Today's Message Index:
----------------------
1. 06:52 AM - Dive Tests (923te)
2. 07:37 AM - Re: Dive Tests (Gil Alexander)
3. 08:04 AM - Re: Dive Tests (flyv35b)
4. 11:42 AM - Vne at altitude TAS or IAS? (923te)
5. 12:05 PM - Re: Vne at altitude TAS or IAS? (Gil Alexander)
Message 1
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Gary,
Will an FAA representative be in teh plane with you when you dive it 240 mph
Are you concerned a little about it? We don't want to lose you over some
insidious FAA CYA program.
Here are some comments Fred Kokaska made to me about his dive testing:
".....
In CFR Part 23 certification the term TAS is never defined, recognized or
addressed. They have V speed numbers for everything but all testing,
structural flight testing, climb/cooling flight testing are all related to
IAS.
They will require a correction chart be developed for installation error of
the pitot tube so that test result data is really based on CAS after
observed temp and installation errors are accounted for.
A manufacturer of a new design must define and demonstrate (Vd) (Dive speed
as part of the overall envelope) After demonstrating a dive at Vd the FAA
established Vne (AA5B 174 KCAS) as 90% of demonstrated Vd (FAA takes away
10% as a safety factor) . I went through the Vne part of certification at
100% of Vne for an AA5B (174 KIAS), There were two Part 23 objectives in
this flight test (flown by FAA test pilot) of verifying the prop does not
overspeed (above 2700 RPM) at Vne. This was easy as the back stop in the CS
prop would probably allow 220 KIAS before it ran out of pitch. On a fixed
pitch prop this can be a show stopper and require reducing Vne to prevent
the overspeed. The other was pitch and roll control and airframe vibration.
The test pilot started at 10 K feet and pushed over at full power to
establish 174 KIAS, did some 30 degree left and right rolling maneuvers. He
commented (and I looked out the right side) on the fact the ailerons were
both about 2 inches above the normal even with the flap position in level
flight from airloads. While this looks spooky, he noticed no binding or
control input problems that he did not like.
So, to answer your question .... I have never seen any reference to the term
"TAS" in any certification requirement.
Sombody ought to follow up with the FAA to get the right A/S marking in the
2400 Lb Cheetahs that have the AA5B spar installed. They approved AA5B
airspeed markings for the spar upgrade in Peter Otten's IO-360 STC so you
have an approved example.
Cheers Fred Kokaska"
Stay safe,
Ned
> For-what-it's-worth: B The FAA is making me do carb heat rise tests on my
> new
> cowling. B My cowling has in no way affected the source, path, or
> operation of
> the carb heat. B Their argument: B Since I "MAY" have changed the air
> pressure
> in the lower cowling, I "MAY" have changed the operation of carb heat. B
> SO .
> . . B I tested a stock Tiger. B It doesn't pass the test. B I tested a
> stock
> Tiger with a Power Flow. B It doesn't pass the test either (by 4 degrees).
> B Testing on my new cowling starts as soon as it stops raining.
>
>
> I also have to dive the plane to 240 mph. B But, that's a different story.
> B
>
>
>
Message 2
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Ned... the FAA might only use IAS for testing, but they can change
Vne with altitude (essentially correcting it back to TAS).
The FAA paperwork to certify my Mini-Nimbus sailplane shows this...
Page 4 of the pilots manual supplement has a Vne correction for altitude...
http://www.schempp-hirth.com/fileadmin/tmdocs/328-6-1427.pdf
The correction reduces the IAS for Vne from 135 kts to 120 kts at 19,700 ft
I never bothered certifying my glider (only one in the US did, and
it's a rental) since my operating limitations are so lax,
Experimental, Exhibition and Racing is better...
gil A
At 07:50 AM 1/4/2008, you wrote:
>
>Gary,
>
>Will an FAA representative be in teh plane with you when you dive it 240 mph
>Are you concerned a little about it? We don't want to lose you over
>some insidious FAA CYA program.
>
>Here are some comments Fred Kokaska made to me about his dive testing:
>".....
>In CFR Part 23 certification the term TAS is never defined,
>recognized or addressed. They have V speed numbers for everything
>but all testing, structural flight testing, climb/cooling flight
>testing are all related to IAS.
>They will require a correction chart be developed for installation
>error of the pitot tube so that test result data is really based on
>CAS after observed temp and installation errors are accounted for.
>A manufacturer of a new design must define and demonstrate (Vd)
>(Dive speed as part of the overall envelope) After demonstrating a
>dive at Vd the FAA established Vne (AA5B 174 KCAS) as 90% of
>demonstrated Vd (FAA takes away 10% as a safety factor) . I went
>through the Vne part of certification at 100% of Vne for an AA5B
>(174 KIAS), There were two Part 23 objectives in this flight test
>(flown by FAA test pilot) of verifying the prop does not overspeed
>(above 2700 RPM) at Vne. This was easy as the back stop in the CS
>prop would probably allow 220 KIAS before it ran out of pitch. On a
>fixed pitch prop this can be a show stopper and require reducing Vne
>to prevent the overspeed. The other was pitch and roll control and
>airframe vibration. The test pilot started at 10 K feet and pushed
>over at full power to establish 174 KIAS, did some 30 degree left
>and right rolling maneuvers. He commented (and I looked out the
>right side) on the fact the ailerons were both about 2 inches above
>the normal even with the flap position in level flight from
>airloads. While this looks spooky, he noticed no binding or control
>input problems that he did not like.
>So, to answer your question .... I have never seen any reference to
>the term "TAS" in any certification requirement.
>Sombody ought to follow up with the FAA to get the right A/S marking
>in the 2400 Lb Cheetahs that have the AA5B spar installed. They
>approved AA5B airspeed markings for the spar upgrade in Peter
>Otten's IO-360 STC so you have an approved example.
>
>Cheers Fred Kokaska"
>
>Stay safe,
>
>Ned
>
>
>>For-what-it's-worth: B The FAA is making me do carb heat rise tests on my new
>>cowling. B My cowling has in no way affected the source, path, or
>>operation of
>>the carb heat. B Their argument: B Since I "MAY" have changed the
>>air pressure
>>in the lower cowling, I "MAY" have changed the operation of carb heat. B SO .
>>. . B I tested a stock Tiger. B It doesn't pass the test. B I tested a stock
>>Tiger with a Power Flow. B It doesn't pass the test either (by 4 degrees).
>>B Testing on my new cowling starts as soon as it stops raining.
>>
>>
>>
>>
>>I also have to dive the plane to 240 mph. B But, that's a different story. B
>>
>>
>
>
Message 3
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Vne on a Tiger is 200 mph. Vd would be 222 mph or 200/.9=222. Why the 240
mph. Don't think I would be inclined to go that high!
Cliff
----- Original Message -----
From: Gil Alexander
To: teamgrumman-list@matronics.com
Sent: Friday, January 04, 2008 7:35 AM
Subject: Re: TeamGrumman-List: Dive Tests
Ned... the FAA might only use IAS for testing, but they can change Vne wi
th altitude (essentially correcting it back to TAS).
The FAA paperwork to certify my Mini-Nimbus sailplane shows this...
Page 4 of the pilots manual supplement has a Vne correction for altitude.
..
http://www.schempp-hirth.com/fileadmin/tmdocs/328-6-1427.pdf
The correction reduces the IAS for Vne from 135 kts to 120 kts at 19,700
ft
I never bothered certifying my glider (only one in the US did, and it's a
rental) since my operating limitations are so lax, Experimental, Exhibitio
n and Racing is better...
gil A
At 07:50 AM 1/4/2008, you wrote:
Gary,
Will an FAA representative be in teh plane with you when you dive it 24
0 mph
Are you concerned a little about it=3F We don't want to lose you over som
e insidious FAA CYA program.
Here are some comments Fred Kokaska made to me about his dive testing:
=22.....
In CFR Part 23 certification the term TAS is never defined, recognized
or addressed. They have V speed numbers for everything but all testing, st
ructural flight testing, climb/cooling flight testing are all related to IA
S.
They will require a correction chart be developed for installation erro
r of the pitot tube so that test result data is really based on CAS after o
bserved temp and installation errors are accounted for.
A manufacturer of a new design must define and demonstrate (Vd) (Dive s
peed as part of the overall envelope) After demonstrating a dive at Vd the
FAA established Vne (AA5B 174 KCAS) as 90% of demonstrated Vd (FAA takes aw
ay 10% as a safety factor) . I went through the Vne part of certification a
t 100% of Vne for an AA5B (174 KIAS), There were two Part 23 objectives in
this flight test (flown by FAA test pilot) of verifying the prop does not o
verspeed (above 2700 RPM) at Vne. This was easy as the back stop in the CS
prop would probably allow 220 KIAS before it ran out of pitch. On a fixed p
itch prop this can be a show stopper and require reducing Vne to prevent th
e overspeed. The other was pitch and roll control and airframe vibration. T
he test pilot started at 10 K feet and pushed over at full power to establi
sh 174 KIAS, did some 30 degree left and right rolling maneuvers. He commen
ted (and I looked out the right side) on the fact the ailerons were both ab
out 2 inches above the normal even with the flap position in level flight f
rom airloads. While this looks spooky, he noticed no binding or control inp
ut problems that he did not like.
So, to answer your question .... I have never seen any reference to the
term =22TAS=22 in any certification requirement.
Sombody ought to follow up with the FAA to get the right A/S marking in
the 2400 Lb Cheetahs that have the AA5B spar installed. They approved AA5B
airspeed markings for the spar upgrade in Peter Otten's IO-360 STC so you
have an approved example.
Cheers Fred Kokaska=22
Stay safe,
Ned
For-what-it's-worth: B The FAA is making me do carb heat rise tests o
n my new
cowling. B My cowling has in no way affected the source, path, or ope
ration of
the carb heat. B Their argument: B Since I =22MAY=22 have changed the air
pressure
in the lower cowling, I =22MAY=22 have changed the operation of carb heat
. B SO .
. . B I tested a stock Tiger. B It doesn't pass the test. B I tested
a stock
Tiger with a Power Flow. B It doesn't pass the test either (by 4 degr
ees).
B Testing on my new cowling starts as soon as it stops raining.
I also have to dive the plane to 240 mph. B But, that's a different s
tory. B
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8 3:52 PM
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Message 4
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| Subject: | Vne at altitude TAS or IAS? |
Gil and others,
My last email citing Fred Kokaska was from the middle of a discussion on
Vne at altitude, the subject Gil brought up. I would be interested in
learning more. An article I recieved from Van's started me worrying
about the potential for exceeding Vne at altitude in my Sabre Toothed
Tiger http://www.vansaircraft.com/pdf/hp_limts.pdf
Being that the Tiger certified service ceiling is 13,800 and the
potential for the 260hp Tiger to go much higher, the article caused me
some concern. Especially thinking of making an emergency fast descent
from say 20,000' and whether the Indicated Air Speed on the Air Speed
Indicator would keep me from breaking the Vne....or actually causing a
structural failiure.
I forwarded the article to Ron Levy asking for his input and he had a
good regulations oriented answer and suggested I contact Kokaska to see
how the IO540 STC was stipulated as far as Vne was concerned when he
achieved his STC...you saw part of Fred's answer to me. Between what
Fred and Ron said I concluded not to worry. Here is what Ron said :
Ned:
The article is correct in theory. However, per 14 CFR 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." Therefore, for an aircraft to be certified in the Standard
airworthiness category, either the published VNE is valid up to the book
service ceiling, or this issue would have to be addressed. Further, to
obtain an STC with a bigger engine, the expanded envelope would have to
be addressed or a limitation noted. You might ask Fred Kokaska if this
was covered when they developed the STC.
Ron
In addition to what I quoted earlier Fred also said:
Hello Ron and Ned
Well I read Mr. Krueger's article. I began having problems with his
logic early on when he started by describing the markings on the
airspeed indicator. He refers to Va , the design maneuvering speed as
the "blue line" on the air speed indicator. Wow, that's news to me as Va
is not required and never shown as a "limit"on the airspeed indicator.
Multi-engine aircraft have an airspeed indicator blue line which
represents Vyse (best single engine rate-of-climb speed).
The writer lost a few points right there.........
>
In CFR Part 23 certification the term TAS is never defined, recognized
or addressed. They have V speed numbers for everything but all testing,
structural flight testing, climb/cooling flight testing are all related
to IAS.
They will require a correction chart be developed for installation error
of the pitot tube so that test result data is really based on CAS after
observed temp and installation errors are accounted for.
A manufacturer of a new design must define and demonstrate (Vd) (Dive
speed as part of the overall envelope) After demonstrating a dive at Vd
the FAA established Vne (AA5B 174 KCAS) as 90% of demonstrated Vd (FAA
takes away 10% as a safety factor) . I went through the Vne part of
certification at 100% of Vne for an AA5B (174 KIAS), There were two Part
23 objectives in this flight test (flown by FAA test pilot) of verifying
the prop does not overspeed (above 2700 RPM) at Vne. This was easy as
the back stop in the CS prop would probably allow 220 KIAS before it ran
out of pitch. On a fixed pitch prop this can be a show stopper and
require reducing Vne to prevent the overspeed. The other was pitch and
roll control and airframe vibration. The test pilot started at 10 K
feet and pushed over at full power to establish 174 KIAS, did some 30
degree left and right rolling maneuvers. He commented (and I looked out
the right side) on the fact the ailerons were both about 2 inches above
the normal even with the flap position in level flight from airloads.
While this looks spooky, he noticed no binding or control input problems
that he did not like.
So, to answer your question .... I have never seen any reference to the
term "TAS" in any certification requirement.
Sombody ought to follow up with the FAA to get the right A/S marking in
the 2400 Lb Cheetahs that have the AA5B spar installed. They approved
AA5B airspeed markings for the spar upgrade in Peter Otten's IO-360 STC
so you have an approved example.
Cheers Fred Kokaska
What do you think,?
Ned
Message 5
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| Subject: | Re: Vne at altitude TAS or IAS? |
>.......
>Ron
>
>In addition to what I quoted earlier Fred also said:
>Hello Ron and Ned
>Well I read Mr. Krueger's article. I began having problems with his
>logic early on when he started by describing the markings on the
>airspeed indicator. He refers to Va , the design maneuvering speed
>as the "blue line" on the air speed indicator. Wow, that's news to
>me as Va is not required and never shown as a "limit"on the airspeed
>indicator. Multi-engine aircraft have an airspeed indicator blue
>line which represents Vyse (best single engine rate-of-climb speed).
>The writer lost a few points right there.........
Don't knock any points off here...
The article was written by one Van for his own customers (RV builders
and owners), and Van does make a big deal of the Va speed since it is
relatively easy to damage a RV with the stick at normal cruise speeds...
All of the airspeed indicators Van sells DO have a blue line on them...
Just consider who the article was written for, and the fact that RVs
do not have to meet "standard" FAA stuff...
Ken Krueger is part of Vans Technical Support staff...
http://www.vansaircraft.com/public/pers-gen.htm
gil A
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