If you would like I can see if I can get a real picture of the engine from RR I think we still have one in the heritage museum though I'm not sure, but I will check anyway, the dart engine looks pretty accurate but the HP blades look off slightly.
I may have flown on one of those in 1982 or '83. I flew on a Mitsubishi(?) turbo prop from Oahu to Maui on a small inter island airline. The "YS-11" sparked a memory. It was that lay-out.
I thought it was really cool.
Of course, it looks looks we had one at the museum 6 months ago but I will find one at a museum somewhere and help you. I swear it on Queen and Country. You have my word.
You are looking for a Rolls-Royce Barnoldswick (a factory in the United Kingdom) .53 - RB.53 I can suggest looking at the RR Derwent, Avon and Olympus as case studies as well as the RB.162, RB.44, and RB.145.
It may be in your best interest to loo at the RB211 as the the first 3 shaft jet engine although its a turbo prop it still operates is roughly the same way; suck squeeze bang burn, except it has a bypass on it. Look through the different kinds of engines produce by Rolls Royce, if you would like I can share an app to a 3 shaft engine app which we used for STEM activities.
Thanks everyone for many warm comments!
My next project will be the J7W1 Shinden as I am struggling with modelling a Mitsubishi A20 experimental engine now as this was a prototype for J7W1.