Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Tue, 28 Sep 2004 15:10:08 -0400 Message-ID: X-Original-Return-Path: Received: from mail-relay-2.tiscali.it ([213.205.33.42] verified) by logan.com (CommuniGate Pro SMTP 4.2.3) with ESMTP id 435502 for lml@lancaironline.net; Tue, 28 Sep 2004 13:25:45 -0400 Received-SPF: none receiver=logan.com; client-ip=213.205.33.42; envelope-from=robert.overmars@tiscali.it Received: from trottolino (62.11.1.174) by mail-relay-2.tiscali.it (7.1.021.3) id 415293410017E7C6; Tue, 28 Sep 2004 19:25:14 +0200 X-Original-Message-ID: <005f01c4a580$e85b21e0$ae010b3e@interbusiness.it> From: "Robert Overmars" X-Original-To: "Lancair Mailing List" X-Original-Cc: Subject: wing incidence indifference X-Original-Date: Tue, 28 Sep 2004 19:30:51 +0200 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_005C_01C4A591.AA0DF960" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 This is a multi-part message in MIME format. ------=_NextPart_000_005C_01C4A591.AA0DF960 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable salutti tutti, Mike and others... Early this year I closed a set of LIV wings which are now installed on = the fuselage. The wing is perfectly straight, ie at x% chord at BL 25.5 = the wing surface is a perfectly straight line to the corresponding x% = chord at the tip, which is the design intention. Imagine a 4 metre = straight edge placed on the wing surface, at any % of chord at BL25.5, = top or bottom surface of the wing, the wing surface is perfectly = straight to the same % chord at the tip. Of course the leading edges and = trailing edges are, from root to tip also perfectly straight lines. When mounted to the fuselage the wing incidence is 1.6 degress nose up = + - 0.05 degrees at BL25.5, it is 0.3 degrees nose low + - 0.1 degrees = or better at BL 171. My wing has 1.9 degrees of washout between BL25.5 = and BL 171 with less than 0.1 degrees of difference anywhere along the = span. Considering that in the design the washout is 2.0 degrees between = the root at BL 0 and BL 171, 1.9 degrees of washout between BL25.5 and = BL 171 is about right. This wing jig was built with bits of ply and crude simple hand tools. = (Was it Bob P's comment "bit's of 1/2" ply cut with a jig saw"?....to = this I say metaphorically; your block of flawed marble, might be, to = Giambologna "The Rape of the Sabine Women" 1583) The wing kit was one = of those old fashioned "slow" build wings which had been partly built = but poorly so we made the decision to strip and rebuild. I developed the = BL 25.5 and BL171 profiles from data and found some variation from the = blueprints. I carefully calculated flap track angles and position and = set the flap tracks accordingly. We'd purchased new flap tracks and flap = roller plates from Lancair and upon receipt of the flap tracks I noticed = the flap tracks to be slightly different from our originals so I = installed the rollers onto the roller plates then to the flap tracks and = lo and behold the plates were unable to travel the full travel of the = flap track slots locking up a little past about 30 degrees of travel. = (Shame on you Lancair that no-one notices such simple things) After = machining the track slots just a little I had the full 40 degrees of = travel so went ahead and used them. After building the flaps and = connecting the port and stbd flap bellcranks with an interconnecting = pushrod I measured 7.5 pounds on the pushrod to pull both flaps up to = the fully extended position. Incidentally in the retracted position each = of the flap track rollers is snug to it's forward position in it's = respective slot plus or minus a poofteenth of nothing, as is the case in = the fully extended position. In my opinion if Lancair's Building "Assist" Program is not giving you = results like this then it's a waste of time and money. To be building = wings with 1.7 degrees of incidence (in)difference is truely and = extraordinarily bad considering that the Company is supposed to be the = expert on Lancair building. No matter where it's been done Phillipines, = Redmond, Timbuktu, a wing built out of spec pulled into an accurate jig = and then closed up, when closed and released from the jig will spring = back to some extent, I know this from experience from "fast build" = wings. Perfectly straight and accurate jigs will produce perfectly = straight wings PERIOD. If I in my efforts produced such poor and = dangerous wings I'd be truely ashamed and give up building these = aeroplanes I love so much. I also believe that using eccentric bushes to change wing incidence is = not just poor practice but quite potentially dangerous. Perhaps Lancair = Company might give the details of who in the Company has analysed this = procedure, their qualifications and the analysis results including but = not limited to the load carrying capability of the twisted spar at it's = maximum load, the stall response of the asymmetric wing and stall = progression from root to tip as is the design intent, the stall response = under gust loads upto the structural limit of the aeroplane (the top of = the green arc of the ASI) and beyond, the stall response with flaps = partially and fully extended, the consequent differences in flap rigging = and aileron rigging etc. I await Lancair's response.... ciao, Roberto d'Italia.=20 ------=_NextPart_000_005C_01C4A591.AA0DF960 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
salutti tutti,
 
Mike and others...
 
Early this year I closed a set of LIV = wings which=20 are now installed on the fuselage. The wing is perfectly straight, = ie=20 at x% chord at BL 25.5 the wing surface is a perfectly = straight line=20 to the corresponding x% chord at the tip, which is the design=20 intention. Imagine a 4 metre straight edge placed on the wing = surface, at=20 any % of chord at BL25.5, top or bottom surface of the wing,  the = wing=20 surface is perfectly straight to the same % chord at the tip. Of course = the=20 leading edges and trailing edges are, from root to tip also perfectly = straight=20 lines.
 
When mounted to the fuselage the = wing=20 incidence is 1.6 degress nose up  + - 0.05 degrees at BL25.5,  = it is=20 0.3 degrees nose low + - 0.1 degrees or better at BL = 171.  My=20 wing has 1.9 degrees of washout between BL25.5 and BL 171 with less = than=20 0.1 degrees of difference anywhere along the span. Considering that in = the=20 design the washout is 2.0 degrees between the root at BL 0 and BL 171, = 1.9=20 degrees of washout between BL25.5 and BL 171 is about = right.
 
This wing jig was built with bits of = ply and crude=20 simple hand tools. (Was it Bob P's comment "bit's of 1/2" ply cut with a = jig=20 saw"?....to this I say metaphorically; your block of flawed marble, = might=20 be, to Giambologna "The Rape of the Sabine Women" 1583)   The = wing=20 kit was one of those old fashioned "slow" build wings which = had been=20 partly built but poorly so we made the decision to strip and rebuild. I=20 developed the BL 25.5 and BL171 profiles from data and found = some=20 variation from the blueprints. I carefully calculated flap track = angles and=20 position and set the flap tracks accordingly. We'd purchased = new flap=20 tracks and flap roller plates from Lancair and upon receipt of the flap = tracks I=20 noticed the flap tracks to be slightly different from our originals = so I=20 installed the rollers onto the roller plates then to the flap = tracks and lo=20 and behold the plates were unable to travel the full travel of the = flap=20 track slots locking up a little past about 30 degrees of travel. (Shame = on you=20 Lancair that no-one notices such simple things) After machining the = track slots=20 just a little I had the full 40 degrees of travel so went ahead and = used=20 them. After building the flaps and connecting the port and stbd flap = bellcranks=20 with an interconnecting pushrod I measured 7.5 pounds on the = pushrod to=20 pull both flaps up to the fully extended position. Incidentally in = the=20 retracted position each of the flap track rollers is snug to it's = forward=20 position in it's respective slot plus or minus a poofteenth of = nothing, as=20 is the case in the fully extended position.
 
In my opinion if Lancair's Building = "Assist"=20 Program is not giving you results like this then it's a waste of time = and money.=20 To be building wings with 1.7 degrees of incidence (in)difference = is truely=20 and extraordinarily bad considering that the Company is supposed to be = the=20 expert on Lancair building.  No matter where it's been done = Phillipines,=20 Redmond, Timbuktu, a wing built out of spec pulled into an = accurate jig and=20 then closed up, when closed and released from the jig will spring = back to=20 some extent, I know this from experience from "fast build" wings. = Perfectly=20 straight and accurate jigs will produce perfectly straight wings=20 PERIOD.   If I in my efforts produced such poor and = dangerous=20 wings I'd be truely ashamed and give up building these aeroplanes I love = so=20 much.
 
I also believe that using eccentric = bushes to=20 change wing incidence is not just poor practice but quite potentially = dangerous.=20 Perhaps Lancair Company might give the details of who in the Company has = analysed this procedure, their qualifications and the analysis results = including=20 but not limited to the load carrying capability of the twisted spar at = it's=20 maximum load, the stall response of the asymmetric wing and stall = progression=20 from root to tip as is the design intent, the stall response under gust = loads=20 upto the structural limit of the aeroplane (the top of the green arc of = the ASI)=20 and beyond, the stall response with flaps partially and fully = extended, the=20 consequent differences in flap rigging and aileron rigging=20 etc.
 
I await Lancair's = response....
 
ciao,
 
Roberto d'Italia. 
 
 
 
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