Austin wrote:kvs can you explain the pros and cons of PD-14 Engine Design Approach versus says the GTF design.
Even the PD-35 engine design has not chosen a GTF approach but relying on PD-14 like approach
For one I read PD-14 will have less maintenance but GTF design has more technology advantages on long run ?
The PD-14 does not have gearing which limits the bypass ratio to under 8.5 compared to the 12 for the P&W PW1000G.
But the fuel penalty is only 2.5% according to one estimate
The gearing issue is obscure. They talk about reliability but gears add complexity and hence reduce reliability
and engine life. I see a deliberate choice by the makers of the PD-14 to not dabble with gears for such a
tiny fuel consumption advantage. The PD-14 use hydrodynamics knowhow to improve efficiency and the use
hollow titanium fan blades, single-crystal turbine blades with cooling is nothing to be scoffed at.
I really do not see this long term technology advantage of GTF. We will see if ceramic turbine blades are deployed
some time in the future in addition to better combustion design through simulation. I think there is enough evidence
to prove that Russian designers know what they are doing.
According to Pitor who is reliable here PW1400G offers 1 % Fuel advantage over PD-14 engine but PD-14 still wins over PW engine due to lower weight and consequently better effeciency. http://bmpd.livejournal.com/2653756.html
Unless that 2.5 % is a long term goal built into engine for GTF type ,then I would say 2.5 % is not something to scoff at , Even 1 % fuel effeciency of Engine over say a period of 25 years of operation would years more money to operators.
I think PD-14 development may not be static , Already there are talks of using Carbon Fibre blades replacing Hollow Titanium ones which might improve fuel effeciency perhaps others are under works.
The choice of airliners is go for more complex higher maintenance PW engine but with slightly better effeciency or go for less complex but lower maintenance PD-14 engine but slightly lower fuel effeciency.
I think in the history of engineering Less Complex Less Moving Parts is better than more complex more moving parts irrespective of the small gains.
PErhaps that is the reason they are keeping the PD-14 approach to engineering design for PD-35 engine and not opting of GTF .....They were toying with GTF idea for PD-18 engine but thats now off the chart.
I hope and pray they continue flight testing program of MS-21 without serious issues and on time. This bird is more technology advanced than any thing its competitor will offer for the next 10 years