S t r e t c h i n g and shrnkg a 737, step by step

[Jessica]

Doing surgery on airliners is often simpler than it may seem. A good candidate for surgery is Revell's 737-800.

Boeing produced 4 different models of the "Next Generation" 737s; the -600, -700, -800, and -900, distinguished by differing fuselage lengths. The -600, -700 and -800 were designed as replacements for the -500, -300 and -400 respectively, and were of similar length and passenger capacity. The -900 has no prior 737 analogue, and is closer in concept to the 757. Revell's -800 kit makes an excellent starting point for conversions to the other 3 versions.

Since the -900 is longer than the -800, there is no getting around the fact that you will need to add extra material to the fuselage. Some people use extender plugs and wrap them in plastic card, but I've found that using two kits can be made to work, since the second kit can be used to make a short fuselage, thus getting two different airplanes for the price of two identical ones. A bargain any way you cut it!

In this exercise, we'll be making a -600 and a -900 from two -800s. Let's call them kit A and kit B.

Cut kit A as follows:

Long nose, short centre section, long tail.

Cut kit B as follows:

Short nose, long centre section, short tail.

Now mix the components up:

For the -900, use nose A, centre section B and tail A. Adjust the length to the proper -900 length by trimming the sections.

For the -600, use nose B, centre section A and tail B.

Use sections of the spare fuselage offcuts as internal splints to keep the kit from going banana-shaped. The cuts have to be placed carefully to ensure that each kit has suffucient fuselage length available. Cutting templates for all versions of the 737 NG are available for download from the Draw Decal website.

These pictures illustrate the process. Kit A is white and kit B is grey.

The cuts are marked with tape. In each case the cut will be made on the side of the tape nearest the wings

The cuts are made

And the parts are swapped around.

Left as-is, the -900's fuselage will be too long, so the nose and tail parts must be trimmed shorter. The offcuts from the trimming may be used as tabs to strengthen the joins. The tail bumper on the -600 must be removed, and the forward emergency exit filled in.

Now comes the moment of truth which will make or break this conversion: Gluing the new fuselage halves together. If it's not done carefully, the fuselage will be bent, or worse, one half will end up longer than the other. Test fit and trim as necessary. Landmarks that must line up exactly are the nose, cockpit cutout, wing mount area and tail. Panel lines are not too critical, because they'll be obliterated during the filling and sanding to follow, and will be restored later.

The first step is the cut the nose and tail sections of the -900 down to the proper length. The -900 is roughly 3 window frames longer than the -800 on both the nose and tail, so the remaining sections need to be cut away to achieve the correct length. Exact measurements for the cuts are on the Draw Decals cutting instructions. The offcut sections may then cut be in half, to be used as splints to help join the cut fuselage sections together. They will need to be trimmed shorter top and bottom so they don't foul the other fuselage half when they're joined. I didn't use a mitre box, so my cuts are a trifle sloppy. I'm not worried, because the joins are going to get a nice wrapping with Miliput to strengthen them further, and cover up any irregularities.

The -600 fuselage halves, showing the splints

The -900 in exactly the same pose

And finally a family portrait. From the top: -600, -800, -900

Edited September 10, 2012 by Jessica

[GEEBEE Z]

Hi Jessica,I cant see the images on here,dont know if anyone else has the same problem.

[HammerUK9]

I also can't see them - and clicking on the 'posted image' doesn't work either.

Tim

[Jessica]

That's funny, I used the same technique to post these as I have for all my images, and I can see them just fine.

In the meantime until the pictures decide to stop hiding, I have the exact same thread up over at Aeroscale.

[cheeley]

I can also see them fine here (very smart they are too)

Chris

[Dave Swindell]

Photo's showing up fine for me in Firefox

This technique works well on other airliners as well eg 2 x Revell Bae146-200 (RJ85's) = 1 x BAe146-100 (RJ70) & 1 x BAe146-300 (RJ100)

[Jessica]

It's also useful for doing DC-9s. Two DC-9-30s when cut properly give you a -10 and -40 or a -20 and -50. There is an article in the third issue of Russel Brown's Airline Modeller magazine, which is still available from AHS. The exact locations of the cuts are shown.

The same technique can give you an 767-400, but since I've never done it I'm not sure whether there will be sufficient length left over for a -200 to be assembled from the short sections. Two 777s will give you a -300 but then you have a "what -if" "777-SP" left over.

[VG 33]

Hi

Very interesting topic.

If you buy the most recent 1/72 Italeri C-130H box there is a booklet inside with a walk-around and the way to produce a C-130H-30 with two boxes as well.

Patrick

[Jessica]

Revell made the window line too low on the fuselage, and I prefer decal windows, so I solved both problems with a judicious application of Miliput. Roll up a snake of Miliput, and apply it to the inside of the fuselage over the windows. Push it so some squeezes out of each window opening, and then sculpt it to the shape of the fuselage contour with water.

The fuselage halves from the inside

And outside

Now at last we can join the fuselage halves together. Once the glue is dry, the seams and joins can be sanded down and cleaned up.

[Romeo Alpha Yankee]

Great topic Jesse. I have only done the chop to a -700BBJ many years ago. Now I have the method to do the others. Also nice to see the 146 and DC-9 mentioned.

[cuprar]

I like this!

[pinky coffeeboat]

Thanks Jessica, it's all very handy seeing this being done.

[depressed lemur]

I would never have thought of this. Thanks for the lesson

[Jessica]

Basic filling and sanding are done and the wings are glued on. Time for a little more filling around the wing joins and then the primer coat.

The winglets were borrowed from a Daco kit that won't need them. It turns out that Daco winglets are too tall for the classic 737s, which makes them just about right for an NG except for the short chord. I'll need to fill in that missing piece of leading edge.

Now a little fun. Here's the -200 that I'm doing for the Aeroscale's Airfix Campaign. Note how different the NG wing is when compared to the original. Apparently this wide wing makes the -600 a little more challenging to fly than its stablemates.

[madaboutmodels]

Looking good.

[Jessica]

The primer reveals where I need to do more filling and sanding.

They look a lot worse in person, but showing you what looks ugly still is what primer is for.

[Jessica]

The next round of filling and sanding is done, priming to come.

And just for fun, the base -800 kit I'm building alongside these two.

[Romeo Alpha Yankee]

So my cut and shut conversions aren't the only ones that look like this after putty and sanding. Will you be worrying about rescribing when you are done?

[RNoAF Aerobatic Team]

This should be pinned by the Mods.... MISH?

[Jessica]

So my cut and shut conversions aren't the only ones that look like this after putty and sanding. Will you be worrying about rescribing when you are done?

I'll restore the major panel lines. I'm not a big fan of panel lines on 1/144 models; they're way out of scale. But still, you have to have something to keep it from looking like a toy.

[SHAR67]

I draw my panel lines on with a draughting pencil as it looks more in scale with the 1/144 models. You can't always see the panel lines on the real things, you can see what I mean in these pictures I took today there not that visable.

This was taken about 25 feet away.

This was about the same but different aircraft.

Heres another of a larger jet and the panel lines are not that clear at this distance.

This was a little closer.

And this one shows the more colourful the aircraft the less you see of the panel lines.

Hope these are of help.

Clive

Edited September 19, 2012 by SHAR67

[Jessica]

That exactly illustrates my point Panel lines are more visible from the dirt they trap rather than being a huge trench in the surface of the aircraft. If we were to scale up even the finest engraved panel line to 1/1 scale it would be massive. Drawing them with pencil often works much better than the finest possible scribing.

[Lawnguylander]

You can see the panel lines on the Air China jet's engine nacelle from a mile away- Some lines seem more prominent than others...

[garryrussell]

For these reasons I much prefer the light raised lines than the current trend of trenches.

[madaboutmodels]

any work done on these jess?