REFLECTOR: Glide Ratio and systems knowledge

Sat Dec 17 15:34:01 CST 2005

MessageTerry
Thanks for your input. I'm wondering if there is anyone out there who has shut the engine down ( or of course had an engine failure ) and flown the aircraft to a safe landing? How close is a configuration of idle power to no power at all as far as descent rate and glide ratio go? What happens to the descent rate and glide ratio when you put the gear down? I'd try it myself if I had a 15000' runway available and a lot more hair on my nether region.
Scott............Thanks for the info on the prop control. I had never considered doing that.

Dick
  ----- Original Message ----- 
  From: Terry Miles 
  To: 'Velocity Aircraft Owners and Builders list' 
  Sent: Friday, December 16, 2005 8:57 PM
  Subject: REFLECTOR: Glide Ratio and systems knowledge

  Within the discussion of glide ratio to a landing point, it might be an idea to make each glide excise conclude with a configuration change into a flare target altitude.  It's good also to have a sense of the general window of time/distance/altitude to drop the wheels in a power off glide.   

  Since I get to enjoy a 40 hour fly-off I am going to accept the 90 knots as my target best glide, and practice a lot of power off glides until I can stick the nose right there every time and have VVI and pitch targets too.  I hope to teach myself the pitch corrections of gear down vs gear up.   I don't want to be "inside" a lot if I'm are looking for a landing point.   For me anyway, I plan to keep my auto pilot on the essential power bus, so to ease work load and clear my thinking in times of high demand.    I forced myself to do this as a first step, if I feel I have the flight conditions and reserve battery power to spare.  

  I plan also to do an manual gear extension often enough to know what it sounds and feels like and how long it takes.  This practice will build confidence in it's operation.   (I would not shut off any engines in the name of training.)  

  In my opinion one big benefit to knowing power-off glide dynamics is the ability to make more accurate landing point judgements sooner.  That said, all this is meaningless, if close to the ground, it all goes to hell.  We've all heard it a hundred times, one's best hope of survival is to STAY FOCUSED consciously fly the airplane on speed right down to the flare, with wings level and pointed straight ahead.  .   

  Related topic:  Electrical design is still a work in progress on my airplane, but If I have a load shed routine that removes power from the gear control when it should have the pump maybe, then I'll also make some notes on that abnormal checklist so I won't be surprised when the gear won't go down on the toggle switch.  If I forget to do the load shed, or become too hesitant to change anything, then I may have to compensate when Tower asks that I flash my landing lites and the amp surge blanks-out my PFD screen a few hundred feet in the air.  For me it will take practice to know where to look for that backup airspeed indicator and where to put a hand on that pressure dump valve (and which way it turns!).  

  The above were all equivalent mistakes that I made or watched happen many times over the last 38 years...thank goodness I was in a fancy flight simulator most of the time.  More hours doesn't mean smarter.  I commit to myself every time I strap-in, that we pilots take certain risks.  I am no better than average with a control stick in my hands, but when my time will comes I hope to be practiced and familiar.  I am sorry, I know this is private pilot lesson 101 and we all know it backwards and forwards.  It's just when I hear of preliminary reports like the one this week:  glide distance absolutes...bounced hard...early flares?...airspeed?...fear factors to human performance...I have been taught never to discount any episode no matter how common or bizarre as if there is nothing in it for me personally.   My heart goes out to those guys....grateful they got out OK.  It could have been me.  I'm only a few months away from that point myself.  

  Back to work.

  Terry

   -----Original Message-----
  From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Scott Baker
  Sent: Friday, December 16, 2005 1:39 PM
  To: Velocity Aircraft Owners and Builders list
  Subject: Re: REFLECTOR: Glide Ratio

    Another factor to consider is the pitch setting on aircraft with constant speed propellers.
    With the gear "Up", reduce power to idle and establish a glide speed somewhere near 90 knots (the estimated Best L/D reference speed) - observe the VSI.  Following this pull the propeller control to "Low RPM".  The aircraft literally accelerates as if it were in 'overdrive'.  Re-establish V-best glide and make another note of the VSI.  You should see a 200fpm improvement - or more - in the rate of descent.  Sloooooowly push the propeller pitch control back to the normal position to avoid damaging the engine.
    SB
      ----- Original Message ----- 
      From: Ron Brown 
      To: Velocity Aircraft Owners and Builders list 
      Sent: Friday, December 16, 2005 9:20 AM
      Subject: Re: REFLECTOR: Glide Ratio

      Good Morning Dick,

      I observed 15 and 16 to 1 in my 173 Elite RG at 90 kts.

      It is a fairly easy test to do yourself.

      Fly toward an airport.  At 5 miles from the airport, at say 6000' above the airport elevation.  Get established on your glide speed before the 5 miles to the airport.  Pull the throttle to idle and maintain your glide speed.  When you reach the airport, note your altitude (AGL).  Then calculate the ratio between the distance (5 nautical miles or 6076 feet per mile) divided by the total altitude lost. You can repeat going in the other direction to compensate for the wind.  

      If you want to get brave and pull the mixture to kill the engine, make sure you have enough elevation upon reaching the airport to do a dead stick landing in case you can't get the engine refired.  There is a difference between dead engine and idling, but I didn't try that so I couldn't tell you the difference.

      The Velocity's glide ratio is pretty good - very good compared to a RV or spam can.

      Ronnie

      ----- Original Message ----- 
        From: Richard Affenit 
        To: Velocity Aircraft Owners and Builders list 
        Sent: Thursday, December 15, 2005 11:39 AM
        Subject: REFLECTOR: Glide Ratio

        I remember some conversation about the glide ratio for the XLRG in the past. I wonder if whoever did the testing would mind passing on their findings.

        Thanks...............Dick Affenit N732RA XLRG

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