AB139 vs S76D Comparison

[Cyclone7]

Anybody out there done a comparison study between these 2 models?

[spinwing]

Mmmmm ...

Why ... they are both in different leagues ... the 139 is out there flying productively and the 76D's 'real' performance is yet to be assessed.

Be a bit like comparing Apples with Oranges would it not?

[SansAnhedral]

well, here is the S76D versus the C++ :E

http://www.flightglobal.com/Assets/GetAsset.aspx?ItemID=44192

from FLIGHT TEST: Sikorsky S-76D (http://www.flightglobal.com/news/articles/flight-test-sikorsky-s-76d-367864/)

[tistisnot]

Apples with oranges?? Try feet with knots!

[Soave_Pilot]

well, here is the S76D versus the C++

Cant see where the improvement on the 76D is at? Only the extra few miles range and couple of knots, anything else besides that?

[misterbonkers]

Soave - I thought exactly the same but if you read the article there seems to be a lot of improvements not list in the comparison above.

[SansAnhedral]

I thought exactly the same but if you read the article there seems to be a lot of improvements not list in the comparison above.

Purchase price notwithstanding

[ShyTorque]

Seems to me Sikorsky got caught on the hind leg with this one. Too little, too late. They only seemed to get going with this D model once they had lost the military Commanche project (the latter being a terrible loss for the industry, imho).

Unless they can get the MAUM increased, they will always be behind the pack leader.

Rather than a "D" model, on paper it appears to be more of a "C-" ! :oh:

[Soave_Pilot]

I read the article, from my perspective looks like it's a bit more "computerized" C++. That could be good or bad, depends on how you look at it.

[Hilife]

Engine improvements

Just read the article over a coffee and noted the following comment.....

....the engines upgraded to the more powerful and fuel-efficient Pratt and Whitney PW210S. This burned about 600lb/h on our 8 December test flight. Sikorsky experimental test pilot Greg Barnes, in command for the test flight, says this is typical.

That’s about 50lb/hr less than the S-76C++ and with more fuel onboard, range should surely be increasing, not decreasing.

P&WC claim..... ″The PW210S has been designed to offer the highest power-to-weight ratio and lowest fuel burn in the market, which translates into payload and range benefits for the helicopter.″

Much as this could be construed as just sales bumf, P&WC has an excellent standing in the helicopter industry (take a look at the AIN Product Support Survey these past 10-years) and Pratt must have spent a small fortune these past 6-years’ or so on the PW210 engine, so I find it hard to believe their new generation PW210 series does not promise notable improvements in fuel burn, power, reliability and life cycle costs.

Platform size and output power aside, the PT6C-67C gas generator is a derivative of the PT6A-67 (as used on the Shorts 360-300 and Beech 1900D) and there can be no doubting the outstanding reputation of the venerable and reliable PT6 series, but its design is over 50-years’ old and getting a little long in the tooth if truth be told.

Whereas the PT6C-67C has a 5-stage compressor (yes it’s kicking out more mass flow), the PW210S has just 2 compressor stages and encompasses a VIGV, so technology improvements and lower life cycle costs - let alone huge fuel burn differences - must make the PW210S a much more economical engine to operate.

[RVDT]

S-76D

OEI Shaft horsepower (30 sec) 1,241 shp 925 kw

OEI Service Ceiling 7,550 ft 2,301 m

Add a couple of thousand feet to IGE and OGE hover performance over C++ as well.

[terminus mos]

The 139 has FAA type certification while the other is still "expecting" FAA type certification which was originally expected in 2009?

[HeliTester]

OEI Shaft horsepower (30 sec) 1,241 shp 925 kw

1,241 shp sounds great, but I think the 30 sec transmission limit is only 1,050 shp, leaving a lot of inaccessible engine power.

[Sir Korsky]

The c++ 30 sec OEI is 136% transmission torque, so that number makes sense.