X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 04 Oct 2013 09:42:02 -0400 Message-ID: X-Original-Return-Path: Received: from mta31.charter.net ([216.33.127.82] verified) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTP id 6502173 for lml@lancaironline.net; Fri, 04 Oct 2013 09:00:48 -0400 Received-SPF: pass receiver=logan.com; client-ip=216.33.127.82; envelope-from=troneill@charter.net Received: from imp09 ([10.20.200.9]) by mta31.charter.net (InterMail vM.8.01.05.02 201-2260-151-103-20110920) with ESMTP id <20131004130014.MCOI24708.mta31.charter.net@imp09> for ; Fri, 4 Oct 2013 09:00:14 -0400 Received: from [192.168.2.3] ([75.132.162.230]) by imp09 with smtp.charter.net id Z10D1m00S4yZwCz0510DTC; Fri, 04 Oct 2013 09:00:14 -0400 X-Authority-Analysis: v=2.0 cv=ZL6PAgHb c=1 sm=1 a=SmX8XOgDoNe7CI0pWN500A==:17 a=iIqlaGweKFIA:10 a=yUnIBFQkZM0A:10 a=hOpmn2quAAAA:8 a=5XGz6UvgYSsA:10 a=Aj82RSfrAAAA:8 a=CjxXgO3LAAAA:8 a=Ia-xEzejAAAA:8 a=-uLxOpdrAAAA:8 a=jJrOw3FHAAAA:8 a=Yfdg1pDy0dJ-Mok9XiIA:9 a=CjuIK1q_8ugA:10 a=YQ-GvmYU9tsA:10 a=rC2wZJ5BpNYA:10 a=EzXvWhQp4_cA:10 a=FU4QsWcZpzsA:10 a=NWVoK91CQyQA:10 a=H4zDME6SaB_ecqyRGdIA:9 a=_W_S_7VecoQA:10 a=LI_3iS5MvWCow3W1:21 a=SmX8XOgDoNe7CI0pWN500A==:117 From: Terrence O'Neill Mime-Version: 1.0 (Apple Message framework v1085) Content-Type: multipart/alternative; boundary=Apple-Mail-12-1004971675 Subject: Re: [LML] 320/360 performance and stability X-Original-Date: Fri, 4 Oct 2013 08:00:13 -0500 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: <9F47F30A-E246-4ACD-B408-9DA6BA8117E6@charter.net> X-Mailer: Apple Mail (2.1085) --Apple-Mail-12-1004971675 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Hi Craig. Terrence lurking here... one of the basic factors in pitch stability is = a forward CG location. The more forward a CG is, the more pitch-stable = it is... and the tradeoff is is more up-elevator is required for the = balance. Terrence N211AL 235/320 On Oct 3, 2013, at 3:37 PM, Craig Schulze wrote: > =20 > =20 > From: Craig Schulze [mailto:craig@skybolt.net]=20 > Sent: Thursday, October 03, 2013 1:04 PM > To: 'dudewanarace@yahoo.com' > Subject: RE: 320/360 performance and stability > =20 > Hi Tom, > =20 > What type of odd experiences are you having with yours? I have been = noticing that the faster I go the more pitch sensitive it is. I have = the small tail too and my elevator position is about the same as yours = in cruise. I was thinking about reducing engine downthrust. Any = thoughts on this Chris? > =20 > What were the results of flattening the bottom of the flaps? Any = speed gain? > =20 > Craig > Small tail 360 N73S > =20 > =20 > From: dudewanarace@yahoo.com [mailto:dudewanarace@yahoo.com]=20 > Sent: Wednesday, October 02, 2013 4:50 AM > To: lml@lancaironline.net > Subject: 320/360 performance and stability > =20 > Readers, > I have been watching this conversation with interest. I have some odd = experiences with stability in my small tail 360 that was improperly = built (not by me). Geez, that is going to hurt resale.. haha > =20 > Anyway, I have been waiting to comment as it will just fog the data = that has been presented given my totally odd arrangement and lack of any = real data. All of my 'data' is seat of the pants, thus not worth = mentioning. But, figured I could expand on an envelope probably few = have visited just for interesting reading. > =20 > This is my elevator angle with the airplane in a forward C.G. = condition (header fuel only, single pilot), flaps in reflex and, well, = going as fast as an RV-7 will go in formation. :) > http://www.n54sg.com/images/tuft_test_08.jpg > =20 > So, this problem poses a few issues. > First, this is obviously drag, probably a measurable amount thus for = me the driving force behind correcting it one day. Second is the = available elevator travel. If you read the manual, I have the correct = amount of up / down elevator travel. But, if the photo is my starting = point, it means I have much less up, and way too much down available to = use. The important part being the elevator up while in the flare. = Given a forward C.G. and a huge amount of flaps, this can be an issue. = (ask me how I know...) > =20 > Next I would like to mention that not all small tails trim the same. = Some use a spring system to bias the entire elevator. Others use trim = tabs. I have a tab that due to its placement and odd elevator = deflection has a limited functional envelope. Another driving force to = change incidence. > =20 > Now the often obvious question people ask is why haven't I fixed it = yet. Well, 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 incidence. This brings me to the next subject, what = I have changed. > =20 > So I have this airplane going faster than most and figured why stop = now.. I made a rather drastic change that some call the beluga belly. = It has been done to a few Legacys that race with varied applications of = the same idea. Those familiar with the 320/360 fuselage will notice it = in this picture: > http://www.n54sg.com/images/tuft_test_04.jpg > I'm working on a write up for my website detailing the project and its = purpose and will have that posted sometime soon. But, I will report = that this did change the downwash on my horiztonal and did change my = required angle of incidence. Hence, I'm glad I waited to change that. = It actually requires less up elevator than it did before so less = negative incidence. The general theory is I have corrected some flow = around the fuselage thus making the entire horizontal a bit more = effective. Some modified Legacys experienced something similar. I only = wish it would have corrected it more! I now know more about this mod = and maybe would have applied it differently. Just not sure I'm willing = to do the work again for unknown gains. > =20 > The other aerodynamic change I made (that relates to the original = stability post) is I removed the cusp from the bottom surface of my = flaps as suggested in a book about GA airfoils by Harry Riblett. Below = is a simplified version of his drawing. (Not accurate, just for = explanation purposes) The solid black is the modification. > http://www.n54sg.com/images/Flap_Drawing.jpg > So, what I have done to the camber of the wing is a bit odd I suppose, = but it was odd to start with. Keep in mind, the 320 / 360 ailerons = already have this modification. I didn't get the 10 kts I thought I = would. (Aren't all mods worth 10 kts? haha) But, it is a different = airfoil. Stall was no different, but the pitch force did increase with = flaps extended. Not a bad thing in my opinion. Overall it is hard to = explain, it is a different wing, just can't pinpoint how.=20 > =20 > In the end I think I have made the airplane aerodynamically better, = but I have moved the problem. It seems with just a little bit cleaner = airplane I ran in to the limit of the propeller. Previously more rpm = always netted more speed. Now the top 250ish rpm doesn't do much at = all. Total bummer! Having to learn a lot more about propellers than I = ever thought I would now... > =20 > Results of my airplane at Reno this year: > Qualifying: 268.272 mph > Sport Medallion: 1st 261.906 mph (only 2600 rpm!) > Heat 1C: 3rd 268.300 mph > Heat 2C: 2nd 265.030 mph > Heat 3C: 2nd 266.717 mph > Bronze Race: 2nd 266..944 mph > =20 > I have some really cool video from my helmet/dash cameras, just trying = to get it all edited. Hear is a teaser of some VERY close racing with = Dave Morss in his Legacy:http://youtu.be/iegd6ylVHI4 > Best to watch in full screen in HD. Keep in mind, objects in a wide = angle lens are closer than they appear! haha > =20 > Tom McNerney > www.N54SG.com=20 > =20 --Apple-Mail-12-1004971675 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii Hi Craig.

Terrence lurking here... =  one of the basic factors in pitch stability is a forward CG = location.  The more forward a CG is, the more pitch-stable it is... = and the tradeoff is is more up-elevator is required for the = balance.

Terrence
N211AL = 235/320

On Oct 3, 2013, at 3:37 PM, Craig = Schulze wrote:

From: Craig Schulze = [mailto:craig@skybolt.net] 
Sent: Thursday, October 03, 2013 = 1:04 PM
To:  RE: 320/360 performance and = stability
Hi = Tom,
What = type of odd experiences are you having with yours?  I have been = noticing that the faster I go the more pitch sensitive it is. I =  have the small tail too and my elevator position is about the same = as yours in cruise.  I was thinking about reducing engine = downthrust.  Any thoughts on this = Chris?
What = were the results of flattening the bottom of the flaps?  Any speed = gain?
Small = tail 360 N73S
From: dudewanarace@yahoo.com [mailto:dudewanarace@yahoo.co= m] 
Sent: Wednesday, October 02, = 2013 4:50 AM
To:  320/360 performance and = stability
 

= --Apple-Mail-12-1004971675--