My First Public Build :-)

[bobby_hamill]

Ok after some prodding I have started my 4 Fin Black Brant 2 builds .
There will be 4 builds at the same time all 4 are of the same build the difference is the payload sections and the airframe will have 2 paint patterns
2 of the sections will be the normal Black Brant Payload that has no parachute recovery section.
The other 2 sections will have a longer payload section as a parachute recovery section was added to the payload.

The airframe is a Estes BT55 with a motor mount of a BT50
the 4 fins are laser cut from 1/16 Burch Plywood. as well as the fin alignment guide. ( thank you Carl Campbell at DFR Technologies )

Attached are the 4 versions I intend to build and fin measurements

Hope you enjoy the build as I progress with it

Bobby

 

[bobby_hamill]

Here is the differences in the 2 types of Black Brant Payloads I will be modeling

 

[bobby_hamill]

Cut a BT50 tube to 9 inches long insert engine block and "D" size engine hook
Note engine hook can be omitted if you want to use friction fit motor retainer

 

[bobby_hamill]

Here is a photo of the 3 laser cut fin alignment guides ( Thanks Carl )
I marked the front on all 3 and at the bottom to keep all 3 guides aligned the same way

 

[bobby_hamill]

Here are the fin guides in use . I glue the 2 top fins on first then after the glue sets I roll the
guide by 180 degrees . The rear centering ring is glued flush with the end of the BT50 tube.
When installing the fins I butt the rear edge of the fin up against the front face of the centering ring

NOTE !! Do not glue any more centering rings on the BT50 tube until later in the build .
The 1 rear centering ring is all that is needed at this time.

I thought I had some crazy glue on hand but did not .
So got to hit the local store to get more

 

[bobby_hamill]

Ok got the super glue and got the fins tacked on to the BT50 tube
Stay far away from the alignment guides so you wont glue them to the BT50 tube
If you are going to build only 1 rocket you can use 2 of the fin alignment guide as a holder
to hold the BT50 level and apply epoxy to the fin tube joint

I will be applying some gauze with epoxy over the top of the gauze to
hold the engine hook in place

In my case I have 3 more like this to build and once I have all 4 built
I can apply epoxy to 1 section on all 4 at the same time

Also I will be applying a very thin layer of super glue around the bottom edge
of the BT50 centering ring to prevent the inside edge of the BT50 tube
from fraying up and making the "D" engine hard to insert

 

[bobby_hamill]

did 3 more BT50 tubes with engine block, engine hook and 1 centering ring

 

[bobby_hamill]

Fin attachment for part 2

 

[bobby_hamill]

2 completed and 2 to go

 

[qquake2k]

Looks like some fun builds. But I'm curious, why did you post this in high power rocketry?

 

[K'Tesh]

Looking good! I'm going to keep an eye on this thread... op:

 

[bobby_hamill]

qquake2k

I see your point now . At the time I was thinking high power but "D"s are low power
Maybe the moderator can move this build over to the scratch build section ?

Bobby

Looks like some fun builds. But I'm curious, why did you post this in high power rocketry?

 

[bobby_hamill]

Moderator

Could you please move this build over to the scratch build section ?

Thanks !

 

[qquake2k]

There is also a scratch build forum.

 

[bobby_hamill]

qquake2k

I don't know where to call this a scratch build or a kit bash ?
As the first build I did of this model I used an Estes Black Brant kit with the 3 fins
and I have never posted a build on the forum before.

It might be more of a scratch build / sport scale ?

 

[bobby_hamill]

Well I finished adding the fins to all 4 of the BT50 tubes and I glued the second
centering ring on so it butts up to the fins. Tomorrow I will add the 3rd centering ring
and shock chord attachment point

Note !
when you cut a tube orientate the uncut end to be the end where the motor is inserted.
and the cut end where the motor ejection goes through. This will allow the motor to be inserted
with less problems of frayed edges.

 

[K'Tesh]

Note ! when you cut a tube orientate the uncut end to be the end where the motor is inserted.
and the cut end where the motor ejection goes through. This will allow the motor to be inserted
with less problems of frayed edges.

Or apply a thin coat of super thin CA to seal it, then sand it smooth.

 

[qquake2k]

Note !
when you cut a tube orientate the uncut end to be the end where the motor is inserted.
and the cut end where the motor ejection goes through. This will allow the motor to be inserted
with less problems of frayed edges.

How did you cut the tubes?

 

[bobby_hamill]

Estes body tube cutting guides
They does a good job to.

How did you cut the tubes?

 

[farsidius]

What's better than a Black Brant? Four Black Brants! Following your build.
Four at once is impressive - can't wait to see how they all turn out. Thanks for sharing your build here!

-brant (not a rocket)

 

[bobby_hamill]

Ok
New installments on the build
my original intention was to use some long Kevlar ( apogee #30326 or 300# cord )
But I started to worry about the Kevlar zippering the airframe even it it was flame proof.

So here is what I came up with i used a 19" peace of Kevlar and tied the 2 ends together
looped it over the BT50 tube twisted the loop about 2 times and slid a centering ring over the Kevlar

NO GLUE YET !!

You might want to practice on a scrap to get the hang of getting the centering ring over the BT50 and doubled Kevlar

 

[bobby_hamill]

Now on to the second part
the idea is to get the Kevlar loop about 1-2 inches below the BT55 airframe
This will prevent a zipper and give you enough of a loop to thread a shock cord to the Kevlar.
Only the shock chord will be rubbing the edge of the BT55 airframe

If the Kevlar looks like it will be to long and will hang out past the BT55 airframe edge you can slide
the centering ring back away from the edge of the BT50 engine tube

That is what happened to me , the first cord I cut to 19 inches which came out ok.
So I tried a 21 inch section which was to long resulting in the Kevlar being past the edge
of the BT55 after parachute deployment

I made sure that the knot would be on the opposite side of the engine hook to balance things out

 

[bobby_hamill]

Once you get everything aligned and positioned just right you can apply a very small amount of elmers white glue to hold the centering ring in place
take about 2 drops of super glue and place it on the knot and press down on the knot with your fingernail and hold to the super glue sets .
Gently roll your finger from side to side and the super glue will release your fingernail

A better way to press the knot down is with wax paper the super glue wont grab to the wax paper

When I get the other 2 BT50 tubes done like the 2 I just did We will be ready for epoxy

Bobby

 

[bobby_hamill]

All 4 BT50 motor tubes done .
Sunday I will start with the epoxy

Bobby

 

[bobby_hamill]

Well I started on applying the epoxy to the fins and wanted to try a new process of
loading the epoxy by a syringe but wanted to have a short section of clear tubing attached to the syringe.
The clear tubing would allow me to suck up the epoxy into the clear tubing but not all the way into the syringe.
This way I could reuse the syringe and just throw away the short length of tube and the needle .

I uses a 16 gauge BLUNT tipped needle inserted in the clear tubing . You can see where I inserted a pair of
needle nose pliers into the end of the tube and opened the pliers to expand the tubing. When you expand the tubing
quickly insert the cut off base of the needle and the tubing will shrink back to its original size sealing the needle base in place .

Well I found out that I need a needle way bigger than 16 gauge as the epoxy was to thick for the syringe to suck up the epoxy in the tube
The way this is supposed to work is the syringe sucks up the epoxy into the tube but NOT into the syringe allowing reuse of the syringe
Plus I should have tested this procedure out on scrap first .

 

[bobby_hamill]

So with the syringe process out of the way I used the small Popsicle stick method and applied the epoxy to 1 side of all 4 of the BT50 engine tubes.
Now to let the epoxy dry and do the 2nd side tomorrow afternoon

Bobby

 

[bobby_hamill]

Side 2 before and after epoxy on all 4 BT50 engine tubes
2 down and 2 left to go

 

[bobby_hamill]

Side 3 done 1 more side to glue on the BT50 engine tube
the fun really starts !

Bobby

 

[bobby_hamill]

well finally finished with the BT50 engine tube and gluing the engine hook in place
Gonna take a break Thursday and start back on Friday with slotting the BT55 tube for the
fins to fit in .

Take note of the small Popsicle stick I used to apply fillets to the fins. The end of the stick was cut
at a angle to allow for a thinner fin fillet

Bobby

 

[bobby_hamill]

Work started on the BT55 airframe
4 fin tube marking guides printed and applied pic 26
pic 27 marking guides are taped down temporarily to prevent guides from moving