LOC/Onyx construction questions

LOC/Onyx construction questions

Post by Yves Lacom » Fri, 20 Dec 1996 04:00:00



Hi There.

Okay -- I purchased a LOC Onyx kit and have already begun to assemble
it (the engine mount is already glued in).   Contrary to most LOC
kits, this one doesn't use through-the-wall construction.  Instead, it
uses surface mounting for it's fins.   I heard someone mention using
"Epoxy Rivets" to increase the strength of the bond between surface
mounted fins and the body tube.

Can somebody describe to me the technique in detail?

Also, since I've already installed the engine mount in the rocket, I
can't setup a nut-and-bolt type of engine retention system.  As an
alternative, I was thinking of screwing in two "eyelets" on each side
of the engine mount, and use a strong piece of wire, wrapped through
the eyelets and over the shoulder of the engine (without obstructing
the nozzle) to hold the engine in place.  Has anybody used this
technique before?  And does it work well?

--
Yves

 
 
 

LOC/Onyx construction questions

Post by Bruce E. Bigelo » Fri, 20 Dec 1996 04:00:00




Quote:
> Can somebody describe to me the technique in detail?

"Epoxy rivets" are made by making small holes in the body tube where the
root edge of the fin will attach.  Then, when you epoxy the fin to the
tube, use a bit too much epoxy and make sure some of it runs down into the
small holes.  (Actually, I usually force some down the holes with a
toothpick first, then put epoxy on the root edge of the fin and stick it on
over the holes.  The epoxy will form blobs inside the body tube after it
flows through.  Since the blobs are bigger than the hole, they can't pull
back out after they harden.  This is sort of like the head of a rivet,
hence the name.

How big is a "small hole", you ask?  It depends on the scale of the rocket,
but about 1/16" has worked well for me.  If they're too small, the epoxy
won't go through very well.  If they're too big, they can weaken the
airframe.

I've also heard of people making holes next to the fin after it's in place
and using epoxy rivets under the filets, too.  I've not tried that method
myself.

Good Luck with it.

Bruce

 
 
 

LOC/Onyx construction questions

Post by Erik Benne » Fri, 20 Dec 1996 04:00:00


Quote:



> > Can somebody describe to me the technique in detail?
> How big is a "small hole", you ask?  It depends on the scale of the rocket,
> but about 1/16" has worked well for me.  If they're too small, the epoxy
> won't go through very well.  If they're too big, they can weaken the
> airframe.

I prefer to make the hole the same size of the fin root edge, either
1/8 inch, 1/16 inch etc. I also like to apply a fiberglass layer
over the fins. Makes it really strong. With this done, H flights
are possible, or if you like a kick and can get the Vulcan G200s.

Quote:
> I've also heard of people making holes next to the fin after it's in place
> and using epoxy rivets under the filets, too.  I've not tried that method
> myself.

I would fiber glass instead, but that is just my $.02. For nice filets,
use PC/7. It's sandable and STRONG. BTY if you fiber, you should not
need filets on an Onyx.

--

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LOC/Onyx construction questions

Post by Bart Hackemac » Fri, 20 Dec 1996 04:00:00


Quote:

> Hi There.

> Okay -- I purchased a LOC Onyx kit and have already begun to assemble
> it (the engine mount is already glued in).   Contrary to most LOC
> kits, this one doesn't use through-the-wall construction.  Instead, it
> uses surface mounting for it's fins.   I heard someone mention using
> "Epoxy Rivets" to increase the strength of the bond between surface
> mounted fins and the body tube.

> Can somebody describe to me the technique in detail?

> Also, since I've already installed the engine mount in the rocket, I
> can't setup a nut-and-bolt type of engine retention system.  As an
> alternative, I was thinking of screwing in two "eyelets" on each side
> of the engine mount, and use a strong piece of wire, wrapped through
> the eyelets and over the shoulder of the engine (without obstructing
> the nozzle) to hold the engine in place.  Has anybody used this
> technique before?  And does it work well?

> --
> YvesA couple things that I did with a LOC Lil' Nuke.  Design is

fairly similar to the Onyx.

1.  I did not use e-rivits but used the same trick that was mentioned
in my VB24.  I cut slots 1/2 way through the airframe the length of
the fins and slightly wider.  Then epoxy'ed the fins in these
channels.  Basically one very large epoxy rivit...

2.  I used one of the tips that was in one of the sports rocketry.
Use wood inserts and build some small brass clips that could be
held in by bolting to the wood inserts.  I have used both brass
and steel inserts.  Steel is much preferable in that they are
much easier to place in the centering ring without breaking the
insert.  Also most of the steel inserts are inserted using
an allen wrench rather than the slot screwdriver approach for
brass.  Also known as the Kaplow Klip.

I also tend to over-engineer/secure everything that I build.  
So...  I have drilled a small hole in the base of two of the
fin roots.  Why you ask...  I use this wire as a last resort
retention method by using some light guage safety wire wired
through the hole in the fin and then through a small hole drilled
in the rear closure.  (I know that "technically" that may
be considered a modification of a motor.  If you do not want to
modify the motor, you can use the wrapping method you mentioned
in your note.)

Have fun!

 
 
 

LOC/Onyx construction questions

Post by Bruce E. Bigelo » Sat, 21 Dec 1996 04:00:00




Quote:
> 1/8 inch, 1/16 inch etc. I also like to apply a fiberglass layer
> over the fins. Makes it really strong. With this done, H flights
> are possible, or if you like a kick and can get the Vulcan G200s.

> I would fiber glass instead, but that is just my $.02. For nice filets,
> use PC/7. It's sandable and STRONG. BTY if you fiber, you should not
> need filets on an Onyx.

I'll second the use of Fiberglas cloth -- I do it all the time in my HPR
activities.  (I guess I didn't mention it because Yves didn't ask -
shortsighted if me.)  I'd strongly recommend an article in the August 94
issue of HPR magazine by Jim Rosson -- the textbook on Fiberglasing IMHO.

Bruce

 
 
 

LOC/Onyx construction questions

Post by Award » Sat, 21 Dec 1996 04:00:00


The biggest motor I ever flew in my Onyx was a G110 Blue Thunder and the
regular epoxy fillets held fine. You probably don't need alot of
reinforcement since it has plywood fins and is a lightweight model.

The only time a fin ever broke off of my Onyx was when a kid that was
chasing the recovery stepped on it.

Tracy
Tracy Dungan
Tripoli OK
Midwest Trophy MFG

 
 
 

LOC/Onyx construction questions

Post by DG » Sat, 21 Dec 1996 04:00:00


Quote:

> Hi There.

> Okay -- I purchased a LOC Onyx kit and have already begun to assemble
> it (the engine mount is already glued in).   Contrary to most LOC
> kits, this one doesn't use through-the-wall construction.  Instead, it
> uses surface mounting for it's fins.   I heard someone mention using
> "Epoxy Rivets" to increase the strength of the bond between surface
> mounted fins and the body tube.

> Can somebody describe to me the technique in detail?

Actually, if you just sand off the body tube gloss in the area of the
fin with 100 grit and use reasonably-sized 30-minute epoxy fillets (with
or without glass or graphite "whiskers") you should be fine for anything
up to an H238.  I have an Onyx and it flies great! I did add 1/2 oz. of
lead to the nose cone just in case I want to fly it with an H97 someday.

Quote:

> Also, since I've already installed the engine mount in the rocket, I
> can't setup a nut-and-bolt type of engine retention system.  As an
> alternative, I was thinking of screwing in two "eyelets" on each side
> of the engine mount, and use a strong piece of wire, wrapped through
> the eyelets and over the shoulder of the engine (without obstructing
> the nozzle) to hold the engine in place.  Has anybody used this
> technique before?  And does it work well?

I've used safety wire, but it gets bad reviews with most RSO's.  You can
still put a T-nut in the centering ring. Just drill a hole big enough
for the center stud to fit into and carfully drive the T-nut in from the
outside.  Install a bolt, then add enough epoxy to cover over the entire
T-nut (You'll need very little epoxy if you make sure the T-nut is all
the way in).  If you want, you can lighten the epoxy with glass
microspheres, just make sure that the viscosity stays low enough to
"flow".  When the epoxy is almost but not yet completely hardened,
remove the bolt.  Voila.

DG
TRA #4666

"Great discoveries and improvements invariably involve the cooperation
of many minds."
      --Alexander Graham Bell

 
 
 

LOC/Onyx construction questions

Post by Mike Vande Bu » Sat, 21 Dec 1996 04:00:00


: 1.  I did not use e-rivits but used the same trick that was mentioned
: in my VB24.  I cut slots 1/2 way through the airframe the length of
: the fins and slightly wider.  Then epoxy'ed the fins in these
: channels.  Basically one very large epoxy rivit...

I did something very similar on my Onyx.  Rather than cutting halfway
through the airframe, I just cut lightly and removed only the glassine outer
surface of the tube.  (I cut a rectangular area the size of the fin root.)
After the fins were mounted, I could _see_ the area of discoloration where
the epoxy (12 minute) had soaked into the tube.  Then I put on the fillets.
Next time I may make the cut area larger so that the base if the fillets can
soak in, too.  This is probably not stronger than epoxy rivets, but it is
easier and I think it is "strong enough."

--

 
 
 

LOC/Onyx construction questions

Post by Bob Kapl » Sun, 22 Dec 1996 04:00:00


Quote:


>> Also, since I've already installed the engine mount in the rocket, I
>> can't setup a nut-and-bolt type of engine retention system.  As an
>> alternative, I was thinking of screwing in two "eyelets" on each side
>> of the engine mount, and use a strong piece of wire, wrapped through
>> the eyelets and over the shoulder of the engine (without obstructing
>> the nozzle) to hold the engine in place.  Has anybody used this
>> technique before?  And does it work well?

> I've used safety wire, but it gets bad reviews with most RSO's.  You can
> still put a T-nut in the centering ring. Just drill a hole big enough
> for the center stud to fit into and carfully drive the T-nut in from the
> outside.  Install a bolt, then add enough epoxy to cover over the entire
> T-nut (You'll need very little epoxy if you make sure the T-nut is all

Not on an Aura. In fact T-nuts are designed to work the other way, and mounting
them with the plate outwards can lead to them pulling out, even with epoxy to
hold them in.

But on the Aura specifically, there is no room for a T-nut on either side. The
MMT is 29mm. The body tube is 38mm. (38-29)/2=4.5mm minus wall thickness.
There's barely room here for the brass/steel inserts. Even my micro t-nuts
wouldn't fit here.

The other alternative is to reverse the process. Drive two threaded rods in the
space between the MMT and the tube. Have them extend a bit past where the end
of the motor will be. Nuts and possibly washers over those rods will grab the
motor form both sides and hold it in.

When I first started with HPR/LMR, I got the LOC experimenters kit. I put a
24mm mount in one of the 38mm tubes, which esentially was then a scratch built
Aura. It is retro-fitted with the brass inserts.

        Bob Kaplow      NAR # 18L       TRA # "Abort, Retry, Fail?"

 
 
 

LOC/Onyx construction questions

Post by Yves Lacom » Sun, 22 Dec 1996 04:00:00


I'd like to thank everyone with the great advise.  This is one of my
first LOC kits, all the other kits I've assembled are from the
Aerotech line which makes the job pretty easy for us BAR's starting up
in Mid and High-Power rocketry.

I finally opted for epoxy rivets.   I didn't use a drill, just a
fairly thick needle to punch 1/16" (approx) holes along the location
where the fin root edge will be, spaced about 1/4" apart.  I then
glued the fin in place with 10 minute epoxy first, let it dry, then
applied 30 minute epoxy for the filets.  That should be pretty strong.
I didn't forget to sand the glassine off first either.

I was toying with the idea of glassing the fins, but I've never done
it before and I'm not sure if I wanted to add all the extra weight.
Composite engines don't come cheap here in Canada, and I don't like
the idea of needing an H to lift the bird off the ground each time I
take it out.  ;-)

As for the engine mount, I used the method I described.   Someone
mentionned "safety wire".  I don't know what that is.  I just use a
fairly thick electrical copper wire that I wrap across the engine
shoulder with loops through the eyelets.  I tried to yank out the
engine with all my strength and couldn't.  I think it's strong enough.
(Unless some ejection charges put out as much as a hundred pound of
force that is ... ).

This may not be enough for H engines or better, but since I haven't
certified yet on them, the point is pretty moot. :-)

Note:  I've never been a big fan of short and stubby rockets before,
but after assembling the Onyx, I think I'm beginning to like em.  I'm
just dying for the winter to go away so I can try it. :-)    LOC
mentions that you can launch the thing on a D engine.  I don't know
but I get the feeling that an Onyx on a "mighty" <heh> D engine will
have a pretty whimpy flight.

Now beginning to build a LOC Lil' Nuke.  This one's real cute.

--
Yves
CAR #S255

 
 
 

LOC/Onyx construction questions

Post by DG » Sun, 22 Dec 1996 04:00:00


Quote:

> Not on an Aura.

I thought we were talking about an Onyx here!

Quote:
>In fact T-nuts are designed to work the other way, and mounting
> them with the plate outwards can lead to them pulling out, even with epoxy to
> hold them in.

You're right about the design, but in my experience the backwards
retrofit works quite well when 30-minute epoxy mixed with a small amount
of glass whiskers is used to lock it in.

DG
TRA #4666 Level 2

 
 
 

LOC/Onyx construction questions

Post by Erik Benne » Mon, 23 Dec 1996 04:00:00


Quote:

> The biggest motor I ever flew in my Onyx was a G110 Blue Thunder and the
> regular epoxy fillets held fine. You probably don't need alot of
> reinforcement since it has plywood fins and is a lightweight model.

> The only time a fin ever broke off of my Onyx was when a kid that was
> chasing the recovery stepped on it.

I prefer to fly tanks when possible. I am planning a new Onxy,
this time with a 38mm motor mount. Mainly to fly long burn
H motors, but hey, I357 anyone?

I broke a fin once, the chut opened but was tangled, the fall from
4000 feet was just too much for the fin.

On the other hand, a E on an Onyx is also an interesting flight,
50ft or so :)

--

Omega Communication Systems, Inc.              
Communication Technology for the World


http://www.omega3.com

 
 
 

LOC/Onyx construction questions

Post by Yves Lacom » Tue, 24 Dec 1996 04:00:00


Quote:

>I broke a fin once, the chut opened but was tangled, the fall from
>4000 feet was just too much for the fin.
>On the other hand, a E on an Onyx is also an interesting flight,
>50ft or so :)

Is that 50 feet on a "Standard Onyx" or a "Flying fiberglassed tank
from hell Onyx" ? ;-)

--
Yves

 
 
 

LOC/Onyx construction questions

Post by Chris Jacob » Tue, 24 Dec 1996 04:00:00


Quote:


> >I broke a fin once, the chut opened but was tangled, the fall from
> >4000 feet was just too much for the fin.
> >On the other hand, a E on an Onyx is also an interesting flight,
> >50ft or so :)

> Is that 50 feet on a "Standard Onyx" or a "Flying fiberglassed tank
> from hell Onyx" ? ;-)

> --
> Yves

I have a LOC Onyx and have yet to see it go 2000 feet with a G-64 in
it.  Hmm  wonder what motor was used for 4000 feet.  At anyrate I have
flown mine on an E-30 with results in the 700 to 800 foot range
(estimated only)
I have flown in it on a windless day (make sure no wind if you try this)
with a D12-3 to around a 100 feet very very VERY slowly.  Kinda nice to
look at though.

My Onyx has flown many many times and I think it really likes a G motor
for between 1000 and 2000 feet.

 
 
 

LOC/Onyx construction questions

Post by Erik Benne » Wed, 25 Dec 1996 04:00:00


Quote:


> Is that 50 feet on a "Standard Onyx" or a "Flying fiberglassed tank
> from hell Onyx" ? ;-)

My tank, as in Panzer Tank. And this rocket is not from hell, for that
you need my 2.5" 54mm motor mount rocket. First flight will be a nice
and easy J90, but I hope to fly it with my Kosdon 2550ns K. Hmmm
K300 ( 8second burn) maybe?

Quote:

> I have a LOC Onyx and have yet to see it go 2000 feet with a G-64 in
> it.  Hmm  wonder what motor was used for 4000 feet.  At anyrate I have
> flown mine on an E-30 with results in the 700 to 800 foot range
> (estimated only)
> I have flown in it on a windless day (make sure no wind if you try this)
> with a D12-3 to around a 100 feet very very VERY slowly.  Kinda nice to
> look at though.

> My Onyx has flown many many times and I think it really likes a G motor
> for between 1000 and 2000 feet.

Well a G200 really kicks it up, but nothing does a mile like a H! I am
wanting to try a H45 or a H70, but need to build a new one for the H45.
BTY doing Hs in an Onyz is not for new fliers. The wind has to be
perfect for
recovery, and there is not much room for electronics. You have to
install the electronics in the nose cone. I should have a 38mm Onyx
ready for this summer, complete with 3 centering rings, 38mm motor tube,
electronics in the nose cone and fiberglass body and fins.

--

Omega Communication Systems, Inc.              
Communication Technology for the World


http://www.omega3.com