Today's Message Index:
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1. 10:31 AM - Re: drag curve... (Givan, Max)
2. 11:00 AM - Re: drag curve... (Brian Whittingham)
Message 1
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I am scared and I wasnt even on board for the VNE testing! VNE is
normally set by the manufacturer to tell the aircraft operators the
maximum SAFE indicated airspeed, not the maximum achievable speed in a
dive! Sometimes it is set arbitrarily to reflect the maximum airspeed
that the aircraft was tested at. Thus to exceed it makes you a test
pilot. Often the VNE is set to reflect a speed at which something very
bad will happen. Things like structural failure or unsafe flying
qualities, flutter or mach tuck. Bad things! Now with experimental
aircraft, it is likely that the VNE set by the designer/kit supplier
will be an arbitrary value that they have flown to and not the edge of a
cliff but those 'bad' things are getting closer as you go faster. I for
one am happy you have done these tests as I expect to have a Lightning
in the near future and it provides me with good test data without
risking my own life. Thank you. You are however taking big risks. When
in flight test you find a flutter point, often the aircraft is lost
before its airspeed can be reduced below the flutter point.
Max
________________________________
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of Pete
Sent: Monday, October 09, 2006 8:20 AM
Subject: RE: Lightning-List: drag curve...
I found a similar result when flying N622EA, our second 3300 powered
Esqual back in 2004. It was a very calm day and air was smooth. I
started at 10,000ft and kept pushing the nose over at 2850 rpm.
Indicated speed went up to about 190 mph and did not increase even with
steeper down angles. That aircraft was stock Esqual with wheel pants
all around. It just didn't want to go any faster.
The prototype Lightning goes faster because of a number of things: The
gear leg firings, better wheel pants, much different wing, smoother
cowl, and significant changes to the high drag areas of the fuselage
that were suggested by some former Lancair engineers. I do think we
will see some more improvements in drag reduction from minor changes to
cowl and cooling drag.
Pete
________________________________
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of nick
otterback
Sent: Monday, October 09, 2006 8:38 AM
Subject: Lightning-List: drag curve...
I belive the statement of terminal velocity in this case is used in the
wrong context....it was found during testing with the esqual that a
"Stock" aircraft...all of their items no after market stuff; gearleg,
pressure recovery wheel pants,ect....that the aircrafts total darg would
not allow the airframe accelerate much past 195 IAS at any altitude not
that TAS was higher ...and not taking in to account the static system
errors but the IAS would not accelerate.....now i did do alot of testing
poweron ...below redline RPM and at idle ...the only differance is it
took longer and a steeper angle at idle.......the hybrid would go to
about 210 but not much more .....and the prototype lightning will find
the end of ASI without any problem...245IAS....VNE is not related to the
aircrafts drag curve directly it may be mearly that the nubers are the
same....but not related .....it is just that the airframe can not
accelerate past that AS in its current form......the prototype is clean
enough to fly that fast with out induced drag being much of limiting
facor but the aircraft lacks the power to pull it much past 205 in level
flight .....I am sure this sheds some light but more than likley opens
up another can...
Nick
N1BZRich@aol.com wrote:
In a message dated 10/8/2006 12:42:55 P.M. Eastern Daylight
Time, dashvii@hotmail.com writes:
It was at an altitude of about 12,000 feet starting,
power to idle, nose
down to about 30 degrees and then steeper. I couldn't
get anymore out
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Message 2
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--> Lightning-List message posted by: "Brian Whittingham" <dashvii@hotmail.com>
Max,
The flight testing of VNE is set by flying at least 10% over that
published number. I believe that it was tested to more like 20% over for
extra margin of safety. The prototype is equipped with the ballistic
parachute and Nick wore a personal parachute on top of that. Right now the
Vne is set at 208mph I believe it is on the Lightning. The prototype has
come close to that in 100% throttle in level flight. Production models are
a little slower than the prototype. Brian W.
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