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J-79 Sound?  
User currently offlineAllisonTP From United States of America, joined Sep 2001, 13 posts, RR: 0
Posted (12 years 9 months 1 week 1 day 15 hours ago) and read 2028 times:

Hey everyone,

I recently had the priviledge of seeing 2 F-104 Starfighters at an airshow. These aircraft had a very distinct whining sound when they flew by. I'm pretty sure anyone who has seen these aircraft being demonstrated knows what Im talking about. Is this sound characteristic of the GE J79 or do all single spool turbojets share this?

Thanks,
AllisonTP

7 replies: All unread, jump to last
 
User currently offlineAvt007 From Canada, joined Jul 2000, 2132 posts, RR: 5
Reply 1, posted (12 years 9 months 1 week 1 day 7 hours ago) and read 1963 times:

I grew up on Canadian fighter bases, and I'll always remember the sound of the 104s. In particular, there was a certain rpm on the ground, where the engine made a very distinctive howl, you could hear it for miles!
They are a classic a/c, and I miss them. We haven't seen them in Canada for about 20 years. Where did you see them?


User currently offlineAllisonTP From United States of America, joined Sep 2001, 13 posts, RR: 0
Reply 2, posted (12 years 9 months 1 week 1 day 1 hour ago) and read 1941 times:

Actually, I saw them in Canada as an airshow demonstration team.(CFB North Bay, Ontario.) They also had a CF-100 and F-101 on display! Intersting to note, since North Bay downsized the base, Bombardier worked out a deal to produce the CL-415 waterbomber aircraft in the old hangers, and from what I have head components for their new regional will be manufactured there.


User currently offlineTEDSKI From , joined Dec 1969, posts, RR:
Reply 3, posted (12 years 9 months 6 days 21 hours ago) and read 1916 times:

Nothing can beat the sound of two GE J79s in a McDonnell Douglas F-4 Phantom!

User currently offlineAvt007 From Canada, joined Jul 2000, 2132 posts, RR: 5
Reply 4, posted (12 years 9 months 6 days 6 hours ago) and read 1903 times:

There`s no way to sneak up on someone either, with the smoke trail they leave!

User currently offlineFlightSimFreak From United States of America, joined Oct 2000, 720 posts, RR: 0
Reply 5, posted (12 years 9 months 3 days 15 hours ago) and read 1892 times:

Air and space smithsonian magazene did an article on the "starfighters" display team... when they interviewd the pilots, they mentioned a "howl" RPM setting. The reason this happens is because there's a smaller round thing inside the engine sort of like the one on the outside (if it weren't 2 in the morning here I'de probably call them something that you'de all understand) well, at these specific RPMs the outer part of the engine is on, and the inner is off, thus similarly to blowing over a bottle, that howling sound is made. Tomarrow morning before I go to work, I'll re-read that article and reply again. G'night.

User currently offlineAllisonTP From United States of America, joined Sep 2001, 13 posts, RR: 0
Reply 6, posted (12 years 9 months 3 days 5 hours ago) and read 1887 times:

Now that you have me pointed in the right direction, could you happen to be referring to the primary assembly of the ejector exhaust nozzle? When the engine is producing low amounts of thrust, the inner inner nozzle is constricted and spring loaded doors open due to low pressure gradients, allowing a larger amount of tertiary air into the exhaust stream. It had never occured to me that the increased tertiary air would have been creating that howl. Makes sense wahen you think about it. That sound is no longer heard today because most moden aircraft use iris type nozzles.

User currently offlineTomH From United States of America, joined May 1999, 960 posts, RR: 2
Reply 7, posted (12 years 9 months 2 days 12 hours ago) and read 1882 times:

Allison,

The howling sound is much more pronounced on the F-104 than on any other J-79 powered aircraft. This may be a result of the high speed of the aircraft in the landing pattern resulting in a more noticeable doppler shift. Also, the twin-engine design of the other J-79-powered aircraft (F-4 and A-5) may have affected the "purity" of the howl through inevitable slight RPM mismatch.

My guess is that the engines variable-stators played a large role in producing the sound. I believe this is how GE attained proper airflow control without resorting to a two-spool design. Someone with more knowledge may be able to help out here.

I saw the 4-engine B-58 Hustler fly a couple of times, but I don't recall too much about the sound. I think my either I was concentrating on photography or my jaw was opened in awe, thus affecting my hearing.

Hope to see the Canadian team sometime soon!

TomH



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