X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 10 Aug 2010 16:52:05 -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 4425039 for lml@lancaironline.net; Tue, 10 Aug 2010 09:19:19 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.206.40; envelope-from=Sky2high@aol.com Received: from imo-ma01.mx.aol.com (imo-ma01.mx.aol.com [64.12.78.136]) by imr-ma02.mx.aol.com (8.14.1/8.14.1) with ESMTP id o7ADISCA032257 for ; Tue, 10 Aug 2010 09:18:28 -0400 Received: from Sky2high@aol.com by imo-ma01.mx.aol.com (mail_out_v42.9.) id q.dbe.f7dc176 (37659) for ; Tue, 10 Aug 2010 09:18:21 -0400 (EDT) Received: from magic-m26.mail.aol.com (magic-m26.mail.aol.com [172.20.22.199]) by cia-mb07.mx.aol.com (v129.4) with ESMTP id MAILCIAMB071-931b4c61519c82; Tue, 10 Aug 2010 09:18:21 -0400 From: Sky2high@aol.com X-Original-Message-ID: <56a9d.5b2c0356.3992ab9c@aol.com> X-Original-Date: Tue, 10 Aug 2010 09:18:20 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_56a9d.5b2c0356.3992ab9c_boundary" X-Mailer: AOL 9.5 sub 155 X-AOL-ORIG-IP: 24.15.17.119 X-AOL-IP: 172.20.22.199 X-Spam-Flag:NO X-AOL-SENDER: Sky2high@aol.com --part1_56a9d.5b2c0356.3992ab9c_boundary Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable 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 half= 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 efficie= ncy=20 occurs at best glide speed (like 107 KIAS in a half loaded 320). So what= ?=20 Do I care if I can reach Austin, TX in 8 hours using only 20 gallons or= =20 4.3 hours using 30 gallons or 4.8 hours at best power requiring a fuel st= op =20 to maintain minimums (43 gal tank). Of course. But I don't need anythin= g=20 more than ROP/LOP fuel burns and associated TAS - fortunately for my very= =20 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_56a9d.5b2c0356.3992ab9c_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 and Wolfgang,
 
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=20 indeed demonstrates drag reduction for a section in reflex, the notation= claims=20 it is at .1 Mach or about 66 Knots.  I can't get my head around= that=20 since that is touchdown speed where the flaps should be out of reflex= at=20 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 degrees= down=20 from full reflex).  Why?  Because the nose up attitude woul= d be=20 perhaps 6 degrees higher if no flaps were used.  I have never measure= d the=20 power or speed difference needed to maintain level flight between the= two=20 flap positions (drag indicators for the same lift) because speeds below 12= 0 are=20 only flown on an approach, in the pattern or at OSH. 
 
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
 
PS - I certainly like the LNC2 continuous flap position capability ra= ther=20 than fixed detents.  Continuous positioning fits its role as ano= ther=20 control surface.
 
In a message dated 8/9/2010 6:33:38 P.M. Central Daylight Time,=20 chris_zavatson@yahoo.com writes:
www.N91CZ.com
From: Wolfgang=20 <Wolfgang@MiCom.net>
T= o: 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 ther= e.=20
The trim system that keeps those forces= from=20 showing up at the control stick.
. . . . unless you're using servo tabs= . . .=20 .
 
Yes, I want to map the drag bucket for= various=20 flap conditions.
NASA tech paper 1865 shows it's effect.= I want to=20 expand that on the 300 series.
I believe it can add some efficiency po= ints if=20 utilized.
 
Wolfgang



--
For=20 archives and unsub=20 http://mail.lancaironline.net:81/lists/lml/List.html
--part1_56a9d.5b2c0356.3992ab9c_boundary--
From: Sky2high@aol.com
Sender: <marv@lancaironline.net>=
Subject: Re: [LML] Re: flap coupling
Date: Mon, 09 Aug 2010 07:33:19=20 -0400
To: lml@lancaironl= ine.net
Uh, the push rod forces should be zero when trimmed.  If= one=20 cannot reach a trimmed configuration, then force will be required= to=20 reach sustained level flight.  One can only wonder about the= =20 position of the trimming device (there are so many different metho= ds)=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 ch= ange=20 affects either lift (induced drag) or parasitic drag or both.=  =20 Faster =3D less induced drag, more parasitic drag.  Slower = =3D more=20 induced drag, less parasitic.  Parasites are everywhere.
 
http://www.charlesriverrc.org/art= icles/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? = ;=20 Because anything else is confounded by other variables - density= =20 altitude, wind, efficiency, etc.  The designer defined the cr= uise=20 range as the best conditions (altitude, power, etc) where the long= eron=20 was level.  Other things can affect drag, engine cooling, lam= inar=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 tha= t max=20 efficiency can be reached when parasitic drag and induced drag cro= ss at=20 some minima.  Uh, the old max range vs max endurance question= .=20   Frequently, best efficiency occurs at best glide speed (lik= e 107=20 KIAS in a half loaded 320).  So what?  Do I care if= I can=20 reach Austin, TX in 8 hours using only 20 gallons or 4.3 hour= s=20 using 30 gallons or 4.8 hours at best power requiring a fuel= stop=20 to maintain minimums (43 gal tank).  Of course.  But I= don't=20 need anything more than ROP/LOP fuel burns and associated TAS -=20 fortunately for my very slick bird, there is only a loss of= 6 or 7=20 knots for a drop of 2 gph from ROP to LOP at some useful=20 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=20 hour refueling stop.  Uh, Austin is a flip of the coin at 820= NM=20 (wind and weather depending).
 
Scott Krueger
LNC2 320     
 
In a message dated 8/8/2010 6:46:31 P.M. Central Daylight Tim= e,=20 chris_zavatson@yahoo.com writes:
The MKII tail is a little different.  Push rod fo= rces=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, 2010=20 10:06:44 PM
Subject: [LML] Re: flap=20 coupling

I have taken elevator pushrod= force=20 measurements and was surprised.
Elevator pushrod forces to stic= k forces=20 are about 6.5 to 1
The trim system, when dialed in= , provides=20 these forces.
 
At 190 imph and -7=BA flap= s, there is=20 a 60lb forward force.
At 80 imph and 10=BA flaps, the= re is about=20 zero force.
At 80 imph and 20=BA flaps, the= re is a=20 slight (-1lb) rearward force.
 
These numbers are with the hori= zontal=20 stabilizer built at -1.2=BA
- - - plans range is -0.5=BA to= =20 -1.0=BA
 
An input from the flap bel= lcrank of=20 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
 
=