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
>
>
- application/x-ygp-stripped attachment: stored
Received on Fri Feb 15 2013 - 14:01:34 CET