Frequently Asked Questions - 2010/04

84 MODEL AVIATION
A 14-gram, six-channel-function P-51 Mustang
Bob Aberle | baberle@? Frequently Asked Questions optonline.net
Also included in this column:
• Shock-absorbing landing gear
• Castle Creations ESCs
• TME Xtrema bundle
• Jim O’Reilly plans service
• Follow-up on jet turbine fuel
Martin Newell designed and built this tiny 14-gram, six-channel-function
micro scale P-51 Mustang. It spans less than 10 inches.
Martin Newell adjusts his micro RC P-51 Mustang while
attending the big KIEF in Muncy PA in October of last year.
The underside of Martin’s six-channel P-51 shows the landing gear in
the retracted position. This 1/48-scale model also has operating flaps.
Casey Brandsema modified this aluminum strap-type landing gear so
that it has a shock-absorbing action. This can make for much
smoother landing on rough fields.
PLEASE WRITE IN with your questions;
that is the only way we can keep this column
format going. When referring to published Qs
and As (for follow-ups), provide the number
as a reference.
References to addresses and Web sites are
placed in a group, separate from the text, at
the end of this column under “Sources.”
Q440: “I had heard on several of the RC
forums that a 14 gram scale model of a P-51
Mustang won the Best Micro Aircraft Award
at the Keystone Indoor Electric Fly (KIEF),
held in Muncy, PA this past October. Can you
tell me the details of this model, who
designed it and possibly show a few photos?”
A440:Martin Newell of California, a noted
micro flier, designed and built the winning P-
51. It has a scale of 1/48 and, as you noted,
weighed a total of only 14 grams, or 1/2 ounce.
The model has a wingspan of just 9.25 inches
and a wing area of 14.8 square inches.
Martin custom-made the radio system,
which uses six channel functions. This is what
blows peoples’ minds. Despite the micro size
and weight, this aircraft has aileron, rudder,
elevator, motor throttle, flaps, and retracts.
Think about that for moment.
The power system is a Hextronix 2-gram
brushless motor swinging a 2.5 x 1.0 propeller
running on a single 70 mAh Li-Poly battery
cell.
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Bob’s mock-up of Cas ey ’s landi n g gea r s che m e. You n eed to
s tart w ith a r easonably long gear, since the resu lti ng two pie ces
will o verlap.
TME is selling a bundle deal that includes its Xtrema xG balancing
charger with wattmeter, for a considerable cost savings.
Right: That single beep you’ll hear every 30 seconds or so from
Castle Creations’ Thunderbird-6 brushless motor ESC is a good sign.
One of the pioneers of micro RC flying, Matt Keennon, is a project
manager at AeroVironment. He did the Mustang’s demonstration
flying, to the delight of KIEF spectators.
Martin’s Web site describes the details of this micromodel and has
a YouTube video link that shows how all the controls work. See the
“Sources” list for the Internet address. This little gem even has flashing
wingtip lights.
You can find a detailed report of the 2009 KIEF event in the
November 2009 issue of John Worth’s RC Micro World online
magazine. The Web site is in the “Sources” section.
Q441: “I fly from a very rough field. Hand launching my smaller
models is no problem. But when I have to take off and land on my
field, usually my plane ends up on its back. I suffer structural damage
occasionally, and many broken props.
“I’ve tried various brands of wheels (tires) and that doesn’t seem to
help. Most of my landing gears are the sheet metal type that is often
referred to as a ‘Cessna Landing Gear.’ Is there such an item as a
shock absorber for this type gear?”
A441: You might be surprised to learn that the answer is “yes.” My
fellow SEFLI (Silent Electric Flyers of Long Island) club member,
Casey Brandsema, showed up at our field with a reworked Cessna-type
metal landing gear that includes a shock-absorbing feature.
I’ll describe his basic concept, but you will have to figure out the
details for your particular application. I’ve included a photo that I took
of Casey’s aircraft. Then I made a mock-up so I could include a photo
showing how the gear is fabricated.
The basic idea is to cut off the metal gear at roughly the halfway
point. Then on the lower part, that also has the axle and wheel, cut two
elongated slots. They should be approximately wide enough to
accommodate your choice of 6-32 or 8-32 screws. The larger screws
should be used on the bigger (heavier) aircraft.
Assemble the two pieces of the landing gear with the two screws.
The lower half should then move up or down in the two slots.
The last task is to install an O-ring (as Casey did) or a rubber band,
to keep the lower gear at its maximum extension. When weight is
placed on the wheel, the gear will travel up slightly, absorbing the
landing shock.
I have a series of mock-up photos. If you are interested, drop me an
e-mail and I will gladly attach roughly six pictures in a reply.
That should be most of the details you would need. The only, slight
problem with this scheme is that you do reduce the gear’s overall
length somewhat.
Hopefully your gear is extra long to begin with. If not, you might
have to purchase a longer gear and substitute it for the one your model
has. Let me know how you make out.
Q442: “I own a Castle Creations ESC that controls my brushless
electric motor. After hooking everything up and making sure the motor
ran throughout its full speed range, I heard a single audible beep.
While contemplating what my problem might be, I heard another beep.
“Still pondering a potential problem I heard yet another beep. I
discovered that this beep occurs about every 30 seconds. Like I said
everything works as it should, but can you tell me what the ‘beep’ is
for?”
A442: I recently noted this “beep” on two of my new Castle Creations
ESCs: a Thunderbird-6 and a Phoenix-10. I checked my manual and
found nothing to explain this repetitive sound.
Next I contacted Castle Creations and was told that the beep was
programmed into most (if not all) of the company’s ESCs. Its purpose
is to let you know that everything is working fine—a sort of self-check
of the system.
When you hear the sound at regular intervals, all is well. This alarm
is also handy if you forget, for some reason, to power down your model
after a flight.
If you don’t hear that beep, check to see if you have some kind of
installation or programming problem. So in this case, the “beep” is
good.
Q443: “I recently saw an advertisement for the Tejera Microsystems
Engineering, Inc. (TME) for what appears to be a bundle deal that
includes both their Xtrema xG Balancing Charger and Wattmeter. Can
you shed any light on this offer?”
A443: Albert Tejera of TME has combined two of his products and is
offering them as a package deal at a considerable savings. I’m aware of
both items; they are of excellent quality and are well documented so
that the modeler can put them to the best use. MA’s resident battery
expert, Red Scholefield, has recently reviewed both products, so I
won’t go into it.
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I’ve listed TME’s contact information in
the “Sources” section at the end of this
column. The Web site will allow you to
download the instruction manuals so you can
learn about all of the features and how these
products operate.
Q444: “I’m interested in old-timer and
nostalgia rubber and gas models plans. But I
have to admit that most plan listings by name
alone make it difficult to identify the
particular models. As a result I have bought
plans, only to find out it wasn’t what I
wanted.
“Do you have the same problem?”
A444: I have experienced that problem. Some
plans services include in their listings a
photograph or sketch of the model. I find that
helpful. But in the realm of Old-Timer and
Nostalgia, I did find one plans service that
stands out: Jim O’Reilly Model Plans of
Wichita, Kansas.
Jim is the current president of the Society
of Antique Modelers (SAM). His entire plans
service is done on CADAM.
On Jim’s Web site, listed in the “Sources”
section, you will see the categories of plans
that he sells: “Old Timer Rubber-Powered,”
“Old Timer Gas,” “Nostalgia Gas,”
“Nostalgia Rubber,” “AMA & Misc.,” and
“Scale Models.” If you click on the name of a
model, in blue, it will open to a small
rendition of the plans. This is great for
identification purposes.
The fact that the plans are on CADAM
means that Jim can quickly and easily
print out a set to any size you want. And
he is associated with Bob Holman, who
can make laser-cut parts from any plans.
There is a lot of info on Jim’s site, so
please take a look.
Q423 Follow-Up: In response to this question
and answer, published in the November 2009
MA, I received an interesting note from an
AMA member, Tony Vlasak, who has given
me permission to publish his comments.
He wrote:
“I just wanted to touch base with you
concerning the purchase of jet fuel. The only
restriction I know of, and I’ve been in the
aircraft maintenance business too long, is that
it is not to be purchased for motor vehicle
fuel. First, there are no appropriate taxes on
this fuel and second, I was told by an
associate in the diesel maintenance business
that it does not have the lubricating qualities
and will not develop as much power as diesel
fuel.
“I would caution users not to let it sit
around, as in your response, it will grow
bacteria. This occurs because the boundary
between water molecules and kerosene
molecules is an ideal environment for
certain types of bacterial growth. That
bacterium is extremely corrosive and that
is why jet operators use a product called
Biobore as a fuel additive. It is a derivative
of Borax.
“Aircraft with ‘wet wings’ must have an
additive to prevent this corrosion. Of course,
bladder tanks eliminate this threat however
the growth can still limit fuel flow if the
aircraft isn’t very active.
“Another point of interest came up one
day while I was talking with Mark Frankel.
He had some residue from a filter in his fuel
filter. It was determined that it was probably
residue from filters in the fuel path from the
refinery to the fuel container. Probably from
the last pump, at the airport. This was very
small fibers.
“I hope this clears up some questions.”
Thanks, Tony! MA
Sources:
Martin Newell’s Micro scale RC P-51
Mustang:
http://mnewell.rchomepage.com/Planes/P-
51/P-51.html
RC Micro World
www.cloud9rc.com
Tejera Microsystems Engineering Inc.
11705 Boyette Rd. #418
Riverview FL 33569
www.tmenet.com
Jim O’Reilly Model Plans
(316) 744-0856
www.jimoreillymodelplans.com