I concur with Skip's assessment. Vne is a limit just like G-- if you exceed the limits recommended by Lancair you are a test pilot and the risk goes up dramatically. LOBO does not endorse exceeding these limits. Our members are currently paying the price of limited insurance coverage because of those Lancair pilots who have exceeded their abilites and the limits of their aircraft. One IVP was lost in August 2005 after spending a week next to me at Oshkosh (see below for those of you who incorrectly believe that there are no Lancair accidents involving this stuff) and the airframe failed above Vne near the predicted Vne value. Lynn Farnsworth has gone to great lengths to study the issue, strengthen the airframe and reduce his risk. Most of the rest of us have not. I applaud Lynn for his efforts and the methodolgy he has employed. If you want to expand the envelope of your aircraft then it will take some dedicated engineering and redesign-- not simply stating "well Lance over designed it to begin with" wishful thinking. There are many real smart people like Robert Wolf (who has a PhD in aero and over 30 years experience in the industry) who have given you the benefit of their decades of experience --please listen to them and enjoy your Lancairs safely this holiday season and in the future.
Best Regards,
Jeff Edwards
President, LOBO
Excerpts from the Canadian report for Sterling Ainsworth's accident is as follows.
"The Lancair IV design was subjected to computer analysis and static load testing, and a full flutter test program was conducted. These tests showed that the tail section would fail first due to flutter at Mach 0.57 followed by failure of the wing flap assemblies at Mach 0.6. During the descent the aircraft reached a calculated speed of 412 knots or Mach 0.62."
The aircraft fuselage and left wing spar were located approximately eight nautical miles (nm) southeast of Sundre, Alberta. The right wing, left wing skins, and pieces of the tail section were located over a 1.3 nm debris field in a line southwest of the main wreckage site. The pilot and passenger were fatally injured.
1918:34 - aircraft descended through 17 330 feet at 12 500 feet per minute; pitch attitude 36º nose down; bank angle 66º right; speed 88 KIAS; climb power was still set
1918:48 - aircraft descended through 10 840 feet; speed KIAS 150 (Based on altitude change, time, and ground speed, calculations show that the aircraft reached a peak velocity of 412 knots [Mach 0.62] going through 11 000 feet)
1919:12 - last data point recorded at 3870 feet; elevation of accident site 3640 feet
- At the time of the accident, the aircraft was 250 to 350 pounds over the recommended gross take-off weight, which increased the stall speed by approximately 17 knots.
-----Original Message-----
From: Skip Slater <skipslater@verizon.net>
To: lml
Sent: Thu, Dec 3, 2009 5:21 am
Subject: [LML] Re: Vne is NOT a meaningless number
"One IVP was lost years ago when it exceeded Vne."
Gene Long's ES also broke up in flight when it exceeded VNE during it's inexplicable descent from cruse altitude a year an a half ago.
The fact it this: No amount of pilot skill will save a plane once flutter begins to break it apart. If you knowingly exceed VNE, you are a test pilot and the only way you'll know you went too fast is as your plane is going down in pieces. Pilots who willfully ignore manufacturer established limitations are accidents looking for a place to happen. Pilots who brag about such exploits deserve a very wide berth.
I have to wonder what the instructors from HIPAT and LOBO would have to say on this subject. If they're listening, I hope they'll chime in.
Skip Slater