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Date: Sun, 16 Jan 2005 21:15:02 -0500
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Subject: Re: Approved Weights for Lancair IVP/IVPTs
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included in the post below is reference to Dave Morss's LA to Lakeland 6 =
hour record.

I assume he didn't land with empty tanks?  Anyone know how much gas he =
had?
(this is pertinent to the thread).
I don't know what the tailwind was that day but workiing backwards it =
looks like he had to have more than 140 gals
  ----- Original Message -----=20
  From: Brent Regan=20
  Sent: Friday, January 14, 2005 5:14 PM
  Subject: Re: Approved Weights for Lancair IVP/IVPTs


  My thanks to Roberto d'Enginero for providing the calculations that =
substantiate the points that I was trying to make in my previous post, =
those being:

  1)  You can load an aircraft well past its listed gross weight and it =
will still fly.
  2) The more weight you add the less safe the situation.
  3) You cannot fly an airplane with a stall speed greater than its =
maneuvering speed Va.

  Whether the ultimate gross weight is 18,000 or 28,500 pounds is =
irrelevant to the point. In the spirit of Bob's post I should point out =
that Bob is using the wing lift and the gross weight interchangeably. =
This is not correct (I'll take those quarters back). Using the 18,000 =
pound number as the ultimate gross weight is, by design, calculated to =
be conservative. As Bob pointed out, the load carried IN the wings =
(including the wing structure) is not factored . Also not considered is =
the lift generated by the fuselage, the vertical component of the =
propeller thrust at high alpha and the effect of temperature on the =
composite structure.  Bob's assertion that the wings will clap at 18,000 =
pounds gross is very probably inaccurate and would require empirical =
determination. Perhaps Roberto d'Testpilot would volunteer.

  Bob writes " Brent continues with the mythical 200% (8.8G) ultimate =
load factor, which doesn't exist and never has!"

  Ouch, this one is gonna hurt. I would direct you to the Lancair =
published flyer circa 1992 attached.  Next to G Loading (ultimate) you =
will see the "mythical" +8.8. Also note the 2,900 pound gross weight and =
82 gallons of fuel.

  Bob also writes "My apologies to the persons named, it's not the =
purpose of my posting to embarrass anyone."  Not to worry, I am offended =
by people with malicious intent , not by ones who are well meaning but =
misinformed. I suspect the only one you have embarrassed is yourself.

  People who live in false premiss(es) shouldn't throw conclusions.

  My theory is this. The original IV was designed with a 2,900 lb gross =
and a 2.0 to 1 safety factor.  A IV wing weighs about 180 Lbs all up or =
360 Lbs the pair and both will carry 492 Lbs of fuel (original 82 =
gallons) for a total of 852 pounds of wing and fuel and the balance of =
2048 pounds in the fuselage. It is the fuselage that is trying snap off =
the wings so if you reduce the factor of safety to ultimate failure from =
2.0 to 1.5 (Part 23.303 spam can margins) you get a new fuselage weight =
of 2731 lbs. Add back the wing weight and you get  3583 Lbs gross =
weight. Interesting close to the 3550 now published.=20

  The increase in gross weight from 2,900 lbs to 3,550 lbs has come at =
the cost of a reduction in the factor  of safety from ~2.0 to ~1.5. and =
an increase in stall speeds.

  Lancair DID do an empirical wing strength test, back when the earth =
was still cooling, and as I recall (and I am probably wrong) the wing =
failed at ~11 Gs.  This would correspond to a fuselage weight of 22,528 =
and a gross weight of  23,380 lbs. Factor in fuselage lift and vertical =
thrust component and 28,500 isn't so far off the mark. However, a test =
IS the best way to know for sure so, Roberto, if you want your quarter, =
do the test and send me the results. If the wings come off at 23,250 Lbs =
(half way between our numbers) take off weight, you win.=20

  Is a gross weight of 3,550 Lbs safe? Safety is relative and if you =
load your plane more than the situation will allow your relatives will =
find out.

  Regards
  Brent Regan



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<BODY text=3D#000000 bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2>included in the post below is reference =
to Dave=20
Morss's LA to Lakeland 6 hour record.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>I assume he didn't land with empty =
tanks?&nbsp;=20
Anyone know how much gas he had?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>(this is pertinent to the =
thread).</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>I don't know what the tailwind was that =
day but=20
workiing backwards it looks like he had to have more than 140 =
gals</FONT></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
  <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV=20
  style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
  <A title=3Dbrent@regandesigns.com =
href=3D"mailto:brent@regandesigns.com">Brent=20
  Regan</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Friday, January 14, 2005 =
5:14=20
  PM</DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> Re: Approved Weights =
for Lancair=20
  IVP/IVPTs</DIV>
  <DIV><BR></DIV><FONT face=3DArial>My thanks to Roberto d'Enginero for =
providing=20
  the calculations that substantiate the points that I was trying to =
make in my=20
  previous post, those being:<BR><BR>1)&nbsp; You can load an aircraft =
well past=20
  its listed gross weight and it will still fly.<BR>2) The more weight =
you add=20
  the less safe the situation.<BR>3) You cannot fly an airplane with a =
stall=20
  speed greater than its maneuvering speed Va.<BR><BR>Whether the =
ultimate gross=20
  weight is 18,000 or 28,500 pounds is irrelevant to the point. In the =
spirit of=20
  Bob's post I should point out that Bob is using the wing lift and the =
gross=20
  weight interchangeably. This is not correct (I'll take those quarters =
back).=20
  Using the 18,000 pound number as the ultimate gross weight is, by =
design,=20
  calculated to be conservative. As Bob pointed out, the load carried IN =
the=20
  wings (including the wing structure) is not factored . Also not =
considered is=20
  the lift generated by the fuselage, the vertical component of the =
propeller=20
  thrust at high alpha and the effect of temperature on the composite=20
  structure.&nbsp; Bob's assertion that the wings will clap at 18,000 =
pounds=20
  gross is very probably inaccurate and would require empirical =
determination.=20
  Perhaps Roberto d'Testpilot would volunteer.<BR><BR>Bob writes "=20
  </FONT><BIG><FONT face=3Darial size=3D2><BIG>Brent continues with the =
mythical=20
  200% (8.8G) ultimate load factor, which doesn't exist and never=20
  has!"<BR><BR>Ouch, this one is gonna hurt. I would direct you to the =
Lancair=20
  published flyer circa 1992 attached.&nbsp; Next to G Loading =
(ultimate) you=20
  will see the "mythical" +8.8. Also note the 2,900 pound gross weight =
and 82=20
  gallons of fuel.<BR><BR>Bob also writes "</BIG></FONT></BIG><FONT =
face=3Darial=20
  size=3D2><BIG>My apologies to the persons named, it's not the purpose =
of my=20
  posting to embarrass anyone."&nbsp; Not to worry, I am offended by =
people with=20
  malicious intent , not by ones who are well meaning but misinformed. I =
suspect=20
  the only one you have embarrassed is yourself.<BR><BR>People who live =
in false=20
  premiss(es) shouldn't throw conclusions.<BR><BR>My <B>theory</B> is =
this. The=20
  original IV was designed with a 2,900 lb gross and a 2.0 to 1 safety=20
  factor.&nbsp; A IV wing weighs about 180 Lbs all up or 360 Lbs the =
pair and=20
  both will carry 492 Lbs of fuel (original 82 gallons) for a total of =
852=20
  pounds of wing and fuel and the balance of 2048 pounds in the =
fuselage. It is=20
  the fuselage that is trying snap off the wings so if you reduce the =
factor of=20
  safety to ultimate failure from 2.0 to 1.5 (Part 23.303 spam can =
margins) you=20
  get a new fuselage weight of 2731 lbs. Add back the wing weight and =
you=20
  get&nbsp; 3583 Lbs gross weight. Interesting close to the 3550 now =
published.=20
  <BR><BR>The increase in gross weight from 2,900 lbs to 3,550 lbs has =
come at=20
  the cost of a reduction in the factor&nbsp; of safety from ~2.0 to =
~1.5. and=20
  an increase in stall speeds.<BR><BR>Lancair DID do an empirical wing =
strength=20
  test, back when the earth was still cooling, and as I recall (and I am =

  probably wrong) the wing failed at ~11 Gs.&nbsp; This would correspond =
to a=20
  fuselage weight of 22,528 and a gross weight of&nbsp; 23,380 lbs. =
Factor in=20
  fuselage lift and vertical thrust component and 28,500 isn't so far =
off the=20
  mark. However, a test IS the best way to know for sure so, Roberto, if =
you=20
  want your quarter, do the test and send me the results. If the wings =
come off=20
  at 23,250 Lbs (half way between our numbers) take off weight, you win. =

  <BR><BR>Is a gross weight of 3,550 Lbs safe? Safety is relative and if =
you=20
  load your plane more than the situation will allow your relatives will =
find=20
  out.<BR><BR>Regards<BR>Brent Regan<BR></BIG></FONT>
  <P>
  <HR>

  <P></P>
  <P>
  <CENTER><IMG=20
  src=3D"CID:{94E0C59B-48B8-499B-B566-33A470C2EBAE}/Lancair =
Flyer.jpg"></CENTER></BLOCKQUOTE></BODY></HTML>

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