tag:blogger.com,1999:blog-10000144.post111981074202599422..comments2024-03-13T09:47:40.487+00:00Comments on Cockpit Conversation: Beta Reverse ValveAviatrixhttp://www.blogger.com/profile/13634111275860140084noreply@blogger.comBlogger13125tag:blogger.com,1999:blog-10000144.post-73081156599774932032009-03-22T10:17:00.000+00:002009-03-22T10:17:00.000+00:00you want to know what happens if beta is engaged w...you want to know what happens if beta is engaged while flying - here you go : <BR/>http://aviation-safety.net/database/record.php?id=20010324-0<BR/><BR/>"The accident appears to result from the Captain's use of the propellers in the reverse beta range, to improve control of his track on short final. A strong thrust asymmetry at the moment when coming out of the reverse beta range would have caused the loss of yaw control, then roll control of the aircraft.PatBatemanhttps://www.blogger.com/profile/11734758177895829183noreply@blogger.comtag:blogger.com,1999:blog-10000144.post-86293573011560732462007-05-21T01:24:00.000+00:002007-05-21T01:24:00.000+00:00I built a blog about valve !Let us talk about valv...I built a blog about valve !<BR/>Let us talk about valve in my blog !<BR/><BR/>http://value2007.blogspot.comlillian wu Shunde polytechnichttps://www.blogger.com/profile/04144850907254848098noreply@blogger.comtag:blogger.com,1999:blog-10000144.post-1123682158717627372005-08-10T13:55:00.000+00:002005-08-10T13:55:00.000+00:00I am writing a paper for my Master Degree and ran ...I am writing a paper for my Master Degree and ran across your conversation. This might help. http://www.airdisaster.com/reports/ntsb/AAR94-06.pdf<BR/>In short, in a Saab 340, the pilot moved the power levers into the Beta range during flight. The propellers and engines experienced extreme overspeed when propeller and engine governing was lost while operating in the beta range. The engines were substantially damaged during the overspeed and necessitated a power-off emergency landing.<BR/>Hope this helps. JimAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-10000144.post-1120684603030760482005-07-06T21:16:00.000+00:002005-07-06T21:16:00.000+00:00Heeeee...they only let me fly those fixed pitched ...Heeeee...they only let me fly those fixed pitched under 200HP planes but I've read enough reviews of PT6 powered doctor killers to know which context of beta you were referring to.<BR/><BR/>I didn't know, however, that alpha was angle of attack and beta blade angle in general. Learn something new every day.dibabearhttps://www.blogger.com/profile/05160261542703053377noreply@blogger.comtag:blogger.com,1999:blog-10000144.post-1120676717414985442005-07-06T19:05:00.000+00:002005-07-06T19:05:00.000+00:00Quite the contrary, anoynmous. Your guess was righ...Quite the contrary, anoynmous. Your guess was right on the mark. So much so that I thought it would be condescending to mention it. Without the beta reverse valve or beta backup valve (coming soon) an underspeed propeller would continue flattening right through zero blade angle to reverse. The beta system stops that from happening.<BR/><BR/>You're right that beta is a term for the angle of the blades, to complement alpha representing the angle of attack, when airflow is taken into consideration. I never before connected that beta to the "beta range" but yeah, it's also caled the beta control range.<BR/><BR/>For this airplane the beta range is defined as the range of operation where the pilot directly controls the blade angle with the power lever.<BR/><BR/>I'm actually very impressed with my readers. I didn't "get" this stuff on first exposure, and I had far more motivation to learn it.Aviatrixhttps://www.blogger.com/profile/13634111275860140084noreply@blogger.comtag:blogger.com,1999:blog-10000144.post-1120624653856867672005-07-06T04:37:00.000+00:002005-07-06T04:37:00.000+00:00A very spectacular crash occurred because a Lockhe...A very spectacular crash occurred because a Lockheed Electra (not used much after this; you'll recognize it as the P-3 Orion Naval anti-submarine warfare aircraft) pilot elected to use a little "reverse" on approach because he was high on the glidepath. The aircraft basically went straight into the ground.<BR/><BR/>On the other hand, a Sabreliner can reverse individual engines in flight with no ill effect (the clamshells can, and do, open inadvertantly).<BR/><BR/>As Aviatrix said, anywhere from catastrophic to nifty. The key is not to experiment. Reverse in PT6 powered aircraft is not approved for use in flight on any installation that I know of. In all cases that I am familiar with it leads to rapid loss of control.Old Blind Doghttps://www.blogger.com/profile/08534693955145315315noreply@blogger.comtag:blogger.com,1999:blog-10000144.post-1120589103648241452005-07-05T18:45:00.000+00:002005-07-05T18:45:00.000+00:001. Beta is not the same as reverse. In the particu...1. Beta is not the same as reverse. In the particular airplane I am describing, beta starts at eleven degrees blade angle, still in the forward range. <BR/><BR/>2. Yes, the result of engaging reverse or beta in flight depends on the aircraft and the phase of flight. It ranges from catastrophic to nifty.<BR/><BR/>3. Remember that beta/reverse on a propeller aircraft is about changing the angle of the propellers while reverse thrust on a jet is about redirecting the exhaust/bypass thrust as it exits.Aviatrixhttps://www.blogger.com/profile/13634111275860140084noreply@blogger.comtag:blogger.com,1999:blog-10000144.post-1120588114153368002005-07-05T18:28:00.001+00:002005-07-05T18:28:00.001+00:00I've been trying to find a good page summarising w...I've been trying to find a good page summarising what would (does?) happen if beta mode is engaged during flight. As I understand it, an accidental thrust reverser deployment on a jet could dismount the engine from it's pylon, or potentially destroy the wing, but the other comments seem to suggest beta-in-flight is a bearable, possibly even practised phenomenon (on some models of aircraft, presumably). Is this really the case?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-10000144.post-1120588113408916602005-07-05T18:28:00.000+00:002005-07-05T18:28:00.000+00:00I've been trying to find a good page summarising w...I've been trying to find a good page summarising what would (does?) happen if beta mode is engaged during flight. As I understand it, an accidental thrust reverser deployment on a jet could dismount the engine from it's pylon, or potentially destroy the wing, but the other comments seem to suggest beta-in-flight is a bearable, possibly even practised phenomenon (on some models of aircraft, presumably). Is this really the case?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-10000144.post-1120580141050959892005-07-05T16:15:00.000+00:002005-07-05T16:15:00.000+00:00We're not alowed to use reverse thrust in our airc...We're not alowed to use reverse thrust in our aircraft, except during landing when it really is required. Beta alone is very effective in the Caravan for short landings.<BR/><BR/>Reverse thrust tends to throw any loose debris on the ramp or runway forward, where it can be sucked into the engine.<BR/><BR/>Using beta in flight is a real gamble. All of the Caravans I've flown have differed widely in how quickly they go from beta to reverse. The saying about old and bold pilots applies here, I think.Avimentorhttps://www.blogger.com/profile/17508862704398151334noreply@blogger.comtag:blogger.com,1999:blog-10000144.post-1120580058175397682005-07-05T16:14:00.000+00:002005-07-05T16:14:00.000+00:00Dang...shoulda said what I was going to last night...Dang...shoulda said what I was going to last night...that the props move into beta.<BR/><BR/>Military pilots can use reverse in flight to perform a tactical landing. I've seen a C-130 touchdown and stop using 500 feet of runway during such a maneuver. Likewise, they've got those fancy JATO bottles for those snappy really short-field take-offs too. :-)dibabearhttps://www.blogger.com/profile/05160261542703053377noreply@blogger.comtag:blogger.com,1999:blog-10000144.post-1120576379358211322005-07-05T15:12:00.000+00:002005-07-05T15:12:00.000+00:00What sweavo said.What sweavo said.Aviatrixhttps://www.blogger.com/profile/13634111275860140084noreply@blogger.comtag:blogger.com,1999:blog-10000144.post-1120554810666906282005-07-05T09:13:00.000+00:002005-07-05T09:13:00.000+00:00So do the props akshully stop befor ereverse thrus...So do the props akshully stop befor ereverse thrust? Or am I missing something?Anonymousnoreply@blogger.com