X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 12 Oct 2013 18:59:15 -0400 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122] verified) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTP id 6511565 for lml@lancaironline.net; Fri, 11 Oct 2013 10:58:18 -0400 Received-SPF: none receiver=logan.com; client-ip=71.74.56.122; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: X-Authority-Analysis: v=2.0 cv=e9iEuNV/ c=1 sm=0 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=3Zlka_XeuxsA:10 a=iIqlaGweKFIA:10 a=ttCsPuSJ-FAA:10 a=rTjvlri0AAAA:8 a=KGjhK52YXX0A:10 a=5XGz6UvgYSsA:10 a=Ia-xEzejAAAA:8 a=CjxXgO3LAAAA:8 a=ndVRne3UAAAA:8 a=5FIZSGrRAAAA:8 a=Aj82RSfrAAAA:8 a=-uLxOpdrAAAA:8 a=jJrOw3FHAAAA:8 a=EhIAmuiZtXb333tB0qwA:9 a=wPNLvfGTeEIA:10 a=nDfyusUNnaUA:10 a=EzXvWhQp4_cA:10 a=rC2wZJ5BpNYA:10 a=YQ-GvmYU9tsA:10 a=FU4QsWcZpzsA:10 a=NWVoK91CQyQA:10 a=SSmOFEACAAAA:8 a=yMhMjlubAAAA:8 a=zY15FjwFJgQwGbhekeQA:9 a=gKO2Hq4RSVkA:10 a=_W_S_7VecoQA:10 a=jzrxcrKw4anAgYac:21 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:1365] helo=lobo) by hrndva-oedge04.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id C4/23-11626-6E118525; Fri, 11 Oct 2013 14:57:42 +0000 X-Original-Message-ID: From: "Wolfgang" X-Original-To: References: Subject: Re: [LML] 320/360 performance and stability X-Original-Date: Fri, 11 Oct 2013 10:57:35 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0164_01CEC670.B1840860" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5512 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5512 This is a multi-part message in MIME format. ------=_NextPart_000_0164_01CEC670.B1840860 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable You're flying with up-elevator but the trim spring is pushing forward ? = ? That does not compute . . .=20 Wolfgang ----- Original Message -----=20 From: Craig Schulze=20 To: lml@lancaironline.net=20 Sent: Thursday, October 10, 2013 8:37 AM Subject: RE: [LML] 320/360 performance and stability Hi Chris, =20 Since I have upgraded from 320 to 360 my airplane is now on the = forward side of its CG range. It's nice now when I throw a few things = in the back. Since this discussion all came up I looked at my elevator = in flight and it is clearly is flying in an up elevator condition even = though the trim spring is trying to push the stick forward to keep level = flight. That is why I was thinking that a little reduced down thrust = may not have the tail fighting so much to keep everything in balance for = level flight. Don't have room to do much but wondering it that would = help put the elevator in more of a neutral position. =20 Craig Schulze N73S =20 From: Chris Zavatson [mailto:chris_zavatson@yahoo.com]=20 Sent: Tuesday, October 08, 2013 4:55 AM To: lml@lancaironline.net Subject: Re: [LML] 320/360 performance and stability =20 Craig, "I was thinking about reducing engine downthrust. Any thoughts on = this Chris?" =20 Less downthrust is destabilizing. =20 If you are going to change downthrust, I would love to record your = neutral point before and after. It is rare to get stability data on a = propeller changes like this. =20 Here is paper that discusses the stability changes to the Hawkeye E-2C = simply by increasing prop disc solidity. Four blade to eight blade = prop. http://n91cz.com/Interesting_Technical_Reports/E2_prop_change.pdf Chris Zavatson N91CZ 360std http://www.n91cz.net/ =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 =20 ------=_NextPart_000_0164_01CEC670.B1840860 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
You're flying with up-elevator but the = trim spring=20 is pushing forward ? ?
 
That does not compute . . . =
 
Wolfgang
 
----- Original Message -----
From:=20 Craig = Schulze=20
Sent: Thursday, October 10, = 2013 8:37=20 AM
Subject: RE: [LML] 320/360 = performance=20 and stability

Hi=20 Chris,

 

Since=20 I have upgraded from 320 to 360 my airplane is now on the forward side = of its=20 CG range.  It's nice now when I throw a few things in the = back. =20 Since this discussion all came up I looked at my elevator in flight = and it is=20 clearly is flying in an up elevator condition even though the trim = spring is=20 trying to push the stick forward to keep level flight.  That is = why I was=20 thinking that a little reduced down thrust may not have the tail = fighting so=20 much to keep everything in balance for level flight.  Don=92t = have room to=20 do much but wondering it that would help put the elevator in more of a = neutral=20 position.

 

Craig=20 Schulze

N73S

 

From: Chris = Zavatson=20 [mailto:chris_zavatson@yahoo.com]
Sent: Tuesday, October = 08, 2013=20 4:55 AM
To: lml@lancaironline.net
Subject: Re: = [LML]=20 320/360 performance and stability

 

Craig,

"I was=20 thinking about reducing engine downthrust.  Any thoughts on this=20 Chris?"

 

Less = downthrust is=20 destabilizing. 

If you = are going=20 to change downthrust, I would love to record your neutral point = before=20 and after.  It is rare to get stability data on a propeller = changes like=20 this.

 

Here is = paper that=20 discusses the stability changes to the Hawkeye E-2C simply by = increasing prop=20 disc solidity.  Four blade to eight blade prop.

 http://n91cz.com/Interesting_Technical_Reports/E2_prop_change.pdf

Chris=20 Zavatson

N91CZ

360std

http://www.n91cz.net/

 

From: Craig = Schulze=20 [mailto:craig@skybolt.net]
Sent: Thursday, October 03, 2013 = 1:04=20 PM
To:=20 'dudewanarace@yahoo.com'
Subject: RE: 320/360 performance = and=20 stability

 

Hi=20 Tom,

 

What type = of odd=20 experiences are you having with yours?  I have been noticing that = the=20 faster I go the more pitch sensitive it is. I  have the small = tail too=20 and my elevator position is about the same as yours in cruise.  I = was=20 thinking about reducing engine downthrust.  Any thoughts on this=20 Chris?

 

What were = the results=20 of flattening the bottom of the flaps?  Any speed=20 gain?

 

Craig

Small = tail 360=20 N73S

 

 

From: = dudewanarace@yahoo.com=20 [mailto:dudewanarace@yahoo.com]
Sent:=20 Wednesday, October 02, 2013 4:50 AM
To: = lml@lancaironline.net
Subject: 320/360 performance and=20 stability

 

Readers,

I have been = watching=20 this conversation with interest.  I have some odd experiences = with=20 stability in my small tail 360 that was improperly built (not by me).=20  Geez, that is going to hurt resale.. haha

 

Anyway, I = have been=20 waiting to comment as it will just fog the data that has been = presented given=20 my totally odd arrangement and lack of any real data.  All of my = 'data'=20 is seat of the pants, thus not worth mentioning.  But, figured I = could=20 expand on an envelope probably few have visited just for interesting=20 reading.

 

This is my = elevator=20 angle with the airplane in a forward C.G. condition (header fuel only, = single=20 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

 

So, this = problem poses=20 a few issues.

First, this = is=20 obviously drag, probably a measurable amount thus for me the driving = force=20 behind correcting it one day.  Second is the available elevator = travel.=20  If you read the manual, I have the correct amount of up / down = elevator=20 travel.  But, if the photo is my starting point, it means I have = much=20 less up, and way too much down available to use.  The important = part=20 being the elevator up while in the flare.  Given a forward C.G. = and a=20 huge amount of flaps, this can be an issue. (ask me how I=20 know...)

 

Next I = would like to=20 mention that not all small tails trim the same.  Some use a = spring system=20 to bias the entire elevator.  Others use trim tabs.  I have = a tab=20 that due to its placement and odd elevator deflection has a limited = functional=20 envelope.  Another driving force to change = incidence.

 

Now the = often obvious=20 question people ask is why haven't I fixed it yet.  Well, because = the job=20 of fixing it is going to totally suck, and I wanted it to be the last = thing I=20 do as my other aerodynamic changes may affect the angle of incidence.=20  This brings me to the next subject, what I have=20 changed.

 

So I have = this airplane=20 going faster than most and figured why stop now.. I made a rather = drastic=20 change that some call the beluga belly.  It has been done to a = few=20 Legacys that race with varied applications of the same idea. =  Those=20 familiar with the 320/360 fuselage will notice it in this=20 picture:

http://www.n54sg.com/images/tuft_test_04.jpg

I'm working = on a write=20 up for my website detailing the project and its purpose and will have = that=20 posted sometime soon.  But, I will report that this did change = the=20 downwash on my horiztonal and did change my required angle of = incidence.=20 Hence, I'm glad I waited to change that.  It actually requires = less up=20 elevator than it did before so less negative incidence.  The = general=20 theory is I have corrected some flow around the fuselage thus making = the=20 entire horizontal a bit more effective.  Some modified Legacys=20 experienced something similar.  I only wish it would have = corrected it=20 more!  I now know more about this mod and maybe would have = applied it=20 differently.  Just not sure I'm willing to do the work again for = unknown=20 gains.

 

The other = aerodynamic=20 change I made (that relates to the original stability post) is I = removed the=20 cusp from the bottom surface of my flaps as suggested in a book about = GA=20 airfoils by Harry Riblett.  Below is a simplified version of his = drawing.=20  (Not accurate, just for explanation purposes)  The solid = black is=20 the modification.

http://www.n54sg.com/images/Flap_Drawing.jpg

So, what I = have done to=20 the camber of the wing is a bit odd I suppose, but it was odd to start = with.=20  Keep in mind, the 320 / 360 ailerons already have this = modification.=20  I didn't get the 10 kts I thought I would.  (Aren't all = mods worth=20 10 kts? haha)  But, it is a different airfoil.  Stall was no = different, but the pitch force did increase with flaps extended. =  Not a=20 bad thing in my opinion.  Overall it is hard to explain, it is a=20 different wing, just can't pinpoint how. 

 

In the end = I think I=20 have made the airplane aerodynamically better, but I have moved the = problem.=20  It seems with just a little bit cleaner airplane I ran in to the = limit=20 of the propeller.  Previously more rpm always netted more speed.=20  Now the top 250ish rpm doesn't do much at all.  Total = bummer!=20  Having to learn a lot more about propellers than I ever thought = I would=20 now...

 

Results of = my airplane=20 at Reno this year:

Qualifying: 268.272=20 mph
Sport Medallion: 1st 261.906 mph (only = 2600=20 rpm!)
Heat 1C: 3rd = 268.300=20 mph
Heat 2C: 2nd 265.030 = mph
Heat 3C: 2nd 266.717 = mph
Bronze Race: 2nd = 266..944=20 mph

 

I have some = really cool=20 video from my helmet/dash cameras, just trying to get it all edited.=20  Hear is a teaser of some VERY close racing with Dave Morss in = his=20 Legacy: http://youtu.be/iegd6ylVHI4

Best to = watch in full=20 screen in HD.  Keep in mind, objects in a wide angle lens are = closer than=20 they appear! haha

 

Tom=20 McNerney

www.N54SG.com 

 

 

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