gcb

Harry, what type of flying do you do that you can run the engines that rich?

I fully agree that if you can keep the temps down, synthetic does a wonderful job of lubricating and running clean. It's those times when you run them hard and sometimes tweak the needle a little too lean that castor comes into play. It's when the synthetic flashes off and does not lubricate that the castor forms that black gunge that you speak of. This is especially important in iron/steel combinations like the Fox that are subject to thermal runaway. I assure you that the baked-on castor on an engine's head does not occur at temperatures that you can touch.

I would guess that if everyone was so careful about setting the needle, it would not matter much what lube you use.

Also, that characteristic about filling scratches, etc. is why castor forms a varnish on iron pistons and increases compression when the engines wear excessively from use. Fox Superfuel (28% castor) at one time advertised extending life to worn-out engines (iron/steel days).

I like at least half of my lube to be castor, and a total lube of at least 20% for engines under .40ci. size. Just a personal preference.

BTW, I was in Vienna last year to visit daughter and family...beautiful city.

George

lukesp

Very interesting post Harry, considering it was your first on RCU. A veritable throwing down of the gauntlet to those dreadful castor users.

Let's see, So, you have vintage diesels and sparkies as well as glow engines and you FLY ALL of them on a regular basis? Please don't tell me your theory on oils is based on bench run only. It's an easily controlled enviroment compared to actually flying all of those going back to the forties and beyond vintage spotless engines you have.

Good for you, but this means that you are a remarkably succesful collector more than anything.


Castor oil does not burn engines, moronic operation does. I have an Enya 45, OS35S and two Enya 35s to prove this. No, I didn't ruin them, two are from a friend who swore by synthetic oil and basically roasted both engines in flight, the other two are Ebay finds and there is absolutely no trace of castor varnish on them, even though the wrist pins, rod little ends and pistons are flogged out. I guess they used all synthetic. The Enya 45 has a spun big end (i.e. a ruined conrod) and also not one trace of castor oil to it. The big end is definitely burnt though.

I prefer to use castor oil and sometimes use a 50/50 blend of oils, but the one thing I don't do is belittle the choice of others. If you want to use synthetic oil then by all means feel free to use it. I also have a LARGE collection of engines and I do NOT use synthetic in them. These engines do NOT notice the fact I am using stone age oil in them.

Harry Lime

How did you guess that I was from Vienna with a name (me) like Harry Lime! I know my parents are avid film and movie enthusiasts and their favourite past-time is using Ferris Wheels. Mine is model aeroplanes and as to engines, I have been actively flying the Fox 35 Stunt and the big ringed 60 Hawk and Eagle for 20 or so years using green Morgan CoolPower 5% ever since it was available. I can't remember who told me to always feel the temperature of the cylinder head while tuning (NOT peaking - get yourself a bigger engine size up) the engine just before flight, but we all do so in my club. You can tell what club we belong to when you shake hands and feel those strange burnt-in grooves in our fingertips!

Harry Lime.

MOLE21401

My Feedback: (2)

I ordered some old style high castor directly from Fox 2 months ago....got it in qt.s

cutaway

Sig sells Castor too. Klotz has Benol, which is basically red tinted castor, but they want a lot of money for it.

Lou Crane

Interesting, Harry...

However, there are a few simple things that encourage most of us to use oil suited to the purpose - a different purpose than yours, perhaps?

Our engines are "heat" engines. Power comes from the expansion of the products of combustion. Cool running may be just dandy for the lifespan of an engine, but if its purpose is to produce power, we need to work with a suitable amount of heating...

About 35 years ago, Dave Gierke published a series of articles in Flying Models magazine that dealt with many valuable things. Among which, and a quick scan of the articles didn't find the specifics, was the flash point temperature of the oils we use. Castor survived at head temps that burned away all synthetics (then available). I doubt that, for our uses, many - if any - synthetics have improved significantly in this specific since then...

So, if we want power from a delta-heat, the greater the difference between fuel/air mix before burning and after, the more power we can translate to the shaft, the prop, and the model. That can quickly put us in the range where a 'finger check' on upper/outer cylinder temperature is not in the realm of possibility. In THAT case, an oil which does not burn away during combustion makes sense. (Given: after combustion, residual oil only meets the bare metal of cylinder walls, a coating refreshed as the new charge 'goes upstairs' to be burnt.)

As to how prehistoric which oil is: Castor is pressed from this year's crop. Petroleum-based oils are extracts of dinosaurs, ferns and other living organisms not seen on our planet for dozens of millions of years. Synthetics are laboratory experimental products trying to emulate the petroleum-based lubricants. So, which is most modern? (And, is this a question the "renewable-energy" types DON'T want asked? - How can this year's crop of wind, tide, leaf, etc, be a valid substitute for the distillate of hundreds of millions of years of the natural processes which make petrroleum available to us?)

Sure, even castor-dependent engines such as the Stunt Fox 35 can survive on other oil regimens -IF the mode of operation is sufficiently compromised to keep temperatures

gcb

That's an easy one. You signed your previous post, "Harry Lime, Vienna.".

Two things I missed while in Vienna, That HUGE ferris wheel, and the Vienna Opera House. Perhaps next time.

BTW, the Castor vs Synthetic is probably a discussion that will never be settled.

George

Harry Lime

Dear George,
OK, here it is: The year was 1949, the movie was 'The Third Man', the star was Orson Welles playing the villian Harry Lime, music played on the zither by Anton Karas. Recently voted by all member of the BFI as the Best Film Ever Mada!

As to castor oil. Has there been any recent tests of it versus recent synthetics? No, because the results would explode another model aero myth about the superiority of castor. Sorry about that folks. On a visit to Monza I don't recall the Formula One cars' exhausts having that heady smell of castor oil. They use synthetic for a good reason. Their piston sizes are the same as some model aero engines reving at 13,000 plus. Why do they not bother with the magic castor bean? Because it is a fairy tale, thats why.

Harry Lime.

scott17

All I know for certain is that if you are running a Fox 35 on CoolPower, it ain't running right! The castor does more than lubricate, it carries heat out of the engine also. For your theory to have any creedance, please tell about ,say, the Fox 35 in particular. What prop? What RPM? What are you flying it in? Very curious as to how you achieve said good results......

build light

Scott, you are so right about the castor carring heat out of the engines. A very important point indeed.
However, the way you make it sound as if you are making a comparison to the synhtetic oils meaning that castor does carry heat out and synthetic does not... In fact the synthetic most certainly would carry heat out of the engine. So long as the oil comes out of the engine. For that matter everything that doesn't burn in the engine and is carried out by the exhaust will carry heat with it. bubble gum, potato salad, liquid soap, gasses so lond as it doesn't burn and has the ability to absorb the heat energy, will take heat out of the engine.

OK, time to stop my silliness. As for the ability of castor and synthetic oil to absorb and hold heat energy, I have no clue as to which is more efficiant nor have I seen any test for this. for now I will assume that they are not far apart in this ability.

As for Formula One engines I am no expert by any stretch of the imagination but one thing is for sure:
Typical F One engines are not designed to lose unburnt oil to help in their cooling. Typical F One engines use radiators and probably (remember I am not an expert) oil coolers to help maintain acceptable levels of cooling,

Another thing:
If an F One engine were to lose oil out of its exhaust at the rate compared to a model aero engine (which are two stroke engines which have no oil pan and thus rely on the oil to help cool the engine) the car would likely be impounded and banned from racing.

Another:
Are typical F one engines 2 stroke or four stroke? I think the typical F One automobile engine ( you did say "Formula One cars") are four stroke. This means that even if the F One engine were turning 20,000 RPMs it would ony be firing half the time, or 10,000 times a minute. Not a good comparison from where I sit.

Another:
Aren't the typical F One cars funded with lots of money? I think yes. Quote from Wikipedia:
"Ferrari spends hundreds of millions of pounds a year developing their car"
I don't think one could say this about our typical model aero engines.

I think that comparing these highly specialized engines using special alloys and materials to our lowly, off the shelf model aero engines Is, well, not a great choice.

I will stand and take my punishment for any errors or wrongful assumptions I have made here.

I do believe in castor oil and its use in model aero engines but I do not think it is the only oil that can be used. Use what you want, I will stick to castor or at least a percentage of castor in my fuel. I lke it.

Robert

Brokenprop

My Feedback: (6)

So, the hot castor goo carrying the thrust producing heat from the engine lubricates the unbushed bellcrank in the Brodak ARF's and if you use synthetic, the covering on the flimsy construction will fall off? Did I get that right?

cutaway

I notice a very distinct handling difference between a 5/29 all castor SuperFuel clone I mix myself and a gallon of 10% Omega with an added pint of Castor. Both run OK, but the mutant Omega doesn't do a crisp 2/4 break as readily as the 5/29

That's with old style mehanite/steel P/L. I don't have any of the newer ABC or Ceramics to play with.

gcb

Well, if you're going to bring up Formula one cars, etc. I live about ten miles from "Old Rhinebeck Aerodrome" and AFAIK they still run the old birds that have radial engines on castor. ...and they keep going, and going, and going...

Is it fair to classigy a synthetic that is partly composed of castor as a synthetic? Perhaps it is just modified castor. [&o]

Part of the answer may lie in what is a cost effective product. Cheap synthetics are not as good as castor (in model engines). Perhaps expensive synthetics are better for our purposes, but not cost effective in the USA. Many people HERE prefer the cleanliness of synthetics and the protection of castor so use a blend of both. How much of each depends on metallurgy of the particular engine. Those who fly iron/steel seem to prefer mostly castor, while those who fly ABC, AAC, ABN, etc. often prefer mostly synthetic. And, of course, these are not absolutes, only rememberences from many comments read on various threads over the years, coupled with my own experiences.

Sorry, didn't mean to ramble on.

George

I understand that as little as 3% synthetic will clean the varnish seal off an old iron piston.