Today's Message Index:
----------------------
1. 12:00 AM - Wiring the SD8 Warning light (Mike Holland)
2. 11:29 AM - Re: SEC: UNCLASSIFIED - STOPPING THE PROP IN AN RV (David Carter)
3. 12:44 PM - Re: SEC: UNCLASSIFIED - STOPPING THE PROP IN (Kevin Horton)
4. 04:26 PM - RG-58/RG-400 (William)
5. 05:56 PM - Re: RG-58/RG-400 (Dave Morris)
6. 06:09 PM - Re: RG-58/RG-400 (Charlie & Tupper England)
7. 06:37 PM - Re: RG-58/RG-400 (John Schroeder)
Message 1
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| Subject: | Wiring the SD8 Warning light |
--> AeroElectric-List message posted by: "Mike Holland" <hollandm@pacbell.net>
I'm wiring the SD8 as a backup alternator. The B&C wiring diagram includes an
alternator warning light fed from the S704 relay, which seemed like a good idea
until I tried to follow Bob's Z13. B&C has you wire the SD8 output to the
battery master bus which turns the warning light off with the master switch,
but if you wire, per Z13, the light remains on regardless since the output is
wired to the battery. Is there any issue/problem in wiring the SD output to
the essential bus so that the light will turn off with the master?
Also, have there been any EMI issues with SD8 subpanel components, including the
regulator, capacitor and relay. I ask since they are relatively close to my
instruments.
Message 2
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| Subject: | Re: SEC: UNCLASSIFIED - STOPPING THE PROP IN AN RV |
--> AeroElectric-List message posted by: "David Carter" <dcarter@datarecall.net>
Good inputs - but we can still do this - will just take more effort: Get
two other planes to go up and fly offset trail at same altitude (#2 plane
flies off of #1/leader). These 2 planes will be "2 points establishing a
line" - hopefully a level one, but if not, at least a ref line. Then, the
guy testing his RV-s flare capability lines up these 2 planes, co speed,
then cuts his engine and holds altitude and holds the two planes in line
(eliminates static error of altimeter as AOA changes/increases) - until he
either successfully stalls in a flare, or starts dropping down below
plane/line of the other 2 before stalling - meaning he lacks adequate
elevator authority to flare to a stall - can only flare to whatever IAS he
read when he started dropping below the other two with full back stick.
- Then install vortex generators under your horizontal stab and repeat
the test to see if elevator authority has been increased.
Personally, I'd think a simple test using the altimeter and V/V would be a
good start, even if slightly flawed by static source error.
David
----- Original Message -----
From: "Kevin Horton" <khorton01@rogers.com>; ; <RV>
Subject: Re: AeroElectric-List: SEC: UNCLASSIFIED - STOPPING THE PROP IN AN
RV
> --> AeroElectric-List message posted by: Kevin Horton
<khorton01@rogers.com> AN RV
>
> It's not quite that easy, unfortunately. First off, ground effect
> comes into play, and it affects the amount of lift the wing produces
> (a bit more lift for the same angle of attack if you are in ground
> effect) and the angle of attack at the stall (the wing will stall at
> a bit lower angle of attack in ground effect than out of ground
> effect). The flow over the tail is also affected, so that affects
> the amount of pitching moment generated for any given elevator
> deflection.
>
> And to make things even more difficult, each RV has its own airspeed
> errors. So 60 kt IAS on your RV may be quite a different speed than
> 60 kt IAS on someone else's RV. This is one reason why you see such
> large differences in the approach speeds that people report using.
>
> And to cap it all off, you have to ask your self how you determine at
> altitude whether you have managed to demonstrate satisfactory pitch
> authority to flare. Are you going to look at the altimeter or VSI to
> see if you manage to level the aircraft? If so, you could be
> mislead, because as you approach the stall there is likely a large
> change in the static source position error, and this will affect the
> altimeter error.
>
> So, simulated flares at altitude are really only a good test in cases
> where the aircraft obviously has way more than enough flare
> capability, or where there is almost zero flare capability. A
> simulated flare at altitude is not a very good test if the real
> capability is somewhere in between zero and huge.
>
> Kevin Horton
>
> >--> AeroElectric-List message posted by: kempthornes
> ><kempthornes@earthlink.net> IN AN RV
> >
> >Who is going to test this at altitude, of course?
> >
> >Go up high, stop the prop, slow to below 60kts and see if there is
adequate
> >elevator authority to flare. Is it that simple to answer this
> >important issue?
> >Probably ought to bring this up to Van too.
> >
> >hal
> >do annual and panel upgrade or I'd do the test.
> >
> >At 06:19 PM 3/17/2004, you wrote:
> >>--> AeroElectric-List message posted by: Kevin Horton
> >><khorton01@rogers.com> AN RV
> >>
> >> >--> AeroElectric-List message posted by: "Francis, David CMDR"
> >> ><David.Francis@defence.gov.au>
> >> >
> >> >Folks,
> >> >Alex Peterson correctly points out that in an RV the prop can stop
below
> >> >60kts.
> >> >
> >> >Not electrical, but this is an important safety issue for RV pilots.
In
> >> >Australia there have been two fatal accidents related to stopped
props. One
> >> >was an RV4, the other an RV6 with tip up canopy, the significance is
that
> >> >both have the rollover bars behind the pilot. Both accidents were
nearly
> >> >identical as follows:
> >> >
> >> >a. both had engine failures after takeoff (one caused by an insecure
fuel
> >> >line, cant remember the other).
> >> >b. both made dead stick approaches to quite reasonable paddocks
upwind of
> >> >the runways.
> >> >c. late in both approaches, speed bled below 60kts and the prop
stopped. In
> >> >RVs this is aerodynamically significant.
> >> >d. at the inboard trailing edge of the wings the fuselage starts to
curve
> >> >away from the wing. At high angles of attack airflow separation
starts at
> >> >this point, and flows aft, over the inboard part of the elevators.
This
> >> >reduces elevator authority, with the prop stopped only. Its fine
> >>with engine
> >> >running.
> >> >e. when flaring both aircraft to land the reduced elevator authority
was
> >> >insufficient to arrest the rate of descent to normal levels. So both
> >> >aircraft landed heavy enough to crush the undercarriage.
> >> >f. without undercarriage the aircraft decelerated at an estimated 4G.
This
> >> >is a very survivable deceleration, but
> >> >g. the longerons at the cockpit buckled outwards, allowing the
> >>rear fuselage
> >> >to move forward and to bend upwards nearly 90 degrees.
> >> >h. the rear fuselage moving forward relaxes the shoulder harness,
allowing
> >> >both pilots to flail forward and receive injuries to the forehead.
> >> >i. as the rear fuselage continued forward the rollover bars crushed
the
> >> >pilots head against the instrument panel. So both died from injuries
to the
> > > >front and back of the head.
> >> >
> >> >Moral of the story, in an RV forced landing you MUST stay over
> >>60kts to keep
> >> >the prop going to avoid loss of elevator authority.
> >> >
> >> >Sorry for long post, its all as described at recent safety seminars
here in
> >> >Australia. The pictures of the wreckage were depressing.
> >> >
> >> >David Francis, VH-ZEE, Canberra, Australia
> >>
> >>Interesting accidents, but I think you have drawn the wrong
> >>conclusion. If the prop is windmilling (i.e. the engine has failed,
> >>but the air is keeping the prop turning), the drag is much higher
> >>than if the prop is stopped. The air actually slows down as it goes
> >>through a windmilling prop. So the inboard wing is likely to stall a
> >>bit earlier than if the prop was stopped, or if the engine was
> >>running. The lower air velocity in the prop wash will also reduce
> >>elevator effectiveness.
> >>
> >>This is the reverse of what happens if the engine is producing power
> >>and it is spinning the prop. In that case the air speeds up as it
> >>goes through the prop, and this increased air velocity helps keep the
> >>inboard wing from stalling, and it increases elevator effectiveness.
> >>
> >>So, the real problem was that the pilots allowed the speed to get too
> >>slow. The fact that the prop stopped actually would have helped
> >>them, but it was not enough of a help to make up for the too slow
> >>speed.
> >>
> >>The real lesson to draw from these accidents is to not let the speed
> >>bleed off below a normal approach speed. Faster is even better.
> >>--
> >>Kevin Horton RV-8 (finishing kit)
> >>Ottawa, Canada
> > >http://go.phpwebhosting.com/~khorton/rv8/
> >>
> > >
>
>
Message 3
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| Subject: | Re: SEC: UNCLASSIFIED - STOPPING THE PROP IN |
AN RV
--> AeroElectric-List message posted by: Kevin Horton <khorton01@rogers.com> AN
RV
Interesting idea, but you need to look at the flare manoeuvre a bit
differently. The flare is much more than just maintaining level
flight. The aircraft has a fairly high rate of descent at the start
of the flare, and you need to "turn the corner" to convert to level
flight. So you are actually pulling a bit more than 1g - typical
flight test data would probably show around 1.1 to 1.15 g in the
flare, a bit more if you are quite aggressive. So, the wing has to
develop enough lift to pull this g, and the elevator has to have
enough authority to create the pitch rate needed.
Let me give you an example of the potential amount of the static
source error, and you will have a better idea of why it matters.
I've got the POH for a 1978 C182Q, and it shows the stall speed with
full flap at max gross weight as 38 KIAS which equals 50 KCAS. That
12 kt error in speed is due to static source position error. It
translates to an altitude error at the stall of 48 ft (altimeter
reading lower than the real altitude). The recommended speed on
final after an engine failure is 65 KIAS, which equates to 67.5 KCAS,
or an altitude error of 15 ft (altimeter reading lower than the real
altitude). So, as you flare, if you are actually maintaining
altitude in the flare, the altimeter will be dropping about 33 ft.
The airspeed will be dropping quite quickly in the flare, so I would
imagine that this change in altitude error would occur over less than
10 seconds. 33 ft in 10 seconds equals a rate of descent of about
200 ft/mn. If the flare lasts 5 seconds, the indicated descent rate
would be about 400 ft/mn. So, just using altimeter and VSI, how do
you determine whether you have been able to arrest the rate of
descent in the flare? Of course the static source errors in an RV
will probably be different than the C182. Will it be more or less?
We don't know.
Keep the speed up to your normal approach speed if you ever have an
engine failure, and there should be no problems at all. Don't be in
too much of a rush to bring the flaps down, as the extra drag may
lead to a tendency for an airspeed loss, unless you lower the nose
aggressively, which leads to a higher rate of descent.
Kevin Horton
>--> AeroElectric-List message posted by: "David Carter"
><dcarter@datarecall.net>
>
>Good inputs - but we can still do this - will just take more effort: Get
>two other planes to go up and fly offset trail at same altitude (#2 plane
>flies off of #1/leader). These 2 planes will be "2 points establishing a
>line" - hopefully a level one, but if not, at least a ref line. Then, the
>guy testing his RV-s flare capability lines up these 2 planes, co speed,
>then cuts his engine and holds altitude and holds the two planes in line
>(eliminates static error of altimeter as AOA changes/increases) - until he
>either successfully stalls in a flare, or starts dropping down below
>plane/line of the other 2 before stalling - meaning he lacks adequate
>elevator authority to flare to a stall - can only flare to whatever IAS he
>read when he started dropping below the other two with full back stick.
> - Then install vortex generators under your horizontal stab and repeat
>the test to see if elevator authority has been increased.
>
>Personally, I'd think a simple test using the altimeter and V/V would be a
>good start, even if slightly flawed by static source error.
>
>David
>
>----- Original Message -----
>From: "Kevin Horton" <khorton01@rogers.com>; ; <RV>
>To: <aeroelectric-list@matronics.com>
>Subject: Re: AeroElectric-List: SEC: UNCLASSIFIED - STOPPING THE PROP IN AN
>RV
>
>
>> --> AeroElectric-List message posted by: Kevin Horton
><khorton01@rogers.com> AN RV
>>
>> It's not quite that easy, unfortunately. First off, ground effect
>> comes into play, and it affects the amount of lift the wing produces
>> (a bit more lift for the same angle of attack if you are in ground
>> effect) and the angle of attack at the stall (the wing will stall at
> > a bit lower angle of attack in ground effect than out of ground
>> effect). The flow over the tail is also affected, so that affects
>> the amount of pitching moment generated for any given elevator
>> deflection.
>>
>> And to make things even more difficult, each RV has its own airspeed
>> errors. So 60 kt IAS on your RV may be quite a different speed than
>> 60 kt IAS on someone else's RV. This is one reason why you see such
>> large differences in the approach speeds that people report using.
>>
>> And to cap it all off, you have to ask your self how you determine at
>> altitude whether you have managed to demonstrate satisfactory pitch
>> authority to flare. Are you going to look at the altimeter or VSI to
>> see if you manage to level the aircraft? If so, you could be
>> mislead, because as you approach the stall there is likely a large
>> change in the static source position error, and this will affect the
>> altimeter error.
>>
>> So, simulated flares at altitude are really only a good test in cases
>> where the aircraft obviously has way more than enough flare
>> capability, or where there is almost zero flare capability. A
>> simulated flare at altitude is not a very good test if the real
>> capability is somewhere in between zero and huge.
>>
>> Kevin Horton
>>
>> >--> AeroElectric-List message posted by: kempthornes
>> ><kempthornes@earthlink.net> IN AN RV
>> >
>> >Who is going to test this at altitude, of course?
>> >
>> >Go up high, stop the prop, slow to below 60kts and see if there is
>adequate
>> >elevator authority to flare. Is it that simple to answer this
>> >important issue?
>> >Probably ought to bring this up to Van too.
>> >
>> >hal
>> >do annual and panel upgrade or I'd do the test.
>> >
>> >At 06:19 PM 3/17/2004, you wrote:
>> >>--> AeroElectric-List message posted by: Kevin Horton
>> >><khorton01@rogers.com> AN RV
>> >>
>> >> >--> AeroElectric-List message posted by: "Francis, David CMDR"
>> >> ><David.Francis@defence.gov.au>
>> >> >
>> >> >Folks,
>> >> >Alex Peterson correctly points out that in an RV the prop can stop
>below
>> >> >60kts.
>> >> >
>> >> >Not electrical, but this is an important safety issue for RV pilots.
>In
>> >> >Australia there have been two fatal accidents related to stopped
>props. One
>> >> >was an RV4, the other an RV6 with tip up canopy, the significance is
>that
>> >> >both have the rollover bars behind the pilot. Both accidents were
>nearly
>> >> >identical as follows:
>> >> >
>> >> >a. both had engine failures after takeoff (one caused by an insecure
>fuel
>> >> >line, cant remember the other).
>> >> >b. both made dead stick approaches to quite reasonable paddocks
>upwind of
>> >> >the runways.
>> >> >c. late in both approaches, speed bled below 60kts and the prop
>stopped. In
>> >> >RVs this is aerodynamically significant.
>> >> >d. at the inboard trailing edge of the wings the fuselage starts to
>curve
>> >> >away from the wing. At high angles of attack airflow separation
>starts at
>> >> >this point, and flows aft, over the inboard part of the elevators.
>This
>> >> >reduces elevator authority, with the prop stopped only. Its fine
>> >>with engine
>> >> >running.
>> >> >e. when flaring both aircraft to land the reduced elevator authority
>was
>> >> >insufficient to arrest the rate of descent to normal levels. So both
>> >> >aircraft landed heavy enough to crush the undercarriage.
>> >> >f. without undercarriage the aircraft decelerated at an estimated 4G.
>This
>> >> >is a very survivable deceleration, but
>> >> >g. the longerons at the cockpit buckled outwards, allowing the
>> >>rear fuselage
>> >> >to move forward and to bend upwards nearly 90 degrees.
>> >> >h. the rear fuselage moving forward relaxes the shoulder harness,
>allowing
>> >> >both pilots to flail forward and receive injuries to the forehead.
>> >> >i. as the rear fuselage continued forward the rollover bars crushed
>the
>> >> >pilots head against the instrument panel. So both died from injuries
>to the
>> > > >front and back of the head.
>> >> >
>> >> >Moral of the story, in an RV forced landing you MUST stay over
>> >>60kts to keep
>> >> >the prop going to avoid loss of elevator authority.
> > >> >
>> >> >Sorry for long post, its all as described at recent safety seminars
>here in
>> >> >Australia. The pictures of the wreckage were depressing.
>> >> >
>> >> >David Francis, VH-ZEE, Canberra, Australia
>> >>
>> >>Interesting accidents, but I think you have drawn the wrong
>> >>conclusion. If the prop is windmilling (i.e. the engine has failed,
>> >>but the air is keeping the prop turning), the drag is much higher
>> >>than if the prop is stopped. The air actually slows down as it goes
>> >>through a windmilling prop. So the inboard wing is likely to stall a
>> >>bit earlier than if the prop was stopped, or if the engine was
>> >>running. The lower air velocity in the prop wash will also reduce
>> >>elevator effectiveness.
>> >>
>> >>This is the reverse of what happens if the engine is producing power
>> >>and it is spinning the prop. In that case the air speeds up as it
>> >>goes through the prop, and this increased air velocity helps keep the
>> >>inboard wing from stalling, and it increases elevator effectiveness.
>> >>
>> >>So, the real problem was that the pilots allowed the speed to get too
>> >>slow. The fact that the prop stopped actually would have helped
>> >>them, but it was not enough of a help to make up for the too slow
>> >>speed.
>> >>
>> >>The real lesson to draw from these accidents is to not let the speed
>> >>bleed off below a normal approach speed. Faster is even better.
>> >>--
>> >>Kevin Horton RV-8 (finishing kit)
>> >>Ottawa, Canada
>> > >http://go.phpwebhosting.com/~khorton/rv8/
>> >>
> > > >
>>
> >
Message 4
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--> AeroElectric-List message posted by: "William" <wschertz@ispwest.com>
Bob, et.al.
When I built my wings and vertical Stab, I embedded antenna's in the
structure using the RG-58 coax, bringing the ends out to the root, where a
connector is attached.
I now read that RG-400 is better, can the balance of the run be RG-400, or
should I stickwith the 58?
Bill Schertz
KIS Cruiser # 4045
Message 5
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| Subject: | Re: RG-58/RG-400 |
--> AeroElectric-List message posted by: Dave Morris <dave@davemorris.com>
It's OK to mix and match coax of similar impedance.
Dave Morris
At 09:42 AM 3/20/2004, you wrote:
>--> AeroElectric-List message posted by: "William" <wschertz@ispwest.com>
>
>Bob, et.al.
>When I built my wings and vertical Stab, I embedded antenna's in the
>structure using the RG-58 coax, bringing the ends out to the root, where a
>connector is attached.
>
>I now read that RG-400 is better, can the balance of the run be RG-400, or
>should I stickwith the 58?
>
>Bill Schertz
>KIS Cruiser # 4045
>
>
Message 6
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| Subject: | Re: RG-58/RG-400 |
--> AeroElectric-List message posted by: Charlie & Tupper England <cengland@netdoor.com>
William wrote:
>--> AeroElectric-List message posted by: "William" <wschertz@ispwest.com>
>
>Bob, et.al.
>When I built my wings and vertical Stab, I embedded antenna's in the
>structure using the RG-58 coax, bringing the ends out to the root, where a
>connector is attached.
>
>I now read that RG-400 is better, can the balance of the run be RG-400, or
>should I stickwith the 58?
>
>Bill Schertz
>KIS Cruiser # 4045
>
Hi Bill,
Either will work fine. They are both 50 ohm; in less than 20 ft the
electrons will never know the difference.
Charlie
Message 7
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| Subject: | Re: RG-58/RG-400 |
--> AeroElectric-List message posted by: John Schroeder <jschroeder@perigee.net>
Bob answered this before. Go ahead and use the RG 400. We did the same
thing.
> When I built my wings and vertical Stab, I embedded antenna's in the
> structure using the RG-58 coax, bringing the ends out to the root, where
> a connector is attached.
>
> I now read that RG-400 is better, can the balance of the run be RG-400,
> or should I stickwith the 58?
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