Re: Re: Coconut Scale [1 Attachment]
Thats Jeff Hood with the Dronier
--- On Fri, 2/15/13, Stew Meyers <stew.meyers_at_verizon.net> wrote:
From: Stew Meyers <stew.meyers_at_verizon.net>
Subject: Re: [Indoor_Construction] Re: Coconut Scale [1 Attachment]
To: Indoor_Construction_at_yahoogroups.com
Cc: joshuawfinn_at_gmail.com
Date: Friday, February 15, 2013, 10:01 PM
[Attachment(s) from Stew Meyers included below]
The word should have been Minimum span.
See the attache picture of the first Coconut contest at Pax river.
Six modelers entered the first COCONUT contest at Pax River; Don
Srull with an Alco Sport, Bud with his Spirit, Pat Daily with a
Curtiss Robin, cannot remember this modeler with the Dornier, Dave
Rees with a Waco, and Tom with a Lincoln AP.
THE COCONUT SPIRIT
Bud Carson
The interest generated by my 36" indoor scale Spirit of St. Louis
at the November Pax River gala came as a pleasant surprise and I
was quite pleased at all favorable comments it got. The model was
designed for the sheer fun of it, and to this extent it was
certainly successful, completing several dozen flawless flights to
the delight of the crowd and the relief of the author, suffering
nary a scratch or a blown motor. The idea came when I contemplated
that magnificent flying site something was needed that would fill
up the room but do it in a survivable way.
Thus-the Spirit was reincarnated in indoor trappings. As such it
won't stand up to the rigors of outdoor flying, but on the hand,
has proved remarkably resilient to the inevitable wall and rafter
bashes that so often spell disaster to typical outdoor models when
flown between four walls. During the initial trimming flights and
before the correct amount of rudder offset was established (which
proved in the end to be far more than I would have thought
necessary) the Spirit had its share of heart stopping encounters
with the local terrain with nothing more than a split prop blade
to show for it, proving once again that low inertia indoor model
"crashes" tend to be rather leisurely affairs.
I hope this example will encourage others to follow suit with
their own versions, even though there are no official events for
this class. In case there ever is, I have labeled this category
"coconut scale" in keeping with the familiar peanut and walnut
scale categories, the coconut being the biggest nut of all, yours
truly excepted. To help things along, I have put down some
thoughts, realizing that the formidable Maxecuters are superb
modelers and need no instruction on basic technique.
1. For a first attempt, stick with the tried and true. I suggest a
high-wing, externally braced configuration. Feel free to tinker
with landing gear length, tail surface areas, and dihedral (all of
which is allowed by FAC rules, incidentally) and make a working
sketch or drawing before plunging into the actual construction.
2. Use Yoga, TM, or whatever suits to get yourself into an indoor
mind set. Lightness not only spells endurance, it is the key to
survivability; heavy models hit harder, and vice-versa. Select
wood carefully for strength and lightness, and resist the urge
(which can be quite overpowering at times) to add unnecessary
structure. Don't get caught in the weight-growth tangle. When in
doubt, scrimp, obeying the aeronautical engineer's credo:
simplify, and add lightness. Be especially careful about tail
weight, which can be a real killer. A needless gram in the tail
may easily require three more in the nose, to balance it, wiping
out as lot of the "lightness'' that you have carefully "added"
in-the rest of the structure.
Remember that conventional models seem to have a lot of
unproductive structure devoted to no other than to prevent warps,
collapsed wing ribs, etc. caused by tissue tension. Since you
won't be shrinking the tissue on flight surfaces, they can be made
lighter than you are used to. The wings on the Spirit had only
twelve 1/32" ribs and the trailing edge was 1/16" square.
3. Take full advantage of any bracing that appears on the
prototype. The wings on the Spirit were very tender when framed up
and downright floppy when covered, which meant that they were
about right. When the struts were added, the wings became stiff
enough to take the flight loads, but still retained enough
resilience to survive a cartwheel without damage (try that with
your 15 lb. RC scale job !)
4. Fashion bulky items such as wheels, dummy engines, nose blocks,
etc. from foam. This not only saves weight but lowers their
inertia so they remain attached during close encounters with
immoveable objects. If the airplane is very light and the wheels
are too, the whole landing gear assembly can be glued on to the
lower longerons without benefit of weight-enhancing piano wire
reinforcements. Coat wheels, etc. with Elmer's or Titebond to give
them dent resistance, strength, and a good base for sanding and
finishing.
5. As for covering and finishing: all flight surfaces on the
Spirit were single-covered with white paper that had been
presprayed with silver Rustoleum. The celebrated N-C-211
registration number was applied to the paper prior to covering
using a large stencil coated with spray adesive, and sprayed
black. The fuselage was covered and shrunk conventionally, and
later sprayed directly without benefit of clear dope. As a result,
I don't think there is more than a gram of paint on this model,
which grossed out at just under 30 grams. Of course, tissue, magic
markers, etc. can all be used, depending on the model. A light
coat of clear acrylic on the raw paper will retard shrinkage and
subsequent warping of the flying surfaces as humidity varies over
time.
6. After much agonizing, I finally decided to attach the wings on
the Spirit permanently since there seemed to be no way of
maintaining rigidity with a detachable wing. This has worked out
well, and losing trim each time the wing is removed is of no
concern.
On 2/15/2013 3:51 PM, joshuawfinn_at_gmail.com wrote:
> Where do we stand on this?
I've got a good set of rules ready to go.
> Joshua, can you describe the inaccuracies of the
recent rules?
Yup...have a look at what I'm about to do:
> 1. Recognizable rubber powered scale model, with a
max. 36-in wingspan for a monoplane, 30-in wingspan for
multi wing.
That's a problem: "with a max. ...". That is not correct,
especially since I have never seen a monoplane coconut
with a wingspan under 36", and Aronstein's was very nearly
twice that.
So the mere fact that we have for quite a while been
sending out a set of rules for Coconut that have an error
in the very thing that defines a Coconut as such makes me
a bit concerned.
The corrected rules are to be sent out with the FAC stuff
since we're only doing the mass launch this time.
Good flying,
Joshua Finn
Received on Fri Feb 15 2013 - 14:23:44 CET
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