PMN1
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Avro Canada Jetliner

Mon Aug 27, 2007 5:17 am

The wiki article on this says it was originally to have two Avons but British government embarrassment following the sale of engines to the Soviet Union forced the designers to use four Derwenst which reduced its attraction to Trans Canada Airlines.

How true is this and how would it have performed with two Avons?
 
Blackbird
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RE: Avro Canada Jetliner

Mon Aug 27, 2007 6:18 am

I assume it's performance would have been somewhat better. The Derwents to my knowledge produced around 10,000 lbs thrust, the Derwents produced 3,600 a piece (7200 per side).

Keep in mind axial flow engines (single spool) idle around 60 percent with the Derwents which were centrifugal flow, idling around 85 percent. In other words, at intermediate power levels the Derwent would have guzzled way more gas.

Still despite this it's power to weight ratio (Derwent Powered C-102) could achieve about the same thrust to weight ratio as a Convair 880 or a B-727-200 at reduced power takeoff settings

Andrea Kent
 
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Jetlagged
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RE: Avro Canada Jetliner

Mon Aug 27, 2007 7:01 pm

Quoting Blackbird (Reply 1):
Keep in mind axial flow engines (single spool) idle around 60 percent with the Derwents which were centrifugal flow, idling around 85 percent. In other words, at intermediate power levels the Derwent would have guzzled way more gas.

Even accepting the figures you give (where did you get the 85% figure from?) the logic does not equate to higher fuel flow at intermediate power (which is above idle by definition). Fuel flow to rpm is not a linear relationship.

Centrifugal compressors are not inherently inefficient, but they do have limited compressor pressure ratio compared to axial flow compressors which limits their thermal efficiency. An axial flow compressor at the same pressure ratio will be no more efficient, more or less. Centrifugal compressors are still used where lower pressure ratios are acceptable. They are very robust compared to axial designs.
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ptrjong
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RE: Avro Canada Jetliner

Mon Aug 27, 2007 7:25 pm

Quoting PMN1 (Thread starter):
it was originally to have two Avons but British government embarrassment following the sale of engines to the Soviet Union forced the designers to use four Derwents

Selling the Nene to the whole world, then deny it to civilian use makes no sense to me, although that doesn't mean it's not true.

The Early Jetliners volume in The Illustrated International Aircraft Guide makes no mention of this. It does say that 'Avro always intended replacing [the Derwent] when possible with a newer engine. Its own Orenda, a modern axial used in the CF-100 fighter, was well suited to the Jetliner, but this would have made it a twin and 30 years ago airline presidents wanted four engines.

Peter Smile
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Jetlagged
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RE: Avro Canada Jetliner

Tue Aug 28, 2007 1:47 am

I don't think the British government would have had a problem with selling axial flow engines to Canada. They were happy enough to license jet engines for production by the USA. Canada shares the same head of state as the UK, so we are usually friends.  Wink

At the time the Nenes were supplied to the USSR they were still officially allies, though it was in hindsight a very dumb thing to do.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
PMN1
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RE: Avro Canada Jetliner

Tue Aug 28, 2007 9:40 pm

I have got to admit, i did think it was a bit starnge about not selling the Canada and i've not seen that mentioned elsewhere but who know with politics???

 Yeah sure

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