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Blackburn NA39, intakes, length and radome questions


David Womby

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Sorry - I did not know that. I looked at the drawings referenced above and the S2 intakes are where I think the NA 39 intakes are. Thanks Chocolate Crisps.

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8 hours ago, sloegin57 said:

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 :- 

 

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It may help

if not I will delete the entire post

Dennis

 

There shouldn't be a problem posting the entire drawing at this late date, given that the airplane is no longer in service. I, for one, would really like to see it.

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8 hours ago, sloegin57 said:

 

 

spacer.png 

Dennis

 

I have printed this out at full 1/72.   It's puzzling.   From the intakes back it is an almost perfect match to the Afx NA39 albeit the exhausts on the Afx kit are a bit long as was pointed out in a post above by Andre.  HOWEVER, the cockpit and nosewheel bay locations reflect a shorter front fuselage with a section removed behind the cockpit consistent with the drawing in Allward's book and in Boot's book.   It also measures out to a total length of only 59feet from the tailcone tip to what would be the point of that radome if it didn't have the big probe on it.  the tailcone is a bit undersize, so let's be generous and say 60feet.  That's a lot less than the 62feet 4inches quoted by the FAA museum on their webpage.  So now I am very confused again and think these oddities are perhaps due to the secrecy prevalent at the time this was drawn..


David  

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Here's an extract from a 1963 Flight article:

 

Side Views (1)

 

Here are the side views, realigned using the main wheel centers as a datum. If these drawings are accurate, it appears to me that not only was the fuselage lengthened (moving the cockpit and nose landing gear forward), but also the air brakes were shortened:

 

Side Views (2)

 

I hope this helps clarify the issue.

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13 minutes ago, Space Ranger said:

I hope this helps clarify the issue.

Thanks a lot.  Those are the drawings used in Allward's book albeit with differently worded captioning and no credit is given to Flight.   Does the text of the article describe the airframe changes further?  

 

I'm not sure now how reliable the scaling is of each feature on those drawings anymore although I can well believe the airbrake length was changed during development along with its strakes.   Based on photos, albeit none from exactly the same angle,  I remain convinced something has changed in the relative positioning of the cockpit and nosewheel bay v. the intakes from the 6th machine onwards.  Whether it was by putting a plug in behind the cockpit (as depicted in those drawings) or by shortening the intake trunks, I am not sure.  

 

Still digging but running out of places to look...………………………..

 

David

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6 hours ago, David Womby said:

Thanks a lot.  Those are the drawings used in Allward's book albeit with differently worded captioning and no credit is given to Flight.   Does the text of the article describe the airframe changes further?  

Don't know; I'll have to go back and review the text. I have the entire article, downloaded long before the Flight archive went on hiatus. I'll get back to you.

Edited by Space Ranger
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1 hour ago, Space Ranger said:

Don't know; I'll have to go back and review the text. I have the entire article, downloaded long before the Flight archive went on hiatus. I'll get back to you.

The article is devoted almost exclusively to the S.1. It briefly mentions the S.2, but only to say that it is Spey-engined and under development, with a pair (Nos. 10 and 11) "now essentially complete."

 

Here is another drawing I found in my files. It is the S.2, but the dimensions should be helpful (or maybe not!).

 

r7vfT2

 

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2 hours ago, Graham Boak said:

The top right hand corner tells us that they  came from the Air Publication as numbered, which presumably means Blackburn's Technical Publications department.

Graham, I think we're asking about the source of the drawings used by Allward and Boot in their books.  Like shown in Space ranger's post further up the thread.

 

David

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3 minutes ago, Graham Boak said:

Yes, and Space Ranger has said that these drawings are the ones used in Boot's book - post 59.

I see. I think we may be at cross-purposes here.   I was assuming John's question was about the side view drawings in post 55 rather than the 3 view drawings of the S2 in post 58. Thanks.

 

David

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5 hours ago, David Womby said:

I see. I think we may be at cross-purposes here.   I was assuming John's question was about the side view drawings in post 55 rather than the 3 view drawings of the S2 in post 58. Thanks.

 

David

Just to confirm it was those in post 55

John

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I found this in Boot's book.

"As a result of the outcome of trials and also pilots' comments a new standard of Buccaneer had been designed and was to be introduced on the eighth aircraft. The build of this aircraft, XK 524..." Not XK 534 as shown in the diagram.

He then when on to describe the changes, none of which mentioned the intakes or fuselage length. Regarding the 6th & 7th a/c he mentions the changes to the a.c. system and autopilot development but again no mention of the intakes or fuselage lengthening

John

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Wings of Fame Vol. 14 has an extensive (67 pages!) article on the Buccaneer. Re-reading it last night, I came across the following:

"The first three aircraft of the [20 development aircraft] batch (XK486-488) were to be 'pure' prototypes for the testing of basic systems and flying characteristics. From the fourth aircraft, 'navalized' features and provisions for weapons were to be incorporated, whilst the ninth aircraft and onward were to receive the full systems. Viewed externally, the nose profile was altered from the fourth aircraft, the extended front fuselage and nose cone now having provision for radar."

 

"This aircraft, the sixth [XK491], also inroduced a small lengthening of the forward fuselage, which improved the crew's view slightly by placing the cockpit further ahead of the engine intakes."

 

Of course, there is nothing as to exactly how much or exactly where the front fuselage was lengthened or extended, but it does confirm the change.

 

Sometime back on Britmodeller, there was a lengthy thread about accurizing the old Matchbox kit, and there were a lot of contributions from knowledgeable individuals, including one, if I recall correctly, at British Aerospace with access to the archives. Who was this person? We could use his help. Perhaps there are engineering drawings extant that show these changes in detail.

 

I've been infected with the novel Buccaneervirus! Aaaargh!

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6 minutes ago, Space Ranger said:

I've been infected with the novel Buccaneervirus! Aaaargh!

I am sorry for giving you the virus but thanks so much for finding that.

 

Last night I was poring over more photos and decided I was coming back to my original opinion (based on Allward's book)  that a plug was inserted aft of the cockpit rather than that the intakes were shorter.   So the timing of your find bolsters that belief.  Thanks again.

 

David

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Hi all, I'm just going to park this here for you to pick over, this is the only station drawing I have,  it's from the IPC AP, now if I was going to stick an extra bit into the Buccaneer it would be in the area I've marked in red, anywhere else would mess up the area rule, On the page it has faint pencil marks that I've highlighted in yellow, am I jumping to conclusions or could this be an indication of where a section was added? The bit in blue is what I think would be the prime suspect for a plug 22.55 inch.

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John  

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26 minutes ago, canberra kid said:

Hi all, I'm just going to park this here for you to pick over, this is the only station drawing I have,  it's from the IPC AP, now if I was going to stick an extra bit into the Buccaneer it would be in the area I've marked in red, anywhere else would mess up the area rule, On the page it has faint pencil marks that I've highlighted in yellow, am I jumping to conclusions or could this be an indication of where a section was added? The bit in blue is what I think would be the prime suspect for a plug 22.55 inch.

 

John  

John, thank you.

 

1. I agree the insert has to have been in the area within the red lines.   Looking at photos, there's nothing changed aft or fore of there that I can see.  Also, the bomb bay length seems to have been unchanged.

2.  The area forward of the yellow sloped line (apart from radome changes ahead of the canopy) looks the same in all photos regardless of which prototype or production airframe.

3.  Your blue area is therefore the only possible place and fits my subjective observations.

4.  The yellow highlighted pencil marks are intriguing,  especially the one near the intakes, but I am not sure they signify the fuselage insert.  It looks too long.

 

How did you come up with 22.55inches though?


David

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45 minutes ago, David Womby said:

How did you come up with 22.55inches though?

Not John, but that's simply the difference in the two station numbers at the extremities of the section indicated in blue (244-221.45=22.55), the station numbers being the distance in inches from 'Station 0.00,' wherever that is.

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3 minutes ago, Space Ranger said:

Not John, but that's simply the difference in the two station numbers at the extremities of the section indicated in blue (244-221.45=22.55), the station numbers being the distance in inches from 'Station 0.00,' wherever that is.

Duh!    🤪   I took too many of my stupid pills today.  Thanks.

 

David

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I have just read the Flight article referred to by Mike. It does not mention the fuselage extension and it is such a very comprehensive description of the Buccaneer that I feel that it could not have been written without the cooperation of Blackburn.

It does, however, show those drawings with the 6th and subsequent a/c having longer front fuselages. This seems to be the earliest reference to them and it would appear that they were used in all subsequent publications.

John

 

Edited by John R
Correction of a major error
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Station 0.00 will either be the original tip of the nose or a chosen point ahead of the design.  If there has been a change in length then there should be either an oddity in the station numbers, or differences in station numbers between prototype and production.  This would upset the production jig plans as well as the area ruling, which is carried out from the tip of the nose to the top of the tail. Neither makes a stretch impossible, as on the Tornado ADV, but evidence for this should be visible.

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