LOC graduator

LOC graduator

Post by guy wal » Thu, 10 Jul 1997 04:00:00



any suggestions on building the graduator.  in particular, i noticed that
the ttw fins do not go to the mmt.  anyone had a problem with this?

 
 
 

LOC graduator

Post by Mhollih » Thu, 10 Jul 1997 04:00:00


The Graduator is a great kit, and very tough and stable.
For the TTW fins, I lined up the centering rings so that they butted up
against the tabs of the fins.  Then I bought some dowel (I forget the
size, but almost as large as the tab that sticks through the body tube.)
and cut six lengths that would fit snugly between the centering rings.  I
attached a pair of these so that they were on either side of each slot in
the body tube and epoxied them in place.  This formed a "cage" that would
trap each fin and increase the area that could be reinfornced, as well as
distributing the fin load.  I laid a large amount of epoxy in a channel,
then inserted the fin.  I turned the rocket over (so that the fin pointed
down) and let it dry.  The idea is to get enough epoxy in the channel that
is covers the fin, dowel, and runs back over to the body tube.  I found
that this created a very strong joint and did not negatively affect
stability.  This rocket even took bad recoveries and still didn't snap the
fins!

I did my Level I cert on this rocket with an H97, and sent it to 3000
feet!

Mike Hollihan
Mid-South Rocket Society
NAR# 53545
TRA# 4309

Quote:

>Date: 9 Jul 1997 08:57:54 GMT

>any suggestions on building the graduator.  in particular, i noticed that
>the ttw fins do not go to the mmt.  anyone had a problem with this?


 
 
 

LOC graduator

Post by Alex Merica » Thu, 10 Jul 1997 04:00:00


Quote:

> any suggestions on building the graduator.  in particular, i noticed that
> the ttw fins do not go to the mmt.  anyone had a problem with this?

The Graduator is a great kit.  Invest in a third centering ring for the
engine tube.  Put one near the top of the engine tube, one just above
the fin tab and one just below.  The fin tabs should touch the rings
and you should spread epoxy across the joint.  Wait until the fins are
glued to add the last ring.  That way you have access to the back side
of the tube/fin joint.  Spread epoxy across this joint; a bit of fiberglass
cloth will add some strength.  Consider adding a motor retention device such
as the Kaplow Clip.  Masking tape works ok, but the clip looks better.

The Grad flies great on single use and reloadable F & G's.  A G64 gives a
fantastic flight.  

If you fly near concrete you WILL eventually crack a fin.  This happended
three times to me, twice on the same fin.  Just epoxy it back together and
keep flying.  Even after field repairs (masking tape and SuperGlue) my
Graduator flew very straight.

If you fly near high grass or corn fields, consider adding a LOUD buzzer.  
The Grad is not very heavy and will drift quite a bit.  I lost mine in a
corn field :-(

--

Alex Mericas

 
 
 

LOC graduator

Post by Foxe » Fri, 11 Jul 1997 04:00:00


Quote:

>any suggestions on building the graduator.  in particular, i noticed that
>the ttw fins do not go to the mmt.  anyone had a problem with this?



yep, this is true of this kit, however if you wish to make them extend
to the mmt its really a simple matter, and does make for a much more
durable rocket.  My son just got finished with this kit, and cut new
fins to reach to the mmt, and added a 3rd CR as well, along with
positive motor retention, it should prove to be a fairly substantial
build.  If my son and I can make the fins to the mmt, we do so in
every rocket we build, in some cases its actually overbuild, but we
found the fins are less prone to comming off.

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services.  Take the www out of address to send email.
 
 
 

LOC graduator

Post by Mhollih » Fri, 11 Jul 1997 04:00:00


Uh...later in the day, I realized that you could use an easier path to
constructing the "cage" I described.
Cut the six dowels as before.  Glue on the forward centering ring, and
place the rear centering ring on the MMT to keep it straight.  Epoxy this
in the body tube so that the rear of the forward centering is flush with
the top of the fin slot.  Let this set up, then remove the rear CR.
Tack-glue the fins in place, using quickset epoxy or CA.  Lay one dowel on
each side of the fin tab, working one at a time, and lay on the epoxy.  
After this sets up, smear a ring of epoxy around the back of the body tube
and put on the rear CR.  Fillet the fins as usual.
This is easier than cutting new fins (really!) and still strong.

Mike Hollihan
Mid-South Rocket Society
NAR# 53545
TRA# 4309

 
 
 

LOC graduator

Post by mitymi » Fri, 11 Jul 1997 04:00:00


Quote:

> any suggestions on building the graduator.  in particular, i noticed that
> the ttw fins do not go to the mmt.  anyone had a problem with this?

Not a problem...get another centering ring...take a divider and measure
off the distance of the MMT/BT on the fin...'clip' the front of the
fin...use 'extra' centering ring at front of fin...use slots in body
tube to align fins...after gluing this all up...move the C/G forward
with a pack (125) BBs...glue these into the nosecone.

This is the same as a rocket i built from scratch a few years ago...I
retired that one and recently built another one from a graduator kit as
described above. It flys GREAT.