Arcas HV build thread

Hey guys,

This is my first build thread and im doing it on the Madcow Arcas HV. I just received it in the mail yesterday and i am quite eager to start.

Parts ready to wash



Aft mounting ring epoxied

did you prep those tubes at all?

Yeah, washed everything.

littlemisterbig said:

Yeah, washed everything.

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and sanded? What epoxy is that?

Oh crap, I didn't sand. This is the epoxy https://m.loctiteproducts.com/p/13/0/7/epxy_mrn_s/Loctite-Epoxy-Marine

You need to sand fiberglass with 60-80 grit paper if you want that epoxy to adhere.

Ummm ok what should I do?

if it hasn't cured remove the rings an remove epoxy with denatured alcohol or nail polish remover. Sand and rebond.

Sand the inside of the tube in the fin area. Next to the slots on the outside. On the MMT sand everything still exposed with 60 grit. You put epoxy on both sides of the rings. You'll have to space them away from the fin slots, or shape the fun tabs to match.

With both CRs on, do you plan to inject internal fillets, and do you have an epoxy that flows well enough to do so?

What if it already cured?

I'd leave it as is then, and make sure to get the fins in really well.

opinions on this will vary.

Does that epoxy really say 2 minutes on it? That doesn't give you any bit of work time before it starts to warm and set.

Ok thanks, I wasn't going to do the injecting, I was planning on putting the epoxy on the fin roots and then putting the fins in.

And it's not two minutes it's 150 minutes

littlemisterbig said:

Ok thanks, I wasn't going to do the injecting, I was planning on putting the epoxy on the fin roots and then putting the fins in.

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Yea, I just saw madcows instructions. Should work fine...just sand the tubes up good.

should i put the motor retainer on before or after i put the mmt in the rocket?

littlemisterbig said:

should i put the motor retainer on before or after i put the mmt in the rocket?

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doesn't matter. personally i install it last after painting. for me its easier to mask off the exposed motor tube then masking off the retainer.

littlemisterbig said:

should i put the motor retainer on before or after i put the mmt in the rocket?

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Depends. What retainer are you using? If it's an Aeropack I usually hold off so I can remove the rear CR after the MMT is installed and apply internal fillets and/or foam the fin can. If you're injecting or not doing fillets then I would put it on now to make things a little easier. NOTE: If you're using a screw on retainer (e.g. AeroPack) make sure to use JB Weld epoxy as most other epoxies do not have the heat resistance required.

littlemisterbig said:

What if it already cured?

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Knock 'em off and start over. Better to do the work to make it right... especially since this is a HPR rocket.

rocketgeek101 said:

Knock 'em off and start over. Better to do the work to make it right... especially since this is a HPR rocket.

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I'd be worried it'd cause more damage than it's worth.

Got motor retainer mounted on tube.

Did you use JB weld?

I've used 5 minute before. As long as the burn is short it should be fine. However I have no idea what the properties are of the Underwater epoxy used here.

Resists up to 400f i believe

I've used that marine epoxy, it does not harden quit as hard as others, also takes a long time to set, & even longer to fully cure. It does hold up good though.

Is this for your JR. L1 Cert?

yes it is

Good luck with your build and keep us posted on your launch!

You already know I am subscribed What did you end up doing about your forward CR? I would think it was fine as long as the fins are on good and aft CR is attached right

Thanks guys! Therell be more tomorrw!