I had a bit of fun over the break, I had a Minicraft PBY kit minus engines (sacrificed for a Sunderland conversion some time ago) and some surplus 1/144 Vickers Viscount parts (including engines).
I remembered seeing this artists impression some time ago of a Dart turbine conversion proposed by Avalon Aviation in Canada (apparently Avalon produced quite a number of conceptual design drawings & some engineering calculations with the idea that they might re-power some of their water bomber fleet.). The idea was to use engines from time-ex Viscount airframes, unfortunately Avalon folded in the late '80s and the project never saw the light of day.
I have tried to bring one of the drawings to life
I will probably have to give it a rego. from one of Avalon's fleet to give it some kind of context
The turbine Cat would be a good way to combat lack of engine spares but - like the unflown Dart Mustang in Australia - perhaps extra fuel tanks would be needed? Or would the Cat already have enough capacity to make it feasible?
Turns out the artwork was featured in the book "PBY: The Catalina Flying Boat" by Roscoe Creed. Info from it: "For some Cansos the future may hold a different look and a different sound. Avalon Aviation is considering planes to replace the reciprocating engines of its Cansos with Rolls Royce Dart turboprop engines, creating a "Turbo Cat" that would outperform even the Super Cats. Because the planes are based on land and scoop their loads from fresh water lakes and rivers, none of the corrosion problems attendant on turbine-powered seaplanes which operated on salt water after the war would be likely."
Last Edit: Jan 21, 2015 8:07:07 GMT 12 by ZacYates
From what I read in David Leggs book, They proposed the Dart owing to its similar weight to the Pratts, modern engines would have put the props too far out from the leading edge to get the correct CoG. pBYs have fuel capacity of 1,750 US gal or over 6,600 L so fuel capacity not really an issue ? That would give a standard PBY about 2,100 mile range.
They proposed the Dart owing to its similar weight to the Pratts, modern engines would have put the props too far out from the leading edge to get the correct CoG.
That certainly makes sense, but there are more issues surrounding the PT-6 being a more sensible choice, such as the fact Darts are no longer in production and therefore spares and maintenance become a serious cost and logistics exercise. There are only a few places in the world that can carry out overhaul on Darts - thankfully we have the capacity here in New Zealand, but the PT-6 is still in production and these issues would not occur. Also, the placing of the Dart puts the props in line with the forward windscreen, just looking at your model, Harry. The PT-6 would probably require the same, look at the Turbo Porter installation, but it would be a more economical choice in the long run, not to mention more reliable.
The Canadair CL-415 is interesting when compared to its piston engined predecessor; its engine nacelles are identical to the Q300 forward of the firewall, with whom it shares the same PW100 series engine. These are a big motor though and put out quite a lot of power.
...However not really an issue these days though as now there are only about 20 potentially airworthy Catalina airframes left in the world and only about 6 of those are regularly flown, things were different in the '80s as the darts were readily available, cheap and spares were still manufactured and Catalinas/Cansos still had value as fire fighting aircraft. Most of these aircraft became idle from the 1990s, some rotted in the elements and others found their way into collections as static display aircraft.
The extra power of the dart turbine conversions might have been interesting though, Bob Dyck (ZK-PBY training captain and former waterbomber pilot) once told me that even the R-2600 re-engined Super Catalinas were over powered. Despite the fact that they could carry extra payload, he alway felt he was chasing the airframe's VNE all the time when operating!
Last Edit: Jan 22, 2015 20:48:10 GMT 12 by harrysone