X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml Date: Thu, 16 Nov 2006 13:55:13 -0500 Message-ID: X-Original-Return-Path: Received: from mtai03.charter.net ([209.225.8.183] verified) by logan.com (CommuniGate Pro SMTP 5.1.2) with ESMTP id 1573240 for lml@lancaironline.net; Thu, 16 Nov 2006 13:46:17 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.225.8.183; envelope-from=troneill@charter.net Received: from aa02.charter.net ([10.20.200.154]) by mtai03.charter.net (InterMail vM.6.01.06.01 201-2131-130-101-20060113) with ESMTP id <20061116184540.VBDP1482.mtai03.charter.net@aa02.charter.net> for ; Thu, 16 Nov 2006 13:45:40 -0500 Received: from axs ([75.132.198.100]) by aa02.charter.net with SMTP id <20061116184540.PJET19063.aa02.charter.net@axs> for ; Thu, 16 Nov 2006 13:45:40 -0500 X-Original-Message-ID: <005701c709af$6a253aa0$6501a8c0@axs> From: "terrence o'neill" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: Down anywhere !! spinning X-Original-Date: Thu, 16 Nov 2006 12:45:40 -0600 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0054_01C7097D.1F45F970" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2905 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 X-Chzlrs: 0 This is a multi-part message in MIME format. ------=_NextPart_000_0054_01C7097D.1F45F970 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable > Not in an actual spin, where one wing is stalled, no. If the = instrument is=20 > on the left side of the panel the ball will deflect to the left in a = spin,=20 > no matter which direction you are spinning. If the instrument is on = the=20 > right the ball will always deflect to the right. >=20 > Tom Gourley Hmmm... Tom, what airplanes are we talking about? C152s? If it had two = needle-ball isntruments, one on the left and one of the rightpanel, = would they show the plane was yawing both ways at once?. This is = strange. I was recalling experience from unusual attitude recovery training in = SNJs 50 years ago... the needle and ball was in the middle of the panel. Step on the ball -- was the procedure to recover from any unusual = attitude ... the instructor had you under the 'bag' so you couldn't see = outside, and then put the plane through some crazy gyrations, and = finally said 'You've got it." You might be upside down, or going = straight up, or whatever. A little game for fun. Anyway, you had to = recover. Then I'd just do the procedure, and it worked quickly, every = time. Step on the ball to stop the yaw and the turn, then apply or = reduce power depending on if the altimeter was going up or down, while = applying elevator , up or down, to stop altitude changing up or down. But I don't know it any one of those unusual attitudes was a spin. So = my suggestion to 'step on the ball' for spin recovery might be wrong. = Sorry about that.=20 But your info that the ball is useless or ambiguous for seeing yaw in a = spin is puzzing. So I did some refresher reading about spins. Back when I was designing experimentals i did a lot of reading about = spins and characteristics of planes that are good or bad for recovery. = In 1960 NASA did TR R-57 "Status of Spin Research"; and in 1977 NASA = Tech Paper 1009 "Spin Tnnel Investigation of Spinning Characteristics of = Typical Single-Engine GenAv Airplane Designs -- I - Low Wing Model A: = Effect of Tail Configurations." Langley's been spin-tunnel testing since about 1940, and by now have = certainly tested about 1000 dirrerent configurations with good = correlation between the mdels and the airpalnes. An interesting addition to NASA spin info I found was NASA TT GF-442, = which is "Flight Testing of Aircraft" by M.G. Kotik et al, USSR = aeronautical engineers prepared for students at their aviation colleges, = a translation with ten pages of descriptions of both normal and inverted = spins, and of each of those, stable or unstable, and of the three types = of stable, and three types of unstable. Also given are the four types = of recovery. All four could be used for normal spins, and three for = inverted spins, and it noted which is appropriate for which type of = spin. The types were 1. Rudder, elevator and ailerons neutral; 2. = Rudder agaisnt, elev neutral after 2-4 seconds, and ail neutral. 3. Rud = against, and after 3-6 sec., elev against full down, ail neutral; 4. = Same as 3., but simulatneously with rudder, the ailerons are deflected = with the spin. ... pretty much what we do. The report describes the normal spin as occuring at "medium to low = altitudes, with extended duration, at high angles of attack, at very = high rates of magnitude of rate of rotation with very slight = oscillations." It defines (on p. 284) "The spin axis is the axis of the spiral-like = trajectory of motion of the aircraft's center of gravity in the spin, = and the spin radius is the radius of the spiral along which the = aircraft's center of gravity moves in the steady state spin regime." = That is, the aircraft does not spin around it's own CG, but it and its = CG whips around outward on a radius from the spin axis. So there's a = radial accelleration there ... which will move a slip-ball, depending on = how the slip instrument is aligned. The ball has to show an = accelleration ... that's what it does. I don't see how it could show = opposite accellerations depending on which side of the panel it's on, U = NLESS the spin axis of the plane you're describing is right through the = middle of the plane... but then how could the plane spin?... with one = wing going backwards? Then the ball wouldn't deflect at all if it was in the middle of the = panel, or would show accelleration left or right if you moved the ball = to the left or right of the axis. But how can any plane spin about it's = own CG? Is one of your wings going backward? One wing has to be stalled, and the other unstalled to provide energy = for autorotation. =20 I guess what's really important for spin recovery IFC is seeing the = direction of rotation ... and that should be the DG's needle. Would that be right? If you're turning right, then step on the opposite = rudder? Maybe this rumination will help us understand what's going on. Terrence O'Neill ------=_NextPart_000_0054_01C7097D.1F45F970 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
> Not in an = actual spin,=20 where one wing is stalled, no.  If the instrument is
> on = the left=20 side of the panel the ball will deflect to the left in a spin,
> = no=20 matter which direction you are spinning.  If the instrument is on = the=20
> right the ball will always deflect to the right.
> =
> Tom=20 Gourley
 
Hmmm... Tom, what = airplanes are=20 we talking about? C152s?  If it had two needle-ball isntruments, = one on the=20 left and one of the rightpanel, would they show the plane was yawing = both ways=20 at once?. This is strange.
 
I was recalling = experience from=20 unusual attitude recovery training in SNJs 50 years ago... the needle = and ball=20 was in the middle of the panel.
Step on the ball = -- was=20 the procedure to recover from any unusual attitude ... the instructor = had you=20 under the 'bag' so you couldn't see outside, and then put the plane = through some=20 crazy gyrations, and finally said 'You've got it." You might be upside = down, or=20 going straight up, or whatever.  A little game for fun. = Anyway, you had to = recover. =20 Then I'd just do the procedure, and it worked quickly, every time. Step = on the=20 ball to stop the yaw and the turn, then apply or reduce power depending = on if=20 the altimeter was going up or down, while applying elevator , up or = down, to=20 stop altitude changing up or down.
 
But I don't know it = any one of=20 those unusual attitudes was a spin.  So my suggestion to 'step = on the=20 ball' for spin recovery might be wrong.  Sorry about that. =
But your info that = the ball is=20 useless or ambiguous for seeing yaw in a spin is puzzing.  = So I did some refresher = reading about=20 spins.
 
Back when I was = designing=20 experimentals i did a lot of reading about spins and characteristics of = planes=20 that are good or bad for recovery.  In 1960 NASA did TR R-57 = "Status of=20 Spin Research"; and in 1977  NASA Tech Paper 1009 "Spin Tnnel = Investigation=20 of Spinning Characteristics of Typical Single-Engine GenAv Airplane = Designs -- I=20 - Low Wing Model A: Effect of Tail Configurations."
Langley's been = spin-tunnel=20 testing since about 1940, and by now have certainly tested = about 1000 dirrerent = configurations with=20 good correlation between the mdels and the airpalnes.
An interesting = addition to NASA=20 spin info I found was NASA TT GF-442, which is  "Flight = Testing of=20 Aircraft" by M.G. Kotik et al, USSR aeronautical engineers prepared for = students=20 at their aviation colleges, a translation with ten pages of descriptions = of both=20 normal and inverted spins, and of each of those, stable or unstable, and = of the=20 three types of stable, and three types of unstable.  Also given are = the=20 four types of recovery.  All four could be used for normal = spins, and=20 three for inverted spins, and it noted which is appropriate for = which type=20 of spin.  The types were 1. Rudder, elevator and ailerons neutral; = 2.=20 Rudder agaisnt, elev neutral  after 2-4 seconds, and ail = neutral. 3.=20 Rud against, and after 3-6 sec., elev against full down, ail neutral; 4. = Same as=20 3., but simulatneously with rudder, the ailerons are deflected with the=20 spin.  ... pretty much what we do.
  The report = describes the=20 normal spin as occuring at "medium to low altitudes, with extended=20 duration, at high angles of attack, at very high rates of magnitude of = rate of=20 rotation with very slight oscillations."
    = It defines=20 (on p. 284) "The spin axis is the axis of the spiral-like trajectory of = motion=20 of the aircraft's center of gravity in the spin, and the spin radius = is the=20 radius of the spiral along which the aircraft's center of gravity = moves in=20 the steady state spin regime." That is, the aircraft does not spin = around it's=20 own CG, but it and its CG whips around outward on a radius from the = spin=20 axis. So there's a radial accelleration there ... which will move a = slip-ball, depending on how the slip instrument is aligned.  The = ball has=20 to show an accelleration ... that's what it does.  I don't see how = it could=20 show opposite accellerations depending on which side of the panel it's = on, U=20 NLESS the spin axis of the plane you're describing is right through the = middle=20 of the plane... but then how could the plane spin?... with one wing = going=20 backwards?
 Then the ball = wouldn't=20 deflect at all if it was in the middle of the panel, or would show = accelleration=20 left or right if you moved the ball to the left or right of the = axis. =20 But how can any = plane spin=20 about it's own CG?  Is one of your wings going = backward?
One wing has to be = stalled, and=20 the other unstalled to provide energy for autorotation.  =
 
 I guess = what's really=20 important for spin recovery IFC is seeing the direction of rotation = ... and=20 that should be the DG's needle.
Would that be = right?  If=20 you're turning right, then step on the opposite rudder?
 
Maybe = this rumination will=20 help us understand what's going on.
 
Terrence = O'Neill
 
 
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