Level 3 MadCow Super DX3: No Fiberglass, No Carbon Fiber, no sweat ... ?

Very interesting build so far and wonderful job with the homemade ply wood. I don't think those will go anywhere.
The epoxy soaking through is a good thing. It shows that it penetrated well.

Another way to reinforce the tube would be with thin plywood rings. Like a centering ring, but with an ID of 3.5in or something.

op:

Alex

This is a very interesting thread and that was an awesome YouTube video. Makes me want to do my L3 on an all paper min dia. Hmmm, maybe I will next summer out at Blackrock.

I don't think you will have any problem with a competently built all cardboard rocket on an M, however when you start talking about leaving the motor tube and centering rings hanging out, I think you may be asking for problems.

Aksrockets said:

Read through this thread:
https://www.rocketryforum.com/showt...sible-LOC-Magnum-quot-Price-of-Admission-quot
A 5in rocket with a M650 did not end well.

Alex

Click to expand...

Alex,

FerdBerful is well aware of this build and this flight. He saw the rocket while I was building it, witnessed its flights from the ground, helped me pick the pieces after the M flight and then rode in my van back to Sunnyvale.

Re: "shattering" paper tubes and couplers-all-the-way-down: the failure point on my Magnum M flight is fin flutter. You may note that paper holds fine until the Magnum starts losing fins, and yellow glue holds even after that. Not a single wood joint failed on that flight.

Looking forward to the build!

Ari.

FerdBerful said:

RE: how to attach the body tube

I have a 36" motor tube. My plan is to only have (say) 24" exposed with 12" inside the airframe tube. My plan is to use 8" couplers
epoxied inside the full length of the body tube so the centering rings/reinforcing struts would be inside this double layer.

RE: L3CC/TAP not there yet. My plan is to fly it starting with a J or K and if all goes well eventually a full L. If that is successful, it's a tiny
jump to a baby M and level3 .

Click to expand...

Doesn't work that way, Ferd. You can build it, and fly it on all the motors that will lift it...

But to use it for an L3 certification, you must have the build approved by your TAP/L3CC before you mix the first cup of epoxy, or, in this case, lay down that first line of Elmer's.

Please go to the website and read the requirements for L3 certification. It explains what is required of the cert candidate, and the L3CC rep.

Exactly how thick are those fins? From the photos they appear to be .50" or more.:y:

Binder Design said:

Exactly how thick are those fins? From the photos they appear to be .50" or more.:y:

Click to expand...

He made a 5/16" thick board of plywood out of five 1/16" walnut veneer pieces.
Then, he doubled it all up to a final thickness of 5/8". I kept telling him not to make them so thick, but that just made him want to do it even more!

tuxxi said:

Then, he doubled it all up to a final thickness of 5/8".

Click to expand...

Wooly carp!!!

cherokeej said:

Doesn't work that way, Ferd. You can build it, and fly it on all the motors that will lift it...

But to use it for an L3 certification, you must have the build approved by your TAP/L3CC before you mix the first cup of epoxy, or, in this case, lay down that first line of Elmer's.

Please go to the website and read the requirements for L3 certification. It explains what is required of the cert candidate, and the L3CC rep.

Click to expand...

Yea, I finally got that. ("Gez, you can't tell some people nothing" .

I'm sort'a on the fence now about using this as a level 3 cert rocket.

If this rocket works with a big L, seems likely it would work for a "baby" M too. If I'm itching to fly it on an M, I can
always build a "big dumb L3 rocket" made with (say) 12" (cardboard-sh) concrete forms for both body and tube fins to
create a "slam dunk" L3 cert rocket. *

(* Saw one in "Rockets"(?) magazine sometime in the last year or so(?))

Peter "Holy, crap! I just realize he's going to be able to fly that crazy thing without any adult supervision" Hackett

Peter, you may want to talk to Dave R who is our local L3CC rep before you do any more work on this project (as far as I can tell, you haven't started building it yet--all you've done is made some plywood). Dave is a very helpful person and an outstanding rocketeer.

While there are some unwritten rules many L3CC members follow, some rules that are on the books appear to have laxer enforcement. A lot is up to an individual L3CC member, and I encourage you again to consult with Dave if you haven't already.

On the other hand, Tripoli has a different set of rules, and few TAPs seem to enforce rules for the sake of enforcing rules. TRA rules require two TAPs to witness a flight, but AFAICT TRA has no requirement for prior approval (though it's still a good idea to consult a TAP ahead of time). Tony Alcocer (tfish here) is a local TAP as is Tom Rouse of RouseTech casings.

Ari.

Through some sort of miracle, I'm actually close to ready to start epoxying parts together.

Some pics of various parts:
(click on them to see details)

The fins are complete:


Another view:


I epoxied a solid oak strip to the leading edges for aesthetic and perhaps
structural reasons.

Through a change in the sound the surface of the fins made when I ran my
fingers over them, I discovered a couple of voids in my homemade walnut
plywood. I drilled small holes and squeezed in gap-filling super-glue.



It's been (burrrr) cold in my rocket lair (garage) lately and it was taking
days and weeks for the super-glue to cure, so I bought a 250 watt chicken
brooding lamp and built a hot box lined with aluminum foil:



The super-glue cures much faster in the hot box. The dark walnut fins get almost too hot
to touch after being in the box for a while.

This picture doesn't show it as well as I'd like, but at night, the lair has an
cool red glow when I'm curing:



I've made a butt-load of centering rings:



The ring on the left has the 12 machine screw inserts for the AeroPack 75mm
motor retainer. The middle rings are made of my walnut plywood and the ones
on the right are made from 1/4 " 10 ply plywood. (I made the 1/4" plywood
by epoxying two sheets of 1/8" 5 ply (normal, store bought) birch plywood.

The far left shows a different view of the fins highlighting the solid oak leading
edges.

A close-up view:



I made a bunch of rings that fit inside the MadCow couplers:



I bought a bunch of MadCow 4" payload section kits for the bulkheads and
couplers. This seemed to be the cheapest, easiest way to go.

I used a "fly-cutter" to cut out the center of the payload bulkheads. I
scratched my head for a while on how to hold the bulkheads steady while
they were being cut. I came up with this set-up on my drill press:



I cut out a hole slightly larger than the 75mm motor mount tube in some scrap
plywood. I used this to hold the MadCow coupler bulkhead down. It was a
challenge to position the bulkhead so that the fly-cutters pilot drill bit was
exactly over the bulkhead's eye-bolt hole. You can see one of the thin wood
strips I used to push the bulkhead around to get it just so.

I made the ~ 12" x 24" "clamping board" with the aluminum C-channels by
gluing together 2 3/4" pieces of plywood I had laying around. The picture
doesn't show it, but there are also two C-channels on the other side of the
board to clamp the board to the drill press's steel table.

Another view:


The orange tape with the arrows on it was added after I installed the cutter
backward while changing it from cutting outside a circle to cutting inside a
circle. (The cutter can be oriented four ways. Only two of them are right)

I need to take a break. More later.

qquake2k said:

"If it's worth doing, it's worth over doing!"

Click to expand...

Damn straight!

iter said:

Peter, you may want to talk to Dave R who is our local L3CC rep before you do any more work on this project ...
Ari.

Click to expand...

Yea. Like I said, I'm on the fence wrt L3. I talk to Dave briefly and I've
printed out all the NAR and Tripoli Level 3 documents and I've been reading
them and "pondering" while chomping on my breakfast cereal, etc.

Fly-Cutter action shot!:



I've also made some centering ring-lets (1/3 of a centering ring):



Another view:



I'm going to use these ring-lets between the fins (in-lieu of though-wall
construction.) There will also be vertical plywood pieces between the
ring-lets to brace them in turn.

Why two different types of wood? You ask (perhaps.)

Well, I only have so much walnut plywood and it wasn't exactly cheep
to make, so I'm squeezing those lemons into lemonade. I'm looking forward
to laying out the different materials in an atheistically pleasing configuration.
Stay tuned

And now for something completely different:

While cleaning up my rocket lair (garage) in preparation for moving my computers
in, I found this interesting sawdust strata exposed while vacuuming under
the table saw:



I think it's: plywood, then pine or fir, followed by a mix containing walnut, then
more pine, and a topping of aluminum.

FerdBerful said:

The fins are complete:
Another view:
View attachment 158350

Click to expand...

How much do those fins weigh?

dixontj93060 said:

How much do those fins weigh?

Click to expand...

about 9oz each

Great work!

I think I'll put off going for a L3 attempt for now.

If I can get Leapy McWonder Woody to fly successfully on a L1420R (4610NS)
or (perhaps even) a L2200G (5104NS) (after working my way up from (say) a J800T)
I'll be ready to go for L3.

I've started epoxying parts together. (Yey!)

In this pic, the motor retainer has been attached and
I'm just about to add the first fin:



The "pins" in the motor retainer ring are #6 machine screws
that I greased up with (rocket motor) grease to make sure
I don't get any adhesive in the machine screw inserts.
(Works great, by the way)

Here's a pic with the fin being steadied while the epoxy
cures.



I haven't had to brace fins while attaching them since the
1970's (Probably Grumpy Dog II. The last rocket I built as a kid.
(it's on the web (!) if you're interested:
https://plans.rocketshoppe.com/narts/SP101_GrumpyDog.pdf))

It turns out the the bracing wasn't really required. The fins are
5/8" thick, and I sanded the motor tube to allow better bonding
and it was flat(ish). I ended up using the braces as guards
against disaster. I placed them ~ 1/16" away from the fin surface.

Look the Goodrich Blimp:

I tried again to get a good hot box illuminated rocket lair pic. This one's
better with exposure setting, but it's blurry. (I don't know how to
de-automatic-ize my camera. So I bested it by moving where I
was pointing and taking the pic before it could catch up.)



Back to the build:

After all three fins were attached:



I'm using Aeropoxy which Aidan says is "the best thing since sliced
bread", and I'm not disputing that. However, my experience so far is that it *really*
doesn't like to cure when it's cold. (It's been 59F (burr) in the lair.) And when
I mix it up when it's this cold, it has a consistence of ... ah ... well ... ah ... - taffy
I guess. Very viscous and sticky. So anyway ...

When I put it under my heat lamp, it slowly "melts" and goes from milky (taffy,
remember) to clear and vaguely runny. So when I attached the birch
centering ring to the front of the fins, I had to get creative:



I wanted the ring to be horizontal with the epoxy "on top" and since I pushed
the ring on from the front I had to have the rocket standing on its nose.

And no; the heat-lamp isn't wearing a tin-foil hat because it's trying to
prevent aliens from reading it's brain rays, er brain waves.

Luckily, my heat lamp is on a pulley so it wasn't *too* hard to set up.
Here's a view looking down onto the centering ring from above. (I'm on
a ladder. The things I do for you guys



After some "sand-and-try" I've got my first set of centering ring-lets
(being) attached (The Aeropoxy is curing even as we speak!):



I'm thinking it's looking pretty cool. And I haven't even added the elliptical
"X" cross members that will "triangle-ulate" for rigidness. Stay tuned: (Not the)
"Same Bat Time, same Bat Channel."

That's it (for now) and (Wow) I didn't even use up my 10 picture limit.

I started a new thread for this build. See

https://www.rocketryforum.com/showt...er-DX3-No-Fiberglass-No-Carbon-Fiber-no-sweat