REFLECTOR: Gliding Distance

Wed Jun 20 10:20:49 CDT 2012

Brett,

I deleted your post, but I want to comment briefly about 110 ias as a down
drift speed.  I will be using something close to that too were I above 5000
AGL, in conjunction with constant awareness of prevailing winds above 20
kts, and being able to pull up NSRT airport info from my GPS without
thinking twice how to do that.   Never mind about triple your altitude minus
field elevation.  Just double it.  If you are 5000 and flying in the
mid-west you can go 10 miles.    I am disinclined to hard formula speak
except for hangar flying and understanding the physics of all this.  That
said if you are trying to hold 85 kts, you will have mushy controls compared
to the normal airloads and control displacements you are used to for normal
in-flight maneuvering.  (Normal in an XL being just above 100 IAS)  

Realize that most pilots will have a tendency not to keep the descent rate
going when the ground starts coming up at them.read: anticipate getting too
slow.   Trim and let go.  It will feel different.  Realize you will likely
want to have a speed pad to execute a flare prior to touch down.  Take your
hand off the throttle, which isn't helping you any, and use it to point at
your airspeed indicator.   Think about how uncomfortable it would be to push
the nose over to get back 5 knots when below 500 feet on final.   All these
things argue for high approach airspeed, confidence in yourself and your
equipment and arm chair procedural training that threads like this should
prompt all of us to be doing.  Payoff is the last 30 seconds-or that last
300 feet-wings level and with energy to swap in the flare.  Have your
passenger prompt you at 5 knots slow.  You guys have been there, and did a
great job, and know about all the sensory overload of this.   

Sorry about the lecture.   Maybe someone picked up a neglected
consideration.  

Terry

Flying Tigers Retired

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of steve korney
Sent: Tuesday, June 19, 2012 7:10 PM
To: Reflector Reflector
Subject: Re: REFLECTOR: Gliding Distance

I think Brooke's  glide ratio is about right for all practical purposes...

Steve 

  _____  

From: bwolf1 at tds.net
Date: Tue, 19 Jun 2012 16:02:27 -0400
To: reflector at tvbf.org
Subject: REFLECTOR: Gliding Distance

You are right Steve.  Thanks.  That would bring my glide ratio to just about
9.5:1.

Brooke

From: steve korney <s_korney at hotmail.com>

Subject: Re: REFLECTOR: Reflector Digest, Vol 87, Issue 104

Date: June 19, 2012 1:55:12 PM EDT

To: Reflector Reflector <reflector at tvbf.org>

Reply-To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>

Yes... 9.5 to 1...... Don't forget that the KIAS is about 12% less then your
true airspeed at 6000ft... KTAS is about 95...

Steve 

  _____  

From: bwolf1 at tds.net
Date: Tue, 19 Jun 2012 13:44:33 -0400
To: reflector at tvbf.org
Subject: Re: REFLECTOR: Reflector Digest, Vol 87, Issue 104

Steve..Just to be clear, do you mean 9.5 to 1, i.e., 9500 feet forward for
every 1000 ft altitude loss?  It looks like mine is nearer 8.5 to 1.
Somehow, somewhere I got the idea it would be 15 to 1!  Maybe that is with a
stopped prop.  

Brooke

From: steve korney <s_korney at hotmail.com>

Subject: Re: REFLECTOR: Gliding Distance

Date: June 19, 2012 1:13:22 PM EDT

To: Reflector Reflector <reflector at tvbf.org>

Reply-To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>

At 85 KIAS @ 6000ft , you have about a 9.5 glide ratio.... What are you
expecting to see....?

Steve 

> From: bwolf1 at tds.net
> Date: Tue, 19 Jun 2012 12:26:23 -0400
> To: reflector at tvbf.org
> Subject: REFLECTOR: Gliding Distance
> 
> I am planning some overwater trips in the near future and the subject of
gliding distance naturally comes to mind. I have done some limited test
flying with my airplane (XLRG w/Aerocomposite variable pitch prop). The
results of my gliding performance are not too good. All tests were done
around 6000ft with throttle at idle and wheels up. Here are the results:
> 
> 80 KIAS - 900fpm.... yields a glide performance of 1.38 miles/1000 ft
altitude
> 85 KIAS - 1000fpm....yeilds a glide performance of 1.41 miles/1000 ft
altitude
> 100 KIAS - 1250fpm ...yields a glide performance of 1.34 miles/1000 ft
altitude
> 
> As you can see, 85 KIAS appears to be the best glide speed.
> 
> I know there may be a big difference in what I tested and what happens in
the real world with a windmilling or stopped prop. Have any of you brave
test pilots done any testing with a windmilling or stopped prop? What were
the results? What kind of glide performance did others get with throttle at
idle? Is there anyway to correlate throttle idle glide performance with
windmilling or prop stopped performance? What is the best way to stretch a
wheels up glide on a Velocity?
> 
> I would like to get a discussion going on this and find what others have
experienced. Thanks.
> 
> Brooke, N108BG, XLRG-5, 145 hours
> 
> 

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