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Bypass Ratio Of The CJ-805-23 Engine?  
User currently offlineHappy-flier From Canada, joined Dec 1999, 299 posts, RR: 0
Posted (6 years 6 months 6 days 20 hours ago) and read 6840 times:

Anyone know what the bypass ratio was in the rear-fan-stage CJ-805-23 that powered the Convair 990? I have been looking around but could not find this info online.

Interestingly, there are some rare videos on Youtube of a Spantax CV990 in operation in its twilight years. Like most, I had never heard or seen one flying, so it was nice to finally get a chance. Here are some interesting ones:

CV990 landing: http://www.youtube.com/watch?v=ZXl9AgWTb0w
CV990 taxiing in: http://www.youtube.com/watch?v=sPF-bNgpYHk
CV990 taxiing out: http://www.youtube.com/watch?v=ZHN8AfDSCbo
CV990 takeoff: http://www.youtube.com/watch?v=HTlT2-i4gjw

Interesting sound; different than the JT3Ds that were so much more common in those days. Note the wild howl on power-down, just on the landing flare ...


May the wind be always at your back . . . except during takeoff & landing.
5 replies: All unread, jump to last
 
User currently offlineViscount724 From Switzerland, joined Oct 2006, 26005 posts, RR: 22
Reply 1, posted (6 years 6 months 6 days 9 hours ago) and read 6804 times:

Page 29 of the following document shows the bypass ratio of the CJ-805-23B as 1.46.
http://ntrs.nasa.gov/archive/nasa/ca...asa.gov/19770012125_1977012125.pdf

[Edited 2008-06-18 19:07:54]

User currently offlineBlackbird From , joined Dec 1969, posts, RR:
Reply 2, posted (6 years 6 months 6 days 7 hours ago) and read 6790 times:

Viscount724,

Fascinating, I always thought it was 2.2 : 1 as lots of sources listed it as such including a book I own.


Andrea Kent


User currently offlineHappy-flier From Canada, joined Dec 1999, 299 posts, RR: 0
Reply 3, posted (6 years 6 months 5 days 21 hours ago) and read 6762 times:

Thanks for the info. It seems that it was an engine ahead of its time in some ways, although the smoky exhaust was terrible.

They must have done something to modify the core because as you can see in the videos above, the Spantax 990 was actually a pretty clean burning jet - not much smoke at all.



May the wind be always at your back . . . except during takeoff & landing.
User currently offlineBlackbird From , joined Dec 1969, posts, RR:
Reply 4, posted (6 years 6 months 5 days 8 hours ago) and read 6724 times:

Happy-flier,

That's correct they did go to great lengths to reduce the smokiness of the exhaust and apparently succeeded. Not only did this curb the smoke, it increased thrust slightly


Andrea Kent


User currently offlineBoeing767mech From United States of America, joined Dec 2000, 1031 posts, RR: 3
Reply 5, posted (6 years 6 months 4 days 14 hours ago) and read 6681 times:



Quoting Happy-flier (Reply 3):
They must have done something to modify the core because as you can see in the videos above, the Spantax 990 was actually a pretty clean burning jet - not much smoke at all.

The reduced smoke was a result of the miltary wanting to reduce the smoke from the J-79's. GE found by welding some of the cooling holes in the burner can you increase the temp of the flame which reduces the soot. The added bonus was the increase in thrust. My friend was a crew chief on a f-4 that had one engine with a ashless can and a regular engine, he said it was interesting to see on finally appoarch.

David



Never under-estimate the predictably of stupidty
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