CHAPTER IX - Anchor & tie down
I 've noticed that pilots & airfield supporting personel, use a number of improvised anchors types, to tie down the gliders, ultralights or even single engine aircrafts such as Cessna 172s, especially when operating from some grass covered airfield, without any permanent anchorage points & lashing hoops installation on ground. These improvised anchors are made of concrete filled tires or cement block bricks also known as
CMU - Concrete Masonry Units).
The tying is part of the checklist and therefore gliders, ultralights, gyrocopters etc, should remain tied and with wheel chocks instaled when grounded, because even the slightest breeze can cause to aircraft start rolling or flip the wings and hit wingtips on ground or worst. I've watched a video on YouTube, where a RAF's BAe Harrier GR.7 aircraft with no wheel chocks installed, began trundling because the wind gust, gone away from the apron and finally stopped on the grass, several meters away from the initial parking position. During this special "ride", the ground personnel just stood and watched the embarrassing view. Fortunately, no big damage caused that day, if we exclude some taxiway sign & the fence fell down and of course the groundcrew chief's pride. So, if this can happen on a mighty fighter jet that weighs 13 tons, why not also happen on a glider or an ultralight?
Building this improvised anchor made by concrete filled tire under scale, seemed OK to me. My first thought was to 3D print it and for this reason I actually, had just the right CAD model waiting for this purpose, in my laptop’s HD. Not having anything more to do that afternoon, I took my Mrs for a ride in town and some shopping at local Mall.
As people say, everything starts with a wish. And then, just like that, while shopping at the supermarket, I found the following item (actually a pencil eraser set for kids), for 0.5 € only. Sometimes the simplest idea can make the biggest difference and it looks like someone had the idea to produce & sell some pencil erasers that look like car wheels, waiting for me to find it, when I need it. Since I found this item which looks like a weathered wheel tire and seems to meets the criteria for 1/18 scale size, for a
cheaper than dirt cost, I had no reason to 3D print the tire.
PS. Damn’d, I should wish for “
World Peace” instead of “
I need a 1/18 scale tire”.
I removed the rim and filled the inside of the wheel with plaster to recreate as closely as I could the rough surface of cast cement & gravels. Because the plaster mixture was quite watery, I had plenty of time until become hard. So I also added some grains of volcanic sand into the plaster mix, hoping to recreate gravels. These volcanic sand grains (hand picked during summer vacations at the island of Santorini) seem to be ideal for the purpose and weight much less than normal beach sand.
As soon as the plaster cast got harden, the anchor was sprayed over with Humbrol light grey acrylic primer to get prepared for the FS 37038 "
Matt Black" available by Life Color as LC02 acrylic. Later, the gravels were also painted with light gray & sand shades.
The paint allowed to dry for a couple of hours before starting the dusting process. The next two steps involve the use of pigments, which would give visual interest on the old & weathered tire. To get best results, I used "
Raw Umber" pigment, a small metal cup, a flat brush and a bit of water. I add some grams of pigment powder and few drops of water into the cup to make the right mixture. It is important to add a tiny amount of water in order to make the mixture look like mud - not like soup. For this reason, I use a syringe to add just few drops on the pigment powder and I stir using the brush. The pigment applied with paintbrush with pressure, over the whole surface.
When the pigment wash dried, I rubbed off the high spots with a hard toothbrush and removed the dust excess. The high spots were cleaned to the basic finish and the low spots were left dusty. As soon as it looked OK to me after brushing & removing "
Raw Umber" pigment dust, I continue to second step and add some grams of White pigment powder in the metal cup. Using a flat brush, I tried a pigment powder drybrushing, on the areas that supposed to be more enlighted.
Afterwards, the surface was soaked with fixative by Winsor & Newton, to fix the previously applied pigments, moving in a motion outwards the center of the wheel. As a final touch, I tried some drybrushing on gravels, using light gray & sand acrylic paint.
