Diesel Engines

Set the needle (turn and a half) as you would a glow, then turn the compression until it feels a little tight when you flick the prop. Give it a flick... IF it starts... adjust the compression until it sounds right. If it doesn't start, increase the compression a 1/4 turn and try again.. repeat, lather, rinse... then fiddle about with both adjustments (needle + compression)... You will get the hang of it... Diesels are one of those things you do 'by feel' there are no set guidelines... As for fuel.. 1/2 castor oil 1/2 pure ethanol and a dash of nitro works for me.

Regards

Thomas

Hi Thomas, Getting a model diesel started with no ether borders on the miraculous but what do I know since I have only had two diesels and they were prehistoric ;-0 However, I'd suggest the following mixture; Kerosene - 42% Ether - 32% Castor Oil - 24% Iso-propyl Nitrate - 2%

Why risk blowing yourself up fooling around with ether when you can buy the stuff?

Check this out for the straight skinny -

I used to love running model diesels. I still have my OK Cub .049 Diesel and my McCoy .09 Diesel from the late fifties/early sixties. I used them on control line models. No, wait. I never flew the OK Cub .049, but I did bench run it.

I managed to finish the summer of 62 flying the McCoy .09 Diesel. It replaced a Fox .15 that was doing duty on my Scientific Stuntmaster, IIRC. Couldn't afford the glow fuel and the Diesel was given to me along with a quart of Diesel fuel. Testors, IIRC.

Anyway, I revisited model Diesels in 1992 or so. I installed a Davis Diesel Conversion Head on an OS .32 S-H engine. It was installed on my Florio Stunt Wagon R/C model. I actually smelled the UPS guy walking up the driveway to deliver the Davis Diesel fuel concentrate before he rang the doorbell! I can't handle the smell in my older years. But it was fun playing. The Stunt Wagon powered by the Dieselized .32 was neat. It was nearly silent. You could hear the air moving over the model easier than you could hear the engine. I ended up flying it with a 12x6 prop. I think I could have gone larger, to be honest with you.

I sure wish someone would come out with an odorless fuel for model Diesel engines.

Ed Cregger

Tom,

the standard mix is 1/3 auto/car oil (NOT castor ), 1/3 parafin ( kerosin) and 1/3 ether ( di-ethyl from chemists/ pharmacy). Castor will work but leaves gummy burnt residue - car oil burns cleaner

you can buy ready mixed from model shops which I would suggest you do as the Mills is frugal on fuel and a pint/quart can will last a long time once you get the hang of it. The original Mills was a very easy engine to handle and I think the Indian replica had a similar reputation. You need to prime the engine by either a small squirt in the port or choke (finger blocking carb ) while flicking a couple of times. watch you dont flood and hydraulic lock.

you will like the sound of the diesel and the lack of glow batteries etc - but the smell of the fuel is stronger so you will have to wrap up well if taking model in house. However on the plus side the smell of burnt fuel when flying will be heaven to any old-timers flying in your locality

prop size if I recall correctly was 7x4 alltho' with the long stroke it might have handled 8x4 - maybe somebody else in group can confirm prop

best wishes with it

John

You will get the hang of it...

Sorry I meant ether Not ethanol...

Are you sure of that mix? What burns?

Usual mixes are 1/3 castor, 1/3 kerosese and 1/3 ether.

Paul,

the ether ignites , the kerosene burns as the fuel and the oil lubricates

an alternative to kerosene diesel fuel used in transport

you can reduce the oil slightly but it is not worth it. as in the glow engine the oil serves to lubricate and cool and substantial amount of it gets exhausted

a query to SAM group should confirm this

john

That is the old standard mix for plain bearing engines.

A little amyl nitrate is good, if you have it.

Ed Cregger

Some folks replaced the kerosene with scented lamp oil. I'll bet that made a few fellows scratch their heads at the field.

Ed Cregger

Why? Same stuff just smells better. What's not to like? I've a TeeDee and the diesel conversion for it so am furiously taking notes on manufacturing fuel. But IF I were to make a gallon of fuel that would last what? 5 years of flying, if you fly all day sat/sun every weekend. 8^)

John,

I was referring to the earlier post that listed their fuel ingredients as

Yes, the smell is what I was referring to and making the other guys scratch their heads in wonderment.

Once, when I was flying my Scientific Stuntmaster with a Fox .15 glow, I ran out of fuel and fuel money (summer of 1962). A friend had given me a McCoy .09 diesel and a quart of diesel fuel. I swapped the McCoy .09 in place of the Fox and began to learn how to start a Diesel model engine. No instructions, of course. I neglected to change the 2 ounce fuel tank out for something smaller. You can't imagine how tired I was after what seemed like a half an hour or more of flying on one tank of fuel.

Ed Cregger

Even goes in the fuel as well;-)

Re making large quantities of diesel fuel - totally unnecessary for engines size of the mills ( 0.75cc or 0.049 )

the ether evaporates very fast from containers so I would recommend making up no more than a pint at a time

while castor oil has better lubrication properties for our small engines , castor was always necessary for glo plug fuel as it would mix with methanol. Auto engine oil mixes OK with the ether/parafin ( kerosene ) mix and was /is standard oil for diesels and as I said earlier much cleaner both on the engine and residue on plane. commercial fuels a long time ago also used to add a shot of redex which is an auto engine upper cylinder lubricant and was supposed to assist in keeping the combustion chamber cleaner. (the auto enthusiasts among you will know about the decoking method of dribbling in redex while your auto engine is running !!)

John

We used to do the same thing using "water", believe it or not. The water flashed to steam and allegedly knocked the carbon formations loose. There was an abundance of engine mythology floating about in those days (fifties/sixties). The good part was that water was free and it never seemed to hurt anything.

Ed Cregger

Ed, Funny you should mention Davis Diesel.... I spent about $300 on stuff from Davis Diesel, for heads, fuel line and concentrate about 15 or so years ago. I messed with that stuff for days and never got so much as a single "pop" from the three engines I tried it on (2 Royal .28's and a .45). It was very frustrating and I finally gave up on the project. The stuff is still sitting in a box in the garage somewhere, although the concentrate ate it's way through the can and leaked out a few years ago.

The biggest problem was Davis. After trying all kinds of different mixture ratios with the concentrate he sent me, I finally asked for help - and got a set of instructions, like maybe I couldn't read or something. Even after repeated requests, the idiot just kept sending me copies of his instructions. He never once actually answered a direct question (all by snail mail back then) or said a word about anything and then refused to accept the stuff back because I didn't have "return authorization" which he then refused to give me! I never asked the guy for my money back, I just wanted him to try the heads and make sure they actually worked! I finally asked for a refund (several times) but he just ignored those completely.

I suspect that the concentrate I got from him was no good and I never bothered to try any other formulas, I was so ticked off about it. I may do that now, one of these days when I get some spare time, but the total lack of help from Davis soured me on that project at the time. I'm not the only one that got that same kind of treatment from him. In fact, R/C Report had so much trouble with him they stopped carrying his adverts. There were a couple of other guys at the field I flew out of that went through the same stuff with him as I did... I wish I'd of met them before I ordered the stuff. I'm not sure if the clown is still in business, but if he is, I would certainly recommend people go elsewhere if they're interested in diesel conversions. Cheers, jc

Bob is kind of "unique". If you get him on the phone you just about can't get off. He likes to talk.

I suspect that you are right about the concentrate losing its punch (ether).

If you can feel an increase in compression when you tighten up the head screw, chances are the heads are okay.

Contact FHS Supply and have them ship you a bit of fuel that is formulated to work with the Davis Diesel Conversion heads. Bob doesn't use as much compression in his conversions as normal model diesel engines. My theory is that this was done intentionally to prevent broken crankpins on converted glow engines. Hence, his fuel, and any fuel for converted engines using his conversion heads, will have quite a bit more ether than normal model diesel fuel.

It took me quite a while to get my OS set up and running properly. The conversions, especially in cold weather, are rather finicky in that their running zone (adjustment aggregate) is rather narrow. Once found, however, the engines run just fine, after a rather lengthy warm up period.

The fuel smell bothered me so much that I only messed with mine for a month or so. Over the years, I have grown sensitive to fumes of just about any sort.

The converted OS did not run as well as my previous "designed to be diesel" model engines, but it was usable. It didn't take long to recall how to adjust it once it got going.

Don't forget to back off the compression once it is running. Just a little bit until the "pfffffft" thrumming sound disappears. Save the mixture adjustments until the engine warms up and quits loping. Good luck and have fun.

Ed Cregger

Isopropyl nitrate is a suitable alternative to amyl nitrate and, possibly cheaper.

If anyone is really interested, I have a recipe for etherless diesel fuels gleaned from an article in Aeromodeller many years ago. The fuel uses kerosene (80%), "modified" rape seed oil (20%) with the addition of 2 to 5% IPN. This fuel seems to give more power than standard ether based fuels but takes more starting and the exhaust residue is very black. It also needs a slightly higher compression setting.

Malcolm

Rather than diesel conversions, why not chose an engine designed as a diesel.

Over here in the UK, PAW manufacture diesels from .049 up to .60. There are other manufacturers doing replicas of other makes and some own designs.

It could be though that they'd be a bit pricey shipped to the U.S.

Malcolm