ZAGNUT

My Feedback: (1)

Iskandar, you sure seem to be putting a lot of time, effort and money into all this plug research lately...does any of this mean we'll be seeing a "stuka stunt plug" sometime in the future?

iskandar taib

My Feedback: (5)

Nope.. I'm doing this mainly because I now have the machine to do it and had a couple of slow days at work. I did some of this last year, but just got a big assorted batch of plugs off ebay recently. I guess talking to Al many years ago was what started it all... I might turn all this into an academic paper some day (it's not really what I do, though).

That and I'm itching to try some car plugs in my combat engines - I have a lot of them now!

Iskandar

iskandar taib

My Feedback: (5)

According to that pamphlet I posted, they did come in long and short reach. The elements fit both (they had hot and cold elements, I have the hot, I wish I had some of the cold ones to compare them with). Medium reach plugs didn't come along until OS, I think. I was not aware they used medium reach plugs when I started flying in the 1970s, I only found out a few years ago. I've always used long reach plugs in mine, no problems at all.

I suspect the Enya plugs are built just like an Arden, except the element is welded to the bottom. I only have a couple (which will probably never get used), so I'm not going to try to take one apart. If someone does, please post photos!

Iskandar

iskandar taib

My Feedback: (5)

AHAH!!!! Now I know what Merlin's "Glo-Bee Drop-Ins" are:

http://www.clubtamaran.com/Bujias.htm



They're direct replacements for Nelson's flat-coil 2-piece plugs. Not sure what advantage, if any, these are over Merlin's regular 1-piece Nelson, because he makes those with flat coils too - except he doesn't make them with the super-heavy duty element. Actually he does, but I've only seen them on Darrol Cady's website and they are not listed in Merlin's catalog. Who uses these things? F3D fliers.

Merlin's catalog:

http://merlinglowplugs.com/MGP_RETAI...t-NOV_2012.pdf

Iskandar

iskandar taib

My Feedback: (5)

Interesting patterns emerge from the glow head element analyses. In general, all plugs use platinum as the main component of the elements, alloyed with either rhodium or iridium, or both. The maximum amout of rhodium + iridium seems to be 30-35%. perhaps more than that and the elements become too hard and brittle, or the element becomes undesirable in some other way (too cold, perhaps?).

There are a very few exceptions - one is the old Fox racing plug (with tungsten), another is the old Cox 325 glowhead (around 12% ruthenium).

Japanese hot and medium plugs - i.e. OS and Enya (and also the Tower Power, which I think is OEMed by OS and is in all external aspects a A3) all use the same alloy - 30% or so rhodium, no iridium. Two other popular formulae for hot and medium sport plugs seem to be 10-20% rhodium (almost all the Ohlsson-made plugs, the GloBee 1L, the Norvel Freedom XL) or 20% iridium (Soviet and CS plugs, Fox plugs, the hotter Rossi plugs). Cheap plugs (like those N3 "3 stroke" plugs I bought off ebay - these sometimes go under the "HSP" name) have about 10% rhodium, the more expensive plugs have more. When used, iridium always seems to be around 20%, with a couple of exceptions. The only plug with 25% iridium that I found was these Chinese "5I" idlebar plugs - Indy RC was selling these off cheap from a jar on the front counter - a double pack for a buck. I asked him what was wrong with them - apparently they were too cold for RC fliers, engines would die if you tried to idle them. Worked OK in my Fast Combat engines with Missile Mist. Pretty much ALL italian plugs contain iridium, usually 20% or so.

Which brings me to the most popular alloy of all, which is used in pretty much all the racing plugs - 10% rhodium plus 20% iridium. This includes an overwhelming percentage of car plugs, the colder Rossi plugs (and all their turbos), ALL O'Donnell plugs, the cooler Fireball plugs, the well-regarded McCoy MC-9 (boat and ducted fan people consumed these in huge amounts, probably still do, though there are few of the latter still around).

So in essence - the warmer plugs contain rhodium (sometimes a lot of it), the colder plugs almost always contain iridium. The coldest competition plugs use 10% rhodium + 20% iridium. My guess is the iridium makes elements a LOT tougher, but it also makes the elements somewhat colder (probably not as active a catalyst as rhodium or platinum).

Exceptions? Yup.. I once said that no one uses pure platinum, since it was too soft. I was wrong - there are a very few. One is the Fireball Hot (red) plug. The other one was a REAL surprise - the Globee 4S and 4L plugs. These were one of the premium plugs used by pylon racers with 70% nitro fuel. And the Super Tigre Speed plug uses 10% rhodium with no iridium.

One brand of plugs that bucks the above trend is these IMEX plugs I got off ebay. They sell two types, the "hot" L7 and "warm" L8. The guy who was selling these would set up 40-50 separate auctions (he'd put in all sorts of brand names in the description - OS, Traxxas, Novarossi, etc. for benefit of the search engines), each for ONE plug, the starting price would be something like 90 cents. I'd wait until the auction was almost over, then I'd hit all the auctions with zero bids and bid maybe $1.20. I avoided everything where there was already a bid, this kept the price down, and was unchallenged on the bulk of the ones where I did have a bid. So I got a bunch of plugs for maybe a buck apiece! He'd zing you with $25 shipping, though, but the final price was still less than $2 a plug! Anyhoo... it turns out the L7 (the hot one) has 20% iridium, the L8 (the colder one) has 12% rhodium. How do they run? Don't know yet. The plugs look well-made - nice, thick concentric elements.

Plug finishes are another interesting aspect of this - Rossi, for instance, seems to like black oxide, O'Donnell plugs are all nickel plated. Some plugs have a natural steel finish, CS plugs show some copper (probably part of the coating). Supposedly the plug finish (which would include the cavity) influences the heat rating for the plug - a black suface would result in a colder plug.

Now comes the tedious work. Measuring all the plug cavities, element coil diameters and element wire diameters.

Iskandar

ZAGNUT

My Feedback: (1)

are these standard alloys with some kind of use outside the glow engine world?

iskandar taib

My Feedback: (5)

I think so. I do know you can get similar alloys from companies that sell thermocouples. Some of these manufacturers do make lots and lots of plugs, so perhaps they can get someone to make wire for them, others probably buy stuff off the shelf. I suspect OS"s 30% rhodium elements were blended for them, since the Europeans, Americans and Chinese don't use that particular alloy.

Then you have people like Model Technics (in Britain). Their promotional material (which I can't seem to find at the moment) made me think they had alloys custom made for them, a different alloy for each plug. Their 4-cycle plug boasts a "super-catalytic element". Problem is I don't have any to analyze - none showed up on ebay at a reasonable price.

The other data I don't have is whether the alloy use for any particular plug has changed over time. This might be for good reason - perhaps testing showing that another alloy was better - or perhaps simply because a batch of wire of a certain alloy became available cheap all of a sudden, or they ran out of a certain kind of wire and had another kind on hand.. I suspect small manufacturers (IMEX?) would be more prone to this sort of thing.

I suppose I could analyze a bunch of plugs of the same type made at different times, but I don't want to go in that direction - opens up another can of worms.

Iskandar

Sport_Pilot

Do you have a spectrum analyser or something? Have you checked out the Enya plugs?

Does the OS #8 and A3 have the same alloy? I thought they advertized that the #8 had more platinum or some such. Could have been a certain magazine writer who I know was full of it.

iskandar taib

My Feedback: (5)

Heh heh heh...



Iskandar

iskandar taib

My Feedback: (5)

Yup, the OS 8 and A3 use the same alloy. So does the Enya 3. Mind you, if any of these plugs is using some secret ingrediuent in small amounts (<1%), I won't be able to see it. I seriously doubt they are, though.

The business ends of the A3 and 8:



Also for comparison, the Enya 3 and the Tower Power:



Compare with the OS 5 (cold plug):



Iskandar

GallopingGhostler

Enya 3 and the Tower Power images didn't come out, Iskandar. I've tried to display Tower Hobbies images (if that is who Tower Power is with), they do something with their web page coding to prevent redisplaying the links in another or other session. You possibly might have to download the images and post them as attachments.

iskandar taib

My Feedback: (5)

Shows up OK here. If you see the box with the red X in it, right click and select "Show Picture".

Iskandar

sebo

I haven't read all that is written in this thread but I have been using theFOX miricle plug in 2 stroke and 4 stroke engines since the 1980's,
They were cheap then compared to now....I still have 2 full cards of them........yes, they still work well when I need a new one......One plug lasts several seasons but I only flyonce a week.
I do live inflorida so that means about 50 trips to the field ayear.

iskandar taib

My Feedback: (5)

Yeah, you wonder why there's such a huge variety of the things when one or two types "work all the time". And I think they do, too - until you get into specific types of competition, or niches (I suppose you could call cars a niche, powerboats would be another). These days I use Nelson plugs almost exclusively in engines that rev close to 30,000 RPM, and they seem to last forever. Back when I was running Fox Mark IVs, though, you'd change the plug every match - the used ones went into the "practice" box. Just in case.

Still, to me it's a fascinating subject - a lot of stuff about these things is really fuzzy - such as how exactly do car plugs and airplane plugs differ? Can you actually measure the heat rating of a plug and compare it to another plug from a different brand?

In any case... just to show you can't trust what you read, sometimes:





So where's the iridium?????

Iskandar

ZAGNUT

My Feedback: (1)

each time i refresh the page i get different photos....if i quote your post i can see the links to all the photos. could be RCU, could be your image host...or maybe they just aren't playing nice together.

iskandar taib

My Feedback: (5)

The image host is my home PC, I'll check it when I go home tonight. I suspect it might be overloaded, I posted a link on a browsable directory earlier - when that happens Google catches on and starts downloading EVERYTHING it can browse, even unedited photos which are very big. I then have to make the directory unbrowsable for a few days. Using "Show Picture" usually works for the ones that don't display.

Iskandar

1QwkSport2.5r

I have RC cars myself, 2 - .20 smallblocks and 2 big blocks, .26 and .28. I run 20% nitro 12% oil (50/50 cas/syn) and a McCoy MC59 glow plug in all of them. Terrific idle and good top end. I think the MC59 is an "airplane" plug but I've used Traxxas, OS, K&B, SuperTigre, Dynamite, and many others. The McCoys have been stellar. I use the same plugs in my aero engines with the Enya 60-4C getting an Enya #3 plug. The 4-stroke really liked Fox idle bar plugs, runs as good on those as the Enya 3 and McCoy MC4C. The OS F didn't give as good idle quality as the other plugs.

Same plug for 5% nitro as 25% nitro. No preignition or detonation whatsoever.

Edit: the little .20's are in 2wd 1/10th scale stadium trucks, the other two are in 4wd 1/8th scale monster trucks (13lb trucks). "Car" plugs seemed to have finer elements and didn't seem to last as long.

GallopingGhostler

Iskandar, I did a refresh in Fire Fox. The OS 8 and A3 no longer shows, only the OS5 shows. Refresh again, The OS8 and A3 shows, no OS5. Tower Power and Enya 3 didn't show on any instance.

iskandar taib

My Feedback: (5)

I think I've fixed it. There was a setting in the server that allowed only 3 simultaneous connections per IP address, I've increased it. If THAT doesn't work, try the right click -> Show Picture thing.

In any case.. here's a photo of several OS plugs in a row. Right to left (it WAS left to right on the scanner platen!): A3. Tower Power, BE3, 8, 5, P7. Note that the BE3 has a teeny bit more reach, diameter is smaller, some sort of metric thread.



Iskandar

Sport_Pilot

Well then I suppose the fact that A3's don't last as long for me is that either they are usually hotter than I need, or a thinner coil. Enya 3's seemed to last longer. Or maybe just the luck of the draw.

qazimoto

My Feedback: (1)

The BE3 thread looks rather course, maybe a standard M6?

What's it's application? Do OS sell a special optimized Ethanol glow engine?

If so what's the point? I'd expect that Methanol is easier and cheaper to make that Ethanol anyway, and it couldn't be significantly "dirtier" in terms of GHG emissions.

Ray

fiery

My Feedback: (2)

That's it Ray. It's all about the sizzle, not the steak.

The special OS lubricant stongly recommends for the BE engine is eco friendly and bio-degradeable! An amazing beakthrough! No doubt manufactured from that a magical scource ricinus communis .

[:@]

GallopingGhostler

Is OS actually going to ethanol based glow fuel, or is it going to gasoline containing ethanol content with a special plug that catalyzes gasoline to fire like a glow engine?

iskandar taib

My Feedback: (5)

The "BE" stands for "Bio-Ethanol". I think they actually sell pre-mixed fuel, not oil. No nitro, if I recall. Special BE engine, too (there was a .55 last I checked, may be more now). The schtick, as they say, is that the ethanol is not derived from fossil fuels, unlike methanol, and is therefore environmentally friendlier. Before anyone goes off on a rant about this, remember, it's a schtick. I think it's interesting, no more, and withold opinion on its merits.

I suppose this WOULD make sense in, say, Brazil, where supposedly you can buy ethanol for cars at the pump.

I'll betcha they are working on a glow-gasoline engine, too - everyone probably is.

Iskandar

downunder

Isky, it seems the backing uses a 1mm grid and going by that it looks like the P7 turbo plug has an 8x.8mm thread (which I believe is correct) while the BE3 seems to be a 6x1mm thread. The rest of course are 1/4x32.