What did you do rocket wise today?

[spiker04]

Why is the shock cord external? Yes, what you describe sounds much more secure than a hole in a fin, but why not one of the many internal connection methods?

Yes ...good question ?

 

[Sooner Boomer]

Why is the shock cord external? Yes, what you describe sounds much more secure than a hole in a fin, but why not one of the many internal connection methods?

Possibly to try to avoid breaking a fin off with a conventional recovery (coming down fins-first). I've heard this called a "squid line" method.

 

[dhbarr]

Why is the shock cord external? Yes, what you describe sounds much more secure than a hole in a fin, but why not one of the many internal connection methods?

When I've got fragile fins, this is an easy way to bring it down sideways.

 

[kuririn]

Why is the shock cord external? Yes, what you describe sounds much more secure than a hole in a fin, but why not one of the many internal connection methods?

When I've got fragile fins, this is an easy way to bring it down sideways.

The Astron Cobra was available as a Design of the Month plan and as a kit.
The old DOM instructions do not give a reason for the external static line and hole in the fin.
The kit instructions give two methods of shock cord attachment. Method A is the static line and hole in the fin. It says that this "lowers the main body of the rocket nose first, reducing the possibility of fin damage at landing".
Method B was the old two slits in the body tube method.
Don't see any problem with the kevlar loop under the rear rail button method. The rear rail button will sit a hair higher than the front button due to the kevlar cord, but I don't think it will matter. If you're OCD then you might want to put a thin shim under the front button. Also make sure there's no slack in the static line when you install the transition.
I built a clone and launched recently. Only mods were a tri fold mount and clear payload tube. It successfully launched with all three motors igniting and landed with no damage.

 

[DigBaddy]

Ordered a Minie Mag.

 

[MidOH]

Can you confirm that the mini mag is still ''Loc N Fin'' construction?

I don't have a 5.5" fin guide.

 

[jmasterj]

Can you confirm that the mini mag is still ''Loc N Fin'' construction?

I don't have a 5.5" fin guide.

Why would it not be? It's still advertised as such.

Mine bought late last year has that feature.

 

[DigBaddy]

Can you confirm that the mini mag is still ''Loc N Fin'' construction?

I don't have a 5.5" fin guide.

Once it shows up I can.

 

[rharshberger]

Can you confirm that the mini mag is still ''Loc N Fin'' construction?

I don't have a 5.5" fin guide.

Make a payloadbay.com fin guide, print it on paper, glue it to a sheet of Dollar Store foamcore board, cut it out with an exacto and done. I have used them on up to 7.5" and 5 fins.

 

[prfesser]

Why is the shock cord external? Yes, what you describe sounds much more secure than a hole in a fin, but why not one of the many internal connection methods?

With three 18 mm motors it's a fairly heavy rocket, and the fins are rather long. Having it land upside down should avoid breaking off a fin.

 

[jqavins]

The rear rail button will sit a hair higher than the front button due to the kevlar cord...

Not if you put an appropriate spacer under the forward button, like a washer or a loop of the same kevlar cord. If you care.

 

[kuririn]

Not if you put an appropriate spacer under the forward button, like a washer or a loop of the same kevlar cord. If you care.

Or a shim?

If you're OCD then you might want to put a thin shim under the front button.

 

[Cape Byron]

I don't know whether to or . Did you get it down? Will you get it down?

It’s been through the equivalent of two years rainfall.

Just not a priority anymore, even if it was pristine.

 

[jqavins]

Or a shim?

Admit it, you went and edited that in after I posted, didn't you. I couldn't have had a brain fart that big. You have to have edited it. ADMIT IT!

 

[kuririn]

Admit it, you went and edited that in after I posted, didn't you. I couldn't have had a brain fart that big. You have to have edited it. ADMIT IT!

You know that I would never do that to you, buds.
But still enjoying your comments and repartee.
Just wondering when you're gonna post on what YOU did today that was rocketry related?

 

[boatgeek]

You know that I would never do that to you, buds.
But still enjoying your comments and repartee.
Just wondering when you're gonna post on what YOU did today that was rocketry related?

Give the man a break, he's been busy.


And in a pre-emptive defense against that question, I reviewed a prospective Junior L1's OpenRocket file today.

 

[Wayco]

Started cleaning the rockets we flew last weekend with UROC and prepping them for this weekends launch with SLVR. Here is a picture of the temporary headquarters for the "Wayne and Sharon show":

 

[MidOH]

Why would it not be? It's still advertised as such.

Mine bought late last year has that feature.

I think all the 4" and 5.5" models are that way. The 7" models had some weird issues.

My 5.5" Goblin was Estes easy, to build. Maybe even easier. With the center centering ring sanded to be kinda loose on the motor tube, the fins self alighn.

 

[jmasterj]

I think all the 4" and 5.5" models are that way. The 7" models had some weird issues.

My 5.5" Goblin was Estes easy, to build. Maybe even easier. With the center centering ring sanded to be kinda loose on the motor tube, the fins self alighn.

Yes, a bunch of the 7.5" kits have the MMAS, but since that has a 5.5" mother tube it only works in that biggest size.

 

[bad_idea]

Had a plywood centering ring crack as I was drilling it to take tiny u-bolts repurposed from wire rope clamps. Started fiberglass repair of the ring yesterday. Was going to complete the repairs tonight, but ended up occupied otherwise. Maybe tomorrow.

This ring was custom laser cut, but it never occurred to me to include these holes in the CAD file. Which is rather odd, considering I remembered to have vent holes burned in the bottom two rings. Oh well, lesson learned, both on drilling thin plywood and on not having the laser do the work for me.

 

[rbelknap]

Got the fin can masked and the fins painted after work today. I pulled the tape a little while ago:


(Finger for scale?)

I love me some clean lines.


Edit: I also realized I have a small problem with my order of operations. Body tube is also painted glossy white. This may cause issues with epoxy adhesion to the BT… I guess I’ll be sanding some of that paint away so the epoxy can bond with the paper underneath.

AND I’m going to the the BT stick out about ⅜ of an inch from the bottom. “But epoxy mess” I hear you say. I’ll hade any with a wrap of aluminum tape. (Reminiscent of the aluminum nozzle on the “original”)

 

[dhbarr]

Got a dozen 3/8 x 1in bolts and nuts, as well as four heavy furniture levelers. Rescuing an old steel frame table to make a rocketry work surface for the boys.

 

[GrouchoDuke]

Epoxied another nosecone ejection harness retainer. Made an ejection harness. Tweaked the packing plan. Ejection tests. Sanded nosecones & fin joints. Drilled shear pin holes. Fought with high temp paint. Worked on a rocket tracking iPhone app.

 

[Astronaut Cheeseball]

Paint done on the SA-14 Archer. Dry time a week before decals and clear coats.

 

[jqavins]

Just wondering when you're gonna post on what YOU did today that was rocketry related?

Bit of a depressing point. Lately I can hardly get up off the couch. All I do rocketwise is hang out here. But I will be attending NYPOWER this weekend, and hope to have some launches to report during and after. Maybe that'll get the juices flowing and get me back to some projects.

 

[bad_idea]

Bit of a depressing point. Lately I can hardly get up off the couch. All I do rocketwise is hang out here. But I will be attending NYPOWER this weekend, and hope to have some launches to report during and after. Maybe that'll get the juices flowing and get me back to some projects.

Hope you feel better soon. Rocketry is a good tonic for many things.

 

[HoldYourOwn]

Finished up the final touches to my wife's Barbie themed 7.5" stretched Loc Doorknob!!

 

[BigMacDaddy]

I went and picked up some big tubes that someone told me they saw out for recycle. I also saw something out of the corner of my eye while driving home that I had to go back and check out. I missed the chance to buy these 4' tall Pringles packs when they were for sale at BJ's. Sadly this one was water damaged. However, I did get to check it out and it would make a great low-powered or mid-powered rocket. Nice light tube! I will keep looking and hope that BJs sells these again!

 

[jd2cylman]

Hey @hobie1dog , I see some fella is selling 7 Launch Pad kits on FB. Should I reserve them for you?

 

[jd2cylman]

On a more serious note, (last night, actually) I prepped the AV bay for my WM AAD98 Interceptor. Then I built a 75/2560 K560W for my WM 5" Goblin, and made sure all the parts fit my 75/3500 EX case. So, I'm more or less ready for mini Midwest Power...