REFLECTOR: Glide Ratio for the math challenged

[Reiff Lorenz]

Larry,

Great tip! I remember my flight instructor pointing out that 1000 ft/min = ~10 knots. It had not occurred to me that this could be divided into IAS to compute approximate descent ratios.

Of course, there is always the option of forgetting all the math and just installing Vertical Power's VP-400 engine-out-autopilot. Who needs piloting skills when there's technology to save us?!?

Reiff Lorenz, Dayton, OH
Velocity XL-RG, 33% complete
Currently working on: Assembling Harbor Freight engine crane
Half the work of building an airplane is building the stuff that builds the airplane!






From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Laurence Coen
Sent: Thursday, June 21, 2012 2:30 PM
To: reflector16
Subject: REFLECTOR: Glide Ratio for the math challenged

As has been pointed out, you must use the same units of measure for both horizontal and vertical speed.  Since the VSI is reading feet/min and 1 knot is about 100 feet/min you need only multiply knots by 100 and divide by the vertical speed.  Thus a VSI of 1000 and 85 knots is 8500/1000=8.5 .  Simple and easy to remember.  Before someone points out that true airspeed will be greater that indicated I'll point out that it is better to be able to glide further that you calculated than less.  When the fan stops, establishing ideal glide speed, deciding where to land, wind and maneuvering are all bigger factors in a happy outcome.

Larry Coen
N136LC
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