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| Leslie Houk... |
 Posted: Fri Oct 30, 2009 9:55 am |
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I haven't seen many postings in RMR lately, so I thought I would try
to get a thread started. Do you have a tip or idea for your fellow
model rocketeers? If so, post it, and let's see if we can make RMR
useful again.
To start off, here's an idea I haven't seen elsewhere. The narrowest
roll of masking tape I've seen is 3/4 inch, but sometimes you need it
to be thinner. For example, to make a thrust ring on a 13mm engine,
or to secure an engine hook to a 24mm reload engine. In those
situations, I use floral tape -- the green tape that florists use to
make flower arrangements. It's cheap, available in any craft or
floral store, and comes in 1/2 inch widths.
Anyone have any other tips?
Leslie |
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| DJ Delorie... |
| Posted: Fri Oct 30, 2009 2:10 pm |
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Use slow-setting epoxy for larger body tubes - yellow glue grabs too
quickly, risking an incomplete connection between parts if it grabs
before you're done inserting the BT. |
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| Leslie Houk... |
| Posted: Mon Nov 02, 2009 10:47 am |
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To make sure your fins and launch lugs are straight on your body
tubes, you have to make sure your guide lines are drawn straight along
the length of the tube. My favorite way to do this is by using angle
irons -- "L"-shaped lengths of metal -- as a guide when drawing the
lines.
My local Ace Hardware store sells 1/2" x 1/2", 3/4" x 3/4" and 1" x 1"
aluminum angle irons in 4' lengths. If you don't have a local
hardware store that carries them, one online source is http://www.onlinemetals.com,
which sells 6063-T52 aluminum angle irons in various widths and
lengths. (I'm sure there are other sources, but that's the first one
I found while searching online). |
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| Leslie Houk... |
| Posted: Thu Nov 12, 2009 7:23 am |
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White glue is great for model rockets, but when you start building mid-
power and larger rockets, you need to use epoxy. When I use it, I
tend to repeatedly mix small amounts -- for example, mix a little up
and make fin tang fillets inside the body tube, wait for them to dry,
rotate the rocket 90 degrees, and repeat three more times. I've found
it handy to keep a box of toothpicks and a box of kitchen wax paper in
my workshop. When I need some epoxy, I tear off enough wax paper to
give me a mixing surface, and use a toothpick to mix it.
The toothpick is also good for applying the mixed epoxy to accessible
areas, but for applying it to recessed areas in a body tube I use
shish kebab skewers. You can get a bag of 100 ten-inch skewers at
most grocery stores for a couple of dollars. |
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| Bob... |
| Posted: Fri Nov 13, 2009 2:29 am |
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On Nov 12, 11:23 am, Leslie Houk <lh... at (no spam) ghg.net> wrote:
Quote: White glue is great for model rockets, but when you start building mid-
power and larger rockets, you need to use epoxy.
A common fallacy.
While I'd use yellow glue instead of white glue for my models, yellow
glue works fine on any size rocket as long as the materials being
bonded are wood and paper. In fact, any good yellow glue is going to
make a stronger bond between wood and paper than 5 minute, 30 minute,
and even the aircraft/boat building epoxies like West and System3. The
mass market epoxies just won't hold up to motor mount heat, even on a
rocket as small as a Mosquito.
I tested this to the extreme over a decade ago, building a THOY Hornet
(same size as a Graduator or Initiator, 29mm MMT, I added a baffle
system to the MMT) with nothing but Titebond. To date it's flown on
everything from a D to an H238, which is the limit of what will fit in
the motor mount.
A rocket like a LOC Magnum, a popular L2 kit, would have no problem
flying on a J or more even built with Titebond.
Of course regardless of glue, you need to use proper building
techniques everywhere, such as fillets and reinforcing where needed.
When you switch to materials like G10, fiberglass, and the like, then
you do need to use epoxy. But not until then. |
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| Leslie Houk... |
| Posted: Fri Nov 13, 2009 12:21 pm |
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On Nov 13, 6:29 am, Bob <bobkap... at (no spam) yahoo.com> wrote:
Quote: On Nov 12, 11:23 am, Leslie Houk <lh... at (no spam) ghg.net> wrote:
White glue is great for model rockets, but when you start building mid-
power and larger rockets, you need to use epoxy.
A common fallacy.
...
When you switch to materials like G10, fiberglass, and the like, then
you do need to use epoxy. But not until then.
I stand corrected. Thanks for the tip! |
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| §... |
| Posted: Mon Nov 16, 2009 1:00 pm |
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Leslie Houk wrote:
Quote: I haven't seen many postings in RMR lately, so I thought I would try
to get a thread started. Do you have a tip or idea for your fellow
model rocketeers? If so, post it, and let's see if we can make RMR
useful again.
To start off, here's an idea I haven't seen elsewhere. The narrowest
roll of masking tape I've seen is 3/4 inch, but sometimes you need it
to be thinner. For example, to make a thrust ring on a 13mm engine,
or to secure an engine hook to a 24mm reload engine. In those
situations, I use floral tape -- the green tape that florists use to
make flower arrangements. It's cheap, available in any craft or
floral store, and comes in 1/2 inch widths.
Anyone have any other tips?
One of my favorite tips is to use Future floor wax for the clear coat.
After the flying season is over I use Windex to remove the clear coat
and redo the process for the next flying season.
Ted Novak
TRA#5512 |
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| Peter Fairbrother... |
| Posted: Mon Nov 16, 2009 9:19 pm |
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§ wrote:
Quote: Leslie Houk wrote:
I haven't seen many postings in RMR lately, so I thought I would try
to get a thread started. Do you have a tip or idea for your fellow
model rocketeers? If so, post it, and let's see if we can make RMR
useful again.
To start off, here's an idea I haven't seen elsewhere. The narrowest
roll of masking tape I've seen is 3/4 inch, but sometimes you need it
to be thinner. For example, to make a thrust ring on a 13mm engine,
or to secure an engine hook to a 24mm reload engine. In those
situations, I use floral tape -- the green tape that florists use to
make flower arrangements. It's cheap, available in any craft or
floral store, and comes in 1/2 inch widths.
Anyone have any other tips?
One of my favorite tips is to use Future floor wax for the clear coat.
After the flying season is over I use Windex to remove the clear coat
and redo the process for the next flying season.
Not a tip as such, but - has anyone tried dimpling a rocket, like a
golf-ball?
It's been tried with cars, and they do go faster ...
-- Peter Fairbrother |
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| ... |
| Posted: Sat Nov 21, 2009 5:22 am |
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Pet shops sell 12" and 16" long "tweezers" used to reach into spider tanks.
They work great for grabbing things inside those small diameter airframes.
Kevin |
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| Leslie Houk... |
| Posted: Sat Nov 28, 2009 9:07 am |
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On Nov 16, 8:19 pm, Peter Fairbrother <zenadsl6... at (no spam) zen.co.uk> wrote:
Quote:
Not a tip as such, but - has anyone tried dimpling a rocket, like a
golf-ball?
It's been tried with cars, and they do go faster ...
-- Peter Fairbrother
No one else has replied yet? I haven't heard of anyone trying this.
My off-the-cuff thought is that any gain in a rocket's aerodynamics
would be offset by the additional weight of the rocket coating, but
that's just a guess. This sounds like a possible NARAM R&D project.
Build a couple of rockets, one with dimpling and one without, and see
if one performs better. |
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| Alan Jones... |
| Posted: Sun Nov 29, 2009 9:40 pm |
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On Sat, 28 Nov 2009 11:07:59 -0800 (PST), Leslie Houk <lhouk at (no spam) ghg.net>
wrote:
Quote: On Nov 16, 8:19 pm, Peter Fairbrother <zenadsl6... at (no spam) zen.co.uk> wrote:
Not a tip as such, but - has anyone tried dimpling a rocket, like a
golf-ball?
It's been tried with cars, and they do go faster ...
-- Peter Fairbrother
No one else has replied yet? I haven't heard of anyone trying this.
My off-the-cuff thought is that any gain in a rocket's aerodynamics
would be offset by the additional weight of the rocket coating, but
that's just a guess. This sounds like a possible NARAM R&D project.
Build a couple of rockets, one with dimpling and one without, and see
if one performs better.
One of my favorite rockets was a Big Bertha painted white and covered
with metal flake blue punched paper computer tape (an old altitude
prediction program). It was purely cosmetic, but it may also qualify
as a dimpled surface.
In your research, be sure to learn about separated flows, and how the
type of boundary layer affects separation. If you find a rocket
design that may benefit from inducing boundary layer transition, you
can research more effective ways of tripping the boundary layer on the
rocket than dimpling. You might also discover that using vortex
generators can be even more effective.
Dimpling etc. will not improve a typical well designed rocket,
although you may find an exception. In general you just want a well
built and finished model with a rubbed/waxed finish.
Alan Jones |
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