ron@brl-sem.ARPA (Ron Natalie <ron>) (01/01/70)
> > In article <121@pecnos.UUCP> don@pecnos.UUCP (Don Hopkins) writes: > > >In a high speed dive if the pull-up is too abrupt it is certainly > > >possible to stall the aircraft... > > Until recently I was flying a 152 Aerobat. (The FBO sold it.) Over the > last few years I did inumerable loops. Once I pulled 4 1/4 G's during > the pull-out. I would call this farily abrupt. I have never noticed > any behavior that I would attribute to a stall. > Actually, I never did acrobatics in a 152, but there is a very important secondary stall situation which every good flight instructor will warn you about. When recovering from the typical 152 stall you're still nose down and picking up speed. Now, since you've been told that you should recover in X feet and since you now have plenty of airspeed you horse that puppy back up to straight and level again ***HONK*** stall in a nice straight and level configuration that doesn't automatically fall forward like the typical gentle 152 nose up stalls. -Ron
doug@terak.UUCP (Doug Pardee) (09/27/85)
> > When you take your written test, one of the questions the FAA seems to always > > ask is under what conditions an airplane can stall. The correct answer is at > > any attitude and any airspeed, and they mean it. > > This answer may be correct, but is pretty nebulous. Isn't it better > to say "when the angle of attack is too great"? Even this strikes me as useless, unless you have an AOA indicator (the best of all possible worlds). I find it more practical to consider the stalling condition to be a combination of three somewhat determinable factors: a) airspeed b) gross weight c) G-force At "Max Gross" and 1.0G, the stall speed is (it says here) as specified in the Flight Manual. Well, 'twould be in your best interest to determine empirically what the airspeed indicator reads at stall in the specific plane in question. Stall speed is proportional to the square root of the gross weight. If the plane is currently at 90% of max gross (allowing for fuel burned, etc.) the stall speed will be 5% lower than at max gross. Stall speed is proportional to the square root of the G force. If the plane is held at 2G in a steep bank, the stall speed will be 41% higher than at 1G. So: making steep turns at low airspeed will not induce a stall provided that you allow the nose to drop sufficiently that you stay at 1G. This will, of course, cause you to lose altitude. If the altitude loss becomes intolerable, the "way out" is to roll out of the turn, *not* to pull back on the wheel/stick. Caveat: If the ball is out of center, nobody knows what the stall speed is (nor what the Angle of Attack is). The airflow to the wings is not consistent across the entire wingspan. Another Caveat: Knowing that your stall speed under current weight and G-loads is X knots is only somewhat useful, since you don't know for sure what the airspeed indicator will read when you get to X knots. ... What is this nonsense the FAA (and others) say about being able to stall a plane in any attitude at any airspeed? Try to stall a plane at Vne. It won't stall. (You'd have to pull maybe 15 G's, and the plane will come apart instead :-) -- Doug Pardee -- CalComp -- {calcom1,savax,seismo,decvax,ihnp4}!terak!doug
don@pecnos.UUCP (Don Hopkins) (10/02/85)
> ... What is this nonsense the FAA (and others) say about being able to > stall a plane in any attitude at any airspeed? Try to stall a plane > at Vne. It won't stall. (You'd have to pull maybe 15 G's, and the > plane will come apart instead :-) > -- > Doug Pardee -- CalComp -- {calcom1,savax,seismo,decvax,ihnp4}!terak!doug This may be true for the type of airplane you fly, but consider the modern jet fighter that is capable of withstanding high-G forces without coming apart. In a high speed dive if the pull-up is too abrupt it is certainly possible to stall the aircraft despite the fact you may be doing mach 1 or greater. Name........: Donald F. Hopkins Company.....: Perkin-Elmer Data Systems Group US Mail.....: 106 Apple St., Tinton Falls, N.J. 07724 Phone.......: 201-758-7268 UUCP..(work): ...!{decvax,ucbvax,ihnp4}!vax135!petsd!pecnos!don (home): ...!{decvax,ucbvax,ihnp4}!vax135!petsd!pecnos!buslog!dfh
brad@gcc-bill.ARPA (Brad Parker) (10/11/85)
In article <121@pecnos.UUCP> don@pecnos.UUCP (Don Hopkins) writes: >In a high speed dive if the pull-up is too abrupt it is certainly >possible to stall the aircraft... Could someone who has done this pulling out of a loop describe the sensation? I'd like some accurate words (realizing that is it dependant on the aircraft and configuration). I seem to remember someone here saying that they'd done it on accident (flying an aerobat C-150 after a Citabria? Pulling out too hard/soon?) For some strange reason I have the desire to experience this... (But then, I get a real kick out of spins...) -- J Bradford Parker uucp: seismo!harvard!gcc-bill!brad "She said you know how to spell AUDACIOUSLY? I could tell I was in love... You want to go to heaven? or would you rather not be saved?" - Lloyd Coal
steves@tektools.UUCP (steve shellans) (10/17/85)
> In article <121@pecnos.UUCP> don@pecnos.UUCP (Don Hopkins) writes: > >In a high speed dive if the pull-up is too abrupt it is certainly > >possible to stall the aircraft... > > Could someone who has done this pulling out of a loop describe the > sensation? I'd like some accurate words (realizing that is it dependant > on the aircraft and configuration). I seem to remember someone here > saying that they'd done it on accident (flying an aerobat C-150 after > a Citabria? Pulling out too hard/soon?) Until recently I was flying a 152 Aerobat. (The FBO sold it.) Over the last few years I did inumerable loops. Once I pulled 4 1/4 G's during the pull-out. I would call this farily abrupt. I have never noticed any behavior that I would attribute to a stall. However, I should also add that I do not do 'textbook' loops. They are elongated on the back side, so that the plane has considerably more speed when pullup is initiated. This may explain the absence of stall at 4 1/4 G's. If I still had access to the Aerobat, I'd try it for ou at slower speeds. Steve Shellans decvax!tektronix!tektools!steves
daver@hp-pcd.UUCP (daver) (10/19/85)
I am the person who reported stalling an aerobat while pulling up in a loop. The aircraft was near gross for acro, with myself, an instructor and almost 1/2 fuel, which may have been necessary for the stall to occur. What it felt like was the plane stopped flying as it had been and broke down and to the left as a 150 normally does in an accelerated stall. Recovery was very easy, given the speed of the aircraft - I just released the back pressure slightly and the plane started flying again. One of the nice things about acro training is that you learn to recover from truly unusual attitudes (one of my instructors had me recover from acro attitudes under the hood - very interesting). Dave Rabinowitz hplabs!hp-pcd!daver
john@gcc-milo.ARPA (John Allred) (10/22/85)
In article <2900006@hpcvrd.UUCP> daver@hp-pcd.UUCP (daver) writes: >I am the person who reported stalling an aerobat while pulling up in a loop. >The aircraft was near gross for acro, with myself, an instructor and almost >1/2 fuel, which may have been necessary for the stall to occur. What it felt >like was the plane stopped flying as it had been and broke down and to the left >as a 150 normally does in an accelerated stall. Recovery was very easy, given >the speed of the aircraft - I just released the back pressure slightly and the >plane started flying again. One of the nice things about acro training is that >you learn to recover from truly unusual attitudes (one of my instructors had me >recover from acro attitudes under the hood - very interesting). > >Dave Rabinowitz >hplabs!hp-pcd!daver GOOD DEAL!! Unfortunately, acro training is not required for all private pilots. If it were, there might be a lot fewer dead pilots around. -- John Allred General Computer Company uucp: seismo!harvard!gcc-milo!john ^^^^ note new path-------------||
rjn@hpfcla.UUCP (10/22/85)
re: stalling the C150 at any attitude... The 150s I flew (we're probably talking '63 to '67 models here) had a "deep stall" mode. I could get it to sink at 1000 fpm or more in a level attitude with power off. Note - if you use this configuration on final approach, it will be. Regards, Hewlett-Packard Bob Niland 3404 East Harmony Road hplabs!hpfcla!rjn Fort Collins CO 80525
paul@ubvax.UUCP (Paul Fries) (10/23/85)
In article <437@brl-sem.ARPA> ron@brl-sem.ARPA (Ron Natalie <ron>) writes: > When recovering from the typical 152 stall you're still nose down and > picking up speed. Now, since you've been told that you should recover > in X feet and since you now have plenty of airspeed you horse that puppy > back up to straight and level again ***HONK*** stall in a nice straight > and level configuration that doesn't automatically fall forward like the > typical gentle 152 nose up stalls. > > -Ron I am a STUDENT PILOT, so please, flame me not if this is incorrect. I had the same problem for a while, i.e. in attempting to minimize altitude loss in a stall, I would get the stall horn after apparently having recovered. My instructor corrected my procedure with good results. My problem was that I was pushing the nose down TOO FAR in an effort to break the stall. His correction was to "RELEASE BACK PRESSURE" on the elevator to bring the nose back to the horizon, instead of pushing the nose down (below the horizon). Pushing the nose down will certainly get your airspeed up, but you will be losing more altitude than you want. The aircraft is diving instead of just recovering from the stall. When you abruptly pull the nose back up to minimize the altitude loss, the relative wind is momentarily coming from somewhere below the nose of the aircraft, and you have increased the angle of attack (i.e. the angle between the relative wind and the chord of the wing) past the critical angle. Thus, the wing stalls again. Of course, this stall seems to "evaporate" as the direction of flight becomes more level, since you have plenty of airspeed once the angle of attack is reduced. If you only "RELEASE BACK PRESSURE", it will take a little longer to get the airspeed, but the aircraft will be in the correct attitude once you get it. You will not need to "horse that puppy back up to straight and level", and you will not have lost more than the 50-100 feet that was the goal. My instructor points out that this is an example of the rule, "an aircraft can be stalled in ANY attitude at ANY airspeed. All that is required is to increase the angle of attack beyond the critical angle". As previously stated, I am a STUDENT. Constructive criticism is welcome.