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kitplane01
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KC-390 Engine Choice

Sun Jul 17, 2016 8:05 am

The KC-390, which began design studies in 2006, chose V2500 engines. The CS-100/CS-300, which had design studies start in 2004, chose the P&W Geared Turbo Fan. My question is, why would anyone chose the V2500 as their sole engine choice? Bombardier had enough data to chose the better engine. Why didn't Embraer for the KC-390?
 
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SQ22
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Re: KC-390 Engine Choice

Sun Jul 17, 2016 8:25 am

The KC-390 is a military plane. For a military plane reliability is more important than state of the art = latest technology, hence a different engine selection compared to C Series.
 
TheF15Ace
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Re: KC-390 Engine Choice

Sun Jul 17, 2016 3:05 pm

The size of engine might also be a factor. The much larger GTF might be more difficult to mount on a ''high wing''.

A large diameter fan probably isn't good for takeoff and landing on unpaved surfaces either.
 
L-188
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Re: KC-390 Engine Choice

Mon Jul 18, 2016 9:05 pm

SQ22 wrote:
The KC-390 is a military plane. For a military plane reliability is more important than state of the art = latest technology, hence a different engine selection compared to C Series.


I think you called it right there.

Large parts supply, worldwide support, reliable service for years to work the bugs out.
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
 
prebennorholm
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Re: KC-390 Engine Choice

Tue Jul 19, 2016 1:01 am

Price is likely an important factor. The V2500 is likely considerable cheaper than the PW1000.

Military planes typically don't fly every day all day long as airliners do. Therefore it takes much longer time to make fuel savings match the higher engine price, and maybe it never happens so.

If we imagine that KC-390s will fly on average one hour per day, then with rough geustimates and jumping fuel prices it could take anything between 20 and 100 years to have the PW1000 save the fuel to pay for the higher engine price. While on a well utilized CS100 the breakeven point is more like 2 or 3 years.

The PW1000 is also considerably heavier. That means that over short distances the KC-390 can haul a correspondingly heavier load with V2500 engines.
Always keep your number of landings equal to your number of take-offs
 
strfyr51
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Re: KC-390 Engine Choice

Tue Jul 19, 2016 5:01 am

The V2500 is also a "proven" engine with a LOT of hours in service the PW1000 is actually Not a "proven: engine with worldwide Service.
Kind of like the T39 Vs the CF-6 on the C5 airframe
 
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kitplane01
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Re: KC-390 Engine Choice

Thu Jul 21, 2016 6:01 am

SQ22 wrote:
The KC-390 is a military plane. For a military plane reliability is more important than state of the art = latest technology, hence a different engine selection compared to C Series.


That seems very unlikely. Boeing and Airbus and Bombardier would *not* tolerate an unreliable engine. Neither would the FAA. By any reasonable measure, all these engines are very reliable.
 
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kitplane01
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Re: KC-390 Engine Choice

Thu Jul 21, 2016 6:03 am

prebennorholm wrote:
Price is likely an important factor. The V2500 is likely considerable cheaper than the PW1000.

Military planes typically don't fly every day all day long as airliners do. Therefore it takes much longer time to make fuel savings match the higher engine price, and maybe it never happens so.

If we imagine that KC-390s will fly on average one hour per day, then with rough geustimates and jumping fuel prices it could take anything between 20 and 100 years to have the PW1000 save the fuel to pay for the higher engine price. While on a well utilized CS100 the breakeven point is more like 2 or 3 years.


That could make sense. Do we know if the PW1000 actually costs much more than a V2500 (or seemed likely to cost more ten years ago)?
 
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kitplane01
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Re: KC-390 Engine Choice

Thu Jul 21, 2016 6:17 am

prebennorholm wrote:

The PW1000 is also considerably heavier. That means that over short distances the KC-390 can haul a correspondingly heavier load with V2500 engines.


A 31,500 lb thrust V2500 weighs 2,484 kg (wikpedia) and a pair burns about 3,000 kg of fuel per hour at cruise speed and altitude (internet). The internet does not know what a PW1000G weighs, but a LEAP-1A weighs about 3050 kg. A LEAP-1A or PW1000G burns 15% less fuel, which is a savings of 450 kg per hour. So the breakeven point is at 2.66 hours of cruise flight. After that you get more payload with the more modern engines.

http://booksite.elsevier.com/9780340741 ... efault.htm
https://en.wikipedia.org/wiki/IAE_V2500

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