Design: Dihedral Recommendation

[Ted Sander]

Matt -
Yep, my thoughts exactly - This project all came about because last summer
a) I crashed my Calypso (yeah, "old fashioned", but a heck of a aerobatic
plane), and b) out of how much I've learned to dislike my H9 ARF CAP.  That
one I had to add 1 lb of dead batteries to the nose.  I'm making sure the
new one will work out correctly!  Fine for a Sunday sport flyer, horrible
for anything precision.  BTW - I'm using an FPE 2.4 gasser, which replaced
the YS 1.20 it used to have.  After pipes, alum. hard mounts, etc. were
removed and replaced - the all up weight was the same - 48 oz of stuff for
each engine.  Doesn't count the ignition batteries..but I needed nose weight
anyway!  That's why the hopes I can campaign with this as a dual purpose
plane - Pattern and IMAC.  Should be able to hit the 11lbs, if I'm really,
really careful.

-----Original Message-----
From: Rcmaster199 at aol.com [mailto:Rcmaster199 at aol.com]
Sent: Sunday, May 11, 2003 10:52 AM
To: tedsander at attbi.com
Subject: Re: Design: Dihedral Recommendation

In a message dated 5/10/2003 11:54:08 PM Eastern Daylight Time,
tedsander at attbi.com writes:




Subj:RE: Design: Dihedral Recommendation
Date:5/10/2003 11:54:08 PM Eastern Daylight Time
From: tedsander at attbi.com <mailto:tedsander at attbi.com>
Reply-to: discussion at nsrca.org <mailto:discussion at nsrca.org>
To: discussion at nsrca.org <mailto:discussion at nsrca.org>
Sent from the Internet



Thanks George - FYI, I'm anticipating ending up with about 3.5 degrees of
right thrust.  I'll start with 3, and adjust from there.  Down will start at
zero, and be set as flight testing dictates.  Gas engine, big prop (20x10).
Vert. Stab/Rudder will be counterbalanced.  Planform isn't too far different
than on a Focus.


Ted,

You want a small amount of downthrust if you want the model to track true
vertical up lines. For this size model, about 11/2 to 2 degrees down is a
good place to start. If the model is going to be used mostly as a fun flyer,
different story. It matters alot less.

Your right thrust is also about right for the large gassie

One other consideration is wing placement. The gassie is heavier than
alkies, so you should probably start with a foreward wing location, to keep
the CG from needing too much tail weight, even if you are planning to use
elevator servos in the tail. At least 1" further forward to start. If you do
move the wing, then the down and right thrusts become more important. Think
shorter moment

Matt K
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