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Legendary Blackbird - Part 5: SR-71A "Blackbird" (1:48 Revell + 3D Printed Parts)


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Yep...as I said in the Revell build thread, it's probably accurate enough for most modellers in their intended market, but if you're looking for more, wait for H/G 👍

 

I know people say in modern model design with CAD/LIDAR and multiple, easy to access internet sources, it should be as easy to get right as it is wrong, but that's not really how the mass market works 🤔 in every possible consumer sense, it's rare for the best product to be the market leader.

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Some updates in this build:

The wing planform from drawing has been printed out and compared with kit wing:

2846.jpg

 

The flaps and slats will be split from wing and flap hinge line will be corrected by adding an insert. The slat tip will be also reshaped to get correct angle. (see the drawings in my previous post).

To bring the tertiary doors and therefore entire engine assembly to the correct position a part has been designed with 9mm insert and all fairings have been added to this model:

2848.jpg

 

Here is the entire exhaust assembly with this insert:

2849.jpg

2850.jpg

2851.jpg

2852.jpg

 

The model is ready to print for dry fit. It will take around 4 hours to get the result.

 

Serkan

 

 

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Here are the kit and printed nose wells:

2869.jpg

2870.jpg

2871.jpg

 

There is around 3mm difference in well and door lengths. I need to find out the reason and I have no access to real aircraft to measure the door size. I have an idea how to calculate it but I need some input data...

 

Serkan

 

 

 

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4 minutes ago, billn53 said:

The printed bay looks 500-percent better than the kit item. I would say 1000-percent, but at least the kit piece had some attempt at detail (unlike some other Blackbird kits I know of).

Hmm, can think of one of those too.  Strangely shallow and flat

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Here is the method I decided to use:

If I get the rim diameter and find a nice side view with minimum perspective distortion then I can roughly calculate the door dimensions. To get the rim dimensions I have to know the wheel size. After a little search in web I found that the wheel is 25x6.75 type VII. A bit reverse engineering but it works most of the time...

 

From Dunlop wheel catalogue here are the specs of the wheel:

2866.jpg

 

where

2865.jpg

 

That means the rim outer diameter is equal to D+2xDF. Using a proper side view I can approximate the dimensions of the door referencing to rim diameter:

2867.jpg

 

and in millimeters in 1:48 scale:

2872.jpg

 

The Revell door length seems a bit longer (46.20 mm) whereas the printed one is 2.5 mm shorter. Now I have to find where this difference comes from...

 

Serkan

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Nitpicking warning! Per the above, DF is defined as the diameter of the flange, not the height of the flange. The correct equation is Rim Flange Outer Diameter = Rim Ledge Diameter + 2 x Rim Flange Height.  For your example, that is D + 2 x Rim Flange Height (<< NOT DF) = 14.00 + 2 x 1.00 = 16.00 inches. 🤪

 

Excellent research, by the way :clap:

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34 minutes ago, billn53 said:

Nitpicking warning! Per the above, DF is defined as the diameter of the flange, not the height of the flange. The correct equation is Rim Flange Outer Diameter = Rim Ledge Diameter + 2 x Rim Flange Height.  For your example, that is D + 2 x Rim Flange Height (<< NOT DF) = 14.00 + 2 x 1.00 = 16.00 inches. 🤪

 

Excellent research, by the way :clap:

You caught me!.. I have realised too that the DF is referring to diameter but not the flange height. You were faster than me... 

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On 1/14/2022 at 10:58 AM, JeffreyK said:

I have some detail sets in the works but will refrain from large "correction" sets, not only will they be unviable I think, also of course we are working on a kit that will be (I hope) as accurate as possible.

I know what I will be doing and that is waiting for the Hypersonic one! When even the Scimitar is being laser scanned for accuracy there is no excuse for basic errors on such an iconic aircraft. 

 

Will

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On 1/14/2022 at 3:21 AM, Alan P said:

 

 

I know people say in modern model design with CAD/LIDAR and multiple, easy to access internet sources, it should be as easy to get right as it is wrong,

I've always felt that to be a passive aggressive comment, used most by anal-retentive rivet counters who knoweth not the #$%^ of which they speak. They usually can't build worth a damn. Perfection takes time, and there are deadlines to meet.

 

-d-

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31 minutes ago, David H said:

I've always felt that to be a passive aggressive comment, used most by anal-retentive rivet counters who knoweth not the #$%^ of which they speak. They usually can't build worth a damn. Perfection takes time, and there are deadlines to meet.

 

-d-

That is a rather sweeping generalisation. Are you saying that LIDAR does not make the job of capturing a shape significantly easier?

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15 hours ago, Scimitar F1 said:

That is a rather sweeping generalisation. Are you saying that LIDAR does not make the job of capturing a shape significantly easier?

Oh no, on the contrary. It has helped a great deal. My comment is limited only to the remark "its just as easy to get things right as it is to get things wrong".  Because, that IMHO is a dangerous oversimplification.

 

The folks at Airfix will tell you that LIDAR is a great help, but it is still just a tool and not the be all and end all of getting the shapes right. They didn't use it on the Spitfire IX kit that's coming up.

 

And "Getting it Right" is more than just about the shape and outline. Getting the proper configuration of something right and not having a mish mash of different blocks, dash versions and variants is a common problem too. Perfection is hard and it doesn't come quickly.

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I think I found the reason of shorter NLG door I modeled:

First comparison with YF-12A drawings:

2873.jpg

 

The blue one is the sketch l used in existing whell well. The pink one is the new sketch. Also a comparison with updated/corrected A-12 drawing:

2874.jpg

2875.jpg

 

The red areas I had somehow forgotten to include in the existing well model...

2876.jpg

 

Also the nitrogen tanks seem that they were modelled a bit undersized. When all these missing areas added the door length matches the value what I calculated...

 

Serkan

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