Having undercoated and painted the undersides of my Sopwith Triplanes I've had to decide on a paint scheme for them. Despite there not being a lot of choice with British planes they can sure give you a headache! :-)
The RNAS were the primary users of the Sopwith Triplane and the most famous users the legendary Black Flight of No. 10 Naval Squadron. As you can see from the picture below quite a simple but neat scheme with distinctive black cowlings and wheels...
But as ever ascertaining the fuselage colour is a problem. RFC planes are generally painted PC10 which can be reasonably portrayed with either GW Catachan Green or Tamiya NATO Green (the shade does vary due to the mix, field service conditions and weathering).
RNAS planes are normally painted PC12 and this is a contentious subject of much debate. Is it a chocolate brown, a red brown, a more earthy brown? Who knows, the situation is further confused with new late war colours used in the tropics being mistakenly identified as PC12 on fabric samples.
"Popular opinion" suggests that Tamiya's Flat Earth or Flat Brown are the best colours for PC12 but one post I read about the IWM RNAS Camel is that the colour can vary from green to brown depending on the angle viewed at! Also, the picture above looks like Catachan Green to me! :-)