Launch Rod?
Rick Morin
rods/rails really nessecary for larger rockets? I know rods were important
to those small Estes rockets I used to fly, but what is the importance to
the heavier rockets? Do they really get the rocket off to a strait start, or
what? I dont plan on launching in winding conditions, where a rail or rod
might be usefull in pointing the rocket at the the right angle into the
wind. Keeping the rockets off the grass isnt a problem where I fly either.
The only thing I can think of is getting the rocket flying in the right
direction, but I cant imagine that being a big factor in the larger HP
rockets. Any input is appreciated!
Thanks!
-Rick Morin
David Weinshenker
> Hey everyone. This might be a stupid question,
> but what the heck: Are launch rods/rails really
> nessecary for larger rockets?
Yes - in fact they use larger ones, in proportion.
HPR's typically use 1/4-1/2 in. rods, or sturdy C-rails.
-dave w
Rick Morin
Thanks for responding, but that really doesn't answer my question. I know
that they use rods, as I do, but I was wondering if they are necessary for a
stable flight.
Thanks again, and happy Thanks Giving.
-Rick Morin
"David Weinshenker" <daz...@grin.net> wrote in message
news:3A1D93C7...@grin.net...
Dick Stafford
the flight of the rocket until it's speed is sufficient for the fins (or
cone, ring tail, etc) to control the rocket's stability. The required
length of the launch guide is dependent on the rocket's aerodynamics,
weight, and engine selection. Even if there is NO wind, there will be
forces working that will cause your rocket to move on its pitch/yaw axes.
You should probably get a book such as Stine's 'Handbook of Model Rocketry'.
Tim Van Milligan's 'Rocket Design and Construction'
(http://www.apogeerockets.com/design_book.asp) probably also discusses this
subject.
While putting in a plug for Apogee, you can 'experiment' with different
launch guide lengths using the Rocksim program.
--
Dick Stafford
TRA# 6578 L2
"Rick Morin" <trit...@pacbell.net> wrote in message
news:9dgT5.53$7e7....@news.pacbell.net...
> Hey everyone. This might be a stupid question, but what the heck: Are
launch
DLogan
direction for the first few feet at lift off, until the rocket reaches a
speed at which it becomes stable. I'm not exactly sure what the standards
are, but I believe the acceptable speed should be some where around 35-40
ft/second to be considered stable. David.
David Weinshenker
> Dave,
> Thanks for responding, but that really doesn't answer my
> question. I know that they use rods, as I do, but I was
> wondering if they are necessary for a stable flight.
Yes. Any rocket, large or small, needs the guidance of the
rod until at a speed where the fins will effectively stabilize
it - at the beginning of the motion, the speed is near zero,
and so is the aerodynamic "straightening force" which the fins
generate.
This need does not change with the size of the rocket, unless
you're talking about actve guidance (computer-controlled
vectored thrust, etc.) as used in the really large rockets
(i.e., orbital ones).
Even the largest free-flight fin-stabilised rockets, such as
industrial sounding rockets, use some sort of rail or similar
guiding device at launch, to stabilize the rocket until it
picks up enough speed for the fins to be effective.
-dave w
R. J. Talley
its side and become a rather lethal missile. If we didn't need a rod or rail
we wouldn't use one. All of NASA's missiles use either a rail or a gyro or
both. Surface to air missiles use a rail. Even sea launched missiles use a
tube until sufficient speed is attained. Shoot, bazookas and other shoulder
fired rockets use tubes or rails. Take it from the experts, you must have
either a rail or a rod.
--
R. J. Talley
NAR 69594
"To do is to be"...Descartes
"To be is to do"...Voltaire
"Do be, Do be, do"...Sinatra
"Rick Morin" <trit...@pacbell.net> wrote in message
news:RBgT5.56$7e7.1...@news.pacbell.net...
> Dave,
>
> Thanks for responding, but that really doesn't answer my question. I know
> that they use rods, as I do, but I was wondering if they are necessary for
a
> stable flight.
>
> Thanks again, and happy Thanks Giving.
> -Rick Morin
>
>
> "David Weinshenker" <daz...@grin.net> wrote in message
> news:3A1D93C7...@grin.net...
> > Rick Morin wrote:
> > > Hey everyone. This might be a stupid question,
> > > but what the heck: Are launch rods/rails really
> > > nessecary for larger rockets?
> >
Jim Ball
> Hey everyone. This might be a stupid question, but what the heck: Are launch
> rods/rails really nessecary for larger rockets? I know rods were important
> to those small Estes rockets I used to fly, but what is the importance to
> the heavier rockets? Do they really get the rocket off to a strait start, or
> what? I dont plan on launching in winding conditions, where a rail or rod
> might be usefull in pointing the rocket at the the right angle into the
> wind. Keeping the rockets off the grass isnt a problem where I fly either.
> The only thing I can think of is getting the rocket flying in the right
> direction, but I cant imagine that being a big factor in the larger HP
> rockets. Any input is appreciated!
>
> Thanks!
> -Rick Morin
Launch rails are used on even the largest professional sounding rockets. It
provides that extra margin of safety and stability until the rocket is moving at
sufficient speed for aerodynamic forces to act against the fins.
Jim Ball
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Oliver
--
Thanks
Oliver
Stop losing your rockets!
Check out my rocket locators at http://biznet.maximizer.com/rockets
Dick Stafford
mate with the C-slot are mounted on the rocket. The closest thing I've seen
outside of rocketry are the rails for overhead garage doors and the wheels
which run in them. Some of these items are also adapted for rocketry. Look
at the following site - they sell launch rails. http://www.blacksky.com/
--
Dick Stafford
TRA# 6578 L2
"Oliver" <rockets...@attglobal.net> wrote in message
news:t1rn8cg...@corp.supernews.com...
Mel Sharpe
Kevin Trojanowski wrote in message <3A1DE0C3...@nospam.home.com>...
>Oliver wrote:
>>
>> I have used rods and towers. How do rails work?
>
>down a channel that fits around them.
>That's the basic idea, but rails are a bit fancier.
>
>-Kevin
I made my own "rail" system using an 8 ft straight length of
aluminium caravan (trailer?) awning track.
(It stands out on an arm from the model and medium power rod holder
of my launch system.)
The track usually used on the side of caravans (trailers) to take the
rope edge of a temporary canvas awning that can be put up on campsites.
I would assume that the stuff is available in the US.
I made a timber "T" section by screwing and gluing two 2 X 1 inch battens
together.
I then screwed the awning rail to the base of the "T".
Lugs are made from 30mm long 1/4 inch brass rods soldered to the top of an
"L" section
of brass also 30mm in length.
The "foot" of the L has holes drilled in it.
The foot is pushed through a slot in the BT and epoxied on the inside.
It works perfectly, is fairly cheap (£20 for materials)
and I have the satisfaction of having designed and built it myself.
Regards Mel S
A UK rocketeer
UKRA 1045
Level 2 RSO
Kevin Trojanowski
>
> I have used rods and towers. How do rails work?
Put two rail buttons on the side of the rocket, then slide the buttons
down a channel that fits around them. Picture a dowel glued to the side
of the rocket; take a piece of rigid tubing where the inside diameter is
slightly larger than the outside diameter of the dowel. The tubing has
part of one side cut away along its length, so that when the dowel is
slide down the tube, it allows somewhere for the glue joint between the
rocket and the dowel to exist.
Greg Cisko
news:RBgT5.56$7e7.1...@news.pacbell.net...
> Dave,
>
> Thanks for responding, but that really doesn't answer my question. I know
> that they use rods, as I do, but I was wondering if they are necessary for
a
> stable flight.
Yes they are necessary. The idea is to generate enough speed for the fins
to work *BEFORE* they leave the rod/rail.
--
> Thanks again, and happy Thanks Giving.
> -Rick Morin
>
>
> "David Weinshenker" <daz...@grin.net> wrote in message
> news:3A1D93C7...@grin.net...
> > Rick Morin wrote:
> > > Hey everyone. This might be a stupid question,
> > > but what the heck: Are launch rods/rails really
> > > nessecary for larger rockets?
> >