Today's Message Index:
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1. 07:16 AM - Re: How to Toggle Speed Brakes with Momentary On Switch? (mmayfield)
2. 07:45 AM - Re: Re: How to Toggle Speed Brakes with Momentary On Switch? (K)
3. 08:21 AM - Re: Re: How to Toggle Speed Brakes with Momentary On Switch? (Valin & Allyson Thorn)
4. 10:26 AM - Spoilers vs. Speed Brakes (Dennis Johnson)
Message 1
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| Subject: | Re: How to Toggle Speed Brakes with Momentary On Switch? |
nuckolls.bob(at)aeroelect wrote:
>
> Suggest you purge the term "speed brake" from your
> language used to talk about this system. It's
> a spoiler system that kills lift . . . designed to
> INCRASE rate of descent without materially
> increasing forward velocity. A speed brake puts
> out DRAG intended to slow the forward velocity.
>
> A pilot flying a Lanceair IVP with Precise Flgiht found
> himself on short final to the rocks out in California
> a few years ago. Check out the narrative paragraph
> 3 here http://tinyurl.com/m3zxgpw
>
> His deployment of "speed brakes" in fact increased
> his downward velocity. The Precise Flight system
> is not a speed brake.
>
Unfortunately I'm going to have to disagree with Bob here! I'd suggest the term
"speed brake" is quite appropriate when looking at how the Precise Flight system
is designed to work. so it's no surprise that the company have named them
"speed brakes".
Spoilers are designed to reduce lift and moderately increase drag. They do so by
creating a controlled stall over that section of the wing immediately behind
them. Speedbrakes are primarily designed to increase drag with minimal effect
on lift.
On the Boeings and Airbuses I've flown in my day job you'll see the lever which
actuates the spoiler panels labelled "speed brake". On the ground, they function
as lift dumpers. In the air they function as speed brakes. The function is
defined by how many spoiler panels extend and to what degree. On fighter jets
the "speed brake" is normally a pure speed brake - panels extending from the
fuselage and having minimal to no effect on lift.
Going by the photos on their website, the Precise Flight system is narrow perforated
flat plates extending perpendicularly from the wing. I'd suggest this is
a classic speed brake design characteristic, not a spoiler design at all, even
though it's on top of the wing.
The increased drag of speed brakes, or reduced lift/increased drag of spoilers,
can both be used to either increase descent rate or reduce forward speed. The
dominant effect on flight path depends entirely on what the pilot does with the
pitch attitude of the aircraft. It does not necessarily define whether they're
primarily "spoilers" or "speed brakes".
Food for thought. [Wink]
--------
Mike
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=416824#416824
Message 2
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| Subject: | Re: How to Toggle Speed Brakes with Momentary |
On Switch?
On 12/01/2014 10:14 AM, mmayfield wrote:
>
>
> nuckolls.bob(at)aeroelect wrote:
>> Suggest you purge the term "speed brake" from your
>> language used to talk about this system. It's
>> a spoiler system that kills lift . . . designed to
>> INCRASE rate of descent without materially
>> increasing forward velocity. A speed brake puts
>> out DRAG intended to slow the forward velocity.
>>
>> A pilot flying a Lanceair IVP with Precise Flgiht found
>> himself on short final to the rocks out in California
>> a few years ago. Check out the narrative paragraph
>> 3 here http://tinyurl.com/m3zxgpw
>>
>> His deployment of "speed brakes" in fact increased
>> his downward velocity. The Precise Flight system
>> is not a speed brake.
>>
> Unfortunately I'm going to have to disagree with Bob here! I'd suggest the term
"speed brake" is quite appropriate when looking at how the Precise Flight system
is designed to work. so it's no surprise that the company have named them
"speed brakes".
>
> Spoilers are designed to reduce lift and moderately increase drag. They do so
by creating a controlled stall over that section of the wing immediately behind
them. Speedbrakes are primarily designed to increase drag with minimal effect
on lift.
>
> On the Boeings and Airbuses I've flown in my day job you'll see the lever which
actuates the spoiler panels labelled "speed brake". On the ground, they function
as lift dumpers. In the air they function as speed brakes. The function
is defined by how many spoiler panels extend and to what degree. On fighter jets
the "speed brake" is normally a pure speed brake - panels extending from the
fuselage and having minimal to no effect on lift.
>
> Going by the photos on their website, the Precise Flight system is narrow perforated
flat plates extending perpendicularly from the wing. I'd suggest this
is a classic speed brake design characteristic, not a spoiler design at all, even
though it's on top of the wing.
>
> The increased drag of speed brakes, or reduced lift/increased drag of spoilers,
can both be used to either increase descent rate or reduce forward speed. The
dominant effect on flight path depends entirely on what the pilot does with
the pitch attitude of the aircraft. It does not necessarily define whether they're
primarily "spoilers" or "speed brakes".
>
> Food for thought. [Wink]
>
> --------
> Mike
>
But large aircraft do use them differentially for roll control and they
ALL increase stall speeds and sink rates.
Sometime semantic connotations linger. Professional pilots have
inappropriately pulled the handle labeled "speed brakes" while
forgetting about the stall speed increase.
My caution here would be to make sure that the things automatically
retract if the throttle is firewalled regardless of what one calls them.
Ken
do not archive
Message 3
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| Subject: | Re: How to Toggle Speed Brakes with Momentary On |
Switch?
Yes, in the version used in the Legacy they scissor up from the wings - see
image below...
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of mmayfield
Sent: Sunday, January 12, 2014 8:15 AM
Subject: AeroElectric-List: Re: How to Toggle Speed Brakes with Momentary On
Switch?
<mailto:mmayfield@ozemail.com.au> mmayfield@ozemail.com.au>
nuckolls.bob(at)aeroelect wrote:
>
> Suggest you purge the term "speed brake" from your
> language used to talk about this system. It's
> a spoiler system that kills lift . . . designed to
> INCRASE rate of descent without materially
> increasing forward velocity. A speed brake puts
> out DRAG intended to slow the forward velocity.
>
> A pilot flying a Lanceair IVP with Precise Flgiht found
> himself on short final to the rocks out in California
> a few years ago. Check out the narrative paragraph
> 3 here <http://tinyurl.com/m3zxgpw> http://tinyurl.com/m3zxgpw
>
> His deployment of "speed brakes" in fact increased
> his downward velocity. The Precise Flight system
> is not a speed brake.
>
Unfortunately I'm going to have to disagree with Bob here! I'd suggest the
term "speed brake" is quite appropriate when looking at how the Precise
Flight system is designed to work. so it's no surprise that the company have
named them "speed brakes".
Spoilers are designed to reduce lift and moderately increase drag. They do
so by creating a controlled stall over that section of the wing immediately
behind them. Speedbrakes are primarily designed to increase drag with
minimal effect on lift.
On the Boeings and Airbuses I've flown in my day job you'll see the lever
which actuates the spoiler panels labelled "speed brake". On the ground,
they function as lift dumpers. In the air they function as speed brakes. The
function is defined by how many spoiler panels extend and to what degree. On
fighter jets the "speed brake" is normally a pure speed brake - panels
extending from the fuselage and having minimal to no effect on lift.
Going by the photos on their website, the Precise Flight system is narrow
perforated flat plates extending perpendicularly from the wing. I'd suggest
this is a classic speed brake design characteristic, not a spoiler design at
all, even though it's on top of the wing.
The increased drag of speed brakes, or reduced lift/increased drag of
spoilers, can both be used to either increase descent rate or reduce forward
speed. The dominant effect on flight path depends entirely on what the pilot
does with the pitch attitude of the aircraft. It does not necessarily define
whether they're primarily "spoilers" or "speed brakes".
Food for thought. [Wink]
--------
Mike
Read this topic online here:
<http://forums.matronics.com/viewtopic.php?p=416824#416824>
http://forums.matronics.com/viewtopic.php?p=416824#416824
http://www.matronics.com/Navigator?AeroElectric-List
http://www.matronics.com/contribution
Message 4
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| Subject: | Spoilers vs. Speed Brakes |
In my opinion, the Precise Flight speed brakes installed on many
Lancairs, including on my Legacy, are correctly called "speed brakes"
instead of "spoilers."
I think the confusion comes from their installation on the top of the
wings. Obviously, in that position, they do in fact "spoil" lift when
extended. However, a classic spoiler is a narrow panel that extends
across much of the span of the wings. A spoiler's primary purpose is to
kill lift. Here's a photo of a typical airliner spoiler. You can see
that it is much wider than it is tall.
Precise Flight speed brakes, in contrast, extend far higher than would
be appropriate for spoilers and are less than a foot wide; a tiny
fraction of a Lancair's wingspan. As a spoiler, the speed brakes are
terribly designed. Here is a photo of a typical Precise Flight speed
brake. You can see that it is tall and narrow in comparison to a
spoiler.
On Lancairs, which are low drag airplanes, their primary purpose is to
increase drag to slow down. Functioning like flat plate drag devices,
they are dramatically more effective at high speed, when you need them,
than at low speed. That's because drag increases with the square of
airspeed.
The thing that makes this confusing is that they are installed on the
top of the wings, so they also reduce lift. At high airspeed, the drag
effect is much more than the reduction in lift. At low airspeed, when
the drag effect is relatively low, the effect of the loss of lift is
more significant.
If the speed brakes were primarily used for landing, to kill lift like a
glider does, they should accurately be called "spoilers." If they are
used primarily to increase drag to slow down from high speed, then they
should accurately be called "speed brakes." In Lancairs, I don't know
anyone who uses them to kill lift; they're used almost exclusively to
slow down.
Tomato, tomahto,
Dennis
Legacy, 680 hours
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