The 2011 Special Issue

[Shane Sunday]

Mine arrived yesterday and was waiting on the side table when I got home from work. A fantastic issue! Tony has designed a beautiful aircraft no matter what the 20 year old living with us says. Kids huh? been waiting for this for months and so glad to have it. Lots of great articles that are very informative. I might be tempted to put the IC engine back in my trainer. Never tried IC but who knows now.

 

Thanks guys.

[FlyinBrian]

Still not got mine

 

A poor show - what

[Bob Cotsford]

Good article on noise from Andy Ellison!

[Biggles' Elder Brother - Moderator]

Mine arrived today while I was out flying! Bedtime reading!

 

BEB

[Steve W-O]

Mine arrived last week, the plan is very good!

 

When I opened it, I saw two errors on facing pages, one the wingspan in the full size Courier description was given as that of the model, and right opposite it the wrong abbreviation for required was used, in fact the abbreviation for received was used, which is a major mislead.

 

Apart from looking at the 190 plans, haven't had time to sit down and read the rest yet.

[Terry Walters]

Just got back from a week away and had the mag waiting for me - lovely! SWMBO has said that if I empty the camping car, fetch the croissants and a baguette - get her breakfast ready I can actually read it!! How's that for reasonable?

 

Looks a good read - well done to all concerned!

 

Terry

[Seamus O'Leprosy]

Terry, suggest you read the article sub headed " new balls please" first.

[Mark Lubbock]

Smashing issue, great plan for the FW190. I am also loving the Aces High dogfight double-nice to see a balsa version as well as the now very poular Depron construction-can't help thinking the balsa built one looks so much better?

[DENNY]

All that grumbling about how long you have to wait for the magazine.

Just think what it is like on this side of the ocean.

Hope it comes today, as it is supposed to rain all day.

[Erfolg]

There are two articles which I particularly liked.

 

The first by BEB, with respect to stability, is a very good explanation, presented clearly. I am pleased he avoided using the Aerodynamic Centre, in favour of the CP. Although the CP is a notional point, which moves with angle of attack. It is far more useful than the AC, which is convenient for calculations by engineers, having little place in modelling.

 

I am hoping that this is one of a series of articles. One which visits the apparent behavior of models, respective to the ground controller. It seems to slip most peoples notice, that models are in a moving body of air, relative to the modeller and his actions are guided primarily by generally viewing the air as static.The implications of this are often totally ignored, when discussing what has been observed.

I think that Timbo has pulled together a number of strands of information into a cohesive body of work, with respect to Brushless Motors. There is scope for further articles on the effects on pole/magnet numbers, armature diameters, armature length to dia ratios, the impact of motor turns etc. I am looking forward to those.

[Biggles' Elder Brother - Moderator]

Thanks for the comments and observations Ken and Erfolg.

 

Erfolg you're right. I have no doubt that there will be those who will take me to task for using the CP (or Centre of Lift) rather than the theoretically more correct "neutral point" - I'm just waiting for the emails! - but like you I believe that centre of lift has a much more "real" and tangible meaning to a modeller.

 

In the final analysis of course the main thrust of the argument, i.e. the effect on stability, is exactly the same whichever you use. However, the use of the NP is not only more abstract, but also complicates things by introducing a whole lot of other effects not relavant to this argument. What I wanted to do was help folks understand, in stratight forward terms, why their models are so damn uncontrollable when they get the CoG is too far back - for that CP is much easier to use and clearer.

 

BEB

[Martin Harris - Moderator]

Posted by Biggles' Elder Brother - Moderator on 27/09/2011 19:57:35:

Thanks for the comments and observations Ken and Erfolg.

 

 

BEB

Aaaaarghhh!!!!

 

It's only just clicked....

 

I knew your name was David.

I knew your job was lecturing at a university

I just didn't realise that you were the legendary Prof. Burton!

[Biggles' Elder Brother - Moderator]

Yes, my cover is blown! I'll have to contact George Smiley and see if he can offer me a job back at base!

 

BEB

 

I blame young Ashers and photos in the mag!

[David Ashby - Moderator]

Oh dear, we'll have to be nice to BEB now

 

 

 

 

Edited By David Ashby - RCME Administrator on 28/09/2011 09:12:42

[Lee Smalley]

no we don't he is a heathen !!!! 

Edited By Lee Smalley on 28/09/2011 11:31:21

[Slopetrashuk]

You can ALWAYS tell a teacher. You just can't tell 'em much!

[Seamus O'Leprosy]

and dont forget

Those who do, do

Those who can't, teach!

Thats six slaps of the leather for Seamus.

[Brian Lambert]

Is that the same David Burton who has his photo' in Model Engineers Workshop magazine?

[Malcolm Fisher]

Seamus, you missed out the last line -

 

"Those who can't teach, teach the teachers..."

 

Malcolm

 

Edited By Malcolm Fisher on 28/09/2011 19:31:26

[Seamus O'Leprosy]

Malcolm

That was on purpose.

Six slats of the leather is all I could take

 

[Biggles' Elder Brother - Moderator]

Posted by Brian Lambert on 28/09/2011 18:54:59:
Is that the same David Burton who has his photo' in Model Engineers Workshop magazine?

 

Not as far as I know Brian! Unless David A has been doing a bit moonlighting!

 

Just for the record I do very little actual lecturing these days - I teach on one module, on a Masters degree - 12 hours per year max. My main job is running a large research team undertaking contract research projects in fluid mechanics, machine vision and laser based measurement and machining systems - sorry to dissapoint you chaps!

 

BEB

Edited By Biggles' Elder Brother - Moderator on 28/09/2011 20:27:27

[Seamus O'Leprosy]

Fluid mechanics eh. how about a study on how quick I can drink this pint of Guinness

[Biggles' Elder Brother - Moderator]

Faster than I can calculate it I would estimate Seamus

 

BEB

[Steve Hargreaves - Moderator]

I just wanted to add my congratulations to BEB also...the article on stability really was most excellent. A difficult subject laid out simply & thoroughly in a way that a simpleton like me could understand....

 

I understand from some comments above that it is not technically correct but maybe this is a good thing as it makes it easier to understand....it gets the concept across & I can now look at a model & make an informed judgement based on dihedral, fin/tailplane area & moment arm as to how (relatively) stable it will be.....

[Biggles' Elder Brother - Moderator]

Hi Steve,

 

Thanks for the kind words, glad you enjoyed it. The theory is actually correct - as far as it goes! The point is that there are several different datum points you can take in order to assess the problem from. The most complete and comprehensive is the probably the so-called neutral point. This point takes into account all forms of lift that the aircraft experiences. The problem is that its a very difficult point to practically deteremine. In reality its something of a theoretical concept rather than a practically useful one - good if all you want to do is computer model what's happening. Not so useful if want you are trying to do is trim a model aeroplane to be stable!

 

While the neutral point is a property of the entire assembled aircraft, the centre of lift (which is the concept I am using) is primarily a property of the aerofoil, and its operational conditions to some extent. As a concept its much easier to both understand and determine than the neutral point. Also, in practice, for most models 95% of the usable lift comes from the main wing anyway. So it would seem sensible to use this simplification. The "error" this assumption introduces, if any, is very small indeed for most models.

 

BEB