Increasing duration in F1D - prop settings and back-off

From: Tapio Linkosalo <tapio.linkosalo_at_iki.fi>
Date: Wed, 14 Mar 2012 07:54:09 +0200

Last night when making motors (for F1B...) my thoughts turned to
Belgrade, again. Started to wonder what to do to climb up the ladder of
duration (I'm currently at 26 mins, so next target should be closer to
30...)

Comparing my flight profile to the one that John was flying in 2010, I
was surprised to see him taking almost 20 minutes to climb to the
ceiling. My model was at the apex of the flight profile in 10 mins... So
obviously this is where the missing flight time lures. One thing that I
need to fix for next summer is to modify my VP's to take higher max
pitch, currently I'm against the top stop (cannot adjust any further),
and need to take backoff to avoid hitting the ceiling.

So this is the first question: should I aim to fly with no backoff at
all, and just add the max pitch to control the amount of the climb?

Second, my props use a "soft" spring with multiple turns. Thanks to very
informative discussion with the Brits last summer, I now understand that
this kind of spring works with a rapid movement from high pitch to low,
and indeed this was showing in my flight profile last summer: after the
apex at 10 mins, the model started descending, until at around 14 mins
the pitch changed, resulting in a shallow second climb and then cruising
down for the rest of the flight. Maybe a "harder" spring of fewer turns
would enable similar action as Treger was showing, with a long cruise
not changing much altitude throughout the middle parts of the flight? I
suppose this would, however, make the adjustment of the spring
pre-tension much more sensitive than with a softer spring?



-Tapio-
Received on Tue Mar 13 2012 - 22:54:16 CET