AMP 1/144 SOFIA 747SP

[zebra]

I'm going to build the AMP 1/144 kit of NASA's Boeing 747SP flying observatory 'SOFIA' (Stratospheric Observatory For Infrared Astronomy). SOFIA was a highly modified ex-United Airlines 747SP with a large telescope added to the rear fuselage.

 

Here's the kit:

 

 

It's the ex-Eastern Express 747SP (which was also tooled in Ukraine) with a new fuselage and new sprues for the telescope and the cavity it sits in. Quite a nice looking decal sheet although it's a shame there's no windscreen decal, and it would have been helpful if they'd given us a separate blue stripe for the bit of the cheat line that goes over the door. There are also vinyl masks and a couple of 3D printed components for the telescope. Also available at a much more reasonable price than the Eastern Express kits ever were!

 

I'll be building it with the door open and the telescope on show - it would be a waste not to. I've made a start - assembled the cockpit parts and cleaned up the fuselage - I'll post photos when I've made a little more progress.

 

more soon

Julian

 

[Marlin]

WOW

I didn't know that this was already released. 

I plan to get one of these my self. 

So I'll tag along here and see how it builds. 

 

/Bosse   

[JOCKNEY]

Hi Julian

Go large or go home 

Great choice mate, best of luck with this one

Cheers Pat 

[bianfuxia]

I didn't even know this kit existed 48 hours ago

Didn't know it had been released until I saw your post which...I am so here for (my first go at that 2010s internet parlance). 

 

I'm keen to get this kit myself so I'm looking forward to seeing how you go with it. 

[zebra]

On 9/10/2024 at 5:28 AM, JOCKNEY said:

Go large or go home

It's getting into where-am-I-going-to-put-it territory! After this and my recent 1/72 Wedgetail I think the next build will have to be a lot smaller

[zebra]

Not had a lot of time over the last week or so, but made some progress in fits and starts. Thanks to the telescope, there's a bit more to do before closing up the fuselage than in the average airliner build, so it's mostly preparing subassemblies so far.

 

 

I've assembled wheel wells and cockpit parts. Cockpit has been painted grey, I'll paint the IP and coaming in a darker colour and I'll add another colour to the seats, but that's all that I'll do on the cockpit - very little will be visible. The bits of the telescope cavity that need to be in zinc chromate have been painted as well, and the inserts in the door have been added.

 

A couple of things to watch out for if you're building it - firstly the concave curved fairing at the back of the door opening shouldn't be in zinc chromate, as the instructions would have you paint it - all the photos I've found show it in a near-black colour. I think NATO black should do it. Secondly the 3D-printed part for the framework that separates the upper and lower parts of the telescope itself is very, very fragile - I've broken it several times already - so take care! I've dealt with it by knocking up a replacement in Fusion360 and printing it - it's sitting in the 3D printer as I type this.

 

more soon

Julian

 

[zebra]

The telescope has been assembled and painted:

 

 

The mirror and the round bit on the left, which attaches to the bulkhead, are kit parts. The rest is my 3D-printed part which I printed as a single piece. The telescope frame in the kit was in 4 parts - the upper and lower parts of the frame and the secondary mirror (the bit at the top) in plastic and the framework around the sides (this was the fragile piece) in 3D printed resin. I think my approach has resulted in a much sturdier part. I've used chrome bare metal foil on the mirror, although it doesn't look like it in the photo!

 

Here it is installed in the fuselage:

 

And the assembled fuselage, with a few other bits in the background:

 

 

more soon

Julian

 

 

 

[zebra]

Tail cone and (huge) fin are on. The tail cone fits quite well, the fin doesn't! I think the problem is that the fin is from the original 747SP kit but the profile of the rear fuselage has changed slightly with the addition of the bulged fairing for the telescope. Should be able to sort it out with a bit of filler though.

 

 

more soon

Julian

[bianfuxia]

Looking great so far!

 

Inspired by this, I just pulled the trigger on it myself, ordered direct from Ukraine✅🇺🇦

[zebra]

With the fit of the fin sorted out I've moved on to the wings and engine pylons. The wings are engineered in a similar manner to a lot of recent Ukrainian airliner kits - the upper half includes the trailing edge and a small section of the lower wing ahead of the trailing edge, which the lower half butts up against. All very well but the join isn't on a panel line or a flap or aileron hinge line, and the lower half is slightly too thick so there's a step to deal with. I dealt with the step by attacking the inside of it with a coarse (120 grit) sanding pad - this actually made quite quick work of it and I ended up with something that fits fairly well. I've filled the join with CA and blended it in. It'll need a bit of rescribing.

 

The pylons - again, in typical Ukrainian short-run style - are made up of more parts than a mainstream manufacturer would have used. Two of them are in four parts - front and back halves, split lengthways - and two of them have an extra two for a fairing on the upper forward section. A little tricky to align but I got there.

 

Here's how it's looking tonight:

 

 

more soon

Julian

 

[zebra]

Finally got around to assembling the engines. These are the worst-fitting parts so far - although, to be fair, they're the only really poorly fitting parts so far. The fan (which attaches to the hot section) has a ridge around it that's supposed to fit into a groove inside the nacelle - the problem is either the ridge on the fan is too wide or the groove is too shallow, because the nacelle halves won't go together as is. Scraping out the groove a bit did the trick.

 

So now I've got 4 (mostly) assembled engines:

 

 

Next I'm going to test fit them to the pylons and test fit the pylons to the wings, so that I can decide what sequence to assemble them in - ie do I want to fit the pylons to the wings before or after the wings are attached to the fuselage, and will the engines fit well enough to be able to leave them off until I've painted the airframe (which is how I'd prefer to do it)?

 

more soon

Julian

 

[Mike N]

Great work so far, Julian!

 

I've been thinking of getting this kit, so am keenly following your experiences with it.  

 

Mike 

Edited October 13, 2024 by Mike N

[zebra]

Test-fitting the wings today:

 

 

There are three main components here - the centre section, which includes the lower half of each wing out to the inboard engine pylon, and the main wing parts. There are a few issues here - none of them all that hard to deal with, but with a little effort the fit gets a lot better:

 

Similar to the outer wings, fin and tailplanes the trailing edge of the inboard section is part of the upper half and the join is a few mm forward of the trailing edge. As with the other parts there's a step to deal with, because the back end of the lower part is a bit too thick. This is fairly easy to deal with - I've got a small 120 grit GodHand sanding block which I use on the inside of the lower part to thin it down until there isn't a step any more.

 

Then some adjustments are needed to get a good overall fit between the upper and lower wing parts - there's a mismatch of about 0.5mm in chord, leading to a pronounced step at the leading edge. Trimming a bit off the flap track fairings and scraping a bit off the back end of the lower part resulted in a much better fit.

 

The outboard end of the lower part is a bit flimsy and needs something to support it from the inside - a bit of scrap sprue was about the right size for this.

 

When offered up to the fuselage, the belly fairing fits quite nicely but there's a bit of a gap on top at the root. I think this is caused by the wings splaying out a bit - it'll close up. It'll need some support at the root to get a strong join - I think I'll do this with some plastic card strips on the inside of the root.

 

Next steps from here: I'm going to assemble the wing into a complete, full-span part. It's then going to need a bit of rescribing. After that I'll attach the engine pylons, then I'll attach the wing to the fuselage.

 

I've also test fitted the engines to the pylons. With some very minor fettling I've got a pretty good fit so I'm going to leave the engines off and paint them separately from the airframe, and attach them at the end.

 

More soon

Julian

 

[Marlin]

Looks great  Julian @zebra

 

I really must get my own one of this. 

/Bosse

[zebra]

Wings are on:

 

 

My efforts to improve the fit of the upper and lower wing halves paid off again - in that process I reduced the span of the lower centre section part sufficiently to virtually eliminate the gaps at the roots. Using masking tape to flex the wings up while the glue cures has resulted in pretty much no gap at all. 

 

It wasn't completely without fettling though - there was a bit of a mismatch between the wing root profile and the profile of the fairing on the fuselage, which looked like the wing was about half a mm too far forward, so I removed a bit of material from the back of the centre section part until I had something I was happy enough with.

 

The belly fairing itself is a fairly good fit - slightly wide at the extreme front and back ends, which will be easy enough to deal with, but no step on the belly as often happens. Removing material from the back end opened up a gap at the front though, which I've dealt with using thin plastic shims and CA.

 

More soon

Julian

 

[exdraken]

Great work, intriguing design!!

 

Nice!

[zebra]

Wing joints have been cleaned up and a few detail parts added, and it's ready for paint.

 

 

I hope I'm not going to regret adding the long pointy bits on the wingtips (I think they're UHF antennae) at this stage - they seem to be asking to be snapped off - so I've bodged together a couple of cardboard sleeves that will hopefully protect them.

 

Since taking this photo I've masked the windscreen using the vinyl masks provided in the kit and I've started priming.

 

more soon

Julian

 

[Marlin]

Looks great Julian.

Looking forward to see it painted.

/Bosse

[zebra]

The white is done:

 

 

Also, the pointy things on the wingtips have come off. Whilst looking at online photos to work out where the demarcation between the white and the grey goes I noticed they're not actually present in most photos - they only seem to have been there quite early in SOFIA's life. There was an avionics upgrade around 2012, so I guess they may have been removed then. Which saves me from having to protect (and later on, fix) them. Thanks NASA!

 

more soon

Julian

 

[CliffB]

I'm just catching up.  What an interesting subject - a great choice 👍

[Mike N]

Looking really good so far, Julian!

 

On the back of this thread, I've ordered myself one

 

Looking forward to seeing your build progress.

 

Mike 

[zebra]

And now the grey's done as well:

 

 

Metallic bits next - mainly the leading edges

 

more soon

Julian

 

 

[bianfuxia]

Getting closer and looking good!

[zebra]

Painting is finished:

 

 

Decals next. I've put a few of them on already - I'll share a photo tomorrow - and I have to say they're not all that good. Firstly they're a bit brittle - not a problem for most of the decals, but not what you want for a cheat line, particularly one that has to go around the nose. Secondly there's not a separate decal for the bit of the cheat line that goes on the telescope door, just a continuous cheat line decal that extends from the tail to a point a few mm in front of the door. Fine if you're building it with the door closed (although I'd be concerned about the brittleness of the decal and the contours it would have to go over) but I'd expect most modellers building this kit would want the telescope to be on show.

 

Fortunately I also have the V1 Decals sheet for this aircraft. As I'll be cutting up one of the cheat line decals to cater for the telescope cavity, I'll have a bit of spare decal to use to 'touch up' bits where the brittle decal breaks. I'll then use some of the V1 cheat line for the bit that goes on the door.

 

I've also been painting engines and assembling wheels. One of my bugbears with Ukrainian airliner kits is the wheels usually come in two halves, and assembling them and dealing with the seams is a PITA. In this case there are 18 wheels to deal with! 

 

more soon

Julian

 

[zebra]

First decals are on:

 

 

I've done the cheat line on the other side as well - trying to get it to conform to the more complex shape around the other side of the telescope cavity, plus the nose, was tricky and some touching up with spare decal will be needed. Also the three components of the cheat line weren't quite long enough - there's a small gap to fill.

 

more soon

Julian