Legendary Blackbird - Part 0: Genesis... (3D Printing)

[Serkan Sen]

Couple of months ago I have launched an A-12 Oxcart build based on 1:72  Italeri/Testors kit. Although I did significant progress on the kitbash I was not quite happy with never ending sanding/filling process which you can follow in below thread:

 

After getting my 3D resin printer as birthday gift from my wife and daughters I have decided to print first the kit replacement  parts. But of course I need to have the digital models to print out. Therefore I have started to search best reference drawings to be used in 3D modelling. Also I have imported my own 3 view drawings to CAD.

 

This will be very challenging project and at the end I hope the result will worth all the efforts 🤔

 

By the way, I did not give up A-12 kitbash. It continues in parallel 😁

 

I hope you will enjoy this adventure and share your comments about the progress.

 

Serkan

[billn53]

Excellent! Looking forward to following this topic. 

[Serkan Sen]

I have imported section sketches to CAD xy plane:

 

and then rotated them to yz plane:

 

After then the outer section contours were generated:

 

Next step is to create surfaces from sections.

 

Serkan

[Kushan_Farsight]

I will be watching this with much anticipation!!! Considering the level of detail in your previous project, i expect this will be one of the most accurate blackbird models out there!

What software are you using @Serkan Sen? In terms of generating 3d geometry, have you considered Onshape or Fusion 360? both are free to use and quite powerful tools.  Ive used Onshape to create a large 3D Printed Flying Wing model a few years back, went together great 

 

Some 1/4 and 1/2 scale models to refine the shape

 

 

Full size version main battery/equipment bay

 

May do something similar (but not a flying version this time) for my Baynes Carrier Wing 

 

[Serkan Sen]

On 11/22/2019 at 1:52 PM, Kushan_Farsight said:

What software are you using? In terms of generating 3d geometry, have you considered Onshape or Fusion 360?

At home I use FreeCad for hobby projects, at work CatiaV5. Onshape and Fusion 360 look very powerful and it is great to get free such a tool for hobby projects .

 

Serkan

[Serkan Sen]

The front fuselage surface patches were generated from sections:

 

The port side was created by mirroring starboard side. There  are some areas to be improved but in overall the shape looks correct.

 

 

I have some doubts on windshield and front canopy side views. I will be appreciated if you share your opinion about the correctness of my above drawing.

 

Serkan

[Nikolay Polyakov]

Excellent start, Serkan! 👍

 

3 hours ago, Serkan Sen said:

I have some doubts on windshield and front canopy side views.

Same here, maybe the top portion of the canopy is too forward.

[billn53]

Maybe this can help:

 

 

 

 

 

 

 

 

[Serkan Sen]

On 11/23/2019 at 7:37 PM, Nikolay Polyakov said:

Same here, maybe the top portion of the canopy is too forward.

 

On 11/23/2019 at 9:23 PM, billn53 said:

Maybe this can help:

Bill, Nikolay,

Thanks for your precious feedback. Although there are dozens of side view images on flicker and web it is very hard to find a good reference image without perspective effect and shot parallel to chine line. To me the below one is one of the best reference photo and it was used for comparison with my current drawing:

 

And here is the comparison with early A-12 drawing from Lockheed blueprint (sincerely thanks to Martin from Part 1 thread)

 

Serkan

[Nikolay Polyakov]

6 hours ago, Serkan Sen said:

To me the below one is one of the best reference photo and it was used for comparison with my current drawing:

Yes, looks like it’s a closest match. 👍

[Graeme H]

O my, another thread, and 3D printing involved, be still my beating heart.

[Serkan Sen]

I have realised that I made a fundamental mistake when I started to draw model. I was only focused on the sectional drawings rather than examining the airframe structure from reference pictures and drawings carefully. What I was trying to do was a kind of “reverse engineering” approach.

 

I had already drawn the side view upper and lower surface curves as well as centreline of circular sections. Therefore it was very easy to generate entire fuselage circular sections as well as cockpit area sections:

 

The chine circular blend starts approximately at 45 degrees. The intersection line was generated using inclined plane and created circular fuselage:

 

The blended circular chine was created very quickly using this intersection:

 

The new surface is now very smooth compared to first attempt. The section contour variation along fuselage shows the improvement in modelling.

 

Serkan

Edited November 28, 2019 by Serkan Sen

[Neffan]

Hi Serkan, really interesting… :) I think, soon you will be able to make alot of parts with 3D CAD ... ? Maybe some aircrafts  model-kits....? Congratulations for your work    👍

[Serkan Sen]

1 hour ago, Neffan said:

Hi Serkan, really interesting… I think, soon you will be able to make alot of parts with 3D CAD ... ? Maybe some aircrafts  model-kits....? Congratulations for your work    👍

Thanks Neffan,

Yes I am planning to create RF-8 and TF-8 Crusader front fuselage models to print them out. Many years ago I had started to modify Academy kit to convert but was not able to finish...

Serkan

[Serkan Sen]

The windshield and canopy parts were created by intersecting surface and extruded side view drawings:

 

 

There are some areas to be corrected especially on windshield area but in overall the created surfaces look fine.

 

Serkan

[neil5208]

Looking good Serkan

[Serkan Sen]

The engine cowling was created from circular sections:

 

The next step will be the nozzle.

 

Serkan

[Serkan Sen]

The fully opened nozzle model has been finished;

 

And here are the completed parts together:

 

Next parts will be the spike and inlet duct.

 

Serkan

[Serkan Sen]

Before detailing inlet I have decided to model the wing. Also rear fuselage was added to assembly. It was not easy to find wing profile and give correct shape to the outer leading edge but finally it has been completed:

 

I have also reshaped the engine fairing because the first attempt was not looking right.

 

Serkan

Edited December 4, 2019 by Serkan Sen

[Kushan_Farsight]

Good progress so far Serkan! how much detail are you going to put into the engine nacelles? i saw a picture on the net of a nacelle 'hinged' open to allow access to the engine. This was for the SR-71, but was a similar method used on all variants? It would be pretty neat and i dont think ANY of the kits of the blackbird do this at the moment.



Of course, it is piling on the extra workload, but could be neat! 

[Serkan Sen]

11 minutes ago, Kushan_Farsight said:

Good progress so far Serkan! how much detail are you going to put into the engine nacelles? i saw a picture on the net of a nacelle 'hinged' open to allow access to the engine. This was for the SR-71, but was a similar method used on all variants? It would be pretty neat and i dont think ANY of the kits of the blackbird do this at the moment.

The showstopper is the J-58 engine. The inlet duct and afterburner&nozzle parts are relatively easy.  The internal structure can be modelled upto some acceptable level. But building such model is too much even for my patience limits...

 

Serkan

[Kushan_Farsight]

19 minutes ago, Serkan Sen said:

The showstopper is the J-58 engine. The inlet duct and afterburner&nozzle parts are relatively easy.  The internal structure can be modelled upto some acceptable level. But building such model is too much even for my patience limits...

 

 

Serkan

There is more plumbing on that engine than i think i have in my entire house! I dont blame you!  

If you were going the kitbashing route, there was a 1/72 kit that came with J-58s, but what i can see on the sprue/boxart looks nothing like the actual engine


http://modelstories.free.fr/histokits/SR71_P/SR71_WSN/index.html

Will look forwards to the next update! 

[Serkan Sen]

During the last few days I was busy with the air intakes. Although there are some inlet sketches on internet they are mainly intended to show the principles how the Blackbird inlet works. But none of them has the real shape of the inlet duct. The most realistic sketch I have found was from A-12 Flight Manual Book:

 

Mainly based on this sketch I made the 3D intake model as given below:

 

There are few photos of real inlet duct from front without spike and also from engine side that shows rear end. Here is the front view comparison of 3D model I generated and the real one:

The next will be the spike.

 

Serkan

 

 

[Sting67]

Maybe this:

 

https://www.shapeways.com/product/JQLZJXHSV/sr-71-blackbird-engine-spike-1-72?optionId=60722282&li=marketplace

 

and this:

 

https://www.shapeways.com/product/GDH3ANEJN/sr-71-blackbird-engine-inlet-1-72-testors?optionId=60804741&li=marketplace

 

will help you.

 

Here are some more nice detail pics. They show an YF-12A, but many sections like air intakes, exhaust, gear bays are the same on most versions anyway.

 

http://www.primeportal.net/hangar/howard_mason3/yf-12a/

 

Ramon

Edited December 11, 2019 by Sting67

[Serkan Sen]

9 minutes ago, Sting67 said:

Maybe this and this will help you.

Ramon

Thanks for the links Ramon. I have also seen them when I was looking for replacements. But I am afraid neither the duct nor the spike&inlet have the correct shape.

Serkan