X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 20 May 2006 17:28:30 -0400 Message-ID: X-Original-Return-Path: Received: from imo-d04.mx.aol.com ([205.188.157.36] verified) by logan.com (CommuniGate Pro SMTP 5.0.9) with ESMTP id 1121089 for lml@lancaironline.net; Sat, 20 May 2006 08:32:31 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.157.36; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-d04.mx.aol.com (mail_out_v38_r7.5.) id q.386.3293d1a (39332) for ; Sat, 20 May 2006 08:31:40 -0400 (EDT) From: Sky2high@aol.com X-Original-Message-ID: <386.3293d1a.31a0662c@aol.com> X-Original-Date: Sat, 20 May 2006 08:31:40 EDT Subject: Re: [LML] Re: IVP Crash, Lancair handling characteristics X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1148128300" X-Mailer: 9.0 Security Edition for Windows sub 5300 X-Spam-Flag: NO -------------------------------1148128300 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en In a message dated 5/20/2006 6:09:37 A.M. Central Standard Time, =20 domcrain@tpg.com.au writes: Hmmm.=20 I think I have a comment worth posting on the tail size.Now, here in OZ I=20 have a =E2=80=9Clarge tail=E2=80=9D 320.=20 Yet, it seems that there were two ways of determining the =E2=80=9Clarge ta= il=E2=80=9D=20 design when the local authority demanded it.One was to create a new 25% lar= ger =20 horizontal stab with the elevator full width, and the elevator horns wrapped= =20 around the ends.The other was to extend the horizontal stab the 25% while=20 retaining the same elevator width. ( Thus, my request to Grayhawk for a mea= sure=20 of the length of his tail =E2=80=93 er, elevator - ahem!) Now, at approach speeds, I find I run out of pitch trim at about the point=20 of stabilized approach with landing flap (30) on final.This means that the=20 there is always an ever so slight tendency for pitch down at that speed.Whi= ch in=20 turn means stability.Now, Airbus, in its wisdom, and for those who have=20 flown or still fly =E2=80=98em know, decided Lancair had a great idea with t= his nose down=20 pitch stability on approach.=E2=80=98Cos at 100=E2=80=99 on final, the elev= ator computer=20 takes a snapshot of the pitch angle, and retains that in memory.Then at 50= =E2=80=99 the=20 elevator computer commences a positive nose down pitch which demands the=20 pilot commences a flare into the landing.Bloody marvelous mates.=20 Also I had the privilege of flying Bill and Sue=E2=80=99s 320 at Fredericks= burg last=20 year, although I suggest Bill would suggest the term, =E2=80=9Cfly=E2=80= =9D, is a gross=20 exaggeration in my case, and confess I couldn=E2=80=99t tell the difference= between my=20 tail and theirs.What I found a mystery was the over-control I exhibited in=20 both pitch and roll axes. Mine is very stable in both areas.=20 Dom, =20 Egads, I forgot to do the measuring of my almost "built as designed" small =20 tail. Nothing was increased in size (except the pilot girth) - not the mot= or=20 (320), the mount or the tail. The "almost" is that the empennage flying=20 surfaces are thinner than most, improperly placing more faith in the molded= skins=20 than the rib plans. Oh, and a shorter bellcrank. =20 Lancair 300 series characteristics - Hmmmm, I am able to trim to almost =20 neutral thru all normal speeds and flap deployments (full 45 degrees). I don= 't =20 like to totally trim out pitch forces on final as I prefer to feel some sma= ll=20 force against my hand (uh, fingers). I have landed with the only fuel bein= g 4=20 gals in the header (forward CG) and have found full elevator authority to d= o=20 so. =20 =20 I do run out of nose down trim at race speeds. However, I will not further= =20 adjust for the more needed nose down trim at race speeds as I prefer to be=20 holding the necessary wee bit of nose down force. Should I start to daydre= am,=20 I will climb rather than descend into the landscape beneath me. =20 BUT, there are different trim mechanisms, each with its own pros and cons: =20 1. I am using the shortened elevator bellcrank (3" instead of 4"), thus =20 shortening the stick throw by 25% and increasing the stick forces in pitch.= I=20 also use the Dick Reichel geared walnut trim wheel (almost matching the tea= k=20 grips) with stiffer than normal springs. The drawback of a spring bias tri= m=20 system is the control surface same direction movement dead band force. Tha= t=20 is, if the springs are holding "up" elevator, it takes little force to star= t to=20 move the elevator further up and more than normal force to move it down=20 against the more compressed positioning spring. =20 2. Trim tabs are frequently used and require little deflection at cruise=20 speed for effectiveness. They sometimes lose effectiveness at slow speeds=20= where=20 the elevator may become sensitive to small forces in any direction. This=20 may be the case that some have indicated where excessive elevator movement=20 (even apparent control reversal) seems necessary and might lead to pilot in= duced=20 oscillations. Some of this problem may lie in the size of the trim tab. =20 Standard certificated airplanes seem to have rather large tabs in proportio= n to=20 the elevator size. =20 =20 Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) Abnegate Exigencies! -------------------------------1148128300 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en
In a message dated 5/20/2006 6:09:37 A.M. Central Standard Time,=20 domcrain@tpg.com.au writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3D"Times New Roman" color=3D#= 0000ff=20 size=3D3>

= Hmmm.

= I think I have a comment worth post= ing on=20 the tail size.Now, here in OZ I ha= ve a=20 =E2=80=9Clarge tail=E2=80=9D 320.

= Yet, it seems that there were two w= ays of=20 determining the =E2=80=9Clarge tail=E2=80=9D design when the local authori= ty demanded=20 it.One was to create a new 25% larger=20 horizontal stab with the elevator full width, and the elevator horns wrapp= ed=20 around the ends.The other was to ext= end the=20 horizontal stab the 25% while retaining the same elevator width. ( Thus, m= y=20 request to Grayhawk for a measure of the length of his tail =E2=80=93 er,=20= elevator -=20 ahem!)

Now, at= approach=20 speeds, I find I run out of pitch trim at about the point of stabilized=20 approach with landing flap (30) on final.This means that the there is always= an=20 ever so slight tendency for pitch down at that speed.Which in turn means=20 stability.Now, Airbus, in its wisdom, and for= those=20 who have flown or still fly =E2=80=98em know, decided Lancair had a great idea with this nose down pitch stab= ility=20 on approach.=E2=80=98Cos at 100=E2=80=99 on final, the elevator computer tak= es a snapshot=20 of the pitch angle, and retains that in memory.Then at 50=E2=80=99 the elevator co= mputer=20 commences a positive nose down pitch which demands the pilot commences a f= lare=20 into the landing.Bloody marvelous=20 mates.

= Also I had the privilege of flying=20= Bill=20 and Sue=E2=80=99s 320 at Fredericksburg last year, although I suggest Bill= would=20 suggest the term, =E2=80=9Cfly=E2=80=9D, is a gross exaggeration in my cas= e, and confess I=20 couldn=E2=80=99t tell the difference between my tail and theirs.What I found a mystery was the=20 over-control I exhibited in both pitch and roll axes. Mine is very stable=20= in=20 both areas.

Dom,
 
Egads, I forgot to do the measuring of my almost "built as designed" sm= all=20 tail.  Nothing was increased in size (except the pilot girth) - not the= =20 motor (320), the mount or the tail.  The "almost" is that the empennage= =20 flying surfaces are thinner than most, improperly placing more faith in the=20 molded skins than the rib plans. Oh, and a shorter bellcrank.
 
Lancair 300 series characteristics - Hmmmm, I am able to trim to almost= =20 neutral thru all normal speeds and flap deployments (full 45 degrees). I don= 't=20 like to totally trim out pitch forces on final as I prefer to feel some=20 small force against my hand (uh, fingers).  I have landed with the= =20 only fuel being 4 gals in the header (forward CG) and have found full elevat= or=20 authority to do so. 
 
I do run out of nose down trim at race speeds.  However, I will no= t=20 further adjust for the more needed nose down trim at race speeds as I=20 prefer to be holding the necessary wee bit of nose down force.  Should=20= I=20 start to daydream, I will climb rather than descend into the landscape benea= th=20 me.
 
BUT, there are different trim mechanisms, each with its own pros and=20 cons:
 
1. I am using the shortened elevator bellcrank (3" instead of 4"), thus= =20 shortening the stick throw by 25% and increasing the stick forces in=20 pitch.  I also use the Dick Reichel geared walnut trim wheel (almo= st=20 matching the teak grips) with stiffer than normal springs.  T= he=20 drawback of a spring bias trim system is the control surface same direc= tion=20 movement dead band force.  That is, if the springs are holdin= g=20 "up" elevator, it takes little force to start to move the elevator furt= her=20 up and more than normal force to move it down against the more compressed=20 positioning spring.
 
2. Trim tabs are frequently used and require little deflection at=20 cruise speed for effectiveness.  They sometimes lose effectiveness at s= low=20 speeds where the elevator may become sensitive to small forces in any=20 direction.  This may be the case that some have indicated where excessi= ve=20 elevator movement (even apparent control reversal) seems necessary= and=20 might lead to pilot induced oscillations.  Some of this problem may lie= in=20 the size of the trim tab.  Standard certificated airplanes seem to have= =20 rather large tabs in proportion to the elevator size.
 
 
Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)

Abnegate Exigencies!
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