X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 09 Dec 2008 08:43:26 -0500 Message-ID: X-Original-Return-Path: Received: from imo-m24.mx.aol.com ([64.12.137.5] verified) by logan.com (CommuniGate Pro SMTP 5.2.10) with ESMTP id 3343042 for lml@lancaironline.net; Mon, 08 Dec 2008 21:47:56 -0500 Received: from Sky2high@aol.com by imo-m24.mx.aol.com (mail_out_v39.1.) id q.bd1.45a038ab (39953) for ; Mon, 8 Dec 2008 21:47:50 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Mon, 8 Dec 2008 21:47:49 EST Subject: Re: [LML] Re: outback gear doors-vibration is back X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1228790869" X-Mailer: AOL 9.1 sub 5000 X-Spam-Flag:NO -------------------------------1228790869 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en "Sucked out" is a weird concept on the bottom of the wing where one would =20 expect hi pressure. Perhaps airflow over a surface produces a local low=20 pressure even though the pressure on the bottom is greater than that on the= top? =20 However, if any air enters at the door leading edge, it is far easier to=20 understand since the door is curved and could act like an inverted wing. T= hen,=20 when the rear is in the slip stream, the forward edge is forced closed and=20= the=20 "wing" stops flying, returning to the start state where air once again ente= rs=20 at the leading edge. Thus, the buzz. =20 Is the wheel well sealed to the cockpit, thus the door does not benefit fro= m=20 the low pressure in the cockpit trying to suck the door in. =20 =20 Interrrrrresting......... =20 Grayhawk =20 =20 In a message dated 12/8/2008 12:55:59 P.M. Central Standard Time, =20 harryleague@comcast.net writes: =20 Just a thought: would a couple of air vents in the doors solve the problem= ?=20 Start small and move larger until the noise stops or the doors stay shut= .=20 =20 Regards,=20 Harry League=20 =20 =20 ____________________________________ =20 From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of=20 marv@lancair.net Sent: Saturday, December 06, 2008 21:46 PM To: lml@lancaironline.net Subject: [LML] Re: outback gear doors-vibration is back =20 Posted for mquinns@aol.com: Dom, AC-DC is not to my taste but listening to them would be far more musical=20 and pleasant than gear door rumblings. Attached is a close up picture of a=20 musical nocturne. Mark -----Original Message----- From: Dominic V. Crain To: lml@lancaironline.net Sent: Fri, 5 Dec 2008 12:06 pm Subject: [LML] Re: outback gear doors-vibration is back I would think that the gear doors rumbling would be far more musical than =20 listening to AC-DC. Cheers Dom VH-CZJ From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of =20 mquinns@aol.com Sent: Friday, 5 December 2008 3:25 PM To: lml@lancaironline.net Subject: [LML] Re: outback gear doors-vibration is back Gerard, I had the same problem. Whenever the airspeed started moving past 210 =20 knots a buzz would start and then turn into a rumble as the plane went =20 faster.=20 If the aircraft was decelerated......to a speed around 205 knots, the=20 rumbling=20 and buzzing would disappear but would reappear if the aircraft accelerated=20 back above 210 knots. I was certain it was the nose gear door (made from=20 fiberglass) so I took the advice in archive and fabricated a much stiffer=20 aluminum door. To my surprise the buzzing and rumbling problem was still=20 there=20 over certain speeds.!!!!???!!!! Fortunately for me, I live at at a place=20 where=20 we formation fly to breakfast every Saturday and I usually fly with the=20 SX-300=20 guys. One of these friends volunteered to go up with me and formate under m= e=20 to =20 see if the problem could be observed. Apparently, the main gear doors=20 trailing edges are being sucked out into the slipstream at certain =20 airspeeds.=20 We repeated the speed runs (accelerate/decelerate) and proble! m was clear. My plane does have a difference with yours which is, even though I have=20 the outback gear, I decided to use the original cutout doors thinking they=20 would create less drag. Don't know whether they do or not but have been=20 unable=20 after many different attempts to keep the doors closed at high speed. In=20 January I will be racing and afterwards plan on doing a major condition=20 inspection (demating wings, removing all control surfaces, etc) and at that= =20 time will fit the original outback gear doors from the option kit. They do=20 appear to be stiffer (I hope they don't generate more drag). I hope that=20 this=20 cures my problem. Some of the Reno racers have recommended stiffening gear=20= =20 doors because this is a common problem for them while racing. If you find a= =20 magic bullet to correct the problem, please post it.=20 Mark Quinn Lancair 360 Spruce Creek Fly-in, Florida -----Original Message----- From: gerardoconnell@optusnet.com.au To: lml@lancaironline.net Sent: Wed, 3 Dec 2008 9:15 pm Subject: [LML] outback gear doors-vibration is back Hi Ian and those whom have had gear door problems -Gerard from Down Under/Up Over has gremlins again Hope you're going well and enjoying you're flying. I'm just writing a quick= =20 note=20 both on and off list as we've been over this ground before.=20 Do you recall discussing the buzzing noise I had some time back which I=20 resolved =20 both by removing the nose gear door and overlapping the main and inboard=20 gear=20 doors to get better "purchase" and stop vibration. Well guess what? Thhe noise is now starting to return-I initially thought= =20 I =20 had the bass turned up too much whilst listening to AC -DC but even with th= e=20 radio off I can appreciate the buzz from outside the aircraft.=20 Perhaps I need to listen to Robbie Williams instead? I originally spent thousands of $ trying various solutions to this problem=20 and =20 the final fix has worked for about 200 hours. I understand that some have=20 also=20 extended the door hinge/bracket to address this problem. In short, my question is this-did you have this buzzing/vibration problem=20 and =20 what methods did you employ before removing the inner gear doors altogether= ?=20 Is=20 this my best short cut to making the problem go away once and for all? Your thoughts would be appreciated including and issues you mar or may nopt= =20 have =20 experienced after removing the inner doors. Cheers, Gerard -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.htm= l Listen to 350+ music, sports, & news radio stations =E2=80=93 including son= gs for=20 the =20 holidays =E2=80=93 FREE while you browse. Start Listening Now! =20 **************Make your life easier with all your friends, email, and=20 favorite sites in one place. Try it now.=20 (http://www.aol.com/?optin=3Dnew-dp&icid=3Daolcom40vanity&ncid=3Demlcntaolco= m00000010) -------------------------------1228790869 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en
"Sucked out" is a weird concept on the bottom of the wing where one wou= ld=20 expect hi pressure.  Perhaps airflow over a surface produces a=20 local low pressure even though the pressure on the bottom is greater th= an=20 that on the top?  However, if any air enters at the door leading edge,=20= it=20 is far easier to understand since the door is curved and could act like an=20 inverted wing.  Then, when the rear is in the slip stream, the forward=20= edge=20 is forced closed and the "wing" stops flying, returning to the start state w= here=20 air once again enters at the leading edge. Thus, the buzz.
 
Is the wheel well sealed to the cockpit, thus the door does not benefit= =20 from the low pressure in the cockpit trying to suck the door in. 
 
Interrrrrresting.........
 
Grayhawk
 
In a message dated 12/8/2008 12:55:59 P.M. Central Standard Time,=20 harryleague@comcast.net writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>

Just a thought:=  =20 would a couple of air vents in the doors solve the problem?   St= art=20 small and move larger until the noise stops or the doors stay=20 shut.

 

Regards,=

Harry=20 League

=  

=  

=

From:On Behalf Of marv@lancair.net
Sent: Saturday, December 06, 2008 2= 1:46=20 PM
To:=20 lml@lancaironline.net
Subject: [LML] Re: outback gear=20 doors-vibration is back

 


Posted for=20 mquinns@aol.com:

 Dom,
     AC-DC is no= t to=20 my taste but listening to them would be far more musical
and pleasant=20= than=20 gear door rumblings. Attached is a close up picture of a
musical=20 nocturne.
 
 Mark
 
 
 -----Origin= al=20 Message-----
From: Dominic V. Crain=20 <domcrain@tpg.com.au>
 To: lml@lancaironline.net
 Se= nt:=20 Fri, 5 Dec 2008 12:06 pm
 Subject: [LML] Re: outback gear=20 doors-vibration is back
 
 
 
 
 I= =20 would think that the gear doors rumbling would be far more musical than=20
listening to=20 AC-DC.
 
  
 
 Cheers
 
&n= bsp;Dom
 
 VH-CZJ
 
  
 
&nb= sp;
From:=20 Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of=20
mquinns@aol.com
 Sent: Friday, 5 December 2008 3:25=20 PM
 To: lml@lancaironline.net
 Subject: [LML] Re: outback=20= gear=20 doors-vibration is=20 back
 
 
  
 
 Gerard,
&nb= sp;  =20 I had the same problem. Whenever the airspeed started moving past 210=20
knots a buzz would start and then turn into a rumble as the plane went= =20 faster.
If the aircraft was decelerated......to a speed around 205 kno= ts,=20 the rumbling
and buzzing would disappear but would reappear if the=20 aircraft accelerated
back above 210 knots. I was certain it was the no= se=20 gear door (made from
fiberglass) so I took the advice in archive and=20 fabricated a much stiffer
aluminum door. To my surprise the buzzing an= d=20 rumbling problem was still there
over certain speeds.!!!!???!!!!=20 Fortunately for me, I live at at a place where
we formation fly to=20 breakfast every Saturday and I usually fly with the SX-300
guys. One o= f=20 these friends volunteered to go up with me and formate under me
to=20
 see if the problem could be observed. Apparently, the main gear=20 doors
trailing edges are being sucked out into the slipstream at certa= in=20 airspeeds.
We repeated the speed runs (accelerate/decelerate) and prob= le!=20 m was clear.
    My plane does have a difference with yo= urs=20 which is, even though I have
the outback gear, I decided to use t= he=20 original cutout doors thinking they
would create less drag. Don't know= =20 whether they do or not but have been unable
after many different attem= pts=20 to keep the doors closed at high speed. In
January I will be racing an= d=20 afterwards plan on doing a major condition
inspection (demating wings,= =20 removing all control surfaces, etc) and at that
time will fit the orig= inal=20 outback gear doors from the option kit. They do
appear to be stiffer (= I=20 hope they don't generate more drag). I hope that this
cures my problem= .=20 Some of the Reno racers have recommended stiffening= gear=20
doors because this is a common problem for them while racing. If you f= ind=20 a
magic bullet to correct the problem, please=20 post it. 
 
 Mark Quinn
 Lancair=20 360
 Spruce Creek Fly-in, Florida
 
 
 -= ----Original=20 Message-----
From: gerardoconnell@optusnet.com.au
 To:=20 lml@lancaironline.net
 Sent: Wed, 3 Dec 2008 9:15 pm
 Subj= ect:=20 [LML] outback gear doors-vibration is=20 back
 
 
  
 
  
&nbs= p;
 Hi=20 Ian and those whom have had gear door=20 problems
 
  
 
 -Gerard from Down=20 Under/Up Over has gremlins=20 again
 
  
 
  
 
&nb= sp;Hope=20 you're going well and enjoying you're flying. I'm just writing a quick=20
note
 
 both on and off
 list as we've been o= ver=20 this ground before.
 
  
 
 Do you=20 recall discussing the buzzing noise I had some time back which I
resol= ved=20
 
 both by removing the nose gear door and overlapping th= e=20 main and inboard gear
 
 doors to get better "purchase" a= nd=20 stop vibration.
 
  
 
 Well guess=20 what?   Thhe noise is now starting to return-I initially thought= I=20
 
 had the bass turned up too much whilst listening to AC= -DC=20 but even with the
 
 radio off I can appreciate the buzz=20= from=20 outside the aircraft.
 
  
 
 Perhap= s I=20 need to listen to Robbie Williams=20 instead?
 
  
 
 I originally spent=20 thousands of $ trying various solutions to this problem
and=20
 
 the final fix has worked for about 200 hours. I unders= tand=20 that some have
also
 
 extended the door hinge/bracke= t to=20 address this problem.
 
  
 
 In shor= t,=20 my question is this-did you have this buzzing/vibration problem and=20
 
 what methods did you employ before removing the inner=20= gear=20 doors altogether?
Is
 
 this my best short cut to mak= ing=20 the problem go away once and for=20 all?
 
  
 
 Your thoughts would be=20 appreciated including and issues you mar or may nopt
have=20
 
 experienced after removing the inner=20 doors.
 
  
 
  
 
&n= bsp;Cheers,
 
  
 
 Gerard
   
 
  
 
  
 <= BR>  
 
  
 
 --
 For=20 archives and unsub=20 http://mail.lancaironline.net:81/lists/lml/List.html
 
  
  
 
 
 
 Listen=20 to 350+ music, sports, & news radio stations =E2=80=93 including songs= for the=20
holidays =E2=80=93 FREE while you browse.
 Start Listening Now= !=20
 
 
 




Make your life easier with all=20= your friends, email, and favorite sites in one place. = Try it now.
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