"Interesting" wind yesterday

"Jim" wrote in message
news
On Wed, 09 Mar 2005 21:52:58 GMT, "Mike Rapoport"
wrote:


"T o d d P a t t i s t" wrote in message
. ..
"Mike Rapoport" wrote:

I've never heard of Vne being related to TAS, only IAS. It makes no
sense
to me. Could you provide a reference?

Vne is a fixed mark on the airspeed indicator and,
as such, doesn't move.

Despite the Vne mark on the altimeter, it definitely is not
a fixed IAS (or CAS) number. Nor is it always a fixed TAS
number. It is the number defined by the manufacturer that
is usually found in the flight manual. My sailplane has a
Vne that drops with altitude, and while it's closer to a
fixed TAS than IAS, it's not exactly either.

A fixed TAS makes sense because it is often flutter that
sets the Vne limit, and flutter is a timing related issue
that relates to TAS more closely than IAS.

"It is possible to fly without motors, but not without knowledge and
skill."
Wilbur Wright

So what is the mark on the airspeed indicator supposed to mean then? I
have
never seen anything in any of the flight manuals that I have (four)
referring to Vne going down with altitude. I am not disputing that it
does
but I am mystified as to why it isn't better explained in flight manuals.
Similiarly, Vmo is given as a single IAS number. In the MU-2 Vmo is
250kts
IAS at any altitude up to about 22,000' where the Mach limit takes over.
This is a large range of TAS. Is it perhaps actually related to Mmo
rather
than Vne as gliders don't have airspeed indicators with barber poles? Can
you give some examples wth real numbers and altitudes?

Mike
MU-2


Here is the information from the Flight Manual for the DG-500 glider.

Section 4.5.9 Flight at high altitude and at low temperatures:

...

2. Attention must be paid to the fact that at higher
altitudes the true airspeed is greater than the
indicated airspeed.
The max. speed Vne is reduced. See the
following table:

...

Altitude in ft. 0-6600 10000 13000 16000 20000
Vne IAS kts. 146 138 131 124
117

Hope this helps.



Thanks, it does. The question of what the red mark on powered airplanes
means remains. Is it Vne at the aircraft's ceiling? If it is Vne at sea
level then there should be some language in the flight manual warning of
this.

The reference to low temperatures is also interesting. Is the strength of
the glider's resin reduced at low temperatures?

Mike
MU-2

"Mike Rapoport" wrote
Thanks, it does. The question of what the red mark on powered
airplanes means remains. Is it Vne at the aircraft's ceiling? If it
is Vne at sea level then there should be some language in the flight
manual warning of this.

Mike... this is from 23.1545

(c) If VNE or VNO vary with altitude, there must be means to indicate to
the pilot the appropriate limitations throughout the operating altitude
range.

(d) Paragraphs (b)(1) through (b)(3) and paragraph (c) of this section do
not apply to aircraft for which a maximum operating speed VMO/MMO is
established under §23.1505(c). For those aircraft there must either be a
maximum allowable airspeed indication showing the variation of VMO/MMO with
altitude or compressibility limitations (as appropriate), or a radial red
line marking for VMO/MMO must be made at lowest value of VMO/MMO
established for any altitude up to the maximum operating altitude for the
airplane.

Bob Moore

Mike,
I don't know if it will help, but you may find some guidence in part 23.1505
and 23.335. I started to read through it and the only thing I ended up with
was a headache.

Jim Burns
(the other Jim)

"Mike Rapoport" wrote in message
ink.net...

"Jim" wrote in message

Thanks, it does. The question of what the red mark on powered airplanes
means remains. Is it Vne at the aircraft's ceiling? If it is Vne at sea
level then there should be some language in the flight manual warning of
this.

The reference to low temperatures is also interesting. Is the strength of
the glider's resin reduced at low temperatures?

Mike
MU-2

On Thu, 10 Mar 2005 15:22:53 GMT, "Mike Rapoport"
wrote:


"Jim" wrote in message
news
On Wed, 09 Mar 2005 21:52:58 GMT, "Mike Rapoport"
wrote:


"T o d d P a t t i s t" wrote in message
...
"Mike Rapoport" wrote:

I've never heard of Vne being related to TAS, only IAS. It makes no
sense
to me. Could you provide a reference?

Vne is a fixed mark on the airspeed indicator and,
as such, doesn't move.

Despite the Vne mark on the altimeter, it definitely is not
a fixed IAS (or CAS) number. Nor is it always a fixed TAS
number. It is the number defined by the manufacturer that
is usually found in the flight manual. My sailplane has a
Vne that drops with altitude, and while it's closer to a
fixed TAS than IAS, it's not exactly either.

A fixed TAS makes sense because it is often flutter that
sets the Vne limit, and flutter is a timing related issue
that relates to TAS more closely than IAS.

"It is possible to fly without motors, but not without knowledge and
skill."
Wilbur Wright

So what is the mark on the airspeed indicator supposed to mean then? I
have
never seen anything in any of the flight manuals that I have (four)
referring to Vne going down with altitude. I am not disputing that it
does
but I am mystified as to why it isn't better explained in flight manuals.
Similiarly, Vmo is given as a single IAS number. In the MU-2 Vmo is
250kts
IAS at any altitude up to about 22,000' where the Mach limit takes over.
This is a large range of TAS. Is it perhaps actually related to Mmo
rather
than Vne as gliders don't have airspeed indicators with barber poles? Can
you give some examples wth real numbers and altitudes?

Mike
MU-2


Here is the information from the Flight Manual for the DG-500 glider.

Section 4.5.9 Flight at high altitude and at low temperatures:

...

2. Attention must be paid to the fact that at higher
altitudes the true airspeed is greater than the
indicated airspeed.
The max. speed Vne is reduced. See the
following table:

...

Altitude in ft. 0-6600 10000 13000 16000 20000
Vne IAS kts. 146 138 131 124
117

Hope this helps.



Thanks, it does. The question of what the red mark on powered airplanes
means remains. Is it Vne at the aircraft's ceiling? If it is Vne at sea
level then there should be some language in the flight manual warning of
this.

The reference to low temperatures is also interesting. Is the strength of
the glider's resin reduced at low temperatures?

Mike
MU-2


Here is the text relating to low tempertures from the flight manual:

With temperatures below 0 degrees C (32 F), for instance
when wave flying or flying in winter, it is possible that the
control circuits could become stiffer. Special care
should be taken to ensure that there is no moisture on
any section of the control circuits to minimize the
possibility of freeze up.
It could be advantageous to apply vaseline along
all the edges of the airbrake cover plates to
minimize the possibility of freezing closed.

Also, item 1, which I did not include in my previous reply states:

1. At termperatures below -20 degrees C ( -4F) there
is the risk of cracking the gelcoat.

I don't think the glider's structure would really suffer damage
though.

OK, this makes sense. It is simpler to position the red mark for the most
conservative conditions than to have a varying Vne. In gliders, often used
for racing, it makes sense to provide the pilot with the actual Vne which
varies with altitude so that they can extract maximium performance.

Mike
MU-2



"T o d d P a t t i s t" wrote in message
...
"Mike Rapoport" wrote:

Vne is a fixed mark on the airspeed indicator and,
as such, doesn't move.

Despite the Vne mark on the altimeter, it definitely is not
a fixed IAS (or CAS) number. Nor is it always a fixed TAS
number. It is the number defined by the manufacturer that
is usually found in the flight manual.
Wilbur Wright

So what is the mark on the airspeed indicator supposed to mean then?

Good question. Here's the rule:

FAA Federal Aviation Regulations (FARS, 14 CFR)
23.1545 - Airspeed indicator

(a) Each airspeed indicator must be marked as specified
[including Vne] ...

(c) If VNE or VNO vary with altitude, there must be means to
indicate to the pilot the appropriate limitations throughout
the operating altitude range.

I suspect the compliance method used is to put the limits in
the handbook and put a placard in the aircraft. That's how
it's done in mine.

Here's the rule when VMO/MMO applies and Vne does not:

(d) ... For those aircraft there must either be a maximum
allowable airspeed indication showing the variation of
VMO/MMO with altitude or compressibility limitations (as
appropriate), or a radial red line marking for VMO/MMO must
be made at lowest value of VMO/MMO established for any
altitude up to the maximum operating altitude for the
airplane.

My Vne red line is the speed at sea level, and it begins to
drop above 10,000' per the placard and flight manual.

I have
never seen anything in any of the flight manuals that I have (four)
referring to Vne going down with altitude. I am not disputing that it
does
but I am mystified as to why it isn't better explained in flight manuals.

If it's not placarded and doesn't appear in the flight
manual, you can assume the red line is correct up to maximum
operating altitude. Of course, you can fly airplanes above
service ceiling with some help from nature (wave lift comes
to mind), just as you can fly a glider, so you still want to
be aware of the common altitude dependency of Vne. You
can't really assume anything about Vne except when flying
within the limits.



"It is possible to fly without motors, but not without knowledge and
skill."
Wilbur Wright

"Bob Moore" wrote in message
. 121...
"Mike Rapoport" wrote
Thanks, it does. The question of what the red mark on powered
airplanes means remains. Is it Vne at the aircraft's ceiling? If it
is Vne at sea level then there should be some language in the flight
manual warning of this.

Mike... this is from 23.1545

(c) If VNE or VNO vary with altitude, there must be means to indicate to
the pilot the appropriate limitations throughout the operating altitude
range.

(d) Paragraphs (b)(1) through (b)(3) and paragraph (c) of this section do
not apply to aircraft for which a maximum operating speed VMO/MMO is
established under §23.1505(c). For those aircraft there must either be a
maximum allowable airspeed indication showing the variation of VMO/MMO
with
altitude or compressibility limitations (as appropriate), or a radial red
line marking for VMO/MMO must be made at lowest value of VMO/MMO
established for any altitude up to the maximum operating altitude for the
airplane.

Bob Moore

Thanks for the reference. It makes sense now.

Mike
MU-2

Thanks Jim. The gliders used for wave soaring at Minden all had cracked gel
coats on the underside of the wing and some had cracking on the upper
surface too.

Mike
MU-2

"Jim" wrote in message
...
On Thu, 10 Mar 2005 15:22:53 GMT, "Mike Rapoport"
wrote:


"Jim" wrote in message
news
On Wed, 09 Mar 2005 21:52:58 GMT, "Mike Rapoport"
wrote:


"T o d d P a t t i s t" wrote in message
m...
"Mike Rapoport" wrote:

I've never heard of Vne being related to TAS, only IAS. It makes no
sense
to me. Could you provide a reference?

Vne is a fixed mark on the airspeed indicator and,
as such, doesn't move.

Despite the Vne mark on the altimeter, it definitely is not
a fixed IAS (or CAS) number. Nor is it always a fixed TAS
number. It is the number defined by the manufacturer that
is usually found in the flight manual. My sailplane has a
Vne that drops with altitude, and while it's closer to a
fixed TAS than IAS, it's not exactly either.

A fixed TAS makes sense because it is often flutter that
sets the Vne limit, and flutter is a timing related issue
that relates to TAS more closely than IAS.

"It is possible to fly without motors, but not without knowledge and
skill."
Wilbur Wright

So what is the mark on the airspeed indicator supposed to mean then? I
have
never seen anything in any of the flight manuals that I have (four)
referring to Vne going down with altitude. I am not disputing that it
does
but I am mystified as to why it isn't better explained in flight
manuals.
Similiarly, Vmo is given as a single IAS number. In the MU-2 Vmo is
250kts
IAS at any altitude up to about 22,000' where the Mach limit takes over.
This is a large range of TAS. Is it perhaps actually related to Mmo
rather
than Vne as gliders don't have airspeed indicators with barber poles?
Can
you give some examples wth real numbers and altitudes?

Mike
MU-2


Here is the information from the Flight Manual for the DG-500 glider.

Section 4.5.9 Flight at high altitude and at low temperatures:

...

2. Attention must be paid to the fact that at higher
altitudes the true airspeed is greater than the
indicated airspeed.
The max. speed Vne is reduced. See the
following table:

...

Altitude in ft. 0-6600 10000 13000 16000 20000
Vne IAS kts. 146 138 131 124
117

Hope this helps.



Thanks, it does. The question of what the red mark on powered airplanes
means remains. Is it Vne at the aircraft's ceiling? If it is Vne at sea
level then there should be some language in the flight manual warning of
this.

The reference to low temperatures is also interesting. Is the strength of
the glider's resin reduced at low temperatures?

Mike
MU-2


Here is the text relating to low tempertures from the flight manual:

With temperatures below 0 degrees C (32 F), for instance
when wave flying or flying in winter, it is possible that the
control circuits could become stiffer. Special care
should be taken to ensure that there is no moisture on
any section of the control circuits to minimize the
possibility of freeze up.
It could be advantageous to apply vaseline along
all the edges of the airbrake cover plates to
minimize the possibility of freezing closed.

Also, item 1, which I did not include in my previous reply states:

1. At termperatures below -20 degrees C ( -4F) there
is the risk of cracking the gelcoat.

I don't think the glider's structure would really suffer damage
though.