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AB139 vs S76D Comparison

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AB139 vs S76D Comparison

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Old 30th Jul 2012, 21:11
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AB139 vs S76D Comparison

Anybody out there done a comparison study between these 2 models?
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Old 30th Jul 2012, 21:40
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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?
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Old 30th Jul 2012, 21:41
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well, here is the S76D versus the C++



from FLIGHT TEST: Sikorsky S-76D
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Old 31st Jul 2012, 01:00
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Apples with oranges?? Try feet with knots!
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Old 31st Jul 2012, 14:44
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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?

Last edited by Soave_Pilot; 31st Jul 2012 at 14:46.
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Old 31st Jul 2012, 15:00
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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.
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Old 31st Jul 2012, 17:07
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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
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Old 31st Jul 2012, 23:28
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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-" !
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Old 1st Aug 2012, 01:55
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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.
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Old 2nd Aug 2012, 06:55
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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.
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Old 2nd Aug 2012, 08:41
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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.
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Old 2nd Aug 2012, 23:15
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The 139 has FAA type certification while the other is still "expecting" FAA type certification which was originally expected in 2009?
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Old 4th Aug 2012, 03:56
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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.
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Old 4th Aug 2012, 12:29
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The c++ 30 sec OEI is 136% transmission torque, so that number makes sense.
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