Blackburn NA39, intakes, length and radome questions

[John R]

Could it be a perspective problem? If the two pictures are taken from different positions or the a/c centerlines are not at the same angle things will look different.

Below is an example. Assume that you are viewing from the left and the photo of the a/c on the left has been resized to match the length of the one on the right.

Objects on the centreline will be aligned but those off the centreline will not. Note how, in David's comparison the wing root and the u/c doors do not line up.

This not the whole answer as I think that other factors such as the positioning of the camera will also have an effect.

 

 

John

 

[David Womby]

1 hour ago, John R said:

Could it be a perspective problem? If the two pictures are taken from different positions or the a/c centerlines are not at the same angle things will look different.

Below is an example. Assume that you are viewing from the left and the photo of the a/c on the left has been resized to match the length of the one on the right.

Objects on the centreline will be aligned but those off the centreline will not. Note how, in David's comparison the wing root and the u/c doors do not line up.

This not the whole answer as I think that other factors such as the positioning of the camera will also have an effect.

 

 

John

 

Now that makes sense.  I am trying to find pics that are closer in angle but of course I can't.   These are similar but one is taken from below.  Close, aren't they?  What do you think?   Also, should we take this offline if we need further investigation?

 

David

[John R]

Have you seen this collection? There are many 'almost side-on' views and it only takes a small amount of angular difference to make the intake look in a different position relative to the cockpit. There does not, to me, look like there is any difference between the various versions of the Buccaneer. I think that I would go with the first picture from the Yeovilton museum as the definitive version.

https://abpic.co.uk/pictures/search/30/?q=buccaneer&f=type&exact=1&type=&registration=&operator=&code_number=&construction_number=&airport=&country=&photographer=&date_taken=&airshow=&military_unit=&information=&exact=1&search_type=simple

 

Something like this makes you realise how inaccuracies get into model kits.

John

[Colin W]

The Book Modern Combat Aircraft #7 by Maurice Allward, page 22, has a series of 4 profile drawings.

Illustrations are.

1, first 3 development ac

2, 4th and 5th ac

3, 6th and 7th ac 

4, 8th and subsequent ac, Definitive mark 1

 

Drawing 1 and 2 have a long nose probe. 

1, 2, and 3 have longer exhaust pipes by 830mm or 32" compared to 4.

All have same length from wing leading edge to intake lip.

Distance from the last bulkhead (at the hinge of the airbrake) to the rear of the canopy is shorter on 1 and 2. 

The wheel base of 1 and 2 is shorter than 3 and 4 by exactly the same distance as the canopy above. 

Drawings 2, 3 and 4 have the extra section in the nose increasing the overall length. 

Distances from last bulkhead to wing tip, main undercarriage and wing root intake are identical. 

Length of the weapons bay is identical. 

 

My conclusion is that after the 5th aircraft a 256mm or 10" plug was inserted into the fuselage between the front of the weapons bay and the rear of the canopy. The intakes were not affected and remained in place relative to the rear fuselage.

Drawings 3 and 4 show the intakes turned outwards by a few degrees which is complicating the above attempts to use these as a measure. 

 

These measurements are the best I can do from the information available in this book.

 

Hope this helps 

 

Colin 

[John R]

I think that those drawings are the same as those which appeared in Roy Boot's book 'Spitfire to Eurofighter'. Which came first I wonder and where did they originate? I would like to have shown them here but there might have been problems with copyright.

I drew the same conclusions as you when I first saw them.

The frustrating thing is that in less restrictive times there are actual examples in existence which could be measured.

John

[Graham Boak]

Roy Boot was a very senior engineer at Warton, and had come there from a similar position at Brough.  I would rather believe details in his book than any amount of photographic interpretation or journalistic offerings.

[71chally]

Trying to judge differences and dimensions from photographs is a hiding to nothing ultimately.  Aswel as slight angle differences there are then the effects of different focul lengths and how different lenses can cause gentle distortions to an image. 

On top of that, any image we see on the net or reproduced can suffer from distortion of the image itself.

 

I'm sure a fuselage length change was mentioned in an old Flight article, I have got a copy of an NA39 manual somewhere so will try and dig that out.

 

 

[Colin W]

I haven't seen Roy Boots book but Maurice Allward's is dated 1981.

 

Colin  

[Colin W]

The issue about fuselage length is that we know it changed in front of the windscreen. So a change in length will not necessarily clarify the position of the cockpit. 

 

Colin 

Edited April 23, 2020 by Colin W
spelling

[David Womby]

32 minutes ago, Graham Boak said:

Roy Boot was a very senior engineer at Warton, and had come there from a similar position at Brough.  I would rather believe details in his book than any amount of photographic interpretation or journalistic offerings.

OK and apparently (I don't have his book but do have Allward's) Boot's book has a diagram showing the fuselage getting an extension aft of the cockpit.  Does anybody know if his text mentions it?

 

David

[David Womby]

16 minutes ago, 71chally said:

Trying to judge differences and dimensions from photographs is a hiding to nothing ultimately.  Aswel as slight angle differences there are then the effects of different focul lengths and how different lenses can cause gentle distortions to an image. 

On top of that, any image we see on the net or reproduced can suffer from distortion of the image itself.

 

I'm sure a fuselage length change was mentioned in an old Flight article, I have got a copy of an NA39 manual somewhere so will try and dig that out.

 

 

I hope you can find that Flight article. I tried searching their archive the other day but it's still offline.

 

David

[David Womby]

2 hours ago, Colin W said:

The Book Modern Combat Aircraft #7 by Maurice Allward, page 22, has a series of 4 profile drawings.

Illustrations are.

1, first 3 development ac

2, 4th and 5th ac

3, 6th and 7th ac 

4, 8th and subsequent ac, Definitive mark 1

 

Drawing 1 and 2 have a long nose probe. 

1, 2, and 3 have longer exhaust pipes by 830mm or 32" compared to 4.

All have same length from wing leading edge to intake lip.

Distance from the last bulkhead (at the hinge of the airbrake) to the rear of the canopy is shorter on 1 and 2. 

The wheel base of 1 and 2 is shorter than 3 and 4 by exactly the same distance as the canopy above. 

Drawings 2, 3 and 4 have the extra section in the nose increasing the overall length. 

Distances from last bulkhead to wing tip, main undercarriage and wing root intake are identical. 

Length of the weapons bay is identical. 

 

My conclusion is that after the 5th aircraft a 256mm or 10" plug was inserted into the fuselage between the front of the weapons bay and the rear of the canopy. The intakes were not affected and remained in place relative to the rear fuselage.

Drawings 3 and 4 show the intakes turned outwards by a few degrees which is complicating the above attempts to use these as a measure. 

 

These measurements are the best I can do from the information available in this book.

 

Hope this helps 

 

Colin 

Thanks Colin.  It was that drawing that set me off on this search in the first place.🙂

David

[David Womby]

1 hour ago, John R said:

I think that those drawings are the same as those which appeared in Roy Boot's book 'Spitfire to Eurofighter'. Which came first I wonder and where did they originate? I would like to have shown them here but there might have been problems with copyright.

I drew the same conclusions as you when I first saw them.

The frustrating thing is that in less restrictive times there are actual examples in existence which could be measured.

John

I too wonder which set of drawings came first.  No offence to any particular author but I sometimes wonder how much original research some authors do, and not just on aircraft but on any subject.   Another aviation example is the claim, long debunked, that the F-111K would have the long wings of the F-111B/C.

19 minutes ago, 71chally said:

Trying to judge differences and dimensions from photographs is a hiding to nothing ultimately.  Aswel as slight angle differences there are then the effects of different focul lengths and how different lenses can cause gentle distortions to an image. 

On top of that, any image we see on the net or reproduced can suffer from distortion of the image itself.

 

I'm sure a fuselage length change was mentioned in an old Flight article, I have got a copy of an NA39 manual somewhere so will try and dig that out.

 

 

It's because of my surprise at what I read in Allward's book that I started to look for confirmation.  While I agree with the issue of how accurate one can be interpreting from photos, I didn't see any other way to check.  I did contact an ex_Blackburn engineer  who said there was no fuselage extension and that should have been enough but, as of now, I am still leaning towards something has changed in the relative positions of the intakes and the cockpit/nosewheel bay but am still looking and hoping to get a definitive answer or, failing that, consensus.

 

I do appreciate everybody's contributions immensely.  Thanks, all.

 

David 

[Colin W]

It can only really be resolved in the FAA museum with a tape measure! 

 

Colin 😀

[David Womby]

Just now, Colin W said:

It can only really be resolved in the FAA museum with a tape measure! 

 

Colin 😀

Damn that bloody virus!  It's getting in the way of the seriously important stuff in life now.      Well, not really, of course.  It actually puts how unimportant this is into perspective but I'm still interested in the outcome.

David

[sloegin57]

On 25/03/2020 at 18:50, David Womby said:

I know the NA39/Buccaneer prototypes and pre-production machines had various differences.  In  reading Maurice Allward's book, I found a drawing showing some of those changes.   The radome changed to the production style from XK489 onwards but one drawing says '6th and 7th aircraft - AC electrical system, autopilot, extended front fuselage'.  That would be XK491 and XK523.  the drawing shows the extension to be just behind the cockpit.  You can see it in an almost identical drawing on this web page https://www.the-blueprints.com/blueprints/modernplanes/modern-ba-bn/80176/view/blackburn_buccaneer/.  Look at the position of the canopy v the front of the intake on the 2nd and 3rd profiles.

 

Thanks

David

Firstly, I think that the operative phrase in David's opening request is the one I have highlighted - "extended front fuselage".  Has anyone considered the difference in length between the original and production style radomes, the latter possibly requiring it to be folded (as it eventually was) in order to fit standard RN carrier lifts together with the folding airbrake segments.

The N.A. 39 was fairly underpowered, only having two D.H. Gyron Junior DGJ.1's.  The resultant upgrade to DGJ.10's or 21 engines, on production Buccaneer S.1 aircraft,  may well have resulted in the shortening of the entire engine bay from intake to tailpipe and the introduction of the "pen-nib" fairing so apparent in the photographs so far published on this thread.  In my view FWIW, all of these changes would or could possibly give an erroneous impression of a lengthened main fuselage. 

 

Secondly, because of the date of the drawing, January 1960, I have been a bit reluctant to put the drawing I referred to above from Model Aircraft January 1960 into the discussion.  This is mainly due to the prevailing Security restrictions that were in force at the time - Being paranoid was expected and was standard.  This may well have affected the draughtsmans ability to effect what was claimed to be an accurate drawing to 1.72nd scale.

 

Attached a crop from the drawing :- 

 

 

It may help

if not I will delete the entire post

Dennis

 

[David Womby]

Dennis, thank you.    I know your drawing shows the port side but looking at the position of the access panels over the nosewheel bay v  the intake and the cockpit v the intake,  I think it shows a longer intake on the first 5 airframes.   See the latest photo compare I have made below.

 

Thanks again.

 

David

[John R]

Here's a thought. If more powerful engines were installed then the intakes might have had to be enlarged to cope with the increased mass flow. The simplest way to do that would be to shorten the nacelle which some might interpret as lengthening the nose.

Dennis - That drawing shows the relationship between the mid-cockpit frame and the intake to be very like the real thing.

 

Talking with my friend, Chris, yesterday he reckoned that if there was a change it would be almost indiscernible on a model and the only thing that really was bugging us was not knowing the answer.

Infuriatingly there are enough Buccaneers still around to be measured if only we were not prevented from doing so.

 

Why do we do this to ourselves? The only consolation is in 'Catch 22' - as long as know what you are doing is crazy then you must be sane.

 

John

 

 

 

[Graham Boak]

That's a fairly standard comment.  True enough if the difference is spread over the whole length of an aircraft, but when it is just in one specific region then it is discernable to those who have an interest in the aircraft and study its shape.  Those who don't care, won't care.  Those who do, will.  10 inches, if that is what it is, is not indiscernible.  In the end, do you want a true scale model of the aircraft or just a nicely shaped piece of plastic with a reasonable resemblance?

[David Womby]

Does anybody have a copy of Ray Boot's book to check his text, please?

 

David

[David Womby]

45 minutes ago, John R said:

Here's a thought. If more powerful engines were installed then the intakes might have had to be enlarged to cope with the increased mass flow. The simplest way to do that would be to shorten the nacelle which some might interpret as lengthening the nose.

Dennis - That drawing shows the relationship between the mid-cockpit frame and the intake to be very like the real thing.

 

Talking with my friend, Chris, yesterday he reckoned that if there was a change it would be almost indiscernible on a model and the only thing that really was bugging us was not knowing the answer.

Infuriatingly there are enough Buccaneers still around to be measured if only we were not prevented from doing so.

 

Why do we do this to ourselves? The only consolation is in 'Catch 22' - as long as know what you are doing is crazy then you must be sane.

 

John

 

 

 

I know I am obsessing about not knowing but now I am obsessing about why am I obsessing over that!  🤪

David

[John R]

1 hour ago, David Womby said:

Does anybody have a copy of Ray Boot's book to check his text, please?

 

David

I have the book and have seen no references to changes in fuselage or intake length except for that series of drawings which only appeared as part of the description of the planned development program.  However I will have another look.

Regarding Roy Boot as 'the authority' may not be entirely sound as I remember a reviewer remarking, when the book was first published, that there were a number of errors.

Is Roy Boot still around so we could ask him?

[John R]

Another thought. Can anybody please post a picture of the fuselage of the latest Buccaneer from Airfix showing the relation between the fuselage and engine nacelles?

[ChocolateCrisps]

3 minutes ago, John R said:

Another thought. Can anybody please post a picture of the fuselage of the latest Buccaneer from Airfix showing the relation between the fuselage and engine nacelles?

Not sure how accurate to the kit they usually are, but the instructions with the line drawings at the back are available on Scalemates.

[David Womby]

34 minutes ago, John R said:

Another thought. Can anybody please post a picture of the fuselage of the latest Buccaneer from Airfix showing the relation between the fuselage and engine nacelles?

Will that help?  It's an S2 and does have longer intakes.

 

David