Page 4 - EAA78.Newsletter.Archives.(February.2017-July.2021)

Experimental Aircraft Association June, 2021
Delaware Valley, Pennsylvania Volume 45, Number 6
Doylestown Airport (KDYL)
3879 Old Easton Rd.
Doylestown, PA 18902
Meets: Last Wed each of month (7:30 PM)

CHAPTER CHATTER

Chapter Number 78 Flying Through History

3 Rules-Of-Thumb For Flying In Hot
Weather:

When the weather gets hot, these rules-of-thumb can
help.

1) The 50/70 Rule

The 50/70 rule is a general rule for GA aircraft
that says if you haven't reached 70% of your
To use the rule, first, calculate 70% of your
takeoff speed by the time you've reached 50%
takeoff speed. Second, find a visual point
of the length of the runway, you should abort that's 50% down the runway. If you've reached
your 70% speed before you've reached the
your takeoff.
visual point 50% down the runway, continue. If

Why do you need 70% of your takeoff speed not, abort.
by 50% of the runway? As you accelerate

down the runway during takeoff, you start
chewing up more feet of runway for every

second you're rolling down the pavement. If

you haven't achieved 70% of your takeoff
speed by the time you're halfway down the

runway, you may not have enough pavement

left to get to rotation speed and lift off.

2) Takeoff roll increases about 10% for every
additional 1,000 feet of density altitude

For most normally-aspirated GA airplanes,

you'll add about 10% of takeoff roll for every
CONTINUE
1,000' of DA.