2x 1:72 Boeing 747SP 'SOFIA'... A 3D printing experiment

[Wolfhound32]

Hi fellow modelers,

 

Again a topic about a big 1:72 model from me, as you are used to

 

This time it's not about a normal kit from my stash, but a 3D printing experiment with some scratchbuilding.

I'm building 2 scale 1:72 NASA Boeing 747SP 'SOFIA' models.

Yes, 2 models.

And, very important, this is an experiment. These are not going to be award winning contest models, o no. I'm aware of that.

This is not the quality of resin printed smooth models, so be warned.

I'll tell you how it started.

 

 

Part 1: SOFIA 1

 

 

A colleague and friend of mine, Erwin, has a  PLA filament 3D printer at home and is experimenting with it. Toys for his kids, design lamps etc.

So in 2020 I asked him to print a knob for my flight simulator. Perfect! The next day it was finished, and I began to think in scale modeling possibilities...

He said there are a lot of freeware models on the internet, like planes and cars etc.

He sent me this link and asked if I would like this model:

https://www.nasa.gov/image-feature/print-your-own-3-d-sofia-model

 

A 1:200 scale NASA B747SP SOFIA. I said well you can give it a try.. if it's not too much trouble to print.

The next day he gave me just the printed nose section, to see if it was worth it.

 

 

Not really.. 

I said: I would only like such a model in 1:72 scale, that would fit in my collection. Would that be possible?

Erwin said no problem, I will enlarge the file for you and print just a part of the nose section. First see the result before printing a whole 1:72 model.

 

In the meantime at home I took my 1:72 Skyland KLM Boeing 747-100 to compare the nose shape of this 1:200 747.

 

 

Quite correct.. mm.

What about converting this Skyland 747-100 into a 747SP..?

I contacted a fellow Dutch modeler, VJ, who once succesfully converted a 1:144 747-200 into a 1:144 747SP for information about how to convert this.

The fuselage of a 747SP is not just a shorter version of a 747 fuselage; especially the tail section and position of the wing root is different.

(for those who are interested: https://modelbrouwers.nl/phpBB3/viewtopic.php?f=46&t=48324)

 

These are some of his pictures he sent me: (credits VJ)

 

 

 

Mm.. I will wait for the result of the printed 747 nose from Erwin. If I start to cut into the quite rare Skyland 747, and it would become too difficult, that would be an expensive mishap.

Also, the NASA SOFIA has a distinguished tail shape compared to a normal 747SP:

 

https://travelforaircraft.wordpress.com ... fia-write/

 

Due to the massive telescope and massive hatch it's not an easy job to scratchbuild something like that.

No, I will wait patiently.

 

In the meantime some information about the NASA SOFIA 747SP: (Source Wikipedia):

 

The SOFIA aircraft is a modified Boeing 747SP widebody (serial number 21441, line number 306; registration N747NA; callsign NASA747). Boeing developed the SP or "Special Performance" version of the 747 for ultra long range flights, modifying the design of the 747-100 by removing sections of the fuselage and heavily modifying others to reduce weight, thus allowing the 747SP to fly higher, faster and farther non-stop than any other 747 model of the time.

Boeing assigned serial number 21441 (line number 306) to the airframe that would eventually become SOFIA. The first flight of this aircraft was on April 25, 1977, and Boeing delivered the aircraft to Pan American World Airways on May 6, 1977.
United Airlines purchased the plane on February 13, 1986, and the aircraft received a new aircraft registration, N145UA. The aircraft remained in service until December, 1995, when United Airlines placed the aircraft in storage near Las Vegas.
On April 30, 1997, the Universities Space Research Association (USRA) purchased the aircraft for use as an airborne observatory. On October 27, 1997, NASA purchased the aircraft from USRA.

Commencing work in 1998, Raytheon designed and installed a 5.5 m (18 ft) tall (arc length) by 4.1 m (13.5 ft) wide door in the aft left side of the aircraft's fuselage that can be opened in-flight to give the telescope access to the sky. The telescope is mounted in the aft end of the fuselage behind a pressurized bulkhead. The telescope's focal point is located at a science instruments suite in the pressurized, center section of the fuselage, requiring part of the telescope to pass through the pressure bulkhead. In the center of the aircraft is the mission control and science operations section, while the forward section hosts the education and public outreach area. The open fuselage has no significant influence on the aerodynamics and flight qualities of the airplane.

https://airwaysmag.com/nasa-conclude-b747sp-sofia/

 

 

A few days later Erwin gave me the first enlarged 1:72 SOFIA parts, the nose + upper deck section.

He took spare filament rolls for this experiment, in this case transparent filament.

 

 

He showed me pictures of the printing process:

 

 

I was happily surprised about the result! Looks quite nice.

I asked him to print some more parts, so next part was the lower nose section with the interior:

 

 

 

 

 

I say let's give it a go! He said the costs were negligible, so he started to divide the 1;200 model into enlarged printable parts.

Again with spare filament in 'happy' colors the next parts arrived:

 

 

 

 

 

 

 

 

 

 

 

 

 

Wow... As you can see not so perfect as I thought.. The engines are straight from Minecraft, a lot of angled and out of shape forms on these parts.. mm.

-The tail has a nice layer structure on the outside

-The upper nose section has a sharp angle under the windows

-The engines and pylons are way out of shape and way too big, these need to be reshaped.

 

Ok, I will start collecting sanding paper, filler and super glue again. Let's give this project a try.

I first removed all the excess material from the parts and after that a dry fit, to see how a 1:72 747SP looks like:

 

 

 

 

 

Quite impressive!

I started sanding. With sanding paper P60 (real rough).

What do you think... almost no result!

 

This PLA is like titanium or something. And the harder I sand, heat comes through the sanding paper so it becomes irritating to my fingertips. And the PLA starts to smell and becomes soft with hard sanding, so this is a problem..

Also you keep seeing the angled structure on the parts. Mm. 

 

 

Meanwhile I contacted Ben Sweezey from V1 Decals, who enlarged his Iron Maiden Ed Force One 1:144 decal sheet for me when I was building my 1:72 Ed Force One.

I asked him the same question to do this for his 1:144 NASA SOFIA decal sheet, and yes, 3 weeks later I had the 1:72 decal sheet for SOFIA.

 

 

Looks good, nice work and thanks Ben  !

 

 

On Flightradar I saw that SOFIA was conducting observer flights from Germany, where she was at that time for an earlier overhaul.

 

 

Some extra information: (source: dsi.uni-stuttgart.de):

 

"SOFIA is a joint project of the German Aerospace Center (DLR) and the National Aeronautics and Space Administration (NASA).
The Deutsches SOFIA Institut (DSI) at the University of Stuttgart coordinates the scientific operations on the German side.
The American scientific operations are planned by the NASA Ames Research Center (ARC) and the Universities Space Research Association (USRA).
Flight tests and flight operations are led by the NASA Armstrong Flight Research Center (AFRC) to the north of Los Angeles.
The NASA Ames Research Center (ARC) to the south of San Francisco conducts the scientific research flights.
To facilitate smooth telescope operations, the majority of DSI employees are continuously posted on site in California."

 

Hence the American / German flag on the fuselage of SOFIA.

 

 

I also asked Erwin if he could find a printable 1:72 Boeing 747 landing gear; it would be nice to put her on wheels as I have no stand for this big model.

He found something, and after a few days he came up with these:

 

 

After removing the excess material very carefully:

 

 

 

 

The wheels were very mashed up somehow, so he printed a better set:

 

 

Looks great. Hopefully this quite fragile gear will hold the massive PLA SOFIA model..

 

Next the Minecraft engines, I just don't want these blobs under the wings. Look at this:

 

 

 

 

Out of the question. I need other better looking JTD9D's. 

Erwin and I searched the internet and finally found a perfectly detailed drawing, which he converted to a printable file:

 

 

 

Perfect! So he printed the first engine:

 

With separate inner cowling and fanblades:

 

 

Look the blob on the left and the almost real JTD9D on the right:

 

 

After that he printed the other 3 engines, in a again another color:

 

Great, this will make SOFIA look much better!

 

 

Back to the fuselage parts.

After hours of sanding it looks like the angled surface has mostly disappeared.

I took spray filler and applied some first layers:

 

 

 

 

Too bad, still visible.

Also the sharp angle in the nose under the cockpit windows needs attention. 

 

I decided to glue the main parts of the lower body as they need to be sanded and smoothed in 1 shape finally.

I took the industrial superglue and bonded the parts:

 

 

 

 

 

The model is getting quite heavy, all these parts are massive!

 

Now the interior is in 1 piece, I added some 1:72 figures to see how this will look when I make a detachable upper fuselage:

 

 

 

Nice! I would like to add a detailed interior to the SOFIA. I will give that a try.

I copied the decals for a dry fit, as these decals are originally made to fit the 1:144 Eastern Express Boeing 747SP kit and not a 'home-made' enlarged 1:72 747SP:

 

I filled the window gaps in the model as the decals will replace these faulty placed holes with correct shaped and placed windows:

 

First the cockpit windows:

 

And the fuselage decals:

 

 

It will fit, no problem.

 

I filled the massive gaps between the fuselage parts and added extra filler to the angled wing roots, ready for sanding a smooth shape

 

 

With all these projects of big kits my days of little and fine sanding are over..

Time to fill up that angle in the nose section also:

 

After the sanding I applied several layers of white primer spray..

 

..but still visible angled surfaces. Time to add more fille, and do some more sanding.

 

The Minecraft-like tail needed special filler attention too.

I applied a thick layer of filler.

 

 

A lot of sanding in this project, but I'm getting used to it!

But looking at this model, with it's rough structure and incorrect shapes it will not be a real beauty...

So I told Erwin this, and this was the start of my second project:

 

 

 

Part 2: SOFIA 2

 

During building SOFIA 1 I began to like the 'little' 747SP with it's distinguished appearance.

The 747 was and is my favorite airliner, and I realized that if I wanted an easier to build and better looking 747SP model, I had to search for another printable model.

So Erwin started searching the internet, and behold, there was another freeware printable 747SP file:

 

Again in 1:200 scale, but this looked already better and smoother than the NASA freeware version.

Erwin started to enlarge this version in 1:72 scale, and divided it in printable parts, 19 in total.

 

This time he used black PET filament, no PLA.

 

And so project SOFIA 2 began to take shape:

 

He sent me the first fuselage pictures:

 

 

 

This 747SP looks much better!!

He gave me the fuselage parts, and the rest of the parts were in the making.

 

 

 

 

 

I taped the fuselage parts together:

 

And compared her with SOFIA 1:

 

Then I started sanding the nose section, this went better:

 

 

 

After the rough sanding, I used some finer sanding paper:

 

 

Better quality this PET filament, with filler applied it will look smoother.

During this sanding process I started thinking what version to make of this normal 747SP. 

I wanted something matching with SOFIA 1, as this is a duo build.

I started searching the Internet on the history of SOFIA, and found this picture:

 

https://www.flickr.com/photos/steelhead2010/50922079036

 

This was SOFIA before her convertion into the NASA version.

She was a written off United Airlines SP, and NASA bought her from the scrapyard to start taking test flights to see if it was possible to convert her into a flying space observatory.

As you can see, a normal looking 747SP with extra NASA decals on her original UA outfit.

So, if this is possible, this will be a unique duo build of 2 SOFIA versions. 

Hence the name SOFIA 2 for this second project.

 

 

Back to SOFIA 1.

I cut of the Minecraft engines, but the wings are kind of hollow so that left some nasty looking gaps in the wings.

 

I filled the gaps with pieces of Plasticard and applied filler, and sanded the wings as smooth as possible.

 

 

 

The wingparts of the fuselage have an angle in it, very hard to sand that smooth...

 

 

 

Meanwhile Erwin gave me the rest of the SOFIA 2 printed parts.

The wings:

 

 

and the tail parts:

 

 

The engines from the SOFIA 2 look very much like the self designed JTD9D's from SOFIA 1:

 

And SOFIA 2 comes with a stand:

 

I compared both the engine sets in size:

 

Mm. The engines from SOFIA 2 are equal in length to a Skyland 747-400 engines:

 

And the self designed JT9D's are smaller compared to the Skyland 747-400:

 

But the 747-400 has CFM65 engines, so it's ok with me. 

 

The tails of both SOFIA models:

 

Very different.

SOFIA 2 has a shift in the wing surface:

 

Erwin says this happened during the printing process. Well ok, it is what it is. 

If there comes a reprint of this model this can be corrected.

 

SOFIA 2 also needs a lot of sanding, here the main wing surfaces:

 

And finally the smoother sanding:

 

 

 

Also the engines:

 

 

I glued the tail parts together and added filler in the gaps:

 

 

 

SOFIA 2 is a real tail sitter, because she has a hollow fuselage but the tail parts all together is too much weight in the rear.

Even on the stand, so she kept tipping over backwards.

I added noseweight just the way I did to my 2 Antonov models: I made a Plasticard rib with M10 bolts and nuts:

 

 

I glued the rib into the nose section:

 

 

No more tipping over, problem fixed.

 

I started to glue the fuselage parts together:

 

 

a 1:72 figure for scale:

 

 

I applied filler and sanded smooth:

 

 

 

Next some layers of spray filler:

 

 

And also on SOFIA 2, the print structure keeps being visible..

 

 

But, SOFIA 2 gets more layers of primer and gloss paint so I think this problem will be solved.

It's already a huge difference in shape and quality compared to SOFIA 1:

 

SOFIA 2 comes with a stand, which is great as I don't want 2 gearless 747 models which are resting on their engines.

SOFIA 1 doesn't have this opening in the fuselage so I added that myself:

 

It fits. So I asked Erwin to print a second stand for SOFIA 1.

 

 

 

The wings of SOFIA 2 are detachable, and hollow which makes the connection between fuselage and wings very weak.

I added balsa supports in the wings to make them sturdy:

 

 

That's better.

Here a duo picture of both fuselages, SOFIA 2 has her first layer of grey primer which already makes her smoother:

 

 

 

The wings of SOFIA 1 can't be made detachable; too less surface for connecting pins or something, so time to glue the wing parts together:

 

 

 

You can also see that neon orange and fluor-green base colors are bad choices for painting.. After several layers of grey and white it still green and orange.

Here with the detachable upper surface parts on the stand:

 

 

Again, a clearly visible difference in quality and shape.

 

I looked at the interior of SOFIA 1 after applying several layers of spray filler and primer, and came to the conclusion that the interior is very rough and out of scale also.

As this is a unique opportunity to add a detailed interior to a special 747 in 1:72 scale, I decided to start a new scratchbuilt interior.

So time to remove the Minecraft block-seats and interior:

 

 

After that, I made a floor of Plasticard:

 

I ordered 1:72 resin airliner seats from HaHen, a very friendly person who added spare seats for free (Cheers HaHen!):

 

 

 

 

After close inspection these seats are a little too small in 1:72 scale.. But never mind, always better than the Minecraft block seats!

I searched the spare box with PE parts from a friend of mine, Perry (who made the An-225 flag) and sorted these PE parts for use in the interior and for the telescope.

 

The telescope will be difficult to scratchbuild, as it's a complicated 'mess' of all kinds of parts and wiring etc.

But we will see.

 

So I started building the interior.

First the seats, which are too small and too low.

So I made chair legs from Plasticard rod:

 

 

 

I removed the cylinder inside the back of the fuselage, which supposed to represent the telescope:

 

Nice.. a project in a project.

 

As I decided to remove the interior, I also need to remove the rough wrong shaped windows on the inside:

 

And some old support PLA walls:

 

I applied Plasticard sheet for a smooth interior:

 

 

 

 

 

I rebuilt the kitchen module:

 

 

 

And the removable computer desk units:

 

And the room beneath the telescope (for making rotating movements during observatory flights):

 

 

 

So, this last picture was taken in April 2022.

After that I decided to participate in the WME2022 contest with my 1:72 Antonov An-225, so I needed my spare time to finish that project.

 

Now I have time to pick up this duo build project again, so I think I will go on with these builds after the summer.

I will finish these 2 SOFIA's!

To be continued..

 

[_alfisti_]

When I saw the first bunch of pics in this topic, I wasn't sure how well this project will went. Then I realized who is building it and my doubts was blown away.

Especially Sofia II looks very good so far, it´is the proof that also filament printers can bring good results. Sofia I is also very interesting with its interior.

I grab a seat and will follow this project.

 

Daniel

[Back in the Saddle]

Great work so fair👍.

 

I guess the file used to print the second model was designed to a higher resolution, resulting in a smoother finish than the more blocky ‘Sofia 1’?

 

Will follow these two with interest!

 

 

[Vesa Jussila]

Really good work and interesting project. I started to thin myself 1/200 Sofia project.

[Ventsislav Gramatski]

What an excellent read that was! Good luck finishing the project - I built a 1/72 3d printed X-Wing last year with an FDM printer and I know the pain (and joy) of going through this process. I'd say, with a very small nozzle and good slicer settings even an FDM printer could be used successfully for scale modeling. 

 

PETG is definitely the better material but it's pretty difficult to print without a heated bed.  

[kev67]

Looks very interesting, I need to buy my self a FDM printer, I see someone on Youtube use SLA resin liquid to paint over the FDM printed parts and then used a UV light to harden it, it worked extremely well although it still requires some sanding but gave a smooth result