Do glow heads really glow???

G'day Policetac.

What RknRusty said  . Especially the bit about castor oil. Coxes MUST have castor oil.

You can remove the glow head and watch the glow element. It should light up almost instantly.

Welcome!
Dins

I have some pretty dim glowing heads (yes, fresh batteries) that run the engine just fine. You may want to check for glow in a dimly lit or shaded place.

For checking the element with a probe, such as a pin or needle, be prepared to buy a new glow plug or head. However this can eliminate problems from a bent element, and will positively identify a bad connection. No, you can't repair a glow head that the element breaks out of.

I use 3 D-cells in parallel using 3 single battery holders from Radio Shack. Each holder is wired directly to the binding post. I got fancy and used some black plastic sheet (lexan) underneath the battery holders, and to hold the binding posts. This is screwed to a 1x4 that is trimmed neat.

This arrangement lasts a long time per set of batteries, but I take the batteries out so they are disconnected between flying days. I remove the batteries because of concerns about cross-draining, and I don't get to fly but every few weeks.

Run your engines at night for a sweet light show. You can see up the exhaust slot and see the fireball even in daylight. Often there are tongues of flame too.

Phil

08.08.2013
Must have Castor oil?
Okay, I guess I didn't read all of the posts...
Okay, Castor oil?
In the fuel? Or in the cylinder?
If it's in the fuel how come they don't just put it in there to begin with??? If it goes into the cylinder, (makes more sense to me:) then I assume it's used in order to increase the initial compression???
Some clarity on this would be greatly appreciated.

To the glow plugs.
I tested for continuity, and everywhere I touch the plug I get a "connection." I am to then assume that this is a closed "short" circuit? I'm guessing with the "coil" as the resistance?
And that this "short" is what is going to be causing the "head" to heat up and "glow."
Okay, pretty much the mechanisms I figured. Problem is though, I got two good readings, am using two "new" batteries, and have good readings as well on my wires and connections. Still no glow however. (Will I see it in regular "room" light?

Hmmm. Perhaps they are bad.

Well, I haven' started the project yet today. I wanted to check here first. So, now that I've done that, I guess I'll take your folk's help, and take another look at the things right now. I'll let you know how things turn out.
Wish me luck!
Thanks again,
Rick

These are a 2-cycle motor, so the oil is in the fuel. Cox engines are lapped mild steel pistons and cylinders so they are not as robust as more modern hard plated engines. The fuel should have minimum 18% total oil, with at least half of that being castor oil. 20%-22% total oil will improve engine life. All castor may be necessary with worn engines because the varnish buildup may be all that is sealing the piston. Castor is necessary because the piston is on a ball joint, which is a difficult to lubricate connection.

Under room lighting you may need to cup your hand over the plug to see a glow if it is dim. Outside on a clear day you will need to cup your hand even if it is a strong glow. The resistance of the glow element is very close to a short circuit. It may be less than 1 ohm. If you are using alligator clips you need to use a covered clip for the post to prevent an accidental short (or a couple wraps of electrical tape), and a large enough clip for the cylinder that it can grab the diameter.

I prefer this type of clip because it works on my bigger engines too.
http://coxengines.ca/cox-glow-plug-clip-tweezer-style.html

but I have used alligator clips and they work fine. I have also used this type
http://coxengines.ca/cox-glow-plug-clip-oem-style.html
but I like the tweezer / clothspin type to better, it's a personal choice.

Plugs can also become dirty and this will prevent them from glowing brightly (probably what is wrong with some of my glow heads). If you drip a little fuel into the energized head it will boil and smoke. This means the head is electrically good. You can attempt to clean using MAP sensor cleaner (or acid, but I have never tried this)

Phil

Well, I discovered the probable cause of my starting problems.
"Parallel" Not "In Series!"
Here's the deal though. As soon as I discovered this, I went to wire the batteries together, but before I could even get to the connecting wires on top, (positive) the one on the bottom started getting really, really hot. (or at least a good warm anyway!)

So, I've got two (2) "D" size batteries just sitting here waiting right now for me to quit acting like a baby and just "wire 'em up!" :/

It's going to be negative to negative, positive to positive, both to one lead each right?

Thanks. I'll be hanging out this time in case a chat is needed.
Again, I really appreciate all of the help.
TTYS
Rick

Castor oil is the lubricant that is in the fuel. For instance you can have fuel that is 25% nitromethane/55% Methanol/ 20% castor oil. That mix is a good old timey recipe for Cox engines.

When castor oil is heated inside the engine, it forms longer chain polymers in the form of a varnish that coats the internal parts. This varnish protects the ball socket between the piston rod and piston, and also a light varnish on the cylinder walls helps maintain compression. Without that buildup, the piston and rod WILL fail. Sometimes the varnish can build up to excessive thickness on the cylinder walls and will slow the engine, and require cleaning. This commonly happens shortly after breaking in a new engine.

When synthetic oils are heated, they flash off into their basic components... in other words, they burn off, and exit through the exhaust as plain old smoke. Used alone(with no castor in the mix), they leave behind no protective film to protect the con rod and piston socket, nor do they help maintain compression. Castor's characteristic of not burning means most of it in its original form exits through the exhaust, taking heat with it. So castor regulates the engine temperature, another important advantage. With pure synthetic, the Cox engine would quickly overheat.

In recent years synthetic oils have become common in the mix too.  Combined with castor, they wash some of the varnish off as it builds up, while still allowing a beneficial amount of varnish to remain. This is where modern synthetic oils help. This keeps a happy engine that can run for many years without having to be de-varnished. An example of this fuel would be Sig Champion 25, sold by sigmanufacturing.com (and several other suppliers too). It is composed of 25% nitromethane/55% methanol/20% oil, where the oil is a 50%/50% mix of castor and synthetic. Any oil used in a Cox engine must be composed of at least half castor. For me personally, Sig Champion is the gold Standard for Coxes. Some brands have 17-18% oil which is good enough too. I personally prefer 20% oil.The Super Power fuel has 18% oil, of which only 10% is castor, and 90% synthetic. Bad juice. They should be ashamed of themselves.

I hope this clears up some of your questions.
I just got back from 5 hours of flying, so I'm about to faceplant on my keyboard. I'll get back later as will others to help answer more of your questions.
Rusty


EDIT: Phil beat me to it. I was typing while he was posting.

policetac wrote:Well, I discovered the probable cause of my starting problems.
"Parallel" Not "In Series!"
Here's the deal though. As soon as I discovered this, I went to wire the batteries together, but before I could even get to the connecting wires on top, (positive) the one on the bottom started getting really, really hot. (or at least a good warm anyway!)

So, I've got two (2) "D" size batteries just sitting here waiting right now for me to quit acting like a baby and just "wire 'em up!"  :/

It's going to be negative to negative, positive to positive, both to one lead each right?

Thanks. I'll be hanging out this time in case a chat is needed.
Again, I really appreciate all of the help.
TTYS
Rick

Right, parallel only. Series will fry the element. 1.5 volts to light a glow plug.

Make sure your glow plug isn't full with castor goo.  If it is, a quick and easy tip is to heat it up slightly with a propane torch and it will pour out.

So is it ok that the batteries started to get hot? Or was that just because I didn't have it completely wired yet?


Using the picture that shows the batteries, this would be correct right? (If I connect them the same way as they are laying in the picture, only actually "ON" the terminals)
Thanks

Pull the plug off and see what it's doing.

Before you go any further please mount the engine to a block of hard wood and mount it in a vice or bolt it to something stationary. If and when it does start that C clamp will not hold it and you could get injured.

The batteries should not get hot. Also the wire you are using is not shielded and could short together or against something very easily.

Ron

Yes you are doing it right, but the batteries should not get hot just sitting there.  

The "cross draining" I was concerned with which is why I always take the batteries out at the end of the day, and may be why the batteries are getting hot.  If they are fresh batteries of the same brand they _should_not_ (heh) cross drain.  If one battery is at a different charge state than the other cross draining becomes possible.  

If you want fancy...
http://www.radioshack.com/product/index.jsp?productId=2062249
http://www.radioshack.com/product/index.jsp?productId=2103985&clickid=prod_cs

There's my shopping list, add in a few screws, a block of wood, and maybe a piece of plastic or a project box and it will be easy.  Using the binding posts means you can get a plunger type glow plug driver for bigger engines in full cowl airplanes with no effort.

Or order one from Bernie
http://coxengines.ca/cox-starter-battery-box-with-clip.html
or Matt
http://www.exmodelengines.com/battery-box-glow-plug-clip-for-cox-engines.html

Wrapping the battery in tape is probably easier than soldering, and is what I did before I got the battery holders.  

Heh, narrow engine
https://www.coxengineforum.com/t4224-uber-rare-narrow-babe-bee-tanks?highlight=narrow

Phil

pkrankow wrote:If you want fancy...
http://www.radioshack.com/product/index.jsp?productId=2062249

I bought a pair of those, which can be quickly change from 1.5v to 3v if needed.

Cribbs74 wrote:...The batteries should not get hot. Also the wire you are using is not shielded and could short together or against something very easily.

Ron

That wire is too thin. You need heavier gauge quality copper wire, like 14g, and seriously solid connections. That plug draws several amps.

Okay, here's what I'm going to do.
I just got back from the pharmacy with a bottle of Castor oil.
I'd like to mix a small batch of fuel, but I don't know how much to add.
The previous posts states, "25% nitromethane/55% methanol/20% oil, where the oil is a 50%/50% mix of castor and synthetic"
So my question here is: "If the oil is already added to the "Super Power Fuel," and 1/2 of it is supposed to be the "Castor" oil. then how much of the "additional" oil I just bought should I "add" to the Super Power Fuel?

Oh, and I rigged a battery/starter unit.

OK, do you remember your high school math? (yes) This is easy then.

Write a simple spreadsheet to calculate oil volume per fuel volume, then calculate the percentage after adding a portion of oil.

There are some calculators online, but I strongly recommend working it out longhand at least once so YOU know what the numbers mean.

I can email you my Excel spreadsheet if you want.

Phil

Thanks, Phil, I'm banging my head against the wall. I keep coming up with this, but I don't think it's right.

Actually it looks good, no I am not working it out longhand but I may switch to the laptop and compare to my spreadsheet.

Sig fig on the castor volume, but that is just how many decimal places you carry (0.58 would be carrying the extras in the first line).

I pull the synthetic oil volume out too, but it is just a different angle to look at.

It looks like this can't be doped with "enough" castor to hit 50/50.  

Phil
edit:
My spreadsheet produces the same values.
Phil

Cox glo heads don't glow orange as they should is oxidation on the aluminum clyinder head. Polish the suspect head with a Dremel buffing for a possible fix before replacing the head.

SuperDave

Okay,
Here's an update.
I still haven't gotten the motors to actually start yet.
I even tried straight power fuel, but I think my problem has been with my "battery/glow plug setup. (Timing/3rd hand reliance! R and D is slowly eliminating this as a problem however!

Then, I just got this stuff dropped off at my door today.


Note the one on the bottom with the yellow propeller? That one is really cool looking. I especially like the air cleaner.
I still don't know how to get around the formula problem. (Being a shade-tree quantum mechanic probably doesn't help.) I mean, I could add 1% of the Castor oil to the pre-mix, but then my nitromethane, and Methanol percentages will share in a dilution reduction as my oil percentage rises by 1%.
Perhaps I'll simply "coat" my cylinder with the oil, and use pure Power Fuel, just for starting. (I've yet to get these even running remember?
That said, anything interesting in these motors?
I'll be back later today and let you all know what happens.
Thanks for being here,
Sincerely
Rick

Rick,

The yellow propped engine is your bog standard TD .049 and the air cleaner is actually the venturi with the screen being added sometime around 1973.

These things are not to hard to start so something is up for sure. Your fuel can be as low as 10% just to fire one off, even if it's just off prime. The oil needs to be around 18-20% so if you can get that going then your fuel will work to start one.

As to your battery even one D cell will do the job in a pinch. If your glow heads are suspect take some of your new ones and try those until you can get one to glow.

Ron

Okay, cool. Thank you for the reply.
So. once it comes down to the Castor oil,k I can probably get away with simply adding a small "dollop" to the full quart of Super Fuel that I've got.
Yes, I would have to agree. There isn't much that should really go wrong with these, which leads me to believe that It is in fact "me" and my current fears of energy that have been interfering. (I've been doing a lot of strange things with low power energy lately and I'm afraid I've become a little gun shy to the amounts we think of as weak.
But, as I said, I think I've got that one licked.
I'll be back with my next post hopefully with some good news.
Thanks again
Rick