Ziroli Plans Sopwith Triplane Modifications

Image from Ziroli Plans website

If it weren't for the Sopwith Triplane, the Fokker Dr.1 would not have existed. There are far too many of the latter around. Nick Ziroli is more known for his WW2 designs, so his WW1 types are more "standoff scale". For the really discerning builder, there are more accurate plans/kits available.


This model is somewhere between 1/4 and 1/5 scale, depending on which dimensions you are looking at. The choice to call it 1/5 scale is one of marketing, I think. To go head to head with other 1/4 scale offerings is probably not a wise decision. However, when one looks more closely at the plans and takes some measurements, it turns out that the model is much closer to 1/4 scale in all but wingspan.


A 1/4 scale Balsa USA Pup, for example, has a 9 inch cowl, whereas this airplane is 9.25". The tail surfaces are almost exactly 1/4 scale. So, why were the wings clipped? It would seem that the reason is to improve flyability under most conditions by keeping the wing tips out of the dirt and making it easier to fly in wind. It is also heavy, at near 20 lbs, when most 1/4 scale models are around 14 or so. The plan shows a G-38 engine and it still needed 2 lbs of weight in the front of the cowl.


For those who want a WW1 type, but don't want to deal with delicate construction and wire rigging, this triplane might be for you and there are some very simple things that can be done to improve the scale accuracy with very little effort. Simply adding 2 rib bays to each wing panel would increase the span of each wing by 12" and bring the aspect ratio up to where it should be, as well as adding a good 300 sq in to the wing area. That by itself would probably be enough. With a little more effort, one could substitute an aluminum cowl from Balsa USA or Mick Reeves and make it work, while maybe being able to remove some nose weight. Going with larger wheels is also an option. The plan calls for the Dubro 5.6" wheels, but one could upgrade to the William's Bros 6-5/8" or the Dubro 7" wheels. Since the landing gear wire needs to be bent anyway, spreading the wheels apart to a 1/4 scale 16.5" ( They are about 13.5" on the plan ) is not a bad idea either.