REFLECTOR: Speed Brake

Wed Jul 14 15:19:49 CDT 2004

This thread reminds me of some "philosophical" decision I had to make in
planning the systems for my plane.

As a self-confessed gadget freak, I put my fair share of technology into
my cockpit.  A lot of the systems have fairly high levels of integration
where information from many source are aggregated, tracked and presented
in a form that is meant to reduce confusion and error.

Where I drew the line was "who pushes the button".  In other words, none
of the gadgets in my airplane ultimately "push the button" for me.
Throttle, mixture, prop pitch, flight controls, radio switching,
external and internal lighting, fuel pump, speed brake, pitch trim, etc.
The gadgets give me the data but I am still in the loop to make the
decision to make the plane do what I think needs to be done.  I have
considered putting in systems like automated pitot and carb heat, fuel
pump control, etc but decided against it.

I think the similar philosophical difference can be seen between Boeing
and Airbus designs.  Boeing takes the approach where it leaves the
ultimate decision making to the pilots who flies the plane where Airbus
can override the pilot actions and does what the airplane thinks is
right.  You might have seen a video of an Airbus plowing into the woods
in landing attitude.  It happened at an airshow where the pilot intended
to do a low and slow fly-over and go around.  The plane insisted on
continuing landing into the bush.

I worked in the technology industry long enough not to trust it with the
final decision<g>.

Hiroo

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Scott Derrick
Sent: Wednesday, July 14, 2004 12:25 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Speed Brake

Sometimes making things automatic can bite you in the ass more easily
than 
they can help you.

I think this is one of them.   I would not want the speed brake to 
automatically deploy or retract on me.

Scott

At 10:56 AM 7/14/2004, you wrote:
>xmlns="http://www.w3.org/TR/REC-html40" xmlns:o = 
>"urn:schemas-microsoft-com:office:office" xmlns:w = 
>"urn:schemas-microsoft-com:office:word">
>Good suggestion, Christopher.  Your comments made me consider how to
take 
>it past the an alarm and to automate the retraction under this set of 
>conditions.  Routing the input that would be used for an alarm (i.e.. 
>micro switch, hall effect, or prox sensor on the throttle linkage) to a

>DPDT relay could facilitate both an alarm and an automatic retraction
of 
>the speed brake.  1 of the DPDT poles would be used to trigger the
alarm, 
>the COM contact of the second pole is connected to the CB for the speed

>brake, the NC relay contact is connected to the COM of the speed brake 
>switch, and the NO contact to the retract side of the speed brake 
>actuator.  When no alarm condition exists the speed brake switch will 
>control normally, if the alarm/relay is triggered the actuator is
powered 
>to retract and when retracted the internal switch turns power off to
the 
>motor.  When the throttle is retarded out of the alarm range, the speed

>brake switch regains functionality.
>
>I hope I remember this when I start wiring my AC.
>
>Joe
>----- Original Message -----
>From: <mailto:christophercmartin at earthlink.net>Christopher Martin
>To: <mailto:reflector at tvbf.org>Velocity Aircraft Owners and Builders
list 
>; <mailto:reflector at tvbf.org>Velocity Aircraft Owners and Builders list
>Sent: Wednesday, July 14, 2004 12:20 PM
>Subject: Re: REFLECTOR: Speed Brake
>
>I have watched this conversation with real interest and having flown my
XL 
>RG almost 500 hours without one, I find myself very interested in the 
>potential for rapid decent to the airport without shock cooling the big

>IO-540. The description posted of staying up at altitude and making a 
>rapid decent with the speed brake is a real advantage. Normally that
sort 
>of procedure requires such a reduction in manifold pressure that you
would 
>shock cool the engine badly. Probably in the area of 80 degrees F per 
>minute. Far beyond the normal factory limit of 50 and the preferred
user 
>applied limit of 35. So, I find myself very interested in retrofitting
the 
>speed brake into the plane. There is however, one little caveat that I 
>have not heard anyone mention and that is the control system necessary
to 
>avoid "go arounds" or "touch and gos" with the speed brake deployed.
>
>I remember coming into Santa Monica airport on a July afternoon three 
>years ago and finding aircraft parts scattered all over and three
parked 
>planes banged up. A fellow velocity pilot had crashed and, fortunately,
he 
>and his wife walked away unscathed. His plane and three other planes
were 
>the only causalities. His problem had been the deployed speed brake. He

>was coming into a normal landing with a crosswind approach with speed 
>brake deployed. Just as he touched down he encountered wind shear and
so, 
>attempted to do a go around. He powered up and tried to take off but
with 
>his speed brake deployed and the shifting wind he was unable to gain 
>altitude. He took out three parked airplanes in the process. His later 
>remark was ,"if only I had remembered to retract the speed brake". So,
in 
>my desire to now retrofit a speed brake into my ship. I need to also 
>install an alarm that enunciates if the speed brake is deployed and the

>throttle is increased. Not to difficult to! do but a necessary addition
in MHO.
>
>Chris
>
>Christopher Martin
><mailto:christophercmartin at earthlink.net>christophercmartin at earthlink.n
et
>
>
>
>----- Original Message -----
>From: <mailto:gpoole at zeta.org.au>Greg Poole
>To: <mailto:reflector at tvbf.org>Velocity Aircraft Owners and Builders
list
>Sent: 7/15/2004 1:48:25 AM
>Subject: Re: REFLECTOR: Speed Brake
>
>Thanks for your sentiments Randy,
>
>Strange thing.....I find many aviators tend to express opinions to back

>their own MO of having or not having a speed brake on their airplanes
and 
>one is left in the middle quite confused.
>
>I don't particularly want to influence you one way or the other and
have a 
>speed brake just for it's insurance value - both to protect whatever 
>constant speed prop I end up putting on, and to get down in a hurry if 
>ever I need to. I also like the idea of having such a gizmo to activate
on 
>my aeroplane.
>
>...if ever you and Bec make it down this way - look us up!
>
>Kind regards,
>
>Greg. (DownUnder)
>Greg Poole
>[]
>
>Principal POOLED RESOURCES PTY LTD
>3 Cheltenham Close
>Castle Hill NSW 2154
><mailto:gregpoole at pacific.net.au>gregpoole at pacific.net.au
>tel:
>fax:
>mobile: (612) 9899 2737
>(612) 9899 2726
>0414 273199
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>----- Original Message -----
>From: <mailto:rwharton at buckeye-express.com>Randy Wharton
>To: <mailto:reflector at awpi.com>reflector at awpi.com
>Sent: Sunday, July 11, 2004 3:05 AM
>Subject: REFLECTOR: Speed Brake
>
>I'm new to the Reflector, so I hope this works!
>
>
>
>I have an XL-RG and I'm curious about the speed brake. It's marked on
the 
>fuselage as "optional", and there is nothing in my manual about it. I 
>checked out the online manuals and found that the speed brake is only 
>addressed in the fixed gear models. I know that with retractable gear,
the 
>gear down will act as a brake to some extent, but does anyone know of a

>compelling reason why I should or should not install the speed brake?
>
>
>
>Randy and Becky Wharton
>
>N248RB - Velocity XL-RG
>
>http://clik.to/velocity
>
>
>
>
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"Those who sacrifice freedom to get security, deserve neither."
- Benjamin Franklin

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