AirTalk.org Aviation discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Aerodynamic qualities by geographic location          AirTalk.org Forum Index -> Planes, gliders and flying in Australia View previous topic :: View next topic   Author Message Non Compis Mentis Guest Posted: Sun Apr 04, 2004 11:49 am    Post subject: Aerodynamic qualities by geographic location Folks, A rhetorical question, but all other things being constant, do aerodynamic qualities of an aircraft change by geographic location? Reason why I ask it is because of the different methods taught of stall recovery of the same a/c type in different countries/schools. e.g. PA28-161 - stall clean: In Aus - Throttle off, release back pressure, flying speed (60KIAS?), apply throttle and climb out.. UK: full throttle, release back pressure but maintain height - when enough a/s, fly away... (at least 2 organisation taught it this way). I know which one I generally prefer, but why the difference for the same a/c type? NCM Back to top Stealth Pilot Guest Posted: Sun Apr 04, 2004 12:58 pm    Post subject: Re: Aerodynamic qualities by geographic location On Sun, 04 Apr 2004 21:49:55 +1000, Non Compis Mentis <ncm (AT) somewhere (DOT) com> wrote: Quote: Folks, A rhetorical question, but all other things being constant, do aerodynamic qualities of an aircraft change by geographic location? Reason why I ask it is because of the different methods taught of stall recovery of the same a/c type in different countries/schools. e.g. PA28-161 - stall clean: In Aus - Throttle off, release back pressure, flying speed (60KIAS?), apply throttle and climb out.. UK: full throttle, release back pressure but maintain height - when enough a/s, fly away... (at least 2 organisation taught it this way). I know which one I generally prefer, but why the difference for the same a/c type? NCM not enough data points for a valid sample. I think your australian example is an anomalous one. the uk procedure is the correct one for recovery from an incipient stall with zero or minimal loss of height. I use it in the tailwind as well. (only exception would be an aircraft such as a P51 with enormous amounts of torque, then you'd bleed in the power gradually.) regulatory differences used to exist but australia has abandoned the local quaintness for the manufacturers original operating instructions. btw there are performance variations actually due to geographic locations though not what you are alluding to. there is a map in the aip's I think which gives standardised figures for density height by season across australia. ground elevation, temperature, density and humidity are the factors. Stealth Pilot Back to top Centurion Guest Posted: Sun Apr 04, 2004 2:55 pm    Post subject: Re: Aerodynamic qualities by geographic location Stealth Pilot wrote: Quote: On Sun, 04 Apr 2004 21:49:55 +1000, Non Compis Mentis [email]ncm (AT) somewhere (DOT) com[/email]> wrote: Folks, A rhetorical question, but all other things being constant, do aerodynamic qualities of an aircraft change by geographic location? Reason why I ask it is because of the different methods taught of stall recovery of the same a/c type in different countries/schools. e.g. PA28-161 - stall clean: In Aus - Throttle off, release back pressure, flying speed (60KIAS?), apply throttle and climb out.. UK: full throttle, release back pressure but maintain height - when enough a/s, fly away... (at least 2 organisation taught it this way). I know which one I generally prefer, but why the difference for the same a/c type? NCM not enough data points for a valid sample. I think your australian example is an anomalous one. the uk procedure is the correct one for recovery from an incipient stall with zero or minimal loss of height. I use it in the tailwind as well. (only exception would be an aircraft such as a P51 with enormous amounts of torque, then you'd bleed in the power gradually.) P51's and lightly loaded C208B's When I did my endorsement on the Grand Caravan we did some incipient stalls just to see what happens etc. The problem with the Caravan is lack of aileron authority leading up to the stall - you're dancing on the rudder pedals for the last couple of kias! Anyway, the stall warning goes off, VSI goes south. So you grab the power lever and push it smartly to about 3/4 position (still dancing on the rudder pedals), the PT6 spools up (surges a little if you've been rough) then holey snapping duck crap(!) the torque kicks in and you get the wing drop from hell. Boot full of top rudder (pushed to the firewall) and the wing doesn't drop any further but you're in stall recovery with about 30-45 degrees of bank! Good fun really :) James -- Fortune cookies says: BOFH excuse #186: permission denied Back to top Peter Creswick Guest Posted: Sun Apr 04, 2004 3:40 pm    Post subject: Re: Aerodynamic qualities by geographic location Stealth, try use of power to recover from a stall, or incipient stall, in a glider. OK, back to square one. Aerodynamic stalls have to be aerodynamically unstalled, no other means will do. Teaching use of power, specifically increasing power, and even worse, teaching holding, or attempting to hold height, apparently by minimal release of back pressure, as a part of the procedure, is a recipe for disaster, and may indeed be the root cause of most lightie low altitude, low speed, and final turn stall-spin-crunch accidents. People are being trained WRONG thinking. For my money, you want to get the wing unstalled, which means change the angle of attack of the relative airflow downwards, ie, less angle / alpha, which means pitch down, which means stick forward, all with a reasonable degree of smoothness and deliberate but modest haste. Failing to do so only allows the stall or incipient stall to develop further. Playing the power game, especially with big power beasts like P-51's, with heaps of torque, would definitely complicate the issue, facilitating torque induced rotation, which only further worsens the situation, sending everything deep south in a bloody big hurry. Centurion's example is also interesting. The beginning of loss of aileron authority also directly leads you into secondary effects land and the rapid increase in the possibility of an aerodynamic auto rotation, not just "a wing drop", the two are different beasts remember, let alone the torque effects. Dancing on the pedals during this time of the last few knots is also fun as Centurion points out. I had a lot of fun with a Blanik in this regard. I was minimum weight (150 lbs) for the front seat solo with no ballast, so I was able to fly the blanik at lowest AUW and on the aft CG limit. One day, I decided to see what the absolute minimum speed was before it all went south. With full flap, and bringing the speed back ever so slowly, and knowing the ailerons gave some secondary effects at about 38 kias, I held stick centre, and "walked the rudder" into a mushing stall, all the way down to 32 kias, before going south, which was a straight pitch nose down 2 out of 3 times. Once, it went into a full blooded auto rotate and spin, requiring standard recovery (heave the pink handle fully forward as soon as it started to roll) but I think it was caused by a bit of a gust, ie, it was not something a blanik would do by itself, ie, normally you had to force her to auto rotate by a deliberate slight nose high stall complete with out stick and a nudge or more of in rudder to get her to go over, and when it did, it really did ! Back to top Ted Harrison Guest Posted: Sun Apr 04, 2004 9:18 pm    Post subject: Re: Aerodynamic qualities by geographic location "Non Compis Mentis" <ncm (AT) somewhere (DOT) com> wrote Quote: Folks, A rhetorical question, but all other things being constant, do aerodynamic qualities of an aircraft change by geographic location? Not for the purpose of your example. Quote: Reason why I ask it is because of the different methods taught of stall recovery of the same a/c type in different countries/schools. e.g. PA28-161 - stall clean: In Aus - Throttle off, release back pressure, flying speed (60KIAS?), apply throttle and climb out.. This is not an "Australian" thing. It's an individual school or instructor fad. What was the explanation given for failing to use power (slipstream) to help unstall the inboard (earlier stalling) sections of the wings? Quote: UK: full throttle, release back pressure but maintain height - when enough a/s, fly away... (at least 2 organisation taught it this way). I know which one I generally prefer but why the difference for the same a/c type? Somebody mixed stall recovery up with spin recovery? Back to top Martin Taylor Guest Posted: Tue Apr 06, 2004 7:57 am    Post subject: Re: Aerodynamic qualities by geographic location Non said.... Quote: A rhetorical question, but all other things being constant, do aerodynamic qualities of an aircraft change by geographic location? If you're asking a rhetorical question, should you be expecting an answer? Back to top RT Guest Posted: Tue Apr 06, 2004 9:30 am    Post subject: Re: Aerodynamic qualities by geographic location Martin Taylor wrote in message <40726819.38cc1697.bm001 (AT) yahoo (DOT) com.au>... Quote: If you're asking a rhetorical question, should you be expecting an answer? Er...... is that a rhetorical question? :-) Back to top Non Compis Mentis Guest Posted: Tue Apr 06, 2004 12:23 pm    Post subject: Re: Aerodynamic qualities by geographic location Martin Taylor wrote: Quote: Non said.... A rhetorical question, but all other things being constant, do aerodynamic qualities of an aircraft change by geographic location? If you're asking a rhetorical question, should you be expecting an answer? Not to that particular question, but to the ones following.. Back to top Non Compis Mentis Guest Posted: Tue Apr 06, 2004 12:27 pm    Post subject: Re: Aerodynamic qualities by geographic location Non Compis Mentis wrote: Quote: Folks, A rhetorical question, but all other things being constant, do aerodynamic qualities of an aircraft change by geographic location? Reason why I ask it is because of the different methods taught of stall recovery of the same a/c type in different countries/schools. e.g. PA28-161 - stall clean: In Aus - Throttle off, release back pressure, flying speed (60KIAS?), apply throttle and climb out.. UK: full throttle, release back pressure but maintain height - when enough a/s, fly away... (at least 2 organisation taught it this way). I know which one I generally prefer, but why the difference for the same a/c type? NCM Thanks for your replies, NCM Back to top Stealth Pilot Guest Posted: Tue Apr 06, 2004 2:57 pm    Post subject: Re: Aerodynamic qualities by geographic location On Mon, 05 Apr 2004 01:40:57 +1000, Peter Creswick <ventus45 (AT) ihug (DOT) SOMEBODY.com.au> wrote: Quote: Stealth, try use of power to recover from a stall, or incipient stall, in a glider. who flies gliders? btw it equates to getting rid of the drag brakes. Quote: OK, back to square one. Aerodynamic stalls have to be aerodynamically unstalled, no other means will do. Teaching use of power, specifically increasing power, and even worse, teaching holding, or attempting to hold height, apparently by minimal release of back pressure, as a part of the procedure, is a recipe for disaster, and may indeed be the root cause of most lightie low altitude, low speed, and final turn stall-spin-crunch accidents. People are being trained WRONG thinking. For my money, you want to get the wing unstalled, which means change the angle of attack of the relative airflow downwards, ie, less angle / alpha, which means regarding powered aircraft I dont think you are right. the need is to be able to recover from a stall with no loss of altitude, otherwise if you make the mistake of entering a stall on late finals or during a go around you are dead. in a powered aircraft you can be within a gnats whisker of the stall and still be flying, increase the thrust on all the lighties I've flown and you immediately fly out of the stall. if you wait until after you get the nose drop of course then it is too late. in real life you never stall the aircraft unless you are doing it deliberately. so the fly out of an impending stall technique is really intended for the situations when you are flying slow and a loss of situational awareness can occur. for all intending purposes you are only slow during approach or go around and they are manouvers in close proximity to the planetary surface, hence the zero height loss requirement. in the area of stalls the availability of power creates different operational techniques between gliders and powered aircraft. ymmv Stealth Pilot Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AirTalk.org Forum Index -> Planes, gliders and flying in Australia All times are GMT Page 1 of 1   Jump to: Select a forum Aviation----------------alt.aviationAviation safety EnhancementPlanes, gliders and flying in AustraliaAviation et pilotage (Français)rec.aviationAviation (Aerobatics)Hot air, gas balloons and airshipsHang-gliding, paragliding, foot-launched flightAircraft Design & BuildingInstrument Flight RulesAviation (Classifieds)Military AircraftNaval AviationAviation (Miscellaneous Topics)Owning AirplanesAviators (General Discussions)Aviation related productsAircraft RestorationHelicopters and rotary wing aircraftsFlight SimulationSailplanesAviation (Students)Light aircraftFlying related activities in the UK Airports----------------alt.airportsEdinburgh Airport Glasgow Airport Humberside Airport Luton Airport Aberdeen Airport Glasgow Prestwick Airport  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.