CJ's Space Cowboy build manual.....you asked for it!

blackjack2564 said:

The standard av-bay installation is 2 rivets 180 degrees from each other.

Measure 1.5 inches from edge of tube and mark.
Install coupler to halfway mark & drill hole with 5/32 bit and install rivets.

For high performance I will use 3 stainless 2-56 cap head screws.The BP is tapped for 3 or 4 hole installation.

Place BP into coupler and slide into payload to the halfway mark.

Shine flashlight into coupler to illuminate the holes. [works better if you slide lite into coupler about 1/2inch from BP]

Mark hole, remove coupler/BP & drill hole.
Install screw to check for fit, and mark next position.
Removes screw & coupler/BP & drill 2nd hole.

Repeat for 3rd.

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Do you use any type of gasket in your Av bays ? What i mean is ,between the bulkhead and Av bay itself to protect the electronics and insides from BP blast.

Paul T

sodmeister said:

Do you use any type of gasket in your Av bays ? What i mean is ,between the bulkhead and Av bay itself to protect the electronics and insides from BP blast.

Paul T

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So far the fit of the stepped BP has been so good no gasket is needed. [one of the major advantages of having excellent CNC machining.]

Nothing I have flown has suffered any ill consequences.

sodmeister said:

Do you use any type of gasket in your Av bays ? What i mean is ,between the bulkhead and Av bay itself to protect the electronics and insides from BP blast.

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Jim is right; the majority of kits including Performance Rocketry and Wildman fiberglass kits have stepped bulkplates. When you have the two right angles in sequence you have little chance of gas entry. If, on occasion, you have a situation such as in this scratch design, where you end up with one surface/angle, a gasket can be your best friend.

I have one that's a little leaky, (non-stepped wood bulkhead) but all I do is use a little blue tape to seal it. You don't have to get fancy if you don't like to. besides, having special gaskets would just be something else for me to forget or loose.

cbrarick said:

besides, having special gaskets would just be something else for me to forget or loose.

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When I design in a gasket it is always held in place by mounting hardware so it's only lost if the rocket is lost.

Picking up where we left at post #26:

After coupler has been drilled for 3 screw attachment points for BP installation, remove everything and insert the coupler into proper position. [halfway mark]

Using same technique slide flashlight into coupler close to pre-drilled holes.
They become readily visible through airframe.

Mark & drill PILOT hole with same bit used for 2-56 screw. Insert screw and move to next position....mark....drill & insert 2nd screw. Repeat for final 3rd screw.


.

Leave 1 screw in position to assure proper alignment for final step.

To recess the cap head use #29 bit,.135 diam.[1/8 will work, .125 diam. a tad tight, ream a bit] and carefully center on pilot hole.
Drill through the airframe and just barely into coupler to recess cap head flush with airframe. Just drilling through airframe will leave head above the surface.

Finesse must be used to get this right & drilling..... test fit screw.... drilling a bit more... test fit is advisable rather than trying to accomplish the task all at once. When screw is flush, leave in position & repeat for 2nd hole. At final 3rd hole, remove the screw left in for alignment purpose and repeat above to flush this last screw.


Some of you have drill presses, machining equipment on hand, & knowledge of such. This is written for those of us with simple hand tools that want to get similar results. A little patience and following these steps will get you there.

As you can see.... mission accomplished, screw are perfectly flush.

very nice, gonna try that

pshooter26 said:

very nice, gonna try that

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Thank you.

First time I did this I used math and formula's to devise a Wrap with the screw positions marked on it. A bit complicated and did not take into account the slight variances that come with the tubes batch to batch. Worked great for the first tube, but was off a tad on the second one I did Month later.

I came up with this unscientific caveman version & it's simplicity at it's finest!

The best part is anyone can do it with ease.

Shear pins for NC:

Use 2 # 2-56 nylon shear pins/screws.

Mounted opposite from each other. [180 degrees apart]

Measure 1.5 inch from front end of payload.
Insert NC & drill hole, insert pin and drill & mount 2nd. Use # 47 bit or 5/64 same used for BP plates.
Leaving the first in assures perfect alignment for second.

Use same bit & drill partially into NC/payload joint for key-mark to aid in alignment during flight prep. This only needs to be deep enough to see through a few layers of paint.

I realize there are other solutions for alignment, this is our tried and true method.

Drilling vent hole in fincan is not a cut & dry procedure.Location should depend on flying stlye. If you never intend on flying the maximum size motor due to range waiver, vent should be placed between top of largest motor intended to be flown and bottom of Av-bay when in the fincan.

For largest motor I will use:

Lay out av-bay & motor case [or measure] next to fincan and locate where vent should go..drill hole. Larger the volume = larger hole. From 1/16 to 1/8 will suffice. I used a 7/64 in. This size has been flight tested & it works for many size motors.
Same size [7/64] for payload in center of tube. This takes into account the hole being partially blocked with chute/shockcord.

Yes I know there are calculators for this that may show a different size, but why argue with success?:wink:

BlackJack,
You do nice work.

For maximum performance rocket must be flown out of a tower. Once again, this may be flown where waiver prevents this criteria.

For those railbuttons are one method being used & they may be removed if tower launching is available.

Position for these should be near rear of fincan [approx. 1/2in.] and 1-2 inches in front of fin. 1/8 bit and letting the screw self tap will net a sturdy mount. Grinding/cutting off the screw to fit flush with interior of airframe must be done.


Next up electronics sled.

blackjack2564 said:

David Reese ran tons of specialized computer sims on the thickness, shape and taper over a wide variety of motors to come up with this optimized design.

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To fill in the details a little more on this, CJ gave me the rough shape of the fin planform back at Indiana Rocketry's Thunderstruck launch last year, and asked me to work out an airfoil planform with my genetic algorithm that interfaces with Missile DATCOM. Maintaining the same outside shape (for looks) and keeping an eye on structural limitations, I ran the algorithm over the transonic Mach number range to generate the airfoil planform, with minimum mean Cd as the objective function. The final result was translated to a DXF and shipped off to Eric @ BadAzz for CNC fabrication. The closed loop process from simulator to part kept the tolerances tight and the aerodynamics sharp.

Sweet job on fin calcs too!! I Love this Rocket!!!

Eric1 said:

Sweet job on fin calcs too!! I Love this Rocket!!!

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As well you should, couldn't have done it with out ya buddy!:dark:

blackjack2564 said:

For maximum performance rocket must be flown out of a tower. Once again, this may be flown where waiver prevents this criteria.

For those railbuttons are one method being used & they may be removed if tower launching is available.

Position for these should be near rear of fincan [approx. 1/2in.] and 1-2 inches in front of fin. 1/8 bit and letting the screw self tap will net a sturdy mount. Grinding/cutting off the screw to fit flush with interior of airframe must be done.


Next up electronics sled.

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I assume that is a CTI 54 mm tapered aft closure. Could you post a close-up of it? Are those still available, or a one-off item?

MarkH said:

I assume that is a CTI 54 mm tapered aft closure. Could you post a close-up of it? Are those still available, or a one-off item?

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Should still be available..Call Tim at Wildman I think he still has some- not listed on his site..

MarkH said:

I assume that is a CTI 54 mm tapered aft closure. Could you post a close-up of it? Are those still available, or a one-off item?

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Yes they are currently available. Wildman has them, though not shown on website, Call for one. They were same price as the regular closure...40.00 last I knew.

Here is the SpaceCowboy in living color. Clear still wet so I can't move it. Better pictures later. Rustoleum Metallic blue and metallic silver with Florescent red/orange accents. Many multiple coats of clear.

How long the vinyl [or paint for that matter]will stay on is the big question, hence the reason for clear coat over it. Mach 2 + speeds tend to rip off vinyl and melt paint. It looks good for the press pics & I have high temp undercoat if needed.

Ps No reflection on quality of the vinyl..... nothing stays on when you are going fast enough.... burnt paint....badge of honor.Lol

Time to go space trucking. Beautiful build.

blackjack2564 said:

Yes they are currently available. Wildman has them, though not shown on website, Call for one. They were same price as the regular closure...40.00 last I knew.

Here is the SpaceCowboy in living color. Clear still wet so I can't move it. Better pictures later. Rustoleum Metallic blue and metallic silver with Florescent red/orange accents. Many multiple coats of clear.

How long the vinyl [or paint for that matter]will stay on is the big question, hence the reason for clear coat over it. Mach 2 + speeds tend to rip off vinyl and melt paint. It looks good for the press pics & I have high temp undercoat if needed.

Ps No reflection on quality of the vinyl..... nothing stays on when you are going fast enough.... burnt paint....badge of honor.Lol

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Wow that is a beauty, a darn fast beauty