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Prop balance query

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martin collins 130/09/2019 20:29:21
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Most of my model planes are pre owned, the ic ones get converted to electric but those that are already electric get a check over before flying. It amazes me that 9 times out of 10 the props on these are so far out of balance that i`m surprised the motor bearings have not given up the ghost..........

Is this i.c flyer mentality, shove a prop on as purchased, if it`s a bit out it won`t matter? Not knocking i.c flyers, just wondering if that is the reason.

Ultymate30/09/2019 20:42:28
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A bit presumptuous you buy a few second hand models and then make assumptions about "all" IC flyers (but not knocking IC flyers of course) frown

Tom Sharp 230/09/2019 20:45:48
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Wot if it's a folder?

martin collins 130/09/2019 20:57:25
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Not bought one with a folder, no not having a go at ic flyers, i have flown them in the past but a prop that is out of balance on an ic motor does not cause too much of a problem as opposed to an electric motor. So is it just carried over from that, just a thought i had.........

Denis Watkins30/09/2019 21:03:09
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I think pre owned may be the clue

They are selling the model and just throw any prop on for show

Prob balance awareness with IC flyers is up there with fuel and glow plug choice

martin collins 130/09/2019 21:04:45
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Ok, you may be onto something there, hadn`t thought of that.

Geoff Sleath30/09/2019 22:09:54
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3423 forum posts
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Most APCe props are quite well balanced from new in my experience. I tend to fit and run them then check for vibration which is easy to feel with an electric motor. With an ic engine, particularly singles, there's vibration even with a balanced prop.

Geoff

Handyman30/09/2019 22:11:01
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I am an i/c flyer and have always been so,with the odd foray into electric flying. I always check the balance on any prop that I buy,regardless. I started flying when i was 15 and I am 78 years old now. My early radio sets were single channel and were also valve sets. It was important then to have your receiver mounted to prevent vibration getting to the radio equipment. Hence the balancing of the propeller, or to be correct,the airscrew!!

Martin Harris30/09/2019 23:26:48
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Interesting point. Like many of my generation - and other generations no doubt, I was brought up on Biggles books and Capt. W.E.Johns made a point of the word propeller being an incorrect term for an airscrew.

Out of interest, I acquired a book written as an introduction to aeronautics for engineers by a relative, Arthur Fage in the early years of the century. He was a Fellow of the Royal Society and spent his working life in aeronautical research at the National Physical Laboratory in Teddington where, possibly due to his roots as an apprentice in the Royal Naval Dockyard in Portsmouth, one of his specialisms was propeller theory. My copy is the 4th edition from 1917 and in it, he explains that the correct term for an airscrew that pushes is a propeller and the name for one that pulls is a tractor - however he went on to state that the current terminology for all airscrews was "propeller".

Intrigued by this, I did a little research and discovered that the name was changed to "airscrew" during World War I by the RFC or RAF (perhaps after the book was written/printed?) and remained so until World War II, when reports such as "airscrew lost" could be erroneously trans­mitted as "aircrew lost". The name was then officially changed back to "propeller" which remains the case as far as I'm aware.

Edited By Martin Harris on 30/09/2019 23:32:13

Dickw30/09/2019 23:35:12
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Posted by Tom Sharp 2 on 30/09/2019 20:45:48:

Wot if it's a folder?

folding prop balancing.jpg

Tom Sharp 201/10/2019 00:36:11
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Posted by Martin Harris on 30/09/2019 23:26:48:

Interesting point. Like many of my generation - and other generations no doubt, I was brought up on Biggles books and Capt. W.E.Johns made a point of the word propeller being an incorrect term for an airscrew.

There are a lot of words and attitudes in the Biggles books that would be considered very inappropriate in todays climate.

Related question, did anyone read the Gimlet books?

Martin Harris01/10/2019 13:55:18
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Posted by Tom Sharp 2 on 01/10/2019 00:36:11:

There are a lot of words and attitudes in the Biggles books that would be considered very inappropriate in todays climate.

Nothing offensive about the word "airscrew" as far as I'm aware unless you have a rather mucky mind!

J D 801/10/2019 14:16:32
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1307 forum posts
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The one that gets me is " Airplane " .   Aircraft,  Aeroplane, even just Plane are fine by me but not Airplane, an Americanism?

Edited By J D 8 on 01/10/2019 14:21:05

Martin Harris01/10/2019 14:45:54
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Simon Chaddock01/10/2019 16:18:01
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I think with electric prop balance or the lack of it is just more obvious.

In general an electric motor is almost perfectly mechanically and dynamically balanced whereas a single cylinder IC simply can never be hence the necessity for 'tougher' air frame construction.

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