RE: Light-Sport Aircraft Yahoo group Aircraft Payloads for comparison.

Well…in theory (and practice) you should do a  weight and balance computation every time so the answer would right there.  For example, pilot weight can change up or down 10 pounds or more depending on the contents of the flight bag, heavy clothes, camera..etc…not to mention that big breakfast you had before flying…lol

 

But that being said, the computation is simple enough,….Gross weight – empty weight –((gph * 2.5)*6) = payload.  One of the reasons it is difficult to stick a number for fuel burn for 1 hour of lesson with a 1.5 hour reserve is the training environment changes demands on fuel flow depending on what training is being done, how much time is spent on the ground waiting for ATC clearance to taxi, take-off and climb out instructions, etc.  With most of the new aircraft (Rotax engines), fuel leaning is not an issue, but if you are doing your training in an aircraft with a mixture control, fuel burn can vary pretty wildly depending on how you lean.   Altitude makes a huge difference on fuel burn.  Whether you cruise at 65% or 75% power is another factor.

 

So, for a manufacturer to make an assumption considering all these variables, well…that would be a leap of faith.  However, for a personally owned general purpose fun/travel plane, you would probably have a good “round figure” in your head that you can use.  For example, at my takeoff altitude and the altitudes I normally fly at, my Cherokee burns around 8gph.  The book says 8.5, but experience tells me 8.  So what do I do?  I use 9 as my preflight planning number.  A full tank is 50 gallons and to the tabs gives me 36…plus or minus depending on human error, so I have either 4 hours or 5.5 of duration depending on where I filled the tanks to.  Full tanks, compared to tabbed tanks, give me 84 pounds less payload and since I’m very seldom at gross weight when I fly, I like full tanks for a cross country.

 

From: Sport_Aircraft@yahoogroups.com [mailto:Sport_Aircraft@yahoogroups.com] On Behalf Of Ed Burkhead
Sent: Monday, November 14, 2011 4:07 PM
To: Sport_Aircraft@yahoogroups.com
Subject: RE: Light-Sport Aircraft Yahoo group Aircraft Payloads for comparison.

 

 

 

For a training aircraft, I’d like to see all these numbers recomputed based on a 1-hour lesson and 1.5 hours of reserve.

 

In that condition, what is the useful load?

 

That, to me, is a MUCH more useful number for a trainer.

 

For a personally owned general purpose fun/travel plane, I’d want to know both that number and the full-fuel payload numbers.

 

Ed Burkhead

http://edburkhead.com/Ercoupe/index.htm

ed -at- edbur???khead (dot) com        (You can fix it up, as needed)

 

Strongly recommended e-books (virtually all formats):

The Warrior’s Apprentice*  (novel)               * good starting points for the series

The Mountains of Mourning*  (novella)

all by Lois McMaster Bujold (my favorite author)

available legally, for free, from the publisher

(to tempt you into buying the rest of the author's books)

http://www.webscription.net/c-1-free-library.aspx?SectionFilterID=13

 (And yes, this is a safe site.  For those who want extra safety, Google the word “Webscription” and visit the site via the links you find that way.  Ed)

 

The Baen Books free library - all authors:

http://www.webscription.net/c-1-free-library.aspx

(ditto)

 

(Just supporting good authors – it's sometimes hard for even established authors to get “found” by new readers these days.)

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