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max.givan(at)ngc.com
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 Posted: Mon Oct 23, 2006 9:31 am Post subject: drag curve... |
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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(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of Pete
Sent: Monday, October 09, 2006 8:20 AM
To: lightning-list(at)matronics.com
Subject: RE: 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(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of nick otterback
Sent: Monday, October 09, 2006 8:38 AM
To: lightning-list(at)matronics.com
Subject: 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(at)aol.com wrote:
| Quote: |
In a message dated 10/8/2006 12:42:55 P.M. Eastern Daylight Time, dashvii(at)hotmail.com writes:
| Quote: |
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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dashvii(at)hotmail.com
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| Posted: Mon Oct 23, 2006 10:00 am Post subject: drag curve... |
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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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vettin74(at)yahoo.com
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| Posted: Wed Oct 25, 2006 5:05 am Post subject: drag curve... |
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The prototype has been tested in flight to a top speed of 240 mph IAS (at) 9500 feet that over 270mph TAS, so i am very comfortable with a 210mph Vne for the lightning. Production models, other than N430GH, have shown to be more than 10mph faster than the prototype in a given configuration . the other 2 lightnings that are flying are in West VA and here. Both are in test phase now and lack wheel pants and gear fairings,optimal prop settings,ect.... however when flown at a given power setting ...say 2850 rpm each aircraft so far shows to faster than the prototype...due to cleaner airframe ,finish, better parts fit and a "straighter" much lighter aircraft. All things gained and improved upon in a production model.
Nick Otterback
Brian Whittingham <dashvii(at)hotmail.com> wrote:
[quote]--> Lightning-List message [quote][b]
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cdewey6969(at)yahoo.com
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| Posted: Wed Oct 25, 2006 2:20 pm Post subject: drag curve... |
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What plane is being referred to with a 270 mph TAS?
--- nick otterback <vettin74(at)yahoo.com> wrote:
| Quote: | The prototype has been tested in flight to a top
speed of 240 mph IAS (at) 9500 feet that over 270mph
TAS, so i am very comfortable with a 210mph Vne for
the lightning. Production models, other than N430GH,
have shown to be more than 10mph faster than the
prototype in a given configuration . the other 2
lightnings that are flying are in West VA and here.
Both are in test phase now and lack wheel pants and
gear fairings,optimal prop settings,ect.... however
when flown at a given power setting ...say 2850 rpm
each aircraft so far shows to faster than the
prototype...due to cleaner airframe ,finish, better
parts fit and a "straighter" much lighter aircraft.
All things gained and improved upon in a production
model.
Nick Otterback
Brian Whittingham <dashvii(at)hotmail.com> wrote:
Whittingham"
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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| Quote: |
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dashvii(at)hotmail.com
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| Posted: Sat Oct 28, 2006 6:25 am Post subject: drag curve... |
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Charles,
The plane that Nick was talking about is the Lightning. It has been ran
out to 270mph True Airspeed during the initial testing in the prototype.
Obviously this wasn't in a straight and level flight. As I said, we need at
least a 10% above the published Vne for a built in safety margin when
testing the airplane. At 240mph indicated, Nick would've been more like 20%
over. That's why he said that he feels confident that the plane will do
fine even if we find a way to get 10-15 more mph out of it with airframe
aerodynamic refinements.
Good plane, wide safety margines, good efficiencies, and good speed! I've
given the design for the new hinge fairings to Lamont and as soon as he gets
some time he's going to make the first set and we're going to trial fit them
and make sure we got a tight fit, but good clearance as well. In a couple
of weeks I'll begin flying a series of tests to determine what that
particular plane in that configuration before modification will give us.
Then we'll put on the modifications, probably just the gap seals at first,
then the hinge fairings and test and see what the difference is. After
converting everything back to the standard day I'll tell you what we get in
terms of percent increase or decrease and also give you the numbers. I can
tell you that a series of test have been done on an aftermarket gap seal and
hinge fairing for a Piper Arrow. The arrow has a 1 inch gap in the flaps
whereas the Lightning has a 3 inch gap. I believe that the Arrow also had 6
flap hinges and the Lightning 8. Between that and the fact that the
Lightning is operating at a higher speed range and is a sleaker airframe I
do believe that we'll get better results. If we got the identical increases
as the Arrow we'll gain about 5mph at 75% cruise. That would be bumped up
to about 180mph cruise. Max level speed would be raised to about 195mph.
Again, I think that we'll get even better results. Other results would be
an increase in rate of climb, going by the Arrow example, would give us a
rate of climb of about 50 more feet per minute. We'll see what we get, but
I'll keep you all informed. Brian W.
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cdewey6969(at)yahoo.com
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| Posted: Sat Oct 28, 2006 7:21 am Post subject: drag curve... |
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Brian, Thanks for the informative response. I can't
wait to see your results! Charles
--- Brian Whittingham <dashvii(at)hotmail.com> wrote:
| Quote: |
Whittingham" <dashvii(at)hotmail.com>
Charles,
The plane that Nick was talking about is the
Lightning. It has been ran
out to 270mph True Airspeed during the initial
testing in the prototype.
Obviously this wasn't in a straight and level
flight. As I said, we need at
least a 10% above the published Vne for a built in
safety margin when
testing the airplane. At 240mph indicated, Nick
would've been more like 20%
over. That's why he said that he feels confident
that the plane will do
fine even if we find a way to get 10-15 more mph out
of it with airframe
aerodynamic refinements.
Good plane, wide safety margines, good efficiencies,
and good speed! I've
given the design for the new hinge fairings to
Lamont and as soon as he gets
some time he's going to make the first set and we're
going to trial fit them
and make sure we got a tight fit, but good clearance
as well. In a couple
of weeks I'll begin flying a series of tests to
determine what that
particular plane in that configuration before
modification will give us.
Then we'll put on the modifications, probably just
the gap seals at first,
then the hinge fairings and test and see what the
difference is. After
converting everything back to the standard day I'll
tell you what we get in
terms of percent increase or decrease and also give
you the numbers. I can
tell you that a series of test have been done on an
aftermarket gap seal and
hinge fairing for a Piper Arrow. The arrow has a 1
inch gap in the flaps
whereas the Lightning has a 3 inch gap. I believe
that the Arrow also had 6
flap hinges and the Lightning 8. Between that and
the fact that the
Lightning is operating at a higher speed range and
is a sleaker airframe I
do believe that we'll get better results. If we got
the identical increases
as the Arrow we'll gain about 5mph at 75% cruise.
That would be bumped up
to about 180mph cruise. Max level speed would be
raised to about 195mph.
Again, I think that we'll get even better results.
Other results would be
an increase in rate of climb, going by the Arrow
example, would give us a
rate of climb of about 50 more feet per minute.
We'll see what we get, but
I'll keep you all informed. Brian W.
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