RE: Props-More Myths Busted

RE: Props-More Myths Busted
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RE: Props-More Myths Busted - 1/11/2007 2:39:08 PM

skiman762

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Joined: 12/1/2005
From: Nashville, NC, USA
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My real point is that there is no one brand of prop that is the best for all uses on all planes and all flying styles and that is a FACT
It's like saying an elephant gun is better then a rabbit gun,not if your hunting rabbits
and we don't need to be attacking each other over it.
It takes the fun out of being part of the forum at least IMO

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Post #: 151

RE: Props-More Myths Busted - 1/11/2007 3:15:16 PM

DarZeelon

Posts: 6978
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From: Rosh-Ha'Ayin, ISRAEL
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Skiman,

Don't take the arguments here too seriously.

Some of us do have right opinions about some issues and others have all the wrong opinions, about the same issues (at least this is how each of us perceives other opinions

). We trade some 'verbal punches', but we all stay happy.

This forum would have been a pretty boring place, if every time someone asked a question, he would just get one definitive, final reply. So we argue a bit, but none of us attack any of the others

.

It is just the culture of this forum and you can also join in and argue with, or against any of us...

Just take my advice and never argue with facts. Often, stated opinions do contain some of those...

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Post #: 152

RE: Props-More Myths Busted - 1/11/2007 5:02:02 PM

skiman762

Posts: 1166
Joined: 12/1/2005
From: Nashville, NC, USA
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True enough I have found myself caught up it that myself
But just think of all the great things we enjoy in this world because someone wouldn't except something as fact
I guess if it's all in fun but sometimes these post seems to exceed that
So as Dave would say
Let the MythBusting continue

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Post #: 153

RE: Props-More Myths Busted - 1/11/2007 6:05:30 PM

DarZeelon

Posts: 6978
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From: Rosh-Ha'Ayin, ISRAEL
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Skiman,

Don't confuse facts with common misconceptions....

Gravity is a fact.
'The earth is flat' was once a common misconception...

Those R/C related misconceptions are the 'myths' that some of us start new threads to bust...
Other myths are just 'busted' in various threads.

Do you still remember, in short form, the myths this specific thread was created to bust??? I don't...

Brian (downunder) tried to discredit the recommended use of a high-pitch prop for break-in.
He didn't manage to prove it is incorrect and instead he got many proofs of the inadequacy of the low-pitch for optimal cooling.

There was a common misconception that two-stroke engines must be run rich on the low end, so fuel would accumulate in the crankcase and would then 'replace' the accelerator pump that isn't there, when the throttle is 'walled' again...
I proved it is dead wrong and that any fuel accumulated in the crankcase will be detrimental to a clean transition... that our engine do very well without any type of acceleration fuel.

The low end must be a bit richer than the top end, so that the engine will have a 'virtual' ignition delay.
Less ignition advance is required at low RPM, than at high RPM. This is the sole purpose of the richer low-end.

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Post #: 154

RE: Props-More Myths Busted - 1/11/2007 7:31:48 PM

skiman762

Posts: 1166
Joined: 12/1/2005
From: Nashville, NC, USA
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Yeah I lost track of the myth being busted myself I'm sure APC was in there somewhere
I agree with the facts and misconception
On the pitch for cooling my mind tells me there's a limit to how much air is needed because the cooling process depends on how fast heat can transfer from the engine surface to the air and no amount of extra air is going to help I remember years ago don't remember the company up in the northeast somewhere that had a process that filled in all the pores of a air-cooled engine with some baked on finish and by doing so increased the surface area by almost double they
used a bunch of heat sensors on engines before and after and it really did help with cooling then they started shaving the cooling fins off to lighten the engine
it worked as they where able to remove over half of the fin weight without the engine over heating
I tried looking them up on the net but didn't have much luck that would be a fun one to play with cut down the fins on a engine have them plate it and see if it stayed cool that would be a break through in r/c engines for sure
But I did see that liquid cooled rc airplane engines are on the near horizon that should stir thing up around here

< Message edited by skiman762 -- 1/11/2007 7:33:27 PM >

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Post #: 155

RE: Props-More Myths Busted - 1/12/2007 2:00:56 AM

blw

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Joined: 3/15/2004
From: Auburn, AL, USA
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I missed that about loading up the crankcase on 2 strokes.

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Post #: 156

RE: Props-More Myths Busted - 1/12/2007 3:23:49 AM

downunder

Posts: 3169
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From: Adelaide, AUSTRALIA
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quote:

ORIGINAL: DarZeelon
Just take my advice and never argue with facts.

Ohhhhhh....so you mean that what I found when running a new ABC slobbering rich weren't actually facts? Or do you mean that only results that agree with your ideas are facts?

quote:

ORIGINAL: DarZeelon
Brian (downunder) tried to discredit the recommended use of a high-pitch prop for break-in.
He didn't manage to prove it is incorrect and instead he got many proofs of the inadequacy of the low-pitch for optimal cooling.

LOL...get your facts straight Dar. I didn't try to discredit the higher pitched prop, I tried to find out if your statement that a lower pitch wouldn't cool as well was correct. When I couldn't find any difference you shifted the goal posts by saying it didn't have the same load as the higher pitched prop.

It's funny you mentioned that business about accumulated fuel because I remember saying that many years ago either on RCU or maybe the old FliteLines. It was just a thought I'd had because it seemed logical to me as an alternative way to do what a carby in a car does when you open the throttle (enrichen the mixture to match the sudden rise in airflow).

(in reply to DarZeelon)

Post #: 157

RE: Props-More Myths Busted - 1/12/2007 6:20:03 AM

DarZeelon

Posts: 6978
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From: Rosh-Ha'Ayin, ISRAEL
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quote:

ORIGINAL: downunder

...I didn't try to discredit the higher pitched prop, I tried to find out if your statement that a lower pitch wouldn't cool as well was correct. When I couldn't find any difference you shifted the goal posts by saying it didn't have the same load as the higher pitched prop.

It's funny you mentioned that business about accumulated fuel because I remember saying that many years ago either on RCU or maybe the old FliteLines. It was just a thought I'd had because it seemed logical to me as an alternative way to do what a carby in a car does when you open the throttle (enrichen the mixture to match the sudden rise in airflow).

Brian,

In that thread you tried to prove that what all the 'big names' were saying (small diameter - high pitch prop for break-in) is a myth.

If that is not 'discrediting' this theory, then what is?

You did not prove it because of load changes.
Those that tried to accept your theory identified higher thrust as 'synonymous' with better cooling, which is completely wrong.

If instead you had the engine spin 'load clubs' and cooled it externally with a variable speed blower...

Maybe if you could (!?) 'prove' low speed air-flow cools the engine just as well as high speed air-flow...
But you know this isn't and cannot be true.

About the accumulated fuel; at a time it also seemed logical to me; and it was even stated by some 'big names' in far past issues of MAN magazine. This was a common misconception that proved to be untrue.

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Post #: 158

RE: Props-More Myths Busted - 1/12/2007 9:30:09 AM

Harry Lagman

Posts: 1144
Joined: 11/19/2003
From: Auckland, NEW ZEALAND
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quote:

ORIGINAL: DarZeelon

Brian,

In that thread you tried to prove that what all the 'big names' were saying (small diameter - high pitch prop for break-in) is a myth.

Who are these "big names"? Is this another fact some of us may not be aware of? What is the clinical definition of a "big name"?

(in reply to DarZeelon)

Post #: 159

RE: Props-More Myths Busted - 1/12/2007 10:03:06 AM

DarZeelon

Posts: 6978
Joined: 4/9/2003
From: Rosh-Ha'Ayin, ISRAEL
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quote:

ORIGINAL: Harry Lagman

Who are these "big names"? Is this another fact some of us may not be aware of? What is the clinical definition of a "big name"?

Grant,

I believe it was Brian (downunder) who coined this term...

It means people like the late George Aldrich, Harry Higley, Dave Gierke, Dub Jett and so on, who among other things, state you must use a smaller diameter prop with a relatively coarse pitch; often a larger prop with the blades shortened, to do a good, tapered-bore break-in.

...I may be a pretty big guy, but despite my over 5K posts here, I am not a big name...
Brian Hampton is closer to it...

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Post #: 160

RE: Props-More Myths Busted - 1/12/2007 10:30:47 AM

speedster 1919

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From: Martinsville, IN, USA
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I'm waiting for DAR to hook me up with some Bollys for testing. I didn't know they were all 1/2 sizes. But I can find simular load counterpart props. I am repairing the mule test plane after a trainer race encounter. I have a friend that tested for Allision engines and he stated certain paints retarded cooling of engines (namely metallics) and I have a hard time ingesting that. Since the water cooling in the blocks does the cooling and metallic paint is made up of shaved aluminum particles which transferr heat well. The only thing I would concede is that paint might insulate the outside metal a little and hamper cooling a degree or two. He has access to the WW2 engine museum.
That would make me think an OS LA and Irvines would run a little hotter. Look at all the Oldsmobile , Buick and Pontiac engines painted with metallic paint. Plus motorcycle guys say too much chrome on engines makes them run hotter. To me that would seal all metal pours with a heat transferring metal. Let the myth busting continue.

< Message edited by speedster 1919 -- 1/12/2007 11:27:32 AM >

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Post #: 161

RE: Props-More Myths Busted - 1/12/2007 10:51:14 AM

yallaair

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Joined: 1/1/2006
From: Floro, NORWAY
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The pitch does not make any big difference in liner temperature as long as the engine is running with low load. It's more important to keep the mixture rich. To say that you have to beak in the engine with high pitch is the same as you can not break in the engine in warm waether. The pitch will not do any big difference in the break in result....

BTW, ABC engines should have normal running temp during break in.

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Post #: 162

RE: Props-More Myths Busted - 1/12/2007 11:19:19 AM

DarZeelon

Posts: 6978
Joined: 4/9/2003
From: Rosh-Ha'Ayin, ISRAEL
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quote:

ORIGINAL: yallaair

The pitch does not make any big difference in liner temperature as long as the engine is running with low load. It's more important to keep the mixture rich.

Yallaair,

You apparently havn't been paying attention, nor have you read the discussed thread.

Pitch makes ALL the difference.

Keeping the mixture rich will prevent a tapered-bore engine from reaching working temperature that even you wrote is important.

It is best to have all the required information, before typing a reply, to prevent situations like this one.

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Post #: 163