Since
my airplane power system used a 10-cell Lithium pack, I choose
the 50v audio amplifier so I could connect it right to the ESC
power lines. The engine sound control is either connected in-line
to the throttle channel or to a spare channel for additional scale
control. I needed to make my own cable, with female servo connectors
on both ends, to connect the second channel control to my receiver
for the machine gun sound. The photo above shows only one speaker
for my initial testing setup. I later added the second speaker
in series as shown below.
I
managed to stuff the metal frames of the two 4" speakers
in the small scale nose of my P-51D. A small portion of the frame
protruded from the bottom of the cowl. I used a Dremel tool to
cut the fiberglass cowl.
The
Aerosound 4 speaker is custom manufactured for Aerosound
with selected components and a powerful neodymium magnet to be
as light weight as possible yet deliver the best possible sound
at high decibel levels. They measure 4 in diameter by 1.69
deep and weigh 6.6oz. each. The sound level produced on my setup
is about 98dba. Up to 102dba has been achieved using two 16oz
speakers.
Since
the contacts to initiate "Learn Mode" are very tiny
and require a small pliers to activate, I added my own pushbutton
to easily activate the Learn Mode for fine tuning my throttle
control points once the system was installed in the plane. The
tiny TBS Micro Soundmodule was not easy to solder the wires onto
for my added pushbutton.
After
the first test flight, I later drilled many small holes in the
cowl to help aid the sound volume.
We
flew the P-51D with the Aerosound module at a local electric R/C
show. It sounded great and the audience really loved the added
scale effect of hearing a Merlin V12 in an electric conversion.
The video below shows the realistic scale sounds with the various
sequences like starting, engine idle, acceleration, returning
to idle and engine shut down.
Aerosound
P-51D Video (17meg)
Summary
The
overall performance of the sound coming from the P-51 approaches
realism and gives a great scale effect to the model. I think this
product will add a new dimension to electric flight...especially
competitive scale applications. Although you cannot create your
own sounds, you can reprogram them into the TBS Micro Soundmodule
and there are many real recordings to choose from at Aerosound
RC. The whole sound system draws less than 4 amps with both
speakers connected so it does not adversely affect the flight
time.
I am happy with the current sound level in my P-51 and I saw no
evidence of interference from the added circuitry. The sound level
is close to scale but I am considering several other improvements
for next season. One is to replace the small drilled speaker holes
with a single large opening and cover it with cloth. Another is
to replace the medium end 4" speakers with more expensive
versions that have larger magnets and can handle more power. The
50v amplifier has a volume adjustment on it and is not running
anywhere near the maximum level for the 4" speakers. The
amplifier can easily overdrive the 4" speakers so care must
be taken when adjusting the volume level.
I
simply did not have the freedom to create speaker boxes in my
P-51 model due to the limited space. The main purpose for a speaker
box is to increase sound level. This comes at the cost of some
weight and additional space. Other models like the P-47 have a
much larger fuselage than the P-51 so they can make use of techniques
like a speaker box or larger speakers.
The
Benedini sound system made my P-51 sound like a real aircraft.
Many of us have been waiting a long time for this technology to
make it into the R/C market. That time has arrived and it is exciting
to be a part of it!
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