X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 27 Jan 2009 18:46:36 -0500 Message-ID: X-Original-Return-Path: Received: from web62501.mail.re1.yahoo.com ([69.147.75.93] verified) by logan.com (CommuniGate Pro SMTP 5.2.12) with SMTP id 3453319 for lml@lancaironline.net; Mon, 26 Jan 2009 13:28:56 -0500 Received: (qmail 19526 invoked by uid 60001); 26 Jan 2009 18:28:55 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type:Message-ID; b=boGAI0JMPJJD0TRI5aT5KchuD24Xw3dVR03IrnCrO30/8iv+sE/OAV+im2LQteDqyKHa556Kizokh8Aji+7eBRpVhqIqWBRauNSj/lz+/x4f2g7NZD29MvhgyMPQGHL1jMKbL4ohifF+ieIPwhsBiY7KKGnafoeWr0xmw8vxxrg=; X-YMail-OSG: lUzStmcVM1k3rP9ms4X7TIkzhxsUrjoDLzv6vcsmcISqeB_O9aPQrb8ey9cF..kjOGVdLaWyuEXUTpnLKnztqJm6UhGxLLK1GCAjt4UXNNhtBaWdTJFC1nHt7Ed.V9FOUBYGzsBp2wEmkq8vphgdjQp2mS2t3yulmcg2UwzIrGAyAB7QizXOi6MtyYytfmPxlCsFAKf1I2tyj.8lj89UUXdZRHUd Received: from [97.104.165.236] by web62501.mail.re1.yahoo.com via HTTP; Mon, 26 Jan 2009 10:28:55 PST X-Mailer: YahooMailWebService/0.7.260.1 X-Original-Date: Mon, 26 Jan 2009 10:28:55 -0800 (PST) From: Charlie Kohler Subject: Re: [LML] Re: air intake X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1685151099-1232994535=:19374" X-Original-Message-ID: <483917.19374.qm@web62501.mail.re1.yahoo.com> --0-1685151099-1232994535=:19374 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable For your consideration, =A0 I have had the privilege of meeting and getting to know Martin Hollman. For= those that may not know him and his=A0role in the development of the IV, a= n excerpt from his webpage gives a general description of his involvement i= n the design, stress and flutter analysis of the Lancair-IV. =A0 From his webpage=A0http://www.aircraftdesigns.com/lancair.html =A0 "In 1988, Lance contacted Martin to help design a four place aircraft aroun= d a Continental TSIO-550A engine which had 350 hp at 2,700 rpm. From the ou= tset the aircraft was designed to be pressurized and fly at 24,000 ft. I ca= lled my good friend and aerodynamicist, Rick McWilliams to design the wing = and I designed the structure and stressed everything. The Lancair IV was bu= ilt in 1.5 years and introduced at Oshkosh in 1990. The first prototype and= kits were not pressurized. On a Friday in July, 1990, Lance and Dave Morss= took off for Oshkosh, flying at 19,000 feet and using oxygen, the cruise s= peed was 300 kts. About 25 Lancair IVs were sold that year at Oshkosh. The = Lancair IV was fast and Dave Morss went on to set many records with it such= as flying from Los Angeles, CA to Florida in 6 hours and 2 minutes at 24,0= 00 ft. averaging 385 mph. Below, left Don Goetz is clowning around during t= he lead shot load test of the LIV wing test. Lance with his back to the picture is not amused. " =A0 =A0 In my meetings with Martin we discussed several issues that have come up ov= er the years in the building and flying of the Lancair-IV. =A0 The one issue that we're dealing with in this thread is the cutting of hole= s in the aft fuselage.=20 =A0 He thought it was inadvisable due to harmonics and flutter. No testing, com= puter or otherwise have been completed that would give you assurance that y= ou can handle turbulence-- to whatever degree-- that you encounter. I sugge= sted that if we were to reinforce skin around the hole--=A0 would we be abl= e to regain the strength??-- his answer was no. =A0 Airframe breakup=A0analysis of the IV's=A0that have encountered thunder= storms has been unavailable.=20 We could debate forever the forces of thunderstorms and the inability of ou= r aircraft to sustain such loads, but I do remember that post-World War II = testing put fighter aircraft into thunderstorms and nearly all were able to= fly out. Our cap strip method, carbon fiber materials, hardware backup for= critical bonds, overdesigned bid schedules (Martin said that all schedules= were to designed strength plus 30%!!). I have flown the Mountain West in m= y IV many times. And I am very grateful for these margins of safety.=20 =A0 It would be an extremely interesting study to determine how many aircraft t= hat have had in-flight structural failures correlated to their fuselage mod= ifications. Sad to say, but if you have a failure in this area, there will = not be many pieces left. Just another insurance claim. =A0 Point of interest--- where do you think=A0the "weak link" is in the Lancair= IV?? What would you inspect after a hard landing or severe turbulence encounter? Write me off line and I'll give you the answers. Charlie K. See=A0me on the Web at=A0 www.Lancair-IV.com --- On Mon, 1/26/09, Robert Pastusek wrote: From: Robert Pastusek Subject: [LML] Re: air intake To: lml@lancaironline.net Date: Monday, January 26, 2009, 7:42 AM UNKNOWN { =09FONT-FAMILY: Calibri; panose-1: 2 15 5 2 2 2 4 3 2 4 } #yiv167652127 #yiv167652127 P.MsoNormal { =09FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman", "s= erif" } #yiv167652127 LI.MsoNormal { =09FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman", "s= erif" } #yiv167652127 DIV.MsoNormal { =09FONT-SIZE: 12pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Times New Roman", "s= erif" } #yiv167652127 A:link { =09COLOR: blue; TEXT-DECORATION: underline } #yiv167652127 SPAN.MsoHyperlink { =09COLOR: blue; TEXT-DECORATION: underline } #yiv167652127 A:visited { =09COLOR: purple; TEXT-DECORATION: underline } #yiv167652127 SPAN.MsoHyperlinkFollowed { =09COLOR: purple; TEXT-DECORATION: underline } #yiv167652127 SPAN.EmailStyle17 { =09COLOR: windowtext; FONT-FAMILY: "Arial", "sans-serif" } #yiv167652127 SPAN.EmailStyle18 { =09COLOR: #1f497d; FONT-FAMILY: "Calibri", "sans-serif" } #yiv167652127 .MsoChpDefault { =09FONT-SIZE: 10pt } UNKNOWN { =09MARGIN: 1in 1.25in } #yiv167652127 DIV.Section1 { =09 } Ralf B wrote:=20 =A0 I assume that the air intake in the tail is originally designed to be used = for the ac unit and that the previous owner cut a hole in the bottom of the= fuselage to force more air through the heat exchanger of ac unit. I want t= o close the hole in my tail now since I am not using this air intake. =A0 Would you recommend my plan or does the air intake in the tail serve anothe= r purpose?=20 =A0 =A0 Ralf, The =93original=94 Lancair IV did not have air conditioning, and was not pr= essurized. The air intake in the tail was used to collect high pressure air= in this area and duct it forward for cabin ventilation/cooling. It worked = extremely well. When later models of the IV were pressurized, a flapper val= ve was added where this ventilation air passed into the cockpit at the rear= pressure bulkhead so ventilation air could move forward into the cockpit, = but cockpit pressurization air could not =93leak=94 backward through the ve= ntilation ducting. This system also works well, but you can either have a = =93ventilated=94 or a pressurized cockpit; but not both at the same time. A= s a result, some builders, especially those who installed air conditioners,= just eliminated the cockpit ventilation feature completely and used the A/= C for cooling. From your description, that=92s the configuration you have= =85the air intake in the tail has not been connected to the cockpit through ducting=97typically along the fuselage top. =A0 Before closing off the tail inlet, I=92d check carefully on the air flow th= rough the A/C heat exchanger. It=92s possible the heat exchanger uses air f= rom both sources, although either should be adequate in most conditions. Yo= u didn=92t say where the air exited the fuselage after it passed across the= heat exchanger=85this is a consideration as well, as the total A/C effecti= veness/efficiency depends on the condenser working properly. If you=92re sa= tisfied with the outflow, I=92d suggest plugging the tail opening with Styr= ofoam to test the effect, and if the A/C and aircraft ventilation systems s= till work to your satisfaction, glass over the plug and paint=85 =A0 Hope this helps; glad to exchange information with you off-line if desired. =A0 Bob Pastusek --0-1685151099-1232994535=:19374 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable
For your consideration,
 
I have had the privilege of meeting and getting to know Martin Hollman= . For those that may not know him and his role in the development of t= he IV, an excerpt from his webpage gives a general description of his invol= vement in the design, stress and flutter analysis of the Lancair-IV.
 
 
"In 1988, Lance c= ontacted Martin to help design a four place aircraft around a Continental T= SIO-550A engine which had 350 hp at 2,700 rpm. From the outset the aircraft= was designed to be pressurized and fly at 24,000 ft. I called my good frie= nd and aerodynamicist, Rick McWilliams to design the wing and I designed th= e structure and stressed everything. The Lancair IV was built in 1.5 years = and introduced at Oshkosh in 1990. The first prototype and kits were not pr= essurized. On a Friday in July, 1990, Lance and Dave Morss took off for Osh= kosh, flying at 19,000 feet and using oxygen, the cruise speed was 300 kts. About 25 Lancair IVs were sold that year at Oshkosh. The Lanc= air IV was fast and Dave Morss went on to set many records with it such as = flying from Los Angeles, CA to Florida in 6 hours and 2 minutes at 24,000 f= t. averaging 385 mph. Below, left Don Goetz is clowning around during the lead shot load test of the LIV wing test. Lance with his back to the p= icture is not amused. "
 
 
In my meetings with Martin we discussed several issues that have come = up over the years in the building and flying of the Lancair-IV.
 
The one issue that we're dealing with in this thread is the cutting of= holes in the aft fuselage.
 
He thought it was inadvisable due to harmonics and flutter. No testing= , computer or otherwise have been completed that would give you assurance t= hat you can handle turbulence-- to whatever degree-- that you encounter. I = suggested that if we were to reinforce skin around the hole--  would w= e be able to regain the strength??-- his answer was no.
  Airframe breakup analysis of the IV's that have encou= ntered thunderstorms has been unavailable.
We could debate forever the forces of thunderstorms and the inability = of our aircraft to sustain such loads, but I do remember that post-World Wa= r II testing put fighter aircraft into thunderstorms and nearly all were ab= le to fly out. Our cap strip method, carbon fiber materials, hardware backu= p for critical bonds, overdesigned bid schedules (Martin said that all sche= dules were to designed strength plus 30%!!). I have flown the Mountain West= in my IV many times. And I am very grateful for these margins of safety. <= /DIV>
 
It would be an extremely interesting study to determine how many aircr= aft that have had in-flight structural failures correlated to their fuselag= e modifications. Sad to say, but if you have a failure in this area, there = will not be many pieces left. Just another insurance claim.
 
Point of interest--- where do you think the "weak link" is in the= Lancair IV??
What would you inspect after a hard landing or severe turbulence encou= nter?
Write me off line and I'll give you the answers.
Charlie K.
See me on the Web at  www.Lancair-IV.com


--- On Mon, 1/26/09, Robert Pastusek <rpastusek@htii.com> wrote:
From: Robert Pastusek <rpastusek@htii.com>
S= ubject: [LML] Re: air intake
To: lml@lancaironline.net
Date: Monday, = January 26, 2009, 7:42 AM

Ralf B wrote:

 

I assume that the air intake in the tail is originally design= ed to be used for the ac unit and that the previous owner cut a hole in the= bottom of the fuselage to force more air through the heat exchanger of ac = unit. I want to close the hole in my tail now since I am not using this air= intake.

 

Would you recommend my plan or does the air intake in the tai= l serve another purpose?

 

 

Ralf,

The =93original=94 Lancair IV did not have = air conditioning, and was not pressurized. The air intake in the tail was u= sed to collect high pressure air in this area and duct it forward for cabin= ventilation/cooling. It worked extremely well. When later models of the IV= were pressurized, a flapper valve was added where this ventilation air pas= sed into the cockpit at the rear pressure bulkhead so ventilation air could= move forward into the cockpit, but cockpit pressurization air could not = =93leak=94 backward through the ventilation ducting. This system also works= well, but you can either have a =93ventilated=94 or a pressurized cockpit;= but not both at the same time. As a result, some builders, especially thos= e who installed air conditioners, just eliminated the cockpit ventilation f= eature completely and used the A/C for cooling. From your description, that=92s the configuration you have=85the air intake in the tail has not b= een connected to the cockpit through ducting=97typically along the fuselage= top.

 

Before closing off the tail inlet, I=92d ch= eck carefully on the air flow through the A/C heat exchanger. It=92s possib= le the heat exchanger uses air from both sources, although either should be= adequate in most conditions. You didn=92t say where the air exited the fus= elage after it passed across the heat exchanger=85this is a consideration a= s well, as the total A/C effectiveness/efficiency depends on the condenser = working properly. If you=92re satisfied with the outflow, I=92d suggest plu= gging the tail opening with Styrofoam to test the effect, and if the A/C an= d aircraft ventilation systems still work to your satisfaction, glass over = the plug and paint=85

 

Hope this helps; glad to exchange informati= on with you off-line if desired.

 

Bob Pastusek

--0-1685151099-1232994535=:19374--