The City Slicker: was The Space Cowboy rides again

I decided to take a stab at cutting some Space Cowboy fins on my CNC mill. I contacted Jim Hendricksen and asked for his permission and any information he could give me. Jim didn't just give me permission, he has been really helpful with the background and the problems they ran into before.

They aren't perfect, but I think they came out pretty well for a first try.







Can I get a Yee Haw? :horse:

WOW! I'm building a 54mm md right now and these would be sweet to have. What are you looking at for pricing?

impressive! got to get a sine plate so i could try. Well done

Very nice.

So, are the fins wavy? Can't tell if they are or just milling marks.

cavecentral said:

So, are the fins wavy? Can't tell if they are or just milling marks.

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They just look like milling marks but I could be wrong.

The fins taper from .125" to .036" over 2.625". The passes are .050" wide so each step is around .0008". They feel smooth front to back. Top to bottom you can feel the steps a little. It's nothing that a mill file or some 400 grit couldn't take care of. The edges need to be filed to a sharp edge too, but it only took me a couple minutes to clean this one up.

cavecentral said:

So, are the fins wavy? Can't tell if they are or just milling marks.

Click to expand...

The fins look pretty good. Do they feel stiff? Are you thinking of possibly selling sets? Sign me up.

Yippie Ki Yay, rocket maker! Those look sweet!

Yee Haw!!

nice

Thanks. Yes, they are stiffer than I thought they would be. Yes, I will be selling them soon. I'll probably only be able to a couple sets a week so I'm trying to decide how to price them. It takes over an hour to machine each fin.

4kids49 said:

The fins look pretty good. Do they feel stiff? Are you thinking of possibly selling sets? Sign me up.

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ChrisAttebery said:

Thanks. Yes, they are stiffer than I thought they would be. Yes, I will be selling them soon. I'll probably only be able to a couple sets a week so I'm trying to decide how to price them. It takes over an hour to machine each fin.

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That's great news. I was about to attach fins for my minimum diameter build. I will wait. Is it too early to take a number? lol. Keep us posted.

I've been out of town for a few days so here's an update. I sent Jim H a set of fins on Monday. He should have received them today. I want to hear his opinion on them before I put them up for sale.

Today I stopped by the tool shop to get some new end mills. I cut four fins using different feed rates trying to reduce the machine time. So far they have ranged from 30 to 60 minutes. So far 45 minutes has been the best time with a decent finish. The 30 minute fins looked great on the first side, but the material lifted while it was cutting the second side so I think that's a little too aggressive. I have a couple ideas on how to prevent it, but I'm also down to my last piece of G10. I'm going to try one more thing tomorrow, then I will decide how fast I can consistently cut them. I'm also going to order a stack of G10 tonight.

I think for the first few sets I'll probably just post them on eBay and let you guys decide what they are worth. Once demand falls off I'll set a price and post them on my web store. Sound fair?

Nice work there can't wait to see them in person.

YEE-HAW

I've started a thread in the Vendor's section. Let's keep the commercial chat there. I'll reserve this thread for my build later this spring.

https://www.rocketryforum.com/showthread.php?123262-APE-Space-Cowboy-fin-sets

I haven't made too much progress on this rocket since I started the thread, but I ordered a 36" section of thin wall tubing and an injection molded nose cone from Wildman. They are shipping today.

Unlike the original Space Cowboy I'm using a single break. There's 8" available for the recovery system. I'm planning to deploy a streamer at apogee and use a cable cutter for the main. The booster is long enough to accommodate a CTI 6XL case (L935 or L265).

Here's my initial paint scheme. Nothing fancy. Black Rock tends to be pretty harsh on paint.

Reviving this thread from the dead...

I sanded the booster with 220 grit and then wiped it down with denatured alcohol. Then I epoxied the first fin into place with Rocketpoxy.

I epoxied the last fin in place this morning before work. I'm impressed with how stiff they are now. I'll start fillets tonight.

This will be the highest performing rocket I've built by a factor of three ( my previous altitude record was ~8500). I've been thinking that I'd like something more to show for it than a beeped out number or a Google Earth trace, so I think I'm going to design a mount for my Mobius camera to fit into the altimeter bay. The Mobius is known to interfere with GPS signals, so I'll have to incorporate shielding into the design.

I cleaned the lens on my iPhone this morning. Let's see if this is a little better than the last one.

I made some progress on my altimeter/camera bay this morning. It will add 3" and a couple ounces to the length of the rocket

I got two fillets done today. I'm using about 1g of Rocketpoxy per inch of fillet.

I finished up the fillets yesterday. They look pretty good but there were a couple voids at the ends. I was putting fillets on my Saab so I used the excess epoxy to do a little body work. As it stands the booster weighs 14oz.

I ordered another nose cone, coupler and a short section of body tube from Wildman on Wednesday for my electronics bay. Hopefully they will be here by the middle of the week.

I've been busy making parts for everyone else, so today I did something for myself. I cut the tray for the altimeter bay. A de-cased Mobius ActionCam main board will be mounted on the bottom. A Telemetrum will be mounted on the top. The batteries will be mounted on the back side of their respective electronics. The Mobius camera will be mounted facing the bottom of the board and a Missile Works screw switch will be mounted on the top. There's a support for the antenna at the tip of the tray. I'll glue a 1/8" plastic antenna tube into the support.

I need to order some #0 screws to mount the camera board. I'll have to wait a few weeks until I can buy the Telemetrum.

I made some more progress on the NC altimeter bay over the last couple days. I'm trying to shed as much weight as possible on this build so I'm machining a custom bulkhead. This bulkhead weighs .8oz so far.

Looking good!

I drilled and tapped the bulkhead. Then I drilled and countersunk the holes in the altimeter bay shoulder.

I decided to add a backup altimeter to this project. It's going to be flying ~3x higher and ~1.5x faster than anything I've flown before. I also read somewhere that TRA recommends redundant electronics if you're flying an L or larger motor. I was able to stack a Missile Works RRC2+ on the opposite side of the tray from the Mobius ActionCam board. I also machined a switch mount out of delrin to hold two Missile Works screw switches. The switches are 120 degrees away from the camera so they will be in line with the fins and won't be blocked by the launch tower rails. An Altus Metrum Telemetrum will be mounted above these two. I needed to keep the space behind it clear so that it's GPS antenna won't be blocked. I also finished mounting the Mobius camera's logic board. I think this is rev 4 of the tray now. :blush:

Now I hate all of my altimeter sleds

:y:

That is a gorgeous piece of engineering.