 60 years of using glow, diesel and occasional spark engines seem to work just about every time: Lapped iron pistons in steel sleeves - bench break-in, outdoors. Significant castor oil % in the fuel. Short runs - just up to thoroughly warm - and good cool-down before the next noise. Slobbering rich for first one or two runs, then gradually leaner over the next several. (First, polish in the rod bearings. Then go for the longer term heat-cycling and burnishing-in without galling anything.) At first sign of anything wrong developing, it is much easier to yank the fuel line off a bench-mounted engine... Ringed engines are almost the same, except that the critical wear zone on the piston is only the height of the ring(s). If rod and shaft wear in properly, that small ring land shouldn't need as much run time to get durably happy... Non-ferrous engines (Aluminum/Brass/Chrome, Aluminum/Aluminum/Chrome. Aluminum/Brass/Nickel), imho, still need at least one brief rich run to help the rod bearings run-in. THEN do as most mfrs suggest: several brief runs just below 2-cycling or warbling in/out of a rich 2-cycle. Cool-down between runs. DON'T wind in the needle (HS needle with RC carbs) until RPM sags! Sagging RPM can indicate heat expansion is pushing fits toward metal-metal contact. We have oil in the fuel to prevent that... Why the difference? As Dar and others cited, modern CNC techniques allow cutting basic dimensions so that proper clearances only occur when operating temperatures expand the piston and sleeve the designed amount. Overheating these, when new particularly, can force metal-metal contact, which will gall finished surfaces, or wear away the designed dimensional fits. Loss of performance and power may not be a lot, but that's no way to help an engine work well for you for a useful length of time. Engine temperatures: Engines reach about the same running temperatures pretty much regardless of ambient temps. The heat comes from burning the fuel. The complete cooling envelope limits the top temps reached. Our engines are partially air-cooled. Other cooling processes include vaporizing the fuel through the venturii or carb. Methanol chills significantly on evaporation, and the crankcase directly under the carb or venturii feels cool even on an engine running pretty hard. Do not try this on an engine buried in the nose of a model! However, it is safely accessible on a bench. The chilled zone adds a nice heat sink that doesn't warm from running. Another process is heating the oil going through the engine. Most of it doesn't add much heat to the combustion, even if some synthetic does burn away. Castor hardly ever burns, so it leaves the engine with the heat it has picked up. ...Physically carries those calories somewhere else... (Castor can char, and coat the carefully generated dimensions on the sleeve and piston, so it isn't always best as the only oil for non-ferrous, CNC produced engines. It can be good in a blend with synthetic oils, which act as detergents to reduce charring and buildup.) A decade or two ago I was "breaking-in" numerous OS mid-size engines for an acquaintance's project that needed unquestionably settled-in ready-to-go engines. As many have commented, and occasionally the instructions will suggest, power and economy improve dramatically over the first 5 to 10 minutes of proper running. The first runs made for difficult starting, hot running and considerable dark matter flushed out in the exhaust oils. Economy was also pathetic... As these were modern, non-ferrous CNC made engines of well-deserved good repute, I understood the initial runs accomplished much burnishing of remaining machining tool marks and surfaces. (The machining was close, but not perfect.) Economy, handling and power rapidly improved as the oil cleared. BTW, I almost always hand-start engines on a test bench. It's a better "feel" for the engine's condition. Still have all my fingers, and only an acceptable scattering of small scars. ...Cautionary reminders to be careful, that I never got from an electric starter... ...Engines continued to improve over some additional running. The rate of improvement declines as you get it settled in. No sense just burning fuel, gassing neighbors and listening to that sweet music any longer than the engine basically needs. This has also been the norm for several of my own OS and other non-ferrous modern engines. At least they reach a usable plateau much sooner than the iron-in-steel setups, as those metals do not have the higher expansion rates that allow cutting-in designed tapered fits. For RC Carb engines, it makes more sense to set idle and transition AFTER the initial wear, as heat, handling and economy all shift as the engine approaches its break-in plateau. Mfr instructions often indicate that you should either wait until after a half-hour or hour of running time to achieve final carb settings, or at least recheck them after a similar runtime total. The flying I most enjoy is CL Precision Aerobatics, where absolute engine reliability and consistency are crucial. I still like the sound of the 4/2 break style run, but recognize that there are more of the modern engines NOT designed to do that. Several of my flying buddies try to force the newer 'greyhounds' to 'mush a dogsled...' Recent engines can be controlled more easily by operating them more like what they were designed for. For CLPA, flatter pitch props and more RPM restrain excess speed, AND fit the non-ferrous engine design package better. The older engines operated nearer torque peak - around 9000 RPM - and weren't revved to anywhere near max power. With flat pitch props, A** engines are at higher power, but mixture limited, RPM, loafing along with that power on call if needed for maneuver loads...
Posted on: 5/9/2009 8:20 PM by Author "Lou Crane" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=8755159

RE: OS 46 LA BRAND NEW LOOSE CRANKSHAFT??
FT and Bax, These OS engines are ABN ([b]A[/b]luminum piston in [b]N[/b]ickel-plated [b]B[/b]rass sleeve), so I'd go easy on using much more castor than usual RC fuels come with. There are fuels, popular in CL use, that are 10% or 11% each castor and synthetic. That, imho, should be enough castor for fairly typical RC sport use. More than that may work against the designed-in "fit at operating temperatures" manufactured into the modern engines. The parts are tapered just enough that the hot end of the stroke expands to optimal clearances when they've warmed up. That's why they pinch or squeak through top dead center when new. FT's original question has been well-covered, but I might add that BB engine shafts [i]can[/i] be fitted-up too tight. Sensitive fingers should be able to detect, by feel [b]not[/b] by eyeball, an [i]almost[/i] non-existent shaft fore-aft motion when the engines are cold. I have had a few of these that needed a gentle touch to free-up to allow crankcase expansion from running temps. Complicated thought - fuel admitted through the carb chills that part of the shaft and case, but the crankpin end IS warmed...
Posted on: 5/7/2009 1:46 PM by Author "Lou Crane" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=8748722

RE: 2 cycle oil
AJ4PJ. Another good thing I've heard about KLOTZ - I believe they also sell castor oil. Their policy, so I've heard, is to do further filtering beyond the Baker's AA standard. So, it is almost certain to be "better" than most castor labeled as Baker's AA. Whether that makes any real difference may be moot. Almost all the castor in the fuel passes through our engines as they run, leaving only a very nice rust-proof coating on the moving parts. (...and some mess on the outside of the model. Proof that it has done its job...)
Posted on: 5/7/2009 1:27 PM by Author "Lou Crane" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=8748666

RE: 2 cycle oil
RE: Anything good to say about KLOTZ? From what I've heard/seen/read, KLOTZ products are truly fine for the purposes intended. They are also more widely available than hobby shop / SIG Baker's AA Castor. Go-Kart or racing motorcycle/bike shops, etc., for example... Personal preference is to match the oil with the engine. For iron in steel (piston, cylinder. Or iron-ringed piston in steel or iron cylinder...) I still think first to use castor. For non-ferrous (that is, NOT iron or steel) metal piston/cylinder engines, manufacturers usually recommend a blend of castor and synthetic oils. Choice of oil depends on many things. The silliest reason to use synthetics, IMO, is that the oil mostly burns, thus leaves little goop on the model... For the modern precision fitted non-ferrous engines, where they are cut to dimensions that open up to optimal at operating temperatures, castor is NOT particularly suitable as the [u]only[/u] oil in the fuel blend. As it doesn't burn in the combustion, there's an effect that it physically carries heat out the exhaust. That heat may have been better used to expand the moving-parts fit to optimal. Also, castor does char somewhat when exposed to combustion heat. For porous, cast-iron pistons, charred castor embeds into the surface which 1) can take up space that might be lost to wear, and 2) acts somewhat as a lubricating film at operating temperatures and RPMs. The tapered-fit, modern non-ferrous engines do not have room for [b][u]any[/u][/b] build-up of charred castor, which might also affect heat flow into and out of the piston itself. ...forming sort of a heat barrier... Now, I'm talking more like ideal world situations. Sure, an ABC/AAC/ABN engine will run on a high percentage, castor-only fuel, and an iron-in-steel engine will run on an all-synthetic oil fuel. Much depends on initial break-in, harshness of use, and other practical factors. One friend, at least, mentions good results running the notorious Fox 35 on a typical modern RC fuel, i.e., 10% to 11% each castor and synthetic oils in the blend. An A?? engine may never reach its maximum potential if broken-in and used regularly on an all-castor fuel - without the designed heating of the piston and sleeve, there may be "excessive" wear at the top of the stroke. Honestly, how many of us run our engines at their ultimate max performance? Racers? Sure, but how many of the rest of us... The friend I mentioned and I both fly CL Precision Aerobatics, which is not a discipline that requires an engine capable of X horsepower at 18,000 RPM to run that way, ever. We spend most of our (no throttle, remember) running time nearer the engines' [i]torque peak[/i] RPM. That is - almost universally - somewhere between 9,000 and 11,000 RPM. Even 3D RC doesn't appear to require the engines to run at the mfr's stated max horsepower RPM. (The small props needed to reach that peak RPM would NOT be practical...)
Posted on: 5/6/2009 3:54 PM by Author "Lou Crane" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=8745982

RE: Did I damage my motor?
Mike, Another thing to consider is that our two cycle engines pass fuel/air mix through the lower crankcase before it transfers to the combustion chamber to burn. As you point out, ONLY metered, timed direct fuel injection will 'feed' fuel to the combustion chamber with precision. For whatever reasons, fuel/air quantity in the lower case, or the efficiency of transferring it the the combustion chamber does seem to vary in every engine I have bench-run. Probably, that applies to all in-flight conditions, but as we are further away, the sound may seem more steady. Even with metered, timed, combustion chamber injection, the air transferred 'up' might also be subject to varying over a few revolutions. That could [u]still[/u] lead to measurable RPM float. The RPM range you cite doesn't seem to me excessive. I'd agree with combatpigg - go ahead and fly it. He may be overstating the possible effect on shortening the engine's useful life, tho. Run sensibly, and barring crash damage, your engine should last a good long time...
Posted on: 5/4/2009 6:40 PM by Author "Lou Crane" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=8740573

RE: Diesel Identification D.A (Norway)
Ah, yes... The third engine in the upper row is the DA 2.5cc/.15 cu in I found in the 1950's. Wish I still had it! Life, military career, family and time got in the way. Wonderful engine! Thank you for the memory!
Posted on: 5/4/2009 6:25 PM by Author "Lou Crane" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=8740547

RE: Competition - Super 70's?
Chris, ...good point on the "how" rather than the "whether" to do it... At this point, the "how" is an approach to making it clear "whether" we do it again. If Super-70s shows good support, we also know that Classic has good support. The discussion turns to whether or not Classic and Super-70s should be fully separated events, without the either-or factor. Then the "how" question, again, but with the practical areas of staffing and field capacity being examined more closely. If it IS popular, it will get the needed support! Those who want it to succeed will help make it possible. We've been doing that for a long time: Some of the guys who'd like to fly the event often do not, agreeing, instead, to serve as officials so that the event CAN be flown.
Posted on: 4/23/2009 5:46 PM by Author "Lou Crane" in the forum "Control Lines"
http://www.rcuniverse.com/forum/fb.asp?m=8709415