Today's Message Index:
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1. 02:16 AM - Re: Vne Speed (William Harrison)
2. 05:27 AM - Re: Vne Speed (Andrew Sarangan)
3. 11:53 AM - Vne speed (=?UTF-8?Q?R=C3=A9mi_Guerner?=)
4. 12:30 PM - Re: Vne Speed (Pete Lawless)
5. 01:30 PM - Re: Vne speed (Sidsel & Svein Johnsen)
6. 01:41 PM - Re: Vne speed (William Daniell)
7. 01:54 PM - Re: Vne Speed (Gerry Cole)
8. 03:12 PM - Re: Vne Speed (Jan de Jong)
9. 03:13 PM - Re: Vne Speed (Jan de Jong)
10. 03:28 PM - Re: Vne Speed (Rob Housman)
Message 1
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I suggest there are several golden rules here:
1. Never, ever, exceed the Never Exceed Speed of 165 kts. (Question
for better aerodynamicists than me: should this be taken as 165 RAS
since that is the direct indication of the aerodynamic load?? In
practice, the big red line on the IAS scale is what we abide by in
practice.)
2. Be super gentle pulling out of a Vne speed dive (eg as we have to
do for Permit renewal in the UK - not sure whether there's an
equivalent routine flight test elsewhere). That means plenty of
height so that a modest positive g force will recover to straight and
level flight with plenty to spare.
3. Abide by Va (97kts for Europa) and Vno 131 kts for Europa) and Vfe
(83 kts for Europa) limitations (definitions below):
VA
design maneuvering speed (stalling speed at the maximum legal G-
force, and hence the maximum speed at which abrupt, full deflection,
control inputs will not cause the aircraft to exceed its G-force
limit). Maneuvering speed is limited by aircraft structural
characteristics.
VNO
maximum structural cruising speed (the maximum speed to be used in
turbulent conditions) or can refer to the velocity of normal
operation. VNO is specified as the upper limit of the green arc on
many airspeed indicators. This speed is specific to the aircraft
model. The range above VNO is marked on the airspeed indicator as a
yellow arc from VNO to the VNE
VFE
Max speed for flap extension
4. Be wary of Brochure performance claims.
Willie Harrison G-BZNY
On 12 Dec 2006, at 23:25, Graham Singleton wrote:
> <grahamsingleton@btinternet.com>
>
> Jim
> RAS is I assume Rectified Air Speed. Corrected for instrument and
> position errors. (The position of the static and pitot sensors. )
> TAS ( true air speed ) is IAS corrected for altitude and
> temperature and it will usually be higher, so you could still be
> below Vne.
> Graham
>
> h&jeuropa wrote:
>
>> <europa@triton.net>
>>
>> I have recently become aware that Vne is normally expressed in
>> True Airspeed (TAS). According to Derek Piggott=92s Gliding text,
>> =93it is important to limit indicated airspeed so the true airspeed
>> is kept below the Vne placard speed. Otherwise there may be risk
>> of flutter and structural failure=94.
>>
>> My XS Owner=92s Manual states that Vne is 165 kts (page 2-1, issue
>> 1). The same manual states that for a 914 typical performance is
>> Cruise speed (100% @ 10,000 ft) 170 kts TAS (page 12-2, issue 1).
>> But that is 5 kts greater than Vne!! That page also states Top
>> Speed (sea level) 144 kts RAS. What is RAS? Is it a typing
>> error (R is adjacent to T on a keyboard)? RAS is also referred to
>> on the 912 performance page.
>>
>> What are the performance numbers for the MG? Brochure says 151
>> kts TAS max cruise speed for 914 at 10000 ft. So is 151 KTAS Vne?
>>
>> It is very easy to exceed 165 KTAS when descending from altitude.
>> Should this be avoided?
>> Jim Butcher XS N241BW
>>
>>
>>
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=81100#81100
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
Message 2
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RAS is not a commonly used term, but it means Rectified Airspeed, which
is the same as Calibrated Airspeed (CAS). CAS is the Airspeed corrected
for installation errors.
--- "h&jeuropa" <europa@triton.net> wrote:
> <europa@triton.net>
>
> I have recently become aware that Vne is normally expressed in True
> Airspeed (TAS). According to Derek Piggotts Gliding text, it
> is important to limit indicated airspeed so the true airspeed is kept
> below the Vne placard speed. Otherwise there may be risk of flutter
> and structural failure.
>
> My XS Owners Manual states that Vne is 165 kts (page 2-1, issue
> 1). The same manual states that for a 914 typical performance is
> Cruise speed (100% @ 10,000 ft) 170 kts TAS (page 12-2, issue 1).
> But that is 5 kts greater than Vne!! That page also states Top Speed
> (sea level) 144 kts RAS. What is RAS? Is it a typing error (R is
> adjacent to T on a keyboard)? RAS is also referred to on the 912
> performance page.
>
> What are the performance numbers for the MG? Brochure says 151 kts
> TAS max cruise speed for 914 at 10000 ft. So is 151 KTAS Vne?
>
> It is very easy to exceed 165 KTAS when descending from altitude.
> Should this be avoided?
>
> Jim Butcher
> XS N241BW
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=81100#81100
>
>
>
>
>
>
>
>
>
>
>
Andrew Sarangan
http://www.sarangan.org
Message 3
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Hi Jim,
This is absolutely wrong. All airspeed limitations are IAS, Indicated AirSpeeds.
On the other hand, all performances figures are TAS, True AirSpeed.
Besides the instrument error, what your Pitot is senses and what your anemometer
indicates is exactly what affects the load on the structure of the aircraft.
Suppose you are doing 170kts True AirSpeed at 10000 feet. The density at this
altitude in standard atmosphere is 0.74. Your Indicated Air Speed will be 170
multiplied by the square root of the density, i.e 0.86, so your anemometer
will indicate 146 kts, which is far enough from Vne.
Remi Guerner
F-PGKL
Subject: Europa-List: Vne Speed
From: "h&jeuropa" <europa@triton.net>
I have recently become aware that Vne is normally expressed in True Airspeed (TAS).
According to Derek Piggotts Gliding text, it is important to limit indicated
airspeed so the true airspeed is kept below the Vne placard speed. Otherwise
there may be risk of flutter and structural failure.
My XS Owners Manual states that Vne is 165 kts (page 2-1, issue 1). The same manual
states that for a 914 typical performance is Cruise speed (100% @ 10,000
ft) 170 kts TAS (page 12-2, issue 1). But that is 5 kts greater than Vne!!
That page also states Top Speed (sea level) 144 kts RAS. What is RAS? Is it
a typing error (R is adjacent to T on a keyboard)? RAS is also referred to on
the 912 performance page.
What are the performance numbers for the MG? Brochure says 151 kts TAS max cruise
speed for 914 at 10000 ft. So is 151 KTAS Vne?
It is very easy to exceed 165 KTAS when descending from altitude. Should this
be avoided?
Jim Butcher
XS N241BW
Message 4
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IAS is what you see on the ASI
CAS is IAS corrected for instrument error, errors in manufacture or calibration
RAS is CAS corrected for Position Error
EAS is RAS corrected for compressibility Error
(only applicable to 200 hp turbo charged Europas)
-----Original Message-----
From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com] On Behalf Of Andrew Sarangan
Sent: 13 December 2006 13:26
Subject: Re: Europa-List: Vne Speed
RAS is not a commonly used term, but it means Rectified Airspeed, which
is the same as Calibrated Airspeed (CAS). CAS is the Airspeed corrected
for installation errors.
--- "h&jeuropa" <europa@triton.net> wrote:
> <europa@triton.net>
>
> I have recently become aware that Vne is normally expressed in True
> Airspeed (TAS). According to Derek Piggotts Gliding text, it
> is important to limit indicated airspeed so the true airspeed is kept
> below the Vne placard speed. Otherwise there may be risk of flutter
> and structural failure.
>
> My XS Owners Manual states that Vne is 165 kts (page 2-1, issue
> 1). The same manual states that for a 914 typical performance is
> Cruise speed (100% @ 10,000 ft) 170 kts TAS (page 12-2, issue 1).
> But that is 5 kts greater than Vne!! That page also states Top Speed
> (sea level) 144 kts RAS. What is RAS? Is it a typing error (R is
> adjacent to T on a keyboard)? RAS is also referred to on the 912
> performance page.
>
> What are the performance numbers for the MG? Brochure says 151 kts
> TAS max cruise speed for 914 at 10000 ft. So is 151 KTAS Vne?
>
> It is very easy to exceed 165 KTAS when descending from altitude.
> Should this be avoided?
>
> Jim Butcher
> XS N241BW
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=81100#81100
>
>
>
>
>
>
>
>
>
>
>
Andrew Sarangan
http://www.sarangan.org
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Message 5
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All,
The reference for Vne is CAS (calibrated air speed), not IAS by
definition. If your ASI has been properly calibrated, you read it off
the instrument as equal to IAS.
As to the Vne verification (not test - that's implying it's too risky),
Andy Draper gave me this good recommendation while he was still at
Europa's (starting with the issue of flutter test, which is NOT
recommended):
quote
I would recommend that you do conduct a dive to Vne during your test
flying, but only after you have calibrated your ASI. At Vne you should
move the stick in pitch and roll by a small amount and separately and
also the rudder, but not necessarily tap them. This tapping is a
technique to try to excite flutter where there is a tendency for it to
happen and usually need only be done when establishing the flight
characteristics of a new design. You will be more concerned to check
that the forces have increased with increased speed and that there is
still a tendency for the controls to self centre. It would be most
unlikely that your aircraft does not comply, as the Europa design has
been fully tried and tested.
In the UK, this 'Vne dive' is conducted at each annual flight test. The
favoured technique is to fly and trim at a high cruise speed, say 130kts
level, then progressively pitch down and reduce throttle to
approximately 1/3 open. Carefully monitor the ASI and be careful not to
accellerate beyond Vne. Anticipate Vne by about 5 knots by relaxing
forward pressure. Don't attempt to trim for Vne. When you relax the
forward pressure the aircraft will revert to a climb and slow reasonably
quickly.
unquote
Nedless to say: No wind sheer and no turbulense when this verification
is performed!
Best regards,
Svein
LN-SKJ
Message 6
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This is my understanding also everything in Vspeeds is IAS otherwise you
would have to get you E6b out in the middle of a maneuver=85
_____
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of R=E9mi
Guerner
Sent: Wednesday, December 13, 2006 14:52
Subject: Europa-List: Vne speed
Hi Jim,
This is absolutely wrong. All airspeed limitations are IAS, Indicated
AirSpeeds. On the other hand, all performances figures are TAS, True
AirSpeed.
Besides the instrument error, what your Pitot is senses and what your
anemometer indicates is exactly what affects the load on the structure
of
the aircraft. Suppose you are doing 170kts True AirSpeed at 10000 feet.
The
density at this altitude in standard atmosphere is 0.74. Your Indicated
Air
Speed will be 170 multiplied by the square root of the density, i.e
0.86, so
your anemometer will indicate 146 kts, which is far enough from Vne.
Remi Guerner
F-PGKL
Subject: Europa-List: Vne Speed
From: "h&jeuropa" < <mailto:europa@triton.net> europa@triton.net>
I have recently become aware that Vne is normally expressed in True
Airspeed
(TAS).
According to Derek Piggotts Gliding text, it is important to limit
indicated
airspeed so the true airspeed is kept below the Vne placard speed.
Otherwise
there may be risk of flutter and structural failure.
My XS Owners Manual states that Vne is 165 kts (page 2-1, issue 1). The
same manual
states that for a 914 typical performance is Cruise speed (100% @ 10,000
ft) 170 kts TAS (page 12-2, issue 1). But that is 5 kts greater than
Vne!!
That page also states Top Speed (sea level) 144 kts RAS. What is RAS?
Is
it
a typing error (R is adjacent to T on a keyboard)? RAS is also referred
to
on
the 912 performance page.
What are the performance numbers for the MG? Brochure says 151 kts TAS
max
cruise
speed for 914 at 10000 ft. So is 151 KTAS Vne?
It is very easy to exceed 165 KTAS when descending from altitude.
Should
this
be avoided?
Jim Butcher
XS N241BW
Message 7
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Jim,
If my memory is correct speeds are defined as follows:
Indicated Airspeed (IAS) = Instrument reading corrected for instrument
(mechanical) error.
Rectified Airspeed (RAS) is the 1940's British equivalent of the
American Calibrated Airspeed (CAS). They both equal Instrument reading
corrected for instrument error and position (pressure) error( I think
there is some difference between the two at high speeds and altitudes).
If you are lucky, on our kind of aeroplane there won't be too much
difference between IAS and RAS or CAS.
Both RAS and CAS are close to the scientifically pure Equivalent
Airspeed (EAS).
EAS = True Airspeed (TAS) x the square root of the relative air
density. On a Standard day (15 deg C at sealevel falling at a little
under 2 deg C per 1000ft up to 36000ft) EAS equals TAS at sealevel, but
at 10,000 ft an EAS of 150kts is equivalent to a TAS of 174.5kts.
I could be wrong but I thought design manoeuvring envelopes were
defined in EAS and cockpit placards showed IAS.
Gerry Cole , Classic 121
----- Original Message -----
From: h&jeuropa
I have recently become aware that Vne is normally expressed in True
Airspeed (TAS). ?
Jim Butcher
XS N241BW
List Contribution Web Site
Message 8
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>
>
>I have recently become aware that Vne is normally expressed in True Airspeed (TAS).
>
I don't believe this. Aerodynamic forces are a function of CAS, not TAS.
Regards,
Jan de Jong
Message 9
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>
>
>I have recently become aware that Vne is normally expressed in True Airspeed (TAS).
>
Sorry, I should have done a search.
Apparently aeodynamic forces are not all there is to Vne - the sheer
velocity of the air is a factor too.
Interesting - didn't know.
Regards,
Jan de Jong
Message 10
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AOPA members can check this out at
http://www.aopa.org/members/files/flttrain/aeronautical_knowledge/8083-25_ch
ap9.pdf
but the relevant definitions from the Pilot's Handbook of Aeronautical
Knowledge 2003 (FAA-H-8083-25) are quoted below:
True Airspeed (TAS) the speed of the airplane in relation to the air mass
in which it is flying.
Indicated Airspeed (IAS) the speed of the airplane as observed on the
airspeed indicator. It is the airspeed without correction for indicator,
position (or installation), or compressibility errors.
Calibrated Airspeed (CAS) the airspeed indicator reading corrected for
position (or installation), and instrument errors. (CAS is equal to TAS at
sea level in standard atmosphere.) The color-coding for various design
speeds marked on airspeed indicators may be IAS or CAS.
Equivalent Airspeed (EAS) the airspeed indicator reading corrected for
position (or installation), or instrument error, and for adiabatic
compressible flow for the particular altitude. (EAS is equal to CAS at sea
level in standard atmosphere.)
VA the calibrated design maneuvering airspeed. This is the maximum speed
at which the limit load can be imposed (either by gusts or full deflection
of the control surfaces) without causing structural damage.
VNO the maximum calibrated airspeed for normal operation or the maximum
structural cruising speed. This is the speed at which exceeding the limit
load factor may cause permanent deformation of the airplane structure.
VNE the calibrated airspeed which should NEVER be exceeded. If flight is
attempted above this speed, structural damage or structural failure may
result.
VSO, VS1, VX, VY, VLE, VFO, and VFE, are ALL in CAS. The FAA does not
mention RAS in this publication, probably because that term is not common on
this side of the Atlantic.
Best regards,
Rob Housman
A070
Airframe complete
Irvine, CA
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com]On Behalf Of Gerry Cole
Sent: Wednesday, December 13, 2006 1:52 PM
Subject: Re: Europa-List: Vne Speed
Jim,
If my memory is correct speeds are defined as follows:
Indicated Airspeed (IAS) = Instrument reading corrected for instrument
(mechanical) error.
Rectified Airspeed (RAS) is the 1940's British equivalent of the American
Calibrated Airspeed (CAS). They both equal Instrument reading corrected for
instrument error and position (pressure) error( I think there is some
difference between the two at high speeds and altitudes).
If you are lucky, on our kind of aeroplane there won't be too much
difference between IAS and RAS or CAS.
Both RAS and CAS are close to the scientifically pure Equivalent Airspeed
(EAS).
EAS = True Airspeed (TAS) x the square root of the relative air density. On
a Standard day (15 deg C at sealevel falling at a little under 2 deg C per
1000ft up to 36000ft) EAS equals TAS at sealevel, but at 10,000 ft an EAS of
150kts is equivalent to a TAS of 174.5kts.
I could be wrong but I thought design manoeuvring envelopes were defined in
EAS and cockpit placards showed IAS.
Gerry Cole , Classic 121
----- Original Message -----
From: h&jeuropa <mailto:europa@triton.net>
I have recently become aware that Vne is normally expressed in True Airspeed
(TAS). ?
Jim Butcher
XS N241BW
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