| Title: | Welcome To The Radio Control Conference |
| Notice: | dir's in 11, who's who in 4, sales in 6, auctions 19 |
| Moderator: | VMSSG::FRIEDRICHS |
| Created: | Tue Jan 13 1987 |
| Last Modified: | Thu Jun 05 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 1706 |
| Total number of notes: | 27193 |
Well, rather than cluttering up the SS note, let's open a new topic...
Bomb Drops...
How does yours work and why do you like it??
I'll start...
My basic design is simple. Pushrod is confined by a conduit (usually
a piece of hardwood with a hole drilled through it. The conduit
has a gap in it that accepts a screw eye. The screw eye is attached
to a 1" round dowel that has a sheet metal screw in the front and
a streamer in the back. The sheet metal screw adds just a little
weight (I believe the max weight of any dropped item is 2oz). I
have also used fishing bobbers using a paper clip to attach the
bomb to the release.
This mechanism is simple to implement, cheap and works very reliably.
There is no strain on the servo. Virtually anything can be used
for a bomb. The variations that I have tried are highly visible.
I also have a "Vortac" bomb drop. This is a preformed piece of
plastic that has a spring loaded release mechanism built in. It
only accepts Vortac style bombs. They do sell just the bomb
attachment.
I never really liked this setup. First of all, unless it is adjusted
just right, you can strain a servo/ drain you Rx pack as it has
a definite stop in travel. Installation of the mechanism itself
is a little more complicated too. However, the bombs that they
supply are hollow and break in half on impact. Thus, you can fill
them with flour for a better effect.
Last fall I devised a way to drop 4 pieces of dowel, one at a time
so that I could practice my bomb drops for Rhinebeck. This mechanism
fed the dowels down through a "magazine". I used a pushrod on both
sides of the servo. One pushrod below the bottom bomb, one pushrod
above it. As the bottom rod moved out of the way to release the
bomb, the top rod moved in to keep the others from falling out.
The magazine has a permanent catch on it so that there are two
points of contact holding the bottom bomb in.
Then, after the drop, I flipped the switch back again. As the bottom
rod moved back into an "armed" position, the top rod moved out of
the way and let the next bomb drop to the release position.
This mechanism workes like a champ. I was able to reliably drop
4 bombs per flight. However, due to the size of the plane and the
location that I wanted to place the mechanism, I had to use very
small pieces of dowel (1/2" round by about 2 inches). Painting
them helped recovery a little, but I was never able to use a streamer
without it getting hung up.
Dan S., why don't you re-explain your idea here (or move your note).
Does anyone else have any variations/other methods they would like
to share??
cheers,
jeff
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 946.2 | here's mine | LEDS::HUGHES | Dave Hughes (LEDS::HUGHES) NKS1-1/E3 291-7214 | Wed Apr 05 1989 16:18 | 52 |
I have a 2 stage drop using a proportional servo that I use for my
streamers. This could be adapted to drop bombs, and could have more
than 2 stages if necessary.
Basically it's a 3/8" dowel, with slots cut into it. A hole is then
drilled through it to pass through the slots, and a pushrod goes down
through the hole. I used a flexible steel cable pushrod (like used on
throttle controls), and the part that goes up and down in the dowel is
tinned with solder for stiffness. The dowel is mounted in the center of
the fuselage, and the servo is on its side inside the fuse. I'll try to
draw a rough picture:
-----+
| ++
| ||
SERVO |=||
| ||-+
| ++ |
-----+ |<- pushrod
|--|-----|
--------------------------|--|-----|--------------------------
| | | ^ fuse bottom
--|--+ |
__|__+ |
| | |
<- rear | | | front ->
| | | <- dowel
--|--+ |
__|__+ |
| | |
|________|
I set it up by tying a string (fishline) to the end of the rolled up
streamer, tying a loop in the string, and sticking the loop in the top
slot. I then put a rubber band (#64 wing bands do nicely) in the
bottom slot, and stretch it over the rolled up streamer and hook
it on two screw eyes that are in the bottom of the fuse on each
edge a few inches behind the dowel (not shown on my crude drawing).
Moving the servo half-way releases the rubber band which falls
off and causes the streamer to unroll. When I'm done with it, I
push the servo all the way up which allows the string to drop
out and the streamer flutters down to the ground.
The proportional servo allows you to release one slot at a time. I've
also heard of a similar setup with dowels out the side of the fuse
instead of bottom. You could put a dowel on each side of the plane and
drop a bomb from each side with one servo. I'm sure Dan could use this
arrangement to have the rubber bands come off the wing under radio
control, so the wing would flutter down to the ground... Sorry, couldn't
resist. I'm sure glad we're all friends here!
Dave Hughes
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| 946.4 | Let's Do It! | LEDS::WATT | Thu Apr 06 1989 09:19 | 8 | |
Eric,
Let's plan a time to get together on this. I think we can fairly
quickly determine if it's doable with your PCM radio. It's
straight forward with the older units that use the Signetics chip set.
I'm going crazy being grounded for a week with the wet weather.
Charlie
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| 946.5 | SA1794::TENEROWICZT | Thu Apr 06 1989 10:04 | 5 | ||
If (and when) we are going to have a DEC SPRING FLY-IN???????? why
don't you guys plan on having a bomb drop competition??
Tom
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