X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 06 Oct 2013 19:37:29 -0400 Message-ID: X-Original-Return-Path: Received: from nm32-vm0.bullet.mail.bf1.yahoo.com ([72.30.239.136] verified) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTPS id 6504629 for lml@lancaironline.net; Sun, 06 Oct 2013 18:53:10 -0400 Received-SPF: none receiver=logan.com; client-ip=72.30.239.136; envelope-from=chris_zavatson@yahoo.com Received: from [98.139.214.32] by nm32.bullet.mail.bf1.yahoo.com with NNFMP; 06 Oct 2013 22:52:37 -0000 Received: from [98.139.212.218] by tm15.bullet.mail.bf1.yahoo.com with NNFMP; 06 Oct 2013 22:52:37 -0000 Received: from [127.0.0.1] by omp1027.mail.bf1.yahoo.com with NNFMP; 06 Oct 2013 22:52:37 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 255524.87442.bm@omp1027.mail.bf1.yahoo.com Received: (qmail 33136 invoked by uid 60001); 6 Oct 2013 22:52:36 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Rocket-MIMEInfo:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=iGL7IPmmgM8t0M3Fkk3eqPTOege9Qu61nChzTQ14rNQKRnu4JoJB82rL4PcGC2jU+FLY3iYHTTm9Ey4IR2AUc9+L91Ezjmluvd3EseqWnMcOykGCb4qEU+nt4KrS1kBeXRdDi7gMA2Ql6gGvmd3El0joZuaHuB7rVRE1rilN8J8=; X-YMail-OSG: T1RkViwVM1kPHqHeQ_JLhErcG7nqwp_OIlFxuUGsGGfFmBv jArvvU4EY2cCslYHY6wqrQOnMGyibfOHMyqVFJEiDO_yYXk024vEEwKowdho DY5DPiOjfPhFvHVyTlj4viHK8n8kJvn8QsxqqLmPShd.P2FX_QbSHw8rlLpA EueqStopSuB6hMo.N2OC4ldf2F3STTlrud6BtFEWE4Qn1aGOpNtdFlcYijNe YRnCQCjpQGaJ39l08eezwMwfgaMKg4GCj.EkWbt0RKcwLRnUDwKNfS4wtBTQ pJflxHirVIUC215xEHrSW.fKLqEhxBt1Gy8B1OOTPs6cwWoNdiCiIKwnLQLP 2GeTRy5NtKKm0z4Wu.yl_DARy_LJmH_cl5kZQFerzhFP5ZDH6hJy6EcB5QZs iFRz7yt8HGGE6n4KAfUGvar_5sOTIobXFxoDUvCc4X5_kWMJuPthcEv3ahDW yeRl.HqMs_Jnh73bDK4c8wlbrPI0TAiHLRpARUR2JS3enWVvhFUHMdo70BIj _OO92vg4oeCV9FIjD84DD2ovCHaytidPvi4Pic4MmS7fOqU7zmJAMzyHW.TR KTwJayNRXI9YPaaasrrB76Z9zTi3RJrGSbFUzo4KU5qS3uF3TkL5ZiQBrLWI Zt7pUbdJ07.aLWxUr7FSZnqJnxLhsFINYoKia4S1qD_WOABKFc4kcNEnKnUQ IgjwFX.EBuKFYPTMP16jlyCJQ6qWw_R6hU67ccSV8ES.7mGbS0jTfRJRa_wv nVg-- Received: from [172.14.16.72] by web121601.mail.ne1.yahoo.com via HTTP; Sun, 06 Oct 2013 15:52:36 PDT X-Rocket-MIMEInfo: 002.001,U2NvdHQsCkl0IHNvdW5kcyBsaWtlIHlvdSBhcmUgbWl4aW5nIHRoZSB0ZXJtcyBmb3IgdHVyYnVsZW50IGFuZCBzZXBhcmF0ZWQgZmxvdy7CoCBUaGV5IGFyZSBkZWZpbml0ZWx5wqBub3QgdGhlIHNhbWUuIMKgU2VwYXJhdGVkIGlzIHZlcnkgYmFkIHdoaWxlwqB0dXJidWxlbnQgdXN1YWxseSBqdXN0IGFkZHMgZHJhZy7CoCBUdXJidWxlbnQgZmxvd8KgaXMgY2hhcmFjdGVyaXplZCBiecKgYSBtaXhpbmcgLWFuZCB0cmFuc2ZlciBvZiBlbmVyZ3ktIGJldHdlZW4gdGhlIHN0cmVhbSBsaW5lcy7CoCBZb3VyIHMBMAEBAQE- X-Mailer: YahooMailWebService/0.8.160.587 References: X-Original-Message-ID: <1381099956.26140.YahooMailNeo@web121601.mail.ne1.yahoo.com> X-Original-Date: Sun, 6 Oct 2013 15:52:36 -0700 (PDT) From: Chris Zavatson Reply-To: Chris Zavatson Subject: Re: [LML] Re: 320/360 performance and stability X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-1977980688-632736007-1381099956=:26140" ---1977980688-632736007-1381099956=:26140 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Scott,=0AIt sounds like you are mixing the terms for turbulent and separate= d flow.=A0 They are definitely=A0not the same. =A0Separated is very bad whi= le=A0turbulent usually just adds drag.=A0 Turbulent flow=A0is characterized= by=A0a mixing -and transfer of energy- between the stream lines.=A0 Your s= moke particles would have been quickly diluted in the air farther off the w= ing surface once the flow transitioned to turbulent.=A0 Truly separated flo= w over 40% of the wing would have had you falling from the sky.=0AThere sho= uld be no separation all the way to the trailing edge - the exception being= the short span from wing trailing edge to flap leading edge.=A0 This is wh= y the=A0next surface is sometimes placed just slightly higher than the prec= eding trailing edge and with a rounded leading edge.=A0 It is meant to catc= h and reattach the flow from the preceding surface.=0AYou can see flow sepa= ration on the upper surface of the flap at +10 degrees in TP-1865 once you = hit about 5 degrees AoA.=A0 Pressure recovery stops at that point on the su= rface.=A0 In practice you see this while lowering the flaps in rain.=A0 At = separation, the rain drops turn around and start running forward on the upp= er surface of the flap.=A0=0ATurbulent flow can be coaxed back to laminar i= f there is a strong favorable pressure gradient accelerating the flow.=A0= =A0A bug right on the leading edge is not as bad as one 6 inches back on th= e wing.=A0 =0AIf there is a separation problem, zigzag tape and vortex gene= rators can be used to energize the flow before it separates.=A0 Once it sep= arates, it is generally game over.=A0 There are exceptions, but=A0not direc= tly applicable here.=A0=0A=A0=0AChris Zavatson=0AN91CZ=0A360std=0Ahttp://ww= w.n91cz.net/=0A=A0 =0A=0A________________________________=0A From: "Sky2hig= h@aol.com" =0ATo: lml@lancaironline.net =0ASent: Sunday, = October 6, 2013 7:31 AM=0ASubject: [LML] Re: 320/360 performance and stabil= ity=0A =0A=0A=0ABill, =0A=0AThe intersection on the upper wing is crucial = to the performance of the =0Awing in reflex.=A0 Laminar flow on=A0the prope= rly smooth upper wing =0Asurface is over 60% of the chord.=A0 The reflexed = portion of the flap allows =0Afor re-attachment of the airflow and a reduct= ion in drag.=A0 =0A=0AI have seen=A0results of the laminar flow by flying = through smokey air =0Aover the central states in September (some years ago)= with some bugs on the =0Aleading edge.=A0 A stop in Boze on my way to the = Labor Day factory fly in had =0Ame looking down the wing into the setting s= un whilst I was tying down.=A0 I =0Aobserved smoke particle marked=A0V's em= anating from bugs obtained on takeoff =0Ain Illinois and those V's easily e= xtended back more than 60% of the chord before =0Athere was separation.=A0 = If only I had taken pictures (uh, this was before =0Adigital cameras in eve= ryone's smart-ass phones)=A0 =0A=0ASee the "Aerodynamics for Naval Aviator= s" manual for the consequence of =0Awing dirtying particles being closer to= gether than 1" resulting in loss of =0Alaminar flow. =0A=0AIn another aircr= aft I had=A0obtained a "dog-bone" cross section shaped =0A(along the chord)= wooden prop that was more efficient and quieter than a more =0Anormal airf= oil shaped prop.=A0 Why?=A0 Because the separated air =0Areattached itself = to the rise in the surface somewhat=A0after the mid =0Apoint.=A0=A0 =0A=0AI= believe the reflexed wing accomplishes a similar reattachment on the =0Aup= per surface. =0A=0ASome builders may not treat the lower wing surface with = proper respect in =0Athe area under the main spar where the D-section and t= he bottom skin are =0Ajoined.=A0 It is crucial that this area be smooth (no= waviness) because the =0Aflow attachment=A0remains much=A0further back=A0t= han 60%.=A0 Indeed, =0Athe concave shape of the flap bottom may be importan= t to the performance of the =0Awing when at 0-reflex.=A0 Those of us that w= ere trying to achieve max speed =0Adidn't really care whether the=A0 wing p= erformed efficiently at moderate =0Aspeeds ( I only considered two speeds -= max cruise and approach to =0Alanding).=A0 Remember that one would prefer = that the re-joined air at the TE =0Ameet at the same speed so no additional= =A0TE drag is introduced. =0A=0AThe aileron flat shape and squared off 1/4"= deep TE is similar to those =0Aseen on jets.=A0 I believe this is for incr= eased control surface =0Aeffectiveness regardless of flap position.=A0 (BTW= , I had mine =0Aboth=A0rigged slightly higher than the -7 degrees reflex - = a separate =0Adiscussion).=A0 =0A=0AAnyway, perhaps flattening the bottom o= f the reflexed=A0flap may reduce =0Adrag - it would be interesting to see= =A0comparable before and after =0Adata. =0A=0AIn the early days some people= tried zig-zag tape to try to re-attach air to =0Athe lower wing surface.= =A0 I don't think it was very successful.=A0 Such =0Atape was used by glide= r folk for that purpose, but we are talking about =0Asignificantly differen= t air speeds and probably different thickness boundary =0Alayers. =0A=0AThe= question would be if the drag induced by vortex generators exciting =0Asep= arated air would be less than the reduction in drag created by an such an = =0Aattempt to re-attach the air flow?=A0 This as opposed to the change in t= he =0Aair flow at reflex by flattening the bottom of the flap. =0A=0AHmmmmm= m ............ =0A=0ABack to my rocking chair now ..... =0A=0AGrayhawk =0A= =0AIn a message dated 10/6/2013 7:45:10 A.M. Central Daylight Time, =0Awfha= nnahan@yahoo.com writes: =0A=0A> =0A>=A0 =0A>=0A>=A0Tom, thanks for sharing= your work.=0A>=0A>Just wondering if you, or anyone else, =0A tried vorte= x generators in the concave wing/fuselage intersection behind the =0A spar= . The idea being to reduce drag by maintaining attached airflow in that =0A= region without the big mod.=0A>=0A> =0A>Regards, =0A>Bill Hannahan =0A>= =0A>wfhannahan@yahoo.com =0A>=0A> =0A>=0A>________________________________= =0A> From: "dudewanarace@yahoo.com" =0A>To: lml@lan= caironline.net =0A>Sent: Wednesday, October 2, 2013 5:49 AM=0A>Subject: [L= ML] 320/360 performance and stability=0A> =0A>=0A>=0A>Readers, =0A>I have = been watching this conversation with interest. =A0I have some odd experie= nces with stability in my small tail 360 that was improperly built (not by= me). =A0Geez, that is going to hurt resale.. haha =0A>=0A> =0A>Anyway, I = have been waiting to comment as it will just fog the data that has been pr= esented given my totally odd arrangement and lack of any real data. =A0All= of my 'data' is seat of the pants, thus not worth mentioning. =A0But, fig= ured I could expand on an envelope probably few have visited just for inte= resting reading. =0A>=0A> =0A>This is my elevator angle with the airplane = in a forward C.G. condition (header fuel only, single pilot), flaps in ref= lex and, well, going as fast as an RV-7 will go in formation. :) =0A>http:= //www.n54sg.com/images/tuft_test_08.jpg=0A> =0A>=0A> =0A>So, this problem p= oses a few issues. =0A>First, this is obviously drag, probably a measurab= le amount thus for me the driving force behind correcting it one day. =A0S= econd is the available elevator travel. =A0If you read the manual, I have = the correct amount of up / down elevator travel. =A0But, if the photo is m= y starting point, it means I have much less up, and way too much down avai= lable to use. =A0The important part being the elevator up while in the fla= re. =A0Given a forward C.G. and a huge amount of flaps, this can be an iss= ue. (ask me how I know...) =0A>=0A> =0A>Next I would like to mention that n= ot all small tails trim the same. =A0Some use a spring system to bias the = entire elevator. =A0Others use trim tabs. =A0I have a tab that due to its = placement and odd elevator deflection has a limited functional envelope. = =A0Another driving force to change incidence. =0A>=0A> =0A>Now the often o= bvious question people ask is why haven't I fixed it yet. =A0Well, because= the job of fixing it is going to totally suck, and I wanted it to be the = last thing I do as my other aerodynamic changes may affect the angle of in= cidence. =A0This brings me to the next subject, what I have changed. =0A>= =0A> =0A>So I have this airplane going faster than most and figured why st= op now.. I made a rather drastic change that some call the beluga belly. = =A0It has been done to a few Legacys that race with varied applications of= the same idea. =A0Those familiar with the 320/360 fuselage will notice it= in this picture: =0A>http://www.n54sg.com/images/tuft_test_04.jpg=0A> =0A= >I'm working on a write up for my website detailing the project and its pu= rpose and will have that posted sometime soon. =A0But, I will report that = this did change the downwash on my horiztonal and did change my required a= ngle of incidence. Hence, I'm glad I waited to change that. =A0It actually= requires less up elevator than it did before so less negative incidence. = =A0The general theory is I have corrected some flow around the fuselage th= us making the entire horizontal a bit more effective. =A0Some modified Leg= acys experienced something similar. =A0I only wish it would have corrected= it more! =A0I now know more about this mod and maybe would have applied i= t differently. =A0Just not sure I'm willing to do the work again for unkno= wn gains. =0A>=0A> =0A>The other aerodynamic change I made (that relates = to the original stability post) is I removed the cusp from the bottom surf= ace of my flaps as suggested in a book about GA airfoils by Harry Riblett.= =A0Below is a simplified version of his drawing. =A0(Not accurate, just f= or explanation purposes) =A0The solid black is the modification. =0A>http:= //www.n54sg.com/images/Flap_Drawing.jpg=0A> =0A>So, what I have done to th= e camber of the wing is a bit odd I suppose, but it was odd to start with.= =A0Keep in mind, the 320 / 360 ailerons already have this modification. = =A0I didn't get the 10 kts I thought I would. =A0(Aren't all mods worth 10= kts? haha) =A0But, it is a different airfoil. =A0Stall was no different, = but the pitch force did increase with flaps extended. =A0Not a bad thing i= n my opinion. =A0Overall it is hard to explain, it is a different wing, ju= st can't pinpoint how.=A0 =0A>=0A> =0A>In the end I think I have made the = airplane aerodynamically better, but I have moved the problem. =A0It seems= with just a little bit cleaner airplane I ran in to the limit of the prop= eller. =A0Previously more rpm always netted more speed. =A0Now the top 250= ish rpm doesn't do much at all. =A0Total bummer! =A0Having to learn a lot = more about propellers than I ever thought I would now... =0A>=0A> =0A>Resu= lts of my airplane at Reno this year: =0A>Qualifying: 268.272 mph=0A>Spor= t Medallion: 1st 261.906 mph (only 2600 rpm!)=0A>Heat 1C: 3rd 268.300 mph= =0A>Heat 2C: 2nd 265.030 mph=0A>Heat 3C: 2nd 266.717 mph=0A>Bronze Race:= 2nd 266..944 mph=0A> =0A>=0A> =0A>I have some really cool video from my h= elmet/dash cameras, just trying to get it all edited. =A0Hear is a teaser = of some VERY close racing with Dave Morss in his Legacy: http://youtu.be/i= egd6ylVHI4 =0A>Best to watch in full screen in HD. =A0Keep in mind, object= s in a wide angle lens are closer than they appear! haha =0A>=0A> =0A>Tom = McNerney =0A>www.N54SG.com=A0 =0A>=0A>=0A>=0A> ---1977980688-632736007-1381099956=:26140 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Scott,
It sounds like you are mixing the terms for turbulent and separate= d flow.  They are definitely not the same.  Separated is ver= y bad while turbulent usually just adds drag.  Turbulent flow&nbs= p;is characterized by a mixing -and transfer of energy- between the st= ream lines.  Your smoke particles would have been quickly diluted in t= he air farther off the wing surface once the flow transitioned to turbulent= .  Truly separated flow over 40% of the wing would have had you fallin= g from the sky.
There should be no separation all th= e way to the trailing edge - the exception being the short span from wing t= railing edge to flap leading edge.  This is why the next surface = is sometimes placed just slightly higher than the preceding trailing edge and with a rounded leading edge.  It is meant to catch and reatt= ach the flow from the preceding surface.
You can see= flow separation on the upper surface of the flap at +10 degrees in TP-1865= once you hit about 5 degrees AoA.  Pressure recovery stops at that po= int on the surface.  In practice you see this while lowering the flaps= in rain.  At separation, the rain drops turn around and start running= forward on the upper surface of the flap. 
Tur= bulent flow can be coaxed back to laminar if there is a strong favorable pr= essure gradient accelerating the flow.  A bug right on the leadin= g edge is not as bad as one 6 inches back on the wing. 
<= div>If there is a separation problem, zigzag tape and vortex generato= rs can be used to energize the flow before it separates.  Once it sepa= rates, it is generally game over.  There are exceptions, but not directly applicable here. 
 
=
Chris Zavatson
N91CZ
360std
 
From: "Sky2high@aol.com" <Sky2high@aol.com>
To: lml@lancaironline.net
Sent: Sunday, October 6, 2013 7:31 AM<= br> Subject: [LML] Re: 320= /360 performance and stability

=0A
=0A=0A =0A =0A
=0A
Bill,
=0A
&= nbsp;
=0A
The intersection on the upper wing is crucial to the per= formance of the =0Awing in reflex.  Laminar flow on the properly = smooth upper wing =0Asurface is over 60% of the chord.  The reflexed p= ortion of the flap allows =0Afor re-attachment of the airflow and a reducti= on in drag. 
=0A
 
=0A
I have seen result= s of the laminar flow by flying through smokey air =0Aover the central stat= es in September (some years ago) with some bugs on the =0Aleading edge.&nbs= p; A stop in Boze on my way to the Labor Day factory fly in had =0Ame looki= ng down the wing into the setting sun whilst I was tying down.  I =0Ao= bserved smoke particle marked V's emanating from bugs obtained on take= off =0Ain Illinois and those V's easily extended back more than 60% of the = chord before =0Athere was separation.  If only I had taken pictures (u= h, this was before =0Adigital cameras in everyone's smart-ass phones) =
=0A
 
=0A
See the "Aerodynamics for Naval Aviators= " manual for the consequence of =0Awing dirtying particles being closer tog= ether than 1" resulting in loss of =0Alaminar flow.
=0A
 =0A
In another aircraft I had obtained a "dog-bone" cross sectio= n shaped =0A(along the chord) wooden prop that was more efficient and quiet= er than a more =0Anormal airfoil shaped prop.  Why?  Because the = separated air =0Areattached itself to the rise in the surface somewhat = ;after the mid =0Apoint.  
=0A
 
=0A
I bel= ieve the reflexed wing accomplishes a similar reattachment on the =0Aupper = surface.
=0A
 
=0A
Some builders may not treat the l= ower wing surface with proper respect in =0Athe area under the main spar wh= ere the D-section and the bottom skin are =0Ajoined.  It is crucial th= at this area be smooth (no waviness) because the =0Aflow attachment re= mains much further back than 60%.  Indeed, =0Athe concave sh= ape of the flap bottom may be important to the performance of the =0Awing w= hen at 0-reflex.  Those of us that were trying to achieve max speed = =0Adidn't really care whether the  wing performed efficiently at moder= ate =0Aspeeds ( I only considered two speeds - max cruise and approach to = =0Alanding).  Remember that one would prefer that the re-joined air at= the TE =0Ameet at the same speed so no additional TE drag is introduc= ed.
=0A
 
=0A
The aileron flat shape and squared off= 1/4" deep TE is similar to those =0Aseen on jets.  I believe this is = for increased control surface =0Aeffectiveness regardless of flap position.=   (BTW, I had mine =0Aboth rigged slightly higher than the -7 deg= rees reflex - a separate =0Adiscussion). 
=0A
 
=0A=
Anyway, perhaps flattening the bottom of the reflexed flap may re= duce =0Adrag - it would be interesting to see comparable before and af= ter =0Adata.
=0A
 
=0A
In the early days some people= tried zig-zag tape to try to re-attach air to =0Athe lower wing surface.&n= bsp; I don't think it was very successful.  Such =0Atape was used by g= lider folk for that purpose, but we are talking about =0Asignificantly diff= erent air speeds and probably different thickness boundary =0Alayers.
= =0A
 
=0A
The question would be if the drag induced by vo= rtex generators exciting =0Aseparated air would be less than the reduction = in drag created by an such an =0Aattempt to re-attach the air flow?  T= his as opposed to the change in the =0Aair flow at reflex by flattening the= bottom of the flap.
=0A
 
=0A
Hmmmmmm ............<= /div>=0A
 
=0A
Back to my rocking chair now .....
= =0A
 
=0A
Grayhawk
=0A
 
=0A
=0AIn a message dated 10/6/2013 7:45:10 A.M. Central Daylight Time, =0Awfha= nnahan@yahoo.com writes:
=0A
=0A
=0A

=0A
  =0A=

 Tom, thanks for sharing = your =0A work.

Just wondering if you,= or anyone else, =0A tried vortex generators in the concave wing/fuselage = intersection behind the =0A spar. The idea being to reduce drag by maintai= ning attached airflow in that =0A region without the big mod.

=0A
Regards,
=0A
Bill Hannahan
=0A <= div>
wfhannahan@yahoo.com
=0A

=0A
=0A =0A
=0A
=0A From: =0A "dudewanarace@yahoo.com" <dudewanarace@yahoo.com&= gt;
To: lml@lancaironli= ne.net
Sent: Wednesday= , October 2, 2013 5:49 =0A AM
Sub= ject: [LML] 320/360 =0A performance and stability
=0A

=0A
=0A
=0A
=0A
Readers,
=0A
I have =0A been watching this conversat= ion with interest.  I have some odd =0A experiences with stability in= my small tail 360 that was improperly built (not =0A by me).  Geez, = that is going to hurt resale.. haha
=0A

=0A
Anyway, =0A I ha= ve been waiting to comment as it will just fog the data that has been =0A = presented given my totally odd arrangement and lack of any real data. =0A =  All of my 'data' is seat of the pants, thus not worth mentioning. =0A=  But, figured I could expand on an envelope probably few have visite= d =0A just for interesting reading.
=0A

=0A
This =0A is my ele= vator angle with the airplane in a forward C.G. condition (header =0A fuel= only, single pilot), flaps in reflex and, well, going as fast as an RV-7 = =0A will go in formation. :)
=0A
http://www.n54sg.com= /images/tuft_test_08.jpg
=0A

=0A
So, this pr= oblem poses a few =0A issues.
=0A
First, this is obviously drag, probably a =0A measurable amo= unt thus for me the driving force behind correcting it one day. =0A  = Second is the available elevator travel.  If you read the manual, I = =0A have the correct amount of up / down elevator travel.  But, if th= e photo =0A is my starting point, it means I have much less up, and way to= o much down =0A available to use.  The important part being the eleva= tor up while in the =0A flare.  Given a forward C.G. and a huge amoun= t of flaps, this can be an =0A issue. (ask me how I know...)
= =0A

=0A
Next I would like to mention that not all= =0A small tails trim the same.  Some use a spring system to bias the= entire =0A elevator.  Others use trim tabs.  I have a tab that = due to its =0A placement and odd elevator deflection has a limited functio= nal envelope. =0A  Another driving force to change incidence.<= /div>=0A

=0A
Now =0A the often obvious question people ask is why ha= ven't I fixed it yet. =0A  Well, because the job of fixing it is goin= g to totally suck, and I =0A wanted it to be the last thing I do as my oth= er aerodynamic changes may affect =0A the angle of incidence.  This b= rings me to the next subject, what I have =0A changed.
=0A

= =0A
I'm =0A w= orking on a write up for my website detailing the project and its purpose a= nd =0A will have that posted sometime soon.  But, I will report that = this did =0A change the downwash on my horiztonal and did change my requir= ed angle of =0A incidence. Hence, I'm glad I waited to change that.  = It actually requires =0A less up elevator than it did before so less negat= ive incidence.  The =0A general theory is I have corrected some flow = around the fuselage thus making =0A the entire horizontal a bit more effec= tive.  Some modified Legacys =0A experienced something similar.  = ;I only wish it would have corrected it =0A more!  I now know more ab= out this mod and maybe would have applied it =0A differently.  Just n= ot sure I'm willing to do the work again for unknown =0A gains.
=0A =
=0A
The =0A other aerodynamic change I made (that relates to the orig= inal stability post) =0A is I removed the cusp from the bottom surface of = my flaps as suggested in a =0A book about GA airfoils by Harry Riblett. &n= bsp;Below is a simplified version =0A of his drawing.  (Not accurate,= just for explanation purposes)  The =0A solid black is the modificat= ion.
=0A
http://www.n54sg.com/images/Flap_Drawing.jpg
=0A So, =0A= what I have done to the camber of the wing is a bit odd I suppose, but it= was =0A odd to start with.  Keep in mind, the 320 / 360 ailerons alr= eady have =0A this modification.  I didn't get the 10 kts I thought I= would. =0A  (Aren't all mods worth 10 kts? haha)  But, it is a = different =0A airfoil.  Stall was no different, but the pitch force d= id increase with =0A flaps extended.  Not a bad thing in my opinion. =  Overall it is hard =0A to explain, it is a different wing, just can'= t pinpoint how. 
=0A

=0A
In =0A the end I think I have mad= e the airplane aerodynamically better, but I have =0A moved the problem. &= nbsp;It seems with just a little bit cleaner airplane I =0A ran in to the = limit of the propeller.  Previously more rpm always netted =0A more s= peed.  Now the top 250ish rpm doesn't do much at all.  Total =0A = bummer!  Having to learn a lot more about propellers than I ever thou= ght =0A I would now...
=0A

=0A
Results =0A of my airplane at R= eno this year:
=0A
Qualifying: =0A 268.272 mph
Sport =0A Medallion: 1st 261.906 mph (only = 2600 rpm!)
H= eat =0A 1C: 3rd 268.300 mph
Heat =0A 2C: 2nd 265.030 mph
Heat =0A 3C: 2nd 266.717 mph
Bronze =0A Race: 2nd = 266..944 mph
=0A

=0A
I =0A have some really cool vid= eo from my helmet/dash cameras, just trying to get it =0A all edited. &nbs= p;Hear is a teaser of some VERY close racing with Dave Morss =0A in his Le= gacy: http://youtu.be/iegd6ylVHI4
=0A
Best =0A to watch in full screen = in HD.  Keep in mind, objects in a wide angle =0A lens are closer tha= n they appear! haha
=0A

=0A
Tom =0A McNerney
=0A
www.N54SG.c= om 
=0A





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