X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 30 Jun 2011 19:10:15 -0400 Message-ID: X-Original-Return-Path: Received: from [198.64.152.110] (HELO sdc.com) by logan.com (CommuniGate Pro SMTP 5.4.0) with ESMTP id 5038662 for lml@lancaironline.net; Thu, 30 Jun 2011 15:32:40 -0400 Received-SPF: pass receiver=logan.com; client-ip=198.64.152.110; envelope-from=Ronald@sdc.com Received: from [192.168.0.14] [68.202.59.0] by sdc.com with ESMTP (SMTPD-11.5) id f6cc00035e28bf8e; Thu, 30 Jun 2011 15:22:29 -0400 User-Agent: Microsoft-MacOutlook/14.0.0.100825 X-Original-Date: Thu, 30 Jun 2011 15:32:01 -0400 Subject: Re: [LML] Re: Ventral Strakes, do they reduce performance? From: Ronald STEVENS X-Original-To: Lancair Mailing List X-Original-Message-ID: Thread-Topic: [LML] Re: Ventral Strakes, do they reduce performance? In-Reply-To: Mime-version: 1.0 Content-type: multipart/alternative; boundary="B_3392292725_9759445" > This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --B_3392292725_9759445 Content-type: text/plain; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable Hi Jack Thanks for the explanations, I have the Tru-Trak sorcerer installed in my plane and was planning the Yaw damper as it is said that the 4p changes yaw with every speed change, so I am assuming the yaw damper together with the auto trim would correct this issue, right? =3D=3D Ronald From: J H Webb Reply-To: Lancair Mailing List Date: Thu, 30 Jun 2011 15:06:20 -0400 To: Subject: [LML] Re: Ventral Strakes, do they reduce performance? 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 Ventra= l fins on several LIV's. The need is much greater for the LIV-PT but there is an improvement in both 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 Ventral fin taht are used on several LIV-PT's. 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. On the question about yaw 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 currently are on limited value plus the current units that connect directly to the rudder increase the rudder friction band significantly making the airplane more difficult to master yaw control. The ideal installation would a unit operating a separate control surface such a= s the trailing edge of the ventral fin. Jack Webb L360, LIV=20 AeroSpace Engineer BSAE FAA Designated Check airman for C421, C404 & C310 ATP, CFI Airplanes & Instruments, Multi, & Sea Numerous Jet Type Ratings Experienced Experimental Test Pilot both multi and single engine aircraft Former Chief Engineering Test Pilot for a Major Manufacturer Corporate Chief Pilot for Construction company Ohio Flying is the perfect vocation for a man who wants to feel like a boy, but not for one who still is. From: RONALD STEVENS To: lml@lancaironline.net Sent: Monday, June 27, 2011 7:34 AM Subject: [LML] Ventral Strakes, do they reduce performance? Hello guys Me again, I just 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. 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 turbulence, go-arrounds, full power take offs as well. My very near future plane (we are almost closing ;) is a newer one, so the 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?=20 Thanks =8B Ronald Stevens (Cirrus 1100 hours, Velocity 250 hours, Lancair 4p student now with 1 hour LOL) =20 --B_3392292725_9759445 Content-type: text/html; charset="ISO-8859-1" Content-transfer-encoding: quoted-printable
Hi Jack

=
Thanks for the explanations, I have the Tru-Trak sorcerer instal= led in my plane and was planning the Yaw damper as it is said that the 4p ch= anges yaw with every speed change, so I am assuming the yaw damper togeth= er with the auto trim would correct this issue, right?

=3D=3D Ronald

From: J H Webb <airmale4@yahoo.com&= gt;
Reply-To: Lancair Mailing List= <lml@lancaironline.net>Date: Thu, 30 Jun 2011 15:06:20 -040= 0
To: <lml@lancaironline.net>
Subject: [LML] Re: Ventral Strakes, do they reduce performance?

Ro= n,

    Sor= ry it has taken so long but I have been busy. You have asked several questio= ns, and on the question of Ventral fins, I have had installed Ventral fins o= n several LIV's. The need is much greater for the LIV-PT but there is an imp= rovement in both 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 Ventral fin taht are used on several LIV-PT's.
 = Clark Still's aircraft is a good example of a PT with the single fin Ventra= l fin, on that airplane we made a very significant improvement in directiona= l stability.
     On the question about = yaw 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 to= the rudder increase the rudder friction band significantly making the airpl= ane more difficult to master yaw control. The ideal installation would a uni= t operating a separate control surface such as the trailing edge of the vent= ral fin.

Jack Webb
L360, LIV
AeroSpace Engineer BSAE
FAA Designated Check airman for C421, C404 & C310
ATP, CFI Airplanes & Instruments, Multi, & Sea
Numerous Jet Type Ratings
Experienced Experimental Test Pilot both multi and single engine aircraft Former Chief Engineering Test Pilot for a Major Manufacturer
Corporate Chief Pilot for Constructi= on company
Ohio

Flying is the pe= rfect vocation for a man who wants to feel like a boy, but not for one who still is.

From: RONALD STEVENS <ronald@sdc.com&= gt;
To: lml@lancaironline.net
Sent: Monday, June 27, 2011 7:34 AM
Subject: [LML] Ventral Strakes, do they reduc= e performance?

Hello guys

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

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

My very near future plane (we ar= e almost closing ;) is a newer one, so the 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 an= d I was already thinking of installing the Yaw damper (I have the tru-trak s= orcerer) and perhaps also installing those Ventral strakes.

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

Thanks — Ronald Stevens (Cirrus 1100 hours, Velocity 250 hours, = Lancair 4p student now with 1 hour LOL)


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