June Blooms
I just wanted to take a few minutes to send
this e-mail concerning the June cover design. I
have been a member since 1985 and have
received many magazines and this June cover
design has to be one of the best I have ever
seen.
The black and red colors make such great
impressions. Down here in Texas, I would put
it in the same category as running your finger
around the bottom of a freshly baked red
velvet cake with that rich thick white icing
curling up on your finger. Outstanding work!
Thanks to all of you who were involved in
June’s cover design. The magazine is so well
put together and very informative.
Ronnie Barber
Longview, Texas
More Matchmaking
I enjoyed the article by Andy Lennon “Matchmaking” [in the June MA] very much.
It answered many questions I have had about prop sizes.
However, going from a 2-blade to a 3-blade prop requires some guessing, and I was
wondering if Dave Gierke had ever developed a PLF formula for 3-blade props.
Jod Socol
via E-mail
Actually, it’s a matter of gathering data from existing 3-blade propellers and going
from there.
I haven’t had much involvement with 3-blades for quite some time, so I must first
obtain a good cross-section of what’s currently available, and then run them on
representative engines that have known torque and brake horsepower characteristics.
Then, the 3-blade can be directly compared to a 2-blade and its propeller factor
(PF=DxDxP).
Of course, this is all dependent on the design of the 3-blade prop; different
manufacturers will produce a different load on the engine for the same diameter and
pitch. The propeller factor (PF) is really designed to be used within a family of
propellers from a given manufacturer.
So, unfortunately, I can’t provide a brief response that’s meaningful at this time.
I’ve been asked for this by several other individuals, so I guess that I should get
moving.
Dave Gierke
Lancaster, New York
Terrific Rex Review
I just wanted to let you know that I thoroughly enjoyed your article on the 450SE
[“Swash Plate: Align T-Rex 450SE (CDE)” in the June MA]. I was lucky enough to
get one for my birthday (43rd if we’re counting) and it was my first helicopter.
I laughed when I read your comments about the lack of prose in the manual—I
really struggled a bit not knowing
anything about helicopters or
model anything. The slightly
ambiguous diagrams were also
confusing as I wasn’t sure which
way to put the servos, or for that
matter, whether they go on the
inside or outside of the frame. Once
built, it became quite obvious.
I was also completely
intimidated by the sound of the
blades as they roared up to speed,
but thankfully I had been careful enough in the building process that it flew more or
less stable—with any troubles no doubt caused by pilot error.
Aero Mail
Aero Mail continued on page 142
Official Publication of the Academy of Model Aeronautics
SINCE 1936
June 2007 $4.95
Flying indoors at the
Great Planes E-Fest
Your club can have
a blockbuster
model air show
Select the
perfect propeller
for your airplane
August 2007 7
• Displacement: 3.05 ci. (50cc)
• Output: 5 hp.
• Weight: 2.94 lbs. (1.33 kilos)
DA-50 Engine: $595.00
• Displacement: 6.1 ci. (100cc)
• Output: 9.8 hp.
• Weight: 5.8 lbs. (2.63 kilos)
DA-100 Engine: $1,150.00
• Displacement: 9.15 ci. (150cc)
• Output: 16.5 hp.
• Weight: 7.96 lbs. (3.61 kilos)
DA-150 Engine: $1,495.00
[email protected]
www.desertaircraft.com
Phone: 520-722-0607
Fax: 520-722-5622
1815 South Research Loop
Tucson, AZ 85710
DA Engines–
The Choice of
Champions!
DA-50
DA-100
DA-150
08sig1.QXD 6/22/07 11:38 AM Page 7
Edition: Model Aviation - 2007/08
Page Numbers: 7