X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 12 Aug 2010 08:20:16 -0400 Message-ID: X-Original-Return-Path: Received: from imr-ma02.mx.aol.com ([64.12.206.40] verified) by logan.com (CommuniGate Pro SMTP 5.3.8) with ESMTP id 4427521 for lml@lancaironline.net; Wed, 11 Aug 2010 20:50:15 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.206.40; envelope-from=Sky2high@aol.com Received: from imo-ma04.mx.aol.com (imo-ma04.mx.aol.com [64.12.78.139]) by imr-ma02.mx.aol.com (8.14.1/8.14.1) with ESMTP id o7C0nUHq029315 for ; Wed, 11 Aug 2010 20:49:30 -0400 Received: from Sky2high@aol.com by imo-ma04.mx.aol.com (mail_out_v42.9.) id q.ef6.257442b (43982) for ; Wed, 11 Aug 2010 20:49:28 -0400 (EDT) Received: from magic-d23.mail.aol.com (magic-d23.mail.aol.com [172.19.146.157]) by cia-dd04.mx.aol.com (v129.4) with ESMTP id MAILCIADD047-abce4c63451751; Wed, 11 Aug 2010 20:49:27 -0400 From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Wed, 11 Aug 2010 20:49:27 EDT Subject: Re: [LML] Re: flap coupling, LNC2 flap implications X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_e9d5.2f3264c9.39949f17_boundary" X-Mailer: AOL 9.5 sub 155 X-AOL-IP: 24.15.17.119 X-Spam-Flag:NO X-AOL-SENDER: Sky2high@aol.com --part1_e9d5.2f3264c9.39949f17_boundary Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable Chris, =20 Right, So..... =20 I fly at a speed where compressibility has some small effect. The "wing= "=20 performs differently at slow airspeeds. Anyway, the report deals only=20 with section characteristics. We all fly in the true wind tunnel with th= e=20 whole wing - the atmosphere. I agree with the section concepts and=20 measurements. Our wing in flight is what it is. =20 If Wolfgang seeks some engineering numbers, so be it. I say experience= =20 trumps theory or esoteric measurements. =20 Scott =20 =20 In a message dated 8/11/2010 6:23:03 P.M. Central Daylight Time, =20 chris_zavatson@yahoo.com writes: =20 Scott, When the airfoil was tested, M 0.1 was likely used to eliminate =20 compressibility effects. Note that the Reynolds numbers are in the appro= priate range=20 for our application. There is also a chart showing some compressibility= =20 effects. When testing, temperature and/or pressure are changed to vary= =20 Reynolds numbers while maintaining a constant Mach number. The 0.1 Mach= =20 number is not meant to imply usage at 66 kts _http://en.wikipedia.org/wiki/Reynolds_number_=20 (http://en.wikipedia.org/wiki/Reynolds_number)=20 Chris =20 =20 Chris Zavatson N91CZ 360std _www.N91CZ.com_ (http://www.n91cz.com/)=20 =20 ____________________________________ From: "Sky2high@aol.com" To: lml@lancaironline.net Sent: Tue, August 10, 2010 1:52:05 PM Subject: [LML] Re: flap coupling, LNC2 flap implications Chris and Wolfgang, =20 The airfoil report only deals with a section, not the whole wing with its= =20 washout or the whole airplane, etc. Furthermore, while figure 12 indeed= =20 demonstrates drag reduction for a section in reflex, the notation claims= it=20 is at .1 Mach or about 66 Knots. I can't get my head around that since= that=20 is touchdown speed where the flaps should be out of reflex at least. =20 =20 Experience with my airplane tells me that full reflex (perhaps up to -10= =20 degrees in flight out at the twisted flap end) minimizes drag in the speed= =20 range above about 160 KIAS. Below those speeds a nose up attitude (and= AOA)=20 begins to creep in to maintain lift. By the time 120 KIAS is reached my= =20 flaps are in takeoff position (10 degrees down from full reflex). Why?= =20 Because the nose up attitude would be perhaps 6 degrees higher if no flap= s=20 were used. I have never measured the power or speed difference needed to= =20 maintain level flight between the two flap positions (drag indicators for= the=20 same lift) because speeds below 120 are only flown on an approach, in the= =20 pattern or at OSH. =20 =20 I continue to claim that the LNC2 flaps are a fourth control surface that= =20 has important drag implications and significant pitch consequences - =20 certainly more pronounced than that of any spam can. =20 Scott =20 PS - I certainly like the LNC2 continuous flap position capability rather= =20 than fixed detents. Continuous positioning fits its role as another =20 control surface. =20 =20 In a message dated 8/9/2010 6:33:38 P.M. Central Daylight Time, =20 chris_zavatson@yahoo.com writes: =20 =20 Wolfgang, The MkII tail uses a servo to drive the trim tab. If installed, the=20 bob-weight is the only thing contributing to any static force in rear hal= f of=20 the system. If an autopilot is fighting an out of trim condition that wo= uld=20 add some force-much like the old trim system does. Outside of that all= =20 trim forces for the large tail are self-contained in the elevator. Attached are some charts showing the benefits of reflex relative to the = =20 320/360. =20 Chris Zavatson N91CZ 360std _www.N91CZ.com_ (http://www.n91cz.com/)=20 =20 ____________________________________ From: Wolfgang To: lml@lancaironline.net Sent: Mon, August 9, 2010 12:04:51 PM Subject: [LML] Re: flap coupling The push rod forces are definitely there. =20 The trim system that keeps those forces from showing up at the control=20 stick. . . . . unless you're using servo tabs . . . . =20 Yes, I want to map the drag bucket for various flap conditions.=20 NASA tech paper 1865 shows it's effect. I want to expand that on the 300= =20 series. I believe it can add some efficiency points if utilized. =20 Wolfgang =20 ____________________________________ =20 From: Sky2high@aol.com Sender: =20 Subject: Re: [LML] Re: flap coupling Date: Mon, 09 Aug 2010 07:33:19 -04= 00 To:=20 lml@lancaironline.net =20 Uh, the push rod forces should be zero when trimmed. If one cannot reach= =20 a trimmed configuration, then force will be required to reach sustained= =20 level flight. One can only wonder about the position of the trimming dev= ice=20 (there are so many different methods) when one then calculates forces=20 necessary for level flight at different airspeeds/configurations. =20 Wolfgang is seeking the "drag bucket" for different flight regimes. The= =20 purpose is unknown. Each configuration change affects either lift (induc= ed=20 drag) or parasitic drag or both. Faster =3D less induced drag, more=20 parasitic drag. Slower =3D more induced drag, less parasitic. Parasites= are =20 everywhere. =20 _http://www.charlesriverrc.org/articles/asfwpp/lelke_airfoilperf.htm_=20 (http://www.charlesriverrc.org/articles/asfwpp/lelke_airfoilperf.htm) cla= rifies =20 the "drag bucket" concept. Good (an extra "o" converts God to good) Is= =20 only of concern at cruise configurations. Why? Because anything else is= =20 confounded by other variables - density altitude, wind, efficiency, etc.= The=20 designer defined the cruise range as the best conditions (altitude, power= ,=20 etc) where the longeron was level. Other things can affect drag, engine= =20 cooling, laminar flow because of smooth surfaces, weight (lift-induced dr= ag),=20 wax (parasitic drag), etc. etc. etc. =20 =20 Who cares at other speeds less than cruise - we know that max efficiency= =20 can be reached when parasitic drag and induced drag cross at some minima.= =20 Uh, the old max range vs max endurance question. Frequently, best=20 efficiency occurs at best glide speed (like 107 KIAS in a half loaded 320= ). So=20 what? Do I care if I can reach Austin, TX in 8 hours using only 20 gall= ons=20 or 4.3 hours using 30 gallons or 4.8 hours at best power requiring a fuel= =20 stop to maintain minimums (43 gal tank). Of course. But I don't need=20 anything more than ROP/LOP fuel burns and associated TAS - fortunately fo= r my=20 very slick bird, there is only a loss of 6 or 7 knots for a drop of 2 gph= from=20 ROP to LOP at some useful altitude. So, I get >1 hour more endurance at= =20 LOP and I can see if that 28 NM difference (4 hours) is worth the 1 hour= =20 refueling stop. Uh, Austin is a flip of the coin at 820 NM (wind and wea= ther=20 depending). =20 Scott Krueger LNC2 320 =20 =20 =20 In a message dated 8/8/2010 6:46:31 P.M. Central Daylight Time, =20 chris_zavatson@yahoo.com writes: =20 The MKII tail is a little different. Push rod forces are zero for all=20 trimmed conditions. =20 Chris Zavatson =20 N91CZ =20 360std _www.N91CZ.com_ (http://www.n91cz.com/)=20 =20 ____________________________________ From: Wolfgang To: lml@lancaironline.net Sent: Fri, August 6, 2010 10:06:44 PM Subject: [LML] Re: flap coupling I have taken elevator pushrod force measurements and was surprised. Elevator pushrod forces to stick forces are about 6.5 to 1 The trim system, when dialed in, provides these forces. =20 At 190 imph and -7=BA flaps, there is a 60lb forward force. At 80 imph and 10=BA flaps, there is about zero force. At 80 imph and 20=BA flaps, there is a slight (-1lb) rearward force. =20 These numbers are with the horizontal stabilizer built at -1.2=BA - - - plans range is -0.5=BA to -1.0=BA =20 An input from the flap bellcrank of about 20-40 lb at -7=BA would be good= , tapering down to zero lbs at 10=BA flaps =20 A horizontal stabilizer built at -0.5=BA would, of course, change these= =20 numbers. =20 Comments ? =20 Wolfgang =20 -- For archives and unsub =20 http://mail.lancaironline.net:81/lists/lml/List.html --part1_e9d5.2f3264c9.39949f17_boundary Content-Type: text/html; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable <= FONT id=3Drole_document color=3D#000000 size=3D2 face=3DArial>
Chris,
 
Right, So.....
 
I fly at a speed where compressibility has some small effect. &n= bsp;=20 The "wing" performs differently at slow airspeeds.  Anyway, the repor= t=20 deals only with section characteristics.  We all fly in the true= wind=20 tunnel with the whole wing - the atmosphere.  I agree with the= section=20 concepts and measurements.  Our wing in flight is what it is.
 
If Wolfgang seeks some engineering numbers, so be it.  I say=20 experience trumps theory or esoteric measurements.
 
Scott
 
In a message dated 8/11/2010 6:23:03 P.M. Central Daylight Time,=20 chris_zavatson@yahoo.com writes:
http://en.wikipedia.org/wik= i/Reynolds_number
Chris
 
 
Chris Zavatson
N91CZ
360std
From: "Sky2high@aol.com"= =20 <Sky2high@aol.com>
To:=20 lml@lancaironline.net
Sent:=20 Tue, August 10, 2010 1:52:05 PM
Subject: [LML] Re: flap coupling, LNC2=20 flap implications

Chris and Wolfgang,
 
The airfoil report only deals with a section, not the whole wing wi= th its=20 washout or the whole airplane, etc.  Furthermore, while figure= 12=20 indeed demonstrates drag reduction for a section in reflex, the notation= =20 claims it is at .1 Mach or about 66 Knots.  I can't get my hea= d=20 around that since that is touchdown speed where the flaps should be= out=20 of reflex at least. 
 
Experience with my airplane tells me that full reflex (perhaps= up to=20 -10 degrees in flight out at the twisted flap end) minimizes drag in the= speed=20 range above about 160 KIAS.  Below those speeds a nose=20 up attitude (and AOA) begins to creep in to maintain lift.  By= the=20 time 120 KIAS is reached my flaps are in takeoff position (10 degre= es=20 down from full reflex).  Why?  Because the nose up=20 attitude would be perhaps 6 degrees higher if no flaps were used.&n= bsp; I=20 have never measured the power or speed difference needed to maintain lev= el=20 flight between the two flap positions (drag indicators for the same= lift)=20 because speeds below 120 are only flown on an approach, in the pattern= or at=20 OSH. 
 
I continue to claim that the LNC2 flaps are a fourth control surfac= e that=20 has important drag implications and significant pitch consequences= -=20 certainly more pronounced than that of any spam can. =20    
 
Scott
 
PS - I certainly like the LNC2 continuous flap position capability= rather=20 than fixed detents.  Continuous positioning fits its role as= another=20 control surface.
 
In a message dated 8/9/2010 6:33:38 P.M. Central Daylight Time,=20 chris_zavatson@yahoo.com writes:
Wolfgang,
The MkII tail uses a servo to drive the trim tab.  If instal= led,=20 the bob-weight is the only thing contributing to any static force in= rear=20 half of the system.  If an autopilot is fighting an out of trim= =20 condition that would add some force-much like the old trim= system=20 does.  Outside of that all trim forces for the large tail are=20 self-contained in the elevator.
Attached are some charts showing the benefits of reflex relative= to the=20 320/360.
 
Chris Zavatson
N91CZ
360std

From: Wolfgang=20 <Wolfgang@MiCom.net>
To: lml@lancaironline.net
Sent: Mon, August 9, 2010 12:04:51=20 PM
Subject: [LML]= Re: flap=20 coupling

The push rod forces are definitely th= ere.=20
The trim system that keeps those forc= es from=20 showing up at the control stick.
. . . . unless you're using servo tab= s . . .=20 .
 
Yes, I want to map the drag bucket fo= r various=20 flap conditions.
NASA tech paper 1865 shows it's effec= t. I want=20 to expand that on the 300 series.
I believe it can add some efficiency= points if=20 utilized.
 
Wolfgang
<= /TABLE>


--
For=20 archives and unsub=20 http://mail.lancaironline.net:81/lists/lml/List.html

= --part1_e9d5.2f3264c9.39949f17_boundary--
From: Sky2high@aol.com
Sender: <marv= @lancaironline.net>
Subject: Re: [LML] Re: flap coupling<= /TD>
Date: Mon, 09 Aug 2010 07:33:19=20 -0400
To: lml@lancai= ronline.net
Uh, the push rod forces should be zero when trimmed. = If one=20 cannot reach a trimmed configuration, then force will be require= d to=20 reach sustained level flight.  One can only wonder about th= e=20 position of the trimming device (there are so many different met= hods)=20 when one then calculates forces necessary for level flight= at=20 different airspeeds/configurations.
 
Wolfgang is seeking the "drag bucket" for different flight= =20 regimes.  The purpose is unknown.  Each configuration= change=20 affects either lift (induced drag) or parasitic drag or=20 both.  Faster =3D less induced drag, more parasitic drag.&n= bsp;=20 Slower =3D more induced drag, less parasitic.  Parasites ar= e=20 everywhere.
 
http://www.charlesriverr= c.org/articles/asfwpp/lelke_airfoilperf.htm clarifies=20 the "drag bucket" concept.  Good (an extra "o" converts God= to=20 good) Is only of concern at cruise configurations.  Why?&nb= sp;=20 Because anything else is confounded by other variables - density= =20 altitude, wind, efficiency, etc.  The designer defined the= cruise=20 range as the best conditions (altitude, power, etc) where the lo= ngeron=20 was level.  Other things can affect drag, engine cooling,= laminar=20 flow because of smooth surfaces, weight (lift-induced drag), wax= =20 (parasitic drag), etc. etc. etc. 
 
Who cares at other speeds less than cruise - we know= that=20 max efficiency can be reached when parasitic drag and induced dr= ag=20 cross at some minima.  Uh, the old max range vs max enduran= ce=20 question.   Frequently, best efficiency occurs at best glid= e=20 speed (like 107 KIAS in a half loaded 320).  So what?&= nbsp;=20 Do I care if I can reach Austin, TX in 8 hours using only= 20=20 gallons or 4.3 hours using 30 gallons or 4.8 hours at best= power=20 requiring a fuel stop to maintain minimums (43 gal tank). = Of=20 course.  But I don't need anything more than ROP/LOP fuel= burns=20 and associated TAS - fortunately for my very slick bird, th= ere is=20 only a loss of 6 or 7 knots for a drop of 2 gph from ROP to LOP= at=20 some useful altitude.  So, I get >1 hour=20 more endurance at LOP and I can see if that 28 NM diff= erence=20 (4 hours) is worth the 1 hour refueling stop.  Uh, Aus= tin is=20 a flip of the coin at 820 NM (wind and weather depending).
 
Scott Krueger
LNC2 320     
 
In a message dated 8/8/2010 6:46:31 P.M. Central Daylight= Time,=20 chris_zavatson@yahoo.com writes:
The MKII tail is a little different.  Push rod= forces=20 are zero for all trimmed conditions.
 
Chris Zavatson   
N91CZ   
360std

 

From: Wolfgang=20 <Wolfgang@MiCom.net>
To:=20 lml@lancaironline.net
Sent: Fri, August= 6,=20 2010 10:06:44 PM
Subject: [LML] Re: fla= p=20 coupling

I have taken elevator pushrod= force=20 measurements and was surprised.
Elevator pushrod forces to st= ick forces=20 are about 6.5 to 1
The trim system, when dialed= in,=20 provides these forces.
 
At 190 imph and -7=BA fl= aps, there=20 is a 60lb forward force.
At 80 imph and 10=BA flaps,= there is=20 about zero force.
At 80 imph and 20=BA flaps,= there is a=20 slight (-1lb) rearward force.
 
These numbers are with the ho= rizontal=20 stabilizer built at -1.2=BA
- - - plans range is -0.5=BA= to=20 -1.0=BA
 
An input from the flap= bellcrank=20 of about 20-40 lb at -7=BA would be good,
 tapering down to zero= lbs at 10=BA=20 flaps
 
A horizontal stabilizer built= at -0.5=BA=20 would, of course, change these numbers.
 
Comments ?
 
Wolfgang