1:72 Merlin engined Halifax corrections

[John Aero]

Cheers Tony. Yes the four blades are due to go in a new mould soon.

As soon as I can get these darn measurements sorted out I can move on. I have just done an interesting excercise by importing the photo Occa has used into my drawing programe. Problem no1 is a pixilated photo and only one engine presented any chance of a reasonable measurement. So working within the best focus, I used the inner stub wing to calculate a ratio with the width of the engine nacelle. I made this to be 3.1 so with this ratio I came up with the following figures. Engine nacelle (inner) width 46.5" and the spinner came out at 26.5" (this latter was not the easiest because of prop blur and pixellation).

However I think I'll throw in another wobbley, are the outer nacelles the same width as the inners. The cowls are totally different as are the bulkheads. The outers are set further back into the wing. I thought of this because keeping an open mind, if there is a difference, one person is measuring one nacelle and another quoting measurements for the other from whatever source. In the back of my mind is the pre-history of this design and something Harry FM mentioned as to seeing letters from the designer Volkert ref the Vulture and the fact he never wanted Merlins in the first place. He much prefered air cooled engines. If any design work was carried through from the Vulture nacelle installation (as in the Lanc) then the outer nacelles were an add on and designed to take the Merlin not the Vulture.

John

Edited March 7, 2012 by John Aero

[tonyot]

Cheers Tony. Yes the four blades are due to go in a new mould soon.

As soon as I can get these darn measurements sorted out I can move on. I have just done an interesting excercise by importing the photo Occa has used into my drawing programe. Problem no1 is a pixilated photo and only one engine presented any chance of a reasonable measurement. So working within the best focus, I used the inner stub wing to calculate a ratio with the width of the engine nacelle. This I made to be 3.1 so with this ratio I came up with the following figures. Engine nacelle (inner) width 46.5" and the spinner came out at 26.5" (this latter was not the easiest because of prop blur and pixellation).

However I think I'll throw in another wobbley, are the outer nacelles the same width as the inners. The cowls are totally different as are the bulkheads. The outers are set further back into the wing. I thought of this because keeping an open mind, if there is a difference, one person is measuring one nacelle and another quoting measurements for the other from whatever source. In the back of my mind is the pre-history of this design and something Harry FM mentioned as to seeing letters from the designer Volkert ref the Vulture and the fact he never wanted Merlins in the first place. He much prefered air cooled engines. If any design work was carried through from the Vulture nacelle installation (as in the Lanc) then the outer nacelles were an add on and designed to take the Merlin not the Vulture.

John

Thats great new John, thanks!

I think that you have a point about the inner and outer nacelles being different and like you say it would explain the different measurements being quoted.

All the best

Tony O

[chaddy]

However I think I'll throw in another wobbley, are the outer nacelles the same width as the inners. The cowls are totally different as are the bulkheads. The outers are set further back into the wing. I thought of this because keeping an open mind, if there is a difference, one person is measuring one nacelle and another quoting measurements for the other from whatever source. In the back of my mind is the pre-history of this design and something Harry FM mentioned as to seeing letters from the designer Volkert ref the Vulture and the fact he never wanted Merlins in the first place. He much prefered air cooled engines. If any design work was carried through from the Vulture nacelle installation (as in the Lanc) then the outer nacelles were an add on and designed to take the Merlin not the Vulture.

John

Interesting observation that John. I've been looking at some photographs myself and gained the distinct impression there did seem to be a difference in widths in some of those photographs. I put it down to the angle the photographs were taken or some lens distortion at the edges of the photographs, or some other effect. Now you've commented on it I'm not so sure.

Cheers

[John Aero]

Well I got down to Hendon today for a very quickly arranged visit to measure the Halifax. A thoroughly helpful member of staff had sorted out out the formalities very quickly and assisted me to measure up what parts we could. Unfortunately so much is missing but I was able to crawl into the back of the stbd nacelle to ascertain an accurate width of the nacelle, great fun over the white limestone pebbles of the display. I came out looking like a chalk miner! I got all of the data I needed to fill in the blanks. I am going to sit on my findings until I've finished my bits as I don't want some former soviet lackey to use my data until we Britmodellers have benefited first. I had a very good visit all told.

I do know who did the CAD for Revell (but no names, no packdrill as we used to say) and the drawing source was Handley Page but don't get excited because somewhere there was a cockup with the data.

Now I have seen comment that the Revell fins are wrong. In fact I now think possibly they're not. I was trying to photograph the fins when I noticed a row of rivets and this carried my eye to the top and bottom of the fin. The rivets appear to be equi-distant from the rudder post, but the top and bottom fin tip chords are different. (nothing to do with the top half being taller than the bottom). I've not thoroughly checked this but the Matchbox and both Merrick and Granger appear to be wrong.

Occa had a question about what the lower "bumps" are under the engine front cowl are. I think they were clearance for the Glycol header tank drains.

John

Edited March 7, 2012 by John Aero

[keefr22]

I am going to sit on my findings until I've finished my bits as I don't want some former soviet lackey to use my data until we Britmodellers have benefited first.

Good thinking John!! Looking forward to being able to purchase the fruits of your labours!!

Keef

[occa]

Well I got down to Hendon today for a very quickly arranged visit to measure the Halifax. A thoroughly helpful member of staff had sorted out out the formalities very quickly and assisted me to measure up what parts we could. Unfortunately so much is missing but I was able to crawl into the back of the stbd nacelle to ascertain an accurate width of the nacelle. I came out looking like a chalk miner! I got all of the data I needed to fill in the blanks. I am going to sit on my findings until I've finished my bits as I don't want some former soviet lackey to use my data until we Britmodellers have benefited first. I had a very good visit all told.

I do know who did the CAD for Revell (but no names, no packdrill as we used to say) and the drawing source was Handley Page but don't get excited because somewhere there was a cockup with the data.

Now I have seen comment that the Revell fins are wrong. In fact I now think the reverse. I was trying to photograph the fins when I noticed a row of rivets and this carried my eye to the top and bottom of the fin. The rivets appear to be equi-distant from the rudder post, but the top and bottom fin tip chords are different. (nothing to do with the top half being taller than the bottom). I've not thoroughly checked this but the Matchbox and both Merrick and Granger appear to be wrong.

Occa had a question about what the lower "bumps" are under the engine front cowl are. I think they were clearance for the Glycol header tank drains.

John

Ah thank you John for thinking of my question.

And of course you must keep me in tension about the actual width as you know I would love to know if I am right or wrong ...

Just kidding lol, where can I buy your stuff when it's finished?

Alone the radiator intakes you made certainly look the part, much better than I ever could accomplish.

Edited March 6, 2012 by occa

[woody37]

John, thankyou for all you're doing, count me in for a few sets when they roll of the Aero production line

[feddawg]

Nothing beats measuring the real thing. I can remember 15 years ago getting a press pass and attending the setup day for an airshow at which with a 12' ladder, plumb bobs, a tape measure, and the aircrews blessing I took accurate measurements from a B-52H engine nacelle. Do what you want with photos and line drawings the real thing trumps them all!

[DaveCS]

Wow.. I love coming here and reading this thread!!! I know it's been said before but if John (and others) are able to figure this stuff out, and since Revell is in Europe along with the Halifax at Hendon.. why couldn't someone have arranged for effective measurement etc. ?

I know.. I know.. it's been asked..

Cheers,

Dave

[lufbramatt]

I'm pretty sure this model was designed by BraZ model, like the lancaster and B17. Not sure where they are based?

[John Aero]

The answer is simple. The is no specialist input and minimal research input by the "big" firms. They gather in info from whatever sources they choose or can obtain easily and work in secrecy. Historically working drawings were prepared and given to the pattern shop and this is where most errors came in providing the input info was good in the first place. Why do you think that the wing sections are inverted on the Airfix Henschel 123 and Lysander. Because the pattern maker who saw the section on the drawings hadn't a clue about aeroplanes. His last job might have been a doll or a ship.

Now the info is given to some clever young people who are talented with CAD. If there is no one with real aircraft knowledge and a good eye standing over them then mistakes will get through unnoticed.

This is probably why the Halifax has been poorly designed IMO, because with expert supervision and with a simple slightly more parts breakdown Revell could have cleaned up on the Halifax. No fairings on the tops of the wings would have meant an easier transition to a Hercules version needing only a new sprue with the relevant Hercules parts. Bugger the tiny problems like "oh god the bog window isn't opaque" and get the main airframe right. It's not difficult just talk to people who know.

A classic of modern times is this true tale. A representative of a plastic model firm went to a certain country to get a kit made. he took with him photos ,drawings and measurements, everything that was needed. When the chap was finally taking his leave, he was asked "were is the model you want us to make". They clearly expected a model kit to scan.

John

Wow.. I love coming here and reading this thread!!! I know it's been said before but if John (and others) are able to figure this stuff out, and since Revell is in Europe along with the Halifax at Hendon.. why couldn't someone have arranged for effective measurement etc. ?

I know.. I know.. it's been asked..

Cheers,

Dave

[Aeronut]

Now the info is given to some clever young people who are talented with CAD.

Clever with a computer they may be, but given an original blue print they have a habit of scaling off the drawing and ignoring the warning written on the drawing sheet of "DO NOT SCALE". They are also seemingly cluless to the old draughting practice of adding the suffix NTS to a dimension when the original draughtsman found it easier to change just the dimension rather than redraw the whole thing.

I did have a Draughtsman's Licence - and boy did I abuse it.

* NTS = Not To Scale

[Seahawk]

Clever with a computer they may be, but given an original blue print they have a habit of scaling off the drawing and ignoring the warning written on the drawing sheet of "DO NOT SCALE". They are also seemingly cluless to the old draughting practice of adding the suffix NTS to a dimension when the original draughtsman found it easier to change just the dimension rather than redraw the whole thing.

I did have a Draughtsman's Licence - and boy did I abuse it.

* NTS = Not To Scale

I am not a draughtsman but have this nagging suspicion that the weedy prop blades that seem to be a recurring problem in some manufacturers' kits result from patterning blades from a simple head-on view which of course takes no account of blade pitch, rather than the zero-pitch "developed profile" provided by better drawings. I find it hard to believe that it could be something so elementary, but ...

[Work In Progress]

I think that theory is very likely, Seahawk.

[John Aero]

You're absolutely right. It is any easy one to fall for especially if you don't know aircraft, like the measure the plan and forget the dihedral effect. It's much more difficult to flatten out a complex wing shape.

John

I am not a draughtsman but have this nagging suspicion that the weedy prop blades that seem to be a recurring problem in some manufacturers' kits result from patterning blades from a simple head-on view which of course takes no account of blade pitch, rather than the zero-pitch "developed profile" provided by better drawings. I find it hard to believe that it could be something so elementary, but ...

[chaddy]

Clever with a computer they may be, but given an original blue print they have a habit of scaling off the drawing and ignoring the warning written on the drawing sheet of "DO NOT SCALE". They are also seemingly cluless to the old draughting practice of adding the suffix NTS to a dimension when the original draughtsman found it easier to change just the dimension rather than redraw the whole thing.

I did have a Draughtsman's Licence - and boy did I abuse it.

* NTS = Not To Scale

I've recently retired after over 40 years experience in design offices (not aero engineering, however). I can tell you every word is true. I've seen the development of CAD and, whilst it is a wondrous thing, in the right hands, it has been used , in my opinion, been used to dilute the skills of the drawing office. Older, experienced draffies were overlooked, sidelined and made redundant in favour of younger keyboard jockeys. Whilst I admit many of the younger chaps had excellent skills using the software, what they lacked, almost to a man, was any understanding of basic principles of design. To them it was just something they created, an end in itself. The old draughtsman new that is drawings were merely a means of conveying information so that something real could be built or manufactured.

It's not the fault of these people, it's the fault of companies eager to increase productivity and reduce costs. The mess-up with the Halifax pales into insignicance with some of the things I've seen in the real world, particularly as companies set up more and more "low cost" centres around the world.

Cheers.

[lufbramatt]

Clever with a computer they may be, but given an original blue print they have a habit of scaling off the drawing and ignoring the warning written on the drawing sheet of "DO NOT SCALE". They are also seemingly cluless to the old draughting practice of adding the suffix NTS to a dimension when the original draughtsman found it easier to change just the dimension rather than redraw the whole thing.

I did have a Draughtsman's Licence - and boy did I abuse it.

* NTS = Not To Scale

As a "clever young person who is talented at CAD", I'd like to politely disagree with this- I graduated in 2006, so fairly recently, and before we were let loose on the CAD computers, we were given a good grounding in traditional drawing with a pencil (by an ex-Brush engineer that worked on the Intercity 125 locomotives), including laying out projections, dimensioning and annotating drawings. Now I don't profess to being able to hand draw technical drawings to the same standard as a professional draughtsman with years of experience, but I can read and understand a technical drawing and understand that dimensions > outlines. I know lots of people about the same age as me (27) that can also read a drawing properly . . . careful with tarring everyone with the same brush ;-)

Lots of the parametric CAD software only works properly if you give it the right data, and the user interfaces of the programs are closely related to traditional drawing techniques. Dimensioning features in particular works identically to how a drawing would be dimensioned, otherwise the tolerances in the 3D model stack up in exactly the same way as they would if a machinist was working to a paper copy of a drawing.

Edited March 8, 2012 by lufbramatt

[John Aero]

A delightful friend the late Alan Perry was part of the Concorde design team and even into his 70's after he had retired he was often asked to go back to BAC to help sort out problems often when the computers and CAD programmes had crashed. He would stand before the 'Caddies' and take from his top pocket a pencil and say I have the technology, now do you know what paper is?

John

I've recently retired after over 40 years experience in design offices (not aero engineering, however). I can tell you every word is true. I've seen the development of CAD and, whilst it is a wondrous thing, in the right hands, it has been used , in my opinion, been used to dilute the skills of the drawing office. Older, experienced draffies were overlooked, sidelined and made redundant in favour of younger keyboard jockeys. Whilst I admit many of the younger chaps had excellent skills using the software, what they lacked, almost to a man, was any understanding of basic principles of design. To them it was just something they created, an end in itself. The old draughtsman new that is drawings were merely a means of conveying information so that something real could be built or manufactured.

It's not the fault of these people, it's the fault of companies eager to increase productivity and reduce costs. The mess-up with the Halifax pales into insignicance with some of the things I've seen in the real world, particularly as companies set up more and more "low cost" centres around the world.

Cheers.

[John Aero]

To lufbramatt, you are right. It does boil down into the old GINGO (garbage in garbage out). But it does need a 'specialist' overseer to say "hang on, check that shape again". How on earth did the Halifax get as far as the tool room.

John

Edited March 8, 2012 by John Aero

[occa]

To lufbramatt, you are right. It does boil down into the old GINGO (garbage in garbage out). But it does need a 'specialist' overseer to say "hang on, check that shape again". How on earth did the Halifax get as far as the tool room.

John

That is the exact point !!!!

[John Aero]

Just a passing thought. The Boulton Paul C II type dorsal turret used the front part of the C I nose turret (designed for the Halifax) so these two parts should be identical.

John

[John Aero]

Just some of the update work on the replacement saxophone exhausts. They are quite a complex and bulbus shape especially on the inside, but being allowed to examine them closely helps. these will (hopefully) be metal. The black one has just been felt tipped and isn't finished.

John

[woody37]

Great to see the progress John,

all these positive waves

[tonyot]

Looking great John, I`d best go and buy a couple more Halifax kits!

Keep up the good work,

Tony O

[John Aero]

I don't know how many follow this http://forum.keypublishing.co.uk/showthrea...634&page=14 but Cees has been recreating a complete Halifax cockpit for almost three years from original drawings and mostly original fittings. Note the slope of the fuselage top.

John