P 39: Round Red Spots on the wings.

You mean the fuel tank caps?

I can barely read the decals but it seems to be fuel caps.  However, there are 6 fuel caps per wing.  Later only one fuel cap per wing is painted red but a red line is drawn around the rest.  Why would you need twelve fuel caps on an fighter plane?  It's been a few decades but I only remember one refueling point per aircraft in the Navy and that was 40 years after the time of the P39.  Nobody's perfect but if there was more than one I never heard about it when I was pumping.  I have no idea about how many fueling points were on WW2 aircraft in general.  I'm beginning to suspect that the markings are in error.  But I found this:   <a href=legendsintheirowntime.com/.../P39_Av_4402_sk_tanks_p142_W.png>fuel tank</a>

legendsintheirowntime.com/.../P39_Av_4402_sk_tanks_p142_W.png

Sorry, I screwed that one.

Some aircraft have multiple fuel caps on them besides drop tanks. More likely they have fuel cell tanks in sections.

I found an illustration showing three fuel sections in each wing, it didn't come up like I intended.   I'm wondering if some modification later in the war reduced the number of fuel caps needed or was just the markings reworked.  I don't know if the drop tanks were refueled through the caps in the wing or directly The P39 is a interesting build.  In some ways its entrance into the war resembles the P51.  No supercharger to begin with and both planes came into their own in the hands of our allies.

I would say use only one fuel cap marking. You must have the older kit. Later Revell kits don't have that in the instructions. While looking at various other models by different manufacturers, I noticed that models built from their kits have only one fuel cap marked.

Too late, I painted all twelve before getting curious.  I needed the practice, anyway.  Copyrights on this kit are listed as '69, '83, & '89.  It's the Confederate Air Force Ghost Squadron series.  Normally, I don't get caught up in the minutiae of details about an aircraft but I have always had a soft spot for the P39 and for things that don't make sense in general.   The other kits that have only one fuel cap marked, paint  the rest of the caps inboard of that as contained in one set of rectangular lines.  

I've got a cutaway drawing of a P-39 that shows multiple fuel cells in each wing, with fillers for each cell.

Gary

http://www.airvectors.net/avp39.html

Wonder if it's related to the self sealing tanks.