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Gas Gas Gas: I'm gonna run as a flash!

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Zertyme

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Gas Gas Gas: I'm gonna run as a flash!

The goal is to fly it on the H999 and the I1299.
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Most of the parts come from a Darkstar Mini I got from https://eurospacetechnology.eu/index.php.
I will be using: the body tube with the slotted section removed, the nosecone, fins as stock to make the bulkheads, shock cord, and parachute.

The part between the end of the casing and the nosecone shoulder will be supported by a piece of fiberglass coupler as a sanity check.

Motor retention: threaded Aerotech closure + bulkhead on the stiffening coupler.

Fins: 2.4mm unidirectional carbon fiber plates, bonded with DP490, tip-to-tip TBD.

Electronics: Stratologger CF or AltimaxSimply 2018, tracking using an Eggfinder Mini. I also want to add a small camera such as a Runcam split3 or split4.

Ejection: surgical tubing zip-tied to the bulkhead, this is to prevent the ejection charge from being disabled during the acceleration.


Some of the parts layed down. I need a longer section of coupler :/
1610926276337.png


Because I also want to "test" the rocket on smaller 29mm motors. I made an adapter using the centerings rings and MMT provided in the kit:
1610926404041.png

Still missing the thrust plate.


To be continued.
 

Zertyme

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Recovery fits!

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This should leave enough space for the ejection charge, line cutter (or hot wire cutter), and the end of the forward closure.


______________________________


On a side note, I would like to make an interest check.
I've been thinking about manufacturing a limited run of kit, similar to Gas Gas Gas, and I would like to know if people would be interested before possibly making parts.

Specs:
-Custom 5.5:1 VK fiberglass nosecone.
-Roll wrapped 38mm, 370mm thin wall fiberglass airframe, translucent purple.
-3mm G10 fins.
-3m of 3mm Technora T12 shock cord.
-15" lightweight chute
-3d printed alignment jig
-3M DP490, enough for the fillets.

Should fly perfectly on motors up to Cti 3G and Aerotech 38/480, down to 24mm motors with an adapter. (Cti 4G would be possible but without much volume left for recovery)
Nosecone and body tube would be made by me.

Keep in mind that this is just an interest check: might happen, or not.
If you are interested, let me know.
 

Neutron95

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I would love a kit like that. The purple body tube sounds pretty neat. I might have to steal the idea for some of my designs.
 

Zertyme

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Fins are made from 2mm carbon fiber plates that I had on hand. Cut using a hacksaw then finished and beveled on the belt sander.
This was my first time using DP490 for fillets. It's just perfect for fillets, non-sag, good mechanical properties, etc...

I used the mixing nozzles to first dispense an equal amount of resin for all the fillets: turns out squeezing the resin out of the mixing nozzle requires quite a lot of pressure, next time I'll get the dispensing gun.

Next is the Prepreg tip-to-tip...
 

Zertyme

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3 layers of 150g/m² UD carbon. Root chord thickness of 3mm and tip chord thickness of 2.15mm. Leading coated in DP490 just for aesthetics (to be sanded).
Booster section weight before tip to tip: 130g
After: 140g


Wildman nosecone is nice but too heavy: so I'm trying to mold a new one.

To be continued.
 

Zertyme

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Not the finest mold. The Epoxy/fumed silica mixture I used is quite brittle, thus I had to fill some of the areas with filler (dark section). Next time I'm getting a proper gel coat.
The layup was 2 layers of 160g/m² twill as sanding layer/finish, followed by 5 layers of 171g/m² S2-glass.

IMG_20210219_010606.jpg


IMG_20210219_015238.jpg


To apply compression I used a long ballon. Vacuum bagging was too tricky for such a small diameter and I didn't want to spend as much time and resources on a bladder. (I would have to redo the mold).
IMG_20210219_114930.jpg


Shoulder/cone transition will need sanding and filling. Guess what else needs a lot of sanding, the cone.
Turns out it's a bit oval. I think this is due to the deformation of the mold while the balloon applies pressure on the layup.

IMG_20210219_121854.jpg


The tip was chopped off, the inside cleaned from excess resin and I installed an AL tip from a proline cone.

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The new cone is 60g.

ope
Some work was done on the fins:
IMG_20210218_220725.jpg
 

Zertyme

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I was also able to experiment with manufacturing my own carbon fiber plates. hopefully, this plate will be used on a 54mm CTI flying case fincan: "Don't Stand So Close"
The layup is nearly balanced and quasi-isometric.

3[90/0/+45/-45]s with a 90 plie as midplane

Post Debulk midway through the layup. This should have been done every 4-5 plies. this was a cold debulk, warm debulk would have been preferable.
1613812475701.png


Final ply
IMG_20210217_170223.jpg

It was covered in Vacuoplex MP. Because of the microporous release film, it keeps all the resin in, but let the gases vent, right?
Well yes, unless the resin finds another path:

IMG_20210217_200605.jpg


This picture still sparks pain in me.
The resin found its way around the Vacuoplex. I think this is due to the fact that the tool side peel ply edge was way too close to the edge of the Vacuoplex.

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Tool side, flat, not twist.

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Bag side, a bit of waviness. (grey marks are due to the jigsaw).

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Nice and tight.

205 x 148 x 3.4mm, 157g. 1.53 g/m3, ~70/30 fiber to resin ratio.
Datasheet density is 1.81g/cm3 and 36% resin content.
Cured at 150°C

Things to change:
-Use a caul plate.
-perhaps switch to the good old peel ply/ non perf film / breather instead of Vacuoplex
-make sure the tool side peel ply doesn't extend too far.

Perhaps I should make a separated build thread for "Don't Stand So Close"
 

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