REFLECTOR: Takeoff roll - fuel burn

Al Gietzen ALVentures at cox.net
Fri May 22 11:54:46 CDT 2009


A further comment - For me and my plane the limiting factor is landing
distance, not takeoff roll. While doing these tests I found I had to brake
fairly hard to make the exit at 2400'.  Rolling out over the numbers I still
carry quite a way in ground effect before the mains touch.

 

Al

 

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Al Gietzen
Sent: Thursday, May 21, 2009 10:47 PM
To: reflector
Subject: REFLECTOR: Takeoff roll - fuel burn

 

Here's a bit of data from today's measurements.

The question came up here awhile back about fuel economy vs CG.  I did
flights today in my SE RG with CG at 120", total weight about 2060; and at
116", total weight about 2270.  The CG was shifted by adding a person in the
right seat. Surprising; within the accuracy of the measurements, both cases
were the same: 160 KTAS burning 9.5 gph at 2500 rpm on a fixed pitch prop
(rotary 20B, lean cruise). At pattern speed of about 100 KIAS I noted the
heavier, forward CG took more power; but I didn't take any data.

 

Takeoff roll - 85F; 1400' field elevation, roughly 8-10kt wind component
down the runway, fixed pitch cruise prop.

 

Weight - 2100; CG - 120"; about 1630 ft

Weight - 2300; CG - 120"; about 1730 ft

Weight - 2300; CG - 116"; about 2300 ft

 

These are all single run measurements, taken by spotting relative to taxiway
exits and edge lights, and taken from a rolling start - rolling on to the
runway, getting it straight and adding power. Moving the CG forward made a
more dramatic difference than adding weight, and I didn't like the way it
handled at pattern speed, or landing.

 

The first case above was repeated using so-called 'Short field takeoff'
procedure - getting lined up near the end of the runway, and applying power
while holding brakes; then release.  Takeoff roll was the same as the
rolling start. My rotary spools up very quickly when I push in the throttle;
things may be a bit different with a Lyc.

 

Al

 

 

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