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Viking

Correcting the Revell 737-800

32 posts in this topic

I've been asked to summarise the topic on correcting the 737-800 to contain just the relevent bits from the build, so here goes.

I first searched this forum for comments on the kit. What I found was the people who know more about this accuracy stuff than I do, is that there are 3 major problems with it,

1) The window line is too low.

2) The winglets are way too short.

3) The engines are from the earlier series 737's with flattened rims and undersides. They look completely wrong.

I've done all this by eye and make no claims for matching up with drawings etc. All I claim is that it looks a hell of a lot better and cost me almost nothing.

1) The window line.

- easily sorted, just stick a strip of plasticard on the inside, slap on some milliput to fill the holes from the outside, and sand down. Use window decals placed higher up.

2) The Winglets.

Revells winglets are way too short and stubby, but easily corrected. I nipped off the top of each one to give a firm joining surface. then cut a strip of 20 thou platicard about one and a half inches ling. Taking my scalpel I then rough formed it to an airfoil shape by scraping along both sides of the leading edge, and then both sides of the trailing edge. It doesn't have to be too accurate at this stage, it is just to reduce the amount of sanding needed later.

Then cut no more than about half an inch of the strip off at an angle to match the Revell winglet, and glue it on with cyano. I used 'zip kicker' accelerator to instantly harden the joint. I've only been using this stuff for about a year, but it was a real eye opener to me. You get instant super strong joints that almost never break. You can start sanding the winglet extension to shape straight away.

Left, modified but not yet sanded, Right kit part and strip yet to be added.

Winglet1.jpg

Sanded to shape. I did the leading edge/top last of all once the airfoil section was done;

Winglet2.jpg

how it looks;

Winglet3.jpg

3) The Engines.

There are 2 ways of going about this, the method I used and one that Dave Swindell posted as an alternative. I'll post both so you can follow which ever suits you best.

My method;

I started with some thick plasticard & used my Black & Decker to drill a 10mm hole in it (yes really!). I'm not sure what thickness it is but guess at about 40 thou. Then I cut around the hole about 3-4 mm away leaving me with a rough looking ring. I made 2.

These were the glued with plastic weld to the assembled engines (minus the kit intake rings), as was a roughly shaped chunk of 20 thou on the underside. All was left 24 hours to dry.

Cfm-56a.jpg

Using wet and dry sanding paper wrapped around a dowel, I then smoothed and blended the inside of the ring. I first used a coarser grit and then a fine one. Then I improved the outside shape of the ring by sanding, but only to about 80% of the final shape. Next step was to plaster on some Milliput on the underside, leave it 24 hours, then get busy with sandpaper. I srcibed the main panel lines around the new underside with a needle to connect up with the existing panel lines.

Cfm-56b.jpg

Finally, they were sprayed with Halfords primer, then appliance white, and detail painting for the rim etc.

heres how it all looks on the taped together kit;

Cfm-56c.jpg

Cfm-56e.jpg

Cfm-56d.jpg

Cfm-56f.jpg

engine2.jpg

Heres my unmodified engines on the Haribo 737; with the new ones;

cfm56-1.jpg

cfm56-2.jpg

I later went back and sanded a little more 'flat' to the underside, as some flat should still exist as Dave pointed out. See photos of finished model below.

Daves method

The first step is to make a tube of thin plastic card the same diameter as the fan face and slightly deeper than the fan depth in the nacelle. This is glued over the fan face with the join at the top where it is less noticeable. Whilst this is drying tape the two nacelle halves together and file and sand the bottom inside of the inlet to make it rounder. Next assemble the nacelle except for the intake ring, gently squeezing the halves together should make the intake tube conform to the nacelle front shape. When dry trim off the excess tube flush with the nacelle front. Now take the intake ring and with some support from a pen or similar the triangular shape can be gently teased into a more rounded shape. Test fit against the nacelle until the interior shape matches the intake tube, then attach. This will leave a lip on the outside at the bottom, glue sheet plasticard onto the bottom of the nacelle to cover the flat area. This is then filed back to fair it in. Remove some of the plastic from the nacelle sides at the bottom to create a more rounded shape. Repeat for the other nacelle, taking care to ensure they match. This may sound awkward, but it is harder to describe than it is to actually do. Even if you don’t reshape the nacelle, fitting the intake tube will improve the look no end.

Nacellemod1.jpg

Modified nacelle parts on the left, original kit parts on the right

Nacellemod2.jpg

Completed modified nacelle on the left, assembling modified parts on the right

Nacellemod3.jpg

Readytopaint.jpg

Thanks Dave!

STOP PRESS! RICHW has just come up with 3rd method!

Rich's method

The finished model.

A few shots of my completed model, showing how much better all the mods make the kit look;

engine3.jpg

engine4.jpg

Norwegian1.jpg

Norwegian2.jpg

None of this is that difficult to do but makes a huge difference to the model. I'd think Daves method might be easiest for the engines, I'm going to have a go with it on my next 737.

[Edited for small update 19/08/2011]

I've started another 737-800 and though this lttle tip might help. Fitting the wing to the fuselage can be troublesome as the main wheel bay catches on the fuselage opening. On the above model I made this mod, and have done it again on my next build today, but took a couple of pictures. On the left is the unmodified part, on the right how it looks after a bit of sanding & cutting. Basically all you have to do is sand the sharp edge off the rear of the wheel bay, and cut a couple of notches in the rear corners. When it is glued onto the lower wing, the whole wing unit fits into the fuselage much easier after doing this.

737-19.png

[end of edit]

Happy Modelling,

John & Dave.

Edited by Viking
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Now I am going to pull my 737 apart thats nearly done to fix the engines!

Thanks.

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brilliant :)

I have just one 737NG with no power.....coz I've never figured out how to fix the engines....until now

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Hello,

This is an excellent topic, and I will definately use your tips. Well documented, explained and illustrated. And that is so great introducing 3 different methods for engine intake correction.

If you allow me, may I had just for the list another issue with the Revell B737-800. (I had started writing NG series : why they never altered their mould to release different fuselage versions as they did with thieir A-32X series and as Daco/skyline dis with their B737-300/400/500s).

Well may I add that they reversed (upside down) the stabilators airfoil section. I am currently building one Revell B737-800 and I am blocked at this point.

Cheers

Eric B.

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To be fair the engine intake on the 738 isn't completely round and there's still a distinct flattening to the underside of the nacelle. The flattening of the intake lip on the kit parts is clearly overdone, but to me it seems somewhere in between the NG and the Classic.

http://www.airliners.net/photo/Ryanair/Boeing-737-8AS/1701179/L/&sid=175ff2613f7804c1dd5a162f16e095a2

http://www.airliners.net/photo/American-Airlines/Boeing-737-823/1736555/L/&sid=175ff2613f7804c1dd5a162f16e095a2

Good advice to adding some intake trunking though.

Just my :2c:...

Andrew

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Since two of the three NGs I'm working on has winglets, I've been trying to modify the kit parts. I did not have the exact dimensions, so I guesstimated.

What do you guys think?

13745383515_14d4a7c333_c.jpg

One more thing worth correcting is the exhaust opening of the hot section. (Nacelle halves are only dry fitted.)

13745404183_40ec820562_c.jpg

13745407823_c9f4980db6_c.jpg

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Thank you very much for posting this help topic - I have this kit and was thinking about investing in some corrective resin parts prior to reading this post - that's about £25 you have just saved me ...

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A friend of mine who works for Ryanair was kind enough to measure the winglet of a real 738. Here's a winglet I modified based on the measurements he provided.

15370622682_66190e7282_c.jpg

My previous ones were way too big.

I hope this helps.

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A friend of mine who works for Ryanair was kind enough to measure the winglet of a real 738. Here's a winglet I modified based on the measurements he provided.

....picture removed to avoid quoting photographs.....

My previous ones were way too big.

I hope this helps.

To drag this on a bit, recently I set about starting another Revell 737 using a couple of aftermarket sets I've bought: Authentic Airliners 737NG enhancement set and Braz models 737 engines.

I noticed something curious - the Revell winglets have been stated as being the wrong shape and too small...however laid next to the (assumed to be very accurate and correct) Authentic Airliners winglets they're the same size...wrong shape yes, but the same height.

I reshaped a set of Revells winglets few years ago and thought they looked acceptable but not having the correct measurements of the real ones and believing they were too short I think I convinced myself they were wrong.

But now I'm thinking they're actually ok.

Jeff

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This site says 8' 2" base to tip. That's 2494.1 mm. In /144 that becomes 17.32 mm. The Revell kit winglets are about 15mm tall. I'd say to trust your Ryanair friend. He's got the 1/1 thing to measure.

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Here's a drawing my "Ryanair friend" sent me along with a dozen photos explaining where and how he took the measurements. I think it's pretty accurate.

18691304666_2960b3424f_b.jpg

BTW he's also an airliner modeler.

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Ok. Thanks for the replies. I do believe your friend accurately measured the actual winglets so that's not what I'm questioning.

Having measured the RV winglets from the very aft tip to the base where it begins to curve, I've measured it at 15.9mm. The AA winglets measure out to the same size. So do we have a replacement set that is still slightly undersize? Correct shape but not tall enough?

Anyway, I'll reshape the kit parts and use the AA parts, so this is just an observation post really.

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Re the engines - the Revell A319 and A320 kits come with a choice of CFM56-5B or IAE V2500 engines, and are a possible source of spare CFM56 engines.

The Boeing 737-800 uses CFM56-7Bs, but they are close enough visually I think.

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The engines themselves might be, but the cowlings are very different. An airbus cowling on a 737 would scrape the ground.

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Re the engines - the Revell A319 and A320 kits come with a choice of CFM56-5B or IAE V2500 engines, and are a possible source of spare CFM56 engines.

The Boeing 737-800 uses CFM56-7Bs, but they are close enough visually I think.

Er, I don't think so:

Airbus

Boeing

Sorry to disagree but there are really only two ways to go at the 738 engines - modify the kit parts or buy aftermarket items.

Ok. Thanks for the replies. I do believe your friend accurately measured the actual winglets so that's not what I'm questioning.

Having measured the RV winglets from the very aft tip to the base where it begins to curve, I've measured it at 15.9mm. The AA winglets measure out to the same size. So do we have a replacement set that is still slightly undersize? Correct shape but not tall enough?

Anyway, I'll reshape the kit parts and use the AA parts, so this is just an observation post really.

For what it's worth when I did my 737-900 conversion I modified the kit winglets to match AA's dimensions. There must be some kind of scale visual effect in play because I've seen some models where the winglets look too big even though they're supposedly correct dimensionally. The 739 winglets may be a little short but on the model they give a reasonable impression of the real thing, at least to my eyes, although I suppose I would say that!

Edited by Skodadriver

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Okay, I'm suitably convinced about the engines!

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I think there must be some kind of scale effect because I've noted that too - correctly sized winglets and they look quite 'off'.

I just find it curious that a replacement set is correctly shaped but the same size when measurements and references seem to imply they should be taller.

Anyway, as I said I'll continue to use up my AA sets and reshape the kit parts. I can live with that and after all it's really only me who looks at my models!!

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I have to agree. Even though I used the correct measurements, my winglets look a bit too tall on the model. I'm not going to reshape them now, because they are very fragile.

Edited by N5016R

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Nice to see that this post is still provoking useful discussion!

For what it is worth, I think the Revell winglets out of the box are much undersized and benefit from lengthening.
If I remember correctly, I used the decal sheet from the Lima November's Norwegian 737-800. Decals are provided for both Revell sized and correct sized winglets. I photocopied the correct ones and used them as patterns to establish the correct size for my extensions so they would fit.

In the end it comes down to what you are happy with.

In a related note, I have been building an Airfix 737-200 and decided to fix its engines.
All I knew was that they are too short and have too skinny pylons for all but the very earliest 737's built. Everyone on the web seems to have an opinion, but no other solution than to buy a set of Authentic Airliners resin replacements. So I though I would have a go myself, I have several of the kits and can't justify buying loads of aftermarket engines for them all.

Using my Authentic Airliners model as a reference I cut the rear part off and used an old bomb to lengthen them by about 4mm. Milliput was then run around the 'extension' and sanded flush.

Engine1_zpsvweeqomw.jpg

So far so good.Is the extension the correct length? Compared to the AA kit;

Engine2_zpsyppuvtrf.jpg

Then I needed to fatten the pylons. Some 20 thou plasticard takes care of that
Engine3_zps18eahpub.jpg

Filled with Milliput and sanded to shape;
Engine4_zpskte6ijbj.jpg

Engine5_zpsdwahusux.jpg

Test fitted to check overall appearance

Engine6_zpsklc32eny.jpg

Engine7_zpshmtwenyn.jpg

As you may notice, I have also had a look at improving the cockpit using a clear part from a Daco/Skyine kit.

The good news is that it fits beautifully after cutting its shape out of the Airfix fuselage. (Noting in the above photo is glued, it is all dry fitted)

I then decided to scratch build wheel wells and a cockpit. And as I had an Airwaves etched set of Galleys, decided to add them into the mix.

Engine12_zpsgffrhrsm.jpg

Might as well put some crew in. And the first couple of rows of seats can be seen through the open door..

Engine11_zpsoqhdiinq.jpg

Engine9_zps0a7cjpgk.jpg

Engine10_zpsajvuxwfz.jpg

Neither the fuselage or clear part on glued together yet. I'm hopeful that this is going to look pretty effective when finished.

Engines are now primed with Halfords grey plastic primer, ready to go on the model.

Engine13_zpsac5ns6mk.png

Cheers

John

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That's great work John. The engines look a lot better with the extension and pylon widening. I think its detailed somewhere else on this forum that the Airfix engines are 4mm too short. It's good to see the Daco cockpit fits so well too, I may need to invest in a few cockpit sets Danny had moulded as extras to the current production run. Plus you've also saved me from spending a load of money on the AA replacement parts. The extension I can do, I may struggle with the pylon reshaping but I'll give it a go. Thanks.

I received 8a decals for the new Southwest colour scheme and Jon has provided winglet decals that are applied to the kit winglets (I think, I only got then last night and didn't really have time to study them closely) and then sanded down to the shape of the applied decal. That's a good idea. But decals appear to be longer than the Revell winglets, so it's still confusing. I also have LN Decals for the Cimber and Primera 737 schemes. In one if the instruction sheets, mention is made of the new AA enhancement set and the winglets should be used form that to replace the undersized kit ones. However, from what I've seen they're the same size....confused, baffled and bemused!!!!

As has been said, each to their own with what they're happiest with.

Edited by pinky coffeeboat

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