tag:blogger.com,1999:blog-5848437078181345610.post1007435839724477140..comments2024-03-08T16:42:41.614-08:00Comments on Tailhook Topics: J79 Exhaust NozzlesTailspinhttp://www.blogger.com/profile/17837863895661437038noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-5848437078181345610.post-81754502380602054852017-09-23T08:19:10.657-07:002017-09-23T08:19:10.657-07:00HI
INSIDE DIAMETER OF THE VARIABLE NOZZLE BOTH OPE...HI<br />INSIDE DIAMETER OF THE VARIABLE NOZZLE BOTH OPEN FULL REHEAT AND CLOSED<br />ON THE j79 FOR A SCHOOL PROJECTAnonymoushttps://www.blogger.com/profile/13094785269246974773noreply@blogger.comtag:blogger.com,1999:blog-5848437078181345610.post-19668442018784402032014-12-08T21:11:20.075-08:002014-12-08T21:11:20.075-08:00Just a little addition to the comment from above a...Just a little addition to the comment from above about the closed nozzle position: "However, the nozzle was only in this position when the engine was running and not in afterburner.". The -10's that I worked on in the RA5C had 4 stages of AB, primary core, primary annulus, secondary core and secondary annulus. When you went around the horn(military stop) the engine would go in to the first stage, primary core and the nozzle would still be mostly closed, as you pushed the throttle further forward you would increase thru the stages to full AB, stage 4 and the nozzles would be pretty far open, all controlled by EGT. At least that is what we, the ADJ's would attempt to adjust and trim to. In combat, especially when taking the PBDA (Post Bomb Damage Assessment) photos the pilots would go into stage 1 AB to eliminate the smoke trail which made it harder for the gunners to track them. I still remember the sweet smell of ionized air working aft of the island during the pre-dawn launch when a J-79 went into full AB against the blast deflectors. (at full AB the aircraft would also be burning about 3 gallons of full per second) Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5848437078181345610.post-6768987867799016172014-02-04T07:35:45.310-08:002014-02-04T07:35:45.310-08:00Ref the -10/17 nozzle interior photo, just discern...Ref the -10/17 nozzle interior photo, just discernable are slots in the sealing flaps inner surfaces. They show more clearly in this Hellenic Modellers photo<br />http://www.helmo.gr/index.php?option=com_deeppockets&task=catContShow&cat=31&id=1545&Itemid=36<br /><br />Of note is that the circumferential slots will still be partially open at cruise whereas the pairs of longitudinal slots are closed completely. Thanks to SAE680295 we know that this 'ventilated seal' arrangement at AB nozzle positions on the -17 nozzle had its origins in similar features to prevent instability in the J79-5 nozzle (B58). The circum slots and 'ventilated seals' also provided the necessary secondary bypass flow - higher at high supersonic flight speeds.<br />More details on this instability phenomenon and its ventilated slot solution can be found in this GE Patent<br />http://www.google.com/patents/US3041825Petehttps://www.blogger.com/profile/17043438950820285317noreply@blogger.comtag:blogger.com,1999:blog-5848437078181345610.post-51715049198110609942014-01-16T10:06:59.966-08:002014-01-16T10:06:59.966-08:00I meant also to add that the information in the p...I meant also to add that the information in the paper makes it great value for $25. The superb photos in Tommy's topic are a good complement to the descriptions in the paper.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5848437078181345610.post-64152428222180046052014-01-16T09:27:42.711-08:002014-01-16T09:27:42.711-08:00The development history of the J79 nozzle is told ...The development history of the J79 nozzle is told in SAE680295 "Variable-geometry exhaust nozzles and their effects on airplane performance". It shows the shroud translation on the early nozzle and no translation of the forward hinge on the guided expansion nozzle.<br />It also describes the Low base Drag Nozzle on the B-58 and the fully variable (ie independant primary and secondary area control) on the J93 in the XB-70.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5848437078181345610.post-13132780914972210862014-01-06T09:45:41.641-08:002014-01-06T09:45:41.641-08:00Possibly and it is true that the nozzle will short...Possibly and it is true that the nozzle will shorten slightly when the nozzle closes. But note that the "bottom" of the pedals is lower as indicated by the red line at the bottom of the picture. I don't think that the hinge line of the pedals moves forward (down in this instance) as the nozzle closes.Tailspinhttps://www.blogger.com/profile/17837863895661437038noreply@blogger.comtag:blogger.com,1999:blog-5848437078181345610.post-65340779583150405992014-01-06T09:21:42.068-08:002014-01-06T09:21:42.068-08:00In my opinion regarding the (Picture by John B.) m...In my opinion regarding the (Picture by John B.) most of the difference in nozzle length is due to the left nozzle being more fully closed and the angle of the photo.David Gallowayhttps://www.blogger.com/profile/16403054467527742042noreply@blogger.com