REFLECTOR: Speed Brake

Wed Jul 14 11:56:56 CDT 2004

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: Christopher Martin 
  To: Velocity Aircraft Owners and Builders list ; 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
  christophercmartin at earthlink.net

    ----- Original Message ----- 
    From: Greg Poole 
    To: 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  
                            gregpoole at pacific.net.au  tel: 
                                fax: 
                                mobile:  (612) 9899 2737
                                (612) 9899 2726
                                0414 273199  

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      ----- Original Message ----- 
      From: Randy Wharton 
      To: 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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