This site will be under construction forever, but for now I
will present the following tips...
- 35mm film cans make nice hobby-size containers for
holding many different items used in model making. I mix
my balsa filler (Finishing Wood Filler) with a little
water into a film can so that it is a good consistancy
for painting on. Stays good for a long time. And the best
part of this tip...if you save the lids from cans of
spray paint, you can slip the film can right into the
spray paint cap and it makes a really stable base for the
film can and gives you some side compartments for clear
water or just a place to stick the brush. The system
worked good when I was doping and painting my tissue
covered plane. I had 4 or 5 of them going and besides
having the clear bottles (film cans) I had color coded
'bases' (different color paint tops). Sure makes them
stable and the film can seems to fit in most brands
really nicely. A wrap of tape might be needed in the odd
case for a good friction fit but it is probably not
necessary in most cases.
- I mix my epoxy with a 3/32" stainless steel rod
about 8" long on a sheet of glass. I find that it
works well to mix and scoop up, and when set, the excess
scrapes right off with a razor knife. Spread it out thin
to make clean up real easy.
- The wooden sticks that come with those frozen treats on
them. I 'made' my wife and daughter eat a lot of frozen
ice and save the sticks for nearly a year. I now have a
box full and I find them to be real handy around the
modeling workshop.
- For sanding hard to reach spots, I have taken a popsicle
stick and glued a piece of sand paper on to it. Makes a
good sanding stick. I put various grades of emery paper
onto the popsicle sticks with CA. When the paper becomes
plugged and can't be washed out anymore or worn out, I
glue another stick onto a piece of sandpaper and slice it
off for another 'quick sanding stick'. Sometimes I just
glue a fresh piece of sandpaper on top of the one that is
worn/plugged. If a person were organized they would
prepare a bunch of them for use at will and use wood glue
(yellow or white), but I make them when I need them,
hence CA.
- Time will tell if my hinge scheme will hold up. I've got
6 flights on my heli-recovery unit. So far no signs of
wear in the hinges. Take Gorilla Braid fishing line, wrap
it 7 times around a bt-50, laid up side by side. Then
stick the lines together with a piece of masking tape and
make a cut through the tape across the lines. You will
then have a 7 line 'braid' a couple of inches long with a
piece of tape on each end. Take tape off one end, glue to
body tube, take tape off other end, glue to rotor. I used
CA, and some wicked up into the part of the 'braid' that
flexed. But after it dried I just flexed it until it was
limber enough to work properly. Like I said, so far, so
good. I have since located some plastic R/C hinges that I
intend to try for my next heli-style.
- I had a large cardboard box that I cut a door into (cut
one side and top and bottom of the door and make a crease
for the hinge). I had a long 3" x 3" box from a
telepost that I inserted through the back of the 'booth'
for a duct, right through and attached it to just above
the 'door'. I cut a slot into the bottom of the 'square
cardboard duct'. This 'duct' protrudes out the back of
the 'booth' by thirty inches or so. I then put a piece of
plastic tubing through the front of and into the duct,
all the way past the slot ending just past the back of
the 'booth'. I ran my air line with blower nozzle into
the end of the tubing and sealed it with tape and
then with the valve open with a small clamp or tape the
rushing air causes a venturi and draws paint fumes into
the slot and out the 'duct'. To use this, I open my
shop's drive-in door just high enough for the box, and
put a part sheet of plywood on either side of the box
blocking the rest of the open doorway. It worked
amazingly well. I wear a filter mask when painting as
there is some cloud formed at the door of the booth. When
I have enough paint on the rocket, I close the door most
of the way, and any fumes nearby get sucked into the
booth. After a few minutes I turn the air off and there
is very little fume buildup in the shop and most of the
over spray is contained. One could filter the duct, but
this outfit is temporary. I just don't park in front of
it. Someday I plan to get setup with a fan, real ducting
through the wall and a full blown plywood booth with
filters and rotisserie (vertical and horizontal). But I
had all these rockets to finish and needed a quick fix.
- Peizo buzzers are well worth the investment. They do work
in given situations rather well. If you track your rocket
back to the ground you can usually walk to a position
close enough to it that the audible tone will be -- well
-- audible. I built one of them from a few dollars worth
of parts, basically ....a battery, a peizo buzzer, a
flashing LED and a small chunk of perf. board .... fits
in a bt-20. For my bigger rockets I use a 'rape' alarm,
one of those personal alarms sold in hardwares, Radio
Shack etc.; they can be picked up for under $10, as low
as $4.
- When a knot is tied in a rope it is considered to have
lost 50% of it's strength, when a bend is tied in a rope
it is also considered to have lost half of it's strength.
When a hitch is used the rope strength is reduced by 25%
while an eye splice or short splice is factored at 20%
reduction. If you bend two ropes in a 'U' around each
other the strength is reduced by 50%. 50% is considered
an acceptable degree of rope strength as most ropes are
rated with a 5-1 safety factor, that is to say for
example: 5/8" nylon rope with a rating of 2000 lbs.
would actually take a static load of 10,000 lbs. before
breaking and with a knot only 5,000 lbs. I have used
bowlines, clove hitches, reef knots, sheetbends,
half-hitches and figure-eights in my recovery systems.
With bowlines I always tie an inside bowline with the
tag-end half-hitched to the loop. It tends to stop the
migration of the tag end under no load situations. I
usually use a round-turn and two half-hitches to tie to a
quick link and that is probably prefered although a clove
hitch to the quick link with a couple half-hitches to the
standing end would do.
- Braided fishing line makes great suspension lines for
your home-made parachutes (parasheets would be more
correct, but heck almost everyone calls 'em 'chutes
:>) and works for shock cord in lightweight models
like 1/4 A PD contest models. I use Gorilla Braid, it is
soft and really supple. Your knots have to be real ones,
no granny knots allowed. Use knots for slippery or wet
line. Double sheet bend, surgeons knot, fishing line
hitch (can't remember the name, you know the
one...through the eye of the hook, up around the line 5
times, back down through the loop and up through the
loop, cinched down onto the eye. Not my favorite for this
braid, but tied right will work. Check out http://www.mistral.co.uk/42brghtn/knots/42ktmenu.html
for some basic knots.
- Here's a good way to make octagon 'chutes...take a square
of material (garbage bag, nylon, dry cleaner bag, mylar
wrapping paper...whatever grabs ya)(or is that whatever
ya grabs) take your square and fold it in half, then fold
in half again forming a square 1/4 the size you started
with. Note which corner is the center of the original
square. Make your next fold corner to corner keeping the
'center' of your original square on the fold line. This
gives you a 45 degree triangle. Fold once more keeping
the 'center' of your original square on the fold line
giving you a 22.5 degree triangle. Now cut along the
bottom of your triangle, cutting off the excess. Unfold
for a near perfect octagon. Practice this on a piece of
paper until it works.
- I have to attribute my plastic chute fold technique to my
experiments with the little toy parachuting soldiers that
you throw up into the air. I started my tests with the
classic Estes method -- pinch the peak of the chute, fold
the edges over, fold the peak down to the skirt, roll up
and wrap the suspension lines around. Nearly every time I
ended up with a plastic wad recovery, killing many toy
soldiers. I eventually had the little toy soldiers
deploying at or before apogee every time. After a bunch
of trial and error, I finally settled on the following
with appropriate mods for use in rockets...
-Spread the chute out so the skirts line up.
-Fold over in half with the fold from skirt to peak, now
you have four sections of skirt lining up.
-Fold once more giving you eight skirt sections lined up,
creating a triangle.
-Figure eight the suspension lines around two fingers and
lay them onto the bottom of the triangle.
-Fold the peak down to the skirt.
-Fold one side to the middle.
-Fold the other side to the middle.
-Repeat the last two steps until you have a thin cylinder
of chute that should slip into the airframe.
-If it is too long you may have to Z-fold when folding
the peak down to the skirt so that the peak is pointing
back up and then fold the edges in.
-Figure eight your shock cord into the airframe, place
the shock cord from the nose under the chute as you are
sliding it in so that as the nose comes off, it pulls the
chute out with it.
-I typically put the top of the chute down so that the
suspension lines and skirts are more protected from the
ejection charge.
Clear as mud? I thought so.
Oh yeah, don't forget the talc. Those plastic chutes need
to be well chalked both sides. I use carpenters chalk, it
gives a little color to the dry cleaning bag and gets rid
of that static cling.
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