The simple High Power Two Stage (Metallic Bliss)

CarVac said:

I have a hunch that finer grit sandpaper on the metal side would work even better: it's easier to remove all of the oxide layer with finer sandpaper.

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I see what you`re saying ,good point.

Paul T

CarVac said:

I have a hunch that finer grit sandpaper on the metal side would work even better: it's easier to remove all of the oxide layer with finer sandpaper.

Click to expand...

Theoretically doesn't a finer sand leave more surface area? Why do we choose to use course paper anyway.

Is it just for the mechanical bite?



I need to buy a metal polishing kit for these fins. I sanded it with 500grit and it feels extremely smooth, but doesn't look nice.

Maybe some jewelers rouge (sp?) and the polishing attachment on my dremel is all I need.

edwinshap1 said:

Same as the airframe -60 grit.

The epoxy is not removed after sanding for two purposes. It acts as a buffer to oxygen to keep the aluminum from oxidizing, and therefore losing its bonding strength, and the aluminum shavings provide a near perfect epoxy bonding thickness when pressure is applied.

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What he said.

bandman444 said:

What he said.

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Thanks Bryce.

BTW, those fins are the BOMB.....coolest thing since carbon fiber !!

Paul T

sodmeister said:

Thanks Bryce.

BTW, those fins are the BOMB.....coolest thing since carbon fiber !!

Paul T

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Thanks, got the original design from David Reese, and tweaked to get a base radius for body adhesion. After that it was just figuring out how to mill it out of a 15lb block of aluminum

edwinshap1 said:

Thanks, got the original design from David Reese, and tweaked to get a base radius for body adhesion. After that it was just figuring out how to mill it out of a 15lb block of aluminum

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Yes, I saw the thread ,very interesting ,very nice work.I love the machining proccess and the end results.

Cheers

Paul t

Would anyone be interested in a video on me putting on a entire fin?

Start to finish?

I would be interested. I guess it would involve a good amount of fast-forwarding for the curing portion?

CarVac said:

I would be interested. I guess it would involve a good amount of fast-forwarding for the curing portion?

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Or go T-fish style. Right as you finish applying the fin cut to taking off the clamps and trying to pull the fin off. I'll be open-sourcing the fin design soon, once I get the files all compacted I'll be putting up the information for the 4" body design online. Carlo, I know you can't pull the fins off the HMU 4", but would you want the airfoiled design just for laughs?

Well it's not actually airfoiled, is it? Just a diamond pattern. If you just gave me dimensions I could whip up the shape with relative ease in Solidworks with a loft and a fillet. But I wouldn't be against getting the design files.

We could potentially pull the fins off; it should be possible with the right thermal shock, if we're fast. It would probably destroy the fins, though. I've been considering it, because I think i might want to mill larger fins to up the stability margin by a caliber or so. I've grown bitterly mistrustful towards simulators of late.

edwinshap1 said:

HMU

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* HMC

Don't worry, you're not the first and won't be the last.

CCotner said:

* HMC

Don't worry, you're not the first and won't be the last.

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Dangit, I always forget.

CarVac said:

Well it's not actually airfoiled, is it? Just a diamond pattern. If you just gave me dimensions I could whip up the shape with relative ease in Solidworks with a loft and a fillet. But I wouldn't be against getting the design files.

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The shape was described to me as a biconvex diamond airfoil with a radial taper. The fin is thickest in the middle base, and tapers to 0.03" at the front and back. It also tapers across the span.

Made a rough design with fillets milled in. It's a .swk file, and includes all the different parts, labelled as well as I can as tired as I am.

View attachment test.zip

bandman444 said:

Theoretically doesn't a finer sand leave more surface area? Why do we choose to use course paper anyway.

Is it just for the mechanical bite?

Click to expand...

Coarse sandpaper is going to make deeper tracks in the material, but isn't necessarily going to get rid of the oxide layer any faster. Considering the bonding surface, sanding away the oxide with finer paper, then a few quick passes with coarse, to give the epoxy a bit more area to grab onto, might not be a bad idea.

I need to buy a metal polishing kit for these fins. I sanded it with 500grit and it feels extremely smooth, but doesn't look nice.

Maybe some jewelers rouge (sp?) and the polishing attachment on my dremel is all I need.

Click to expand...

500 is too coarse for polishing. If you want to polish it the aluminum, then you need to use rouge -- red rouge will give you the shiniest final result.

If you go the Dremel route, be careful -- if your Dremel grabs and the mandrel hits the fin, you've got a problem. I have a nosecone plug that demonstrates that quite nicely.

Do a quick Google search and you'll find lots of info about polishing aluminum. A lot of them start with fairly coarse sandpaper, which I think you can skip -- you've already got a pretty darned good surface to start from.

After you polish them, you're probably going to want to apply a wax coat, or something similar, to keep them from oxidizing again.

-Kevin

bandman444 said:

Would anyone be interested in a video on me putting on a entire fin?

Start to finish?

Click to expand...

I would love to see that !!


Paul T

Ok here's the video.

I am clearly never going to have a talk show.

[YOUTUBE]GAxbIO-CHNE[/YOUTUBE]

Bryce ,

I think that was a great tutorial you`ve done ,very good information and many things explained , a fine job !!

Thankyou very much for taking the time and sharing with me/us !

Cheers

Paul T

sodmeister said:

Bryce ,

I think that was a great tutorial you`ve done ,very good information and many things explained , a fine job !!

Thankyou very much for taking the time and sharing with me/us !

Cheers

Paul T

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You are welcome. Glad you learned something.

Well sustainer is basically done.


All three fins are on.

I gave myself a very psychological test. I stood on it.

It held! Phew.

I love Blue Tube, but I hate cutting it. I tried out a new process.

I don't have a chop saw, or any other motorized saw.

I had a piece of 3" tubing that I had cut lengthwise for another project the I put next to the line I drew where I wanted to cut it. I then used a small bow (?) saw to cut all the way around. I'm sure it's nothing special, but I really liked the way it turned out, so I thought I would share.













I epoxied on a Aeropack 54mm retainer onto the motor mount with JB Weld after insuring it would fit in the design.



Than I epoxied in the motor mount assembly. This turned out to be a little trickier than I had thought.

Because the aft centering is 3" inside it is hard to get epoxy down in there with less than .5 in a 3"-54mm area.

I tried to think of a solution to get the epoxy down onto the ring without getting it one the Aeropack retainer or worst (as I can't wipe it off easily) the aluminum tube conduits.

I don't have any syringes, so that's out.

I thought that I could use a straw to draw it into the straw then stuck the straw in and release it in the spots I wanted.

I couldn't get that to work well.

So my final resort was to put the epoxy in a cup and pour it around the tube. So I did that, very slow and carefully. Hey? It worked!

Progress progress progress.

If you coat the retainer in grease then no epoxy will ever stick to it again until you extremely thoroughly dissolve it off.

On my newest HP scratch build ,I`m using 6" diam. BlueTube ,and just for fun ,instead of using power tools ,and trust me ,I gots tools baby.....I used a Zona Saw with the fine blade and used it for all my cuts ,even the 4 x 18" long fin slots and 4 x forward fin slots ,not to mention the 20+ or so other tube cuts needed for the project.

The Zona Saw (hobby hand saw) works very well and little effort is needed to cut the tubing.

Take care

Paul T

CarVac said:

If you coat the retainer in grease then no epoxy will ever stick to it again until you extremely thoroughly dissolve it off.

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*facepalm* duh. Oh well. I wrapped tape around it the first time on the booster but blanked completely on the sustainer. Personally I'm not a fan of grease anywhere. Just is a hazard in my opinion and I hate it on my hands.

That's true. If you use Aeropack, grease might make it fall off in flight unlike the finer threaded HAMRs and threaded Slimlines.

So I have gotten more work done on the sustainer of the rocket.


Mainly in the finishing department. I have sanded the fillets smooth and made the transitions between the fins and body tube very clean.

Pictures of all the sides.

I also replaced the nosecone from the plastic LOC cone to the FWFG Wildman Von Karman nosecone. It is quite a bit heavier but that will be a good thing for stability and it gives me room to mount my tracking gear. Plus I think it looks better.

I am playing with the idea of a black rocket with reflective decals and a deep blue nosecone with a polished aluminum tip. The black and deep blue I think will make the Aluminum fins and nose tip pop!

Thanks for looking.

















































Thanks for looking.

I forgot to mention that I am planning on flying the sustainer only on Jan 12th at ROC on a AT J135 or CTI J140 sims to around 10-11k. Should be fun!

I spent $5 at the local hardware store and bought an ultra fine sandpaper set and metal polishing kit. 500, 600,1000,1200grit. Sanded all the fins to a uniform 1200grit finish left them silky smooth. But not mirror like. (The goal of course)
The polishing kit was just a cloth wheel and white and red rougue. The white is supposed to be for aluminum. I am very happy with the finish. Not quite a mirror, but extremely reflective. I may try some other things but am not disappointed with finish that is there.

Tell me what you think.

bandman444 said:

View attachment 108443

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Most amazing fin I've ever seen

bandman444 said:

View attachment 108443

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:eyepop: :drool:

So I put down primer today. Beautiful weather this morning.

I set everything out to dry outside.

I came down for lunch and it was raining. Ruh Roh.

Nothing harmed everything looks good.

Ok, so here is a pretty accurate file of the plans for this rocket.

View attachment 4inch to 3inch two stage test.rkt

I am itching to get a coat of gloss black on her tomorrow morning. (Technically this morning)

I'm not sure if the texture will show up for you guys, but here is a screen shot.



I gotta email Mark to cut me some decals.