X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 30 Jun 2011 15:06:20 -0400 Message-ID: X-Original-Return-Path: Received: from nm24-vm0.bullet.mail.ac4.yahoo.com ([98.139.53.222] verified) by logan.com (CommuniGate Pro SMTP 5.4.0) with SMTP id 5038409 for lml@lancaironline.net; Thu, 30 Jun 2011 11:03:15 -0400 Received-SPF: none receiver=logan.com; client-ip=98.139.53.222; envelope-from=airmale4@yahoo.com Received: from [98.139.52.188] by nm24.bullet.mail.ac4.yahoo.com with NNFMP; 30 Jun 2011 15:02:41 -0000 Received: from [98.139.52.175] by tm1.bullet.mail.ac4.yahoo.com with NNFMP; 30 Jun 2011 15:02:41 -0000 Received: from [127.0.0.1] by omp1058.mail.ac4.yahoo.com with NNFMP; 30 Jun 2011 15:02:41 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 659835.11912.bm@omp1058.mail.ac4.yahoo.com Received: (qmail 14251 invoked by uid 60001); 30 Jun 2011 15:02:41 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=Jiq1ex/4f/0/4T7xWbk+eANr2hU1Ex9abFqz47iNHfsNfd75PquYvcc72DrylVTZ3nNxeACEFVj1JbjJYm9D06YknXqMS2ZVpuDYOe5VyquLuJRzE64/ZrIdO6c0DirJda3YHOCuySUYk4zVe5NqTxzaZmoNjXCnh+r/uDM96DI=; X-YMail-OSG: DDYEBo4VM1kftV5v02dsp9fUgKcJyLy9mkQWccLOvAYnGIW XXKA_VaWSEwhz0qBr93f_LSSXQseBu8Zy9HDNaeCU60qtWh_pJhJ90VKPBAh cGKTxLVXGVBaf.GSS6CQbHwthZekcBIRfB2nNRyYTNQbyhNJ.CZxdOnsYKoA ACzSUvbkvWL2LUWOowzYrh2cbW2.HDOoFVNQpmw78DP0eo8e0bBAwv0Ww3Uy Tl2sERmxi8YJG.t.vaVbdHcX.2kHYNVmpUx3K5MfaOqjv9d0fcUKZcRZZ6eb 18oDuPaBmw31_Hw5vgvX81Agu1S0JJwQZH.Knr0FOPfzxRtQrxOPKEWpwLRC zWAr72kG3xibVLW6clPCGPiD1VXZ22MZ_ImYooiO8vLziuSUTFKfIX3_KIL_ iOlUzdZ5p5kbtiQ-- Received: from [75.88.112.162] by web65804.mail.ac4.yahoo.com via HTTP; Thu, 30 Jun 2011 08:02:41 PDT X-Mailer: YahooMailWebService/0.8.112.307740 References: X-Original-Message-ID: <1309446161.10813.YahooMailNeo@web65804.mail.ac4.yahoo.com> X-Original-Date: Thu, 30 Jun 2011 08:02:41 -0700 (PDT) From: J H Webb Reply-To: J H Webb Subject: Re: [LML] Ventral Strakes, do they reduce performance? X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-403180645-1309446161=:10813" --0-403180645-1309446161=:10813 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Ron,=0A=0A=C2=A0=C2=A0=C2=A0 Sorry it has taken so long but I have been bus= y. You have asked several questions, and on the question of Ventral fins, I= have had installed Ventral fins on several LIV's. The need is much greater= for the LIV-PT but there is an improvement in both piston and turbine mode= ls. The little dual fins are not as effective as one larger single fin. Plu= s the drag seems to be lower. I have designed a single fin shape that works= well, no noticeable impact on cruise speed.=0AI did notice a slight speed = reduction with the twin Ventral fin taht are used on several LIV-PT's.=0A= =0A=C2=A0 Clark Still's aircraft is a good example of a PT with the single = fin Ventral fin, on that airplane we made a very significant improvement in= directional stability.=0A=C2=A0=C2=A0=C2=A0=C2=A0 On the question about ya= w dampers, the yaw damper is very helpful when it is a high frequency unit = with no feedback in the rudders. Unfortunately hte yaw dampers available cu= rrently are on limited value plus the current units that connect directly t= o the rudder increase the rudder friction band significantly making the air= plane more difficult to master yaw control. The ideal installation would a = unit operating a separate control surface such as the trailing edge of the = ventral fin.=0A=0AJack Webb=0AL360, LIV =0AAeroSpace Engineer BSAE =0AFAA D= esignated Check airman for C421, C404 & C310=0AATP, CFI Airplanes & Instrum= ents, Multi, & Sea=0ANumerous Jet Type Ratings=0AExperienced Experimental T= est Pilot both multi and single engine aircraft=0AFormer Chief Engineering = Test Pilot for a Major Manufacturer=0ACorporate Chief Pilot for Constructio= n=0Acompany=0AOhio=0A=0AFlying is the perfect vocation=0Afor a man who want= s to feel like a boy, but not for one who still is.=0A=0A=0A_______________= _________________=0AFrom: RONALD STEVENS =0ATo: lml@lancair= online.net=0ASent: Monday, June 27, 2011 7:34 AM=0ASubject: [LML] Ventral S= trakes, do they reduce performance?=0A=0A=0AHello guys=0A=0AMe again, I jus= t had my first lesson with the Lancair 4p (with JC) and when I took off the= plane was wiggling its tail like a happy dog LOL Nothing scary, but this I= can imagine could be annoying for passengers.=0A=0ANow I was looking on th= e internet and found that=C2=A0Ventral Strakes =C2=A0were used to fight aga= inst those 'yaw' effects.=0AIt suppose to help with turbulence, go-arrounds= , full power take offs as well.=0A=0AMy very near future plane (we are almo= st closing ;) is a newer one, so the tail section was already updated to th= e latest.=C2=A0=0A=0ABut looking at my passengers (I fly with my Son and Gi= rlfriend a lot) this could be disturbing for them and I was already thinkin= g of installing the Yaw damper (I have the tru-trak sorcerer) and perhaps a= lso installing those Ventral strakes.=0A=0ADoes anybody have experience (be= fore and after) with those? And would you recommend those?=C2=A0=0A=0AThank= s =E2=80=94 Ronald Stevens (Cirrus 1100 hours, Velocity 250 hours, Lancair = 4p student now with 1 hour LOL) --0-403180645-1309446161=:10813 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Ron,

    Sorry it has taken = so long but I have been busy. You have asked several questions, and on the = question of Ventral fins, I have had installed Ventral fins on several LIV'= s. The need is much greater for the LIV-PT but there is an improvement in b= oth piston and turbine models. The little dual fins are not as effective as= one larger single fin. Plus the drag seems to be lower. I have designed a = single fin shape that works well, no noticeable impact on cruise speed.
I did notice a slight speed reduction with the twin Ven= tral fin taht are used on several LIV-PT's.
  Clark S= till's aircraft is a good example of a PT with the single fin Ventral fin, = on that airplane we made a very significant improvement in directional stability.
     On the question about = yaw dampers, the yaw damper is very helpful when it is a high frequency uni= t with no feedback in the rudders. Unfortunately hte yaw dampers available = currently are on limited value plus the current units that connect directly= to the rudder increase the rudder friction band significantly making the a= irplane more difficult to master yaw control. The ideal installation would = a unit operating a separate control surface such as the trailing edge of th= e ventral fin.

=0A=0A
Jack Webb
=0AL360, LIV
=0A=0A
= AeroSpace Engineer BSAE
=0AFAA Designated Check airman for C421, C404= & C310
=0AATP, CFI Airplanes & Instruments, Multi, & Sea=0ANumerous Jet Type Ratings
=0AExperienced Experimental Test Pilot bot= h multi and single engine aircraft
=0AFormer Chief Engineering Test Pilo= t for a Major Manufacturer
=0A=0A
<= span style=3D"font-size:10.0pt">Corporate Chief Pilot for Construction=0Aco= mpany
=0AOhio
=0A=0A

=0A=0A
Flying is the perfect vocation=0Afor a man who = wants to feel like a boy, but not for one who still is.
=0A=0A

From: RONALD STEVENS <ronald@sdc.com>
To: lml@lancaironline.net
Sent: Monday, June 27, 2011 7:34 AMSubject: [LML] Ventral S= trakes, do they reduce performance?

=0A
Hello guys

Me again, I just had my first = lesson with the Lancair 4p (with JC) and when I took off the plane was wigg= ling its tail like a happy dog LOL Nothing scary, but this I can imagine co= uld be annoying for passengers.

Now I was looking = on the internet and found that Ventral Strakes  were used = to fight against those 'yaw' effects.
It suppose to help with tur= bulence, go-arrounds, full power take offs as well.

My very near future plane (we are almost closing ;) is a newer one, so th= e tail section was already updated to the latest. 

But looking at my passengers (I fly with my Son and Girlfriend a lot)= this could be disturbing for them and I was already thinking of installing= the Yaw damper (I have the tru-trak sorcerer) and perhaps also installing = those Ventral strakes.

Does anybody have experience (before and= after) with those? And would you recommend those? 

Thanks =E2=80=94 Ronald Stevens (Cirrus 1100 hours, Velocity 250 hou= rs, Lancair 4p student now with 1 hour LOL)
=0A


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