How to fix these gaps?

There's lots of options.  I like Tamiya white putty but what I've been using lately is Perfect Plastic Putty.  

Deluxe Materiels Perfect Plastic Putty, YouTube Tutorial here

You can also use Bondo spot putty from the auto parts store.

Don't be surprised if it shrinks a bit while you get used to the proper thickness to lay it on.

Also, if you have access to Evergreen Sheet Styrene, you may have good results from filling gaps with a thin strip of plastic, leaving you with a much smaller gap to be filled with putty.

God luck
Rick

Your probably going to get several great responses on this subject.  This site is great for these kinda things.  I've been modeling for less than two years so take this for what it's worth.  I would make sure the two surfaces are even before filling.  
What kit is this?  It's no fault of yours but it looks like the panel lines don't match up.

Surface_Line

You can also use Bondo spot putty from the auto parts store.

Don't be surprised if it shrinks a bit while you get used to the proper thickness to lay it on.

Also, if you have access to Evergreen Sheet Styrene, you may have good results from filling gaps with a thin strip of plastic, leaving you with a much smaller gap to be filled with putty.

God luck
Rick 

I'm with Rick on this.  I've used Bondo spot putty (glazng putty) for decades with great results.  The plus being that it wet sands beautifully.  Only con is a bit of shrinkage but you can re-glaze the next day and sand it to a seam free finish.

For a gap that size, I would end up using either Milliput or Apoxie Clay.  Both are extremely easy to work with and can be smoothed to match the contours of the model with a q-tip dampened with water.  They are water soluble before they cure, but unlike other water soluble putties, once they cure, you don't have to worry about water damaging or removing them.  No sanding...no shrinkage...no dust all over the place...just a smooth joint that is ready for primer and paint.  For smaller gaps, my go-to is plain old Gorilla Super Glue with the blue cap.  No putty, sand, repeat (with more dust) routine with that either.

Not knowing for sure what you're dealing with, or how you're cementing things together,  you might also try the technique in this video that uses Tamiya Extra Thin.  I've never looked back since trying that technique myself.  It lets you slowly close a joint and can even bring poorly-fitting parts into near-perfect alignment.  

Surface_Line

You can also use Bondo spot putty from the auto parts store.

Don't be surprised if it shrinks a bit while you get used to the proper thickness to lay it on.

Also, if you have access to Evergreen Sheet Styrene, you may have good results from filling gaps with a thin strip of plastic, leaving you with a much smaller gap to be filled with putty.

God luck
Rick

 

There are many brands of spot putty, though many brands now call it glazing putty. Auto parts stores and some hardware stores carry it.  I have been using the 3M brand.

It comes in much bigger tubes than model brands, so you must be dilligent about putting cap back on.  while the price per tube is higer than modeller brands, the price per ounce is lower.

castelnuovo

As it happened, it just didn't fit. How do I fix it? I read somewhere that some modelers use some kind of putty to fill the gap. Is it some special putty or can I just go to a hardware store for it? Any other solutions?

Thanks 

Besides putty, or scraps of styrene sheet, you could also take some of the kit sprue and stretch it over a candle flame, then lay it in that gap and flow some liquid styrene cement over it.

Did you test-fit, before assembling?  That can help avoid surprises by revealing areas that don't fit.

That looks like either the Hasegawa or Accurate Miniatures SBD, which should be relatively free of fit issues, at least along the wing root.

Once you get the gap filled, you'll probably need to sand the filler out.  It would be a good idea to lay some masking tape down along the filled area before sanding, to preserve the surrounding detail.

Hi;

      What I do when building a plane with an upper and lower wing pieces is this. I glue ( Spot) the wing root area together after DRY fitting. Then if I have a problem I make adjustments with the wing thickness or shape. Sometimes you just have to use putty. I prefer Testors brand over the others.

        Now here's something I have never seen mentioned.Sometimes the Wing Root area on the fuselage is the culprit, NOT, the wing! You see when the part is extracted from the mold it swells a little and in that area it creates an overage right at the edge, So if the wing dry fits together properly then the fillet area could be to blame. 

         What to do? When you do planes with wing fillets, Modern or old, Look at the wing root area at the fillet on the half of the fuselage looking toward the tail. If the fillet seems to rise at the edge, there's your culprit.

        Sand the edge down with a round sanding stick or a rolled piece of sandpaper slightly bigger that the curve of the fillet. When you get your surface match and still have a gap, It's filler or sprue glue( Very Thick) time.

Easiest method, spread Perfect Plastic Putty along the seam using a thin piece of plastic sheet as a small spatula. Let dry for at least 30 minutes then use a water damp qtip to wipe and clean up. No sanding required, fast simple and efficient.

Further on the styrene idea: take a thin sheet, 0.010 if you have it.

Cut a rectangle about 1" square.

Slip it in edgewise. Wick in thin glue.

Trim as close to the surface as you feel comfortable, then sand to finish.

Another thing I often do is to glue the wing top halves to the fuselage, lining the surfaces up with care.

Then glue the bottom half or halves on. You'll get minor misalignment around the edges but it is not difficult to either fix, or if not a contest model, ignore on the bottom.

Bill

Thank you all, some great ideas here. Wpwar11, it is Academy Douglas SBD-2 Dountless in 1/48.

Here is the method I use and if you want to keep things really clean then use masking tape and run the damp q tip along to smooth and clean things out.

Tape removed leaving a perfect repair. No sandin, quick and easy.

Junkie,

That method looks good.  Does the PPP shrink needing another application?

No shrinking at all.

sprue goo , can be handy in some of these instances .

I totaly suck whene it comes to using plastic putty wish i could get better.  I like to use my sprues as filler just heat and stretch apply and sand.

Cafguy

I totaly suck whene it comes to using plastic putty wish i could get better.  I like to use my sprues as filler just heat and stretch apply and sand. 

I wouldn't worry about it.  If using sprue works for you, there's no reason for you to change what you're doing.

Well;

  Really thick Sproo-Gloo can work. After all, It is plastic. So after checking, using my method of checking for a rise, then Clamp the top of the Wing tightly to the fuselage and then use two applications of Regular glue. As it sets it will squeeze out a wee bit. Sand and, Bob's yer Uncle!

Hi;

     Besides the answer I already posted. (Your photo didn't come up that time) Looking carefully in the gloss the glue created in the light, You had that dreaded gully caused by the " Fat Lip". I would just sand till its gone and see how much crack is left. Then fill it with THICK Sproo-Gloo!

    Use the Thin sanding stick on the edge toward the wing and concentrate on that area. Before the Sproo-Gloo!

What one needs to remember is that each application may require a different method to correct the defects. For example, sprue glue is great when closing a fuselage to get rid of the join line specially if gaps or steps  are present or filling in scratches where re scribing will be needed. Re scribing over putties usually is a problem, cracking and unable to get a uniform scribed line but with SG it’s perfect since it’s melted plastic.  I too also use stretched sprue as a filler agent. Gaps as in the one I pictured PPP is perfect requiring no sanding so no loss of delicate detail there. It’s good to have different tricks in your arsenal .